Development of Electrically Conductive Cold Weather Cement Concrete

Abstract

Placing fresh cement concrete is not permitted during cold weather under normal conditions due to the risk of frost damage. On the other hand, electrically conductive concrete can be used for deicing/snow-melting applications. This paper presents laboratory investigations to develop electrically conductive cold weather concrete (ECCWC) that can be cast and cured below freezing temperatures and has sufficient electrical conductivity for Joule heating. The concrete has additive-based freeze protection (ABFP) systems that consist of optimized amounts of accelerators and corrosion-inhibiting admixtures. Several mixture proportions were made with 0.5%, 0.75%, and 1.0% carbon fibers by volume of concrete to increase the concrete’s conductivity. ECCWC specimens were mixed, cast, and cured at −5°C. The measured freezing points of fresh concrete mixtures were below −5°C. The compressive strength development of ECCWC cured at −5°C was slow compared with the strength development of conductive concrete cured at 20°C. However, ECCWC could reach 55 MPa at 28 days of age. The temperature of hardened ECCWC increased by 18.5°C within 20 min when subjected to a potential difference of 30 V (alternating current). ABFP implemented in the ECCWC mixtures reduces the risk of frost damage and provides the opportunity to place fresh conductive cold weather concrete at ambient temperatures of −5°C without the need for taking curing precautions. The developed ECCWC introduces a new method for constructing multifunctional concrete structures to be placed and cured in cold regions.