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