Chemical shrinkage behavior and prediction model of cement-based composite paste with the addition of graphene oxide

In order to reveal the chemical shrinkage characteristics of graphene oxide cement composite paste (GO/C), the chemical shrinkage of cement composite paste with different water-cement ratio (0.3, 0.4, 0.5) and different mass fractions of graphene oxide (GO) (0wt%, 0.01wt%, 0.02wt%, 0.03wt%, 0.04wt% and 0.05wt%). The results show that the chemical shrinkage of GO/C is significantly increased with an increase in water-cement ratio. At the same water-cement ratio, the early chemical shrinkage of GO/C is lower than that of ordinary cement paste, and when the mass fraction of GO is 0.04wt%, the shrinkage value reaches the minimum. However, the growth rate of chemical shrinkage of GO/C specimens is obviously faster than that of ordinary cement paste in later hydration process. The analysis shows that the influence of GO on the chemical shrinkage of cement paste is mainly attributed to the regulation of GO on the pore structure of cement paste and the bonding behavior of GO with calcium hydroxide crystal. Furthermore, based on the comparison results of existing shrinkage models, it is found that the chemical shrinkage models of ordinary cement cannot accurately predict the chemical shrinkage of GO/C. Therefore, in order to consider the effect of GO, K(\xi , t) function is introduced as an influence parameter on the basis of Wu Lang model, and its specific expression is obtained by curve fitting. Finally, a prediction model suitable for GO/C chemical shrinkage was established.