Utilization of fine concrete waste as a lightweight aggregate via granulation: Technical and environmental assessment
Kalle Kursula, Abhijit Mistri, Mirja Illikainen, Priyadharshini Perumal
Abstract
The reutilization of construction and demolition (C&D) waste alleviates the waste disposal problem and significantly reduces environmental pollution. However, fine concrete waste from various sources, such as, ready-mix plants and precast elements, is often considered a low economic value material and left for landfill. Considering a sustainable environment, material recycling should be increased in place of landfilling. The present study explores the utilization of these fine concrete wastes as aggregate material in construction via different granulation processes. The waste material used for in this study replicates the real practical situation in the construction industry. Different manufactured aggregates were characterized for their intended performance in concrete and then lightweight concrete (LWC) was made. A commercial lightweight aggregate (LWA), LECA was also considered for the characterization and concrete production by itself and combination with manufactured aggregates. Moreover, a life cycle assessment was conducted by following ISO 14040-44 guidelines to evaluate the environmental impacts within the aggregate manufacturing process as well as in concrete production. A cradle-to-gate analysis was conducted to estimate the global warming impact (GWI) and cumulative energy demand (CED) for different manufactured aggregates and finally at the concrete level. It was observed that the manufactured aggregates via the granulation process were suitable for LWC and were comparable with commercial LECA. Although the manufactured aggregates were heavier than LECA, a combination of 50% manufactured aggregate and LECA can be suggested. Moreover, the environmental impact assessment ensures the most effective granulation option for the utilization of fine C&D waste in new concrete. The calculated land conservation from utilizing C&D waste in construction shows additional benefits towards achieving sustainability.