Orozco Christian R, Tangtermsirikul Somnuk, Sugiyama Takafumi, Babel Sandhya
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.
Sirindhorn International Institute of Technology, Thammasat University, PO Box 22, Pathum Thani, 12121, Thailand.
Environ Res. 2023 Oct 1;234:116579. doi: 10.1016/j.envres.2023.116579. Epub 2023 Jul 7.
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.
粉煤灰类型对混凝土混合物可持续性的影响尚未得到量化。本研究旨在评估泰国大体积混凝土混合物中低氧化钙（CaO）和高CaO粉煤灰对环境的影响。该研究分析了27种混凝土混合物，这些混合物在28天和56天的指定设计龄期下，以不同百分比的粉煤灰替代水泥（0%、25%和50%），抗压强度分别为30MPa、35MPa和40MPa。粉煤灰来源位于距搅拌站190公里至600公里之间。使用SimaPro 9.3软件评估环境影响。与纯水泥混凝土相比，当粉煤灰（无论类型如何）分别以25%和50%的比例使用时，混凝土的全球变暖潜能值分别降低了22 - 30.6%和44 - 51.4%。当用作水泥替代品时，高CaO粉煤灰比低CaO粉煤灰具有更多的环境效益。对于40MPa、56天设计且粉煤灰替代量为50%的情况，在矿产资源稀缺（10.2%）、全球变暖潜能值（8.8%）和用水量（8.2%）的中点类别中，环境负担的降低最为显著。粉煤灰混凝土较长的设计龄期（56天）显示出更好的环境性能。然而，长途运输对陆地、海洋和淡水环境的电离辐射和生态毒性指标有显著影响。此外，结果表明，在考虑长途运输时，高水泥替代水平（50%）对大体积混凝土的环境影响可能并不总是降低的。基于生态毒性指标计算的临界距离比使用全球变暖潜能值计算的临界距离短。本研究结果可为制定利用不同类型粉煤灰提高混凝土可持续性的政策提供见解。
