Development of electrically conductive concrete

Abstract

The effects of the addition of steel fiber and graphite powder on the electric conductivity of concrete were investigated. The percolation transition zone of the concrete + steel fiber was determined, thus fixing the optimum content of steel fiber at 8.5%. Graphite was added to investigate its influence on the electrical conductivity and mechanical properties of the concrete. The electric current passing through the specimens was measured, setting the electric voltage to 50 V. The surface temperature of the specimens submitted to the electrical current was measured for 20 min. It was observed that the higher the graphite addition, the higher the conductivity was and, therefore, the higher the final temperature, which achieved 58 °C higher than the reference mixture, but the compressive strength decreased from 60 to 30 MPa, although still considered as structural concrete.

Influence of Sulphate Attack on Properties of Modified Cement Composites

“…The crystalline hydration products permeating the cement gel contain water molecules in a chemically bound form. During the independent synthesis of crystal hydration products and their subsequent study [23], it was found that the nature of the electrical conductivity of these new formations is similar to the nature of the electrical conductivity of clinker minerals. In the works of many authors, it has been stated that the specific electrical resistances of the crystal hydration products of the concrete are in the range from 10 6 to 9 × 10 9 Ω/cm.…”

“…However, studies of the corrosion resistance of cement composites with electrical properties are insufficient. Analysis and evaluation of changes in the electrical resistivity under the influence of a complex of external factors [22] is a priority in research, and considers promising practical applications of the modified cement-based composites, such as resistive self-heating of road surfaces [23], grounding, elimination of static electricity, and lightning protection [24,25].…”

“…This solution, unlike, for example, magnesium sulphate [30], allows the ettringite-thaumasite system to be fully synthesized due to the absorption of SO 4 2-ions by samples from a Na 2 SO 4 solution. This process intensifies the crystallization of salt in a moist environment, and leads to the salt crystallization in samples and the further formation of cracks [23].…”

“…Studies of the mechanism of electrical conductivity of the solid phase of composite based on Portland cement show that the hydrated concrete is a combination of hydration products with non-hydrated clinker minerals [1,23], with thermodynamically unstable compounds having imperfectly ordered crystal structures. It is shown [31] that the total calculated change of the entropy in the reactions of the formation of calcium silicates, aluminates, and aluminoferrites is significantly less than the entropy of the clinker materials themselves.…”

“…As a result, the combined action of thermal motion and the electric field can lead to the creation of certain conditions under which a particular ion can become a current carrier. Thus, the electrical conductivity of clinker minerals can be attributed to the ionic type that is characterized by a strong dependence of the electrical conductivity of concrete on the order of ions in its structure [23].…”