Microstructure and transport properties of cement-based material enhanced by graphene oxide

The microstructure and transport properties of mortars made with graphene oxide (GO) and cement and with similar consistency were experimentally investigated and compared with those of control mortars made using Portland cement. Polycarboxylate superplasticiser was used to improve the consistency of GO-modified mortars and the dispersibility of GO nanosheets. Compared with the control samples, the GO-modified mortars with similar consistency showed a 33·2% reduction in the chloride migration coefficient and a 61·6% reduction in the initial rate of water absorption. These improvements are due to the addition of GO particles in the mortars, which inhibit crack growth, change the morphology of hydrated crystals and refine the pore structure. Very small amounts of GO additives were found to significantly decrease the macropore volume fraction and the critical and average pore diameters. In an attempt to understand the correlation between the pore size distribution and the macroscopic transport performance, both the critical pore diameter and the macropore volume fraction were found to be exponentially dependent on the chloride migration coefficient. The average pore diameter was found to be linearly related to the initial absorption rate of the mortars, but was independent of the secondary absorption rate.