Life Cycle Assessment for Roadbase Construction Using Bottom Ash from Municipal Solid Waste Incineration in Shanghai

Municipal solid waste incineration (MSWI) bottom ash was used in the construction of No.17 K11+203~K11+403 section of North highway to Shanghai Pudong international airport, which was the first scenario of using MSWI bottom ash in road sub-base layer construction to replace part of gravel in large scale. In this paper road construction with or without MSWI bottom ash were compared for energy consumption and environmental impacts with the method of life cycle assessment (LCA). Energy consumption and emissions associated with the production of raw materials, transportation, construction and leaching of heavy metals were investigated respectively for the two cases. The investigation results showed that road constructed with MSWI bottom ash replacing 51% of natural gravel will save around 51% of electricity consumption and 41% of diesel consumption. The LCA results indicated that the road constructed using MSWI bottom ash in sub-base layer would lead to 84% increase in environmental impact potentials in category of ecotoxicity in water and 147% increase in human toxicity via water; while it would cause a decrease about 40% in categories of global warming, human toxicity via air and human toxicity via soil, photochemical ozone formation, acidification and nutrient enrichment compared to the case when only virgin materials is used. Those results give lights on MSWI bottom ash recycling.