Compressive strength of a concrete mix for pavement blocks incorporating industrial by-product

Abstract

Concrete block paving for roads has been proposed as part of a concept on sustainable infrastructure. In an effort to respond to sustainability and environmental awareness, the use of industrial by-products has been employed in the mix design of the concrete for a block paving system. This contributes towards preservation of natural resources as waste materials from industrial processes are used. Class F fly ash obtained from a coal power station in Vereeniging in South Africa was used for the study. Compressive strength tests were done on concrete cubes containing varying fly ash contents from 0% to 90% as replacement for cement by mass. A decrease in compressive strength and increase in workability was observed with increasing fly ash content. A decrease in water requirement while still producing a workable mix compared to the conventional concrete was also observed with an increase in fly ash content. This would also contribute to the ecological footprint by decreasing the water demand for mixing. The optimal mix from the initial laboratory experiments contained 50% fly ash and exhibited a compressive strength of 37.3 MPa at 28 days.