Physico-mechanical characterization of high-volume fly ash cement paste composites

Abstract

The current annual worldwide production of coal ash is estimated at one billion tons of which at least 70-75 % is fly ash. A huge amount of such wastes can seriously damage the environment and ecology of the planet. In this study, a high volume of fly ash was used to produce environmentally friendly building products. The composites were designed as pure cement, and as a result, no aggregates were used. Composites are classified as non-load- bearing elements in the construction sector. Physico-mechanical characterisation of laboratory- produced composites was evaluated based on dry density, water absorption, apparent specific gravity, porosity, and compressive and flexural strength tests. Based on the test results, fly ash can be used as an alternative binder for building products. Water absorption test results of composites produced by 40% fly ash showed satisfactory results. Dry density measurements proved the lightweight nature of the composites. Compressive and flexural strength test results were within the limit specified by the international authorities in the building sector. The composites comprising 60% fly ash attained 30 Mpa compressive strength at 28 days. The produced samples can be used effectively for various civil engineering works. The utilisation of fly ash in construction could reduce the carbon dioxide emission and produce a better sustainable solution.