ABSTRACT
Drying shrinkage and heat of hydration are main causes of the crack of concrete structure.
A series of researches to reduce the thermal cracks of the concrete due to the heat of hydration by adding urea to massive concrete has already been published (Ayano et al., 1995, Sakata & Ayano 1996, Sakata & Ayano 1998, Mwaluwinga et al., 1997). Urea, when mixed into concrete, lowers the temperature of fresh concrete by the endothermic reaction, a chemical reaction that absorbs energy. In addition, urea retards the setting times of concrete by delaying the hydration process. As a result, temperature rise of massive concrete can be reduced by the addition of urea into concrete.
