Environmental sustainability and life cycle assessment of pilot scale application of coal combustion residue as structural fill in mechanically stabilized earth walls

Abstract

In this study, three types of coal combustion residue (CCR) have been used, and the life cycle impact of CCR as structural fill behind mechanically stabilized earth (MSE) walls of three different heights has been conducted. The analysis has been done using OpenLCA software. Results have been compared with MSE walls using natural sand as a structural fill. It is observed that the environmental impacts of using CCR reduce by more than 50 % compared to those of using natural sand. Amongst CCR, the maximum impact is shown by fly ash and the least by bottom ash. Relative to natural sand, the impacts of using CCR decrease with an increase in wall height. The cost analysis of the walls indicates that if structural fills are transported from the same distance, the cost of construction with natural sand is 18–46 % higher than that by CCR as fill. Results reveal that utilizing CCR as structural fill in MSE walls proves to be a more economic and eco-conscious choice compared to the conventional natural soil. These findings could hold considerable implications for the construction sector and its efforts to minimize ecological footprint.