Sustainable structural lightweight concrete utilizing high-volume fly ash cenosphere

Abstract

This paper explores the most feasible technique for producing sustainable structural lightweight concrete (LWC) utilizing high-volume of fly ash cenosphere (FAC), a noble lightweight fine material, as replacement of natural fine aggregate (NFA) with addition of silica fume (SF) as replacement of ordinary Portland cement (OPC). Concrete mixes are designed for different combinations of FAC (60%, 80% and 100%), SF (10%, 15% and 20%) and water-binder (W/B) ratio (0.40, 044 and 0.48) and their mechanical and physical properties are evaluated. Experimental results depict that appropriate dose of SF improves the properties of high-volume FAC based concrete and thus helps in the production of structural LWC satisfying strength and density criteria of ACI 213R-14 (2014). The combinations of 15% SF with 80% FAC at 0.44 and 0.40 W/B ratios result in the properties closer to or even better than the normal concrete. Moreover, the environmental impacts of the concrete mixes comprised of high-volume FAC with addition of SF at different W/B ratio reduce in the range 5.37%-18.86% with respect to the normal concrete. Hence, the structural LWC mixes become sustainable, as they are advantageous from both environmental and social considerations.