Stress-strain behaviour of cement mortars containing recycled glass during and after exposure to elevated temperatures

The present communication investigates the stress-strain behaviour of a self-compacting mortar (SCM) prepared with RG (SCM-Glass) during exposure to elevated temperatures. Unlike a reference SCM prepared with 100% sand (SCM-Sand), which behaved similarly when tested during and after exposure to the elevated temperatures, the SCM-Glass samples suffered up to 83% and 67% decrease of the ultimate strength with a significant gain in the strain capacity during exposure to 600 °C and 800 °C, respectively. This was due to the melting and softening of RG which led to a dramatic deformation of the whole mortar matrix under the dead load. Interestingly, when tested after cooling to room temperature the SCM-Glass samples displayed higher elastic moduli but lower compressive strength than the SCM-Sand samples, indicating the melting and re-solidification of RG induced micro-crack filling effects and the accompanying ITZ improvement had a more beneficial effect on the elastic modulus than on the compressive strength.