Crack extension resistance of steam-cured concrete under different curing temperature conditions

The influences of curing temperatures on the fracture characteristics for steam-cured concrete were investigated by using three-point bending (TPB) method. The measured load-crack mouth opening displacement (P-CMOD) curves were used to determine the crack extension resistance curves (KR curves) and fracture toughness. The results showed at each curing temperature, the KR curves first increased with crack growth and then approximately remained constant after the fracture process zone (FPZ) was completely developed. The KR curves for the specimens cured at 45 ?C were slightly higher than those at 20 ?C. However, the KR curves became lower and flatter significantly as increasing the curing temperature ranged from 45 to 95 ?C. The fracture toughness also demonstrated an increase-decrease tendency with the increase of curing temperature, which was consistent to the variation of KR curves. The optimum curing temperature was found to be about 45 ?C in terms of the fracture properties for steam-cured concrete. In addition, the KR curves based on different FPZ models and the stability during crack growth were also analyzed.