Comparative environmental life cycle assessment of artificial fly ash aggregates and natural aggregate production in India

A novel process for the production of angular-shaped high strength fly ash aggregates from an energetic, and environmental perspective is presented in this paper and compared with the production of natural aggregates. This study is significant because there is an increasing demand for aggregates and no published research addressing the environmental impact assessment of fly ash aggregate manufacturing. For the fly ash aggregate production, all technical, energetic, and financial aspects of the production process were evaluated at the pilot-scale production plant. Whereas, for the natural aggregate production process, site-specific data is used. The environmental impacts of aggregate production processes were assessed using SimaPro and the impact analysis methodology IMPACT 2002 + from the “cradle to gate.” The results demonstrate that the production of fly ash aggregates is more desirable than natural aggregates for all environmental impact categories. Using fly ash for aggregate production avoids the impacts due to inert landfilling and extraction of basalt. The findings show that diesel and electricity are the primary sources of energy used to produce aggregates and they are principally answerable for the detrimental effects on respiratory inorganics, global warming, and non-renewable energy. A sensitivity analysis recommends that fly ash aggregate is preferable for all impact categories if the distance between the lime source and the production plant is less than 350 km. The comprehensive life cycle inventory and impact analysis aid in the decision-making process for further improvement in the production procedure of fly ash aggregates and similar life cycle assessment studies.