Sustainable high volume fly ash concrete with recycled C&D waste and dredged marine sand

Abstract

Cement is a basic building material, and second largest building material used on earth. Huge production and use of cement has led to more CO2 being released into the atmosphere, worsening global warming and negatively affecting the environment. As a result, adopting a more sustainable strategy and carefully examining the current admixtures used to replace traditional concrete has become essential. In order to achieve the use of sustainable materials in construction, numerous studies have been done on replacing the cement with a maximum (50%) percentage of Fly Ash which has equivalent strength and better durability than traditional concrete. Very little literature has been reported on developing sustainable concrete mixers by replacing the course and fine aggregates using industrial waste materials. In this study, the M25 mixture design of High Volume Fly Ash (HVFA) Concrete is carried out with an optimum amount of Fly ash (50%) as cementitious material with OPC (50%). This mix percentage of the cementitious element is obtained after various trials and errors with 40, 50, and 60 percent of fly ash. Due to the pozzolanic characteristics of the fly ash and the lower w/cm ratios, the HVFA mixes achieved comparable greater long-term compressive strengths. In present investigation, coarse aggregate was replaced with recycled C&D waste (RCA) and fine aggregate with dredged marine sand (DMS) at its optimum percentage of 25% and 10%, respectively, to get the compressive strength of 30 MPa. This optimum percentage of Recycled C&D waste and dredged marine sand was obtained after conducting various trials and errors with each material, respectively. Evaluation of compressive strength test and flexural strength test determines the mechanical properties of HVFA concrete with RCA and DMS aggregate as replacement of coarse and fine aggregates.