Lightweight aggregate based on waste glass and its alkali-silica reactivity

The possible use of waste glass for the production of lightweight aggregate has been studied. The aggregate, in the form of highly porous granules, was produced by mixing together finely ground waste glass and an expansive agent and firing this mixture at a selected temperature. The expansive agent was chosen on the basis of the results of DTA/TGA experiments, which were carried out on some selected agents and confirmed by using a hot-stage microscope, where the temperature interval of the expansion was also determined. Pilot production of about 0.5 m³ of the aggregate was performed in a rotary kiln, and the water absorption and bulk density of the aggregate so obtained were determined. Special emphasis was placed on the determination of the alkali-silica reactivity of the aggregate, and the results of initial tests for alkali-aggregate reaction were encouraging, given the high potential reactivity of the material. However, before such aggregate can be considered safe for general use in concrete, longer-term concrete prism tests need to be carried out, which would cover the range of mixes in which the aggregate is likely to be used.