Properties of mortars made with waste glass as fine aggregate – A South African study

An investigation was conducted on the potential use of waste glass (WG) as fine aggregates in mortars. It is estimated that 7.2 % of the waste stream in South Africa consists of glass. Much of this WG is disposed to landfills. In the present study, mortar mixtures of 3.0 aggregate/cement ratio and water/cement ratio of 0.6 were used. WG was incorporated as partial replacement of granite fine aggregate in proportions of 0, 20, 30, 50 and 70%WG. Mortar cubes of 50 mm size and prisms of size 25 x 25 x 285 mm, were prepared. The tests conducted include density and workability, compressive strength and expansion due to alkali-silica reaction (ASR) as per ASTM C 1260. It was found that workability increased with increase in the proportion of WG incorporated into the mixtures, while density and compressive strength correspondingly decreased. Strength loss not exceeding 11% was obtained for proportions of 20 to 30% WG fine aggregate. Also, 20% WG mixture gave ASR expansion of less than 0.10% at 16 days which satisfies the requirement for non-expansive cementitious systems.