Influence of Recycled Glass Addition on Mortar Properties

This work was aimed at studying the possibility of reusing waste glass from crushed containers as aggregate for preparing mortars. At present, this kind of reuse is still not common due to the risk of alkali–silica reaction (ASR) between alkalis of the cement and silica of the waste glass. This expansive reaction can cause great problems of cracking and, consequently, it can be extremely deleterious for the mortar durability. The influence of both size and colour of recycled glass coming from post-consumer domestic containers on the properties of mortars was studied. The attention was focused on both mechanical behaviour, investigated by means of bending and compression tests, as well as durability, studied by means of accelerated tests for evaluating the tendency to expand under alkaline environment due to ASR. Several mortars were prepared by replacing at different rate the quartz sand with coarse glass cullet of different colours: clear (i.e. uncoloured), green and amber. Then, pulverized clear glass was added to the mortar mixtures, also in the presence of class F fly ash. Results obtained showed that by using both green and amber glass cullet the mortars are stable, as well as by using powder glass, which also showed a significant pozzolanic effect. On the other hand, considerable expansion due to ASR was detected by using clear glass cullet.