Performance evaluation of concrete with waste glass after elevated temperatures

Abstract

Recycling waste glass (WG) to produce concrete is a crucial step towards building sustainability. In this paper, a new approach of substituting coarse aggregate (CA) and fine aggregate (FA) with crushed glass (CG) and glass powder (GP) respectively was proposed to investigate the effect of different CG and GP replacement rates on the performance of concrete after high temperature. A total of 10 groups of mix proportions were designed, and the substitution rates of GP and CG varied from 0 to 30 % by volume. The specimens were heated from 20 °C to 600 °C at a rate of 5 °C/min. After reaching target temperature, they were kept for 2 h and naturally cooled to ambient temperature. Subsequently, mixtures were tested to evaluate the apparent changes, weight loss, volume change, ultrasonic pulse velocity (UPV), damage degree, dynamic elasticity modulus, compressive strength and split-tensile strength before and after high temperature. Results show the compressive strength increased by 3 %-6% from 20 °C to 150 °C, then gradually decreased and a strength loss of 30–40 % was observed after 600 °C. Whereas the splitting tensile strength continued to decline as rising temperature, with a 60 %-70 % change in strength loss after 600 °C. Concrete with 10 % GP substitution and 10 %-20 % CG substitution exhibited better performance in this experiment at room temperature and high temperature in terms of mechanical, physical and durability properties compared to others. Besides, as raised temperature, an increase in water absorption and mass loss was observed for all mixtures, while the UPV reduced until it became doubtful. In conclusion, the combined substitution of CG and GP for natural aggregates can improve the performance of concrete after elevated temperature.