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SBEIDCO 1st International Conference on Sustainable Built Environment Infrastructures in Developing Countries

ENSET Oran (Algeria) - October 12-14, 2009

T2.How Nanotechnology Can Change Concrete Industry S.I Zaki, Khaled .S. Ragab

407

HOW NANOTECHNOLOGY CAN CHANGE CONCRETE

INDUSTRY

S.I Zaki* and Khaled .S. RagabHousing and Building National Research Centre, Cairo, Dokki, Egypt

T. 2. Performance of materials

ABSTRACT

In recent years, the world of science has started to produce new materials and to research their properties withnanotechnology. The use of nanotechnology has become wide spread in all branches of science. So, studies of

nano-scale should be increased for concrete technology. In this study, the use of nano powders in concrete in the

world have been summarized and evaluated.

The influence of nano particles such as silicon dioxide added to polymers mixed in concrete was studied for both

high-performance and self-compacted concrete with reference to normal size particle concrete.

The progress from sulphonated polymers to polycarboxylate was studied and has resulted in higher water

reduction and higher strength.

Also, the influence of nano particles on the properties of fresh and hardened self-compacted concrete are studied

in comparison with normal size ones.

The morphology of nano particles was studied using Transmission Scanning Election Microscopy (TEM).

Also, X-ray diffraction (XRD) of all the mineral additions was studied.

The results indicated that the addition of nano particles improves the properties of concrete.

KEYWORDS:

Nano - composites, nano - SiO2, SCC, HPC, polycarboxylic

*Corresponding author: [email protected]

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1. INTRODUCTION

During the period of the second half of the previous century, the terms "nano-science" and "nono-technology" were not yet familiarly used as today, however they were really practiced andsuccessfully applied to the progress in the field of material science and technology. Concreteperformance is strongly dependent on nano-size dimensions of solid material such as C-S-H particlesor voids such as the gel porosity in the cement matrix and the transition zone at the interface of cement paste with aggregate or steel reinforcement, typical properties affected by nano-sized particles arestrength, durability, shrinkage and steel-bond. The word nano means anything of size 10-9, nanoparticles is a solid particle of having size in the range 1 to 100 nm. The purpose of the present work is

to study a new material in the dimension range between "micron " and " nano " size , this material isnano silica (Nano-SiO2) which added to new super plasticizer (polycarboxylic ether polymerd basedPCE Sky) to improve workability , strength , flexibility and durability of high-performance and self-compacted concrete. There are few studies on the application of nano-technology in concrete production summarized below: Collepardi S. et al., studied the influence of nano-sized mineraladditions on performance of self-compacted concrete and found that Poly-functional super plasticizersare able to keep the initial slump for at least 1.0 hour without any retarding effect on the early strengthand also reduce drying shrinkage. Soblev K. et al. used polycarboxylic ether polymer based PCE Sky

mixed with nano Si02 to improve workability and strength of high-performance and self-compactedconcrete. Ferrada M.G. Studied the use of commercial nano admixture for concrete called Gaia tosubstitute for silica fume at ready-mixed and achieved two fold increase in concrete compressivestrength at the age of 7 and 28-days , he used cement content 460 kg/m

3at ambient temperature 20C.

Sobolev K. and Ferrada M.G., studied the application of Gaia super plasticizer containing nano-SiO2particles at a dosage of 1.3% by weight of cementitious materials and found that there is an increasein concrete compressive strength (100-150) % at the age of 7 and 28 days when used the above superplasticizer mixed with nano Si02 and this dependent on w/c ratio. Remzi S. and Meral O., made aliterature review on the researches studied the effect of nano powders on cement paste, mortar andconcrete and found that the use of nano powders in concrete technology affects the cement kinetics

and accelerates hydration significantly due to larger surface area, stronger electrostatic forces of nano powders, and due to improvement in the microstructures of concrete having nano powders. Li G.

studied the properties of high volume fly ash concrete incorporating nano-SiO2 and found that theaddition of nano-SiO2 can activates fly ash, leads to an increase of both short-term and long termstrength, and acts as an accelerating additive leading to more compact structure even at short curing

times. Zhang G. studied the effect of blending CPE (carboxylic polymer ether) to nano-SiO2 and foundthat the addition of nano-SiO2 to CPE polymer increases strength, flexibility and aging resistance sincenano-SiO2 interpenetrates polymer networks. Hui Li studied the flexural fatigue performance ofconcrete containing nanoparticles (nano-SiO2 and nano-TiO2) for pavements and found that thefatigue of concretes containing nano - particles follows the double parameter weibull distribution ,the flexural fatigue performance of concretes containing nano-particles is improved significantlyespecially when contained nano-TiO2 in the amount of 1% by weight of binder, which is much better

than that of concrete containing polypropylene fibers (PP) which has been extensively used to improvefatigue performance of concrete pavements. Sobolev K. carried out an investigation study nano

materials and nanotechnology for high-performance cement composites and found that the major problem of nano-SiO2 application is strength loss at later ages due to the agglomeration of nanoparticles (30-100 nm) at the final drying stage of sol-gel method which can be solved using acrylic

polymer based super plasticizer called Gaia at a dosage of 1.3% by weight of cementitious materials ,also Sobolev K. found that high-temperature treatment at (400c or more) of nano-SiO2 concrete

affects the performance of these additives and must be avoided. Jorge IV (10) carried out aninvestigation about Portland cement blended with nano particles and found that nanotechnology is anew topic in cement industry to produce high performance concretes , since there is mineralogy

modifications of cement paste and mortars occurred due to the incorporation of nano particles likenano-SiO2, nano-Tio2. R. Abbas carried out an investigation to study the influence of Nano-Silica

addition on properties of conventional and ultra-high performance concretes and found that nano-Silica (NS) concretes requires additional amount of water , since each kilogram of NS added required0.4 kg of water to maintain the same workability, also nano-silica addition resulted in significant earlyincrease in compressive, splitting and flexural strengths of concrete in case of high cement content and

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low w/c ratio . Also, addition of 5% nano-silica leads to an increase 50% in 7-day compressivestrength and 40% in 28-day compressive strength when compared with the same concrete withoutnano-silica.

2. EXPERIMENTAL WORK

In this work, the well known performance of concrete without nanoparticles was compared with thatafter the addition of nano-particles for both fresh and hardened states.

2.1. Materials

The cementitious materials used during this study were OPC, silica fume, nano-silica.Ordinary Portland cement (OPC) was used of type (CE M1 42.5N) according to E.S.S. (4756-1-2006)obtained from Beni-Suef cement Factory in Egypt.Silica fume was obtained from Egyptian Company for Iron Foundries, while nano Silica was exportedfrom Sigma-Aldrich Company in Germany through International Egyptian Center for Export.Polycaboxilate-based super plasticizer (30% in aqueous solution) was used in comparison withsulphonate naphthalene super plasticizer to produce self-compacting concrete (SCC) with relativelylow water-cement ratio.

2.1.1. Ordinary Portland Cement (OPC). Chemical analysis of OPC is shown in Table (1).2.1.2. Silica Fume. Silica fume is a very fine by-product powder obtained as a fume from the foundry process in the Egyptian Company for Iron Foundries. Figure (1) shows the morphology of SF bytransmission scanning Electron Microscopy (TEM) carried out in the National Research Center. Table(2) shows the physical properties of used Silica fume.

2.1.3. Nano Silica.NSF is synthetic product with spherical particles in the range of 1-50 nanometers.It has already been studied as viscosity modifying agent in combination with super plasticizers in orderto produce high performance SCC, the product used in this study is colloidal silica water emulsion

(30% dry solid with particle size distribution of the solid material in the range of 5-15 nm.The chemical analysis shows that it consists mainly of pure silica (>99%) dispersed in an aqueous

phase as shown in Table (1). Table (3) shows the physical properties of used NSF. Figure (2) showsthe morphology of NSF. Figure (3) shows the XRD patterns of the mineral additions (SF and NSF).The X-ray diffraction patterns (XRD) indicated that the crystalline behavior of both nano-Si02 and

silica fume is low and the used nano-Si02 is a highly amorphous material.

Table 1.Chemical Composition of Cementitious Materials

% OPC SF NSF

Si02 19.8 93 99.1

A12O3 5.5

CaO 63 0.2

MgO 1.18

Fe2O3 3.39 0.3

Na2O 0.46

K2O 0.16

SO3 3.01 0.1

LOI , Loss of Ignition 5.2 2.0

Table 2.Properties of silica fume

Description Results

Particle Size (nm) 34

Surface area (m2/gm) 14

Density (g/ cm3) 2.22

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Table 3.Properties of Nano-silica

Description Results

Particle Size (nm) 24

Surface area (m2/gm) 200

Density (gm/cm3) 0.505

Molecular SiO2

Molecular weight 60.08

2.1.4. Superplasticizer

Sulphonated naphthalene base super plasticizer (Plastmix F) was used in the first part of theexperimental work of this study , then polycarboxylic ether polymer based PCE SKY was used in thesecond part of this study ( Glenium ACE 30 and Glenium SKY 510).The first super plasticizer (Plastmix F) was obtained from Construction Chemicals Expertise Companyin Egypt, while the second super plasticizer (Glenium) was obtained from BASF chemical company inEgypt.

2.1.5. Aggregates2.2. Concrete Mix Design With And Without Nano Particles

Self-Compacting concretes (SCC) have been manufactured with and without nano particles in ordercompare the well known performance of SCC without nano particles with that with nano ones. So ,self-compacting concretes with a binder content of 550 kg/m3 were manufactured in all concretemixes as shown in table (4-a) and (4-b) , the water binder ratio was the same for concrete mixes equal0.39 for mixes M1 to M5 while 0.35 for mixes M6-M10.

A proper dosage of super plasticizer 6 lit/m3 for mixes M1 to M5 as shown in table (4-a) and was 10lit for mixes M6 to M9 as shown in Table (4-b).SCC was characterized in fresh state during this study using slump-flow and J-ring tests since the twotheological measurements are suitable for both laboratory and site application.The composition of self-compacting concretes with and without NSF is shown in table (4-a) in case of

using lignosulphonate super plasticizer.M1 is control mix No. (1) without SF or NSF , while M2 is control mix No.(2) in which 100 kg of

cement was replaced with 100 kg of SF.Table (4-b) shows the same composition in case of using polycarboxyate super plasticizer. Nano-Silicawas added in three percentages (0.5, 0.7and 1%) of weight of cementitious materials (cement and SF).

Natural sand of size (0-4 mm) was obtained from pyramid quarry in Egypt, while the coarse aggregatewas dolomite obtained from Attaka quarry in Egypt; two nominal maximum sizes were used during

this study: Aggregate 1 of size (4-20) mm and Aggregate 2 of size (20-40) mm.

Table 4-a.Composition and properties of SCC in the fresh state with and without NSF usinglignosulphonate superplasticizer

Description Control Nano zero% Nano 0.5% Nano 0.7% Nano 1%

Mix. No M1 M2 M3 M5 M4OPC kg/m

3550 450 450 427 450

SF 100 100 100 100

NSF 2.75 3.5 5.5

Sand 760 760 760 780 760

Dolomite 760 760 760 855 760

Water 211 220 220 190 220

Superplasticizer. 3.5 6 6 6 6

Slump flow(cm) 70 56 46 39 37

J-ring(cm) 56 50 44 35 32

T50 (sec.) 2 5 7

w/p 0.38 0.4 0.397 0.388 0.396

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Table 4-b.Composition and properties of SCC in the fresh state with and without NSF usingpolycarboxylate superplasticizer

Description Control Nano zero% Nano 0.5% Nano1% Nano 0.7%

Mix. No M6 M7 M8 M9 M10OPC kg/m

3550 450 450 450 450

SF 100 100 100 100

NSF 2.75 5.5 3.5

Sand 575 575 575 575 575

Dolomite 1070 1075 1075 1075 1075

Water 192.5 192.5 192.5 192.5 192.5

Superplasticizer. 10 lit 10 10 10 10.0

Slump flow(cm) 53 57

J-ring(cm)

T50 (sec.)

w/p 0.35 0.35 0.35 0.35 0.35

2.2.1. Mixing Procedure. The cement , fine aggregate , coarse aggregate and silica fume were dry

mixed in a rotary mixer for 30 sec. , then 80% of mixing water was added and mixed for 30 sec. , thena ready-mixed liquid including super plasticizer and nano-Si02 was added to the 20% remained waterand then the liquid poured into the rotary mixer slowly . The concrete mixture was mixed wet foradditional 1.5 min.

2.2.2 Testing Procedure. After mixing , slump flow and J-ring tests were carried out to measure theproperties of self-compacted concrete (SCC) according to standard specifications for testing SCC (12), then the well-mixed concrete mixture of each mix was poured into twelve standard cubes ofdimensions 15x15x15 cm for each mix , Five concrete mixes were cast for both lignosnlphonate super

plasticizer mixes (M1 to M5) , and polycarboxylate super plasticizer mixes (M6 to M10) , cubes weredemolded after 24 hrs and then cured in standard curing tank until the age of testing , where , cubes

were dried in air for one hour before testing and then tested three cubes after 7 , 28 , 90 and 365 days.

2.3. Scanning Electron Microscopy SEM

Scanning Electron Microscopy was carried out in Natural Research Center at Physics Department forTransmission Scanning for powders (SF and NSF) and the data of microscope is :-

Transmission Electronic Microscopic type JEOL JEM 1230 of magnification up to 60000 made inJapan was used for powders (SF and NSF).It can be observed that nano-Si02 particles are represented by highly agglomerated clusters with thesize of 24-32nm. Scanning Electron Microscopy was also carried out in the same National ResearchCenter Central Laboratories for Services for concrete samples with and without nano Si02 using

Electronic Microscope type JEOL JXA-840 A, OXFORD, of magnification 5000 and 6500.The specimens were cut directly from concrete cubes, the shape of specimens was regular and the

surface was flat.

Table 5-a.Properties of hardened concrete with and without nano particles using lignosulphonatedsuperplasticizers.

Mix No. Mix descriptionCompressive strength kg/cm

2

7-day 28-day 90-day 1-year

M1 Control 450 550 560 700

M2 nano SiO2 0.0% 501 566 600 740

M3 nano SiO2 0.5% 472 578 622 800

M4 nano SiO2 1.0% 442 467 580 644

M5 nano SiO2 0.7% 442 545 590 750

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Table 5-b.Properties of hardened concrete with and without nano particles using ploycarpoxylatesuperplasticizers.

Mix No. Mix descriptionCompressive strength kg/cm

2

7-day 28-day 90-day 1-year

M6 Control 614 720 800 1000

M7

nano SiO2

0.0% 640 750 840 1050

M8 nano SiO2 0.5% 700 800 900 1150

M9 nano SiO2 1.0% 650 720 800 1020

M10 nano SiO2 0.7% 680 780 870 1100

Fig.6 (a, b) shows the electronic scanning photographs of control sample without nano-Si02 which

magnify the microstructure 5000 and 6500 times.Fig. 7 (a, b) shows the electronic scanning photographs of nano-Si02 concrete samples which magnifythe micro structure 5000 and 6500 times.

2.4. X-Ray Diffraction

The particle size distribution of SF and NSF was measured in HBRC at Raw Building Materials

Technology and Processing Research Institute Laboratories using diffraction scattering particle sizedistribution analyzer Horiba AL-950.

Figure 1. a, b. TEM micrograph of SF

Figure 2. a, b. TEM micrograph of NSF

3 ANALYSIS AND DISCUSSION OF TEST RESULTS

3.1. Compressive Strength

Table (5-a) and Fig.(4) show the compressive strengths of concrete with and without nano-particlesusing lignosulphonated super plasticizer . It can be seen that compressive strength of concrete withnano-particles was improved at 28-days up to one-year and the optimum amount of nano-Si02 is 0.5%by weight of the cementitous material content. Table (5-b) and Fig.(5) show the compressive strengthsof concrete with and without nano particles using polycarboxylate super plasticizer . It can be seen

also that compressive strength of concrete with nano particles was improved at 28-days up to one-yearand the optimum amount of nano-Si02 is 0.5% also, but the strength level for polycarboxylate nano

concretes is (43-48) % higher than lignosulphonate nano concretes, this is due to improvement in the

activity of nano-Si02 when polymcarboxylate super plasticizers are used.

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3.2. Microstructure

To verify the mechanism predicted by the compressive strength test, SEM examinations wereperformed. Additions of nano-Si02 particles were found to influence hydration behavior and lead todifferences of the microstructure of hardened concrete Fig. (6) Shows SEM micrograph of controlsample (without nano-Si02) after one-year with magnification of the microstructure 5000 times infig.(6-a) and 6500 times in fig. (6-b). It can be seen that calcium silicate hydrate (C.S.H.) existed inisolated points surrounded by many needle-hydrates, on the other hand the microstructure of themixture containing nano-Si02 of amount 0.5% by weight of cementitious materials revealed a dense ,compact formation of hydration products (C-S-H) as shown in fig. (7)-(a) and (b) , since the texture of

(C-S-H) of nano-Si02 concrete is very dense , compact and with big crystals.

Position [2Theta]

10 20 30 40 50

Counts/s

0

10

20

30

40

0

20

40

SF

N-Si

Figure 3. XRD patterns of the mineral additions (SF and NSF)(a) Nano-SiO2 (b) Silica Fume

Figure 4. Development of concrete strength with time using lignosulphinated superplasticizer.

Figure 5. Development of concrete strength with time using polycarboxylate superplasticizer

(a) (b)

Figure 6. SEM micrograph of control sample after one year.

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(a) Magnification 5000 (b) Magnification 6500

Figure 7. SEM micrograph of Nano SiO2 Concrete sample after one year.

4. Conclusions and RecommendationsThe properties of concrete are improved by the use of nano powders, since nano particles fill the voids between cement grains and also consume a part of calcium hydroxide which results in additionalformation of calcium silicate hydrate (C.S.H.) and more improvement of interface structure.

The application of nano SiO2 particles with newly developed super plasticizer (polycarboxylic ether polymer based PCE sky) improved the workability and strength of high performance and self-

compacted concrete since nano-SiO2 interpenetrates polymer network, and causes the aboveimprovements.The progress from sulphonated polymer to polycarboxylate has resulted in higher water reduction at agiven workability, lower slump loss and (43-48) % higher compressive strengths, according to theindicated results.

The efficiency of nano particles such as nano-Si02 depends on their morphology as well as theapplication of effective super plasticizers which help to disperse formation of agglomerates andimprove concrete strength.Nan particles, such as nano silica dioxide (Nano-SiO2) were found to be very effective when mixedseparately with super plasticizer (polycarboxylate base) and then added to the 20 % remained ofmixing water as mentioned in mixing procedure. Nano-Silica concrete requires additional amount of water or super plasticizer to maintain the sameworkability level.Nano-Silica addition results in significant increase in concrete compressive strength after 28-days upto one year and the optimum amount of nano silica is 0.5% by weight of cementitious material.

REFERENCESCollepardi S.etal.,Influence of nano-sized Mineral additions on performance of SCC6th International

Congress, Global Construction, Ultimate concrete Opportunities, Dundee, U.K., July 2005.

Sobolev K., et al., "How Nano technology can change the concrete world", American Ceramic Society Bulletin,

Vol. 84, No. 11, Nov. 2005.

Ferrada M.G., et al., " U-Silice ISO 14001: Silice a Favor del Media Ambiente, " XIV Jornalas Chilenas del

Hormigon, Valdivia, Chili, 2003.

Sabolev K., and Ferrada M.G." Nano-technology of concrete, http:// www.nano-cement.50 webs.com

Remzi S. and Meral Q, " New Materials for concrete Technology: Nano powders ", 33rd conference on our

world in concrete & structures, Singapore, 25-27 August 2008, pp (399-406).

Li, G "Properties of high-volume Fly ash concrete in corporating nano-SiO2" Cement and Concrete Research,

vol. 34, No.6, Jun. 2004, pp 1043-1049.

Zhang Q. et al.,"Study on the CPE / Nano SiO2blends,"Journal of function polymer 15(3), 2002, pp 271-275.

Hui Li et al., "Flexural Fatigue performance of concrete containing nano particles for pavement", International

Journal of fatigue, Nov. 2006.

Soblove K. et al., "Nano materials and Nano- technology for High-performance cement composites",

Proceedings of ACI Session on "Nano technology of concrete", Nov. 2006, Denver, USA.

Jorge IV et al., "Portland Cement Blended with Nano particles", Revista DYNA, Universidad Nacional de

Colombia sede Medellin calle 59 A No. 63-20, 2006.

R. Abbas , " Influence of Nano-Silica addition on properties of conventional and ultra-high performanceconcretes " , HBRC Journal , vol.20, No. 20, April 2009, p.p. (1-13).

Egyptian Technical specifications for self-compacted concrete, Ministerial Decision no. 360, 2007.

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