Electric curing parameters of mortar and its mechanical properties in cold weather

Thermal curing is an effective way to accelerate the curing of cementitious materials and can be used for concreting in cold weather, in order to prevent frost damage. This study investigates electric-thermal process curing of mortar at 20 °C and −10 °C. Fresh mortar specimens were subjected to different electric potential differences and their internal and top surface temperatures were monitored using a thermocouple and a thermal camera, respectively. A theory for predicting the temperature increase of the mortar based on the applied electric parameters was developed. Furthermore, the system was used to maintain the internal temperature of mortar specimens at 10 °C for 12 h while these were exposed to −10 °C inside a cold room. Compressive and flexural strength results show that electric curing can prevent frost damage. For example, 28 days compressive strength of normally cured mortar specimens exposed to −10 °C was 27.2 MPa while mortar specimens subjected to electric curing achieved a compressive strength of 51 MPa. Results from mercury intrusion porosimetry tests showed an increase in porosity for normally cured specimens, which was responsible for strength loss.