Role Of Admixtures In Concrete Durability

CONFIDENTIALRole of admixtures inconcrete durabilitySaudi Concrete Conference, May 2016David Bowerman, RBSM AS & CA, ORA

CONFIDENTIALPresentation objectiveTo demonstrate how admixture technologycan improve the quality of concrete toconstruct more sustainable structuresRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALDurable concrete?Low water/cement ratioSupplementary cementitious materialsDense reinforcement?Able to pump?Able to place?Able to finish?RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALDurable Concrete?RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALRheology of ConcreteRheology defines the flow and intrinsic behavior of materials (from Greekrhéō, "flow" and -logia, "study of")“Rheology retention” expresses the ability to maintain these properties overan extented time.Scientifically the rheology of the concrete is measured using a rheometerBingham fluidIntrinsic characteristicsτ t0 ηγ t0 : yield point; minimum shearstress to initiate the flow η : plastic viscosity; slope of theshear stress curve vs. shear rate t : Yield stress γ : shear r-builderssolutions.basf.aeRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALEvaluation of rheology ICAR rheometerMeasuring intrinsic characteristics t0 : yield point; minimum shear stress to initiate the flow η : plastic viscosity; slope of the shear stress curve vs. shear rateRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALNext generation polymersConcreteperformancedevelopment of 19902008PlasticHigh slumpSelf-compactingconcreteconcreteconcreteRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALPoly Aryl Ether (PAE)First new superplasticiser technology for 20 yearsPatented technologyMuch less sticky than any PCE (improved rheology)RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALPerformance objectivesfor new polymerMaintain all the advantagesof PCE technology: water reduction, workability retention, early strength, Sharply decreases the yield stress and plastic viscosity of concreteYield stress [Pa]referencemixPlastic viscosity -30%AirPCEnewpolymerPlastic viscosity [PA s]Conventional PCENew PolymerRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALWater is good for rheology but .An increase in the dosage of waterwill have a direct impact on themechanical performanceDurability lders-solutions.basf.aewww.master-builders-ideal 20% 33%solutions.basf.aeW/C 60%water additionThere is a directlyaffect on the porosity10152025 100%30150 160 170 180 190 200 210 220 [l/m3]0.430.510.570.65 W/BRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALPerformance optimisationObjectives:Possibility to reduce the w/c ratio withoutaffecting the viscosity of concreteEnsure maintenance of handling andmaintaining low viscosity over the entiretime of delivery and placement (“rheologyretention”)Whilst at the sametime improving:The robustness of concreteDurability of concrete (strength,shrinkage, porosity, etc)Mix design optimisations withoutcompromising on rheology: Higher SCMusage and/or reduced cement. Use ofchallenging aggregates.Improved concrete surfacesRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALLow viscosity concreteutilising PAESame mix design; same slump/flowOnly difference is admixtureRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALLow viscosity concreteutilising PAEIdenticalmix designIdenticalslump flowRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALLow viscosity concreteutilising PAEIdenticalmix designandidenticalslump flowRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALLaunch of new polymerRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALAdvantages of PAEReduces pumping pressureReduced pumping timeImproved truck utilisationReduced wear and tear on pumpsIncreased life of pipelinesConcrete easier to place and finish enabling thedurability designed into the mix to be realisedRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALAdmixtures forenhanced durabilityShrinkage reducing admixturesCrack reducing admixturesCorrosion-inhibiting admixturesAnti-microbial admixturesWaterproofing admixturesRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALCrystalline waterproofingadmixturesSealingcracks up to0.4mmRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALHydrophobic poreblocking admixturesNational Dubai, OPCTotal Free Water( Added In Admixtures )Free W / Cm RatioSuperplasticiser dosage l/m3 ( l/100kg Cm )Waterproofer dosage l/m3 ( 1/100kg Cm )Date of TrialConcrete Temperature 0CWorkability bySlump mmInitial30min60minAir Content %Fresh Wet Density kg/m3BS 5075 Set TimeInitialhrs : minsFinalCompressive Strength N/mm224hrs3day7dayBS 1881 Pt 122 Water Absorption7day400160( 157 3 )0.404.95( 1.238 )-----30-6-0229.0170135100400160( 150 10 )0.405.15( 1.288 )8.0( 2.0 .02.524906:458:0023.041.549.560.02.5 %0.75 %RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALMicrobiologically Induced Corrosion (MIC)3. Sulfuric acid (H2SO4) is a strongacid that corrodes the concretestructure2. Air breathing bacteria(Thiobacillus) in the sewerage systemconvert H2S into sulfuric acid (H2SO4)1. Non air breathing bacteria in theraw sewerage produce hydrogensulfide gas (H2S)RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALEffects of Micro-organisms on ConcreteMicrobiologically Induced Corrosion (MIC)RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALAnti-Microbial Admixture (AMA)How Does It Work?1. Anti-Microbial Admixture (AMA) integratespermanently into the concrete structure2. Micro-organisms come into contact with theconcrete surface and are destroyed3. The AMA prohibits further growth of microorganisms4. The result - a clean concrete surface free of thegrowth of mold, algae, fungus, viral, andbacterial organisms for the life of the concreteRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALFeatures & BenefitsWater-based, non-flammableNot harmful to the environment, safe forproducers and contractors to handleCan be used in all concrete applicationsto prevent growth of micro-organisms(precast, manufactured concreteproducts, cast-in-place, shotcrete,underground constructions, etc.)No impact to plastic or hardenedconcrete properties (air, set time,strength, etc.)U.S. EPA RegisteredCompatible with other admixtures forconcreteRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALWhy do we need corrosioninhibiting admixtures?Concrete frequently fails to meet its design life;especially in marine environments.RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALWhat is a corrosion inhibitor?An inhibitor is a substance which retards or slowsdown a chemical reaction. Thus, a corrosioninhibitor is a substance which, when added to anenvironment, decreases the rate of attack by theenvironment on a metal.Corrosion Basics, An Introductionpub. National Association of Corrosion Engineers (NACE)RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALCorrosion inhibitingadmixturesGive protection against corrosion of steel in reinforcedconcrete structuresGood for structures exposed to cycles of wetting anddrying (e.g. structures in a marine environment)Do not prevent corrosion completelyDo delay the time when corrosion startsDo delay the rate at which corrosion occursRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALService life of a reinforcedconcrete structural elementBenefit of C.I.AdmixtureCORROSIONLIMIT OF SERVICE LIFECO2 and Cl-penetration concrete quality INHIBITIONINITIATIONti& environmenttpLIFETIME OF THE STRUCTURAL ELEMENTRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALDual mechanism organiccorrosion inhibitors1) Reduce permeabilityof concrete2) Form a pacifying layeron steelSingle dosage independentof chloride level RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALLife-cycle p://www.life-365.org/download.htmlRBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALSummaryYes; specify durable concrete. But Enhance the rheology to make the mix : Easier to pump Easier to place and compact (preferably SCC)Easier to finishThen extend the service life of the structure byadding durability-enhancing admixtures.RBSM Aug 2012 OMM 10Aug12.pptx

CONFIDENTIALThank you for your attention.

Anti-Microbial Admixture (AMA) How Does It Work? 1. Anti-Microbial Admixture (AMA) integrates permanently into the concrete structure 2. Micro-organisms come into contact with the concrete surface and are destroyed 3. The AMA prohibits further growth of micro-organisms 4. The resul