Synergistic effects of silica nanoparticles/polycarboxylate superplasticizer modified graphene oxide on mechanical behavior and hydration process of cement composites

Abstract

In this paper, the graphene oxide (GO) modified by polycarboxylate superplasticizer (PC) (PC@GO) was decorated by silica nanoparticles (SiO₂ NPs) to form a hybrid structure of SiO₂ NPs/PC@GO. The as-prepared SiO₂ NPs/PC@GO hybrid was incorporated in cement matrix for further reinforcement. The results show that SiO₂ NPs are uniformly distributed on the surface of GO nanosheets. The addition of SiO₂ NPs/PC@GO hybrid (1.5% SiO₂ and 0.02% GO by weight of cement) can increase the compressive strength by factors of 38.31%, 44.47% and 38.89% at 3, 7, 28 days, respectively, which are much higher than those of cement composites reinforced by a single-promoter (either PC@GO or SiO₂ NPs). Moreover, our results demonstrate that SiO₂ NPs/PC@GO hybrid can accelerate the cement hydration, improve the degree of pozzolanic reaction and refine the microstructure of hydration products. The excellent reinforcement is attributed to the synergistic effects of SiO₂ NPs/PC@GO hybrid including better dispersion property, higher degree of pozzolanic reaction and cross-linking structure of [SiO₂–GO–CSH]. This work provides a very effective way to reinforce cement composites by SiO₂ NPs/PC@GO hybrid.