Residual compressive response of concrete produced with both coarse and fine recycled concrete aggregates after thermal exposure

This paper presents an experimental work on the compressive behaviours of concrete using both coarse and fine recycled concrete aggregates (CRCA and FRCA) after heating to temperatures of 20–800 °C. Three concrete mixtures were prepared with 100% CRCA and varying replacement levels (0, 50% and 100%) of FRCA. Prismatic specimens (100 × 100 × 300 mm) were subjected to the target temperatures for 180 min, and then were compressed after cooling to room temperature. The failure patterns, whole stress-strain curves, compressive strengths, moduli of elasticity (stiffness) and peak strains of concretes after thermal exposure were obtained from the experiments. The effects of temperature and FRCA content on the residual compressive response were evaluated. Additionally, microstructural characterization was analyzed to illustrate the thermal damage to concrete. Results obtained show that the elevated temperature has a negative influence on the compressive properties of RAC. Concrete incorporating 50% FRCA presents a better thermal performance as compared to the concrete without using FRCA. Finally, a compressive stress-strain model for RAC after thermal exposure was suggested on the basis of the experimental results.