An evaluation of the increased expansion of clay aggregates fired at 1300 °C to maximize lightness for non-structural concrete

Abstract

This work presents the production of expanded clay aggregates (EA) by firing at 1300°C (EA/1300), a high temperature for EA production. Therefore, the material was produced in an attempt to maximize lightness. Initially, it was characterized the natural clay and the expanded clay aggregate. The EA/1300 had a density of 0.56kg/dm3 and a strength of 0.13MPa, reaching an expansion of 645%, while the EA/1250, clay aggregate fired at 1250°C and produced for comparison, had a density of 0.85kg/dm3, a strength of 0.80MPa, and an expansion of 415%. Subsequently, it was made a lightweight concrete (LC/1300) evaluating its physical and mechanical properties. The LC/1300 had an average compressive strength of ∼4MPa, and a density of 1.22kg/dm3. The LC/1250 had a density of 1.43kg/dm3 and a compressive strength of ∼10MPa. Despite the strength reduction, it was concluded that EA/1300 can be a viable material for the production of lightweight concrete (LC), particularly as concrete artifacts, non-structural blocks, void filling, and in thermal and acoustic insulation applications. This novel material showed low density, with a reduction of 15% in relation to the LC/1250, maintaining the properties of lightweight concrete with EA – chemical inertness and fireproof – and with a strength higher than commercial lightweight concrete with polymeric aggregates.