Preparation of Sustainable Concrete with Reduced Carbon Foot Print Using Recycled Aggregate, Fly Ash and Crumb Rubber

Abstract

Concrete plays a vital role in construction, and is the second most used synthetic substance in the world. The enormous development of constructional activities lead to the generation of demolished and construction waste and it is one of the major components of waste generation. These generated materials are dumped on the land affecting the fertility of the soil. For the production of concrete 70% to 75% of aggregates are required. Out of this, coarse aggregate comprises 60% to 67%. From an environmental point of view, production of one cubic meter of natural aggregate concrete (NCA) emits between 323 and 332 kgCO2e. To reduce these carbon emissions, recycled aggregate (RA) from generated demolished structural waste is used as alternative aggregate to produce the recycled aggregate concrete (RCA), fly ash and crumb rubber act as binding materials and replacement for the cement to enhance recycled aggregate concrete (RAC) performance. Properties such as compressive strength, splitting tensile strength of recycled aggregate concrete (RAC) are studied and compared to natural aggregate concrete (NAC), for four different levels 10%, 20%, 30%, and 40% of recycled aggregate (RA) at 7 days and 28 days of curing. Recycled aggregate concrete (RAC) has optimum mechanical properties at 30% recycled aggregate (RA) replacement and is suitable for load-bearing structures. Recycled aggregate concrete (RAC) with 40% replacement showed a decrease in optimum strength but enough to be used for non-load-bearing structures. Use of recycled aggregate (RA) and cementitious materials fly ash and crumb rubber in preparation of concrete can save 1.19 GT CO2e annually for India, allowing a gain of 11,52,320 carbon credits each year.