SSPC: The Society for Protective Coatings Technology Guide...

SSPC-Guide 20May 5, 2014

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SSPC: The Society for Protective CoatingsTechnology Guide No. 20

Guide for Applying Thick Film Coatings and SurfacingsOver Concrete Floors

(replaces SSPC-TU 10 of same title)1. Scope and Description

This Guide discusses techniques and procedures to

select and apply resinous coating systems over concrete floors. These thick-film systems (greater than 500 micrometers [µm] [20 mils]) include self-leveling systems, slurry systems, broadcast systems, mortar systems, fabric-reinforced systems, spray applied systems, and non-waterproofing and underlayment membranes. Application of thin-film coatings (less than 500 µm [20 mils]) and sealers, terrazzo flooring, membrane systems designed for waterproofing, and primary and secondary containment systems is beyond the scope of this Guide.

The Guide is intended for use by floor surfacing contrac-tors, owners and specifiers, and others in the coatings and surfacings industry.

2. Referenced Standards and Publications

The latest revision of the standards below should be consulted for reference:

2.1 SSPC GUIDES, STANDARDS AND JOINT STANDARDS

SSPC-AB 1 Mineral and Slag Abrasives SSPC-AB 2 Cleanliness of Recycled Ferrous

Metallic Abrasives Surface Preparation of Concrete

SSPC-Guide 12 Guide for Illumination of Industrial Painting Projects

Design, Installation, and Maintenance of Coating Systems for Concrete Used in Secondary Containment

Design, Installation, and Maintenance of Protective Polymer Flooring Systems for Concrete

2.2 INTERNATIONAL CONCRETE REPAIR INSTITUTE TECHNICAL GUIDELINES (ICRI)

No. 310.1R Guide for Surface Preparation of Deteriorated Concrete Resulting from Reinforcing Steel Corrosion

No. 310.2 Selecting and Specifying Concrete Surface Preparation for Sealers, Coat-ings, and Polymer Overlays

No. 320.1R Guide for Selecting Application Methods for the Repair of Concrete Surfaces

No. 320.2R Guide for Selecting and Specifying Materials for Repair of Concrete Surfaces

2.3 AMERICAN CONCRETE INSTITUTE STANDARDS (ACI)

ACI CT-13 ACI Concrete Terminology ACI 201.1R Guide for Conducting a Visual Inspec-

tion of Concrete in Service ACI 201.2R Guide to Durable Concrete ACI 224R Control of Cracking in Concrete

Structures ACI 302.2R Guide for Concrete Slabs that Receive

Moisture-Sensitive Flooring Materials ACI 308R-01 Guide to Curing Concrete ACI 318 Building Code Requirements for Struc-

tural Concrete and Commentary ACI 364.1R Guide for Evaluation of Concrete Struc-

tures Before Rehabilitation ACI 546R Concrete Repair Guide

2.4 ASTM INTERNATIONAL

ASTM D4060 Standard Test Method for Abrasion Resistance of Organic Coatings by the Taber Abraser

ASTM D4260 Standard Practice for Acid Etching Concrete

ASTM D4262 Standard Test Method for pH of Chem-ically Cleaned or Etched Concrete Surfaces

ASTM D4263 Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method

ASTM D7234 Standard Test Method for Pull Off Adhesion Strength of Coatings on Concrete Using Portable Adhesion Testers

ASTM D7682 Standard Test Method for Replication and Measurement of Concrete Surface Profiles Using Replica Putty

ASTM E1745 Standard Specification for Plastic Water Vapor Retarders Used in Contact with Soil or Granular Fill under Concrete Slabs

SSPC-TU 2/ NACE 6G197

SSPC-TR 5/ NACE 02203/ICRI 710.1

SSPC-SP 13/NACE No. 6

SSPC-Guide 20May 5, 2014]

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ASTM E1643 Standard Practice for Selection, Design, Installation, and Inspection of Water Vapor Retarders Used in Contact with Earth or Granular Fill Under Concrete Slabs

ASTM F1869 Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Sub-floor Using Anhydrous Calcium Chloride

ASTM F2170 Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes

ASTM F2420 Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and Insulated Hood

2.5 US Department of Transportation, Federal Highway Administration

Alkali-Silica Reactivity Field Identification Handbook

3. Definitions

Amine Blush: Surface opalescence (blush) on coating films caused by reaction of amine co-reactant with carbon dioxide and water to form an amine carbamate. This can affect adhesion of any subsequent coat if not properly removed.

Alkali Silica Reaction (ASR): The reaction between the alkalis (sodium and potassium) in portland cement and certain siliceous rocks or minerals, such as opaline chert, strained quartz, and acidic volcanic glass, present in some aggregates. [ICRI ]

Bleed Water: Water within or emerging from newly placed concrete or mortar.

Broadcast Flooring: Unfilled resins (commonly) or aggregate-filled slurries into which aggregate is scattered by a seeder or manually into the wet uncured resin or slurry which then cures with the aggregate embedded in it.

Broadcast to Saturation/Excess: The process of scat-tering aggregate into a wet matrix (see Broadcast) until no matrix wetness is observed (until no more aggregate can be embedded into the wet matrix).

Capillary: A microscopic channel on cured concrete that permits the movement of liquid water.

Carbamate: A salt or an ester of carbamic acid. Carba-mates are formed by the reaction of an amine with carbon dioxide (R2NCO2H) and are associated with the “amine blush.”

Carbonation: The reaction between carbon dioxide and a hydroxide or oxide to form a carbonate, especially in cement paste, mortar, or concrete.

Carbonate: A breakdown product of cement exposed to carbon dioxide and hydroxide or oxide. The molecular struc-ture is the simplest oxocarbon anion. It consists of one carbon atom surrounded by three oxygen atoms (CO3

-2) in a trigonal planar arrangement.

Hydration (of Cement): The reaction of water with the calcium silicate, aluminate, or aluminoferrite components of fine Portland cement grains necessary for the setting and densifying of concrete.

Keyed (Key-in): The process by which cured concrete is removed to create a termination border for a fluid-applied flooring system.

Lap Length: The length of overlapping steel reinforcing bars.

MVE (Moisture Vapor Emissions): Description of the moisture vapor that leaves the concrete slab.

MVER (Moisture Vapor Emission Rate): Measurement of moisture vapor leaving a concrete slab.

MVT (Moisture Vapor Transmission): Description of moisture vapor that passes through a membrane.

MVTR (Moisture Vapor Transmission Rate): Rate of movement of moisture vapor through a membrane.

Planarity: General evenness of a surface in an intended direction; may be a sloped or level area.

Pozzolan: A siliceous or siliceous and aluminous mate-rial that in itself possesses little or no cementitious value but that will, in finely divided form and in the presence of moisture, chemically react with calcium hydroxide at ordinary tempera-tures to form compounds having cementitious properties; there are both natural and artificial pozzolans. [ACI]

Recoat Window (Time): A period beginning at a point when a coating has dried or cured sufficiently to be re-coated and ending when the coating has reached a degree of cure that re-coating is not recommended without an additional surface preparation procedure such as the application of a bond coat or abrading the surface.

Resin: General term applied to a wide variety of more or less transparent and fusible products, which may be natural or synthetic. They may vary widely in color. Higher molecular weight synthetic resins are more generally referred to as poly-mers. In a broad sense, this term is used to designate any polymer that is a basic binder material for coatings and plas-tics. [Painting/Coatings Dictionary]

Self-Leveling Flooring: Resinous or polymer cementi-tious materials that flow out over a concrete slab to seek their own levels; they usually require termination strips rather than key-in terminations.


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Skim Coat: A thin layer of resin- or cement-based mortar used to smooth surface irregularities.

Sloping Correction: 1) An adjustment applied to a distance measured on a slope to reduce it to a horizontal distance between the vertical lines through its end points. 2) The process of installing a given pitch to a surface.

Slump: A measure of the consistency of freshly mixed concrete, mortar, or stucco equal to the subsidence measured to the nearest 1/4 inch (6 mm) of the molded specimen imme-diately after removal of the slump cone. [ACI]

Slurry Flooring: An aggregate, powder, filler, resin mix producing a flowable, but not necessarily self-leveling mixture. Slurry floor materials are usually troweled to the thickness of the largest aggregate in the material.

Soluble Alkali Ions: Substances that form charged hydroxide bases that dissolve in water.

Spalling: The chipping or fragmenting of a surface or surface coating caused, for example, by differential thermal expansion, contraction, or physical abrasion.

Tie-In: In an installation sequence, the joining of additional material to material already placed.

4. Design Considerations for Resinous Flooring Systems

The successful design, installation, and performance of a resinous flooring system depends on an evaluation of the existing surface conditions, the conditions of installation and the conditions of use. Each of these considerations will impact the selection of the surfacing system.

4.1 Background Information on Concrete and Concrete Placement: Proper design and placement of the underlying concrete are essential to the proper performance of any resinous surfacing system. Detailed concrete and concrete substrate requirements are discussed at length by ACI 302.2R, ACI 364.1R, ACI 201.2R, ACI 546R; ICRI Guidelines No. 310.1R, No. 320.1R and No. 310.2; and The Fundamentals of Cleaning and Coating Concrete, as well as a host of other standards and publications.

Concrete is mainly a mixture of Portland cement, water, and mineral aggregate, usually sand and gravel. Sometimes additives such as fly ash and pozzolans are used. The mixture cures and hardens by hydration. Water in the mix combines chemically with the cement to bind the aggregate into the rigid mass known as concrete. Although properly formulated and cured concrete is strong and rigid, it can be attacked both physically and chemically. Concrete is very strong in compres-sion but relatively weak in tension. It can and often does crack. Concrete is also fairly porous and subject to osmotic and capil-lary forces that absorb and release water. Absorbed water can freeze within the concrete and cause spalling and cracking.

Strength-gain, wear-resistance, and shrinkage properties of every concrete mix design are affected by the water-to-cement (w/c) ratio, normally expressed as the weight of mixing water per weight of cement. Concrete with a lower water-cement ratio gains more strength than concrete with a higher one, but such low ratios may be difficult to place and consoli-date properly because of the stiffness of the mix. Chemical admixtures (water reducers) are often used to increase work-ability of the concrete while keeping the water-cement ratio low. High water-cement ratios increase shrinkage cracking and reduce surface wear resistance and compressive strength.

Approximately 200 grams of water for each 1 kilogram [kg] (0.20 pounds [lb] of water for each 1 lb) of cement is required for complete cement hydration. Roughly twice that ratio, or 400 grams of water for each 1 kg (0.40 lb of water per each 1 lb) of cement, is required for mixing, because additional water is absorbed on gel pore surfaces and the cement particles should all be wetted. More water may be added to enhance work-ability when placing concrete, but any amount in excess of 180 grams of water for each 1 kg (0.40 lb per 1 lb) of cement is not required for the hydration process and may eventually leave the concrete via evaporation or as bleed water. The general mix design shown in Table 1 is an example of a mixture that will yield a suitable substrate.

An excess of water increases shrinkage and contributes

to the formation of cracks and continuous capillaries in the hardened concrete paste. The capillaries become channels for moisture movement and for intrusive and harmful chemical solutions after the cured concrete is placed in service. Wet curing will minimize development of capillary channels.

TABLE 1EXAMPLE OF GENERAL MIX DESIGN

Cementitious Content (minimum)

517 lbs/cubic yard (179.3 kg/m3)

Water-Cement Ratio (by weight) 0.40-0.45Maximum Coarse Aggregate Size

38 millimeters [mm] (1-1/2 inches)

Air content 4-6%Slump (without high range water reducers)

less than 76 mm (3 inches)

Slump (with high range water reducers)

150 to 230 mm (6-9 inches)

Compressive Strength (28 days)

35 megapascals (MPa) (5,000 pounds per square inch [psi])

Permeability lowCement options ---Water ---


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4.2 Designing Concrete Surfaces for Resinous Floor Systems: While concrete slabs should be placed in accor-dance with standard ACI practices, it is equally important that the concrete be designed to accommodate the intended end use. The tensile strength of a concrete substrate is impor-tant in concrete design. The tensile strength of concrete is approximately 10% of its compressive strength. The failure of a concrete substrate due to low tensile strength can result in a failure of any flooring or surfacing applied over it. Resinous flooring materials manufacturers generally recommend the minimum tensile strength of the concrete substrate to be 1.4 MPa (200 psi), but prefer tensile strength to be 2.4 MPa (350 psi) or greater as measured per ASTM D7234.

An effective concrete substrate should also be low in permeability and high in density. Water or liquid moves through concrete through small pores, or capillaries, in the form of vapor; always from an environment of high vapor pressure to low vapor pressure. Vapor pressure combines the effects of temperature and humidity. In general, moisture migrates from warm, humid conditions to cool dry conditions. It is the move-ment of moisture vapor within the slab—not the total quantity of moisture within the slab—that creates subsequent problems with non-permeable floor surfacings. Excess residual or free water not used in the hydration process of cement will continue to migrate out of the concrete until the moisture content of the cement reaches equilibrium with its environment. If the envi-ronment below a concrete slab is continuously wet, capillary action will pull liquid from below the slab into the slab, but moisture most frequently moves in concrete as a vapor driven by the differential in vapor pressure.

As vapor is driven through the concrete, soluble alkali ions are transmitted with it and collect at the surface. When mois-ture cycles back into the slab, concentrating the ionic solution, crystals can form which can create enough force to disbond a resinous surfacing. If undetected, the combined phenomena of MVER (see Section 5.5.1) and ASR (see Section 5.3 ) will generally result in bond failure when concrete is used as a substrate over which resinous surfacing is applied.

Providing drainage under the concrete slab helps to reduce the source of water below it. Use of vapor barriers is required to eliminate moisture sources from below the slab. The vapor barrier should meet the requirements of ASTM E1745, with a permeance of less than 0.3 perms [grains/(ft2 • hr • inHg)] as tested in accordance with ASTM E1745 Section 7. Placement of this moisture barrier should be continuous as described in ASTM E1643. ACI 302 recommends a 50 mm (2-inch) layer of granular self-draining compactible fill above the vapor barrier. If ACI 302 is followed, extraordinary measures should be taken to keep this fill dry. Water captured within the fill layer will act as a reservoir under the slab. In most cases, it is more advantageous to pour the concrete directly onto the moisture vapor barrier, and use moisture curing techniques to prevent drying shrinkage cracking. The practice of wet-curing concrete (ACI 308-92, Chapter 2), using burlap and a waterproof cover, is preferred over the practice of using curing compounds. Although excellent curing compounds are available, proper wet curing facilitates hydration without potential for chemical

interference of the curing compound with subsequent resinous system application. A water-cured, light steel troweled finish is most suitable for subsequent application of resinous systems. Any placement method, however, that maximizes surface strength is acceptable. Minimal finishing normally produces the strongest surface.

4.3 Condition Surveys of Existing Concrete Substrate: Accurate and thorough condition surveys should be performed by experienced and qualified personnel prior to specification preparation. Condition surveys will also ensure the existing specification addresses site conditions. Surveys should be carried out according to referenced standards, including but not limited to ACI 201.1R and ICRI No. 310.1R and the SSPC Concrete Coating Condition Assessment Guide.

4.3.1 Condition Assessment of Existing SubstrateA non-laboratory field inspection of the substrate should

include:• Verification of the dimensions of the substrate. • Verification of the planarity and slope. • Verification of the concrete surface strength.

A strategy should be developed for rehabilitation or removal of areas of inadequate surface strength.

• Determination of the presence of chloride, sulfate and other soluble salts. Contaminating salts are frequently present in plants and other facilities where chemicals and solvents are used.

• Determination of the presence of existing sealers, coatings or surfacings.

• Determination of moisture conditions through appro-priate concrete moisture testing

• Determination of the presence of Alkali Aggregate Reaction

• Identification of static and moving cracks• Using the MOHS hardness test to determine integrity

of the surface• Noting presence of spalls, pop-outs, aggregated

surfaces and other imperfections• Evaluating for process-based contaminationFor at least two weeks prior to application, environmental

conditions should be representative of normal operating condi-tions at the facility in order to allow the concrete substrate to reach equilibrium.

4.4 Considerations for Coating System Selection: There are many factors that influence the ideal type of resinous flooring system for a given project. The following factors should be considered to properly choose and specify the correct system.

4.4.1 Condition of Concrete Substrate: When a seam-less resinous floor covering is considered, the type of substrate and present condition should be understood and factored into the decision making process. Spalled concrete, major cracks, the type and condition of joints, or the lack of joints, uneven surfaces, corroded surfaces, improper support and stiffness,


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etc., are types of conditions that should be addressed and considered to ensure the final flooring system will perform as the customer intends.

4.4.2 Prevailing Site Conditions at Time of installation: In addition to the considerations for surface conditions, other jobsite conditions at the time of installation ultimately affect the resin-based flooring system. Some of the key site conditions to be aware of include:

• Temperature and air flow of the area where the resin-based system will be installed at the time of installation,

• Other trades that will be working in the building during installation or occupancy by the customer,

• Requirements for masking, dust control, odor control, finish protection and site access.

4.4.3 Chemical Resistance: Correctly selected and applied resin-based floorings are effective in protecting substrates from attack from many types of chemical spills. When choosing a resin-based floor to protect from chemical attack, the type and concentration of chemical exposure with the floor should be considered. In addition, the manufacturer and contractor should know the temperature of the spillage, the frequency and duration of the exposure, and the type and frequency of cleaning and emergency wash-downs.

Resistance to particular chemicals does not exclude the possibility of surface staining. Some chemicals will cause a discoloration of the resin-based flooring without affecting the integrity and durability of the system. This discoloration is purely aesthetic and its likelihood should be communicated to the owner. If appearance is a major requirement, it should be included in the project specifications and materials selected accordingly.

With sufficient drainage and housekeeping standards, excellent service life can be achieved under conditions of highly aggressive chemical spillage. Due to the wide variety of chemical products used in industry and the diversity of synthetic resin floorings, it is not practical to provide a simple guide to chemical resistance. Manufacturers should be consulted for their experiences in similar environments and with laboratory testing results.

For more aggressive chemical environments, such as secondary containment, please refer to SSPC-TU 2/NACE 6G197.

4.4.4 Wear resistance and durability: In general, the service life of a resinous flooring system is proportional to the total thickness of the applied system. A thin coating will wear quicker than a thicker slurry filled system under the same condi-tions. This service life can be affected by numerous operational factors including the level and type of traffic, frequency and type of cleaning, use of non-skid aggregates, and exposure to chemical conditions. Physical wear and abrasion resistance of coatings or flooring systems can be compared using standard-ized laboratory abrasion tests such as ASTM D4060.

4.4.5 Temperature Resistance: Resinous flooring systems are utilized in a variety of ambient and extreme temperature conditions. The performance of the system in extreme conditions will be dependent upon the rate of temper-ature change, the coefficient of thermal expansion relative to the substrate (system design), and the thermal buffering (thick-ness) of the bond interface.

4.4.6 Slip Resistance - wet or dry service conditions: Smooth surfaced resin-based flooring can be designed to produce excellent slip resistance when dry; however, these same surfaces require a texture to maintain adequate slip resistance under contaminated conditions. The heavier the degree of contaminants, the coarser the surface texture should be to retain the required level of slip resistance.

As a general rule, smoother and less porous flooring surfaces are easier to clean and coarse textured surfaces are more difficult to clean. Designing a resinous floor requires a compromise between slip resistance and ease of cleaning.

Flooring should be selected with sufficient texture to meet the specific working conditions requirements while allowing for an effective cleaning program.

4.4.7 Environmental Considerations: As the building community responds to environmental concerns through scoring systems such as Leadership in Energy and Environ-mental Design (LEED), resin based flooring systems evolve. Environmental concerns include minimizing Volatile Organic Compounds (VOCs), eliminating of hazardous chemicals, improving Indoor Air Quality (IAQ), increasing useful service life, minimizing embodied energy, using renewable resources, and recycling materials.

Seamless flooring and coatings provide a means of helping to maintain a clean environment at the site of instal-lations through the use of non-porous, cleanable, and long lasting materials.

4.4.8 UV Resistance and Color Retention: When selecting resin-based flooring materials in areas exposed to prolonged sunlight, high intensity lighting, or ultra-violet radia-tion, it is important to note that some materials will discolor over time. Some pigments and synthetic resin binders are more susceptible to this discoloration, which is purely aesthetic. If aesthetic appearance is a major requirement, care should be taken in choosing materials that do not discolor from this exposure. Refer to manufacturer’s recommendations for UV resistant or UV stable materials.

Historically, the standard colors offered were relatively limited because of the availability of pigments with the required level of chemical resistance. However, as technologies develop and color options increase, more emphasis is being placed on the aesthetic requirements of color. When installing a resin-based floor, care should be taken to control batch rotation to avoid inevitable variations in shade resulting from the manu-facturing of the materials. In addition, application techniques and environmental conditions may cause slight variations in color.


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4.4.9 Moisture Content: Moisture within the concrete substrate is an important consideration in any material selec-tion specification. More detail concerning moisture testing is included in Section 5.5.2. Specific synthetic resin systems are being designed by manufacturers to properly address moisture issues within the substrate and should be utilized when mois-ture is a concern.

4.4.10 Installation Schedule Requirements: It is impor-tant to understand the customer’s downtime requirements when selecting materials for resinous floor installation. The time required for mobilizing, surface preparation, application of the materials and subsequent cure may interfere with the customer’s normal operations. The pot-life and cure times of resin-based systems vary, and are considerations during the selection process. Resin-based flooring system technology is evolving and systems are available that allow for rapid applica-tion and cure.

4.4.11 Budget: Most flooring decisions depend on the customer’s allowable budget. A manufacturer’s creativity in designing new systems and a contractor’s abilities to stream-line the installation process help to provide the best value for the customer, and the customer should ensure the resources are available to pay for a properly installed, well designed floor. Additionally, unforeseen jobsite situations do arise and adequate contingencies should be in place to properly compensate the installer.

All of the above considerations will affect the expected cost of the installation. In general, the following factors increase the cost of the material and the system installation:

• specialized material performance requirements, including enhanced resistance to chemicals, wear/abrasion, etc.

special aesthetic requirements• number of application steps required • amount of surface conditioning/preparation necessary• amount of site remediation necessary• limitations on time available to complete installation• restrictions on available work space

5. General Surface Preparation

5.1 Physical condition of the substrate: Successful installation of problem-free seamless flooring requires a substrate that is properly prepared. Proper subfloor prepara-tion includes removal of any substances that will interfere with the initial bond or cause loss of bond after installation. Obvious surface contaminants, degraded concrete, and excess mois-ture within the concrete are all potential problems during or after the resinous floor installation. This section reviews some of the conditions that may lead to premature coating failure. Where possible, suggestions for measuring and remedia-tion are included. Remember that the product manufacturer will always provide specific subfloor preparation require-ments; those requirements are primary and should be closely reviewed and followed.

5.1.1 Surface Contaminants

5.1.1.1 Oil and Grease: Oil and grease should be removed from concrete substrates prior to subsequent surface profiling and application of any other coating or surfacing materials. If concrete removal is specified or required, remove concrete according to contract specifications.

Water-soluble or detergent-emulsifiable contaminants should be removed by scrubbing with a detergent solution as described in ICRI No. 310.2. Following the application of suitable chemical detergent solution, the surface should be scrubbed with a stiff-bristled broom, brush, or scrubbing machine. Used solution should be collected and properly disposed. The process should be repeated as necessary to achieve acceptable results.

Oils and greases that are not water-soluble or detergent-emulsifiable may be removed by use of steam. Steam should be applied over the affected area to allow oil or grease to rise to the surface. Residue should be removed and the surface should be rinsed clean. The process should be repeated until acceptable results are achieved when performing ASTM F22, Standard Test Method for Hydrophobic Surface Films by the Water-Break Test.

There are also microbial methods of removing animal fats and oils from concrete substrates. These methods may take several days to effectively remove contaminating oils and grease. It is recommended that the owner or owner’s repre-sentative provide prior approval to use these types of products as they may contaminate the facility operations.

Some surfacing manufacturers offer oil-tolerant primers, commonly referred to as direct-to-oil (DTO) primers, which can be applied after mitigating techniques described above. Job specifications or surfacing manufacturer’s instructions should be followed carefully when using these primers.

5.1.1.2. Soluble Salt Mitigation: Contaminating salts are frequently present under existing conditions in plants and other facilities where chemicals and solvents are used. Current industry standards do not specifically address extrac-tion and analysis of soluble salts in concrete, however data is evolving. Soluble salts and other similar contaminants should be removed according to project specification or as required by the surfacing manufacturer with the approval of the facility owner or owner’s representative

5.2 Chemical Attack: Chemical attack can occur because concrete is alkaline and chemically reactive. It can be attacked by mineral acids; some alkalis; numerous salt solutions; and organic acids such as fermenting liquids, sugars, and animal oils. Corrosive solutions penetrating to the steel reinforcement may be particularly destructive because the large displace-ment of corrosion products of steel can cause cracking and spalling of concrete.

5.3 Alkali-Silica Reaction (ASR): Alkali-silica reaction occurs in concrete when soluble alkali ions such as sodium and potassium react with chemically active forms of silica (usually present in the sand or gravel aggregate). The reaction


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produces an expansive gel, which absorbs a significant quan-tity of water. Expansion of the amorphous silica gel creates internal pressures within the concrete leading to paste frac-tures and deterioration of the concrete.

ASR is manifested by cracking followed by spalling, strength loss, and disintegration of the concrete matrix, which sometimes causes pop outs, fragments of concrete that break away leaving a shallow, conical depression. When the amount of alkali is greater than the amount of reactive siliceous aggre-gates the alkali silica gel may absorb water and swell, causing expansion soon after curing. This is frequently manifested after one or more years. The Federal Highway Administration has published Alkali-Silica Reactivity Field Identification Handbook, a visual ASR guide to help identify ASR. This handbook is available for download at http://www.fhwa.dot.gov/pavement/pub_details.cfm?id=800.

ASR is best determined by recognized testing agencies equipped to perform petrographic analysis. If levels of ASR have been discovered and the condition of the substrate has been determined to be treatable by removal and replacement of specified sections of concrete substrate, those sections should be removed and replaced according to contract specifi-cations or using the methods described below. If ASR has been determined to be treatable by mitigating surface treatment techniques approved by the surfacing manufacturer, those procedures should be carried out according to the contract specification or the surfacing manufacturer’s instructions.

5.4 Carbonation: Although naturally occurring in all atmospherically exposed concrete, the fine surface crazing and softening of concrete upper surfaces particularly mani-fests itself when the surface is exposed to increased levels of airborne carbon dioxide during the hardening stage. Exhaust from direct-fired heaters commonly used during cold weather increases the carbon dioxide levels, and is a leading, though not the only, cause of excess carbonation.

Generally, carbonated concrete surfaces are soft or powdery, with insufficient tensile strength to maintain substrate-bonding properties required for surfacing adhesion. Standard adhesion testing methods, described in ASTM D7234, can be used to determine concrete surface strength required by surfacing manufacturers or project specifications. A concise discussion of carbonation can be found in the chapter entitled "Condition Assessment" in The Fundamentals of Cleaning and Coating Concrete.

5.5 Moisture Considerations

5.5.1 Moisture Vapor Emission (MVE): While the building community has used the terms moisture vapor transmission (MVT) and moisture vapor emission (MVE) interchangeably, the floor covering industry has settled on the term moisture vapor emission (MVE) or moisture vapor emission rate (MVER) to characterize the process of moisture egressing from the top surface of a concrete slab. Moisture vapor emissions can cause failures in non-permeable coatings and flooring systems.

When considering any concrete moisture test method, certain caveats should be understood. The first involves the

slab itself: none of the test methods have any value at all if a moisture vapor barrier is not present beneath the slab. The second caveat involves the test data itself: test results are a reflection of conditions at the time of the test - no test has proven adept at determining future performance.

5.5.2 Testing for Moisture: There are four commonly accepted methods of identifying the presence of an adverse moisture condition within a concrete subfloor: the concrete moisture meter, the calcium chloride test, the relative humidity test, and the plastic sheet method. All four methods perform well but each has limitations that, if ignored, can result in a failed project.

It is important to note that the tests do not correlate and never will because they measure different variables. The calcium chloride test measures the amount of moisture being emitted from the slab while the relative humidity test and the concrete moisture meter measure the amount of moisture within the slab. The plastic sheet method is simply a qualitative test indicating a positive or negative moisture emissions result. As such, a calcium chloride test can yield results acceptable enough to conclude a concrete subfloor is dry and yet a rela-tive humidity test or handheld concrete moisture meter test, performed on the very same slab and run concurrently with the calcium chloride test, can indicate the presence of an adverse moisture condition.

The concrete moisture meter is an easy-to-use, non-invasive instrument for the non-destructive evaluation of moisture content in concrete. The electrodes transmit parallel low frequency signals, calibrated to give average moisture content by comparing the change in impedance between damp and acceptably dry concrete. The meter is simply placed on the clean surface of a concrete subfloor and a reading is presented on a small display. As easy as it is to use, the meter is as easily fooled. Differences in concrete density, aggregate size, location of reinforcing steel within the body of the slab, and surface contamination can all affect the ability of the meter to accurately assess concrete subfloor moisture. Moisture meters are best used as a quick comparative indicator and should not be used as the sole evaluation method to determine the acceptability of coating the concrete with a non-breathable coating.

The calcium chloride test is designed to measure the amount of moisture vapor emissions from the surface of a concrete slab in accordance with the procedure in ASTM F1869.

The calcium chloride test dynamically measures the amount of moisture vapor that is being emitted from the surface of the slab by placing a desiccant, a material with a high affinity for water, under a sealed dome. Results are reported as pounds of moisture per 1,000 ft2 of floor space (or kg per 100 m2) in any given 24 hours of time. Therefore, a test result of four pounds would mean that for every 24 hours of time, four pounds (or roughly about ½ gallon) of water is being emitted from every 1,000 square feet of slab surface area.

Both the handheld moisture meter and the calcium chlo-ride test share a serious limitation: neither is able to identify moisture more than about 13 to 19 mm (1/2 to 3/4 inch) below


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the concrete surface. Additionally, per the ASTM method-ology, the calcium chloride test cannot be used on lightweight concrete (Portland cement or gypsum).

The relative humidity test, ASTM F2170, is an in-situ relative humidity test that statically measures the relative humidity within the body of a slab by drilling a small hole into the slab and then inserting a temperature/relative humidity probe into the hole. The results are reported as air tempera-ture within the slab and the percentage of moisture contained within that air (relative humidity). As such, 22 degrees C (71 degrees F) and 99% relative humidity means that the air within the capillaries of the concrete slab is holding 99% of the mois-ture that it can possibly hold at that temperature. An increase in relative humidity within the slab indicates an increased amount of available moisture.

Similar to the ASTM F2170 humidity test, ASTM F2420 uses a humidity probe covered by an insulated hood to help control any surface effects on the humidity readings.

It is generally agreed that anything above three pounds of moisture vapor emissions, when tested using the calcium chlo-ride test method, represents an adverse moisture condition. There is less agreement about the relative humidity maximum. In either case, the floor coating or floor covering manufacturer’s literature should be consulted to determine which test to run and the maximum moisture limits allowed by that manufacturer for the selected flooring system.

The plastic sheet method (ASTM D4263) is a specified requisite by several manufacturers. The stated validity and necessity of passing this test is that it verifies that the available moisture vapor emissions to the as-prepared surface of the concrete will not result in liquid phase water at the surface for 16 hours. This is believed to assure that the applied polymer (primer) is allowed to penetrate and wet the concrete surface and achieve initial cross linking without the interference of liquid phase water which could inhibit penetration, wetting, and polymer cross linking.

NOTE: None of the tests described here addresses the source of moisture. Moisture may reside in the concrete slab as a result of excess water used during the concrete installa-tion; water may have entered the slab from surface exposure; or water vapor may originate from a source below the slab (or the slab edges) if a vapor barrier is not in place or is not functioning. See discussion in Section 4.2.

5.5.3 Moisture Mitigation: Moisture vapor emission should be controlled to match the resinous flooring system limitations in order to prevent subsequent bond problems with an installed impermeable coating or flooring system. If the project schedule should be expedited, moisture levels may be adequately reduced by various commercial surface treatments, which should be used in accordance with specifications or as approved by the surfacing manufacturer. Following rehabilita-tive treatments, the surface should be retested in accordance with the coating or floor covering manufacturers’ instructions.

5.6 Repair of Surface Imperfections: Dings, holes and surface imperfections (other than cracks) that are less than 13 mm (1/2 inch) in depth and 50 mm (2 inches) in diameter

should be filled with the same or compatible resin as the coating or surfacing, compounded into a mortar or gel, or fillers recommended by the surfacing manufacturer.

Holes, spalls and other surface imperfections that are greater than 13 mm (1/2 inch) in depth and 50 mm (2 inches) in diameter, where steel reinforcing IS NOT exposed, should be prepared so that the repair area is squared up and shoul-dered. Terminations of all repairs should be extended to a vertical abutment. Flash-patched edges, or edges terminated at a “skim coat” level on top of the concrete substrate, are not recommended. Sound out the area surrounding the spall or hole by tapping with a hammer or dragging a chain on the surrounding concrete in all directions extending from the repair area, listening for hollow sounds. The limits of hollow sounds around the perimeter of repair area indicate the limits of unsound concrete substrate.

Mark the repair area by chalking out a rectangle or square perimeter that includes the entire unsound area. Refer to “layout” as illustrated in ICRI No. 310.1R. The marked perimeter should be sawcut to a minimum depth of 16 mm (5/8 inch) or to a depth recommended by the repair product manufacturer. Edge shoulders should be perpendicular to the substrate surface, as illustrated in ICRI No. 310.2. The repair area, including edges, should be vacuum cleaned and free of oils and greases. The repair material to be used should be compatible with the surfacing manufacturer’s flooring system. Repair methods should comply with specifications and/or the manufacturer’s instructions.

Holes, spalls and other surface imperfections that are greater than 13 mm (1/2 inch) in depth and 50 mm (2 inches) in diameter, and where steel reinforcing IS exposed, should be repaired in accordance with ICRI Guideline No. 310.2. Any unsound, disbonded concrete above the reinforcing steel should be removed. The extent of the unsound, disbonded concrete may be determined by sounding methods described above and by evaluating the soundness of the concrete during removal.

All exposed corroded steel reinforcing bars should be undercut if exposed reinforcing steel is rusted or otherwise corroded. A minimum 19 mm (3/4-inch) clearance between exposed bars and surrounding concrete, or 6 mm (1/4 inch) larger than the largest aggregate, whichever is greater, should be maintained. Concrete removals should extend along the bars to locations where the bar is free of bond-inhibiting corrosion and is well bonded to the surrounding concrete. If corroded bars have lost significant cross-section, and this condition is not addressed in the specifications, a structural engineer should be consulted for further direction. The struc-tural engineer may recommend full bar replacement or the addition of a supplemental bar over the affected section.

If non-corroded reinforcing steel is exposed during the undercutting process, care should be taken not to damage the bar’s bond to the surrounding concrete. If the bond between the bar and the concrete is broken, undercutting of the bar should be required. Any reinforcement that is loose should be secured in place by tying to other secured bars or by other approved methods. All heavy corrosion and scale should be removed from the bar as necessary to promote maximum bond


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of replacement material, preferably by blasting with oil-free abrasive. Tightly bonded light rust buildup on the surface is not usually detrimental to the bond unless a protective coating is being applied to the bar surface. If a protective coating is to be used, surface preparation of the bar should comply with the manufacturer’s instructions.

Supplemental replacement bars used to correct eroded bars may be mechanically spliced to old bars, or supplemental bars may be placed parallel to and approximately 19 mm (3/4-inch) from existing bars. Lap lengths should be determined in accordance with ACI 318.

Contractors and manufacturers should exercise particular caution regarding repair or rehabilitation of reinforcing steel. Load design is outside the domain of those not licensed or qualified to fully analyze structural requirements.

The repair material selected should be compatible with the surfacing manufacturer’s flooring system and should be installed in strict accordance with specifications and repair material manufacturer’s requirements. Frequently, surface repairs are made with mortars of the same or similar resin bases as the floor surfacing. The concrete surfaces surrounding areas to which repair material will be applied should be sound and solid, free of dust, dirt, greases, and oils.

The repair area, including shoulders, should be vacuum-cleaned, free of dust, dirt, greases, oils, and any other contaminants that may inhibit bond. The edges of deficient areas that require planarity and sloping correction prior to application of surfacings should be keyed-in to terminate at square shoulders or edges without flash patching. After deter-mining the substrate area to be corrected, chalk-lines should be snapped to outline the perimeter. The substrate should be sawcut to a depth of 1/4 inch (6 mm) or twice the thickness of the surfacing material to be installed, whichever is greater. If surfacing material is less than 1/8 inch (3 mm) thick, the kerf (the width of the saw blade) should be at least 3 mm (1/8 inch) in width. If surfacing material is 3 mm (1/8 inch) or greater, another sawcut to a depth of 3 mm (1/8 inch) inside the perim-eter should be made. The distance between the outside and inside sawcuts should be:

• 76 mm (3 inches) for surfacing material thickness up to 5 mm (3/16 inch);

• 101 mm (4 inches) for surfacing material thickness up to 10 mm (3/8 inch);

• For surfacing thickness greater than 13 mm (5/8 inch), the distance between the two sawcuts should be an additional 25 mm (1 inch) for each 3 mm (1/8 inch) thickness over 13 mm (5/8 inch).

After the outside and inside sawcuts are made, the key is created by chipping out concrete between them, making a sloping transition that increases in depth from the inside to outside sawcuts. The profile within the substrate correction area should be created as described in ICRI Guideline No. 310.2, and as later described in this document. The repair material selected should be compatible with the surfacing manufacturer’s flooring system and should be installed in strict accordance with specifications and repair material manufac-turer’s requirements.

5.7 Surface Profile: Surfacings and coatings adhere to the concrete surface primarily through mechanical attachment during the curing process. In general, a profiled substrate surface will gain maximum adhesion by removing the “weak” concrete paste, removing surface contaminants, and increasing the profile for mechanical bond. Depending upon the resin system “wetting” capacity, some systems may require less surface profile than others.

There are several industry publications providing guid-ance on surface profile, how to achieve a desired profile, and recommendations for profiles by system type being installed, these include:

• ICRI Guideline 310.2• SSPC-SP 13/NACE No. 6Refer to ASTM D7682 for additional details on surface

preparation of concrete.Always refer to manufacturer's recommendations for

surface preparation and profile for each system.

6. Application of Thick-film Coatings and Surfacings

6.1 Pre-Application Procedures: The work area should be checked to ensure that environmental conditions for appli-cation are within specifications, the work area layout facilitates ease of application, traffic control procedures are in place, and adequate lighting is provided.

6.1.1 Facility and Environmental Conditions: Prior to daily start-up, facility and environmental conditions should comply with specification and coating or surfacing manufac-turer’s requirements. Leaks, including those from pipes and equipment that could interfere with coating or surfacing opera-tions, should be stopped, plugged or diverted away from the work. Doors, airflow vents, and other ingress/egress openings that could change or alter environmental conditions if opened or left open should be barricaded or show proper signage indicating the doors are to remain closed. Substrate and air temperatures should comply with specifications and manu-facturer’s requirements during application and cure of applied materials. Relative humidity and dew point requirements should comply with specifications and manufacturer’s instruc-tions during application. Most coatings require the substrate surface temperature to be at least 5°F (3°C) above the dew point temperature. Whenever possible, installations should be done after a building has reached its operating tempera-ture with the HVAC in operation for at least one week. The results of all environmental testing and results taken during the course of each workday should be recorded. Material temperatures should fall within the range of specifications and manufacturer’s requirements. Typical material temperatures should be recorded. For at least two weeks prior to application, environmental conditions should be representative of normal operating conditions at the facility in order to allow the concrete substrate to reach equilibrium.

6.1.2 Layout of the Work Area: The project area should be arranged to facilitate material movement and smooth


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application procedures. Each day’s work should be planned so that the work progresses efficiently from the furthest point to a point nearest a central exit area. The mixing area should be located close to each day’s work location to facilitate staging and mixing. The floor of the mixing area should be protected with impermeable and absorbent covering to prevent damage from and facilitate clean up of any spilled materials. Polyethylene overlaid with cardboard, with the edges taped, is a typically used protection method. A sufficient quantity of materials should be staged in the mixing area to complete each day’s work. Materials should be arranged by product and product type. Batch numbers of products used in each day’s work should be recorded. Mixers, mixing equipment and safety equipment required for mixing and application should be included in the staging. A cleaning station for cleaning of equip-ment and tools should be set up as well as disposal collection containers. Arrangements should be made for proper disposal of debris and spent containers.

6.1.3 Traffic Control: Surfaces in the vicinity of the project that are not intended to be surfaced or coated should be protected from misplacement of materials and products, as well as from the dirt, dust and debris generated from applica-tion operations. Signs and barricades should be employed to keep foot and vehicle traffic away from the floor during appli-cation and curing according to contract specifications or prior agreement with the governing authority. High-visibility warning ribbon, cones and other warning materials should be promi-nently displayed.

6.1.4 General Illumination and Lighting Requirements During Application of Floor Coatings or Surfacings: SSPC-Guide 12 provides overall and specific illumination recommendations appropriate for inclusion in specification development and use during preparation, application and inspection.

Work location classification should be determined to be Hazardous, Non-Hazardous or Wet, as described in SSPC-Guide 12. Lighting fixtures should comply with requirements for the appropriate work location classification.

A light meter that provides readings in foot-candles should be used to determine the amount of existing light. For general work area measurements, the meter should be placed on a horizontal plane parallel with the floor or surface, as described in SSPC-Guide 12. A minimum of 5 measurements that are representative of the work area should be made, keeping the sensor perpendicular to the surface. The measure-ments should be recorded and the average calculated. The measurement average should be compared to the criteria in SSPC-Guide 12, which shows minimum and recommended work area illumination requirements in foot-candles (10–20 for general work area; 20–50 for surface preparation and applica-tion; 50–200 for inspection), maximum luminance ratios, and includes recommendations for use and maintenance of lighting equipment and fixtures.

6.1.5 Masking and Protection: Surfaces adjoining or

adjacent to the area being finished that are not intended to

be coated or surfaced should be protected from trowel, power trowel, roller spatter, overspray and other misplacement of materials, as well as from dirt, dust or debris generated by the application operation. Walls should be masked at least 18 inches from the floor when installing a broadcast system that may result in resin being splashed during the broadcast process.

Drains, trench drains, pipe openings, or any other opening where errant or spent materials could enter should be blocked off and masked. Draping and masking materials should be secure and tightly fastened around equipment and other objects and areas that require protection. Flooring terminations adjoining other surfaces should be taped off in such a way that the finished termination is neat and straight after the masking is removed. Masking or protection materials that could bond to the surface during cure should be removed immediately after any coating or surfacing application, before the coating or surfacing sets. If necessary, these materials should be reap-plied after cure and before succeeding coating or surfacing operations. If protection of finished flooring is required, the coating or surfacing system should cure as described in requirements, prior to placing protection materials.

6.2 Preparation of Joints: Joints comprise an integral part of concrete structural design, providing planned, system-atic details to accommodate concrete placement. They allow for contraction during curing, expansion and contraction during temperature variations, differential settlement and crack control. It is important to be able to identify the functions of joints encountered in coatings and surfacings work and to treat each joint in a manner that retains its full functionality. ACI 116R defines five functional joints. Unless otherwise speci-fied, without other special treatments, coatings and surfacings should not be placed over moving joints. Movement in func-tional joints generally exceeds elongation at break properties of coatings and surfacings, resulting in cracking of finished work above or in proximity of the covered joint.

New concrete continues to shrink. As a rule of thumb stan-dard concrete will contract 3 mm (1/8 inch) over a 6-m (20-foot) span. This contraction will continue as the excess moisture evaporates from the slab over the course of more than a year. Joint fillers that are not designed to accommodate the antici-pated movement generally will exhibit an adhesive failure at the filler-concrete surface. There are concrete designs with low water-to-cement ratio and super plasticizers to facilitate placement that are low shrinkage concrete minimizing the expansion of the joint over time. In new concrete applications confirm that the concrete mix is compatible with the joint mate-rial and installation timing to avoid joint failure.

Existing joints should be prepared by removing existing fillers, sealants or other materials prior to coating or surfacing application. Following removal of joint materials, both sides of the joint should be sawcut to create clean, bondable surfaces. The surface should be vacuum cleaned after sawcutting. Benchmarks may be created by driving nails or other devices into the center of prepared joints, along straight runs, to allow for later sawcutting and sealing following completion of finished coatings and surfacings. If the contract specification or


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manufacturer’s recommendations require joints to be covered with coatings or surfacings without other special treatments, the appropriate sealant should be installed as described in the contract specification or the surfacing manufacturer’s instruc-tions. SSPC TU-2/NACE 6G197 offers substantial guidance on joint designs, and should be consulted in detail, especially for special joint treatments.

6.3 Repair of Cracks: Cracks should be pretreated prior to application of any coating or surfacing, unless otherwise directed by specification or surfacing manufacturer. Generally, surfacing thicknesses less than 5 mm (3/16 inch) will mirror substrate cracking, even if the cracking is non-moving.

• Non-structural, non-moving cracks should be routed open with a saw, grinder or concrete routing appa-ratus to a minimum depth of 12 mm (1/2 inch)

• Cracks less than 3 mm (1/8 inch) in width should be opened to at least 3 mm (1/8 inch).

• Cracks greater than 3 mm (1/8 inch) but less than 6 mm (1/4 inch) in width should be opened to at least 6 mm (1/4 inch) in width.

• Cracks 6 mm (1/4 inch) or greater should be cut on both sides of the crack, opening the crack wider than the existing width.

All cracks should be vacuum cleaned to remove dust, dirt and debris. To repair the concrete and return the substrate to a monolithic surface, prepared cracks should be filled with the same or similar resin as the coating or surfacing, compounded into a mortar, gel or crack filler as recommended by the surfacing manufacturer.

Structural cracking, especially that found in suspended concrete around structural members and large moving machinery, should be analyzed by qualified engineering professionals to determine the relationship of cracking to the overall construction integrity. Structural cracks may be moving or non-moving, with stabilization and treatment methods deter-mined by engineering professionals. Non-moving cracks are generally stabilized by several methods, including providing additional support and epoxy injection. If future movement of a crack cannot be ruled out it should be treated as a moving crack.

Moving cracks in stabilized concrete are generally treated as functional joints. The effects of movement are controlled by the use of flexible sealant systems, compression seals, and other treatments over which hard coatings and surfacings are usually not applied. Hard, inflexible coatings and surfacings will not absorb movement and will reflect substrate cracking, requiring functional joints or cracks acting as functional joints to be incorporated separately as part of the finished coating or surfacing system. Irregularly shaped moving cracks are usually straightened by completely filling the crack with an adhesive resin, usually epoxy, then making a straight sawcut between the two endpoints of the crack.

Topical treatments and filling of cracks by the use of flexible membrane systems helps to absorb or cushion move-ment and mitigate substrate crack reflection through an overlaid surfacing. Any topical membrane treatment should be used in strict accordance with specifications and surfacing

manufacturer’s instructions. Certain membrane systems may require placement of tape or wax bond breaker material over the crack. Usually a 25-mm (1-inch) wide bond breaker mate-rial is centered over the crack, and a 101 to 152-mm (4- to 6-inch) membrane, sometimes reinforced with fiberglass, is applied over the bond breaker. Other membrane systems may not require the use of bond breakers, but may require that the crack be pre-filled with a flexible product prior to application of the membrane.

Additional information on concrete cracking may be found in SSPC TU 2/NACE 6G197 and ACI 224-1.

6.4 Mixing: Most resins (unless mixed by an application unit) and aggregate blends should be mixed in accordance with specifications and the surfacing manufacturer’s requirements.

6.4.1 Mixing Station: A mixing station is a designated location near the installation work area that is used to orga-nize materials, to double-check quantities, and to mix resins. It should provide quick access to safety equipment, including safety data sheets and product data sheets, and may also serve as a central cleanup area. A suitable station should help to keep the jobsite organized and clean, and include:

• Places to organize all tools needed for efficient installation

• Drill motors, multiple mixing blades (jiffy type & propeller), rags, drop-cloths, extension cords, mixing containers, measuring containers, chip brushes, disposable gloves

• Aggregates, traction additives, thinning solvents, cleaning solvents for tools

• Places to clean all tools at finish of job• Safety tools, glasses, hard hats, rubber gloves and

respirators if needed• Products separated by component into rows or

columns (e.g., A-side & B-side)• Trash can

6.4.2 Mixing Process: Materials should be mixed in accordance with project specifications and the manufacturer’s requirements. Clarification should be obtained for any discrep-ancies identified between the project requirements and those of the surfacing manufacturer. Safety data sheets (SDS) regarding product use, including ventilation, dust control and protective personal equipment should be consulted in advance.

Resins may be pre-blended using a low speed drill (maximum 450 rpm), usually 1/2 - 3/4 hp, and mixing paddle, generally a 3-bladed paddle designed to pull the mixture through the mixing head. A heavy-duty drill and paddle may be suitable for small mixes. Larger mixes may require fixed-arm mechanical mixers specifically made for blending resinous mortars. These mixing vessels, which are sometimes referred to as “chain mixers” or “bucket mixers,” utilize standard 20-liter (5-gallon) pails and are also available in 40-liter (10 gallon) and 55-liter (15 gallon) sizes. Wheelbarrow-type and pedestal-type fixed-arm “epoxy mixers” are also available, holding about 20 liters (5 gallons) of mixed materials. Common electric plaster/mortar mixers or “paddle mixers” in various sizes ranging to


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approximately 0.4 cubic meters (15 cubic feet) are also avail-able and are suitable for mixing resinous mortars. Other mixing equipment is available, generally for specific applications, with built-in metering apparatus.

Hand stirring or stir sticks should not be used. Each component should be mixed separately until the ingredients are homogeneous and uniform in color. Where multiple-component materials are to be mixed, separate mixing paddles should be used for each individual component, so no component is contaminated with another until final mixing. The product manufacturer’s instructions regarding mix ratios should be followed.

Some manufacturers sell multicomponent products in kit form, requiring the full use of the components in each container. Other manufacturers require the components to be measured and mixed as described in specific ratios, for example, two parts of resin to one part hardener. Measuring vessels should produce consistent volumes from mix to mix. When emptying components from one vessel into another, all material should be scraped from the sides and bottoms of the containers to ensure that the mix ratios are not compromised. Unless other-wise specified, products with aggregates, powders, or other fillers that are to be field-added, should not be added to liquids until all liquids are thoroughly mixed and blended together for the duration specified by the manufacturer. Aggregate, powder, or other fillers should be added into the blended liquids using mechanical equipment that will produce a mixture with smooth, uniform consistency, free of lumps and entrapped air.

Manufacturers do not usually recommend thinning. If thinning is allowed by specification or manufacturer’s instruc-tions, only solvents or thinners specifically recommended by the manufacturer should be used. Solvent additions should not exceed the amount recommended by the manufacturer. The type and amount used per mix of each thinner or solvent should be recorded. Thinners and solvents should be blended into the liquids prior to addition of aggregates or other fillers. The addi-tion of thinners will affect the calculation of expected dry film thickness from wet film thickness measurements and may alter the performance characteristics of a particular coating.

The pot life and working time of specific resinous mate-rials should be taken into account when considering use of mixing equipment. Materials with short pot lives and working times should be batched in smaller mixes and mixers lest they start to cure before application.

Some resin-rich systems containing heavy aggregates, such as steel, garnet, granite, aluminum oxide and other fillers, tend to settle quickly. If the batch contents are not dispersed directly over the floor for immediate screeding, it may be necessary to remix the material prior to use.

Blended materials from previous batches should not be allowed to harden prior to mixing the next batch. Mixing equipment should be kept clean and free of hardened or cured materials and other contaminants. Solvents and thinners used for cleaning should not be used for any other purpose, and should be properly disposed of in accordance with applicable regulations. Up-ending buckets on floor to allow them to drain could contaminate the surface with unmixed resin from upper edges of the buckets.

6.5 Priming: Most manufacturers’ floor coating and surfacing systems require use of primers to enhance adhe-sion of the system to the prepared substrate and to minimize outgassing (the release of air from concrete as concrete temperature rises). Outgassing can create pinholes and blisters in floor coatings and surfacings. System primers are typically formulated to be applied at a range of 125 to 150 µm (5 to 6 wet mils) in order to wet out and seal the concrete substrate prior to application of the rest of the system. Most primers are low-viscosity for proper penetration into the concrete surface. Dry-film thickness (DFT) measurements for cured primer thickness should not be used, unless otherwise specified or instructed by the surfacings manufacturer. Wet film thickness (WFT) measurements taken immediately after application give more appropriate indications of coverage, especially if the primer is of very low-viscosity and penetrates a permeable concrete substrate.

The primer should be mixed as described in the manu-facturer’s requirements. It may be applied by squeegee, roller, spray or brush in a uniform thickness and at a coverage rate complying with project specifications and manufacturer’s instructions. Brushes or other application tools should be used to cut-in edges and around pipes, equipment, corners and other appurtenances to ensure complete substrate coverage. These areas should be cut-in to a distance sufficient to allow proper tie-in with subsequent application tools or equipment. Cut-ins should be done only as far ahead of the balance of the priming operation as is necessary to allow uniform curing of the entire priming application. The primer should not be allowed to “puddle,” or accumulate in low spots. If puddling occurs, the excess material should be brushed out or other-wise redistributed.

Spiked shoes are recommended for walking over the wet floor after the area is primed to minimize contamination and prevent damage to the wet primer. The recommended recoat time and sequence for application of the next coating or surfacing layer should be carefully followed. Some systems require immediate application of subsequent material into wet primer; others vary by time and temperature; and others require the primer to be cured. Job specifications and the manufacturer’s data sheet and application instructions should be consulted for specific directions. If succeeding applications require material to be applied into wet primer, priming should be limited to the area that can be covered with succeeding material while the primer is still wet. If the primer cures or sets prior to application of a succeeding coat, the specifications or manufacturer’s instructions for corrective action should be consulted. Usually those areas are required to be re-primed, but specific corrective action can vary by system.

If the succeeding application requires the primer to be cured, some manufacturers recommend that the primer be “seeded” with dry, clean aggregate, generally 35 mesh to 60 mesh in size, depending upon thickness of the flooring system.

6.5.1 Amine Blush: Following the recoat window of epoxy primers and other applied layers over which additional coat-ings or surfacings will be installed, the surfaces should be


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inspected for the presence of amine blush and other contami-nants that could prevent or inhibit adhesion and contribute to intercoat delamination.

Amine blush most frequently manifests itself as an oily, greasy, wax-like residue over the surface of an epoxy coating or surfacing. Specifically, an amine co-reactant in a coating or surfacing reacts with carbon dioxide and water to form an amine carbamate, which can, and usually does, adversely affect adhesion of subsequent coating or surfacing applica-tions. Recognition and removal of amine blush is critical for successful installations.

Manufacturers do not uniformly indicate on system data sheets or application instructions product susceptibility to amine blush or precautions to be taken if their specific prod-ucts are susceptible to amine blush. Product users—owners, specifiers, contractors and inspectors–should contact the manufacturer’s technical service department directly for clari-fication if precautions about amine blush are not published.

Conditions of high humidity or moisture or low or declining temperatures during cure, and especially the combination of high humidity or moisture and low or declining temperatures during cure, present high potential for blush formation.

In colder climates, isolated areas away from heat, espe-cially near exterior walls, may develop amine blush, while other areas may not. Close inspection of the entire area is recommended, paying particular heed to susceptible isolated areas. Air-conditioned areas may also present environments suitable for formation of amine blush.

Advanced stages of amine blush formation are easier to detect than less advanced formations. In its most advanced stage of formation, amine blush is evidenced by a milky-white opalescence on a surface, feeling very oily or greasy to a point where the surface is slippery. Initial appearance might indicate to the observer that the coating or surfacing did not cure. Less advanced formation stages may not exhibit a milky-white opal-escence, but may present only a slight oily or greasy residue, difficult to feel. This stage of formation is the one that creates the most difficult problem, as subjective discovery or recogni-tion of the phenomenon may be overlooked or missed.

Amine blush can be removed by detergent washing. Solvent washing is not recommended as residues may leave chloride salts and other bond-inhibiting contaminants on the surface. Blush is best removed by use of a floor scrubber utilizing detergent and warm water, followed by thoroughly rinsing the scrubbed surface. Allow treated surface to dry completely, and then re-inspect the surface. Rewash, rinse and allow drying if blush is detected. Then re-inspect. Usually amine blushing is easily removed with a single wash and rinse. Sanding the surface after removal of the amine blush provides additional insurance of a good bond to the subsequent coat.

6.5.2 Inspection for Other Contaminants: Depending on the facility or operation, ongoing processes may generate dirt, dust, or oily mists that can collect on surfaces after cure. After the applicators leave the area, people may walk over cured or uncured surfaces, tracking contaminants onto the surface. The cured surface should be inspected for other contaminants

that may have formed during or following cure. Removal of any contaminants prior to subsequent surfacing application is necessary for proper adhesion.

6.6 Recoat Window (Time): The recommended recoat time for application of the next coating or surfacing layer should be strictly observed. Some systems require immediate applica-tion of the next material to be installed directly over wet primer. Others vary by time and temperature, and still others require the primer to be cured. Specifications and manufacturer’s data sheets and application instructions should be consulted for specific direction.

6.7 Application of Surfacing

6.7.1 Coved Base Preparation: Integral coved base is that part of the finished flooring system which terminates at floor edges by turning up abutments, such as walls, equipment pads and other vertical surfaces, usually from 102 to 203 mm (4 to 8 inches) in height. It can vary from a simple 25-mm (1-inch) spoon-cove to a wainscot application covering the lower part or all of a wall. Vertical substrates to which coved base may be applied may be constructed of concrete, cement masonry units, glazed masonry units, brick, wood or drywall. Care should be exercised to ensure that the structure of a vertical substrate is sound, solid, and stable. The surface condition of a vertical substrate, especially drywall or wood, should be inspected for soundness and compatibility with the materials to be applied. Deteriorated drywall or wood substrate sections may require removal and replacement with more compatible substrate materials such as cement board. Base design should be clear and understood to determine extent of proper preparation and termination techniques. Some factors that determine prepara-tion methods include, but are not necessarily limited to:

• Height of the base• Existence of joints at or near wall-floor intersection• Use of metal or plastic termination strip at top of base• Use of reglet (sawcut) as top termination• Use of bullnose (rounded) top termination• Use of feathered top termination• Use of spoon-cove (radius) only• Use of splay or chamfered baseUnless otherwise specified, the top of the coved base

should be parallel to the elevation of the finished floor, espe-cially where the floors are pitched or sloped, or the finished system may have an irregular appearance.

If the base is to be applied to finished wall surfaces, careful masking and protection will be required during prepa-ration operations to minimize damage and staining. The use of duct tape or other strongly adhesive tape may remove finished wall surfaces. Using masking tapes designed for removal with minimum surface pull-off can reduce damage. The planarity of the base substrate should be repaired and patched with appropriate resinous or polymer-cementitious materials as specified or as described in surfacing manufacturer’s instructions. Surfacings other than troweled mortar systems may require the coved base to be formed from resinous or


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polymer-cementitious mortar applied by trowel and then coated, tying-in the specified system at the termination of the cove or splay. When this method is used, metal or plastic termi-nation strips placed at the toe of the cove often result in better base-floor transitions. The top of the base should be finished in straight, neat lines.

Joints at wall-floor intersections may require the use of sealant to form the cove or splay to prevent cracking. Depending upon anticipated movement, other methods may be used, such as forming the cove with sealant, applying a bond breaker over the sealant, then applying resin-impreg-nated fiberglass from the top of the base to approximately 102 to 203 mm (1 to 2 inches) beyond the cove onto the floor.

6.7.1.1 Coved Base Installation: Integral coved base turned-up vertical abutments, such as walls and equipment pads offer unique sanitation and cleanability features in resinous floor coating and surfacing systems. In the flooring systems described below (with the exception of troweled mortar flooring systems), coved base is formed separately from the surfacing system. In most flooring systems, formed bases are generally coated or surfaced with the same neat resins as the flooring matrix, but without aggregates. The coved base should be installed according to contract specifications and manufacturer’s recommendations. Its substrate should be sound, stable and prepared. If the specified flooring system is other than troweled mortar flooring, the coved base, spoon cove or splay is formed with resinous or polymer-cementitious mortar. The coved base should be overcoated using the same resins as the floor coating or surfacing material, as described in the contract specification and the surfacing manufacturer’s instructions. The finished base should be neat, straight and without surface irregularities. SSPC-TR 5/NACE 02203/ICRI 710.1 provides drawings illustrating various types of coved base installations.

6.7.1.2 Precast Cove Base: Polymer precast floor-to-wall cove systems have been used for commercial, retail, institutional, residential and industrial applications. The cove is bonded to the wall and floor surfaces, and overlaid with selected floor polymer or cementitious products. The correct shape and height around the perimeter of the room should be formed to meet the Environmental Heath Department's sanitary requirements. When this cove base and floor area is coated, it provides a uniform, smooth, seamless, and integral floor-to-wall juncture that produces a sanitary and easily main-tained floor.

6.7.2 Thick-film Floor Coating Systems: Thick-film floor coating systems applied by methods other than spray applica-tion are generally 100% solids systems, such as epoxies, or low VOC systems, such as urethanes, incorporating chemi-cally cured resins with inert fillers applied in single or multiple layers. They produce a cured thickness greater than 500 µm (20 mils), but usually not more than 1,500 µm (60 mils). Thick-film flooring systems, applications and procedures vary by manufacturer and system. Specific application requirements should be carried out as described in the contract specification

and the surfacing manufacturer’s instructions. Substrate surface irregularities should be patched, repaired and other-wise rehabilitated prior to application. The entire substrate surface should be in plane, and all dings, holes, spalls and other surface imperfections should be filled with smooth repair transitions. If required, the substrate should be primed as described in the contract specification and the surfacing manu-facturer’s instructions. Instructions on recoat times should be strictly followed. If an epoxy primer is used and allowed to cure, the primer should be inspected for amine blush prior to appli-cation of any succeeding coatings or surfacings. Succeeding coatings should be applied uniformly, ensuring that the coating is applied within required wet film thickness (WFT) ranges to reach specified dry film thicknesses (DFT). Wet edges should be maintained by working new batches into wet edges of previ-ously applied material to eliminate “cold joints.”

The exact delivery thickness of specific resins should be determined by field-testing. The squeegee blade should be kept perpendicular to the floor surface or the delivery thickness will be reduced or inconsistent. Squeegee blades should be kept clean and free of resin build-up. As squeegees wear down from use, materials will be applied in thinner yields. If wet film measurements show insufficient thickness, squeegees should be inspected for wear. Worn blades should be replaced.

Depending upon its working time, the applied material should be allowed to settle out, then deaerated. Ensure deaer-ation techniques are completed before the applied material begins to take initial set. Applied coatings may be deaerated by use of porcupine or needled rollers manufactured for this purpose. Porcupine rollers should be used in a perpendicular direction to that in which the coating was initially applied.

Epoxy primers should be inspected for the presence of amine blush before application of subsequent or finish coats. To ensure full coverage and leveling, finish coats should be rolled in two operations, with the second rolling at right angles to the first. Any masking materials should be removed prior to cure.

6.7.3 Self-leveling Flooring Systems: Self-leveling flooring systems are generally 100% solids or low VOC systems incorporating chemically cured resins with inert fillers and powders applied in single layers that have a cured thick-ness greater than 750 µm (30 mils) (but usually not more than 3 mm [1/8 inch]). Self-leveling flooring system applications and procedures vary with the surfacing manufacturer. Specific application requirements should be carried out according to contract specification and the surfacing manufacturer’s instruc-tions. Substrate surface irregularities should be patched, repaired, and otherwise rehabilitated prior to application. The entire substrate surface should be in plane, with all dings, holes, spalls and other surface imperfections filled with smooth repair transitions.

Surface imperfections tend to reflect through finished thin- film coatings, requiring greater attention to finished substrate surface detail than do thicker surfacing applications. If metal or plastic strips are to be utilized, they should be installed according to contract specifications and manufacturer’s instructions.


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If required, the substrate should be primed as described in the contract specification and the surfacing manufacturer’s instructions. If an epoxy primer is used and allowed to cure, the primer should be inspected for amine blush. Instructions on recoat times should be strictly followed. The self-leveling mate-rial should be applied according to contract specification and the manufacturer’s instructions. Succeeding coatings should be applied uniformly, ensuring that the coating is applied within the wet film thickness range required to achieve the specified dry film thickness. Wet edges should be maintained by working new batches into wet edges of previously applied material to eliminate “cold joints.”

6.7.4 Slurry Flooring Systems: Slurry flooring systems are generally 100% solids or low VOC chemically cured resins, incorporating use of inert fillers and powders. Specific application requirements should be carried out as described in the contract specification and the surfacing manufacturer’s instructions. Slurry flooring systems are generally resin-rich systems filled with aggregates larger than self-leveling systems, troweled or squeegeed to the thickness of the largest aggregates. While resin-rich, these systems do not tend to flow out as readily after application as do self-leveling flooring systems. Slurry systems are generally applied in thicknesses from 1,500 µm (60 mils) to 3 mm (1/8 inch). If an epoxy primer is used and allowed to cure, the primer should be inspected for amine blush prior to application of any succeeding coatings or surfacings.

Slurry material should be applied as described in the contract specification and the surfacing manufacturer’s instructions. The mixed material should be poured in ribbons in application areas and should be applied to the specified thickness, maintaining wet-edges. Slurry material is generally applied to the thickness of the largest aggregate by “scrape-troweling,” but it may be applied to a specific thickness by gauge rake, pin screed, or notched trowel. Wet-film thickness measurements should be taken with sufficient regularity to confirm that the specified thickness is uniform. The applied material should be allowed to settle out, then deaerated. Subsequent finish coats should be applied as described previously.

6.7.5 Broadcast Flooring Systems: Broadcast flooring systems can be installed by applying unfilled or filled resinous receiving coats by roller, spray, squeegee or trowel, then broad-casting selected aggregates into the receiving matrix while the matrix is still wet and uncured. Broadcast systems generally range in thickness from 500 µm to 6 mm (20 mils to 1/4 inch). If an epoxy primer is used and allowed to cure, the primer should be inspected for amine blush prior to application of any succeeding coatings or surfacings. The receiving coat may be neat resins or resinous slurry materials. It should be applied as described in the contract specification and the surfacing manu-facturer’s instructions. After the receiving coat has settled out but is still wet, the selected aggregate should be broadcast into the wet matrix, preferably by means of commercially available aggregate blowers. The aggregate should be broadcast in a “raining” fashion so that it falls as perpendicularly as possible

into the wet matrix. If the aggregate is thrown directly at the wet matrix, it may cause “blowouts” or separation of the resin from the aggregate particles. The application of the receiving matrix and the broadcasting of the aggregate should be performed in nearly simultaneous operations to ensure the broadcast aggregate is properly received and has time to settle and wet out. The aggregate should be broadcast to saturation within a few inches of the edge of the applied receiving coating to allow for proper tie-in of subsequent receiving coats.

Uniform dispersal of the aggregate should continue until no wet spots show. As the aggregate continues to settle and wet out, wet areas may appear. Additional aggregate should be broadcast into these areas until they appear dry. After cure of the broadcast matrix, loose aggregate should be removed by sweeping and vacuuming. If the system or specification requires additional layers of broadcast filled matrix, the opera-tion should be repeated. If the system or specification requires grout coats or finish coats, ensure that materials applied subsequent to the first grout coat are inspected for amine blush. Generally, broadcast matrices without grout coats and/or topcoats are very rough and difficult to clean. The finished texture is determined by the size of the aggregate used or the thickness of subsequently applied coatings.

6.7.6 Troweled Mortar Flooring Systems: Mortar flooring systems are generally less resin-rich than other flooring systems, and are filled with larger proportions of blended aggregates. Mortar systems are generally applied by using trowels, gauge rakes or various types of screed-boxes to disperse the material to a selected thickness. The mortar system is then compacted to its specified thickness with trowels, power trowels, or other compaction equipment. Mortar flooring systems are generally applied in thicknesses of 5 to 13 mm (3/16 to 1/2 inch).

Troweled mortar systems are best applied in low general lighting conditions with the task lighting directed across the floor surface from a low angle, casting shadows where applied mortar is out of plane. Low general lighting conditions allow reduced task lighting requirements and greater worker comfort levels when task-light luminance ratio is a maximum of 5:1, as indicated in SSPC-Guide 12, Table 2. Trowel ridges and other irregularities in the applied mortar can be more readily and immediately detected and corrected by the flooring mechanic during application by use of contrasting lighting.

Substrate surface irregularities should be patched, repaired and otherwise rehabilitated prior to application, ensuring that the entire substrate surface is in plane and other-wise prepared to allow smooth transitions. Metal or plastic strips should be installed according to contract specifications and manufacturer’s instructions. If required, the substrate should be primed in accordance with the contract specification and the surfacing manufacturer’s instructions. Recommended recoat times should be followed. If an epoxy primer is used and allowed to cure, the primer should be inspected for amine blush prior to application of any succeeding coatings or surfacings.

Mixed mortar should be spread with trowels, gauge rakes, screed boxes or other devices to an initial thickness


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sufficient to achieve specified cured thickness after subse-quent compacting. Wet edges should be maintained. New mortar should be compacted to within a few inches of the edge of previously applied mortar to allow proper tie-in of subsequent compaction. Prior to mortar set, compacted areas should be inspected for irregularities or imperfections that can be corrected or removed, and necessary repairs should be made prior to cure. If work is stopped for breaks, lunches or at day’s end, the contractor should terminate the application at natural stop points, such as joints or termination strips, to minimize the appearance of cold joints. Terminations should be neat and straight. If integral coved base is part of the project requirements, a work crew of sufficient size should be avail-able to install the coved base just ahead of the mortar flooring application to permit proper tie-in and elimination of cold joints. If specified or allowed by owner’s representative, plastic or metal termination strips may be set on the floor to allow appli-cation of the coved base prior to the installation of the floor. Some mortar matrices, especially those with volumetric aggre-gate to resin ratios of greater than 4:1, exhibit some degree of porosity when viewed under magnification, and may require grout and/or finish coats to fill matrix and surface porosity. The surface should be inspected for amine blush prior to applica-tion of grout coats or finish coats. The finished surface texture is determined by the size of the broadcast aggregate used and/or thickness of subsequently applied coatings.

6.7.7 Fabric and Mat Reinforcement: Fabrics and mats, generally referred to as fiberglass, are usually supplied in rolls in varying widths. They may be incorporated as embedments in specific resinous systems to increase strength, durability, impermeability to chemical or solvent attack, resistance to high temperatures or thermal shock, and crack resistance. This reinforcement may also serve to reduce curing shrinkage of some resins. Certain fabrics and mats may be used in membrane systems and in systems designed for high chemical resistance and heavy mechanical exposure. Fabrics can be knitted, woven, nonwoven, directional or non-directional, and are manufactured in many different types, strengths, weights, weaves, elasticities and generic makeups. Mats are made by bonding glass fiber strands together with adhesive binders. Reinforcing fabrics and mats are available with a wide variety of different characteristics. Manufacturers design flooring systems to meet specific performance standards, integrating specific fabric and resin properties.

Unless otherwise specified, fabric or mat reinforcement should not be used in any coating or surfacing system unless its manufacturer has published system data sheets and appli-cation procedures describing the system and the specific fabric to be used. Systems may employ the use of a single layer of mat or fabric or multiple layers of different combinations. The general procedures for most fiberglass applications are similar, but each particular system should be applied according to contract specifications and the manufacturer’s instructions. Areas to be surfaced are generally laid out to minimize cuts and material handling. Pre-cut glass should be sufficiently oversized to allow ease of placement and handling. Glass should be loosely folded into 1- to 2-m (3- to 6-ft) sections. To

ensure pre-cut glass is kept clean and dry, it should be stored near the immediate work area.

The specified base coat, which may be unfilled or filled with aggregates, powders or other proprietary fillers, should be applied to the specified thickness over specified coated or uncoated substrate. Next, the first fold of glass should be unfolded and laid on the wet base coat, pressing the placed glass into the matrix with a trowel or roller. To minimize crimping and wrinkling, troweling or rolling should proceed from the middle of the glass toward its edges. Continue unfolding the rest of the length and working glass into place. To deaerate the composite, the applied reinforcement should be saturated with the specified clear resin, and then rolled out with a serrated or ribbed roller specifically intended for this operation. The reinforcement should be rolled vigorously until it loses its color and becomes translucent, indicating that it is thoroughly wet-out. However, the saturant coat should not be allowed to puddle. The saturated reinforcement may be lightly seeded by broadcasting clean, dry aggregate in a size and type specified or approved by the manufacturer. Protrusions and wrinkles should be ground off following cure. Any areas of glass that are dry and not fully saturated should be cut out, and voids and repaired areas should be filled with the specified resin or mortar before installation of remainder of the system. If additional layers of glass reinforcement are required, they should be applied as outlined in this section or as specified or required by manufacturer’s instructions.

6.7.8 Spray-Applied Flooring Systems: Some thick-film flooring systems may be spray-applied. Some parts of other flooring systems, such as primers or finish coats, may be spray applied. Certain flooring systems, such as polyurea systems, are generally spray-applied. Spray-applied systems can be sprayed from 250 µm to 6 mm (20 mils to 1/4 inch) and greater.

Plural component equipment is often used with fast-curing materials. Correct and consistent proportioning is critical for applied systems to cure correctly and to meet published performance data. Some resin systems require specific spray equipment for proper application, and the manufacturer’s recommendations should be followed for best results.

Most plural component equipment functions best with preheated materials, in-line heaters and heated lines, which reduce material viscosity. Some materials, such as polyureas, may require preheating to specific temperature ranges prior to spraying. Thermostatically controlled band heaters placed around the bottom, midsection and top of drums are gener-ally used for this purpose. The material should be agitated for uniform heating and to eliminate “hot spots.” Be aware that heating may take several hours depending upon temperature, age of material and pigment load.

In some applications transfer pumps are used to assist the high-volume movement of material from material containers to the lines and finally to the gun where the material is mixed and sprayed. To allow continuous material flow, especially when fibers or flakes are utilized, appropriate in-line filters should be used. When pumping material from drums, drum mixers should be used as described in the surfacing manufacturer’s requirements.


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If required, the substrate should be primed as described in the contract specification and the surfacing manufacturer’s instructions. Recommended recoat times should be followed. If epoxy primer is used and allowed to cure, the primed surface should be examined for amine blush prior to application of succeeding coat.

The gun should be held perpendicular to the surface at a distance that will ensure that a wet layer of coating is depos-ited uniformly. Deviation from this procedure generally results in uneven film build. Brush out or otherwise remove sags and runs from vertical surfaces.

Airless spray equipment is often used in application of thick-film coatings. The equipment manufacturer’s safety instructions should be consulted prior to use. The equipment should be sufficiently sized to properly spray high-viscosity materials as described in the surfacing manufacturer’s require-ments, using thinners only as recommended by the surfacing manufacturer.

Spray application should follow the contract specifications and the surfacing manufacturer’s requirements. Substrate surface irregularities should be patched, repaired and other-wise rehabilitated prior to application. The entire substrate surface should be in plane, and all dings, holes, spalls and other surface imperfections should be filled with smooth repair transitions. Surface imperfections tend to reflect through finished thin film coatings, requiring greater attention to finished substrate surface detail than do thicker surfacing applications. If required, the substrate should be primed as described in the contract specification and the surfacing manufacturer’s instruc-tions. Instructions on recoat times should be strictly followed. Masking and protection are important in spray application. Atomized overspray travels further than roller or trowel spatter that may require additional protective coverings.

Prior to their application, material components should be pre-mixed and then adequately blended according to the surfacing manufacturer’s instructions. Most flooring materials are 100% solids and are designed for installation without use of thinners or solvents. All materials should be applied according to contract specifications and the surfacing manufacturer’s instructions.

Coating should be spray-applied in uniform layers, with the edges of the spray pattern overlapping sufficiently to ensure complete coverage. Fast-cure systems, such as polyurea, are best applied using a crosshatch technique to minimize lap marks. Positioning the gun at different distances from the surface in systems with fast gel times can create different finish textures. Depending on the gel time of the material and the distance from the surface, textures can range from an orange peel to a heavy stipple. This texture will help to add to slip resistance and create a more uniform finished appearance.

Certain spray-applied materials, especially those applied by heated plural component equipment, may cure too quickly for conventional thickness testing. Nondestructive, ultrasonic dry film thickness gauges are commercially available and can be used to determine cured thicknesses over concrete substrates, provided that the coatings and surfacings are not aggregate-filled. Destructive testing, such as by Tooke gauge or cutting cured coating and measuring with a micrometer,

are other methods of measuring fast-curing film thickness. Destructive testing should only be used when specified, and the test area should be repaired according to contract specifi-cations and the surfacing manufacturer’s requirements.

The surfacing manufacturer’s re-coat and tie-in proce-dures should be strictly followed. Subsequent coats or layers of material should be applied in accordance with contract specifications and the surfacing manufacturer’s instructions. Some fast-cure systems require scarification, abrasion and/or softening existing coating with special solvent prior to the next application.

If the coating or surfacing is hard and not elastomeric, joints should be treated as described previously. If the spray-applied coating is flexible or elastomeric, joints and cracks should be treated based upon the manufacturer’s recommendations.

6.7.8.1 Safety Considerations for Spray Applications: Safety procedures are important in all aspects of flooring applications, however, safety requirements in spray applica-tions may be more complex than those required in traditional flooring application methods. While this document does not address specific safety procedures, those requirements and procedures pertaining to spray application should be investi-gated and followed. Some considerations include, but are not limited to:

• Hazards of spraying in closed spaces• Equipment grounding• Safety controls to prevent hypodermic injection of

coating into persons from gun tips and leaks from high-pressure fittings, connections and hoses

• Integrity of high-pressure air line fittings, connections and hoses

All equipment should be suitable for its intended purpose, capable of properly atomizing the coating to be applied, and equipped with appropriate and properly functioning pressure regulators and gauges. The equipment should be maintained in proper working condition. Spray equipment should meet the material transfer requirements of the local air pollution or air quality management district. Spray equipment should be kept sufficiently clean so that dirt, cured coating, and other foreign materials are not deposited in the coating film. Any solvents left in the equipment should be removed before using. Compressed air, if used, should be tested in accordance with ASTM D4285, and should be clean and dry. Electrical power, including proper voltage, amperage and grounding require-ments should be met.

6.7.9 Membranes and Membrane Flooring Systems: Membranes and membrane flooring systems are used either as an underlayment component of a harder coating or surfacing applied over it, or as a stand-alone system. Membranes and membrane flooring systems can be unreinforced or reinforced with fiberglass or textiles. Membranes and membrane flooring systems are generally applied at thicknesses from 500 µm to 6 mm (20 mils to 1/4 inch) or sometimes greater.

Substrate surface irregularities should be patched, repaired and otherwise rehabilitated prior to application. The entire substrate surface should be in plane, and all dings,


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holes, spalls and other surface imperfections should be filled with smooth repair transitions. If required, the substrate should be primed as described in the contract specification and the surfacing manufacturer’s instructions. Instructions on recoat times should be strictly followed. If an epoxy primer is used and allowed to cure, the primer should be inspected for amine blush prior to application of any succeeding coatings or surfac-ings. If metal or plastic strips are to be used, they should be installed according to contract specifications and manufac-turer’s instructions.

If the membrane is used as a crack dampener over cracks, it may be installed with or without fiberglass rein-forcing, according to contract specification or manufacturer’s instructions. The membrane should be applied to the required thickness, and centered over the crack at least 76 mm (3 inches) from either side. Some systems require cracks to be caulked with sealant prior to membrane application. In these cases, they should be sealed with the recommended sealant and allowed to cure prior to membrane application. If reinforce-ment is used, it should be embedded into a wet matrix and saturated with additional membrane. In projects where the entire floor is to be surfaced with a membrane, cracks and joints should be treated according to contract specifications and manufacturer’s instructions. Some systems may require joints and cracks to be pre-sealed. Other systems may require additional stripe coats or “stretch coats” to be applied over cracks and joints without pre-sealing. The base coat should be applied by squeegee, notched squeegee, pin-screed, notched trowel, roller, brush or spray to achieve specified thickness. If subsequent coats are required, the surface should be inspected for amine blush before application of any subsequent coating.

6.8 Providing Slip Resistance: Adding specifically sized or graded aggregates such as aluminum oxide, garnet, steel, silica, or polypropylene beads to the final finish can promote slip-resistance. The aggregate type and size are generally determined by anticipated traffic, chemical exposure and cleanability requirements. The use and size of any specific aggregate should be determined in accordance with the speci-fication and manufacturer's requirements. Aluminum oxide and garnet are harder than silica and are generally tolerant of most chemical exposures. Silica is the most readily available and least expensive medium used for slip resistance. Steel aggregate is most often used where its malleable qualities afford good resistance to impact. Polypropylene beads are most often used where cleanability and sanitation are high priorities. Combinations of these media can also be used. Broadcasting media into the applied material generally results in uneven dispersion, creating slippery areas and aesthetically displeasing finishes. Uniform slip-resistance is best achieved by adding the media to the mixed resins, then rolling out the material. Maintaining a ratio of a specific amount of added media to a specific amount of mixed resin will contribute to the desired uniformity. Both specifier and applicator may supply samples of various finished textures, but selection of the final texture should include input from users of the facility.

6.9 Treatment of Joints after Application: Unless other-wise specified, joints should be sawcut through the finished coating. Existing joints should be sawcut to their original width and depth. Benchmarks should be removed. Chalk lines should be snapped over the centers of joints. After sawing, the joint should be vacuumed to ensure it and adjacent areas are dry, clean and free of all dirt, dust, debris and other contaminants. New joints should be sawcut according to contract specifica-tions in neat, straight lines.

7. Post-Application Procedures

7.1 Cleanup: After application, the project area should be cleaned to a “broom-clean” condition, or to the condition required by the contract specification. All masking and protec-tion should be removed, especially from drains, equipment and entries. Drains that have collected dirt and debris should be vacuumed and cleaned. Cured resinous materials that may have adhered to the inside or outside of drain should be removed. Tape adhesives remaining on surfaces after masking and protection are removed should be cleaned off. All spatter and errant materials, cured and uncured, should be removed from surfaces not intended to receive coatings and surfacings. All trash and construction debris should be properly disposed off-site or in designated disposal areas.

7.2 Touchup: Any coating or surfacing irregularities discovered after masking and protection have been removed should be touched up according to repair procedures approved by the owner’s representative

7.3 Equipment: All equipment, tools and unused materials should be removed from the site. The owner’s representative should be provided with written environmental and physical requirements to ensure that the installed flooring system reaches final cure without damage. Written requirements should include:

• •Duration of time to restrict foot traffic and wheeled traffic from floor

• •Duration of time to restrict chemicals from engaging floor surface

• •Duration of time to maintain required minimum and maximum temperatures

• •Duration of time to maintain minimum and maximum relative humidity

• Other requirements

7.4 Protections: If required by contract specification or agreement, the floor should be protected as specified or with an appropriate protection material, such as plywood or composite board with taped joints, laid over polyethylene sheets.

8. Inspection

8.1 In-Process Inspections: Qualified, full-time inspec-tion by the owner’s inspector or a third-party inspector should be performed from job-start to job-completion, especially during


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preparation and application operations, to provide a system-atic, efficient quality control procedure by which to assist the owner and contractor in meeting specified and manufacturer’s requirements. Inspections and stop points are best established prior to beginning the installation. Positive results gained by qualified, full-time inspection cannot be overemphasized, and is deserving of greater detail beyond the scope of this docu-ment. For the purposes of this document, inspection should be continuous, ensuring prerequisite requirements of opera-tions are carried out completely, tested and results recorded according to specifications, manufacturer’s requirements and as suggested by this technology update.

Suggested inspection, testing and documentation areas prior to application:

• Environmental conditions • Surface temperature• Surface preparation and concrete condition as

detailed above• Concrete flatness• Crack repair, joint treatment, key-in and other details• Moisture vapor emissions if using a non-breathable

surfacing system• Material supplied to the site (source, volume and ratio

as specified)• Material color

Suggested inspection, testing and documentation stop points during the application:

• Primer volume application to manufacturers recom-mendation (Note: Cannot measure by mil gauge.)

• Primer contamination or amine blush• Cove base quality• Intercoat application windows• Application thickness of each step• Surface texture prior to final topcoat (when applicable)

Suggested inspection, testing and documentation after the application:

• System thickness to specifications• Adhesion to concrete (destructive test or sounding)• Gloss• Color uniformity• Waterproofing if specified• Texture and slip resistance• Straightness and neatness of termination lines• Planarity of floor• Depressions or humps in sloping runs which could

affect liquid flow• Smooth transitions at floor and trench drains• Smooth finishes at cove radii, internal and external

corners• Smooth transitions at in-floor terminations• Smooth transitions at intersections of adjacent floor

surfaces• Full application and finished edges of sealants• Spatter of cured and uncured resinous materials on

surfaces not being coated

8.2 Final Inspection: After final cleanup and any prelimi-nary deficiency remediation, re-inspect affected areas. Place in service based upon manufacturer's partial and full-cure requirements.

9. Maintenance

The flooring system manufacturer’s recommended cleaning and maintenance procedures should be followed and may depend on the flooring system installed and the service environment. In general the removal of dirt, debris and liquids is best accomplished using a vacuum method rather than a broom or mop method. The flooring system surface texture and service conditions will often determine the frequency of cleaning and the cleaning methods used.

In areas requiring a high degree of cleanliness, such as pharmaceutical manufacturing or food and beverage prepara-tion, chemical and high-temperature washing may be required. These considerations should be addressed when designing the flooring system to ensure compatibility and reliability. Chemical attack or mechanical damage should be repaired as soon as possible to maintain a safe work environment and maintain the integrity of the flooring system. Refer to the system manufac-turer for the appropriate repair materials and procedures.

10. Disclaimer

10.1 This guide is an SSPC consensus document devel-oped by SSPC: The Society for Protective Coatings. This guide is for information purposes only. It is not a standard. While every precaution is taken to ensure that all information furnished in SSPC guides is as accurate, complete, and useful as possible, SSPC cannot assume responsibility nor incur any obligation resulting from the use of any materials, coatings, or methods specified herein, or of the guide itself.

10.2 This guide does not attempt to address problems concerning safety associated with its use. The user of this guide, as well as the user of all products or practices described herein, is responsible for instituting appropriate health and safety practices and for ensuring compliance with all govern-mental regulations.

11. References

Drisko, Richard W. and Thomas A. Jones, eds. The Inspec-tion of Coatings and Linings, 2nd edition. Pittsburgh, PA, 2003: SSPC: The Society for Protective Coatings.

Farney, James A. and Steven H. Kosmatka. Diagnosis and Control of Alkali-Aggregate Reaction in Concrete. Skokie, IL: Portland Cement Association, 1997.

ICRI Concrete Repair Terminology. Rosemont, IL: International Concrete Repair Institute, 2010.

Nixon, Randy and Richard W. Drisko, eds. The Fundamentals of Cleaning and Coating Concrete. Pittsburgh, PA: SSPC: The Society for Protective Coatings, 2001.


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Thomas, M.D.A., B. Fournier, K.J. Folliard, and Y.A. Resendez. "Alkali-Silica Reactivity Field Identification Handbook," Federal Highway Administration (FHWA) Report No. FHWA-HIF-12-022, December 2011. <http://www.fhwa.dot.gov/pavement/concrete /asr/pubs/hif12022.pdf.> November 6, 2013.

Tuchscherer, Melissa, “Amine Blush Testing: Elusive Mystery or Good Old-Fashion Organic Chemistry?” PCI Magazine, May 1, 2012. <http://www.pcimag.com/articles/96380-amine-blush-testing--elusive-mystery-or-good-old-fashioned-organic-chemistry-> November 7, 2013.

Appendix A: Equipment

Specialty Application Equipment (from Fundamentals of Coating Concrete)

Notched Squeegees: Notched squeegees are used in the application of thick-film and self-leveling or other resin-rich mortar floor coating systems. Notched squeegees are gener-ally 0.6 to 1 meter [m] (2 to 3 ft.) wide, and are connected to 2-m (6-ft) handles in the rubber blade. The depth of the notches controls the thickness of the applied surfacing. Squee-gees are available with notches of various depths and offer a method of applying coatings in consistent thicknesses, from 250 to 750 µm (10 to 30 mils). Depending upon the viscosity of mixed resin, commercially available V-notched squeegees with notches from 3 to 9.5 mm (1/8 to 3/8 inch) yield approxi-mately 250 µm (10 mils) of coating per each 3 mm (1/8 inch) of “V” depth for resin viscosities approximating that of “motor oil.” Some examples are shown in Table A.1.

Squeegees and notched trowels are available in other notch sizes and configurations that can deliver materials in varying thicknesses. They should be field tested to determine consistent delivery range, as resin viscosity, temperature, fillers and application methods will affect final coverage. In addition, smoothness or substrate planarity will also affect delivered thickness.

Rakes: Rakes are used to initially level the mortar, which is usually an aggregate-filled material, to achieve a final compac-tion of 170 mm (2/3 inch) or greater. Gauge rakes have a cam that can be set at varying elevations to control the thickness of the applied coating.

Trowels: The pressure of a straight-edged metal trowel forces dense aggregate or glass-flake-filled coating products into the pores and voids of concrete to produce a solid, smooth finish. Power trowels are often used because they provide greater compaction and leave fewer trowel marks and ridges.

Screeds and Screed Boxes: Screeds are used to apply material to provide a level finished surface to a specific eleva-tion. Metal screed bars or edging strips are set to the precise height of the finished surface, and the coating is deposited between them. A vibrating horizontal screed can be set on rails to compact the coating material and strike the surface flush with the top of the screed bars.

Most often, screed boxes are used to dispense resinous mortar over a floor surface to a consistent initial thickness. After a section of the floor is overlaid with resinous mortar, it is compacted with hand trowels, power trowels, or other special-ized compaction equipment.

Rollers: Rollers may be used for application of final finish coats. The length of the nap controls the amount of coating delivered to the substrate and the texture of the cured coating. Non-shedding, mohair roller naps are most often used to apply finish coats of 125 µm (5 mils) or less in thickness when used as a stand-alone application technique. Thicker finish coats may be applied by the use of squeegee/backroll technique, by which the material is applied by squeegee, allowed to settle, then rolled out with a non-shedding roller nap. Roller naps should be de-linted by rolling out the nap across an adhesive material such as duct tape. Several roll-out processes may be required until lint and other particles are no longer shed on the adhesive. Disc rollers are longer rollers that fit into a metal frame with a central handle and are used to flatten fabric or mat containing surfacings. Spiked, or “porcupine,” rollers pierce air/vapor pockets and are used to deaerate the applied coating or surfacing material. Looped rollers may also be used to assist in the leveling of self-leveling or slurry applications. These rollers redistribute applied materials and should be used before the materials begin to set.

Spray Equipment: Spray equipment may be used for applications of materials depending upon the material manu-facturer’s recommendations. Pressure, mixing, spray nozzle/gun and other equipment details will vary based upon the requirements of material being applied and the conditions of application.

Table A.1Effect of Notch Depth and Resin Viscosity on Surfacing Depth

Depth of Applied Surfacing Resin Viscosity ApproximatingDepth of Squeegee Notch Water Motor Oil Syrup

3 mm (1/8 inch) 750 µm (30 mils) 250 µm (10 mils) 175 µm (5 mils)5 mm (3/16 inch) 1,125 µm (45 mils) 375 µm (15 mils) 250 µm (10 mils)6 mm (1/4 inch) 1,500 µm (60 mils) 500 µm (20 mils) 375 µm (15 mils)9.5 mm (3/8 inch) 1,875 µm (75 mils) 750 µm (30 mils) 625 µm (25 mils)


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Appendix B: Contractor Walk-Through Guide

The following checklist is a simple guide and recom-mendation for contractors for site observations, notations, questions, and activities that will impact the installation.

1) Project Identificationa) Date, company, address, site description b) Project name and description

2) Environmental Conditionsa) Environmental conditions during installation and

during operationsb) Surface temperaturec) Surface conditionsd) Age and condition of the substrate (concrete)

3) If the concrete is new, find out all pertinent informa-tion regarding the concrete mix, subgrade, vapor barrier, curing conditions, date of pour. Confirm the system that has been selected is compatible with the substrate

4) If the concrete is old, identify as much information as possible with respect to the installation, use, repairs, contaminants and current condition. (See Checklist items below) a) Is there an existing coating, sealer or concrete

curing compound on the floor?b) Will the floor be subject to chemical exposure?

i) What are the chemicals, concentrations, temperature, and duration of exposure (splash & spill, cleaning, immersion)?

ii) Any exposure in excess of 24 hours is gener-ally considered to be immersion conditions. Confirm the system selected is compatible with these service conditions. Utilize coupon testing if necessary.

d) Will the floor be subject to excess heat? Determine locations, durations and temperature.

e) Note and map any physical damage to the floor including cracks.

5) Is the damage due to the operations that the flooring system will be exposed?a) Do the affected areas need to be replaced and

what time frame is available to allow for cure prior to coating?

b) Is the floor wet? Will the service conditions be wet? What is the liquid?

6) What non-slip treatment will be required?

7) Determine the best method and degree of non-slip surface for the required areas. Utilize samples to avoid confusion.a) What is the traffic, abrasion, and impact expected

on the floor?b) For wheeled traffic, what type of wheels and what

weight is expected per contact surface area?8) Based upon the site evaluation, the flooring system

selection can be confirmed to meet all of the condi-tions noted, required repairs can be scheduled, and details for installation can be confirmed with the owner.

9) Installationa) Document Review: Review all product data sheets,

installation procedures, SDS and personal protec-tion (PPE) with owner and installation crew.

b) Site Setupi) Set up all utilities and workspace, including

lighting, ventilation, electrical, and water.ii) Mask and protect all surfaces that may be

exposed.iii) Setup traffic control.iv) Address any leaks, airflows, and other condi-

tions that will adversely affect the installation.v) Setup work station (mix station) and material

storage areas to protect the area and prevent material contamination.

vi) Confirm all waste removal requirements.c) Installation

i) Repair all identified areas.ii) Clean all chemical, oil, grease and other

contaminants that will not be removed with the subsequent surface preparation technique.

iii) Perform surface preparation as required by conditions and system to be installed.

iv) Treat cracks and joints as recommended by the manufacturer of the system to be installed.

v) Vacuum the floor and remove all dust and debris.

vi) Install system per manufacturer’s recommen-dations in stages as agreed to with owner.

vii) Clean the area and remove equipment, masking, waste, empty containers, and cata-lyzed materials that will not be returned to inventory.

viii) Protect the installed flooring system until cured and accepted by owner.

Copyright ©SSPC standards, guides, and technical reports are copyrighted world-wide by SSPC: The Society for Protective Coatings. Any photocopying, re-selling, or redistribution of these standards, guides, and technical reports by printed, electronic, or any other means is strictly prohibited without the express written consent of SSPC: The Society of Protective Coatings and a formal licensing agreement.

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