Cohesive Fracturing and Stresses Caused by Hydration Heat in Massive Concrete Wall

Avoidance of cracking damage due to hydration is an important objective in the design of nuclear reactor containments. Assessment of the safety against cracking requires a realistic material model and its effective numerical implementation. Toward this goal, the paper develops a comprehensive material model which includes approximate simulation of cracking based on the principles of cohesive fracture mechanics, as well as an up-to-date creep formulation with aging and temperature effects. A standard heat conduction model is incorporated in the analysis as well. Since the crack width is the most important characteristic of cracking damage, particular attention is paid to crack spacing which governs crack width. The results of stability analysis of parallel crack systems based on fracture mechanics are used to estimate the spacing of open cracks as a function of their depth. Numerical simulations clarifying various aspects of hydration heat effects are presented.