Experimental and numerical study on unsaturated water transport properties of graphene oxide reinforced-concrete by the multiscale approach

Durability is an important property that determines the long-term behavior of cement-based materials. In this study, graphene oxide nanoparticles (GONPs) are proposed to prevent the ingress of water in the concrete. GONPs are the product of chemical exfoliation of graphite and contain a range of reactive oxygen functional groups that enable it as a suitable candidate for reaction in cementitious materials through physical functionalization. The multiscale approach is adopted to study the unsaturated transport properties of GONPs-reinforced concrete. At the nanoscale, the most important parameters for unsaturated mass transport analysis of GONPs-reinforced cement paste are determined through the molecular dynamic (MD) simulation. At the microscale, a hydrated cement model is adopted and its permeability characteristics are calculated. At the mesoscale, a three-phase mesoscale model of concrete is presented, which considers particles, cement paste, and the interfacial transition zone (ITZ) as separate constituents to simulate the unsaturated flow under the mixed actions of capillary suction, external hydrostatic pressure, and gravity. The proposed approach is validated by comparing the numerical result with those of the available experimental data taken from this paper to verify the reliability and efficiency of multiscale model for predicting the unsaturated water transport properties. Experimental and numerical results indicate that the incorporation of a very low fraction of GONPs (0.1% by weight of cement) can effectively hinder the ingress of water molecules. It can be concluded that adding GONPs improve the transport properties of concrete which subsequently improves its durability.