Life cycle assessment of recycled coal combustion ash: A case study for building a circular economy in construction aggregates

The massive presence on the entire land surface of coal-fired power plants leaves room only for the imagination of how many tons of coal ash they must dispose of each year. The elimination of these wastes entails a considerable economic expenditure on the involved parts. Above all, not negligible environmental impact for the protection of the planet. The possibility of recycling coal combustion products coming from power plants could be an alternative solution to this problem. At the same time their reusing ensures saving of resources in terms of energy and economy consumption. The feasibility of generating a lower environmental impact by reusing waste material instead of natural resources is the primary goal of this dissertation. To evaluate these impacts, a Life Cycle Assessment (LCA) method is performed. Life cycle of lightweight aggregates manufactured with raw materials supplied by nature or waste is compared in this study. The data collected, following careful research, has been implemented through GaBi software. For a correct comparison, it is assumed that a ton of raw material is processed for both production cycles of the two different products analyzed. The results obtained take into account two transport scenarios for each evaluated aggregate. They show how to produce lightweight aggregates using coal combustion products as raw material instead of natural resources is more convenient. This involves energy savings ranging between 13% and 57% and greenhouse gas emissions reduced from 12% to 58%.