Development of electrically conductive concrete and mortars with hybrid conductive inclusions

Abstract

Electrically Conductive Cementitious Composites (EC3) have been developed in the last decades to solve the drawbacks of conventional de-icing solutions, especially for urban regions with heavy snowfall where the cost of snow removal and accidents have been considerably increasing. This work aims at developing Electrically Conductive Concrete (ECC) and Mortars (ECM) at varying cement-to-water ratios (w/c) and curing conditions by combining electrically conductive inclusions, such as, carbon fibers, steel fibers, graphite powders, copper powder, and graphene. All samples were tested in terms of resistivity and mechanical strength. Moreover, the effect of thermal drying and long-term storage at 100% Relative Humidity (RH) on the electrical resistivity was studied. Among several mix designs with satisfactory electrical resistivity for de-icing applications, it was possible to develop an economically viable ECC mix design with a reduced volume of steel fibers and graphite powder with respect to that employed in previous works. Moreover, an ECC mix design with a quaternary mixture of conductive inclusions including a small amount of graphene exhibited a very low resistivity (177 Ω·cm) with a compressive strength of 24 MPa. For the ECC mix designs with low w/c ratio, the reduced capillary porosity seems to strongly affect the electrolytic ion conduction effect.