Which solution is more sustainable: Waste foundry sand stabilized with alkali-activated binder or Portland cement?

Abstract

This study compares the sustainability of waste foundry sand (WFS) stabilization with two alternative binders: alkali-activated sugarcane bagasse ash-eggshell lime binder (AAB) and Portland cement (PC). Life cycle assessments were conducted to evaluate the environmental and economic implications of two dosages: high-density/low-binder (HDLB) and low-density/high-binder (LDHB). A social life cycle assessment was carried out to investigate the social impacts of WFS stabilization strategies. The MIVES tool was used to measure the sustainability index. The HDLB dosage reulted in lower environmental and economic impacts compared to LDHB, i.e., higher degree of compaction and lower binder content contribute to sustainability. In WFS-AAB, the environmental impacts were mainly associated with NaOH and lime production and materials transportation, while Portland cement production was the most influential factor in WFS-PC. The AAB-HDLB showed higher direct costs and lower social cost of CO2 than PC-HDLB. WFS-AAB generated a higher positive social impact compared to WFS-PC. The social pillar was mainly influenced by the indicators “average wage” and “women employment”. WFS stabilization with AAB-HDLB presented a higher sustainability index (0.59) than PC-HDLB (0.49).