Environmental impact comparison of new micro-milling and thin overlay and conventional milling for sustainable pavement preservation

Abstract

Micro-milling and thin overlay, a new pavement preservation treatment developed and first implemented by the Georgia Department of Transportation (GDOT) in 2007, as an alternative pavement preservation to conventional milling and resurfacing, is used to remove and replace a thin, deteriorated open-graded surface layer (2.2 cm) without disturbing the sound underlying layer. This paper focuses on quantifying micro-milling and thin overlay’s environmental impacts by comparing conventional milling and overlay with micro-milling and thin overlay to complement the previous economic impact study. The environmental impacts are quantified using a pavement construction decision tool entitled Pavement Life-Cycle Assessment Tool for Environmental and Economic Effects (PaLATE). The results show a 60% reduction in all environmental impacts assessed, including energy usage, water consumption, and CO2 emissions largely due to the savings in asphalt needed. Results have demonstrated that this new method is a promising pavement preservation alternative that is environmentally sustainable. This paper provides quantitative comparison information useful for transportation agencies in selecting sustainable pavement preservation alternatives.