Integrated Sustainability Assessment of Asphalt Rubber Pavement Based on Life Cycle Analysis

This study aims to quantify and compare the life-cycle environmental, economic and social impacts of two pavement materials: namely 10mm Asphalt Rubber Stone Matrix Asphalt (ARSMA10) and 10mm Polymer Modified Stone Matrix Asphalt (PMSMA10). To achieve this objective, a comparative sustainability framework was developed by: 1) combining the Life Cycle Assessment (LCA) with pavement maintenance plan developed based on the pavement conditions predicted by the Mechanistic-Empirical Pavement Design Guide (MEPDG) software; 2) examining the additional fuel consumption and emissions based on predicted pavement condition; 3) and integrating the cost-benefit analysis (CBA) to estimate the environmental damage cost and noise reduction benefit. The major findings of this study include: 1) in the 56-year analysis period, the dominant contributions to environmental impact are made by the extra vehicle greenhouse gas (GHG) emission and fuel consumption caused by pavement roughness change; 2) PMSMA10 has better environmental performance than ARSMA10 in terms of energy consumption and GHG emissions; 3) the long-term accumulated tireroad noise impact is considerable, which can almost offset its higher economic cost and environmental damage cost assuming ARSMA10 is able to decrease noise by 4%,. a comprehensive sustainability assessment of AR, this study quantified the economic, environmental, and social impacts of 10mm Asphalt Rubber Stone Matrix Asphalt (ARSMA10) through an extended life cycle assessment (LCA) approach, using 10mm Polymer Modified Stone Matrix Asphalt (PMSAM10) as a reference. LCA provides a systematic procedure to quantify the environmental performance of products throughout their life cycles. The report of FHWA (2014) divided the life cycle of pavement into five phases: production, construction, use, maintenance, and disposal. The pavement LCA studies have been documented in many literatures since 1996 (Häkkinen & Mäkelä, 1996), but the research focuses and results differ in various studies. Recent studies have combined LCA with other analysis methods to achieve results that are more comprehensive. Yu et al. (2013) integrated LCA and Life Cycle Costing Analysis (LCCA) to estimate the evidential damage cost to optimize the pavement maintenance plan. Yang et al. (2015) developed an international roughness index (IRI) progression model in the LCA to compute the GHG emissions and energy consumption of vehicles. Chong and Wang (2016) developed an LCA framework based on the pavement design and management decisions. However, noise, on which AR pavement can provide significant benefit, is often considered as one of the social-economic impacts, and has not been included and defined in the staple life cycle inventories (LCI). European Commission (2014) has assessed the noise impact by computing the corresponding noise cost introduced by the Cost-Benefit Analysis (CBA) method. In this study, the comparative sustainability framework extended the use of LCA by: 1) combining the Mechanistic-Empirical Pavement Design Guide (MEPDG) software to predict pavement conditions and determine the maintenance plan; 2) integrating the pavement conditions to examine the additional fuel consumption and emissions; and 3) integrating the CBA to examine the environmental damage cost and noise reduction benefit.