Evolution on fracture properties of concrete during steam curing

This paper investigated the fracture properties of concrete after steam curing ranging from 4 to 48 h at a typical constant temperature of 60 degrees C. The evolution pattern of fracture properties for concrete during steam curing was revealed, and the equivalent maturity was adopted to estimate the development of fracture parameters. The results indicated similar to the mechanical parameters, the initial fracture toughness K-Ic(ini) exhibited an increase-decrease tendency as increasing steam curing hold (SCH) time. However, the unstable fracture toughness K-Ic(un) and fracture energy GF were found to increase monotonously with SCH time, leveling off approximately between 16 h and 48 h. The equivalent maturity approach was proved to be available to evaluate the fracture parameters of steam-cured concrete with a relative error of less than 10%. In addition, the crack extension resistance during whole fracture process was also analyzed, and it was found the SCH time should be kept within 16 hat 60 degrees C for the development rate of fracture properties. The test results can provide a basis for the control of cracks of concrete in steam curing process.