Abstract
The negative environmental impacts associated with the usage of Portland cement (PC) in concrete induced intensive research into finding sustainable alternative concrete mixes to obtain “green concrete”. Since the principal aim of developing such mixes is to reduce the environmental impact, it is imperative to conduct a comprehensive life cycle assessment (LCA). This paper examines three different types of sustainable concrete mixes, viz., alkali-activated concrete (AAC) with natural coarse aggregates, AAC with recycled coarse aggregates (RCA), and bacterial concrete (BC). A detailed environmental impact assessment of AAC with natural coarse aggregates, AAC with RCA, and BC is performed through a cradle-to-gate LCA using openLCA v.1.10.3 and compared versus PC concrete (PCC) of equivalent strength. The results show that transportation and sodium silicate in AAC mixes and PC in BC mixes contribute the most to the environmental impact. The global warming potential (GWP) of PCC is 1.4–2 times higher than other mixes. Bacterial concrete without nutrients had the lowest environmental impact of all the evaluated mixes on all damage categories, both at the midpoint (except GWP) and endpoint assessment levels. AAC and BC mixes are more expensive than PCC by 98.8–159.1% and 21.8–54.3%, respectively.
Highlights
To mitigate the worst health impacts of climate change, global annual greenhouse gas (GHG) emissions must be halved by 2030 and attain net-zero by 2050 [1] or incur the marginal expense of negative emissions
The International Energy Agency (IEA) estimates that to achieve net-zero emissions by 2050, the direct and indirect CO2 emissions from the building sector should decline by 50% and 60%, respectively, by 2030 [3]
The present study aims to evaluate the environmental and economic impact of untreated building-derived materials (BDM) used as coarse aggregates in activated concrete (AAC)
Summary
To mitigate the worst health impacts of climate change, global annual greenhouse gas (GHG) emissions must be halved by 2030 and attain net-zero by 2050 [1] or incur the marginal expense of negative emissions. This expense could be in the range of USD. The global energy-associated CO2 emissions from the building sector alone accounted for 38% of the total emissions in 2019 [3]. The International Energy Agency (IEA) estimates that to achieve net-zero emissions by 2050, the direct and indirect CO2 emissions from the building sector should decline by 50% and 60%, respectively, by 2030 [3]. Carbon extraction, and the use of alternative materials are some of the strategies for reducing CO2 pollution associated with the use of PC, which were lately introduced [6]
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