Fracture and failure of thermally damaged concrete under tensile loading

Abstract

Concrete is a brittle composite material where the failure mechanism is closely related to the initiation and propagation of cracks. The presence of microcracks and other defects in concrete allows, unlike in the case of an ideal brittle material, the existence of a failure process that includes the branching and bifurcation of the cracks, which gives rise to the appearance of an inelastic behavior and then to a higher energy consumption during failure and an extension of the zone in which fracture takes place. This work studies the failure behavior of damaged concretes in tension and compares the behavior of concrete of different strength levels and component materials when adopting temperature as the damaging tool. Two water/cement ratios, two types of coarse aggregates and the incorporation of natural pozzolans are included as variables. As a way to evaluate the damage produced in the internal structure of concrete, the dynamic modulus of elasticity was measured on each specimen. Measures of strength, deformability, and fracture energy determined over notched prisms are reported. In a complementary way, the results of compression tests (strength, static modulus of elasticity, and Poisson ratio) over cylindrical specimens are included.