The effect of carbonation after demolition on the life cycle assessment of pavements

Abstract

The high contribution of CO₂ emissions associated with pavements has driven research to assess the life cycle of concrete versus asphalt structures and to develop a strategy to reduce the carbon footprint. The life cycle of pavement has been studied with respect to CO₂ emissions in the use phase of concrete as well as after the concrete is demolished. However, only a few have considered the effects of CO₂ uptake in the carbonation process during the use phase, and even fewer have studied the effects of carbonation after demolition. This work fills the gap between estimates of carbonation in a life cycle assessment for pavements by considering the effects of the storage method on the uptake of CO₂ after the concrete demolished. It is observed that how the concrete is stored after demolition can have an influence on the CO₂ uptake of the structure. There is also an increase in the amount of the CO₂ emitted during the calcination process that is taken back up by the concrete structure during the carbonation process to a level of 6 - 30% from previously predicted values of 5-10% which assume no carbonation after demolition. The incorporation of carbonation after demolition into a comparative life cycle assessment between asphalt and concrete pavement is used to better predict the pavement material with the lower environmental impact considering variations in the climate zone, traffic level, maintenance schedule, design life and analysis period.