전과정평가를 이용한 골재 재료의 환경 특성 평가

Abstract

In this paper, environmental impacts of waste recycled aggregate materials were estimated using life cycles assessment (LCA). Environmental impacts of construction waste recycled aggregate (RA), slag recycled aggregate (SA), and bottom ash recycled aggregate (BA) were estimated and compared with natural aggregate (NA). The production process of RA was most complicated owing to the heterogeneity of the construction waste, and the level of energy consumption was relatively high. The level of heavy metals leached from RA was relatively low due to the washing process and low heavy metal concentration in the construction waste. Comparing with NA, 63.34%, 56.26% and 34.34% of environmental impacts were reduced in abiotic depletion, ozone layer depletion and photochemical oxidation, respectively. The production process of SA was simplest owing to the homogeneity of the slag, and the level of energy consumption was relatively low. The level of heavy metals leached from SA was relatively high because washing process was excluded in the production process and the slag contained high level of heavy metals. Comparing with NA, 70.86% and 70.62% of environmental impacts were reduced in ozone layer depletion and abiotic depletion, respectively. Production process of BA consumed the middle level of energy and discharged the middle level of heavy metals among the three processes. Comparing with NA, 64.79%, 64.50% and 51.80% of environmental impacts were reduced in ozone layer depletion, abiotic depletion and photochemical oxidation, respectively. The results of multi-dimensional decision making model showed that NA was the optimal aggregate materials when freshwater aquatic ecotoxicity, marine aquatic ecotoxicity, terrestrial ecotoxicity and expediency were emphasized. RA was the optimal aggregate materials when prices was emphasized. SA was the optimal aggregate materials when abiotic depletion, eutrophication, global warming, ozone layer depletion and photochemical oxidation were emphasized. BA was the optimal aggregate materials when acidification and human toxicity were emphasized.