Abstract
Carbon nanotubes (CNTs) have shown promise for improving the mechanical performance of cement composites through crack-bridging and frictional pull-out. The interactive behaviors between CNTs and cement matrix act are crucial in optimizing the reinforcement of CNTs in cement composites. This study investigates the effects of nano-silica (NS) sol-gel on the interactive behaviors of CNTs and the cement matrix through a series of experiments and analyses. UV-visible spectrometer results show that CNTs are well-dispersed in suspension and the addition of NS has a negligible effect on the stability of CNT dispersion. Calorimetry tests and dynamic mechanical analysis demonstrate the nucleation and frictional performance of CNTs in cement matrix, respectively. The paper shows that the physical adsorption of NS on the CNT surface could result in the acceleration of cement hydration. Morphology observation confirms that a denser interface between CNTs and cement hydrates is formed. Finally, the improved interaction between CNTs and cement hydrates leads to a substantial increase in friction between CNTs and the cement matrix under periodic loading. NS may act as an ideal admixture for improving both the interactive behaviors between CNTs and cement matrix and the damping properties of cement composite.
Highlights
Concrete is used as a structural material due to its low cost, wide availability and ideal mechanical properties
The results indicated that the re-agglomeration of Multi-Walled CNT (MWCNT) in high dosages will lead to poor connection between the MWCNTs and cement matrix, which did not exhibit any noticeable increase in material elasticity
Discussions This study investigates the effects of NS on interfacial adhesion between MWCNTs and cement matrix using various methods
Summary
Concrete is used as a structural material due to its low cost, wide availability and ideal mechanical properties. The tendency that CNTs have to agglomerate is still a key issue when they are dispersed in a cement matrix due to their high specific surface area and van der Waals’ force This poor dispersion confines CNTs as reinforcements in the hydrated cement paste. The mechanisms for these dispersion methods could be explained as follows: ultra-sonication releases high levels of energy, which generate microscopic bubbles in suspension, and the bubbles separate individual CNTs from bundles [18]; ball-milling process would charge the surface of CNTs and enable the individual CNTs insert into the composite [19]; using functional groups introduced by surface functionalization and ionic surfactants could form micelles around the CNTs and inhibit its aggregation [20]; the non-ionic surfactants could be absorbed into the surface of CNTs, which contributes to exfoliating individual CNTs from bundles through a steric stabilization effect [14] Aside from these mentioned methods, another optional method is dispersing CNTs in water with non-covalent functionalization surfactant, which has the characteristic of not changing the inherent electrical and mechanical properties of CNTs [15]. FCoNr bTosthfroofmthe0.s0a2m%p(lethseadMdiWng NsaSm, apnleisn)ctroea0s.e08in%th(ethceonMceWn3trastaimonpolefsM) lWedCNtoTas fsrloigmht0.d02e%cre(athsee MinWab2ssoarmbapnleces). tToa0b.l0e8%2 s(thhoewMs Wth3e sinamtenpsleitsy) loefdthtoe cahsalirgahcttedriesctriecapseeaiknaatbtshoerbwaanvcee.leTnagbtlhe o2fs2h5o0wnsmthaenidntietsnscihtyanogfethdeucrihnagrathcteerinisittiicalp4e8akh asttatnhdeiwnga.veItlecnagnthbeofo2b5s0enrvmedantdhaitts tchheaningteednsuirtiyngofthtehienicthiaalr4a8cthersistatincdpinega.kI,t wcahnicbhe ocobmseprvaeredsththaet tchoenicnetnetnrasittiyonofotfhinedcihvairdaucatellryisdtiicsppeeraske,dwMhWichCcNoTmsp, kaerepst tchoencsoisntecnent tarlaotniognwoifthintdhievsidtaunadlliyngddisupreartsieodn wMw0.e0Whi8eg%CnhNttbhoTyefsw,cdkeeomeispgaethgncteto.oonHffscioMeswtmeWenevtnCeatNrld,oTMenscgWrieswaC0istN.eh0d2Tt%shinewbtsihyttahewniadneditingeonghsstadigotuyefracaoetsfimot0in.me0nw8et%.hwHebenoynwttwhbeeevydie.gorhs,taMogfeWcoeCfmNMeTWnstCwdNeitcThrseaiassde0od.0s2ain%gethboyef intenTsihtye arsestiumltes winednitcabtye. that addition of NS can negligibly affect the dispersion and stability of MWCThNeTrseisnulatsquinedouicsatseusthpaetnsaidodni.tiFoonr othf eNMS WcaCnNnTegdliigsipbelrysiaofnfecint tNheS dgieslp, etrhseioonptainmdalstdaobsilaigtye ooff MMWWCCNNTTss iinn athqiusesotuusdysuissp0e.0n2s%ionb.y Fwoerigthhet oMf WceCmNenTt.dAistpaerhsiigohneirnMNWS CgNelT, tchoenotepntitm, iatsl sdtoasbailgiteyoifs MpoWorCaNnTds tihnethNisS ssteuedmysisto0.0h2a%vebsyligwhetignhetgoatfivceemeeffnetc.t AotnathheigdhiesrpMerW sioCnNinT cthoentleonntg, ittesrsmta.bWiliittyhisa phoigohrearndMtWheCNNSTseceomntsetnot,hathvee sdliigsthatnnceegbateitvweeeefnfecdtiospnetrhseeddisinpderivsiiodnuainl tMheWloCnNgTtesrmm.igWhitthdaimhiingihsehr, MwhWicChNmT acyonlteeandt, tthoeadissttraonncgeebretVwaenenddelispWerasaelds’ infodricveidaunadl MhWenCceNTtos meaigsihetr driem-aingigslho,mwehraicthiomn aoyf lMeaWd CtoNaTsst.ronger Van del Waals’ force and to easier re-agglomeration of MWCNTs
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