Abstract
Worldwide cement production is around 4.2 billion tons, and the fabrication of one ton of ordinary Portland cement emits around 900 kg of CO2. Blast furnace slag (BFS) is a byproduct used to produce alkali-activated materials (AAM). BFS production was estimated at about 350 million tons in 2018, and the BFS reuse rate in construction materials of developing countries is low. AAM can reduce CO2 emissions in relation to Portland cement materials: Its use in construction would be a golden opportunity for developing countries in forthcoming decades. The present research aims to formulate AAM destined for future applications in developing countries. Two activators were used: NaOH, Na2CO3, and a mixture of both. The results showed that compressive strengths within the 42–56 MPa range after 28 curing days were obtained for the Na2CO3-activated mortars. The characterization analysis confirmed the presence of hydrotalcite, carbonated phases, CSH and CASH. The economic study showed that Na2CO3 was the cheapest activator in terms of the relative cost per ton and MPa of manufactured mortars. Finally, the environmental benefits of mortars based on this reagent were evidenced, and, in terms of kgCO2 emissions per ton and MPa, the mortars with Na2CO3 yielded 50% lower values than with NaOH.
Highlights
Worldwide cement production in 2019 was 4.2 billion metric tons, while China alone produced2.2 billion metric tons and India 320 million metric tons
Overall cement production is estimated to increase from 3.27 billion metric tons in 2010 to 4.83 billion metric tons by 2030 [1]
Cement production is responsible for about 8% of the anthropogenic CO2 emissions [2]
Summary
Worldwide cement production in 2019 was 4.2 billion metric tons, while China alone produced. 2.2 billion metric tons and India 320 million metric tons. Overall cement production is estimated to increase from 3.27 billion metric tons in 2010 to 4.83 billion metric tons by 2030 [1]. Cement production is responsible for about 8% of the anthropogenic CO2 emissions [2]. The Intergovernmental Panel on Climate Change (IPCC) proposes that global anthropogenic CO2 emissions need to lower by 45% from 2010 by 2030 to limit global warming to 1.5 ◦ C [3]. The use of alkali-activated materials (AAM) can reduce CO2 emissions up to 80% compared to Portland cements materials by using blast furnace slag (BFS) or fly ash (FA), among other precursors [4]. In 2018, the steel industry’s worldwide slag production was around 600 million tons, of which
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