Experimental study on the combined effect of temperature and mix parameters on the premature cracking of cement-based materials

Cracking can occur in early-age concrete when thermal, hydrous or physico-chemical deformations are restrained. In addition to a deterioration of the aesthetic aspect, this premature cracking generates a loss of durability of the structure. In this article, the autogenous cracking of cement-based materials is studied using the ring test method. A specific experimental system based on this method was developed. It enables to keep the specimens in autogenous and temperature-controlled conditions during the whole test duration. The influence of both temperatures between 20°C and 40°C and the degree of restraint on the first autogenous cracking age of CEM I cement pastes with water-to-cement ratio W/C = 0.3 and 0.4 has been examined. Increasing the curing temperature and the degree of restraint and decreasing the W/C ratio leads to a shortening of the cracking age. Moreover, the level of maturity (hydration degree) corresponding to the age of the first autogenous cracking decreases when the curing temperature increases.