LowEmissionAsphalt-136pg-WhitePaper-May2023

P a g e | 42 There remain lifecycle questions related to aggregate adhesion and poor sorptivity from WMA mixtures, but specialized mix additive technologies to assuage these issues are showing promise. Nineteen percent (19%) of asphalt mixes produced in 2019 used WMA technologies for energy reductions. 88 However, the estimated GHG emissions reductions ranged 0.05 to 0.21 million tons or well <1% of industry total emissions. 89 So, virtually no carbon reduction benefit because the typical temperature reductions achieved fell well below 40°F. Polymerized Modified Asphalt PMAs primarily improve pavement density on high traffic roads and blends contain recycled materials such as used tires to help alleviate landfill scarcity. Mixtures, however, are viewed as difficult to pave with due to poor workability and they unfortunately are more energy consuming to manufacture . Compatibility issues raise lifecycle concerns. Road wear also releases these plastics , mainly styrene butadiene styrene (SBS), back into the environment over time, creating air quality and oceanic contamination concerns. SBS from modified asphalts is the third largest source of roadway microplastic pollution. 90 “But [our] concern is if you put [polymers] in the wearing course, that you will create microplastics. One of the significant issues for us is road wear particulates. This has only become a mainstream issue recently, but it is a key challenge for the highway sector.” – AECOM Cold-in-Place Recycling CIR is used for base reconstruction and is a highly effective way for agencies to lower repaving costs for severely deteriorated pavements as a part of full-depth recycling. The technique can save up to 10% of the capital outlay of a rebuild but may have only a modest positive impact on carbon . 88 NAPA. 89 NAPA. 90 Rodland E, Ecotoxic potential of road-associated microplastic particles (RAMP) , Norwegian Institute for Water Research, November 2019.