Effect of graphene oxide on strength and interfacial transition zone of recycled aggregate concrete

Abstract

Abstract This paper studies the effect of graphene oxide (GO) on the strength and interface transition zone of recycled aggregate concrete (RAC). The results show that the addition of GO enhances the RAC strength, and the compressive strength of the sample containing GO is improved by 7% ∼20.6% at 28 days, compared with the reference group. Meanwhile, with the addition of GO, the total porosity and the number of harmful pores (> 100 nm) of RAC samples decreased by 8.1% ∼35.7% and 3% ∼39.1%, respectively. It is observed from the nano scale characteristics that the addition of GO can significantly reduce pore phase and unhydrated phase content in the matrix, and increase the volume fraction of C–S–H phase, especially the high-density C–S–H phase. In addition, the width of the interface transition zone between old mortar and new mortar containing GO sample is relatively reduced by 25%, but there is no obvious change in the interface transition zone of old aggregate mortar. The strengthening effect of GO on RAC strength is due to the nucleation of GO and the filling effect of micro-aggregate, improving the pore structure and interface transition zone of RAC.