Effect of carbon black on electrical curing of fresh concrete for cold regions

Abstract

Nowadays, there are many accelerated curing methods which are an important issue for early strengthening of concrete. It was aimed to accelerate the hydration of carbon-black-blended concrete by shortening the molding time, and to achieve concrete casting under cold weather. For this purpose; 0, 1, 2 and 3 percent of carbon black added to the concrete instead of cement by weight and the concrete was produced by electrical curing method. During the curing, 0, 45, 60 and 90 V voltage values were applied on fresh concrete for 24 h. The voltage applications were carried out at different temperatures as under ambient temperature conditions (22 degrees C), and at 0 degrees C and -10 degrees C using an air-conditioning cabinet. After the electrical curing process, the concrete samples were demoulded and cured in the standard curing pool for 7 and 28 days, and then physical and mechanical properties were investigated. It was found that increased carbon black ratio and stress intensity resulted with increase in the internal temperature of the concrete. With an increase in voltage and carbon black ratio, it was found that the duration of the setting was accelerated and the molding time was shortened. With an increase in carbon black ratio, the setting times decreased. In the electrically cured concrete, 30% increase in strength was observed at early days. (C) 2020 Elsevier Ltd. All rights reserved.