Introduction to concrete polymer materials

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CONCRETE-POLYMERMATERIALS

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DEPARTMENTOF TRANSFORATIONFederal Highway Administration

Offices ofResearch and DevelopmentFHWA-RD-75-507

NOTICE

This document is disseminated under the sponsorship of theDepartment of Transportation in the interest of informationexchange. The United States Government assumes no liabilityfor its contents or use thereof.

The contents of this report reflect the views of the contractingorganization which is responsible for the facts and the accuracyof the data presented herein. The contents do not necessarilyreflect the official views or policy of the Department ofTransportation. This report does not constitute a standard,specification, or regulation.

The United States Government does not endorse products ormanufacturers. Trade or manufacturers' names appear hereinonly because they are considered essential to the object ofthis document.

TECHNICAL REPORT STANDARD TITLE PAGE

5°

12. Sponsoring Agency Name and Addres c

Office of DevelopmentU. S. Department of Transportation

^.Federal Highway Administration,Washington, D.C. 20590

1. Report No.

FHWA-RD-75-507

,

1. Government Accession No.

4. Titleond Subtitle

Introduction to Concrete Polymer Materials,

7. Author(s)

L. E. Kukacka, A. Auskern, P. Colombo

J. Fontana, and M. Steinberg

,8. Performing Organization Report No.

BNL 195 259. Performing Organization Name and Address

Brookhaven National LaboratoryAssociated Universities, Inc.

Upton, New York 11973

3. Recipient's Catalog No.

5. Report Date

April 19756. Performing Organization Code

10. Work Unit No.

11. Contract or Gront No.

DOT-2-1-092613. Type of Report and Period Covered

Course Text

14. Sponsoring Agency Code

15. Supplementary Notes

FHWA Contract Manager: John P. Hall in

16. Abstract

The purpose of this text is to provide highway personnel with a workingknowledge of concrete polymer development and application. Basic informationnecessary to begin experimental application of these materials is presented.

The text presents discussions on the following: (1) a review of concrete-polymermaterials development, (2) knowledge of polymer chemistry as applied to concrete-polymer materials, (3) knowledge of the technology required to produce concrete-polymer materials, (4) a description of the fundamental characteristics andproperties of the composites, and (5) an in-depth study of the applications ofconcrete-polymer materials.

17. Key Words

applications, bridge decks, concretedurability, impregnation, monomer, polymerpolymer-concrete, polymer- impregnatedconcrete

18. Distribution Statement

No restrictions. This document is

available to the public through the

National Technical Information Service,SpringfieJd, Virginia 22151

19. Security Classif. (of this report)

Unclassified

20. Security Classif. (of this page)

Unclassified

21. No. of Pages

156

22. Price

Form DOT F 1700.7 (e-69)

PREFACE

At the request of the Implementation Division of the FederalHighway Administration, an introductory course on Concrete-PolymerMaterials was given by the staff of Brookhaven National Laboratory.The purpose of the course was to provide representatives of StateHighway Departments with a working knowledge of concrete -polymermaterials development and applications.

The course, which was presented in a one -week series of lec-tures and laboratory demonstrations, was designed to provide thefollowing information: (1) a review of concrete -polymer materialsdevelopment, (2) knowledge of polymer chemistry as applied toconcrete-polymer materials, (3) knowledge of the technology re-quired to produce concrete-polymer materials, (4) a descriptionof the fundamental characteristics and properties of the com-posites, and (5) an in-depth study of the applications ofconcrete -polymer materials.

It is hoped that this course and the following text willenable other workers to commence studies that could lead tothe use of concrete-polymer materials in solving some of theimmense problems confronting the highway industry today

.

CONTENTS

Page

Preface iii

Classification and Terminology v

Chapter I Historical Review of Concrete-Polymer Materials Development. 1

Chapter II Review of Concrete-Polymer Materials;Their Preparation, Properties, and 3

Application

Chapter III Introduction to Polymer Science 19

Chapter IV Methods of Producing Polymer- 50Impregnated Concrete

Chapter V Techniques for the Preparationof Polymer-Concrete 67

Chapter VI The Role of Polymer in Polymer

-

Impregnated Concrete 89

Chapter VII Quality Control and NondestructiveTesting of Polymer-ImpregnatedConcrete 111

Chapter VIII FHWA Programs on Polymer-ImpregnatedConcrete 127

Chapter IX Field Evaluation of Polymer-Concrete 138

References 143

Appendix A 148Appendix B . 149

CONCRETE-POLYMER MATERIALS

Classification and Terminology

Three general types of concrete material to which polymeris added to form composite materials are classified as concrete-polymer materials.

1. Polymer-impregnated concrete (PIC) is a precast portlandcement concrete impregnated with a monomer, which is subsequently

polymerized iri situ .

2. Polymer concrete (PC) is a composite material formed by

polymerizing a monomer and aggregate mixture. The polymerizedmonomer acts as the binder for the aggregate

.

3. Polymer cement concrete (PCC) or polymer portland cementconcrete (PPCC) is a premixed material: a monomer or polymer in

the form of a latex is added to a fresh concrete mix and sub-sequently cured and polymerized in place.

Monomers and polymers are incorporated in these materialsfor the purpose of substantially altering some property of thefinal hardened concrete material. Small quantities of polymerare sometimes added to modify the properties of fresh concrete;such materials are more appropriately considered to be admixturesand are not considered in this text.

It- is recognized in the above classification that thegeneral definition of a concrete is an aggregate bound with a

binder. In ordinary concrete, portland cement usually acts as

a binder. In PIC the polymer acts together with the cement binder,and in PC the polymer alone acts as the binder.

The definition of a monomer is an organic molecular speciesthat is capable of combining chemically with molecules of thesame species or with other species to form a polymeric materialof higher molecular weight.

A polymer is defined as an organic material composed of a

series of repeating chemical units (the unit being defined asa monomer) that are linked together chemically.

CHAPTER I

HISTORICAL REVIEW OF CONCRETE-POLYMER MATERIALS DEVELOPMENTM. Steinberg-

After seven years of research and development work, concrete-polymer materials are beginning to emerge from the laboratory intothe field as a material of construction with worldwide potential.

The first sample of polymer -impregnated concrete (PIC) wasproduced at Brookhaven National Laboratory (BNL) in the fall of

1965. Since 1967, under the auspices and with the support ofthe U.S. Atomic Energy Commission's Division of Isotopes De-

velopment (later absorbed into the Division of Applied Technology)

,

and in cooperation with the Bureau of Reclamation (USBR) , BNLhas developed the monomer -material formulations and the methods

of impregnation, measured the structural and durability pro-perties, and initiated development of practical applications.The basic patent on polymer -impregnated concrete (PIC) wasobtained by BNL and is assigned to the U.S. Atomic EnergyCommission (U.S. Patent 3,567,496, March 2, 1971). Initiallythe material was produced by radiation polymerization. However,the thermal-chemical means of initiation is more economical andreadily applied, and the patent covers the thermal-chemical process

The results of this work are summarized in a number ofpublications, notably, five topical reports (1""5) that reviewin detail the information gained and progress made in this work.Lectures and papers on concrete-polymers have been presented atlocal and national scientific, engineering, and trade societies,including the American Concrete Institute, the American ChemicalSociety, the American Ceramic Society, the American NuclearSociety, and the Transportation Research Board of the NationalAcademy of Sciences.

PIC, basically a concrete material, is of interest becauseof its greatly improved structural and durability propertiescompared with those of ordinary concrete. PIC has attractedthe attention of concrete workers and companies around the world,and much development for applications has been initiated bothnationally and internationally.

In the U.S., the Federal Highway Administration (FHWA) hasinstituted programs at BNL' and the USBR on construction of newprecast bridge decks for highway applications. The FHWA and theTransportation Research Board (TRB) have instituted programsin universities and at the USBR and BNL on impregnation of cast-in-place new and - old concrete for the purpose of, first, preventingdeterioration of recently placed concrete, and second, repairingconcrete that has already deteriorated on older bridge decks.The Office of Saline Water (OSW) has supported work at BNL andUSBR to develop chemically resistant PIC for operation at elevated

temperatures in multistage distillation vessels in large sea-water desalting plants. The Bureau of Mines has supported workat BNL on improving the structural stability °f roof and wallstructures in mines . The American Concrete Pipe Associationhas initiated work on PIC pipe for the purpose of producinga stronger and more durable pipe and thus eliminating the needfor costly steel reinforcing. The Department of the Interiorhas supported work at the USBR on producing and testing PIC fortunnel linings for water carriers. The interest in other itemssuch as building block, railroad ties, beams, and ferrocementboats continues unabated .

In foreign countries, interest has been high and applica-tions have been numerous. The Japanese have built a pilot plantand have produced and used PIC for furniture, base plates forpumps in corrosive chemical plants, electric cable covers, heatedroad panels, and underwater structures. The Norwegians have in-stalled PIC curbing on streets in. Oslo. The South Africans havemade PIC mirror concrete for bathroom and kitchen basins, tile,and PIC pipe. The Soviet Union is developing a number of differentforms of polymer-concrete and is beginning to use PIC decorativepanels for building facades in Moscow. An Italian cement companynear Rome has instituted an extensive concrete-polymer programand is using the material in a structural decorative panel for a

high-rise building. England, France, Spain, and Israel also haveindependent programs on concrete-polymers. The American ConcreteInstitute (ACI) has established a committee (ACI-548, Polymersin Concrete) and two symposia have already been held. A state-of-the-art report on concrete-polymer will be issued shortly.Considering that concrete is one of the oldest materials ofconstruction, known for thousands of years, the interest in thedevelopment of PIC and its growth is truly remarkable.

Research on concrete-polymer materials has been expanded toinclude lightweight aggregate PIC, the development of polymerconcrete, and the incorporation of urban solid waste in PICand PC. Glass-polymer composite (GPC) materials are an exampleof the latter; nonreturnable glass bottles or glass-containingincinerator ash is used as an aggregate and is mixed with monomerto produce a strong, corrosion-resistant sewer pipe.

A paper polymer composite (PPC) containing wastepaper ornewsprint has also been developed. This strong, durable, boardlikematerial is suitable for wall board, pallets, and traffic signs.These recycled solid waste materials are of great interest toenvironmental groups and governmental agencies as a potentialmeans of solving part of the country's solid waste disposalproblem.

Stone has also been impregnated with polymer. This materialhas been shown to be of value in mine roof support systems andin the preservation of modern and ancient art work and monuments.

CHAPTER II

REVIEW OF CONCRETE-POLYMER MATERIALS:THEIR PREPARATION, PROPERTIES AND APPLICATION

M. Steinberg

Introduction

The concrete -polymer composite materials development programis directed toward developing both improved and new concretematerials by combining the ancient technology of hydrauliccement concrete formation with the more modern technology ofpolymer chemistry. A wide range of concrete-polymer compositeshave been investigated

.

Polymer-Impregnated Concrete Materials Development

Polymer-impregnated concrete (PIC) is a precast and curedhydrated cement concrete that has been impregnated with a lowviscosity monomer and polymerized iri situ . This material is

the most developed of the composites. The greatest improvementsin structural and durability properties have been obtained withPIC. With normal-weight concrete, compressive strengths can beincreased from 5000 to 20,000 psi. Water absorption is reducedby 99%, and the freeze-thaw resistance is enormously improved.With high-silica cement, strong basaltic aggregate, and high-temperature steam curing, strength increases from 12,000 toover 38,000 psi can be obtained. The tensile strength of PICis about ten times less than the compressive strength, as inconventional concrete. A maximum tensile strength of 3500 psihas been obtained with the steam-cured concrete. With fog-cured concrete, polymer loadings (e.g.) polymethyl methacry late,

(PMMA) , of about 6% by weight (wt polymer/wt of dried concrete)are obtained. A freeze-thaw test specimen of PIC is shown inFigure 2-1, and a sample exposed to chemical attack by acidsis shown in Figure 2-2

.

After impregnation, conventional concrete is transformedfrom a plastic material to an essentially elastic material,as indicated by the linearity of the stress-strain plot for PICin Figure 2-3. The modulus of elasticity is increased by atleast a factor of 2. The ability to vary the shape of thestress-strain curve presents some interesing possibilties fortailoring desired properties of concrete to particular structuralapplications. This may be achieved by adding plasticizers tothe monomer systems or varying the type and shape of aggregate,e.g., steel fiber aggregate.

In contrast to conventional concrete, PIC exhibits essen-tially zero creep properties, as shown graphically in Figure 2-4.

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Figure 2-1. Freeze-thaw test on polymer-impregnated concrete. PIC

contains 6 wt. % PMMA and lost 0.5% weight. Control lost 26.5%.

Figure 2-2. Resistance to Chemical attack (15% HCL). PIC lost 7%weight after 497 days. Control lost 25% in 105 days.

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Figure 2-3. Compressive stress-strain curve for PMMA-impregnated concreteImpregnated concrete shows elastic behavior; unimpregnated concrete showsplastic behavior.

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PIC is produced by drying cured conventional concrete bythe most convenient and economical processing technique (hot

air, oven, steam, dielectric heating, etc.), displacing theair from the open cell void volume (vacuum or monomer displace-ment and pressure), diffusing a low viscosity monomer (<10 cP)through the open cell structure, saturating the concrete withthe monomer and polymerizing the monomer jln situ to a polymerby the most convenient and economical means (radiation, heat,or chemical initiation. Figure 2-5 is a schematic flow sheetof a process utilizing thermal-catalytic polymerization. Free-radical vinyl-type monomers, i.e., methyl methacrylate (MMA)

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styrene, acrylonitrile, tert-butvl styrene., and other thermo-plastic monomers, are generally used in the production or PIC.For increased thermal stability, cross-linking agents and thermo-setting monomers such as styrene-trimethylolpropane trimeth-acrylate (TMPTMA) and polyester-styrene are used. The moreimportant process criteria are that the monomer should be ofrelatively low cost, readily available, and of relatively lowviscosity. Much information on the formation and propertiesof PIC has been accumulated over the past five years in theU. S. Table 2-1 gives a brief summary and classificationof PIC materials and their properties. A U. S. patent hasalso been issued on the method of producting PIC.^ 6 '

Polymer -Cement Concrete Materials Development

Polymer-cement concrete (PCC) is a premixture of hydratedcement paste and aggregate to which a monomer is added prior tosetting and curing. The introduction of various organic materialsto a concrete mix has been extensively investigated elsewhere '7)

as well as at BNL . The improvements obtained in strength anddurability are either disappointing or relatively modest. Inmany cases the resultant materials are inferior to concrete.Under the best conditions compressive strength improvementsover conventional concrete of ~50% are obtained if relativelyhigh polymer concentrations, of the order of ~30%, are used

.

Polyester-styrene, epoxy-styrene, furans, and vinylidene chloride

have been used in PCC with limited success because most organicmaterials are incompatible with aqueous systems and in manycases polymerization either is inhibited by the alkalinity ofthe cement phase or interferes with the cement hydration process.In addition, porosity develops as a result of shrinkage duringthe curing process and many pores remain unfilled. With PIC,the polymer fills the voids and the strength, which is a functionof the filled pore fraction, is therefore increased to a highdegree

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The incentive to attain an improved premix concrete materialis that it can be cast in place for field applications, whereasPIC requires a precast structure.

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A variation of PCC is the addition of a modest amount ofpolymer latex such as styrene-butadiene or polyvinylidene chlorideemulsion to the fresh concrete mix. The amount of polymer addedto the mix is less than 4% by weight of the total mix. Polymeriza-tion is not part of this process. The polymer particles coalesceduring the concrete curing process and coat the pore structure ofthe concrete. The strength is improved by only a factor of 2,

but durability is significantly increased.^ 8 '

Polymer Concrete Materials Development

Polymer -concrete (PC) is an aggregate bound with a polymerbinder. This material can be mixed and cast in the field. Itis called a concrete because, by the general definition, concreteconsists of any aggregate bound with a binder. The cheapestbinder is portland cement, which costs about 1.25<:/lb in theU. S. Polymer can also be a binder; however, it is more costlythan hydrated cement; price's vary from 10£/lb to 40C/lb for themajority of commercial polymers. Because of the energy crisis,petrochemicals as well as cement have rapidly increased in costduring the past year.

Polymer filled with aggregate, for example, plastic contain-ing powdered walnut shells, has long been used in table tops andfurniture products. PC is an aggregate filled with a polymer.The main technique in producing PC is to reduce the void volumein the aggregate mass to minimize the quantity of the relativelyexpensive polymer needed for binding the aggregate. This is

accomplished mainly by grading and mixing the aggregates . Forexample, to obtain a void volume <20%, an aggregate mix con-sisting of 3/8 - 1/2-in. stone (60.7 wt %) , 20-30 mesh sand(23.0%), 40-60 mesh sand (10.2%), and 170-270 mesh sand (6.1%)is required. Conventional concrete mixing equipment can be usedto prepare the mix. Safety precautions must be strictly observedwhen handling the flammable monomers.

There is another reason for furthering the development ofPC materials. In conventional concrete, the alkaline portlandhydraulic cement forms voids and cracks during hydration. Watercan intrude and crack the concrete, and the alkaline cement isattacked by acidic media. With polymer as a binder, most ofthese difficulties are overcome. The polymer can be made compactwith a minimum of open voids, and most polymers are hydrophobicand resist chemical attack. As shown in Table 2-1, the compressivestrengths of PC can be as high as that of PIC (~20, 000 psi) .

The monomer loadings are also comparable (6%)

.

A silane coupling agent can be added to the monomer to

11

improve the bond strength between the polymer and the aggregate

.

The main problems arise from the viscoelastic properties of thepolymer . Polymers usually have a low modulus of elasticity,which means that they are flexible and exhibit creep. This isthe primary reason why plastics are not used alone in structuralmembers. By using polymer as a binder for aggregate, some ofthese difficulties are overcome and there is a good possibilityof developing an important new class of materials with highbenefit-to-cost ratios. It is known from the open literaturethat in the USSR^ the development of PC is more advanced thanin the U. S. Before PC is accepted as a reliable material ofconstruction, much more investigation and experience will berequired

.

Aggregate Compositions

Consideration is now given to the aggregate in the binder-aggregate concretes or composites. The cheapest and most abun-dantly available aggregates are natural stone and sand, whichare widely used throughout the world. There are a number oftypes and grades of stone aggregates which basically relate toigneous (granite), metamorphic (slate), and sedimentary (sand-stone) stone . Aggregates are also classified as standard weight,structural lightweight, and insulating lightweight. Among thevarious lightweight polymer-impregnated concrete materials,perlite has been used to produce a material that is lighter thanwood and compressively as strong as concrete. This opens uppossibilities for producing lightweight, structurally strongmortars and concretes that are buoyant and have a high strength-to-weight ratio.

The properties of the various concrete-polymer materialsproduced to date are summarized in Table 2-1. The data includesurface-coated (SC) and partially penetrated PIC (referred to ascoated in-depth concrete, CID) . The results of an attempt to

combine the strength, durability, and manufacturing cost intoa benefit/cost ratio for each of the materials are given inTable 2-1.

Urban Waste Utilization

Urban solid waste, such as garbage, refuse, sewage,paper, glass, and metal, can be used as aggregates. Sewageand solid-waste refuse polymer-impregnated concrete has beenproduced, with garbage used as the aggregate and sewage asthe hydrating media for the cement. After curing, theconcrete was dried, impregnated, and polymerized in. situ withuse of radiation. Compressive strengths as high as thatof conventional concrete can be obtained (see Table 2-2)

.

12

Newsprint has been soaked in monomer and polymerized in situunder pressure to produce a material called paper polymer composite(PPC), or paper plywood. This composite has very good tensilestrength along the plane of the paper (7500 psi) .

Nonreturnable glass bottles have been crushed and graded and

the mixed particulate glass filled with monomer in a mannersimilar to that used for PC. The polymer-bound broken glass isalmost as strong as PIC and highly resistant to attack bycorrosive media. The variously sized glass particles and a

sample of the composite material are shown in Figure 2-6. Anapplication of this material is for sewer pipe (Figure 2-7),

especially when acid wastes are handled or when the hydrogensulfide gas coming from sewage is oxidized under aerobicconditions to sulfuric acid. This material is called glasspolymer composite (GPC) . Conventional concrete is unsuitablefor this environment; therefore asbestos cement and vitreousclay or cast iron pipe are usually specified.

Decorative bricks and facings for buildings can also bemade from GPC. Incinerator ash has also been used as aggregateto produce a structurally sound material. Table 2-2 summarizessone of the properties of solid-waste-refuse polymer-concretematerial. It is hoped that this materials development work willresult in converting a negative ecological value into a positiveasset in the form of valuable construction materials.

Applications Development

A number of applications for concrete polymer materials arebeing investigated. The Federal Highway Administration (FHWA)

is sponsoring research to determine the feasibility of usingprestressed PIC panels for bridge decking .

^

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of Saline Water (OSW) has been investigating the use of PICfor the construction of economical and durable distillationvessels for use in desalting plants. The Bureau of Mines (USBM)is investigating the chemical stabilization of coal mine roofsby impregnation of the stone (H) with monomers followed byin situ polymerization. The USBM is also developing a pumpableroof bolt.' 1

' PIC tunnel linings are another application ofinterest to the Bureau of Reclamation (USBR) . The U. S. Navyhas been interested in the use of PIC for underwater habitatsand piling. PIC is also being considered for beams and buildingblocks for durable housing. The American Concrete Pipe Association(ACPA) , in cooperation with the U. S. Atomic Energy Commission(US AEC) and the USBR, has investigated the use of PIC forsewer and pressure pipe. There is also interest in PIC railroadcrossties . A number of industrial associations in the U. S.

are investigating concrete-polymer materials for their ownparticular applications.

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In Japan, a construction company in conjunction with a

chemical company is reported to have constructed a 15 ton/daypilot plant for experimental production of PIC with use ofthermal-catalytic initiation. The material has been namedPowercrete, and beams, panels, and pipe have been produced.

A firm in the Union of South Africa is reported to haveconstructed a pilot plant for the thermal-catalytic productionof PIC with use of a special type of concrete with smooth surfacescalled mirror concrete. In addition to pipe and building concrete,a market for domestic sanitary ware such as wash basins, bathtubs,and sinks is being explored.

A cement association in Italy and the University of Rome arecollaborating in developing PIC. They are using a high-strengthconcrete containing silica cement, high-pressure steam curedand polymerized under water. Possibilities exist for con-struction of ship plate and sewer pipe and for producing nutsand bolts and such items as screw-ended concrete sewer pipe.

Investigators in Norway, Denmark, Belgium, France, Spain,England, and Israel are exploring PIC applications, includingheated road panels, curbing, base plates for pumps, and windowsills

.

Extensive work has been conducted in the USSR on developingand applying PC. The Russian literature

(

9) indicates significant

advances in a number of applications, including tunnel supports.A number of universities around the world have initiated

studies on concrete-polymer materials.Preliminary cost estimates indicate that PIC materials

could be competitive with other conventional materials ofconstruction. The feeling is that the field of concrete-polymer materials, in which an ancient materials technology(concrete) is combined with a new materials technology (polymer)

,

is a growing and exciting one. Given the opportunity of additionalinvestigation, demonstration, and experience, it is believedthat concrete-polymer materials can become an important class ofconstruction materials.

Storage of Nuclear Waste Materials

Another potentially important application for hydrauliccement concrete, in combination with the polymers in PIC andPC, is the storage of long-lived radioactive waste from thenuclear power industry. A major unsolved problem facing theexponentially growing industry is the safe disposal of fissionproduct wastes . A technically and economically reasonableapproach taken by the AEC is to immobilize the fission productsin long-term durable materials in an engineered storage system.The material must be stored for 1000 years before it can be

17

considered biologically safe. Since it has been used in someenvironments for much longer periods of time, concrete appearsto be an attractive material for accomplishing this goal.Further, concrete ingredients are low in cost and readilyavailable. Adding the new dimension of PIC and PC can ensureadditional durability and strength factors. The radioactivewaste materials requiring storage are in the form of solublesalts, aqueous solutions (nitrates) , oxides, glasses, andcontaminated process equipment. The US AEC has established a

program at. BNL for investigating conventional concrete, PIC,and PC formulations for this application. The radiation stability,leachability, thermal stability, and structural integrity ofpromising formulations are being studied. Much more will haveto be learned about these materials before it can be confidentlypredicted that they will last a thousand years or more. Todate, mortars and concretes containing formulations of aqueousnitrates with calcium aluminates have been produced. Afterimpregnation with styrene-divinyl benzene, they have shownradiation stability to 10 rads . This is the total integratedradiation dose expected for 1000 years of exposure. Cross-linked polystyrene is especially radiation resistant. Thecompressive strength of these materials is ^13,000 psi.

18

CHAPTER IIIINTRODUCTION TO POLYMER SCIENCE

Peter Colombo

Introduction

This chapter is an introduction to monomers and polymersfor specific application to polymer-impregnated concrete (PIC)

and polymer-concrete (PC) composites. It is intended to givehighway engineers and field personnel a general understandingof the subject. The text is based on known concepts in polymerscience and on the knowledge gained in laboratory and fieldexperiments on concrete-polymer materials. Emphasis on someaspects of the subject reflect the thinking and experience of theauthor in relation to FHWA applications . A more thorough andcomplete treatment of the use of monomers and polymers forPIC and PC composites is provided in the references and inother chapters of the text.

1 . Definitions

A monomer is a molecular species capable of combiningchemically with molecules of the same or other species, to

form a high molecular weight material known as a polymer.A polymer consists of chains of repeating units derived

from the interreaction of monomer units.In general, the monomer is the starting material, and

the polymer is the end product. The chemical process throughwhich the conversion from monomer to polymer takes place is

called polymerization .

When a monomer such as methyl methacrylate is polymerized,the process is called homopolymerization and the homopolymerpolymethyl methacrylate is formed . When more than one chemicalspecies, e.g., a mixture of methyl methacrylate and styrene, ispolymerized, the process is called copolymer ization and a

copolymer is formed

.

Figure 3-1 is a schematic representation of a homopolymer

.

Each small circle in the polymer chain represents a monomermolecule. During the reaction, the monomer molecules chemicallyattach themselves to one' another to form chains that are very]ong and flexible and become entangled during polymerization.The illustration in Figure 3-1 represents a homopolymer, sinceall the molecules that make up the polymer chains are alike.Examples of homopolymers are polystyrene and polymethylmethacrylate. Polymer chains consist of thousands of monomerunits, all chemically tied together. The mechanical and thermalproperties of many polymers are dependent on the length ofthe polymer chains

.

19

Figure 3-1

A schematic representation of a polymer. The spheresrepresent the repeating units of the polymer chains

20

Copolymers can be made in a number of different geometricarrangements, some of which are illustrated in Figure 3-2.

The most common configuration resulting from copolymer izationinvolving two monomer species is a random copolymer . Duringpolymerization, the monomer molecules add along the chain ina random manner, as indicated by the light and dark circles inFigure 3-2. Alternating • copolymers are formed as a result ofa strong tendency for the monomer molecules to alternate duringpolymerization. Block copolymers (Figure 3-2) consist ofalternating sequences of homopolymers chemically bound to formlong polymer chains. Graft polymers are those made by "grafting"chains of one polymer onto a "backbone" of a second polymerby means of chain transfer reactions.

Homopolymers have specific mechanical and chemical properties

By combining homomonomers in the proper proportion, copolymershaving the most desirable properties for a specific applicationcan be formed . More complete information on definitions inpolymer chemistry can be found in Ref s . 13 and 14

.

2 . Polymerization Processes

The processes of polymerization are divided into two groupsknown as addition and condensation polymerizations.

Addition Polymerization

An addition polymerization process is one in which themonomer molecules combine through the formation of free radicals.This process is characteristic of vinyl monomers that containthe grouping -CH=CH- . A typical addition polymerization processinvolving styrene and methyl methacrylate is as follows:

CH2=CH

X-CH2-CH-

X

V VSTYRENE MONOMER REPEATING UNIT

-CH 2-CH-

Xv

POLYSTYRENE

/CH3

CH2=C

C00CH3

METHYL

METHACRYLATE

/CH3

-CHjTC-

COOCH3

REPEATING UNIT

21

/CH 3

-CH -C-

COOCH3Jn

POLYMETHYL

METHACRYLATE

o o O

(a)

(b) xA*^»*»(O

(d)

Figure 3-2

Copolymer arrangements(a) a random copolymer, (b) alternating copolymer,

(c) a block copolymer, (d) a graft copolymer

22

Styrene and methyl methacrylate monomers react through thedouble bond to form long chains of homopolymer having the samerepeating unit. In the above process only polymer is formed.There are no by-products to be eliminated.

Condensation Po lyme r i zat ion

This process involves the reaction between two monomermolecules, which are usually chemically different, to form a

new chemical bond between the two. The molecular formulaof the repeating unit is different from that of the monomer.Two examples of the condensation process are given below.

CI-C-0-R-O-C-CI + HgN-R-Nl^—-C-0-R-0-C-NH2-R-NH- 2HCI (I)

BICHLOROFORMATE DIAMINE . POLYURETHANE BY-PRODUCT(REPEATING UNIT)

<P, *° 'P 'P

H0-C-(CH2)4-C-C-0H + H2N-(CH2)6-NH2-^-NH-(CH2)6-NH-C-(CH2)4-C- HgO (2)

ADIPIC ACID HEXAMETHYLENEDIAME 6-6 NYLON BY-PRODUCT

For applications in polymer-concrete and polymer-impregnatedconcrete, condensation reactions are difficult to perform sinceextremely high temperatures and acid-type catalysts are usuallyrequired to initiate the reaction. In addition, the by-productelimination inherent in most of these reactions is detrimentalto the composite. More detailed descriptions of addition andcondensation polymerization processes are given elsewhere . (15, 16)

Addition-Type Monomers

Under normal conditions of temperature and pressure, monomersare in the form of liquids, solids, or gases. Several addition-type monomers are listed in Table 3-1. The liquid-type monomersin the table are those that have been considered by BNL to bemost suitable for the impregnation of precast concrete and forthe production of polymer concrete composites . (2-4) Solid-type monomers are not used since they can be added to a mixonly as aggregate and therefore do not fill the voids andcapillaries formed during hardening of the concrete. Sincetheir bonding properties with sand or other aggregates are poor,they cannot be used for producing polymer-concrete composites.Gaseous-type monomers have been used for impregnating precastconcrete."' 3

) Although the test results were satisfactory,the techniques and equipment required are impractical, particularlyfor field application.

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3 . Monomer -Polymer Properties

The monomers that have been used for FHWA applicationsand some of their most important physical properties are givenin Table 3-2. Based on the viscosity values shown, all themonomers can be used for polymer -concrete composites. Styreneor methyl methacrylate can be used alone or in combination withtrimethylolpropane trimethacrylate tPMPTMA) . Polyester-styrenecan be used as is, or it can be further diluted with styrenemonomer to decrease viscosity. With the exception of polyester-styrene, which has a high viscosity, the monomers listed in

Table 3-2 can also be used for impregnating precast concrete.The high boiling points and low freezing points of thesemonomers give them great applicability over a wide range oftemperature conditions.

The flash points and explosive limits of the monomersin air are also given in Table 3.-2 . The flash point is

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Mechanical Properties of Polymers

The tensile, compressive, and flexural strengths forpolystyrene, polymethyl methacrylate and polyester-styreneare given in Table 3-3. These properties exhibit wide rangesand depend on many conditions such as impurities, polymeriza-tion temperature, catalyst concentration, and catalyst type.

Chemical Stability of Polymers

Important properties of polymers are resistance toacidity, alkalinity, and solvents. The effects of thesematerials on polystyrene, polymethyl methacrylate, andpolyester-styrene are summarized in Table 3-4. Sunlighttends to oxidize the surface of polystyrene and polyester-styrene, which results in a slight discoloration. Thiseffect is not detrimental to the overall properties of thepolymers. The effect of sunlight on polymer-impregnatedconcrete and polymer-concrete composites containing thesepolymers is negligible, since the amount of polymer on thesurface of the composites is small. As indicated in Table 3-4,all the polymers are resistant to weak acids. Strong acids,particularly the oxidizing types such as nitric and hydrochloricacid attack polystyrene and polymethyl methacrylate. Weakalkalines have no effect on the polymers, but strong alkalines

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such as concentrated sodium hydroxide attack polymethylmethacrylate and polyester-styrene . Organic solventsdissolve polystyrene and polymethyl methacrylate. Thepolyester-styrenes may be attacked causing a small amountof degradation but they do not dissolve since they are cross-linked polymers which are highly resistant to solvents.

Cross-Linking Agents

Homopolymers of styrene and methyl methacrylate consistof tightly packed polymer chains held together by Van der Waalsforces. At high temperature, thermal motion overcomes thephysical bonds (Van der Waals forces) between chains, andthe chains slip past one another. The polymer goes from a

hard glassy material to a rubbery or flowable liquid. Oncooling, the polymers revert to their original form. When anappropriate solvent is added to these polymers, it penetratesthe interface between polymer chains and thus reduces thephysical forces; this allows the chains to slip past one anotherand go into solution. Such polymers are called thermoplastics .

It is also possible to link the polymer chains of thermo-plastics with strong chemical bonds through the use of cross -

linking agents. Cross-linking agents are polyfunctionalcompounds capable of taking part in two separate addition reactionssimultaneously to form a three-dimensional network. The cross-linking agent used at BNL for improving the thermal and solventresistant properties of polystyrene and methyl methacrylate is

t rimethylolpropane trimethacrylate (TMPTMA)

.

Two cross-linking arrangements are shown in Figure 3-3

.

The upper arrangement (Figure3-3a) shows cross-linked polymerchains in which small chain segments consisting of polymer-likemolecules act as cross-links between the main polymer chains.The lower arrangement is one that is produced when a singlemolecule binds the segments of the main polymer chain. Thedegree of cross-linking and the arrangement depend on the natureof the polymer chains and on the type and concentration ofcross-linking agent.

4 . Free-Radical Polymerization

The polymerization of unsaturated monomers such as styrene,methyl methacrylate, and polyester-styrene is typically a chainreaction. Polymerization can be Initiated by the action of a

free radical on a monomer molecule, which may lead to polymerchains consisting of thousands of monomer molecules. Freeradicals can be formed by the decomposition of a relativelyunstable material called an initiator or a catalyst. Figure 3-4

describes the mechanism involved for a free-radical-initiatedaddition polymerization. The initiator molecule, shown inFigure 3-4, is benzoyl peroxide, a commonly used initiator.

—

Figure 3-3

Cross-linking arrangements(a) cross-linked polymer chains in which small chainsegments act as cross-links, (b) cross-linked polymer

chains in which foreign atoms or molecules are the cross-links

30

Addition Polymerization

Free radicals are formed by the decomposition of a relatively un-

stable material called an initiator

OII

c-o

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O

C-O- + CH„=CHXII

2

(free radical) (vinyl monomer)

C-OCH CHX*

(growing polymer chain)

Monomers add successively to the growing chain in a matter of

seconds. Finally two free radicals combine to terminate polymer chain

growth.

C-0-(CH CHX)2 n

> inactive polymer

(growing chain) (polymer)

Figure 3-4

31

When subjected to heat or in the presence of a promoter, themolecule splits at the 0-0 bond to form two free radicals thathave unpaired electrons and are thus very reactive. A formedfree radical attacks a monomer molecule, the double bond is

broken, and a monomer molecule with an unpaired electron isproduced . The new free radical seeks out another monomermolecule, the sequence is repeated, and the result is a growingpolymer chain. The growing chains end when all the monomer isconsumed or when two growing chains meet end to end . Many ofthese reactions take place at the same time. The rate of polymeriza-tion can be controlled by varying the initiator (catalyst)concentration and or the temperature. In general, the lowerthe initiator concentration and temperature, the lower thepolymerization rate.

Promoters can be used instead of temperature for room-temperature curing of some catalyzed monomer systems. Promoters(also called accelerators) are chemical compounds that inducethe decomposition of a peroxide catalyst by breaking the 0-0bond. This reaction can take place over a very wide temperaturerange, depending on the promoter-catalyst system used. Fornormal temperature use, the promoter-catalyst combinationslisted in Table 3-5 yield the best results. These systemsallow a reasonable working time before the mixture sets orbecomes unworkable. The concentration, of promoter and catalystfor a given mix affect the cure time. The effect of concentra-tion on cure time for polymer-concrete composites is discussedin Chapter V and Appendix A. If a temperature cure is preferredto a promoter-catalyst cure, the same catalysts (Table 3-5) canbe used for initiating the polymerization reaction. Thetemperature requirements for thermal-catalytic polymerizationvary with catalyst. This is also discussed in Chapter V.

5 . Plasticizers

Plasticizers can be defined as chemically and thermallystable organic materials used to modify the physical propertiesof polymers. In most applications, plasticizers are used toimpart flexibility, which the polymer in its original statedoes not have

.

As discussed previously, polymers consist of a series oflong, threadlike chains, more or less randomly arranged. Forthe polymer to be flexible and extensible, the polymer chainsmust be free to slide past one another . In an unplasticizedstate, this relative motion of the chains is restricted becauseof the physical or Van der Waals forces between the polymerchains and to mechanical entanglement. The strength of thesebonds determine the rigidity or flexibility of the polymer.When plasticizers are added to the polymer, they act to loosenthe bonds between polymer chains by neutralizing the physical

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forces and thus allow the chain to slide past each other more

easily

.

The polymers used for FHWA applications (Table 3-3), can

be classified as strong and brittle materials. In forming

polymer-impregnated concrete and polymer-concrete composites,

the sand and stone aggregate, and the portland cement concrete

used in the formulations can also be classified as strong and

brittle materials. These composites can fail catastrophically

under certain conditions of stress or impact. If plasticizers

are used to improve the flexibility or resilience, the composite

will be capable of absorbing higher impact loads.

Plasticizers can generally be divided into two types,known as external and internal plasticizers. The externaltype does not enter into a chemical reaction with the polymerand can eventually migrate out of the polymer, depending ontime and on the environmental conditions. When this occurs,the polymer properties approach those of its original state.

Plasticizers of the internal type are more desirable, sincethey become an integral part of the polymer chain throughchemical reaction. These materials are usually monomers whichpolymerize to form very flexible homopolymers . Addition ofthese monomers to a base monomer such as styrene, methylmethacry late, or polyester-styrene prior to polymerizationresults in copolymers with mechanical properties differentfrom those of their respective homopolymers. Figure 3-5 showsthe effect of a plasticizer on the compressive stress-straincharacteristics of a polymer-concrete composite containingmethyl methacrylate . The composite is an elastic materialover the range of stress indicated by the linear portion ofthe curve. The breaking stress, taken where curve a ends,is only a few percent from that of the yield stress (wherethe curve departs from the linear portion of the curve)

.

Addition of 5% butyl aery late had little effect on the stress-strain properties of the composite (curve b) . A significanteffect was noted when 20% butyl aery late was added to thebase monomer . Curve c indicates a more ductile materialhaving a higher impact strength than that of the base monomer.This is indicated by the shape of the stress-strain curve:the break point is well beyond that of the yield point.

The use of plasticizers in polymer-concrete compositescan extend the use of these materials to applications in whichimpact load is an important criterion. Since the binderfor a polymer -concrete material is the pqlymer, the mechanicalproperties of the composite can be varied to reflect thoseof the polymer. The effects of plasticizers are less pro-nounced for polymer-impregnated concrete, where the cementphase is a binder. The polymer loadings (~6 wt %) are toolow to exert any significant change on the plasticity ofthe composite. •

34.

1, , r

(c)

_L i.

2000 4000 6000 8000 10000

STRAIN, ^.in./in.

Figure 3-5 Compressive stress-strain curves for polymer-

concrete. Curve a, MMA; curve b, 95 wt % MMA - 5 wt

% butyl acrylate; curve c, 80 wt % MMA - 20 wt % butyl

acrvlate.

35

6 . Si lane Coupling Agents

Two types of bonding can take place when a monomer is

polymerized in the presence of sand or other silica-containingaggregate. One type involves a chemical bond at the inter-face between the inorganic substrate and the organic polymer

.

The second type is physical bonding, in which the polymer andaggregate are held together by Van der Waals forces.

Most of the stress in a polymer-impregnated concrete orin polymer -concrete is carried by the aggregate or cementphase . The polymer matrix serves to distribute the loadover as wide an area as possible by filling cracks, voids,and other discontinuities that occur during formation ofthe composite. This type of load spreading requires thatthe stress be transferred across the interface betweenaggregate and polymer. Stress can be transferred betweenthe two materials only if they are in intimate molecularcontact. If separation occurs, "even at the molecular level,as a result of shrinkage, temperature, water intrusion, orfor any other cause, the ability to transfer stress is de-creased appreciably. Bond energies resulting from chemicalbonds are ~20 to 150 kcal/mole, an order of magnitude higherthan those of physical bonds. It therefore appears thatchemical bonds are preferred over physical bonds. Tests (5)

have indicated that the type of bonding that normally takesplace between polymer and siliceous materials is a physicalbond .

Chemical bonding can be induced by use of silane couplingagents. These agents consist of molecules having two differenttypes of reactivities. One portion of the molecule is organicand is capable of reacting with a variety of monomers. Theother portion is inorganic and reacts with silica to form a

chemical bond

.

The reactions that take place between silane couplingagents, sand, and polymer are illustrated in Figure 3-6.

Upon exposure to moisture, y-rc^thacryloxypropyl trimethoxysilane(a coupling agent) forms a silanol which reacts rapidly withsilica to form a chemical bond . In the presence of a monomersuch as methyl methacrylate and a chemical initiator, theorganic portion of the molecule reacts by a free-radicalmechanism to form long polymeric chains.

The methods that can be used to apply silane couplingagents to polymer -impregnated concrete and polymer -concretecomposites are given in Table 3-6. The simplest method andthe one currently being used for FHWA applications is that inwhich the silane is mixed with the monomer prior to contactwith sand or precast concrete. However, as indicated by thecompressive strength values given in Table 3-6, this methodis not the most efficient.

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The effectiveness of silane coupling in polymer-concretecomposites is further demonstrated in Figure 3-7. Polymer-concrete specimens prepared with and without a silane couplingagent were subjected to tensile splitting tests. Theupper specimen, prepared without the use of a coupling agent,failed primarily because of the poor bond between the polymerand aggregate. This is indicated in Figure 3-7 by the voidscreated by the dislodgment of the aggregate from its bedding.The lower specimen, prepared with a coupling agent, failed becauseof fracture of the stone aggregate . In this specimen thepolymer-aggregate interface remained essentially intact.

Polymer-concrete specimens prepared with and withouta coupling agent were exposed to boiling benzene for 24 hr

.

Benzene is a strong solvent for the methyl methacrylate usedas the base monomer for these composites. The results ofthis test are shown in Figure 3-8. The polymer in the compositethat did not contain silane completely dissolved away from theaggregate . The polymer in the composite containing silanedid not dissolve, and the specimen retained its originalconfiguration

.

7 . Flammability

All organic materials, including polymers, burn vigorouslyin the presence of oxygen. However, materials can be addedto monomers and polymers to reduce the flammability. Thesematerials mainly contain chlorine, bromine, antimony, andphosphorous. To be effective as flame retardants, largeconcentrations of these materials are generally required

.

This normally has an adverse affect on the mechanicalproperties of the polymer

.

A series of flammability tests was performed to determinethe relative burning rates for polymers, polymer-impregnatedconcrete, and polymer -concrete composites.^) The flame test,designated ASTM-D-635-68, measures the relative burning ratesof self-supporting plastics. The apparatus for this test is

shown in Figure 3-9 . In accordance with the test, a flameis played on one end of the specimen for 30 sec. The flameis then removed and the burning rate is measured. Figure 3-10shows the results of a test in which the material proved tobe self-extinguishing. The results of tests on various compositematerials are given in Table 3-7. With the exception of chloro-styrene, all the homopolymers were rated as flammable by thistest. The chlorine component in the chlorostyrene moleculeconstitutes a "built-in" flame retardant.

The burning characteristics of polymers incorporated intopolymer-impregnated concrete and polymer-concrete composites aredrastically different from those for homopolymers. Under the

39

POLYMER CONCRETE

METHYL METHACRYLATE

METHYL METHACRYLATE + SI LANE

Figure 3-7. Fracture surfaces of PC specimens. Top: specimens pre-

pared without si lane coupling agent, tensile splitting failure occurred

at polymer-aggregate interface. Bottom: specimen prepared using

si lane, failure occurred through aggregate.

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conditions of the test described above, polymer-impregnatedconcrete and polymer-concrete composites are either self-extinguishing or do not burn. The polymer on the surfacesof the composites that had been exposed to a flame wasobserved to burn or to pyrolize and leave a charred residue,which formed a protective blanket for polymer beneath thesurface

.

8 . Storage and Handling of Monomers

Most monomers, including those described in this sectioncontain inhibitors when they are shipped by the manufacturers.Inhibitors are chemical compounds that prevent prematurepolymerization in two ways:

(1) They can react with and deactivate the free radicalin a growing chain.

(2) They can act as an antioxidant and prevent polymeriza-tion by reacting with oxidation products that may be formedin the storage vessel through contamination or through theformation of peroxides from oxygen in the air.

In general, inhibitors serve as free-radical scavengers.The inhibitor level must be maintained above a minimumconcentration, or danger level, at all times. If the concentra-tion is allowed to drop below this danger level, the amountremaining may not be adequate to prevent a premature or runawaypolymerization. The danger level for styrene is <^4 to 5 ppm.Maintaining the inhibitor concentration in the 10 to 50 ppmrange gives adequate control.

The time required for initial inhibitor concentrationsto fall to a dangerous level varies greatly with storage andhandling conditions. Factors affecting the depletion ofinhibitor are heat, water, and air,, with heat the mostimportant. In hot climates (normal temperatures >30 C),the bulk monomer should be cooled.

Drums of monomer should not be permitted to stand in the sunfor more than a short time. As soon as possible after beingreceived, monomer should be placed in a cool, shaded area.In hot weather, drums can be cooled by water spray. It is

also advisable to keep inventories to a minimum during hotweather and use them in the order received so that monomeris not stored any longer than necessary. Table 3-8 lists theinhibtiors used by the manusfactuers of various monomers.Typical inhibitor concentrations for each monomer at time ofshipping are also given. It should be noted that the inhibitorconcentrations that are normally available vary widely. Theconcentrations given in Table 3-8 have been satisfactory forwork at BNL.

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There are various chemical methods for monitoringinhibitor concentration. A fast and simple method developedat BNL is described in Chapters IV and V. Since the inhibi-tors are specific for a given monomer, care must be taken thatany inhibitor added to the monomers is the same as thatoriginally used by the manufacturer. All the inhibitorsare commercially available; sources are given in Appendix B.

Of the monomers designated in this section for FHWAapplication, only methyl methacrylate is classified as a

flammable liquid (because the flash point is <.27 C) by the

Interstate Commerce Commission (ICC) . Although less hazard-ous, the other monomers are nevertheless combustible materialsand they should be treated as such.

Monomer handling areas should be well ventilated.All tanks and hose connections must be grounded for the safedischarge of static electricity,' and explosion-proof motorsare required. Fires involving monomers can be safelyextinguished with foam, dry powder, or carbon dioxide.

If monomer has been spilled it can be rendered safe fordisposal by covering it with a suitable absorbing agent,such as sand . Some absorbing agents such as untreated claysand micas will cause an exothermic reaction that migntignite the monomer.

Finally, a few words about catalysts and promoters. Thecatalysts used for this work are organic peroxides and shouldbe kept in a cool place, away from heat or any source ofsparks. They should be stored separately, away from monomerand in particular away from promoters or other oxidizingmaterials. Inventories should be kept to a minimum. Peroxidecatalysts have a limited shelf life and therefore lose efficiencywith time. Measurements for determining catalyst efficiencyare discussed in Chapter V.

Any catalyst accidently spilled should be swept up and

disposed of immediately. The spilled or waste catalystshould be mixed with an incombustible material such asvermiculite or perlite in amounts equal to that of thecatalyst. The mixture should be saturated with water,the excess allowed to drain off, and the wet residual masscarefully burned in an open incinerator or shallow trencn.The torch used to ignite the mass should be at least 6 ftlong, and confinement should be avoided.

9 . Monomer Curing Precautions

The preparation of monomer systems with catalysts andor promoters should be done by a person who is knowledgeable

47.

in the use of these materials. The addition of these materialsto monomers is a critical step in the preparation of polymer-impregnated concrete and polymer-concrete composites.Proper procedures will minimize any hazards involved in theuse of these highly reactive materials and will also resultin controlled polymerization. Table 3-9 lists some ofthe important DO'S and DONT'S in the preparation of catalyzedmonomer systems

.

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CHAPTER IVMETHODS OF PRODUCING POLYMER-IMPREGNATED CONCRETE

L. E. Kukacka

IntroductionThe basic method of producing polymer-impregnated concrete

(PIC), shown schematically in Figure 4-1, consists of thefabrication of precast concrete specimens, oven-drying,saturation with monomer, and in situ polymerization. Processingrequirements for each of these steps are being developed

.

A number of concrete preparation variables, such as mixcomposition, method and duration of curing, and drying tempera-ture, have been investigated to determine the effects on theproperties of the composite material. Experiments have also beenperformed to determine the process conditions required to fullyand partially impregnate various, types of concrete. Variablessuch as degree of vacuum, evacuation time, saturation time,pressure, and monomer viscosity have been studied. The effectof concrete composition on each of these parameters has alsobeen studied, and techniques for reducing monomer losses dueto evaporation and drainage during the polymerization reactionhave been evaluated . The impregnation techniques are usedin conjunction with polymerization methods involving the useof radiation, chemical-initiator, and promoter-chemicalinitiator

.

Each of these processing steps is discussed below.

1 . Concrete Preparation

CompositionA considerable amount of work has been performed to

determine the effects of concrete mix design variables on theproperties of PIC. (4*17) in these studies, compressivestrength has generally been the property evaluated . Concretemix variables investigated include water/cement ratio, entrainedair content, slump, aggregate type and quality, and the useof admixtures such as fly ash.

Data typical of those obtained by many investigators aresummarized in Figure 4-2'. They indicate that the impregnationof low-strength concrete (2000 psi) results in high-strengthPIC (25,000 psi), essentially the same as that produced fromhigh-strength samples (9000 psi) . Concretes containingnormal-weight and lightweight aggregates have also beenimpregnated. All the materials produced high-strength,durable composites. (17-19) Variations in the maximumaggregate size from 0.4 to 1.0 in. did not significantly affectthe strength or durability of the composites. On the basis of

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these results it would seem that concretes prepared fromlocally available materials can be used in the production ofhigh-quality PIC.

Method and Duration of CuringThree curing conditions/ fog curing, low-pressure steam

curing (LPS), and high-pressure steam curing (HPS) , have beenstudied to determine their effects on MMA- impregnated con-crete. (3^4,18) These data, some of which are summarized in

Figure 4-2, indicate that HPS results in higher polymerloadings and generally higher strengths than those of comparablefog-cured specimens. .

'

Tests to determine the effect of moist curing time s

indicate that, for times varying between 2 and 28 days, theduration of moist curing does not significantly affect thefinal strength of PIC. These data are summarized in Figure 4-3.

Age at Impregnationh. very limited amount of work has been performed to

determine the effect of concrete age at impregnation on thestrength properties of PIC. Specimens impregnated 1, 28 and 63

days after completion of a 28-day cure and tested at a totalage of 12 days exhibited little change in compressive andtensile strengths with age. (3)

2 . Drying RequirementsThe strength and durability properties of PIC are strongly

affected by the fraction of the porosity of the cement phasewhich is filled with polymer. If maximum improvements aredesired, it is necessary to dry and evacuate the precastspecimens prior to impregnation. Drying temperatures up to250°C have been evaluated . (3,18) initial work (3) indicatedthat specimens dried at temperatures from 150° to 2 50°C, andsubsequently impregnated with MMA, exhibited a slight decreasein compressive strength with increased drying temperature.Recent work^' indicates that a drying temperature of 110°Cis not high enough to remove all the water unless drying timesare excessively long.

Based on experience at BNL, a drying temperature of 150 C

is recommended. At this temperature the drying rates arereasonably fast (^-24 hr for a 3-ft-i.d. x 6-ft-long x 4-in.-wall pipe), and a high-quality product is produced.

3 . Monomer Saturation Techniques

Full Impregnation

Experiments to determine the conditions required to fullyimpregnate concrete have shown that process parameters such asdegree of dryness and vacuum, soak pressure, and soak time allhave an effect on the strength of PIC. (5,20)

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Filling-rate measurements were made for CP concreteunder various impregnation conditions, (see Figure 4-4) .

Without prior vacuum but with the use of 100 psig pressure,the monomer loading approached equilibrium (polymer loading,6.2 wt %) after about 10 minutes. At 10 psig, equilibriumwas not achieved after 1000 minutes. The data also indicatethat holding a sample at 30 in. Hg vacuum for 15 minutes andthen soaking at 10 psig for 30 minutes was adequate to reachsaturation. At 100 psig, saturation was achieved in considerablyless time (?«9 minutes)

.

Concrete composition significantly affects the monomerfilling rate. Samples of concrete with high air and highwater contents were saturated in shorter periods tnan CPconcrete. The initial filling rate of the high air concretewas significantly higher than that of any of the other concretestested . The data shown in Figure 4-5 are for specimens havingidentical impregnation and polymerization conditions, 30 in.

Hg vacuum and 10 psig soak pressure. The plots have beennormalized for the different saturation levels measured foreach type of concrete by comparing elapsed time with percentof maximum monomer loading. On the basis of these data, it

would appear that the filling rates are directly related tothe cement phase porosity. In the case of the shale aggregate,long filling times were required, probably because of the largenumber of pores present in the aggregate.

The effect of monomer viscosity on the filling rate ofthree concrete mixes was also measured

. '5, 20) Pre-polymersolutions were prepared by dissolving PMMA in MMA untilviscosities of 20 and 70 cP were measured. These data, shownin Figure 4-6 were compared with filling data using normalMMA (0.7 cP) under impregnation conditions of 30 in. Hg vacuumand 10 psig. Specimens of concrete with a high water-to-cementratio were fully impregnated with the higher viscosity monomersolutions in 1000 minutes. After polymerization, all thespecimens had similar compresssive strengths.

The simplest type of impregnation process would consist ofsoaking unevacuated samples at atmospheric pressure. This wouldresult in partially saturated specimens and therefore somewhatlower strengths. In general, overnight soaking of dried CP-type concrete in MMA will result in filling ^70 to 80% of thevoids that can be filled by prior evacuation. Compressivestrengths in the range of 15,000 to 17,000 psi would beanticipated

.

Partial ImpregnationPartially impregnated concrete is designed for durability

rather than high strength, which permits a saving in the amount ofmonomer as compared with fully impregnated concrete . The concrete

•k

Standard concrete mix used at USBR in concrete-polymerprogram. See Ref. 1. 55

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is impregnated to controlled depths of penetration. The monomersshould effectively seal the surface and penetrate to a sufficientdepth to avoid separation of the impregnated layer and prematurefailure. Viscous monomer systems are generally used becausepenetration depths are more easily controlled, voids in thepenetrated portion remain filled, and monomer losses due to

evaporation and drainage during the time between impregnationand complete polymerization are lower. However, for fieldapplications such as the repair of concrete-lined vessels andbridge decks, low viscosity monomers such as MMA, MMA-TMPTMA,and styrene-TMTPMA are preferred, since they require lesssevere impregnation conditions.

Techniques for the partial impregnation of concrete havebeen published . (3,4,21) ^q processes, treatment of allsurfaces and of one surface, have been described. The former(see Figure 4-7) can be accomplished by soaking in lowviscosity monomers. In work of this type, dried 4-in. cubesmade from 5600 psi control concrete were soaked in monomerfor periods varying from 5 min to 48 hr . Over this periodthe polymer loading and depth of penetration showed a nearlylinear relationship with log soak time.^"'

The use of higher viscosity monomers results in a moreuniform depth of penetration and greater control

.

^ > ' Withthese materials, positive pressures are required. A soak timeof ^5 hr at 100 psig was required to obtain a 3/4-in. penetrationwith a 67.5 wt % styrene - 32.5 wt % polyester mixture,(viscosity, 10 cP) . A typical sample is shown in Figure 4-8.

Surface treatments of up to 1 in. deep from one side havebeen achieved on bridge decks.' 22 ' Simple ponding of MMAresulted in penetration to a depth of 1/4 in. in the concrete.By placing a thin layer (-^-1/4 in.) of dried fine aggregateover the surface, greater depths of penetration have beenachieved (up to 2 in.) . The aggregate is reported to actas a wick for the monomer, and thus longer soak periods (up to25 hr) are possible without excessive evaporation. It wasfound that soak times >10 hr produced a substantial polymersurface treatment. This method was recently used by the USBRto impregnate to a depth of ^1.5 in.

4 . Encapsulation Techniques to Reduce Monomer LossesCare must be taken to minimize monomer evaporation and

drainage losses from the concrete during the polymerizationreaction. Evaporation is a problem when high vapor pressuremonomers such as MMA are used . A specimen that exhibitedexcessive loss of monomer due to evaporation is shown inFigure 4-9. Monomer drainage losses become appreciable whenlow-density concretes are impregnated

.

59

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61

Figure 4-9. Surface depletion of MMA from cut sections of PIC.

62

The following methods for reducing these losses havebeen investigated. (4,17,18,20-23)

1. Wrapping of monomer-saturated specimens in polyethylenesheet or aluminum foil

.

2. Encapsulation of the specimen in a form duringimpregnation and polymerization.

3. Polymerization with the monomer-saturatedspecimens in contact with water.

4. Impregnation with monomer followed by a pre-polymerdip, wrapping, and rotation during polymerization.

Of the methods studied, underwater polymerization appearsto be the most practical for large-scale application. Pipe,beams, and prototype bridge-deck, panels have been treated inthis manner. The method has been used successfully in conjunc-tion with radiation and thermal-catalytic polymerization. (5)

If the water is saturated with monomer prior to use, very(17 1R 21}little surface depletion is observed. The results v^'^"^^'

also indicate that underwater polymerization has no detrimentaleffects on the properties and can produce specimens withhighly reproducible polymer loadings.

It should be noted that the underwater method for theradiation and thermal-catalytic process results in the formationof polymer in the water. When drained, the polymer may adhereto the walls of the impregnator and collect in valves andpiping. This problem is essentially one of design and is

caused primarily by the polymerization of nondrainable monomer..

Less polymer is formed in the thermal-catalytic process,probably because of the decreased solubility of MMA in waterat the elevated temperature. The problem can be minimized byproper design and is more than compensated for by thereduced evaporation and drainage losses.

5 . Polymerization TechniquesThere are three general methods for the bulk polymerization

of monomers currently being used in PIC. These are radiation,thermal-catalytic, and promoter-catalyst. Although the samemethods are applicable to the .in situ polymerization ofmonomers in concrete, each process must be fully evaluated totake into account the effects of drainage and evaporationlosses from the concrete during the polymerization, the safetyproblems associated with the storage and reuse of large quantitiesof monomer and catalyst, and the economics of the entire process.

63

Rad iat

i

on-Induced Polymerization

The radiation-induced polymerization of monomers in .

concrete has been performed in air and under water .* '

The principal advantage of the process is the elimination of

a catalyst* which allows essentially unlimited storage and

reuse of monomer. In addition, polymerization can beinitiated at room temperature and at a uniform rate withinrelatively thick concrete sections. Detrimental featuresinclude the high cost of radiation sources, the necessity of

massive biological shielding, and the low polymerizationrates. The latter, when combined with the radiationattenuation due to the thick sections and high density, resultsin large radiation requirements and long processing times.

Thermal-Catalytic Polymerization

The polymerization method involving the use of chemicalinitiators and heat, commonly referred to as the thermal-catalytic process, has been used extensively for preparingPIC and appears the most practical for present-day use.The process can be performed in air or under water . Severalcatalysts that have been used in this work are describedin Chapter V.

The primary advantage of the thermal-catalyticpolymerization method is that the polymerization rates are

very rapid and therefore processing times are short. Relativelysimple electric ovens, water, or raw steam can be used as a

heat source . (5* 17, 18,22,23) & disadvantage is that thechemical initiator must be dissolved in the monomer prior to

introducing the mixture into the concrete. In a commericaloperation of almost any size this will involve storing and

handling of large batches of monomer containing chemicalinitiator. Although potentially dangerous, the use ofrelatively stable azo-type initiators in conjunction withestablished safety codes can reduce the hazards to manageablelevels. (4,5) Catalyzed monomers have been safely storedat BNL and the USBR for periods >1 yr

.

Promoter-Catalyst Polymerization

The primary advantage of a promoter-catalyst system is

that polymerization can be initiated at ambient temperaturewithout the need for an external source of energy. Disad-vantages are the difficulties in obtaining predictable

64,

polymerization times and in matching the monomer saturationtime with that of the onset of polymerization.

The techniques for using promoter-catalyst systems toproduce PIC have not yet been demonstrated on a large scale. .

However, the system is being used in field applications.' ' ' ' '

In all the work the materials were mixed immediately beforeapplication. Methods of application include injection, spraying,paint brushes, and rollers. A lis* t of the promoters currentlybeing used is given in Chapter V.

6 . Monomer Handling Techniques

The handling of monomers, particularly in large volumes,requires rigid safety controls. Monomers when shipped fromthe manufacturers contain sufficient inhibitor to maintainsafety during shipping and storage . Manufacturers recommendproper storage temperatures, toxicity limits, and otherprecautions pertinent to safe handling of the monomers.

A decrease in inhibitor concentration with time orcontact with concrete indicates that the monomer is becomingunstable and may ultimately polymerize. Therefore the monomermust be tested periodically to determine the inhibitorconcentration. Inhibitor concentrations can be measured byvarious chemical and colorimetric methods, but after themonomers have come in contact with concrete, these methodsmay not give satisfactory results. A peak exotherm methodhas been used successfully to determine the inhibitor concen-tration of monomers after contact with concrete , (2 ) Thismethod consists of adding a measured amount of catalyst to a

known volume of monomer and placing the mixture in a temperaturebath. The time required for the mixture to reach a point atwhich the polymerization reaction produces a maximum temperatureis recorded and compared with a previously prepared calibrationcurve for the mixture. A typical calibration curve for theMMA-benzoyl peroxide-hydroquinone system is given in Ref. 2.

Excellent reproducibility was obtained when monomer volume,tube size, initiation temperature, and catalyst concentrationwere kept constant

.

The greatest potential hazards exist when a catalyst hasbeen added to the monomer, as in the thermal-catalyticprocessing method. In this case the catalyst concentrationis well in excess of the inhibitor concentration and rapidpremature polymerization could occur under unfavorable conditions.Catalyst concentration can also be measured by the peak exothermmethod, in which the inhibitor concentration is held constantand that of the catalyst is varied. However, the method isless reliable for determining catalyst concentration than fordetermining inhibitor concentration.

65

Many monomers have low flash points and are thereforeClass I flammable liquids, as defined by the National FireProtection Association. Precaution should therefore be takento prevent exposure to flames, sparks, or other ignitionsources. All containers should be electrically grounded.Electrical devices in areas where monomers are handled should beexplosion proof, and spark proof tools should be used.

Bulk storage vessels should be vented, and all ventsshould be protected with flame arresters. Such vessels shouldalso be provided with rupture disks properly sized so thatin the event of bulk polymerization within the vessel, thefluid can be vented rapidly and the buildup of excessivepressure prevented

.

7 . Recommendations

High-quality PIC can be made from concretes with a widevariety of compositions. For best results, the use of standard-weight concretes containing a good-quality aggregate is

recommended. With this type of concrete, high-pressure steamcuring appears to be advantageous.

For a high-pressure steam-cured, standard-weight concretecontaining a low-porosity aggregate, the following processingcycle is recommended for sections up to 12 in. thick.

1. Oven-dry to constant weight at 150 C. Drynessshould be achieved in 24 hr

.

2. Evacuate section to 30 in. Hg and maintain for30 min.

3. Introduce monomer under vacuum and subsequentlypressurize to 10 psig. Pressure-soak for 60 min.

4

.

Remove monomer

.

5o Remove and place section in water or ; for largersections, back-fill impregnator with water.

6. Polymerize monomer in situ with hot water.

7. Remove water and clean section.

66

CHAPTER V

TECHNIQUES FOR THE PREPARATION OF POLYMER-CONCRETE

J. Fontana

Polymer-concrete (PC) consists of an aggregate mixed witha monomer which is subsequently polymerized in place. Thetechniques used for mixing and placement are similar tothose used for port land cement concrete , and after curinga high-strength, durable material is produced. Processvariables studied include monomer type, aggregate sizedistribution, and polymerization method. Other topics dis-cussed in this chapter include placement and finishing techniques,the effects of additives such as coupling agents, and safetyrequirements for mixing and placement.

1 . Polymer-Concrete Fabrication Techniques

Monomer SelectionThe important considerations in the selection of a

monomer system for use in PC include cost, durability underanticipated exposure conditions, adhesion to aggregate, andideally the ability to be polymerized at ambient temperatureby promoter-catalyst techniques in a highly predictable man-ner. Low vapor pressure is also an important characteristic,since it results in reduced evaporation losses and minimizessafety problems.

Two monomer systems that have been studied extensivelyat BNL are methyl methacrylate (MMA) and polyester-styrene

.

It is expensive to polymerize MMA alone in a predictable mannerwith use of promoter-catalyst techniques, but, with thisexception, both materials in general meet the selectioncriteria listed above. The polymerization problem can beovercome by the addition of a polyfunctional monomer such astrimethylolpropane trimethacrylate (TMPTMA) to the MMA.This results in a greatly enhanced polymerization rate andproduces a cross-linked polymer with increased temperatureand solvent resistance. Based on this finding, two monomersystems, 95 wt % MMA- 5 wt % TMPTMA and 54 wt % polyester-46 wt% styrene are currently being used in laboratory and fieldtests. Polymerization conditions for these systems and severalother monomer mixtures are summarized in Table 5-1.

Mix Design

The design of a mix to optimize the properties of PCis largely accomplished by aggregate gradation to give a voidvolume that will require minimal amounts of monomer to fill

67

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the voids and to give good workability to the mix. Thiswork has been described by many authors . (4, 5,26,29) ingeneral, the aggregate should be dried prior to use. Someepoxy resins are less affected by moisture and thereforethe drying conditions are less stringent. The major mixvariables are maximum particle size, gradation, and composition.Crushed stone and natural sand and gravel are generally used.Finely divided materials such as port land cement, powderedchalk, fly ash, and silica have also been used. Test resultsindicate that aggregate type and composition do not significantlyinfluence the strength properties of the mix (29) j-,^ $ affect ";

the durability . (30) Aggregate gradation and maximum particlesize influence the amount of resin required to coat the fillerparticles and to fill the voids. Tests have indicated thatfor a well-graded filler, larger maximum particle sizesrequire less resin. Gap grading. also tends to reduce theamount of resin required. Conversely, smaller maximum particlesizes produce higher strength mixes. An aggregate size distri-bution has been developed at USBR.(5) which, when mixed with 7

to 8% MMA produces specimens with compressive strengths of^19,000 psi. Work at BNL has indicated that dense gradedaggregate mixes of the type used in asphaltic concrete (see

Table 5-2) will produce composites with a strength of ._ »

13,000 psi when mixed with 9% of a MMA-TMPTMA monomer system.The monomer content of the mix, a dependent variable, is

the minimum necessary to coat the aggregate and to fill thevoids. Excess monomer will bleed to the surface because ofthe low density relative to the density of the aggregate.Monomer concentrations ranging from 5 to 30 wt % have beenreported. The former was obtained in pipe when a compactionmethod involving pressure, vibration, and centrifugal forcewas used in conjunction with a graded aggregate and filler. (30)

Fabrication Methods

The batching, mixing, and placing techniques for producingPC are largely based on adaptation of existing equipment andmethods for producing portland cement concrete „ However,volatile and potentially explosive monomers, such as MMA,require nonsparking and explosion-proof equipment. Mixingshould be done in a closed system or outdoors in a well-ventilated area. Some of the chemicals may be irritants ortoxic and should be handled in accordance with recognizedsafe practices.

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The PC mix is cast into forms or molds in a mannersimilar to that for conventional concrete. Wood, steel, glass,and paper molds have all been used successfully. A greatvariety of mo Id -re leasing agents, such as silicone gels,vegetable oils, automobile wax, and paraffins, have also beenused

.

After placing, the mix should be consolidated byexternal vibration, rodding, mechanical pressure, or appli-cation of vacuum to remove entrapped air. The MMA-TMPTMAcomposite cannot be vibrated by using finger vibrators suchas those used for concrete. Tamping with a concrete tamperworks well and the surface can be screeded . If the largestaggregate size used is 3/8 to 1/2 in., the screeding givesa good even surface that appears to be skid resistant. Ifthe aggregate is 3/4 in. or larger, the screeding tends topull the stones to the surface and causes an uneven and veryrough surface. With the larger stone, tamping seems togive a better surface finish.

The polyester-styrene composites can be vibrated sincethe material is a sticky mass and will not separate like theMMA-TMPTMA composites. The composite closely resemblesconcrete in its workability characteristics, therefore it

can be screeded as well as troweled .

Polymerization TechniquesTwo polymerization methods are generally used to produce

PC composites. One method, commonly referred to as thethermal-catalytic process, requires the addition of a catalyst,usually in the form of an organic peroxide, to the monomer.When the mixture is heated to the decomposition temperatureof the catalyst, the polymerization reaction starts. Thedecomposition temperature varies with the type of peroxideused. In general, the polymerization rate increases withincreased catalyst concentration and temperature.

The promoter-catalytic polymerization method is generallyused for field applications, since the reaction can beinitiated at ambient temperature.

Promoters, or accelerators, are compounds that decomposeperoxide catalysts at temperatures below the critical temperatureof the peroxide. Promoters must be selected with care, sinceeach one is usually most effective with a specific peroxidecatalyst. When promoters are used to produce a room-temperaturesetting mixture, the catalyst should be added to the monomeras the last step just prior to the use. The activity of thepromoter can be attributed to its reactivity with the catalyst,as evidenced by the fact that if the two are mixed accidentally,an explosive reaction will ensue.

71

The polymerization reaction is exothermic and thereforea temperature rise occurs . The amount of heat liberated is

dependent upon the catalyst-promoter system selected . Therate at which heat is formed and the maximum temperaturereached are dependent upon volume , shape , ambient temperature,aggregate , and the catalyst system. The exotherm temperatureshould be ^90°C or higher to ensure a complete cure of themonomer

.

The MMA-TMPTMA system has been widely used in laboratoryand field experiments. The promoters used are dimethylaniline (DMA) and dimethyl-toluidine (DMT) , and benzoylperoxide is the catalyst. If the ambient temperature is ^24°C,a concentration of 1.5% DMA and 1.5% catalyst will give a geltime of ^20 min and a cure time of 45 min. If the ambienttemperature is lower, 0.5 to 1% of DMT is added to the DMA.At a temperature of 7°C, this system will set up in ^20 minand cure in <1 hr . Polymerization conditions are listed inAppendix A.

The following PC formulation has been used extensivelyin the field : 12 to 15% monomer (95% MMA - 5% TMPTMA) byweight of aggregate, 1% DMA by weight of monomer, » 5% DMTby weight of monomer, and 1.5% benzoyl peroxide by weight ofmonomer

.

The promoter and catalyst concentrations are adjustedin the field at the time of the pour to reflect changes inambient conditions. After completing the pour, a blackpolyethylene sheet is placed over the finished surface toabsorb solar energy and also to minimize evaporation losses.

The promoter-catalyst system normally used to polymerizepolyester-styrene is 0.5 to 1% methyl ethyl ketone peroxide(MEKP) and 0.75 to 1% cobalt naphthenate , This mixturegels in 15 to 20 min and cures in <1 hr . Since thepolyester-styrene ratios can be varied , the promoter-catalystmust be adjusted to reflect any changes in styrene concentrationas well as in ambient temperature conditions. If it is

desired to increase the rate of polymerization, an additionof 0.2 5 to 0.5% DMA will reduce the gel time to ^5 min andthe cure time to ^30 min

„

Additives

Additives have been mixed with the monomers to modifythe properties of the. composite. One such material was a

silane coupling agent, used to form a chemical bond between the

polymer and the aggregate. In the presence of moisture, the

72

silane hydrolyzes to form a silanol. The silanol has a strongaffinity for silica and immediately reacts with it in anaggregate mix to form a chemical bond . The organic portionof the molecule is grafted onto the silicone atom and, onaddition of a suitable monomer such as MMA, results in theformation of a chemical bond between the portion of thecoupling agent and the growing polymer chain. The covalentbond between the inorganic and organic substrates producessignificant changes in the chemical and physical propertiesof the composite.

Three of several methods that have been used for applyingsilane coupling agents to PC composites are shown in Figure 5-1.

One method consists of adding a coupling agent directly to themonomer prior to contact with the aggregate. Another methodis to wash the aggregate with an aqueous solution of a silanecoupling agent. The aggregate must be dried after washingbefore it can be contacted with monomer

.

The third method consists of exposing the aggregate tosilane vapors before contacting the aggregate with monomer.The amount of silane coupling agent required to obtain a

maximum degree of loading can be calculated on the basis ofthe total aggregate surface area. Compressive strengthsobtain for PC specimens prepared by each of the describedmethods are shown in Figure 5-1. As noted, the strengthsare higher than those obtained without the use of couplingagents. The highest strengths were obtained by using thevapor deposition method.

PC samples were made with use of a monomer mixture of60 wt % styrene and 40 wt % TMPTMA . The effects of a silanecoupling agent on the compressive strength of 3-in.-diam x6-in.-long cylinders at 21, 121, and 143°C were compared

.

The silane was added to the monomer prior to its beingmixed with the aggregate. At 21°C, the specimens containingsilane had an average compressive strength of 12,300 psicompared with 6300 psi for specimens without silane. This^2:1 strength ratio was maintained at all test temperatures(see Figure 5-2) . In all cases, the concentration of silanewas 1% of the total monomer used

.

As described earlier, the role of the silane couplingagent is to form a covalent bond between the silica and thepolymer. The effectiveness of this reaction was confirmedby solvent extraction methods. PC specimens containing PMMAwith and without silane were exposed to boiling benzene for24 hr . The PMMA in the composite without the silane completelydissolved, while the sample with the silane remained intact.

73

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Polymer-Concrete

Effects of Silane Coupling Agent on Compressive Strength

Specimens, 3-in.-diamx6-in.-long cylinders

Monomer, 60 wt % styrene - 40 wt % TMPTMAAverage polymer loading, 6.4 wt %

Specimen Silane con- Test temper- Compressive

No. centration, % ature, °C strength, psi

206 * 21 12,500

208 21 12,100

209 121 9,520

228 121 9,880

231 143 8,670

232 143 8,840

234 21 6,420

238 21 6,200

235 121 5,260

240 121 4,670

242 143 3,650

246 143 4,090

Aggregate Size Distribution

Concentration,

Mesh size wt%

170--270 6.1

40- 60 10.2

20-- 30 23.0

0.5-in. stone 60.7

Figure 5-2

75

Polymer composite materials formed with MMA are fairlybrittle. This is illustrated in Figure 5-3. Curve a, foran MMA-containing PC, indicates that the composite cannotmaintain a load once the ultimate stress is reached. Theforittleness of this material can be greatly reduced by theaddition of a comonomer such as butyl acrylate. MMA arid

butyl acrylate readily react to form a copolymer that is

relatively tough and not subject to complete failure at itsultimate stress. Additions of 5 and 20% butyl acrylate toMMA and their respective composites gave the compressivestress-strain results shown by curves b and c in Figure 5-3

.

Although there is an accompanying reduction in the ultimatestress, some applications might be better served with amore ductile material

.

2 . Laboratory Test ing of Polymer-Concrete

Compared with the extensive testing program to determinethe properties of PIC, the PC evaluation effort at BNL andthe USER has been small ° To date, only a few of the mechanicaland durability properties have been measured. (t.\

One detailed evaluation was performed at the USER

„

In the initial work, a graded sand-aggregate mix closelyapproximating that of CP-type concrete ^ ' was integrallymixed by hand with catalyzed MMA and polymerized at 70°C.The heat generated during polymerization of these specimenswas quite high, and as a result the samples developedrelatively low compressive strengths, of the order of 8000 to12,000 psic Subsequent work on the method and incrementaltemperature control during polymerization resulted in moreconsistent specimens with compressive strengths of 11,000 to12,000 psi. The addition of cross-linking and coupling agents,glass fiber reinforcement, and a change to a tert . -butylazoisobutyronitrile catalyst improved the strength to 14,800 psi.

Development of the method has continued, and in itspresent form oven-dried Clear Creek aggregate is machinemixed with the monomer system, placed in molds, and polymerizedat room temperature by the promoter-catalyst technique . Thespecimens are prepared with 7 to 8% monomer by total weightof the wet mix. Depending on the maximum size of the aggregateand the amount of cross-linking agent in the monomer system,the specimens develop average compressive strengths varyingfrom 18,400 to 20,000 psi. These mixes have produced veryconsistent specimens with individual strengths that vary<2% from the mix average

.

76

Q.

COCOUJtr

co

l 1 1 r

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J L2000 4000 6000 8000 10000

STRAIN, /xin./in.

Figure 5-3 Compressive stress-strain curves for polymer-

concrete. Curve a, MMA; curve b, 95 wt % MMA - 5 wt

% butyl acrylate; curve c, 80 wt % MMA - 20 wt % butyl

acrylate.

77

Specimens prepared with use of conventional concrete

_ng procedures and room-temperatuie polymerization have

been tested for compressive stress-strain, tensile splitting,

unit weight and specific gravity, and water absorption (see

Table 5-3) . Other specimens were exposed to a 5% H2SO4solution for two months without any apparent effect on theirproperties

.

Creep tests have also been performed on PC specimenscontaining MMA . The tests were conducted using 6-in.-diam x12-in.-long cylinders that were subjected to compressivestresses of 800, 1301 and 3938 psi for 63 days. Thestresses were ^5, 8, and 24%, respectively, of the ultimatecompressive strength. After 63 days the specimens exhibitedless creep than normal-weight concrete. The unit creepdeformation (giin./in./psi) of PC specimens under the 3938psi compressive load was very close to that of unimpregnatedCP-type concrete under a compressive load of 2313 psi.

PC development work at BNL has been focused primarilyon highway applications such as repairing holes or as animpervious overlay on bridge decks. Criteria consideredessential for these applications are the ability to be mixedand placed conventionally, rapid predictable polymerizationrates over a wide range of temperature, high strength, andgood bonding

.

Several studies were performed to select aggregate sizedistributions that will produce high strength - low porositymaterials. To date, the best results have been obtainedusing a dried dense graded aggregate mix used on Long Islandin asphaltic concrete . A sieve analysis of this materialwas given in Table 5-2

»

Experiments were performed with the MMA-TMPTMA andpolyester-styrene monomer mixtures. The results indicatethat high-strength materials (compressive strengths >10, 000psi) with low water absorptions (<0.5%) can be producedwith polymer concentrations of 9.1 wt %. The waterabsorptions are similar to those of PIC.

Shear tests have been performed to determine thebonding characteristics of PC when applied to steel orsound concrete surfaces. Two monomer systems, 60 wt % sty-rene - 40 wt % TMPTMA and 53 wt % polyester - 28% styrene -

19 wt % TMPTMA, were used to produce PC, which was appliedas 3/4-in. -thick liners on 6 and 8-in.-diam steel pipe»A shear strength of 1100 psi was measured for PC applied tosand-blasted steel surfaces, and 400 psi was obtained forsamples that had not been sand blasted.

78

PROPERTIES OF POLYMER COHCRETE

6-inch by 12- inch cylinders

Test Temperature Result

Compress ive Strength * -15*F 24,800 psi

70*F 19,600 psi

120*F 15,800 psi **

190'F 1U,100 psi

Tensile Splitting * -15*-F 1,510 psi

TO*F 1,^30 psi

190#F 1,370 psi

Modulus of Elasticity * -15*F 6.11 x 10 psi

70*F 5.28 x 10 psi

190'F k.hk x 10 psi

Poisson's Ratio * -15*F 0.2^

70*F 0.23

190*

F

0.22

Unit Weight * — IU9.I lb/ft3

Specific Gravity * -- 2.^0

Water Absorption *** - -- 0.6 percent

Specimens prepared with 8-^ monomer by total weight. Monomer systemconsisted of 97-5-# MMA + 2.5-£ TMPTMA.

* Average value for 3 specimens.

** Value for single specimen

*** Average value for 2 specimens

79

Cores taken from concrete specimens containing 6-in.-thick PC overlays were subjected to shear strength measurements.Bond strengths at the PC-concrete interface of >1000 psi arenormally obtained

.

Preliminary tests have been performed to determine thecoefficient of thermal expansion for PC. PC specimenscr taining a 15% concentration of 75 wt % styrene - 25 wt %pDlyester exhibited an average value of 8.2 uin • /in . /°F

.

The coefficient is expected to decrease with decreasingpolymer concentration. Measurements made at the USBR (4)

on unimpregnated normal-weight concrete and PIC containing5 wt % styrene indicated values of 4 and 5 |iin./in./°F,respectively.

The largest laboratory tests performed to date at BNLconsisted of the pouring of a series of 4 x 4 x 1-ft slabs.This work was performed in support of the field experimentsdescribed below. Polymer-concretes containing 13 wt % of a

95 wt % MMA - 5 wt % TMPTMA monomer mix and 10 wt % of54 wt % polyester - 46 wt % styrene were used. The materialswere mixed and placed conventionally. Both systems cured in< 60 min, and practically no shrinkage was observed. Corestaken from the MMA-TMPTMA PC indicated compressive andshear strengths of 9600 and 2175 psi, respectively. Asimilar compressive strength, 9730 psi, was obtained forthe polyester-styrene PC. Water absorption measurementson both materials indicated values < 1%. Freeze-thawtesting is in progress; after 300 cycles, no deteriorationis apparent .

3 . Field Applications of PC

A large (~1.4 yd 3) PC placement was made on the Major

Deegan Expressway in New York City in December 197 3.

A 6-ft 3 skip loader was used to mix 900 lb of PC at one

time. Of this amount, 87% (783 lb) was the dense binder aggre-

gate previously described, and 13% (117 lb) was monomer (95 wt

% MMA - 5 wt % TMPTMA) . Since the temperature at the time of

the placement was ~10°C, it was decided to use 2% benzoylperoxide as the catalyst -and 2% DMA as a promoter . Anotherpromoter, DMT, was also available in case a faster cure time

was needed to prevent leakage or to overcome low ambient tem-

peratures .

The monomer mixture was made at BNL and batched in 5-gal

cans containing 29.25 lb of material. The catalyst was mixed

in cans painted red, and the DMA was mixed in cans paintedblack. The DMT and silane were taken in individually batchedquantities to be added at the job site if necessary.

80

The monomer system was delivered to the job site on the day ofthe placement. After completion of the form work and applicationof Crisco as a release agent, the placement was started at 12^p.mFor every batch of aggregate, four cans of monomer were added

.

Two cans containing the catalyzed monomer were added to two canscontaining promoted monomer. DMT was added to the promotedmonomer when it was determined that the forms leaked. Thishelped set the mixture in ~10 to 15 min and stopped the leakage.The monomer was mixed in garbage pails and then poured into themixer, which already had the aggregate in it . The PC was mixedfor ~3 min and then was placed into the form. The PC was tampedinto place around the rebars and another batch was prepared . In~1 hr, the placement was completed and the surface was screeded

.

During the screeding procedure, some of the 3/4-in.aggregate was pulled to the surface. The surface was thencovered with a black polyethylene sheet and the whole masswas allowed to cure for 1 hr . An estimate of the compressivestrength was made by using a Windsor probe, and valuesranging between 5400 and 8000 psi were obtained . The measuredcompressive strength of a cylinder cast from the mix was12,200 psi, and the water absorption was 0=4%. The patch wasopened to traffic within 2 hrs of completion of the placement.

The top and underside of the section have been inspectedon a periodic basis and no significant changes have beennoted, A news release issued by the NYS Department of Trans-portation, Region 10, is quoted.

"By the use of this extremely fast setting concretethe bridge deck was permanently repaired within a few hoursand the traveling public was inconvenienced only to the extentof having traffic on the Major Deegan disrupted for a fewhours during the non-rush-hour period of the day instead offor several days .

"

In other cases, such as on the Greenport bridge, whereplacements were made in July or August when the ambient tem-perature was ~30°C, the catalyst was mixed in the monomersystem at the job site.

Two drums of the monomer mixture were brought to thejob site. Catalyst was added to one drum and the promoterwas added to the other drum. Since the ambient temperaturewas high, the catalyst and promoter concentrations werereduced to 1.5%o For each batch of aggregate, the properamount of monomer was drained from the two barrels of monomer,mixed, and placed in the cement mixer. After mixing for ^-3 min,the PC was placed in forms and tamped . When the final placement

81

was made* sand of 20-30 mesh size was placed on top and screeded"his gave a much smoother appearance and better riding quality.

The Bridge Maintenance Crew of Region 10 has assistedBNL about 6 times in the placement of PC. They have neverprepared the monomer system, but they are efficient in themixing, placing, and finishing of PC composites. Althoughapprehensive when they first started working with thesematerials, they now have a better understanding of PC and

can see its value as a maintenance tool. This is a goodindication that, with the proper training, bridge and highwaymaintenance personnel can make polymer-concrete compositesand use them as an effective maintenance material.

4. Safety

There are certain dangers involved in the handlingand storage of the monomers, catalysts, and promoters dis-cussed above. All. precautions published by the manufacturersof these materials should be rigidly observed.

Particular care must be taken to avoid mixing promotersdirectly with peroxide catalysts because the mixture canreact explosively. Add all promoters to the monomer anddisperse thoroughly. Then and only then should the peroxidecatalyst be added .

A safer and highly recommended procedure for making PCcomposites is as follows: Divide the monomer system into twoequal parts, A and B. Add the promoter to Part A and thecatalyst to Part B. Take equal quantities of Part A (monomerwith promoter) and Part B( monomer with catalyst) . Add Part Bto Part A and mix thoroughly. Add the mixed monomer systemto the aggregate and mix until the aggregate is completelywetted. Pour into a form, compact, finish, and wait untilcompletely cured .

Monomers, catalysts, and promoters are flammableand must be handled with care. Dry chemical fire extinguishersshould be available at the working area, Open flames andsmoking should be avoided. near monomers, catalysts, orpromoters. Well-ventilated areas are required, and personnelshould wear safety glasses when working with these materials.The monomers have a disagreeable odor, and it is advisableto wear chemical respirators in the event of discomfort. Ifchemical materials are spilled, they should be soaked up withnoncombustable materials such as vermiculite or perlite andthen placed in a shallow trench and ignited with a torch froma safe distance.

II

82

If large quantities of monomer are to be disposed ofand burning is unacceptable, they can be polymerized inopen cans. The resulting polymer can be used as land fill.Figures 5-4 to 5-7 show the disposal of 10 gal of a styrene-TMPTMA monomer system using promoter-catalyst polymerization at'vlO°C. In Figure 5-4, the inner can contains the monomer andthe outer can contains ice water. Gel formation of themixture after ^-15 min is illustrated in Figure 5-5. After^50 min the polymerization is rapid and highly exothermic(Figure 5-6) . The reaction is complete after about ^60 min,

and the bulk polymer can now be disposed of as land fill.The solid polymer is shown in Figure 5-7

.

Stirring equipment should be either air-operated orof the explosion-proof Class I - Group D electrical variety.For small laboratory quantities, magnetic stirrers may beused. The concrete mixers used to form PC composites shouldhave explosion-proof electrical motors or be gasoline enginedriven.

Catalysts and promoters should be stored in cool placesaway from direct sunlight and separate from each other.Refrigerators should have any ignition sources mountedexternally. Manufacturers give minimum recommended storagetemperatures and shelf lives for all these materials.

It is generally recommended that monomers bestored at 20°C or less. At these temperatures, mostmonomers have a shelf life of ^6 mo. It has been possibleto store monomers for periods of 1 yr or more by carefullymonitoring the inhibitor concentration of the monomer. Allmonomers contain inhibitors that the manufacturers have addedto prevent spontaneous polymerization. The inhibitors actas free-radical scavengers and thus prevent free-radicalpolymerization. As an example, the MMA generally used atBNL has an inhibitor (hydroquinone) concentration of 2 5 ppm.It is stored in 55-gal drums in what is basically a blow-outshed maintained at ^15°C. Periodically (at least once amonth) , the inhibitor concentration is checked by the peakexotherm method. In this method, a known quantity of catalystis added to a given volume of monomer (generally 10 cc) andplaced in a constant temperature bath, and the peak exothermis measured as a function of time. The interval or time toreach the peak exotherm is compared with a calibration curve.If the inhibitor concentration falls below a previouslyestablished safety limit (15 ppm) , additional inhibitor is

added to the drum from which the sample was taken.

83

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A study was made of the shelf life of MMA monomercatalyzed with benzoyl peroxide , AIBN (Vazo 52) and butylazo-isobutyronitrile (A79) . In each case, 1% catalyst was used.About 1/2 liter of the monomer was mixed with the above-mentioned catalysts in glass beakers and covered with aluminumfoil. The beakers were placed in an air-conditioned roomwith a temperature of 23°C. At various times 10 cc ofmonomer was placed in a constant temperature bath at 70°Cand the time to the peak exotherm was measured. The monomercontaining AIBN showed an onset of polymerization after 10

days. The A79 and benzoyl peroxide systems remainedessentially stable for a period exceeding 23 days althoughdecreases in peak exotherm time of 10 and 21%, respectively,occurred .

^'

5 . Summary

Polymer concrete has the potential of combining thepremix characteristic of port land cement concrete withstrength and durability properties approaching those ofpolymer-impregnated concrete . Because of its premixednature, quick cure time at ambient temperature, and highstrength, polymer-concrete appears suitable for use in therepair of highway structures, where traffic conditionsallow closing of the area for only a few hours.

Field testing of materials containing MMA-TMPTMA andpolyester-styrene has been in progress for about three yearsand to date no detrimental effects have been noted. Themost severe test to date has been on a major arterial highwayin New York City, where a 3 x 10 x 1.25-ft hole through a

bridge deck was filled with a polymer-concrete containing13 wt % of a 95 wt % MMA - 5 wt % TMPTMA mixture. Poly-merization was completed within 1 hr, and traffic was re-stored 2 hr after completion of the placement. After 12 mo.

in service, no deterioration is apparent. It is hoped thatthe use of PC has resulted in permanent repair of the bridgedeck. All the work was confined to the non-rush-hour periodof the day and the traveling public was inconvenienced for

a few hours rather than for several days. With furtherexperience with PC, the repair time could undoubtedly bereduced

.

88

CHAPTER VITHE ROLE OF POLYMER IN POLYMER-IMPREGNATED CONCRETE

A. Auskern and W. Horn

Introduction

The incorporation of a relatively small volume of rigid poly-mer in the pores of concrete results in significant increases inits mechanical and elastic properties . The nominal compressivestrength of concrete (4000 to 6000 psi) is increased by factors of4 to 6 . Young's modulus is approximately doubled. Along withthese dramatic improvements in mechanical properties, the durabilityproperties of the polymer-impregnated concrete are greatly enhanced.This improvement probably results from the sealing of the concreteby the polymer from the corrosive agent. (1)

The improvement brought about by combining a relatively lowmodulus polymer (E « 0.4x10^ psi') with a higher modulus material(E fa 2 to 3x10^ psi) to give a product, PIC, with an even highermodulus (^4 to 6x10^ psi) is upon initial consideration surprising.This result suggests that a unique interaction occurs between thepolymer and the concrete

.

In an earlier work Auskern VJ; and Auskern and Horn v ' sug-gested that the role of polymer is twofold: to increase thestrength of the hardened cement paste and to improve the bondingbetween the matrix and aggregate. Manning and Hope (33) reachedsimilar conclusions. Gebauer, Hasselman, and Thomas' 34 ' in workon polymer- impregnated oorous ceramics, conclude that strength im-provements can be attributed to "mechanical reinforcing."

In this chapter the interaction between polymer and concreteis investigated in terms of composite theory. The approach takendiffers somewhat from that of Manning and Hooe, '

' and is similarto that used by Hansen.

' 3 5)

The predictions of composite theory are compared with experi-mental results, and the results are extended to include a discuss-ion of control of the fracture mode of polymer- impregnated con-crete .

1 . Polymer-Impregnated Cement and Concrete

Normal concrete consists of particles of fine and coarseaggregate dispersed in a matrix of hardened cement paste.The aggregate volume in normal concretes is around 65 to 7 0%.

The remaining volume is the hardened cement paste matrix. Sincesand and stone aggregates have very little porosity, the bulk ofthe porosity of concrete is in the cement (matrix) phase. Thepolymer in PIC must therefore be concentrated in the cement phase.

89

Porosity in cement has been studied for many years . (36-38)

For hydraulic setting materials, like portland cement and plaster

c^: par is, a large volume of porosity is inherent in the set struc-ture. This porosity derives mainly from the excess water requiredto lubricate the powders so that the material may be placed and is

called capillary porosity. The amount of capillary porosity pre-sent at any time depends on the original water-cement ratio (w/c)

and the maturity, or degree of hydration, of the cement paste.For a mature paste with W/C=0.5, the volume of capillary porosityis about 0.25 cm /g ©f dry paste. I£ the density of the cementpaste is 1.4 g/cc, the equivalent pore content is 35%. If thecement is in a typical concrete, the porosity of the concrete is

10 to 12%. If all these pores are filled upon monomer loading, aweight loading of 7 to 8% is calculated. Because of compositionalvariations, most normal concretes indicate polymer weight loadingsof between 5 and 8%. W

Polymer-filled or partially filled voids or bubbles are fre-quently observed on cut and polished surfaces of PIC^ 1 ) (see

Figure 6-1) . These may vary from large, irregularly shaped airvoids that result from entrapped air in the mix, to the much smaller(~0 .QOS-in.-dicim) spherical bubbles intentionally introduced viaair entraining agents . The entrapped air volume may be ~1% of

the concrete volume, and the entrained air volume, as much as 5% (39)

Thus for a concrete with 12% porosity computed from the cementphase, there Would be an additional 5% volume from entrained airand ~1% volume from entrapped air. The total pore volume is now18%o However, the bulk of the porosity (>65%) still lies withinthe cement phase Since the average capillary diameter for maturepastes is 0.5 microns, (38,40) most of the polymer present is in-

visible to the naked eye „ Even when viewed at a magnification of

1000, the o 5~n pores would be at the practical limit of detect-ability.

The polymer structure should approximate a negative replicaof the cement pore structure . Since the pore structure is a

three-dimensional network of connected irregular channels, ^ '

the polymer should resemble a three-dimensional fibrous network.Some time ago (2) polymer was extracted from a polymer-impregnatedcement by preferential dissolution of the cement phase. A three-dimensional fibrous network was observed (see Figure 6-2) Thefibers are estimated to be MD 2p. in diameter, which is the orderof magnitude of the pore diameters.

Auskern and Horn' ' showed a fractured surface of polymer-impregnated cement at lower magnification (x200) before and afterpolymer extraction „ These pictures are reproduced as Figures 6-3

and 6-4. The fractured surface (Figure 6-3) was relatively smoothand featureless and had no distinguishable polymer phase. Afterpolymer extraction by dissolution in acetone, the polymer-free

90.

Figure 6-1. A void in polymer-impregnated concrete lined with polymerx 250. (From Ref. 2.)

91

Figure 6-2. Polymer extracted from a cement-polymer specimen

(From Ref. 2.)

92

Figure 6-3. Fractured surface of cement-polymer viewed with scanningelectron microscope x 200. (From Ref. 33.)

93

Figure 6-4. Sample in Figure 3 after 1 hour in acetone x 200.

(From Ref. 33.)

94

surface showed considerable roughness (Figure 6-4) . This indicatedthat there was polymer in the as-fractured surface that could notbe directly detected as a unique phase. The smallest features read-ily revealed by "etching" the surface have diameters of <1 to 2 p..

At still lower magnifications (^xl) the presence of polymer is

revealed by a darkening of the cement, as indicated in Figure 6-5for a fractured polymer-impregnated cement. It is not readilyapparent why this should be, since the polymer is colorless. It

may be a manifestation of the way in which light is reflected frompolymer-filled pores

.

2 . PIC as a Composite Material

Concrete can be considered to be a composite material becauseit is a combination of a dispersed phase (the fine and coarse agg-regates) held together by a matrix phase. Since the properties ofthe fine aggregate (sand) are usually different from those of thecoarse aggregate, it is sometimes convenient to consider the com-posite as a coarse aggregate dispersed in a mortar matrix.

The mortar is also a composite system, consisting of a finedispersed phase in the hardened cement matrix. From a knowledgeof the properties and concentrations of the matrix phase, fineaggregate, and coarse aggregate, and with use of the appropriatecomposite model, the properties of concrete can be derived by firstcombining the cement and sand to form the mortar and then addingthe coarse aggregate to the mortar matrix. Hansen v ' has usedthis approach.

The material becomes more complex when polymer is added tothe system. The polymer fills the pores of the hardened cementpaste phase, which creates still another composite material, thehardened cement paste - polymer system. Polymer-impregnated con-crete can then be considered a composite of coarse and fine agg-regate in a matrix of polymer-impregnated cement. The problem incomposite theory is then to predict first the properties of cementwhen it is polymer-impregnated, then the properties of the compos-ite formed when fine and coarse aggregates are added to the polymer-impregnated cement matrix.

Significant progress has been made in composite theory andcomposite materials development in the past few years, mainly be-cause of the quest for high-performance lightweight materials foraerospace applications. Most of these advances have been in thearea of fiber-reinforced materials. Theoretical aspects for thistype of composite are well developed .

* ' The theory is less welldeveloped for particulate systems, such as concrete. However,several workers have developed composite models based on thestructure of concrete. ^ ' One such recent concrete model is dueto Hobbs, ^^' and is a special case of a more general solution

95

Figure 6-5. Fractured polymer-impregnated cement specimen. The dark

region is polymer filled x 2. (From Ref. 2.)

96

derived by Haskin and Shtrikman.

(

44 ) Hobbs's model will be usedhere., since it does not give results significantly different fromthose of other workers and is convenient to handle. Manning andHope ' ' used Counto's model.

Hobbs's model can be put into the form

£ - i +2V

a(r " 1} (1)

E (r + 1) - V (r - 1)m a

where E = Young's modulus of the composite,

E = modulus of the matrix,m

V = volume fraction of aggregate,a

r = E /E , where E is the modulus of the aggregate phase.am a ^ r 3 c

Equation (1) was derived for particulate composites. Asshown earlier, impregnated composites are not particulate; thepolymer assumes the structure of the continuous intersectingthree dimensional pore network. Krock * ' compared dispersedparticle and continuous-skeleton metallic composites of the samecomposition and concentration range. He observed no significantdifference in the modulus of elasticity of the two different com-posite structures. Equation 1 will therefore be used to predictthe modulus of polymer-impregnated cement. To apply Eq . (1), Em ,

the modulus of pore-free cement must be known. There are a numberof ways in which this can be estimated „ In certain cases Eq. (1)

can be used with r = and Va = Vp , the volume of porosity. Thismodel gives results similar to the MacKenzie model (46) f0r theeffect of porosity on modulus, where the modulus varies approxi-mately as (1 - Vp) 2

. However, Helmuth and Turk^4 ') have shownthat the modulus of cement varies as (1 - Vp )^.

A hardened cement paste containing about 40% porosity wasprepared o The Young's modulus was lxlO6 psio Applying therelationship of Helmuth and Turk^47 ' results in Em = 4.6xl0 6 psifor a hypothetical pore-free cement. By using this value for Emin Eq . (1), the modulus of the polymer-filled cement can becomputed. For this example the computed composite modulus is 2.3xlO psi. Experimentally a modulus of ^2.8x10° psi for the com-posite, compared with the unfilled modulus of lxlO6 psi, is ob-served. Thus, from both theoretical and experimental considera-tions, it is seen that incorporation of the rigid polymer into theporous cement phase results in a cement phase of greatly increasedstiffness

.

Equation (1) can also be applied to mortars. The aggregatephase now consists of sand particles of modulus ^10x10" psi, andthe matrix is either normal cement of modulus 1x10^ psi or

97

polymer filled cement of modulus 2.8x10 psi. The moduli of the

two mortars can be calculated for various aggregate loadings.This is illustrated in Figure 6-6 , where the theoretical curvespredicted from Eq (1) are presented along with Young's modulusfor a series of normal and polymer-filled mortars with sand con-tents ranging from 40 to 65 vol %. The calculated results are in

fairly good agreement with the experimental results, although theagreement appears better for the polymer-filled series. These re-sults indicate that for mortar the only effect of the polymer is

to increase the modulus of the cement phase.Some concretes were next investigated by adding -3/8+4 mesh

limestone aggregate to mortar in concentrations of 10 to 50 vol% The expected moduli of the concretes were calculated from Eq.(1) by using 8x10^ psi as the modulus for the limestone aggregate(estimated from sonic velocity measurements) and the observedmodulus of the 40% sand mortar. These results are shown in Figure6-7 . Here the experimental results lie below the calculated curvesand indicate an extrapolated mortar modulus (0% aggregate) lowerthan that used for the calculation. The reason for this discrep-ancy is not clear o The results do, however, have some interestingfeatures that are pertinent to composite theory. For the unfilledconcrete there is very little compositional dependence of the modu-lus o The polymer-filled concrete indicates a compositional depen-dence of approximately the proper magnitude. This suggests thatcomposite action is occurring for the polymer-filled concretes andis not occurring for the unfilled concretes. That is, for the un-filled concrete, advantage is not being taken of the relativelyhigh aggregate modulus . This usually happens when there is poorbonding between matrix and aggregate phases. Thus the presence ofpolymer appears to improve the bonding between the matrix and agg-regate .

In another test concrete, the limestone aggregate used previ-ously was replaced by steel (modulus, 30xl0 6 psi) . Equation (1)

predicts a composite modulus, for 40 vol % steel aggregate, ofabout 8xl06 psi for the unfilled concrete » Measurements indicateda modulus of 7.0 to 8.2xl0 6 psi for the polymer-filled concrete,in very good agreement with the predictions. For the unfilledconcrete the agreement was very poor. An experimental modulus of^1x10° psi was indicated.- These results again suggest that in theunfilled concrete advantage is not being taken of the high aggre-gate modulus

.

The measurements so far show that polymer-impregnated concretesbehave more like composite materials than do normal (unimpregnated)concretes. Normal mortars, however, do indicate composite action,which must arise through better bonding between the matrix andsmall sand particles. Thus it seems that the presence of the poly-mer serves two functions . The modulus of the matrix phase is in-creased, and bonding between the matrix and coarse aggregate is

98

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.

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improved. So far, composite theory has been applied to predict-ing Young's modulus of normal concrete and PIC. The fracture modeand the strength of PIC are next discussed.

3. Fracture Mode of PIC

The fracture of normal concrete has been studied in detailby many investigators. Shah and Winter '^8) have demonstrated thatin compression the mortar-aggregate interface is first to fail.The progressive failure of this interface and the enlargement andjoining of cracks lead to the significant inelasticity of concreteand the typical curvilinear stress-strain curve.

It was reported earlier (32) that the fracture modes of con-crete and PIC are different. This is illustrated in Figure 6-8,

where PIC and normal concrete are shown after failure. PIC shat-ters on failure. The fracture surfaces pass through the aggregateparticles, and thus the matrix-aggregate bond strength is greaterthan the strength of the aggregate. Stress-strain curves for nor-mal concrete and PIC are shown in Figure 6-9. PIC shows nearlylinear behavior to failure, which is typical of brittle material.

The brittle nature of PIC presents a design limitation. It

would be desirable to modify this behavior to produce a materialwith the slow failure mode of normal concrete while retaining thehigh strength and modulus of PIC.

One approach to this problem is to adjust the matrix-aggregatebond so that the failure mode, as in normal concrete, becomes fail-ure of this bond. In principle this can be done by using a verystrong, tough aggregate. If the aggregate is strong enough, animpinging crack will be diverted around the aggregate rather thanthrough it . (49) This is essentially the condition with the PICprepared with steel aggregate (see previous section) . The stress-strain curve for this material is shown in Figure 6-10. The fail-ure mode is no longer brittle, but much like that of normal con-crete. At 1% strain the material still supports >60% of theultimate load . Fractured steel aggregate concretes are illustratedin Figure 6-11.

The fracture mode of PIC can also be altered from a brittleone to one like that of normal concrete by incorporating a smallquantity (^1 vol %) of fiber in the matrix. The fiber does notaffect the modulus of the concrete because the concentration is solow. Some experiments were performed on a mortar containing 1%steel fibers (1/4 in. long by 0.010 in. in diameter). The stress-strain curve for this material is also shown in Figure 6-10. At1% strain the material still supports ^80% of the ultimate load

.

The fibers obviously serve to inhibit crack propagation throughthe mortar by providing an energy-absorbing mechanism that is wellbonded to the matrix. ' '

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Control can be exercised over the PIC fracture mode eitherby controlling the relative interface-aggregate strength or byproviding an energy-absorbing mechanism along the fracture path.Thus the brittle fracture of PIC can be readily changed to one ofconsiderable ductility without sacrificing the desirable strengthproperties of the material.

4 . Strength Improvement of Polymer-Impregnated Concrete

The strength of brittle materials can be predicted by usingthe theory that Griffiths developed in 1920 (51) for the strengthof glass. This theory states that

a - » (^ (2)

where or. is the fracture strength, A is a geometric factor, andE is Young's modulus; y is the fracture energy, or the work re-quired to create a unit area of new fracture surface; C is theintrinsic flaw or crack length, or the flaw that under stresseventually grows into the failure crack.

Inspection of the Eq . (2) tells us that the stress to pro-pagate an existing flaw increases with increasing modulus. Thishas been widely established for concrete. It also seems reason-able that the strength increases with the work of fracture for a

brittle material. The smaller the flaw size, the more difficultit will be for the flaw to propagate, and the stronger the mater-ial will be .

The Griffiths approach has been used to explain the strengthincrease of hardened cement paste when it is polymer impregnated . (52)

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yu can be measured . Then, assuming that the flaw length remainsunchanged on polymer filling, o±/ou> which is the factor by whichthe strength of hardened cement improves on polymer filling,can be computed

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The strength improvement factor was calculated for hardenedcements over a range of porosities, and is shown in Figure 6-12,in which data on partially filled cements (32) and estimatedstrength improvements for partial loadings are also given. It is

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obvious that the higher the porosity the greater is the strengthimprovement. This arises from the greater amount of polymer incae system and its very high fracture energy. For hardened cementsof -^30 to 50% porosity, a range generally encountered in normalmanufacturing, the strength upon complete polymer filling increasesby a factor of about 3 to 6. If the strength of the unimpregnatedhardened cement as a function of porosity is known, the strength ofpolymer filled vs unfilled hardened cement paste can be plotted.This is done in Figure 6-13 with use of the relationship (31 *32)

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It remains to extend this work to predict the strength improve-ment of concrete when PIC is formed. For this calculation thefracture energies of unimpregnated and impregnated concrete are re-quired, and these are not known. These values could be estimatedif the fracture energy of the aggregate were known . Some measure-ments of the fracture energy have been reported for quartz andfeldspar minerals.^ 2 ) These values are around 3 x 10^ erg/cm2 ,

which is about half that for the fracture energy of polymer-impreg-nated hardened cement paste. For PIC, YPIC i s estimated from a

simple mixing rule, ^ assuming a two-phase system. Since failurein normal concrete does not usually involve aggregate, Yc (tnefracture energy of normal concrete) is assumed to be the same asthat of hardened cement. Experimentally,^' and from compositetheory considerations, * ' the modulus of concrete increases by a

factor of 2 to 3 upon polymer impregnation. Putting these factorsin Eq. (3) results in a strength improvement of 3 to 4 times.In view of the simple assumptions made and the lack of good experi-mental values, the calculated strength improvements seem reasonable.

The improvement in strength of concrete upon polymer impreg-nation is a direct result of the increase in the elastic modulusand the fracture energy of the materials when polymer-impregnatedconcrete is formed . These improvements are a direct result of theincrease in the elastic modulus and fracture energy of the hardenedcement paste phase, and of the improved bonding between the matrixand aggregate phases

.

It is also obvious that the stronger the initial cement orconcrete, the smaller will be the improvement after polymer fill-ing. This is due to the dual role of porosity. The more porositypresent the weaker is the material, but the more polymer it cancontain, the relatively greater the strength improvement. There

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110

CHAPTER VIIQUALITY CONTROL AND NONDESTRUCTIVE TESTING

OF POLYMER-IMPREGNATED CONCRETEAllan Auskern

Introduction

In normal concrete construction a large variety of testingtechniques are used for the purpose of ascertaining whether ornot the concrete meets specifications. With the development ofpolymer-impregnated concrete (PIC) and the interest in it., es-pecially for precast applications, it is important to knowwhether this material also meets specifications.

The starting material in the preparation of PIC is a curedand dried concrete . PIC results when the pores of this materialare filled with a monomer, which. is subsequently polymerized.This process results in significant increases in strength pro-perties (generally by factors of 3 to 5) and the elastic proper-ties (Young's modulus generally increases by a factor of &2) .

A number of the testing techniques used for quality controland nondestructive testing of normal concrete have been appliedto PIC. Usually measurements were made on normal concrete andthen on PIC prepared from the same specimen. Testing was limitedto specimens of a size that could be conveniently handled in alaboratory, although some testing of more massive structures wasdone . The magnitude and types of changes observed are noted andattempts are made to correlate these with polymer loadings andphysical properties. Nine methods considered are as follows:weight change, gamma radiography, neutron radiography, modulusmeasurements, resonant frequency measurements, impact hammer,sonic velocity, coring, and Windsor probe measurements. Thiswork has been reported in the annual reports on the Concrete-Polymer Program (1-5)

.

Testing Methods

The various quality control and non-destructive testingmethods are discussed below.

1 . Weight change .

Initially polymer loadings were determined by weighing thesamples before monomer loading and after polymerization. Theprocedure is convenient for samples of reasonable size. In gen-eral, weight increases of about 5 to 1% are found. The methodevaluates the whole sample, but it does not detect variations inpolymer loading within the sample. It also weighs any unpoly-merized monomer and is unsuitable for field operation or forheavy pieces.

Ill

2 « Gamma radiography .

Gamma radiation, which is attenuated by concrete, has been usedto determine the thickness and density of concrete to accuraciesapproaching 2% for thick slabs. However, the attenuation by poly-mer is small o The decrease in radiation intensity of an incidentgamma beam passing through PIC is only about 1% greater than thatfor normal concrete. In addition, the technique cannot distin-guish between monomer and polymer.

3

,

Neutron radiography .

Neutron radiography should be a promising technique becauseof the high hydrogen content of organic polymers. Computationsfor PMMA-impregnated concrete indicate that neutron attenuationis 50 to 70% greater than for unimpregnated concrete. Consequent-ly some unimpregnated, partially impregnated, and fully impreg-nated concrete samples were examined by neutron radiography.

Two neutron radiographs are shown in Figure 7-1. Polymer-impregnated samples should appear lighter than unimpregnatedsamples. This was observed in the radiographs, but because of theoverlapping and extensive neutron shadows of the stone aggregate,meaningful radiographic density measurements could not be obtained.This technique also cannot distinguish monomer from polymer, orwater from MMA . However, the method appears to have potentialusefulness for observing gross variations in polymer contentwithin a single sample. The technique would probably be moresuccessful with mortars or small aggregage concrete

.

4. Modulus of Elasticity or Stiffness .

When PIC is formed the modulus increases significantly;therefore, techniques that subject the test specimen to a mech-anical load should indicate a reduced deflection. Attempts weremade to correlate Young's modulus and the compressive strength ofPIC cylinders. When plotted, the data from many series of diff-erent concretes, polymers, and drying and curing treatments showconsiderable scatter. Within individual groups the results aremuch more consistent. It is widely recognized that the modulusis related to the strength of concrete. This relationship appearsto be continuous between normal concrete and PIC (see Figure 7-2)

.

Modulus or deflection measurements have two important advan-tages: they reflect the average condition of the whole sample,and they are not confounded by the presence of unpolymerizedmonomers or water.

This method is also readily adaptable to continuous bridgeand highway testing. A number of commercial systems have beendeveloped in which loading devices attached to trucks movingalong the pavement automatically measure deflect ion „ AlthoughPIC structures have not been tested in this manner (nor have PC-repaired bridge decks), this technique appears appropriate forevaluating the changes brought about by polymer-impregnating thepavement surface

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5 . Resonant Frequency Methods .

ASTM test C 215-60 describes the equipment and proceduresfor measuring the resonant vibration frequencies of normal con-crete beams. The frequency at which a beam resonates is relatedto the elastic moduli of the beam. From the dimensions, weight,and resonant frequency, the various moduli can be calculated .

(55)

The procedures described in ASTM C 215-60 were evaluated for usewith PIC and worked very well. The increased modulus of PIC wasreflected in an increased resonant frequency. The procedure'sadvantages are similar to those for measuring the elastic modulus:it sees the whole sample, and it is not sensitive to monomer orwater. However, the standard instrumentation for this test is

not readily adaptable to field work, nor is the technique ingeneral suitable for large samples. Consequently a new instrumentfor determining the resonant vibration frequencies, based on theacoustic impact principle, was adapted from a commercial source. ^"'

In the acoustic impact principle the body under test is made tovibrate by continuously striking it with a hammer. The vibrationspectrum of the mass is detected with a piezoelectric accelerometercoupled to a sonic analyzer. The testing unit is pictured inFigure 7-3, and a frequency spectrum is shown in Figure 7-4.

The upper limit on the size of sample that can be vibratedhas not been determined. However, it appears that signals can bedetected through thick walls but, because of the nonideal geometry,would have to be correlated with the modulus. It also appears thatsignals whose meaning is not completely understood can be obtainedby striking and detecting massive concrete from the same surfacerather than through the thickness. This implies that the regionunder impact has been set in vibration. Although this techniqueholds promise as a simple, rapid, and inexpensive procedure, morework on massive concrete must be done to evaluate it

.

6 . Schmidt Hammer .

The Schmidt impact hammer is an instrument commonly used inthe field for nondestructive testing of concrete. The hammer,basically a sclerometer, measures hardness by impacting a steelrod against the test surface and measuring its rebound . Therebound number is considered indicative of the quality (i.e.,

strength, durability) of the concrete; the higher the reboundnumber, the higher the quality. An approximate correlation be-tween rebound number and strength has been observed . For com-pressive strengths from 3000 to 8000 psi the rebound number variesfrom about 30 to 50, depending upon the orientation of the hammer.

Initial work with the impact hammer (type N) established thatthe rebound number varies with polymer loading. This is shown inFigure 7-5 for a series of 3-in.-diam. x 6-in.-long 5000-psi con-crete cylinders. Each point is the average of five rebounds, andthe results indicate a 65% increase in rebound number for fully

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impregnated PIC compared with un impregnated concrete. Theincrease is not linear with loading, but is S-shaped, the func-tion being least sensitive for low- and high-polymer loadings.

A series of 8000-psi 6-in.-diam. x 12-in.-long concretecylinders was tested with the hammer. These results are shownin Table 7-1. Unimpregnated samples had rebound numbers ofabout 40, and impregnated samples averaged between 48 and 53.

Here the average increases in rebound number varied from 20 to33%. An extensive series of Schmidt hammer measurements wasmade on 19 pieces of concrete pipe of various sizes. The in-crease in rebound number with polymer loading varied from 21 to36% for unreinforced pipe and was independent of wall thickness.The rebound number increased with increasing wall thickness andappeared to level off between wall thicknesses of 2 1/2 to 3 in.

(Figure 7-6) » This probably indicates the limits of the sensi-tive range of the Schmidt hammer and suggests that the centralregions of sections with walls more than 5 to 6 in. thick areinaccessible to the Schmidt hammer.

The Schmidt hammer has certain attractive features fortesting PIC. It is inexpensive, simple, and easy to operate.The rebound number changes significantly with polymer content,and is not sensitive to the presence of water or monomer in thepores. It is best suited for relatively thin sections, since it

appears to have a limited range, which is probably dependent uponthe hammer's size,,

7 . Sonic Velocity .

Measurement of the velocity of sound waves passing throughconcrete has become one of the most powerful and extensively usednon-destructive methods for evaluating the quality of concrete.Velocity measurements have been used in the field evaluation ofconcrete for many years, and an extensive body of literature hasdeveloped

.

In general, the higher the sonic velocity, the higher is

the quality of the concrete. Concretes with sonic velocities>15,000 ft/sec are considered excellent, and those with velocities<10,000 ft/sec are considered poor. However, sonic velocitiesdiffer greatly according to type of aggregate and dryness of theconcrete

.

Since the formation of PIC involves replacing the air ormoisture in the concrete pores with polymer, it was anticipatedthat significant increases in the sonic velocity would result.Consequently measurements were made to investigate the relation-ship between sonic velocity, polymer loading, and compressivestrength

.

Most of the evaluation work was done on 3-in.-diam x 6-in.-long 5000-psi concrete cylinders. In all cases the sonic velocity

119

Table 7-1

Summary of Schmidt Hammer Tests on 6-in.-long x 12-in.-diam.Cylinders (32)

(3)

Series No. of samples Polymer loading Rebound No .

OSW-9 9

0SW-LA2 2

0SW-8S 180SW-8D 17

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* Average deviation from the mean.

control 39.8 + 1.2*control 40.64.6 53.4 + 1.84.5 53.0 + 1.34.4 51.9 + 2.35,3 48.5 + 1.1

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increased when polymer was present in the concrete. In addition,the velocity of unimpregnated concrete was quite sensitive tooisture content. As shown in Figure 7-7, for between and 1%

water content, the velocity can vary by more than 10%. The sonicvelocity of the dried sample (dried to constant weight at 125°C)was in the range for poor concrete, and that of the water-saturatedconcrete was in the range for good concrete. Thus, absolute vel-ocity measurements may be misleading, and for proper comparisonof specimens the state of dryness must be specified.

A series of compressive strength specimens was sonicallytested before and after polymerization. To permit a range ofpolymer loadings, half of the specimens were impregnated in theundried condition and half were thoroughly dried. In Figure 7-8the sonic velocities are plotted against compressive strength.The velocities of the unimpregnated samples are also plottedagainst strength

„

The sonic velocities of the undried, unimpregnated specimensranged from 11,000 to 12,000 ft/sec. Those of the dried, unim-pregnated specimens exhibited considerable scatter, ranging from7500 to 10,500 ft/sec. On filling the specimens with polymer thesonic velocities of both groups increased to about the same value,about 13,000 ft/sec, although the dried specimens contained abouttwice as much polymer (?Jo wt %) as the undried ones (3 wt %) .

Thus, the polymer content of the concrete cannot be determined,and neither, therefore, can the strength be estimated, from vel-ocity measurements alone. The results do indicate, however, thatthe specimens showing the greater change in velocity with polymerloading have higher strengths than those showing a smaller change.In Figure 7-9 the relative velocities, i,e„, the ratio of thevelocity after impregnation to that before, are plotted againstcompressive strength. Although there is considerable scatter, adefinite trend is apparent. The specimens with the higher vel-ocity ratios have higher strengths. Since these specimens arethe ones with the higher polymer content, this trend might havebeen expected o

One aspect of sonic velocity testing that has not been con-sidered in this work is crack detection. This would be especiallypromising in evaluating the repair of damaged structures.

8. The Windsor Probe .

The Windsor probe is an impact -type measurement method inwhich a projectile is fired into a concrete surface under knownand reproducible conditions. The pentration depth is consideredto be inversely proportional to the strength of the concrete.While no work has been done with the Windsor probe on PIC at BNL(some field testing has been done on PC ^"7'), it is mentioned asanother possible technique. It is quite likely that the greater

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strength of PIC, as compared with normal concrete, would be re-flected in significantly less penetration of the PIC materials.

9. Coring .

The taking and testing of cores, while not nondestructive inthe full meaning of the word, gives results with which it isdifficult to argue. it is the standard procedure at BNL for eval-uating polymer-treated bridge decks and roads. The procedure is,

of course, time consuming, expensive, and requires careful prepa-ration of the samples prior to strength testing.

Discussion

It is obvious that the quality control and nondestructivetesting techniques that are applicable to normal concrete aresensitive to the property changes that occur when PIC is formed.However, two important considerations must be kept in mind whenPIC is tested; (1) some techniques do not sense the whole samplevolume, and (2) some techniques do not discriminate between monomerand polymer.

The recommendation of a particular technique in the presentstate of the art would be premature. There has been very littleapplication of PIC in the United States. In work on bridge andhighway repairs, as mentioned earlier, coring is the procedure ofchoice. it might be valuable if coring could be combined with oneor two of the other techniques described to permit correlation ofthe various techniques.

For precast applications a number of techniques, with propercontrols, would be suitable.

Conclusions

The techniques for quality control and nondestructive testingof polymer-impregnated concrete are available but must be provedin the field. As PIC (and PC) projects are undertaken, considera-tion should be given to the use of some of the testing methodsdescribed here, or others, so that a body of knowledge can be de-veloped from which the best choices may be made.

126

CHAPTER VIIIFHWA PROGRAMS ON POLYMER-IMPREGNATED CONCRETE

L. E. Kukacka

Introduction

One of the most severe problems facing the highway industryis the rapid deterioration of concrete bridge decks and other high-way structures. It has been estimated that more than $70 millionis spent in repairing or replacing deteriorated bridge decks inthe United States each year

.

The Offices of Research and Development, Federal Highway Ad-ministration (FHWA) , consider elimination of these problems as oneof their highest priority efforts. The problems and approaches totheir solution are defined in Tasks 4-B-l and 4-B-2 of the Feder-ally Coordinated Program of Research and Development under thetitles "Elimination of Spalling and Delamination of StructuralConcrete" and "Development of Materials and Techniques for RapidRepair of Deteriorated Concrete." The research described in thischapter represents work in each of these tasks.

In 1969 the FHWA initiated research at BNL and the USBR onthe use of PIC for highway applications. There are three mainparts to the program: (1) the repair of deteriorated bridge decksby monomer impregnation, (2) sealing of new bridge decks by partialimpregnation, and (3) the design and structural testing of a systemof prestressed PIC panels for bridge decking.

In addition, several other PIC research programs are in pro-gress, including a study sponsored by the Texas Highway Departmentat the University of Texas on surface impregnation of bridge decks,work at the California Division of Highways, and a study sponsoredby the National Cooperative Highway Research Program (NCHRP) atLehigh University (Study No. 18-2, Use of Polymers in Highway Con-crete) . Descriptions of these programs are given below.

BNL Research

The experimental program at BNL consists of work in three gen-eral areas: material properties of PIC, repair of deteriorated anddelaminated bridge decks,' and partial in-depth impregnation of newdecks. The results of these studies have been published.

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The structural and durability properties of impregnated normal-weight and structural lightweight concretes have been measured.The effects of temperature and cyclic loading were investigated andbond pull-out strength of reinforcement was measured. Process vari-ables studied include monomer type, method of polymerization, andair content of the concrete. The results of these tests are summar-ized in Table 8-1. Compared with the controls, MMA-impregnated

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samples had improvement factors ranging from 2.6 to 4.5. Theuse of polymer-impregnated concrete as a means of preventingchloride penetration into bridge decks has been demonstrated.This offers a potential solution to the bridge deck deteriora-tion problem.

The feasibility of repairing highly deteriorated and delamin-ated bridge decks by monomer impregnation has been demonstratedand field testing has been in progress since July 1973. Resultsto date indicate that highly deteriorated concrete can be recon-stituted and bonded to the sound concrete beneath. Compressiveand bond strengths of 8000 and 1100 psi, respectively , have beenobtained. No deterioration of the repaired sections has beenobserved after exposure to traffic for 16 months.

During the course of the experimental program, generalizedprocedures have been developed for drying, monomer impregnation,and polymerization. Descriptions of each of these steps and howthey were performed on a highly deteriorated bridge in Greenport,N. Y. , are given below.

Drying

Adequate drying of the deck prior to the application of monomeris one of the most important procedures in the impregnation process.Moisture has two deleterious effects. It reduces the amount of por-osity in the concrete which is accessible to monomer, thereby reduc-ing the strength and durability, and reduces the bond strength be-tween the polymer and aggregate. An upper limit of 3 wt % has beenestablished for moisture content.

Drying has been accomplished with use of kerosene-fired hot-airheaters (see Figure 8-1) . Air heated to 150 C was directed into anasbestos blanket enclosure which was used to box-in the bottom ofthe deck. Three tests have been performed with the above technique.In the first test, which was severely hampered by rain, a sectionmeasuring 10 x 10 ft x 14 in. was dried to a moisture content of 3%in «5 days. In two subsequent tests the moisture content of a 6-in.-thick deck was reduced to <0.5% in 4 days (Figure 8-2) . Trafficwas maintained on the sections during the entire drying operation.

Impregnation

Prior to impregnation the underside of the bridge deck must besealed to prevent loss of monomer through cracks. This is done byapplying a coating of standard polyester resin on underside surfacesshowing cracks.

Impregnation is performed with use of a ponding technique.After covering the deck with «0.5 in. of dried sand, which servesas a wick and an evaporation barrier, a monomer mixture consisting

12 9

DRYING DATA

GREENPORT BRIDGE TEST JULY 1974

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131

of 95 wt % methyl methacrylate (MMA) - 5 wt % trimethylolpropanetrimethacrylate (TMPTMA) and containing 1% azobisisobutyronitrile(AIBN) catalyst by weight of the monomer, is applied to the sand.Saturation of the sand is continued until the deck is completelyimpregnated. Soaking for 4 days was sufficient to saturate the6-in. -thick structural deck at Greenport.

A method for containing the monomer during the soaking periodis required. At Greenport this was accomplished by using sectionsof the concrete wearing course as a dike. If the entire wearingcourse is removed prior to drying and impregnation, another dikingmaterial such as polymer-concrete or a quick-setting cement can beused.

lerization

Polymerization of the monomer is easily accomplished by useof the thermal-catalytic technique. The deck is heated to ^'70 Cwith the hot-air equipment used for the drying operation. Over-night heating is adequate to ensure complete polymerization in a

6-in. -thick deck. After polymerization a polymer-concrete orasphaltic-concrete overlay can be applied to the deck in order toobtain an adequate riding surface.

The procedures described above have been used to successfullytreat a 6 x 10-ft section of a highly deteriorated bridge deck atGreenport, N. Y. Because of the high degree of deterioration,cores could not be taken prior to impregnation. Test measurementson cores taken from the impregnated section (see Figure 8-3) in-dicated compressive strengths and water absorptions of 5000 psiand 1.6%, respectively. These results were confirmed in a subse-quent experiment. The New York State Department of Transportation(NYS DOT) is in the process of developing plans for the impregna-tion of the entire 4000-ft2 deck. Use of this technique shouldresult in a savings in cost for this project, and in addition the

NYS DOT hopes to develop the technique for use as a rapid repairmethod in areas where high traffic densities make the use of con-ventional repair methods almost impossible and repair costs pro-hibitively high.

University of Texas Research

The use of a layer of sand as a monomer reservoir and as a

means of reducing evaporation losses during the partial impregna^,tion of bridge decks was developed at the University of Texas.

In the initial work at the University of Texas, simple pondingof MMA resulted in penetration of the concrete to a depth of wl/4in. By placing a thin layer (-2£l/4-in.) of dried fine aggregateover the surface, greater depths of penetration could be achieved

132

Figure 8-3. Core specimen taken from deteriorated bridge deck afterimpregnation. Top, polymer concrete. Bottom, impregnated concrete.

133

(up to 1 in.) . The aggregate is reported to act as a wick forthe monomer and thus permits longer soak periods (up to 25 hr)without excessive evaporation. It was found that soak times>10 hr produced a substantial polymer surface treatment.

A typical treatment of a field specimen consisted of

(1) covering the specimen with polyethylene to preventrain from wetting the surface and to dry the slabs;

(2) drying the surface for several days with an electricheating blanket;

(3) removing the heating blanket and covering the slabwith J&1/4 in. of oven-dried lightweight fine aggregate;

(4) applying an initial 2000 to 3000 ml of the monomersystem to each 12 ft of surface;

(5) covering the surface with polyethylene to retardevaporation;

(6) shading the surface to prevent a temperature increase,which might initiate polymerization prematurely;

(7) periodically adding additional monomer to keep thesand moist for a minimum soak time of 8 hr; and

(8) applying heat to polymerize the monomer.

Bureau of Reclamation Research

The USBR has developed a field method for the surface impreg-nation of new bridge decks . Numerous laboratory experimentsand two bridge tests have been performed. The following treatmentcycle has been used to give 1 to 2-in. penetration depths: (1)

surface drying for 3 days at 107° to 121°C / (2) one-day cooling,(3) monomer application and overnight soaking, and (4) polymeriza-tion at 60° to 70°C.

Gas-fired heaters rated at 250,000 and 500,000 Btu/hr havebeen used to dry the concrete to the desired depth of penetration.After cooling, a 3/8-in. -thick layer of sand is spread over thesurface. A monomer mixture consisting of 95 wt % MMA - 5 wt %TMPTMA, and containing 0.5 wt % AIBN as the initiator is used tosaturate the sand. Polymerization is initiated by heating thedeck with use of the gas-fired heaters.

In October 1974 the USBR used the above procedures to treatthe surface of a new 28 x 61-ft bridge deck in a suburb of Denver.Penetration depths of up to 1.75 in. were obtained.

California Division of Highways Research

During September 1973, the BNL provided technical assistanceto the California Division of Highways for a test in which a

134

section of the Pit River Bridge, located on Route 5 near Redding,California, was partially impregnated. The experimental effortconsisted of impregnating about 2000 ft 2 of the No. 2 northboundlane. Three surface cleaning methods - sand blasting, steam, andbush hammering - were used. Dried and undried sections of eacharea were impregnated with two monomer systems, 95 wt % MMA - 5 wt% TMPTMA and 60 wt % styrene - 40 wt % TMPTMA. The monomers wereapplied by using paint rollers and squeegees (see Figure 8-4) . Insome areas a polyester-TMPTMA coating was applied to the impreg-nated surface to reduce evaporation losses. Polymerization wasinitiated by promoter-catalyst techniques. The amount of monomerabsorbed was determined on the basis of the quantities applied.Neglecting evaporation losses, values were estimated to range from0.3 to 1.0 lb/ft . The MMA system appeared to penetrate morereadily than the styrene-TMPTMA, but variations due to the type ofsurface treatment were not apparent.

Permeability and petrographic tests were performed on corespecimens removed from the treated sections. Compared with thecontrols, reductions in water permeability of a factor of 10 wereobtained. Polymer was found in all specimens, but the depth washighly variable. The maximum depth of penetration was 2 3/4 in.

There was no apparent correlation between depth of penetrationand the type of monomer or method of surface preparation.

The California Division of Highways is continuing their studyof PIC and PC materials.

USBR/Prestressed Concrete Institute Research

In 1972 the Federal Highway Administration (FHWA) initiateda research contract with the Bureau of Reclamation (USBR) for thedesign and structural testing of a system of prestressed and PICpanels for bridge decking. This study was also strongly supportedwith funds and engineering services by the USBR and the PrestressedConcrete Institute

.

This application for polymer impregnation of concrete waschosen by the FHWA as one possible solution to the problem of bridgedeck deterioration. However, in addition to utilizing the resis-tance of PIC to chemical and freeze-thaw attack, this bridge deck-ing system has the improved strength and other physical propertiesof PIC

.

PIC panels are being evaluated for use as bridge decks. Todate, 16-ft-long x 4-ft-wide x 0.5-ft-thick panels prestressed inthe longitudinal direction have been impregnated and tested todetermine their static and fatigue behavior on a simulated bridgegirder configuration. The results of the tests showed that thepanels met the design requirements.' ' A preliminary study in-dicated that this concept of bridge decking may be economical,

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.137

CHAPTER IXFIELD EVALUATION OF POLYMER-CONCRETE

L. E. Kukacka

Introduction

Preliminary field testing of BNL-prepared PC has been inprogress for about three years. Initially, several pot holes ina road leading to a receiving depot at BNL were filled withpolyester-styrene PC. Since that time, several patches have beenmade on bridges located at Sag Harbor and Greenport, New York.This work is described in Ref. 25.

On the basis of the results obtained in the preliminary fieldexperiments, PC was used in New York City to repair a badly deter-iorated section of a bridge. The work, conducted as a jointventure of the New York State Department of Transportation, theNew York City Arterial Highway Maintenance Department, and BNL,involved the filling of a 3 x 10 x 1.25-ft hole through the Thirdand Lincoln Avenues bridge of the Major Deegan Expressway in thelower Bronx (see Figure 9-1). The high traffic densities in thisarea (£85,000 vehicles/day) prevent closing of a lane for >5 hr.Since conventional repair methods could not be used, the hole hadbeen covered with a steel plate.

On December 4, 1973, one lane was closed while the form workwas prepared. The hole was filled on December 6 with a PC consist-ing of 13% monomer (95 wt % MMA - 5 wt % TMPTMA) and 87% of thedense graded aggregate described in Table 9-1. Because the ambienttemperature was J^10°C, 2% benzoyl peroxide was used as the catalyst,with a mixture of 2% dimethyl aniline and 1 to 2% dimethyl toluidineas the promoter. A silane coupling agent was added at a concentra-ion of 1.5% to enhance bonding of the adjacent concrete. Mixingand placement were completed in 1 hr with use of conventional equip-ment. Polymerization was complete within 1 hr, at which time theside forms were removed. The completed patch is shown in Figure9-2. At an age of 1 hr, estimates of the compressive strengthmade with use of a Windsor probe indicated values ranging between5400 and 8000 psi. The measured compressive strength of a cylindercast from the same mix was 12,200 psi, and the water absorptionwas 0.4%. At 3«00 p.m., 5 hr after starting work and 2 hr aftercompletion of the placement, the lane was reopened to traffic.The top and underside of the section have been inspected on a

routine basis. After 7 months in service, no changes have beennoted. Work to repair five larger holes in the bridge is

scheduled

.

Cost Estimates for Polymer-Concrete

Because the number of small-scale field tests performed to

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date is small, only the material costs associated with the use ofPC have been determined. Attempts to determine placement andtraffic control costs will be made in conjunction with future re-pair work on the Major Deegan Expressway.

Since the required formwork and the placement techniques forPC are basically the same as those used for portland cement con-crete, the installation costs should be similar. Traffic controlcosts will be significantly lower because of the shorter curetime. Future maintenance costs should also be reduced.

The cost for the materials used in the first test on theMajor Deegan Expressway was $302/yd . Of this total, $77 wasdirectly attributable to the low ambient temperature (10°C) duringplacement which necessitated the use of 1.25 wt % dimethyl toluidine(cost, $9.50/lb) in conjunction with 2 wt % dimethyl aniline ($1.50/lb)as the promoter and 2 wt % benzoyl peroxide ($1.26/lb) as thecatalyst. For temperatures >20°C, 1 wt % benzoyl peroxide and 1

wt % dimethyl aniline would be sufficient to product completepolymerization in <60 min.

Further reductions in cost can be obtained by using polyester-styrene. PC containing 10 wt % of a 54 wt % polyester - 46 wt %styrene mixture produces compressive strengths of ^10,000 psi in<60 min. Polymerization conditions for the mixture were given inChapter V. Based on a current price of 37C/lb for the polyester-styrene, the materials for this mix can be obtained for $170/yd^.

Compared with portland cement concrete, PC is expensive andas a result it will probably not be used as a general substitutefor concrete. There are, however, many specific applicationswhere the properties of concrete are inadequate. One such appli-cation would appear to be as a specialized bridge deck or pavementpatching material. For these applications, PC's high strength,rapid curing characteristics, and good durability will result inminimum traffic delays, improved safety, and in some cases mayeliminate the necessity of constructing expensive detours. Inthese cases, the material cost becomes insignificant.

142

REFERENCES

1. Steinberg, M., Dikeou, J.T., Kukacka, L.E., Backstrom, J.E.,Colombo, P., Rubenstein, S.^Kelsch, J. J., and Manowitz, B.,Concrete-Polymer Materials. First Topical Report. BNL 50134(T-509) and USBR General Report No. 41, Dec. 1968.

2. Steinberg, M., Dikeou, J., Kukacka, L.E., Backstrom, J.E.,Colombo, P., Hicky, K.B., Auskern, A., Rubenstein, S.,Manowitz, B., and Jones, C.W., Concrete-Polymer Materials .

Second Topical Report . BNL 50218 (T-560) and USBR REC-OCE-70-1, Jan. 1970.

3. Dikeou, J.T., Steinberg, M., Cowan, W.C., Kukacka, L.E.,DePuy, G.W., Auskern, A., Smoak, W.G., Colombo, P., Wallace,G.B., Hendrie, J.M., and Manowitz, B., Concrete-PolymerMaterials. Third Topical Report , USBR REC-ERC-71-6 and BNL50275 (T-602), Jan. 1971.

4. Kukacka, L.E. and DePuy, G.W., Editors, Concrete-PolymerMaterials. Fourth Topical Report. USBR REC-ERC-72-10 andBNL 50328, Jan. 1972.

5. DePuy, G.W. and Kukacka, L.E., Editors, Concrete-PolymerMaterials. Fifth Topical Report. BNL 50390 and USBR REC-ERC-73-12, Dec. 1973.

6. Steinberg, M., Colombo, P., Kukacka, L.E., and Manowitz, B.,Method of Producing Plastic Impregnated Concrete, U.S.Patent 3,567,496, March 2, 1971.

7. Wagner, H.B., Chem . Tech no 1 . 2, 105-18 (1973).

8. Emig, G.L., Latex polymer cement concrete structural proper -

ties and applications, presented at Amer . Cone . Inst . seminaron Concrete With Polymers, Denver, Apr. 1973.

9. Moshchanskii, N.A., and Paturoev, V.V., Editors, StructuralChemically Stable polymer Concretes , Izdatel'stuo LiteraturyPO Stroitel 'stvu, Moskva 1970, Translated from Russian,Israel Program for Scientific Translations, Jerusalem 1971.

10. Cowan, W.C., and Thurman, A.G., Polymer-impregnated precastprestressed concrete bridge decks, Presented at Amer . Concr

.

Inst. Symp . on Concrete Bridge Decks, San Francisco, Apr. 1974.

143

11. Steinberg, M., and Colombo, P., Preliminary Survey of Polymer-Impregnated Stone. BNL 50255, Sept. 1970.

12. Waide, C.H., Reich, M., Powell, J.R., Klamut, C.J., Colombo,P., and Steinberg, M., Mine Safety and Underground SupportStructures: Rock Impregnation and Pumpable Rockbolt Develop-ment. BNL 50402, June 1973.

13. O'Driscoll, K.F., The Nature and Chemistry of High Polymers ,

Reinhold, New York, 1964.

14. Williams, D.J., Polymer Science and Engineering. Prentice-Hall, New York, 1971.

15. Billmeyer, Textbook of Polymer Chemistry. Interscience, NewYork, 1957.

16. D'Alelio, G.F., Fundamental Principles of Polymerization . J.

Wiley, New York, 1952.

17. Kukacka, L.E., Romano, A. J., Reich, M., Auskern, A.,Colombo, P., Klamut, C.J., Pike, R.G., and Steinberg, M.,

Concrete-Polymer Materials for Highway Applications, ProgressReport No. 2. BNL 50348, and FHWA-RD-73-7, Apr. 1972.

18. Sopler, B., Fiorato, A.E., and Linschow, R., A study ofpartially impregnated polymerized concrete specimens, Amer .

Concr . Inst .' Publ . SP-40, pp. 149-72, Detroit, 1973.

19. Levitt, M., McGahan, D.J., and Hills, P.R., A comparison ofconcrete-polymer composites produced by high energy radiation,Precast Concrete , pp. 605-08, Oct. 1972.

20. Kukacka , L.E., and Romano,, A. J., Process techniques forproducing polymer-impregnated concrete, Amer . Concr . Inst .

Publ . SP-40, pp. 15-32, Detroit, 1973.

21. Steinberg, M., Kukacka, L.E., Colombo, P., Auskern, A.,

Reich, M., and Pike, R., Concrete-Polymer Materials forHighway Applications, Progress Report No. 1 , BNL 15395,Sept. 1970.

22. Fowler, D.W., Houston, J.T., and Paul, D.R., Polymer-impregnated concrete surface treatments for hiqhway bridqedecks, Amer . Concr . Inst . Publ . SP-40 , pp. 93-118, Detroit,1973.

23. DePuy, G.W., and Dikeou, J.T., Development of polymer-impregnated concrete as a construction material for

engineering projects, Amer . Concr . Inst . Publ . SP-40 , pp.35-56, Detroit, 1973.

144

24. Keeton, J.R., Alumbaugh, R.L., and Hearst, P. J., Concretepolymer composite for military underseas facilities, Tech .

Note N-1230 , Naval Civil Engineering Laboratory, PortHueneme, California, Apr. 1972. *

25. Kukacka, L.E., Fontana, J., Romano, A. J., Steinberg, M., andPike, R.j Concrete-Polymer Materials for Highway Applications ,

Progress Report No. 3 , BNL 50417 and FHWA-RD-74-17, Dec. 19 73.

26. Dennard, J.E., Jr., Resin Concretes : A Literature Review ,

Miscellaneous Paper C-72-21, U. S. Army Engineer WaterwaysExperiment Station, Vicksburg, Miss., Sept. 1972.

27. RILEM Symp., Resin Concretes . RILEM Bulletin No. 28, Sept.1963.

28. Solomatov, V. I., Polymer-Cement Concretes and Polymer-Concretes , Izadtel'stuo Literatury PO Stroitel 'stua,Moscow 1967, AEC-tr-7147, Computer translation from Russian,U.S. Atomic Energy Commission, Oak Ridge, Tennessee.

29. Bloss, D.R., Hubbard, S.J., and Gray, B.H., Development and

Evaluation of a High-Strength Polyester Synthetic Concrete ,

Technical Report M-2, Construction Engineering ResearchLaboratory, Champaign, 111., 1970.

30. Baker, C .A . , Polymer Concrete : A Chemically Inert StructuralMaterial, Presented at the Institution of Engineers' Symposiumon Concrete Research and Development, Sydney, Australia, Sept.

20, 1973.

31. Auskern, A., The Strength of Concrete-Polvmer Systems , BNL12890, Sept. 1968.

32. Auskern, A., and Horn, W., Some properties of polymer-impregnated cements anri concretes,, J. Amer . Ceram . Soc .

54 , pp. 282-5, 1971.

33. Manning, D.G., and Hope, B.B., The effect of porosity on the

compressive strength' and elastic modulus of polymer-impregnatedconcrete, Cem. and Concr . Res., _1, pp. 631-44, 1971.

34. Gebauer, J., Hasselman, D.P.H., and Thomas, D .A . , Effect of

temperature on the strength of a polymer-impregnated porous

ceramic, J. Amer. Ceram . Soc . 55 , pp. 175-6, 1972.

35. Hansen, T.C., Strength, elasticity, and creep as related to

the internal structure of concrete, iji Proc . 4th Int . Svmp

.

on Chemistry of Cement, Nat . Bur . Stand . U.S . Monogr . 43.,

Vol. 2, pp. 709-23, Washington, D.C., 1962.

145

36. Powers, T.C., and Brownyard, T.C., Studies of the PhysicalProperties of Hardened Portland Cement Paste , Bull . 22,

Portland Cement Association, 1945.

37. Powers, T.C., Physical properties of cement paste, in Proc .

4th Symp . on Chemistry of Cement , Nat . Bur . Stand . U. S .

Monogr . 43, Vol. 2, pp. 577-613, Washington, D.C., 1962.

38. Winslow, D.N., and Diamond, S., J. Mater . , 5., p. 564, 1970.

39. Woods, H., Durability of Concrete Construction, Amer . Concr .

Inst . Monogr . 4_, Chap. 2, American Concrete Institute,Detroit, 1968.

40. Auskern, A., and Horn, W., Capillary Porosity in HardenedCement Paste, J. o_f Testing and Evaluation , in press.

41. Holister, G.S., and Thomas, C., Fibre Reinforced Materials ,

Elsevier, New York, 1966.

42. Newman, K., Concrete systems, Composite Materials , Chap. 8

Leslie Holliday, Editor, Elsevier, New York, 1966.

43. Hobbs, D.W., The Dependence of the Bulk Modulus , Young ' s

Modulus , Shrinkage and Thermal Expansion of Concrete UponAggregate Volume Concentration, TRA 437 , Cement and Concrete

Association, London, Dec, 1969.

44. Hashin, Z., and Shtrikman, S., Variational approach to the

theory of the elastic behavior of multiphase materials, J.

Phys . Solids 11, pp. 127-40, 1963.

45. Krock, R.H., Some comparisons between fiber-reinforced and

continuous skeleton tungsten-copper composite materials, .J*

Mater . 1, pp. 278-92, 1966.

46. MacKenzie, J.K., Proc . Phys . Soc . London Sect . B_, .63., No. 2,

1950.

47. Helmuth, R.A., and Turk, D.A., Elastic moduli of hardened

portland cement and tricalcium silicate pastes: effect of

porosity, Highway Research Board Special Rep . 90 , 135-44,

Washington, D. C, 1966.

48. Shah, S .P . , and Winter, G., Inelastic behavior and fracture

of concrete, Amer . Concr. Inst . J. 63, pp. 925-30, 1966.

146

49. Cook, J., and Gordon, J.E., A mechanism for the control ofcrack propagation in all-brittle systems, Proc . Roy . Soc.,A 282, 508-20, 1964.

50. Flajsman, F., Kahn, D.S., and Philips, J.C., Polymer-impregnated fiber-reinforced mortars, J. Araer. Ceram . Soc,.,

54, 129-30, 1971.

51. Auskern, A., and Horn, W., Fracture energy and strength ofpolymer-impregnated cement, Cem . and Concr . Res . 4_, 785-95,1974.

52. Summers, D.A., Corwine, J., Chen, L.K., A comparison ofmethods available for the determination of surface energy,in Proc . 12th Svmp . on Rock Mechanics , 241, 1970.

53. Tazawa, E., and Kobayashi, S., in Polymers in Concrete ,

Amer . Concr . Inst . Publ . SP-40, 57, Detroit, 1973.

54. Auskern, A., and Horn, W., ibid . , p 223.

55. Whitehurst, E.A., Evaluation of Concrete Properties fromSonic Tests , Amer . Concr . Inst . Monogr . 2_> American ConcreteInstitute, Detroit, and Iowa State University Press, Ames,1966.

56. Wang, J.C., Auskern, A., and Horn, W., J. Testing and

Eval. 1, 291-94, 1973.

57. Personal communication, L. E. Kukacka, Brookhaven NationalLaboratory, 1974.

58. Fowler, D.W., Houston, J.T., and Paul, D.R., Polymer-Impregnated Concrete for Highway Applications , ResearchReport 114-1 . The University of Texas at Austin, Feb. 1973.

147

APPENDIX A

MONOMER POLYMERIZATION CONDITIONS

1. 95 wt % MMA - 5 wt % TMPTMA24°C ambient temperature1.5% benzoyl peroxide1% DMA (dimethyl aniline)1/2% DMT (dimethyl-p-toluidine)

Gel time in PC, <=s25 to 30 minCure time of PC f <«45 to 60 min

If ambient temperature goes up to 32 to 35°C / the gel time willdecrease by about 5 to 10 min. If increased working time is

needed, cut catalyst-promoter concentrations by 1/4 to 1/2%.

If ambient temperature goes down to 7 to 13°C, increase the

catalyst and promoter concentrations by 1/4 to 1/2%.

2. 50 wt % polyester - 50 wt % styrene24°C ambient temperature1% methyl ethyl ketone peroxide1/2% cobalt naphthenate

Gel time in PC, «20 to 30 minCure time in PC, ^=40 to 50 min

If ambient temperature rises to 32 to 35°C, reduce catalyst andpromoter concentration by 1/4%.

If ambient temperature goes down to 7 to 13 C, addition of 1/4%DMA will keep the gel time at #20 to 25 min and cure time at «40min.

3. 75 wt % styrene - 25 wt % polyester24°C ambient temperature1% methyl ethyl ketone peroxide3/4% cobalt naphthenate

Gel time in PC, «25 to 30 minCure time in PC, «40 to 50 min

If ambient temperature rises to 32 to 35°C, reduce the catalystand promoter concentration by 1/4% to retain «20 to 25 min geltime.

Note ;

The composition of most polyesters used at Brookhaven NationalLaboratory is 65 wt % polyester - 35 wt % styrene as received fromthe manufacturer. To make a 50 wt % polyester - 50 wt % styrenemixture, add 30 wt % styrene to the manufacturer's 65 wt % poly-ester - 35 wt % styrene mixture.

Pc

148

APPENDIX B

SUPPLIERS OF MATERIALS FOR CONCRETE-POLYMER COMPOSITES

Cost/lb, as of July 197455-gal drum (440 lb) Tank car (40,000 lb)

Methyl Methacrylate $0.38 $0.31

Rohm and Haas Co

.

465 BoulevardEast Patterson, N. J.

E.I. du Pont de Nemours & Co.Wilmington, Del.

Union Carbide Corp.Chemicals and PlasticsNew York, N. Y.

$0.40 $0.30

Dow Chemical Co.Park 80 Plaza EastSaddle Brook, N. J.

Union Carbide Corp

.

Chemicals and PlasticsNew York, N. Y.

Monsanto Chemical Co.

800 N. Lindbergh, Blvd.St. Louis, Mo.

Koppers Co., Inc.Koppers BuildingChemical and Dyestuffs DivisionPittsburgh, Pa.

Shell Chemical Corp.Industrial Chemicals Division110 West 51st StreetNew York, N. Y.

Polyester-Styrene $0.45 $0.40

W . R . Grace and Co

.

Marco Chemical Division1711 Elizabeth AvenueWest Linden, N. J.

149

APPENDIX B (continued)

Cost/lb

Diamond Shamrock Chemical Co.

Plastics DivisionCleveland, Ohio

Arco Chemical Co.

Philadelphia, Pa.

Reichhold Chemicals, Inc.White Plains, N. Y.

Rohm and Haas Co.

East Patterson, N. J.

DurezDivision of Hooker Chemical Corp.North Tonawanda, N. Y.

Cross-Linking AgentTrimethylolpropane Trimethacrylate (TMPTMA)

$2.00

Rohm and Haas Co

.

465 BoulevardEast Patterson, N. J.

Sartomer Co., Inc.Division of Sartomer Industries, Inc.Bolmar and Neilds StreetsWest Chester, Pa.

Catalysts

1. Benzoyl peroxide $1.202. Methyl ethyl ketone peroxide $2.103 . Luozo A79 $5 .25

4. Azobisisobutyronitrile (AIBN) $18.00

Lucidol Division (1,2,3)Pennwalt Corp.1740 Military RoadBuffalo, N. Y.

Reichhold Chemicals Inc. (1,2)White Plains, N. Y.

150


Cost/lb

Shell Chemicals Inc. (1,2)Houston, Texas

Polysciences Inc . (4)

Warrington, Pa.

E.I. du Pont de Nemours & Co. (4)

Wilmington, Del.

Prompters (Accelerators )

1. Dimethyl Aniline $ 3.002. Dimethyl Toluidene $16.503. Cobalt Naphthenate $ 1.30

Berton Plastics Co. (3)

170 Wesley StreetSo. Hackensack, N. J.

Polysciences, Inc. (1,2)Warrington, Pa.

Silane Coupling Agents $ 1.25

Union Carbide Corp.Chemicals and PlasticsNew York, N. Y.

Dow Corning Corp.Midland, Mich.

Inhibitors

1. Hydroquinone $ 2.002. Methyl-ethyl-hydroquinone $ 2.253. Tert .-butyl-catechol $ 1.75

Diamond Shamrock Chemical Co. (1)

Chemicals Division711 Pittman RoadBaltimore, Md

.

Eastman Chemical Products Inc. (1,2)Subsidiary of Eastman Kodak Co.P.O. Box 431Kingsport, Tenn.

151


Cost/lb

Mallinchrodt Chemical Works (1)

P.O. Box 5439St. Louis, Mo.

Dow Chemical Co. (3)

Midland, Mich.

Solvents

1. Acetone $0.152. Trichloroethane $0.20

Ashland Chemical Co. (1,2)Industrial Chemicals andSolvents Div

.

Columbus, Ohio

J. T. Baker Chemical Co. (1)

Phillipsburg, N. J.

Mallinchrodt Chemical Works (1)

St. Louis, Mo.

Monsanto Chemical Co. (1)

St. Louis, Mo.

Diamond Shamrock Chemical Co. (2)

Cleveland, Ohio

Hooker Chemical Co. (2)

Industrial Chemicals DivisionNiagara Falls, N. Y.

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