Life-cycle assessment of roadway pavements for the adaptation and mitigation of climate change impacts
Creators: name: Chen, Xiaodan
Publisher: name: No Publisher Supplied
Year: 2021

description: It has been documented that human activities are changing global climatic patterns, increasing the risk and vulnerability of transportation infrastructure. Warming temperatures and more heavy precipitation may consequently cause rapid pavement damage and roadway failure. To reduce greenhouse gas (GHG) emissions and avert adverse impacts caused by climate change, governments and agencies progressively prepare climate action plans focused on greenhouse gas mitigation and climate adaptation. life-cycle assessment (LCA) is one of the most appropriate tools to assess the GHG emissions and other environmental impacts of transportation infrastructure. This research first improved the methodology of life-cycle assessment (LCA) to increase the accuracy in quantifying GHG emissions, then applied the improved method to evaluate the effectiveness of the proposed mitigation and adaption strategies. The environmental assessment categories include GHG emissions, energy consumption, and other environmental impacts such as runoff quality improvement made by permeable pavement.The methodology of LCA was improved in two aspects. First, this study proposed to consider the temporal aspect of GHG emissions by calculating CO2 emission with decay effect, which was applied in the case study of runway rehabilitation using reclaimed asphalt pavement (RAP). Second, there is a debate on whether industry waste or byproducts should allocate part of the environmental burden from their main production processes. This study investigated the mass allocation and economic allocation methods of supplementary cementitious materials (SCMs) used in pervious concrete mixes. Pervious concrete pavement as one of the adaptation strategies in response to heavier precipitations under climate change has great potential in reducing stormwater runoff volume and improving the runoff water quality. With partial replacement of cement with fly ash, a full LCA of pervious concrete pavement system applied in parking lot was conducted to quantify the GHG emissions and storm water quality improvement in use stage under future precipitation. The results show that the environmental impact of pervious pavement is affected by the mix design of pervious concrete, the pervious concrete layer thickness from structure design, and the reservoir thickness from hydrologic design. Moreover, this research conducted a two-step study to understand the interaction between warming temperatures and highway pavement of the traffic lanes. First is quantifying the impact of warming temperatures on asphalt pavement overlay performance due to climate change and evaluating the feasible adaptation strategies in overlay design and construction. The study found that warming temperatures contributed to the faster pavement deterioration, especially fatigue cracking, reducing pavement service life by 2-3 years. Based on these findings, this study conducted a complete LCA to calculate CO2 emissions in the pavement life cycle, including phases of raw materials, plant production, transportation, field construction, traffic delay, and use. In particular, the time-dependency of CO2 emission was considered to increase the accuracy in estimating cumulative radiative forcing. It was found that warming temperatures would lead to earlier or more frequent overlay treatments. The LCA results show that climate change causes greater CO2 emission abundance over the years during the study period of future 35 years.In response to climate change, this study proposed the following approaches for road transportation for mitigation and adaptation. For the adaptation of increasing heavier precipitations, applying pervious concrete pavement in parking lot would improve the storm water runoff quality and reduce the runoff volume. For the warming temperatures, using recycled material such as recycled asphalt pavement, fly ash, and slag help mitigate GHG emissions; increasing asphalt pavement overlay thickness, controlling the in-place air void during construction, and optimizing the rehabilitation strategies of highway pavement would be environmentally and economically sustainable adaptations in the climate-changed world.