Prediction of the hydration heat, temperature distribution and thermal stress of mass concrete

Thermal cracks induced by hydration heat are one of the primary factors affecting the durability of mass concrete structures. To accurately predict the early-age temperature rise and thermal stress of mass concrete, a hydration heat prediction model for Portland cement was established based on the Parrot-Killoh hydration kinetic model, considering the effects of water-cement ratio, cement fineness, relative humidity and temperature. Subsequently, taking the predicted hydration heat as the internal heat source, a finite element analysis model for the temperature and thermal stress fields of mass concrete was constructed. The influence laws of key parameters including water-cement ratio, cement fineness and curing temperature on the core temperature and thermal stress were systematically investigated. The results indicate that reducing the water-cement ratio or using finer cement significantly increases the peak core temperature and peak compressive stress of concrete; an increase in curing temperature accelerates the hydration reaction, raises the peak temperature and reduces the late-age tensile stress. Furthermore, a thermo-mechanical-damage coupled model based on the Mazars damage criterion was employed to simulate the early-age damage evolution process, revealing that damage tends to occur on the surface and edge regions within 24 h after casting. The multi-scale prediction method proposed in this study provides a reliable theoretical tool and engineering reference for temperature control and crack prevention design of mass concrete.