Abstract
Concrete is a major material used in the construction industry that emits a large amount of substances with environmental impacts during its life cycle. Accordingly, technologies for the reduction in and assessment of the environmental impact of concrete from the perspective of a life cycle assessment (LCA) must be developed. At present, the studies on LCA in relation to greenhouse gas emission from concrete are being carried out globally as a countermeasure against climate change. However, the studies on the impact of the substances emitted in the concrete production process on acidification and eutrophication are insufficient. As such, assessing only a single category of environmental impact may cause a misunderstanding about the environmental friendliness of concrete. The substances emitted in the concrete production process have an impact not only on global warming but also on acidification and eutrophication. Acidification and eutrophication are the main causes of air pollution, forest destruction, red tide phenomena, and deterioration of reinforced concrete structures. For this reason, the main substances among those emitted in the concrete production process that have an impact on acidification and eutrophication were deduced. In addition, an LCA technique through which to determine the major emissions from concrete was proposed and a case analysis was carried out. The substances among those emitted in the concrete production process that are related to eutrophication were deduced to be NOx, NH3, NH4+, COD, NO3−, and PO43−. The substances among those emitted in the concrete production process that are related to acidification, were found to be NOx, SO2, H2S, and H2SO4. The materials and energy sources among those input into the concrete production process, which have the biggest impact on acidification and eutrophication, were found to be coarse aggregate and fine aggregate.
Highlights
Concrete is a major construction material that emits a large amount of substances with environmental impacts during its entire life cycle.technologies for the assessment of and reduction in environmental impacts of concrete from the perspective of life cycle assessment (LCA) must be developed
The effects were assessed by concrete strength, mix rate of admixtures and mix rate of recycled aggregate, and the results found the following: As the ground-granulated blast-furnace slag (GGBS) mix rate increased at the mix design of concrete, GWP decreased while acidification potential (AP) and eutrophication potential (EP) remained almost unchanged because the increase or decrease in the mixing amount of cement and GGBS hardly had any influence on AP and EP
As the mix rate of recycled aggregate increased, GWP increased while AP and EP decreased because recycled aggregate is lower than natural aggregate in terms of nitrogen oxide (NOx) emissions
Summary
Concrete is a major construction material that emits a large amount of substances with environmental impacts during its entire life cycle (production process, construction, maintenance, dismantlement, and scrapping). Technologies for the assessment of and reduction in environmental impacts of concrete from the perspective of life cycle assessment (LCA) must be developed. The studies on LCA of greenhouse gas emission from concrete are being carried out globally as a countermeasure against climate change. The studies on the impact of the substances emitted in the concrete production process on acidification and eutrophication are insufficient. The substances emitted into the air and water during concrete production have impacts on global warming, and on acidification and eutrophication [1]. Eutrophication is a phenomenon in which inland waters are heavily loaded with excess nutrients due to chemical fertilizers or discharged wastewater, triggering rapid algal growth and red tides
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