Comparative environmental assessment of low and high CaO fly ash in mass concrete mixtures for enhanced sustainability: Impact of fly ash type and transportation

Christian R Orozco; Somnuk Tangtermsirikul; Takafumi Sugiyama; Sandhya Babel

doi:10.1016/j.envres.2023.116579

Comparative environmental assessment of low and high CaO fly ash in mass concrete mixtures for enhanced sustainability: Impact of fly ash type and transportation

Environ Res. 2023 Oct 1:234:116579. doi: 10.1016/j.envres.2023.116579. Epub 2023 Jul 7.

Authors

Christian R Orozco¹, Somnuk Tangtermsirikul², Takafumi Sugiyama³, Sandhya Babel⁴

Affiliations

¹ Sirindhorn International Institute of Technology, Thammasat University, PO Box 22, Pathum Thani, 12121, Thailand; Graduate School of Engineering, Hokkaido University, Japan, Sapporo, 060-8628, Hokkaido, Japan.
² Sirindhorn International Institute of Technology, Thammasat University, PO Box 22, Pathum Thani, 12121, Thailand.
³ Faculty of Engineering, Hokkaido University, Japan, Sapporo, 060-8628, Hokkaido, Japan.
⁴ Sirindhorn International Institute of Technology, Thammasat University, PO Box 22, Pathum Thani, 12121, Thailand. Electronic address: sandhya@siit.tu.ac.th.

PMID: 37423372
DOI: 10.1016/j.envres.2023.116579

Abstract

The effect of fly ash type on the sustainability of concrete mixtures has yet to be quantified. This study aims to assess the environmental impacts of low calcium oxide (CaO) and high CaO fly ash in mass concrete mixtures from Thailand. The study analyzed 27 concrete mixtures with varying percentages of fly ash as a cement replacement (0%, 25%, and 50%) for 30 MPa, 35 MPa, and 40 MPa compressive strengths at specified design ages of 28 and 56 days. Sources of fly ash have been located between 190 km and 600 km away from batching plants. The environmental impacts were assessed using SimaPro 9.3 software. The global warming potential of concrete is reduced by 22-30.6% and 44-51.4% when fly ash, regardless of type, is used at 25% and 50%, respectively, in comparison with pure cement concrete. High CaO fly ash has more environmental benefits than low CaO fly ash when utilized as a cement substitute. The reduction in environmental burden was most significant for the midpoint categories of mineral resource scarcity (10.2%), global warming potential (8.8%), and water consumption (8.2%) for the 40 MPa, 56-day design with 50% fly ash replacement. The longer design age (56 days) for fly ash concrete showed better environmental performance. However, long-distance transport significantly affects ionizing radiation and ecotoxicity indicators for terrestrial, marine, and freshwater environments. Furthermore, the results show that a high cement replacement level (50%) may not always have a reduced environmental impact on mass concrete when considering long-distance transportation. The critical distance calculated based on ecotoxicity indicators was shorter than those calculated using global warming potential. The results of this study can provide insights for developing policies to increase concrete sustainability using different types of fly ash.

Keywords: Fly ash; High CaO; Life cycle analysis; Low CaO; Mass concrete; Transportation.

Publication types

Research Support, Non-U.S. Gov't

MeSH terms

Calcium Compounds
Coal Ash*
Construction Materials*
Oxides

Substances

Coal Ash
lime
Oxides
Calcium Compounds