Quantitative evaluation of crack resistance mechanism of blast furnace slag blended cement concrete via restrained shrinkage stress analysis

Abstract

Application of blast-furnace slag blended cement is an important option to reduce carbon dioxide emission peculiar to concrete materials in construction, and concrete structures using the blended cement concrete (hereafter denoted as BFS concrete) is in great demand. However, shrinkage cracking resistance of BFS concrete decreases at high temperatures. In this study, mechanisms of the reduction of cracking resistance at high temperatures were investigated aiming at the control of shrinkage cracking of BFS concrete as the final goal. Constitutive material properties necessary for restrained shrinkage stress analysis were derived through experiments including such as restrained cracking test under a temperature of 30, 20 and 10°C, free shrinkage test, and compressive creep test. On the basis of the constitutive material properties obtained with the above tests, applicability of existing restrained shrinkage stress analysis to BSF concrete was examined. Analytical results indicate that the stress analysis was found to reproduce the cracking behavior at an ambient temperature from 10 to 20°C. However, at an ambient temperature of 30°C, the analysis overestimates restrained shrinkage stress, which is considered due to underestimating creep effects. This underestimation may occur due to surface micro-cracks eminently generated on surface.