Abstract

Cracks in concrete structures during early ages occur more often than expected. It affects adversely the structure, such as serviceability and durability. The effect of internal concrete volume changes in absence of loads, such as chemical and drying shrinkage plus the effect of temperature changes due to heat of hydration are normally not included during design stages, despite specific recommendations in Codes when those are significantly restrained. This work addressed the development of a simple 1D assessment tool that considers the heat of hydration of cement, the thermal and viscoelastic properties of young concrete and the degree of external restraint. By performing an iterative calculation procedure up to 7 days, the model graphically shows the expected core and surface temperature development, the corresponding stress development and the Cracking Index for different heights of the concrete element. The tool allows simulating parameters, such as mix design, thermal properties including the heat transfer coefficient, placement conditions such temperature during pouring and curing, demolding time, the geometry of the element, and consideration of chemical and drying shrinkage. Its applicability is discussed for a cast-in-place concrete beam where temperature measurements were done, and for a high-cracked wall foundation system of a liquid containing structure.