RECYCLED AGGREGATE CONCRETE (RAC): A viable solution for sustainable construction

Abstract

Construction activities are booming in and around the cities with development and modernization. As a result of these constructions, natural aggregates are being extracted. Simultaneously, there is a significant amount of construction and demolition waste (CDW) generated due to the demolition of structures either due to the structure attaining service life or fashion and the ongoing trend of reconstruction. Therefore, recycling coarse aggregate from CDW in concrete is one of the sustainable solutions to prevent a serious threat to the environment due to the extraction of virgin aggregates and landfilling. This paper presents the results of a study undertaken to examine the influence of recycled concrete aggregate on the properties of new concrete and its life cycle cost (LCC) analysis. It is clear from the test that the strength of RAC is much lowered than natural aggregate concrete (NAC). In order to achieve the optimum strength, the natural aggregate is replaced by recycled aggregate within a range of 0% to 100%, in intervals of 10%. Additionally, to enhance its strength further, reinforcing RAC with new and recycled polypropylene (PP) fiber is done in percentages ranging from 0.25% to 2% by weight of cement with an interval of 0.25%. For analysis, compression, and split tensile strength tests were performed at the end of 28 days of the curing period. The result revealed that 40% replacement of natural aggregate with recycled aggregate achieves the ideal percentage replacement without compromising the strength. Moreover, incorporating 1.5% of new PP fiber or 1.25% of recycled PP fiber in the RAC provides optimum strength. For LCC analysis, the initial investment cost, operations, and maintenance cost, and salvage cost of all the alternatives are compared. Through this analysis, it was determined that the LCC of concrete manufactured using recycled aggregate as concrete ingredients is the lowest. Consequently, incorporating recycled aggregates in concrete production reduces the LCC compared to using natural aggregates.