Analysis of Carbon Emission during Hot In-Place Recycling Asphalt Pavement Construction

To analyze carbon emission during hot in-place recycling asphalt pavement construction, the construction period is divided into material production and pavement construction using the life cycle analysis method. Then, a carbon emission model is established according to the multiplication principle of the carbon emission coefficient and activity data. On the basis of an engineering example, carbon emission during pavement construction is calculated; carbon emission with different new material ratios, recycled material haul distances, and utilization rates of recycling asphalt mixture is quantified; and the carbon emissions of four pavement maintenance technologies are compared. Results show the following conditions. (1) The carbon emissions of material production and pavement construction account for 20% and 80%, respectively. (2) Carbon emission increases by 2% with an increase of 1% in hot in-place recycling new material ratio. (3) The haul distance of recycled asphalt mixture is 42 km when hot mix plant recycling with 100% utilization rate of recycled asphalt mixture produces equal carbon emission with hot inplace recycling. When the haul distance is over 42 km, the carbon emission of hot in-place recycling is less than that hot mix plant recycling. When the utilization rate of recycling asphalt mixture is lower than 75%, the carbon emission of hot in-place recycling is always less than that of hot mix plant recycling regardless of haul distance. (4) Compared with that in hot in-place recycling, the increase in amplitude of carbon emission on micro-surface, ultra-thin overlay, and mill-and-resurface asphalt pavement is 53%, 72%, and 79%, respectively.