The potential of industrial waste: using foundry sand with fly ash and electric arc furnace slag for geopolymer brick production

Suchanya Apithanyasai; Nuta Supakata; Seksan Papong

doi:10.1016/j.heliyon.2020.e03697

The potential of industrial waste: using foundry sand with fly ash and electric arc furnace slag for geopolymer brick production

Heliyon. 2020 Mar 31;6(3):e03697. doi: 10.1016/j.heliyon.2020.e03697. eCollection 2020 Mar.

Authors

Suchanya Apithanyasai¹, Nuta Supakata^{2

3

4}, Seksan Papong⁵

Affiliations

¹ International Program in Hazardous Substance and Environmental Management, Graduate School, Chulalongkorn University, Bangkok, Thailand.
² Department of Environmental Science, Faculty of Science, Chulalongkorn University, Bangkok, Thailand.
³ Research Program: Municipal Solid Waste and Hazardous Waste Management, Center of Excellence on Hazardous Substance Management, Thailand.
⁴ Waste Utilization and Ecological Risk Assessment Research Group, The Ratchadaphiseksomphot Endowment Fund, Chulalongkorn University, Thailand.
⁵ Department of Life Cycle Assessment Laboratory, National Metal and Materials Technology Center, MTEC, Bangkok 12120, Thailand.

Abstract

The purpose of this study was to investigate the best ratio of waste foundry sand (WFS), fly ash (FA), and electric arc furnace slag (EAF slag) for the production of geopolymer bricks. In this research study, WFS, FA, and EAF slag were mixed at the ratio of 70:30:0, 60:30:10, 50:30:20, and 40:30:30 with 8M sodium hydroxide (NaOH) and 98% purity sodium silicate (Na₂SiO₃) with a ratio of Na₂SiO₃/8M NaOH = 2.5. The mixtures were compacted in 5 cm × 5 cm x 5 cm molds and cured at an ambient temperature for 28 days. Then, their compressive strength was analyzed. The results showed that the geopolymer bricks with the highest compressive strength were those mixed at the 40:30:30 ratio, with a compressive strength of 25.76 MPa. The strongest bricks were also analyzed using the leaching test to ensure the production involved non-hazardous materials. To compare the environmental impacts of geopolymer bricks and concrete bricks, their effects on climate change, ozone depletion, terrestrial acidification, human toxicity, terrestrial ecotoxicity, and fossil fuel depletion were examined from cradle to grave using SimaPro 8.0.5.13 software. The results of the life cycle assessment (LCA) from cradle to grave showed that the environmental impact of geopolymer brick production was lower in every aspect than that of concrete production. Therefore, geopolymer brick production can reduce environmental impact and can be a value-added use for industrial waste.

Keywords: Civil engineering; Economic feasibility; Electric arc furnace slag; Environmental impact assessment; Environmental management; Environmental science; Fly ash; Geopolymer brick; Leaching of heavy metals; Life cycle assessment; Materials science; Waste foundry sand.