Unraveling the environmental and economic impacts of fly ash utilization on mass concrete considering industry practices

In many emerging economies, the impact of fly ash utilization for mass concrete applications considering industry practices is yet to be quantified. This study quantifies the environmental and economic impacts of fly ash utilization in mass concrete, considering different mix design strategies in actual practice. Thirty-one (31) concrete mixtures from batching plants in the Philippines with 28-day strength design of 13.8–69.0 MPa have been analyzed using life cycle assessment (LCA) in SimaPro 9.3. Results show that when cement is replaced by 10, 15, and 20% of fly ash by weight, the global warming potential values are reduced by 8.5–9.4%, 8.5–20.7%, and 2.4–19.2%, respectively. Increased fly ash replacement shows a more beneficial impact on normal to high-strength than low-strength concrete mixtures in all 18 midpoint categories. Contribution analysis shows that aggregates significantly affect land use, while admixture affects marine eutrophication. A comparative LCA with mixtures from Thailand suggests that designing the compressive strength of fly ash concrete at 56 days will significantly improve its sustainability compared to a 28-day design. The economic benefit of using fly ash is greater for high-strength than for low-strength mixtures. This study will contribute to improving the sustainability of mass concrete production and benefit countries with similar practices.