Evaluating engineering properties and environmental impact of pervious concrete with fly ash and slag

摘要

This study evaluated engineering properties, cost, and energy and environmental impacts of three pervious concrete mixtures: pervious concrete with regular Portland cement (PC-Regular); with fly ash (PC-FA); and with blast furnace slag (PC-BFS). Laboratory tests were conducted to measure mechanical strength, hydraulic conductivity, and freezing-thaw resistance of mixtures. Life-cycle assessment (LCA) approach was used to quantify greenhouse gas (GHG) emission and energy consumption of pervious concrete mixtures with different material compositions. Mass and economic allocation methods were applied to quantify the effects of allocation on impact assessment of fly ash and slag. Laboratory test results show that as compared to the regular pervious concrete, pervious concrete mixtures with slag or fly ash had the similar freeze-thaw resistance but the lower mechanical strength, especially in tensile or flexural strength. The hydraulic conductivity of pervious concrete mixtures with fly ash and slag was found slightly higher due to the larger air void ratios. The choice of allocation methods was found to have significant effect on the assessment results. The adoption of economic allocation method showed 6-9% lower energy saving and 11-19% GHG emission reduction as compared to the mixture with Portland cement. The overall performance of each pervious concrete mixtures was quantified through internal normalization and the area covered in the radar diagram. The pervious concrete with fly ash exhibited the highest overall performance considering the balance of multiple-criteria in engineering properties, cost saving, energy and GHG reduction. (C) 2019 Elsevier Ltd. All rights reserved.