A Study on the Potential Use of Red Clay and Fly Ash in the Production of Lightweight Expanded Clay Aggregates for Concrete

Abstract

Lightweight expanded clay aggregate (LWECA) has great potential for structural applications due to its high specific compressive strength. It is synthetically produced via the thermal treatment of pellets made from raw material and bloating agent at temperatures ranging from 1,100°C to 1,300°C. In this study, aggregates are produced from red clay, fly ash, and silica sand in various proportions with various bloating agents such as coal, calcium carbonate, and bentonite. The process to produce LWECA has been optimized by varying its composition and sintering temperature. Results show that the optimum conditions for producing pellets of LWECA were achieved using red clay, fly ash, silica sand, and 20 wt% coal as bloating agents and sintering them at 1,270°C for 8 h. Concrete blocks were then made from LWECA (optimized conditions), pumice stone, and traditional coarse aggregates. Results show that the concrete blocks made from LWECA had a low water absorption coefficient, low density, and intermediate compressive strength.