Mechanical and thermal behaviour of concrete with waste rubber and glass powder as fine aggregate and cement substitutes

One way of recycling waste materials such as tyres and glass is to use them in concrete. The effects of the simultaneous use of waste rubber particles (RPs) as a partial substitute for fine aggregate and glass powder (GP) as a partial substitute for cement on the workability and mechanical properties of concrete at ambient temperature and after exposure to high temperature (600°C) were investigated in this work. In total, 13 mixes were prepared. Except for the reference mix, all the other mixes contained a combination of RPs replacing fine aggregate at percentages of 5% or 10% by volume and GP replacing cement at percentages of 10%, 15% or 20%. Two different sizes of RPs were investigated (0.15–1 mm and 3–5 mm). Slump tests were carried out on the fresh concretes. Tests for compressive strength and tensile strength before and after thermal exposure, and tests for mass loss after exposure to elevated temperature were also carried out. To obtain an understanding of the behaviour of the waste materials in concrete, scanning electron microscopy and energy-dispersive X-ray spectroscopy were conducted. In terms of compressive and tensile strengths, of all the mixes containing RPs and GP, the best results were for the mix with 5% RPs of 3–5 mm and 10% GP.