Canadian Journal of Civil Engineering Life Cycle Assessment of Asphalt Pavement Maintenance and Rehabilitation Techniques: A Study for the City of St. John’s Journal: Canadian Journal of Civil Engineering Manuscript ID cjce-2019-0540.R1 Manuscript Type: Article Date Submitted by the 09-Nov-2019 Author: Complete List of Authors: Alam, Md Rakibul; Memorial University of Newfoundland, Civil Engineering Hossain, Kamal; Memorial University of Newfoundland, Civil Engineering Butt, Ali Azhar;Draft University of California Davis, Civil and Environmental Engineering Caudle, Tim; Memorial University of Newfoundland, Civil Engineering Bazan, Carlos; Memorial University of Newfoundland, Civil Engineering Life Cycle Assessment (LCA), Pavement Maintenance & Rehabilitation, Keyword: Environmental Impacts, Global Warming Potential, Pavement Maintenance Activities Is the invited manuscript for consideration in a Special Not applicable (regular submission) Issue? : https://mc06.manuscriptcentral.com/cjce-pubs Page 1 of 28 Canadian Journal of Civil Engineering Life Cycle Assessment of Asphalt Pavement Maintenance and Rehabilitation Techniques: A Study for the City of St. John’s Md Rakibul Alam1, Kamal Hossain2, Ali Azhar Butt3, Tim Caudle4, Carlos Bazan5 Md Rakibul Alam MEng Student, Pavement Engineering, Department of Civil Engineering Advanced Road and Transportation Engineering Lab (ARTEL) Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected] (corresponding author) Kamal Hossain, PhD, PEng Assistant Professor, Department of Civil Engineering Advanced Road and Transportation Engineering Lab (ARTEL) Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected] Ali Azhar Butt, PhD, Aff. M.ASCE Assistant ProjectDraft Scientist, Project Manager University of California Pavement Research Center 3301 Apiary Drive, Davis, CA 95616, USA Email: [email protected] Tim Caudle Co-op Student Department of Civil Engineering Advanced Road and Transportation Engineering Lab (ARTEL) Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected] Carlos Bazan, PhD, PEng Assistant Professor, Department of Civil Engineering Engineering Chair in Entrepreneurship Memorial University of Newfoundland St.John’s, Newfoundland, A1B3X5, CANADA Email: [email protected] Word Count: 4,849 words + 4 figures (250 words per figure) + 5 tables (250 words per table) = 7,099 words 1 https://mc06.manuscriptcentral.com/cjce-pubs Canadian Journal of Civil Engineering Page 2 of 28 ABSTRACT Although pavement maintenance and rehabilitation (M&R) techniques are usually examined in economic terms, there is a growing need to address their environmental footprints. The objective of this study is to assess the environmental impacts of M&R techniques. LCA can help in the decision-making process of selecting suitable maintenance techniques based on their environmental impacts. This study investigates: patching, rout & sealing, hot in-place recycling, and cold in-place recycling. Global warming potential, acidification potential, human health particulate, eutrophication potential, ozone depletion potential and smog potential are estimated as environmental impacts for each maintenance activity. Materials, equipment use (for construction and M&R), and transportation were the main elements considered. A sensitivity test is performed to identify the significant factors for theDraft LCA. The study concluded that GWP was the most important impact category. Rout & sealing and CIR produced the lowest GWP emissions. Notably, pavement patching and HIR showed significant detrimental environmental impacts. Keywords: Life Cycle Assessment (LCA), Pavement Maintenance & Rehabilitation, Environmental Impacts, Global Warming Potential, Pavement Maintenance Activities. I INTRODUCTION Addressing the leading factors of climate change is one of the major global issues in today’s time. Therefore, substantial research is being conducted to study the environmental impacts of road pavement designs and construction practices using life cycle assessment (LCA) methodologies. Besides the construction of new roads, numerous maintenance and rehabilitation (M&R) projects are performed to keep roads functional. For example, the operation, construction and maintenance activities of roads in Canada cost $1160 million in 2011-12 (Transport Canada 2011). Decision support tools such as the LCA are thus needed in order to perform comparisons 2 https://mc06.manuscriptcentral.com/cjce-pubs Page 3 of 28 Canadian Journal of Civil Engineering among different pavement M&R techniques in terms of environmental impacts and make informed decision. LCA features a cradle-to-grave approach, assessing critical stages of an asset’s life. LCA requires an inventory of project parameters and corresponding data, and it provides an impact assessment system that reflects on the environmental footprint for each critical stage of the asset. For pavement, this includes material (process and production), construction, use, M&R and the end-of-life (EOL) stages. Construction and M&R stages require considerable amounts of materials and transportation and can cause significant environmental impacts especially when frequently required over the entire pavement life; thus, it is imperative to determine which maintenance techniques or practices can minimize environmentally footprints. The City of St. John’s (NewfoundlandDraft and Labrador, Canada) has a unique climate, with excessive precipitation throughout the year as well as extreme winters and moderate summers (St.John’s 2019) (Ali et al. 2018; Colin and John 1998). The City of St. John's has an annual ‘Streets Rehabilitation Program’ to rehabilitate various streets throughout the city, with an investment of over $20 million yearly (Bonnell 2016). By using LCA, the goal of this study is to determine which pavement M&R techniques among pavement patching, rout and sealing, hot in- place recycling (HIR) and cold in-place recycling (CIR) are more environmental friendly. This paper is organized as follows: Section II briefly summarizes the literature review on the topic to provide a broad perspective of previous research. The objectives of this research are described in Section III, and Section IV provides the analytic approach including the sensitivity test and experimental setup in Athena Pavement LCA. Section V provides the evaluation of the emission report and further analysis of the emission results corresponding to each maintenance and rehabilitation technique. Based on the different emission categories, Section VI comparatively 3 https://mc06.manuscriptcentral.com/cjce-pubs Canadian Journal of Civil Engineering Page 4 of 28 interprets which M&R approach is more appropriate and environmentally friendly for each emission category. Conclusions from this study are drawn in Section VII. Finally, limitations of this research and the scope for further research are discussed in Section VIII. II LITERATURE REVIEW Life cycle assessment is established as a promising technique to quantify the environmental impact of pavements in its lifetime (Santero et al. 2011). In general, most studies have been conducted by considering energy consumption and airborne emissions (most commonly greenhouse gases). This literature review has been performed bearing in mind the questions relevant to the environmental effect due to asphalt pavement M&R activities. In the past decades, numerous researchDraft has been conducted to evaluate the environmental impacts of asphalt and concrete pavements. Häkkinen and Mäkelä (1996) conducted a comprehensive comparative study to evaluate the environmental impacts of stone-mastic asphalt and doweled joint plain concrete pavement (JPCP) using LCA. They selected a 1 km roadway in Finland with a design life of 50 years as the functional unit of the study. They concluded that asphalt pavement consumed twice the amount of renewable energy as concrete pavement considering feedstock energy of bitumen (feed stock energy is defined as “heat of combustion of a raw material input that is not used as an energy source to a product system, expressed in terms of higher heating value or lower heating value” (International Organization for Standardization, 2006)). However, the environmental burdens from construction and M&R stages for asphalt pavement were lower than the impacts from high strength concrete production and construction stages (Häkkinen and Mäkelä 1996). In a different study, Roudebush (1996) quantified that asphalt pavement required 90.8% more energy than concrete pavement because of the “use” stages and more frequent “maintenance” stages. That is, more frequent maintenance including milling the 4 https://mc06.manuscriptcentral.com/cjce-pubs Page 5 of 28 Canadian Journal of Civil Engineering existing pavement surface and resurfacing it with new asphalt increases the demand for raw materials which eventually results in substantial energy consumption (Roudebush 1996). In the advent of the twenty first century, the Finnish National Road Administration (Mroueh et al. 2000) studied LCA for roads focusing on construction and M&R stages. 1 km of a highway section was selected as functional unit. Though detailed specifications of necessary construction equipment and their productivity were missing, a single environmental score system for determining total environmental burden was a novel development from the LCA research project. The authors concluded that asphalt production, crushing of