Carbon emission assessment in asphalt pavement maintenance: a comparative study of five methods

Abstract

Pavement maintenance significantly contributes to carbon emissions due to its high resource and energy consumption. However, comprehensive assessments of these emissions remain limited. This study systematically evaluates the carbon emissions associated with five common asphalt pavement maintenance strategies. A carbon emission model, developed using the Life Cycle Assessment (LCA) approach, quantifies emissions across three phases: raw material production, transportation and construction. Emission inventories were derived from five practical maintenance project cases and literature. The model effectively predicts emissions in each phase. Results reveal that asphalt is the primary emission source in the raw material production phase for all methods. In the transportation phase, raw material transport, especially aggregate transportation, dominates emissions. During construction, the mixing process, particularly heating, generates the majority of emissions. Total carbon emissions, ranked from highest to lowest, are as follows: milling and resurfacing, ultra-thin wearing course, plant-mixed hot recycling, in-place hot recycling, and micro-surfacing. The raw material production phase has the greatest impact on milling and resurfacing and plant-mixed hot recycling, while emissions from in-place hot recycling and ultra-thin wearing courses are primarily concentrated in the construction phase. Although transportation emissions are significant, they constitute a smaller proportion of total emissions. These findings inform maintenance strategy decisions and suggest emission reduction measures, such as optimizing recycled material production, improving construction techniques, and adopting more efficient transportation methods to mitigate carbon emissions in asphalt pavement maintenance.