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  1. 1. Dr. Vaishali.G.Ghorpade, Sri. K. Munirathnam, Dr.H. Sudarsana Rao / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.827-831827 | P a g eEffect of natural rubber latex on strength and workability of fibrereinforced high-performance - concrete with metakaolinadmixtureDr. Vaishali.G.Ghorpade*, Sri. K. Munirathnam**, Dr.H. SudarsanaRao****( Associate Professor, Head Of Civil Engineering Dept., JNTUA College Of Engineering, Anantapur-515002,)**( Research Scholar, J.N.T.U.A, Anantapur – 515002,)***(Professor Of Civil Engineering & Rector, J.N.T. University, Anantapur-515002,)AbstractTo increase the applications of NaturalRubber Latex Modified Fiber Reinforced High-Performance-Concrete (NRLMFRHPC) inIndia, greater understanding of NRLMFRHPCproduced with locally available materials suchas cement , Fine aggregates , coarse aggregates,Metakaolin and Crimped Steel fibers isessential. In the present investigation,NRLMFRHPC has been produced with locallyavailable aggregates and mineral admixture(Metakaolin) and Natural Rubber Latex basedNRLMFRHPC mixes were designed by absolutevolume method. Cubes of 150X150X150 mm indimension were cast and cured for 28 days andthen tested for compressive strength to assessthe strength characteristics of NRLMFRHPC.Workability has been measured by conductingcompaction factor test on fresh NRLMFRHPCmixes. The experimental results indicate thatNatural Rubber Latex can be utilized inproducing durable Fiber Reinforced High-Performance-Concrete. The various resultswhich indicate the effect of Steel Fibers andNatural Rubber Latex on the strength andworkability characteristics of high-performance-concrete are presented in thispaper to draw useful conclusions.Keywords: Metakaoline, Natural Rubber Latex,Steel Fibers, High Performance Concrete.1. IntroductionThe idea that concrete can be strengthenedby fiber inclusion was first put forward by Porter in1910, but little progress was made in itsdevelopment till 1963.The weak matrix in theconcrete, when reinforced with steel fibers,uniformly distributed across its entire mass, getsstrengthened enormously, thereby rendering thematrix to behave as a composite material withproperties significantly different from conventionalconcrete. Generally the ACI Committee Report NoACI 554 Guide for specifying, mixing, placing andfinishing of steel fiber reinforced concrete isfollowed for the design of SFRC mixes appropriateto specific applications. Fiber Reinforced HPC,new generation concrete, results from the additionof either short discrete fibers or continuous longfibers to the cement based matrix. Due to thesuperior performance characteristics of thisconcrete, its use by the construction industry hassignificantly increased. A very good guide tovarious Portland cement-based composites as wellas their constituent materials is available in arecently published book [Balaguru and Shah,1992].The latex modified concrete is defined asPortland cement and aggregate combined at thetime of mixing with organic polymers that aredispersed in water. This dispersion is called a latex.The organic polymer is a substance composed ofthousands of simple molecules known asmonomars. The reaction that combines themonomars is called polymerization. When latex isused in mixes with port land cement, aggregates,and water, fresh concrete is produced withconsistency and workability characteristics onlyslightly different from conventional concrete. Aftercuring, the latex-modified concrete (LMC) consistsof hydrated cement and Aggregate, allinterconnected by a continuous film of latex. It is inpart this continuous film which imparts the superiorphysical and chemical properties to latex-modifiedconcrete [Kuhlmann, 1980]. Some indication ofhow latex systems function to modify the internalstructure of cement paste and concrete has beenprovided by Ohama, [1984]Walters [1990] and Kuhulman [1985]opined that latex modified cement mortars andconcretes are attractive because the latex additionsubstantially increases the flexural strength and thecompressive strength. . On the other hand fiber-reinforced mortars and concretes are attractive
  2. 2. Dr. Vaishali.G.Ghorpade, Sri. K. Munirathnam, Dr.H. Sudarsana Rao / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.827-831828 | P a g ebecause the fiber addition substantially increasesthe flexural toughness and in some cases itincreases the flexural strength and therefore it isappropriate to combine these two methods.Ohama [1973] has studied extensively theproperties and proportioning of polymer modifiedmortars. The same author dealt with the systems inboth mortars and concretes. Polymer dispersionsare added to mortars and concretes to improvecertain desired properties of the final productincluding improved bond strength to concretesubstrates, increased flexibility (ductility) impactresistance, improved resistance to penetration bywater, dissolved salts and improved resistance tofrost action [ Amdur,1988].However due to increasing demand in theconcrete industry to serve the needs of constructionfield, researchers are responding positively byproposing new formulations using other materials.In this Connection incorporating a polymermaterial, Natural Rubber Latex into the concretehas to some extent contributed to this demand inthe society. The reason for usage of polymers in theconcretes is they have good binding properties andgood adhesion with aggregates. They have long –chain structure, which helps in developing long-range network structure of bonding. In contrastcement materials provide short-range structure ofbonding. As a result polymer materials usuallyprovide superior compressive strength to theconcrete. Some polymer materials may selectivelyprovide higher tensile and flexural strength to thestructure compared to compressive strength. Inaddition they provide good adhesion to othermaterial as well as resistance to physical damage(abrasion, erosion, impact) and chemical attack.When the performance of concrete is substantiallyhigher than that of normal type concrete, suchconcrete is regarded as High Performance Concrete(HPC). Concrete may be regarded has highperformance for several different reasons: Highstrength, High workability, High durability-andperhaps also improved visual appearance. For thefirst time in 1932, synthetic rubber (instead ofnatural rubber) latex was used for the latex-modified systems. In 1933, synthetic resin latexes(including polyvinyl acetate latexes) were used inthe modified systems, and by the end of the 1930the inventions clearly suggested that all types ofpolymers (natural or synthetic, elastomers orplastomers) could be used in polymer-modification.Since the late 1940s, latex-modified concretes havebeen used to various applications such as bridges,paving flooring, anti-corrosives, adhesives anddeck coverings for ships. Stevens in 1948 andGriffiths in 1951 conducted feasibility studies onthe applications of natural rubber modifiedsystems. Ohama [1984] investigated the principleof latex modification and some typical properties oflatex-modified concrete. He found the latexmodification improved the properties. Thehardened latex-modified concretes developed goodstrength, adhesion, pore structure, impermeabilityand durability (freeze thaw resistance, chloridepenetration resistance, carbonation resistance andweather ability)In order to achieve the high strength adetailed experimental investigation on Metakaolinbased Natural Rubber Latex Modified FiberReinforced High Performance Concrete(NRLMFRHPC) has been planned. Metakaolin isused as a mineral admixture; Natural rubber latexpolymer is used as an additive. In the production ofHPC polymer based chemical super plasticizers aregenerally used to improve the flow properties andto reduce the water-binder ratio. However in thepresent work, it is proposed to use the naturallyavailable polymer i.e. Natural Rubber Latex (NRL)in the production of HPC and steel fibers of anaspect ratio 50 are added to improve the strengthand durability. The physical properties of eachmaterial which are used in the research program arepresented.2. Experimental ProgramIn order to study the behavior ofNRLMFRHPC and also to understand the effect ofnatural rubber latex on Metakaoline basedNRLMFRHPC, a total number of 81 mixes havebeen tried. In all the mixes the same type ofaggregate i.e. crushed granite aggregate, river sandhas been used. The proportion of cement, sand andaggregate has been maintained same for all mixes.These relative proportions have been obtained byabsolute volume method. Ordinary Portland cementof 53 Grade from a single batch has been used. Thetest program consisted of conducting Compressivestrength test on cubes and workability test on freshconcrete.2.1 Materials2.1.1 CementOrdinary Portland cement of 53 gradesconforming to ISI standards has been procured andthe properties of the cement are investigated in thelaboratory. The cement satisfies the requirementsas per I.S 12269-1987.2.1.2 Fine AggregateThe locally available river sandconforming to grading zone-II of IS 383-1970 hasbeen used as Fine Aggregate. The Specific Gravityof fine aggregates is 2.69 with a fineness modulusof Coarse Aggregatea) The locally available crushed granite materialhas been used as coarse Aggregate. TheSpecific Gravity of coarse aggregate is 2.76and Fineness modulus is 6.99
  3. 3. Dr. Vaishali.G.Ghorpade, Sri. K. Munirathnam, Dr.H. Sudarsana Rao / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.827-831829 | P a g e2.1.4 Steel fibers (S.F)Fiber is a small piece of reinforcingmaterial which has certain characteristic properties.It can be either circular or flat. Plain concretepossesses a very low tensile strength ,limitedductility and little resistance to cracking internalmicro cracks are inherently present in the concreteand its poor tensile strength is due to thepropagation of micro cracks leads to brittle fractureof the concrete. Although every type of fibers aresuitable in cement and concrete not all of them canbe effectively and economically used. Each type offiber has its own characteristic properties andlimitations. The fibers which could be used in theconcretes are steel fibers, polypropylene, nylon,asbestos, coir, glass and carbon. In thisinvestigation crimped steel fibers have been used.The diameter of fibers is 0.6mm and the Aspectratio is Rubber LatexNatural Rubber latex: The NaturalRubber latex is collected from ASSOCIATEDLATEX (INDIA) LIMITED having itsAdministrative Office at P.B. NO.1117, BeachRoad, Calicut. The properties of Natural RubberLatex are presented in Table 1S.No Property Rubber latex1 Colour White2 Total Solid Content (% By Weight) 61.5 Max3 Dry Rubber Content (% By Weight) 60 Min4 Non Rubber solid content 1.50 Max5 KOH Number 0.55 Max6 Ammonia content , NH3 % 0.70 Max7 Mechanical stability time 600 TO 12008 Volatile Fatty Acid Number 0.10 Max9 Magnesium Content 810 PH 10.4 Min11 Coagulum Content , % By Mass 0.01 Max12 Sludge Content, % By Mass 0.01 Max13 Copper content As PPM 514 IRON content As ppm 815 Particle size of Rubber latex 0.2 m16 Specific Gravity of Rubber latex 0.94Table 1 Physical properties of Rubber latex2.1.6 MetakaolinThe mineral Admixture Metakaolin isobtained from VADODARA IN GUJARAT,INDIA. The Metakaolin is in conformity with thegeneral requirements of pozzolana. The SpecificGravity of Metakaolin is 2.6 and its averageparticle size is 1.5 um The Specific surface area is15 m2/gm. The pozzolonic reactivity of Metakaolinis 1050 mg of Ca (oh) 2/2.1.7 WaterClean potable fresh water, which is freefrom concentration of acid and organic substances,has been used for mixing the concrete.3. Fabrications and CastingCubes were cast in steel moulds of innerdimensions of 150 x 150 x 150mm for every mix.The cement, sand and Metakaolin were mixedthoroughly by manually. Then steel fiber is addedto the above mixture. For all test specimens,moulds were kept on table vibrator and theconcrete was poured into the moulds in three layersby tamping with a tamping rod and the vibrationwas effected by table vibrator after filling up themoulds. The moulds are kept in vibration for oneminute and it was maintained constant for all thespecimens. Six cubes were cast for each mix.4. CuringThe moulds were removed after 24 hoursand the specimens were kept immersed in a clearwater tank. After curing the specimens in water fora period of 28 days the specimens were removedout and allowed to dry under shade5. Results and Discussion0.325 0.350 0.375 0.400 0.4250.680.690.700.710.720.730.740.750.760.770.780.790.800.810.820.830.840.850.860.870.88RL 0.00%RL 0.25%RL 0.50%RL 0.75%A/B=2.0, SF=1.00W/B RATIOCOMPACTIONFACTORFig 1 Compaction Factor vs. W/B ratio forMetakaoline based NRLMFRHPC (S.F=1.00)
  4. 4. Dr. Vaishali.G.Ghorpade, Sri. K. Munirathnam, Dr.H. Sudarsana Rao / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.827-831830 | P a g e0.325 0.350 0.375 0.400 0.4256., SF=1.00 RL 0.00%RL 0.25%RL 0.50%RL 0.75%W/B RATIOVEE-BEETIME(SEC)Fig 2 Vee - Bee time vs. W/B ratio for Metakaoline basedNRLMFRHPC (SF=1.00)Observing from Fig 1, it can be noticedthat the compaction factor of NRLMFRHPC mixesincreases with increase in w/b ratio and decreaseswith increase in the percentage of rubber latexindicating a decrease in workability. For 0% rubberlatex at w/b ratio 0.325, A/B ratio 2.0 thecompaction factor observed is 0.76. When thepercentage of rubber latex is increased to o.25%,the compaction factor observed is 0.75. Similarlythe compaction factor at 0.5% of rubber latex is0.74. But further increase in the percentage ofrubber latex from 0.5% to 0.75% the compactionfactor observed is 0.72 which shows that thedecrease in compaction factor is marginal up to0.5% of rubber latex after that the sudden decreasein compaction factor is observed. This indicatesthat the decrease in workability is marginal up to0.5%. Hence in this investigation the percentage ofrubber latex is restricted to 0.5% in order to makeworkable concrete.Observing from Fig 2 it can be noticedthat the Vee-Bee time of NRLMFRHPC mixesdecreases with increase in w/b ratio and increaseswith increase in the percentage of rubber latexindicating a decrease in workability. For 0% rubberlatex at w/b ratio 0.325, A/B ratio 2.0, the Vee-Beetime observed is 8.0 seconds. When the percentageof rubber latex increased to 0.25% the Vee-Beetime observed is 8.5. Similarly the Vee-Bee time at0.5% of rubber latex is 9.0. But further increase inthe percentage of rubber latex from 0.5% to 0.75%the Vee-Bee time observed is 9.4 which shows thatthe increase in Vee-Bee time is marginal up to0.5% of rubber latex after that the sudden increasein Vee-Bee time is observed, which indicates thedecrease in workability up to 0.5% is marginal.Hence it is recommended that 0.5% of rubber latexmay be adopted in order to make workable Fiberreinforced High performance concrete.5.1 Effect of Rubber Latex and Steel Fibers oncube compressive strength of NRLMFRHPCFig 3 Variation of 28-Days CompressiveStrength with % of Rubber latex (R.L) .Fig 4 Variation of 28-Days CompressiveStrength with % of W/B Ratio for 1% of Steelfibers (S.F) .From Fig.3 and 4 it can be observed that theCompressive Strength increases with percentageincrease in Rubber Latex up to 0.5% only. Furtherincrease in percentage of R.L the Compressivestrength starts decreasing. .At 0.5% RL and 1.0%
  5. 5. Dr. Vaishali.G.Ghorpade, Sri. K. Munirathnam, Dr.H. Sudarsana Rao / International Journalof Engineering Research and Applications (IJERA) ISSN: 2248-9622 www.ijera.comVol. 3, Issue 3, May-Jun 2013, pp.827-831831 | P a g eSF with W/B 0.325and A/B =2.0 the compressivestrength observed is 103.67 MPa. The increase inpercentage of rubber latex from 0.5% to 0.75% thedecrease in compressive strength is observed.Similarly the percentage of Steel fibers increasesthe compressive strength is increased. As thepercentage of steel fibers increases from 0.0 % to1.0 %, the compressive strength is increasing.Although the compressive strength is increasedwith the percentage increase in steel fibers, themaximum percentage of steel fibers is restricted to1.0% in order to avoid lumping of fibers duringmixing. Hence it can be concluded that themaximum value of compressive strength isachieved at RL is 0.50% .6. ConclusionsFrom the experimental work carried outand the analysis of the results followingconclusions seem to be valid with respect to theutilization of Natural Rubber Latex and steel fibersin the production of NRLMFRHPC. Compaction factor: workability ofNRLMFRHPC mixes decreases with increasein the percentage of Natural Rubber Latex andsteel fiber It is observed that, at 0.5 % of rubber latex ,the decrease in the compaction factor is verymuch marginal. i.e. about 10.71%. Also it isobserved that these mixes are quite cohesiveeven at lower water-binder ratio of 0.325because of the polymer (Natural RubberLatex) used in the mix. Hence, it can beconcluded that 0.5 % of Rubber latex and 1.0% of steel fiber can be used in the productionof NRLMFRHPC with sufficient workability. The compressive strength of NRLMFRHPCmixes increases up to 0.5% dosage of NaturalRubber Latex. There after a decrease incompressive strength is observed. The 28-day compressive strength ofNRLMFRHPC mixes increases with increasein percentage of Rubber latex up to 0.5%. Itcan further be observed that the maximumcompressive strength of 103.67 MPa isachieved at 0.5 % dosage of natural rubberlatex and 1.0 % of steel fiber at water binderratio of 0.325.References[1] ACI Committee 440. 1996. State-of-the-Art Report on Fiber Reinforced Plastic(FRP) for Concrete Structures (ACI440R). ACI Manual of Concrete Practice,Part 5, American Concrete Institute,Detroit, MI, 68 pp.[2] P. N. Balaguru and S. P. Shah. 1992.Fiber Reinforced Cement Composites.McGraw-Hill, New York, 1992[3] Kuhlmann, L.A [1981] performanceHistory of Latex-Modified ConcreteOverlays, Applications of polymerConcrete, ACT SP-69,1981,ppt 123-144.[4] Ohama, Y, "Chapter 7, Polymer-ModifiedMortars and Concretes”, ConcreteAdmixtures Handbook, Properties,Science, and Technology, Editor: V.S.Ramachandran, Noyes Publications, ParkRidge, New Jersey, 1984, p.[5] Bhatty, JI. J Gajda, PE. Botha, F. andMM Bryant, PG. 2006. Utilization ofDiscarded Fly Ash as a Raw Material inthe Production of Portland cement. Journalof ASTM International, Vol. 3, No. 10,pp.[6] Goh, Chia-Chia., Show, Kuan-Yeow andCheong, Hee-Kiat. 2003. Municipal SolidWaste Fly Ash as a Blended CementMaterial. Journal of Materials in CivilEngineering, Vol. 15, No. 6, pp. 513-53-23.[7] Gopalakrishna, S., Raja mane, N.P.,Neelamegam, M., Peter, J.A. andDattatreya, J.K. 2001. Effect of partialreplacement of cement with fly ash on thestrength and durability of HPC. TheIndian Concrete Journal, pp. 335-341.[8] Hassan, K.E., Cabrera, J.G., and Maliehe,R.S. 2000. The Effect of MineralAdmixtures on the Properties of High-Performance Concrete. Cement &Concrete Composites, Vol. 22, pp. 267-271.[9] Isaia, G. C., Gastaldini, A. L. G. andMoraes, R. 2003, Physical and pozzolanicaction of mineral additions on themechanical strength of high-performanceconcrete, Cement & Concrete Composites,Vol. 25, pp. 69-76.[10] Jerath, Sukhvarsh P.E. and Hanson,Nicholas. 2007. Effect of Fly Ash Contentand Aggregate Gradation on theDurability of Concrete Pavements. Journalof Materials in Civil Engineering, Vol. 19,No. 5, pp. 367-375.[11] Long, Guangcheng. Wang, Xinyou andXie, You Jun. 2002. Very-High-Performance Concrete with Ultra-finePowders. Cement and Concrete Research,Vol. 32, pp. 601-605.[12] Uzal, B. and Turanli, L. 2003, Studies onblended cements containing a high volumeof natural Pozzolans, Cement andConcrete Research, Vol. 33, pp. 1777-1781.[13] Wang, Shuxin and Li, Victor C. 2007.Engineered Cementitious Composites withHigh Voume Fly Ash, Materials Journalof ACI, Vol.104,No.3,pp.233-241