Curing parameters development and long-term performance of ohmic heating cured conductive cementitious composites: A comparative study on fiber fraction

Abstract

Ohmic heating (OH) curing is a new method for concrete production in cold areas, while the changing regularity for the curing parameters including electric voltage, current, resistivity and curing temperature during the curing process, and the long-term performance evolution law are still unrevealed. In this research, this method was used to fabricate carbon fibers (CFs) reinforced conductive cementitious composites under −20 °C, the early-age curing parameter and the long-term performance evolution law of the specimen were clarified. Higher CFs dosage showed benefits on the electrical conductivity and heating performance of OH pre-cured specimens. To be specific, simulation and experimental results evidenced that the electrical conductivity of fresh mixture was much improved with 0.6 vol% CFs with the electrical resistivity decremental ratio of 74.82 %. Also, the curing temperature was enlarged in the presence of 0.75 vol% CFs with the incremental ratio around 50 %, indicating the much-improved heating efficiency. Strength test results showed that 1-day OH pre-cured specimens possessed the comparable 150-day strength with RT prepared specimens. Moreover, the hydration products and pore structure test results further verified the feasibility of OH curing with high hydration forming ability and denser microstructure at longer duration. In addition, the “RER” was introduced to evaluate the variation law of electrical resistivity in further curing process, and the corresponding prediction equation was derived.