Effects of early-age thermal microcracking on material properties and structural performance of limestone aggregate concrete

Abstract

High temperature or thermal curing is commonly applied to concrete fabrication but raises concerns for potential microcracks caused by temperature changes. This is particularly concerning for concrete using limestone coarse aggregate given the significant mismatch in thermal deformation between the aggregate and the surrounding mortar. This experimental study aimed to compare the effects of early-age thermal curing on limestone and normal concrete and included relevant tests on samples cured with either normal, or high temperature conditions. Alongside concrete specimens for microcrack observation and material property measurement, reinforced concrete beams were prepared to investigate shear behavior. It was concluded that high temperature at an early age could cause adverse impacts on basic properties of limestone concrete. However, the structural behavior was also enhanced, manifested by fracture properties and shear resistance improvements. These improvements were attributed to the microcracks’ influences on macrocracks, and to the improved shear transmission through cracks.