Life-Cycle Assessment of Reconstruction Options for Interstate Highway Pavement in Seattle, Washington

Life-cycle assessment (LCA) is a tool that can be used to identify the environmental impact of a product or process. This paper compares three replacement options for an aging portland cement concrete (PCC) pavement with the use of an LCA process-based protocol. The options are to remove and replace the aging pavement with PCC pavement; remove the aging pavement and replace it with hot-mix asphalt (HMA) pavement; and crack and seat the existing pavement and then place an HMA overlay. Each option investigated includes a detailed construction and rehabilitation schedule and is analyzed over 50 years. The results show that materials production (e.g., cement, asphalt, PCC, and HMA) dominates the energy use, emissions, and impacts for all three options. In general, HMA production tends to cause the HMA option to have the highest energy use, whereas cement production tends to cause the PCC option to have the highest global warming potential (GWP). The crack, seat, and overlay option was the lowest energy user, had the lowest GWP, and produced the least emissions in more categories measured than the other two options. This may become a strong argument for expansion of the crack, seat, and overlay method of rehabilitation.