Utilization of Fly Ash Cenosphere for Production of Sustainable Lightweight Concrete

Abstract

This investigation is intended to develop lightweight concrete by replacing the natural fine aggregate (NFA) with an industrial waste called fly ash cenosphere (FAC). For achieving this target, eleven concrete mixes were prepared which include one control mix and another ten mixes prepared in two phases by replacing 20%, 40%, 60%, 80% and 100% of NFA with FAC. In the first phase, additional water required for saturating the FAC was added to the concrete mix to maintain a constant slump (80 ± 5 mm), but in the second phase of investigation, super-plasticizer was used to maintain the same slump. The properties of concrete, such as workability, fresh density, hardened density, compressive, flexural and split tensile strength, rebound number, water absorption and volume of permeable voids were studied. From the above study, it is found that the density of concrete decreases with the increase in FAC content and satisfies the requirement of lightweight concrete if 100% NFA is replaced by FAC. On the other hand, the strength of concrete decreases with the increase in FAC content of concrete. However, the addition of super-plasticizer showed a remarkable enhancement in the hardened properties of concrete for all the mixes, but at the cost of the marginal increase in density of concrete. The mix with 80% FAC and super-plasticizer is found to be optimum one, which can be considered as the sustainable lightweight structural concrete of M25 grade, i.e. the desired grade, utilizing high volume of wastes (FAC) and preserving equal amount of natural resources (NFA).