Impermeability and interfacial bonding strength of TiO₂-graphene modified epoxy resin coated OPC concrete

In this study, a novel TiO₂-graphene modified epoxy resin employed as coatings for ordinary Portland cement (OPC) concrete was for the first time fabricated with three different dosages. It was found that the TiO₂-graphene could be dispersed homogeneously in the epoxy resin matrix without reducing interfacial bonding strengths between coatings and OPC concrete substrates. Moreover, with the aid of certain dosages of TiO₂-graphene nanofiller (0.3 % and 0.5 %), both the impermeability towards water and chloride of the OPC concrete reflected by capillary sorptivity and chloride penetration respectively was greatly improved compared to the pure epoxy resin coated concrete or concrete substrate without coatings. In contrast, 1.0 % dosage led to higher water and chloride permeability than the concrete coated by pure epoxy resin coating. Thus, within the range of considered dosages, it seems that 0.5 % dosage achieved the best coating performance evidenced by the lowest capillary sorptivity and chloride permeability, overcoming the disadvantages of 0.3 % (not enough) and 1.0 % (noticeable agglomerations). In addition, TiO₂-graphene addition seems to have no significant impact on the gas permeability of the epoxy resin coated OPC concrete. Overall, the cost-effective fabrication method and improved impermeability of OPC concrete coated by the epoxy resin which is enhanced by the TiO₂-graphene nano-composite create more opportunities for epoxy resin being utilised as surface coatings for cementitious binders.