Effect of Formulation Parameters on Adhesive Properties of ...

1 Effect of FormulationParameterson AdhesivePropertiesof TileAdhesiveMortars imsaCement ResearchandApplication CenterAugust, 2017 Thefactorsaffectinginterfacialresistance betweentilesandpolymermodifiedcementmort arsare: Ceramictilewaterabsorption, Cementamountandcomposition, Theamountandtypeofpolymer, Installationprocedures, Theyaregenerallyvinylacetate-based(VA)wi thpolyvinylalcohol(PVA)thatisspreydriyin gagent. ;suchasconcrete,sceramic,wood,vitrifiedg lassbytheirhydroxylgroupsontheirsidechai ns. Bothpolyvinylalcoholandvinylacetate-base d(VA) ,theyarecopolymerizedwithhydrophobicpoly merusuallywithethyleneorvinylversatate(V eoVa).Latex PolymersEffect of Chemistryof theRedispersibleLatexPowder(RDP) in Use ToinvestigateeffectofchemistryoftheRDP,t hesameamount(2wt%)VA/VeovaorEVA-basedred ispersiblepowder(RDF)wereused.

2 Nosaggingwasobservedonbothmortarsprepare dwithVA/VeovaorEVA-basedRDF. Themeasuredviscositieswereof76,000and70, 000mPas,indicatingthatworkabilitydoesnot changewithdifferenttypesofpolymericpowde redresin. ThemortarformedwithVA/VeoVAperformedextr emelywellat20minandbondstrengththreetime shigherthantheminimalrequirementof75psi( )becauseofhydrophobicsidechainoftheVeoVA copolymer. Afterparticlecoalescenceandfilmformation ,waterevaporationduringthe28daysdecrease sandprovidesbetterhydrationofcementatear lyage,promotingmechanicalanchoringoftheC -S-Hgelfromcement' of Chemistryof theRedispersibleLatexPowder(RDP) in UseEffect of Chemistryof theRedispersibleLatexPowder(RDP) in Use Thepolymer ,delayedfilmformationuponC-S-Hgelwiththe VA/Veovacopolymerco-matrixformationatane arlyage(1day)isobserved.

3 Asseenfigure2,EVAbasedmortarsexhibitshig herinitialshearstress(1day) of Chemistryof theRedispersibleLatexPowder(RDP) in UseEffect of Chemistryof theRedispersibleLatexPowder(RDP) in Use Weff:massofefficientwater Nosaggingwasobserved,andthemeasuredvisco sitieswere76,000and100, , of CementDosageat ConstantWeff/C Ratio In mix 2, The increase in viscosity with decreasing cement can be becauseof additionof starchether. Hydrocolloidsrate increasesfrommix 1( wt%) tomix 2 ( %) Duetothehigh hydrocolloidsrate in mix 2, opentime performanceis betterthanmix 1 Effect of CementDosageat ConstantWeff/C Ratio Highershearstressvalueswereobtainedonthe mixdesign1duetohighercementcontentatearl yages(upto7days,independentlyofthecuring conditions).

4 At28days,shearstressvaluesoftwomortarsex hibitssimilarintermsofco-matrixdevelopme ntbothmortars of CementDosageat ConstantWeff/C RatioEffect of CementDosageat ConstantWeff/C RatioEffect of the CelluloseEtherContent Mortarsviscositiesmeasuredas38,000,50,00 0and54, , , Ifhydrocolloidsamountislow, ,enoughwaterforhydrationcannotbeprovided becauseofevaporationwhichresultsdecrease inbondvalues. Ifhydrocolloidsamountishigh, of the CelluloseEtherContent Maximumopentimeperformanceisobservedonam ortarproportionedwithoptimumhydrocolloid srate( ). Effect of the CelluloseEtherContent Whenthehydrocolloidsrateislow,afullconta ctbetweenthemortarandthetiletakesplace,l eadingtobettershearstressvalueswithatear lyages(1day). After7days,thereisnotenoughwaterretainin gadmixtureinthemixturetoreleaseenoughwat erinordertopermitgoodhydration,resulting inlowshearstressvalueswhenmortariscurede itheratroomtemperatureorat70 of the CelluloseEtherContent Whenthehydrocolloidsrateishigh,1dayshear stressvalueislowbyretardingthehydrationo fcement(waterentrapment), of the CelluloseEtherContentAnoptimumdosageofhy drocolloidsshouldbefoundtobalancethesetw oeffects, of the CelluloseEtherContentEffect of the RDP Content ViscositiesdecreasedwithincreaseofRDPval uefrom2to3(wt%)duetoplasticizingeffectof RDPinfreshmortar.

5 AlsoduetowaterretentionefffectofRDP,thew ettingabilitywasslightlyenhancewithincre aseinwt%ofRDP.(%70ofcovarageembeddedinth eCTA30min). Allofthematerials(RDP,starchetherandcell uloseether) IncreaseinRDPcontentcausesdecreaseinopen timeperformanceasseenfigure10. of the RDP ContentEffect of the RDP Content Ingeneral;thehigherpolymertocementratio, thebetterbondstrength. Maximumpolymertocementratioisbetween5%an d10%irrespectivetothepolymertype. , , , , of the RDP Content Thechemistryoftheredispersiblepowderinus ewillaffectonlyshearstressvaluesatearlya geswhensamplesaredrycured. VA/VeoVAbasedRDPsenhancethewetshearstres sofcementitioustileadhesivesduetotheirlo ng -alkylsidechain. , , , ,Effectofformulationparametersonadhesive propertiesofANSI118-15and118-11compliant tileadhesivemortars,InternationalJournal ofAdhesion& Adhesive ,66(2016)73 Mah.

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