Research on the fracture properties with interlayer of low-heat cement concrete under different pouring conditions

This study investigates the fracture performance of low-heat cement concrete containing interlayers under various pouring conditions. Four distinct pouring conditions were established: interval times (1 h, 3 h, 5 h, 7 h), ambient wind speeds (0 m/s, 2 m/s, 6 m/s, 10 m/s), ambient temperatures (10℃, 20℃, 30℃, 50℃), and relative humidity levels (30 %, 50 %, 70 %, 95 %). The analysis focuses on the deformation characteristics of fracture failure, double-K fracture toughness, and variations in fracture energy of the layered concrete. Results show that the horizontal peak load of the P H -CMOD curve, the initial fracture toughness, the unstable fracture toughness, and the fracture energy all have a negative correlation with the aforementioned four pouring conditions. The pouring interval time has the most significant impact.The reason is that the hydration degree and rate of the first layer of concrete are influenced by external pouring conditions, leading to alterations in its hardness and surface structure, ultimately resulting in a weakened bond between the aggregates and mortar at the surface layer. Furthermore, the results of the grey relational analysis reveal the sensitivity of interfacial fracture characteristics to the three environmental factors: relative humidity has the greatest influence, followed by ambient temperature, while environmental wind speed has the least impact.