Use of Recycled Material in WMA- Future of Greener Road Construction
Ankit Sharma, Praveen Kumar, Ashish Walia
Abstract
Sustainable road construction practice requires an asphalt mix technology that is environmental friendly, energy-efficient, economical and protective for humanity and health. India and many other countries are using Hot Mix Asphalt (HMA) technology for asphalt road construction. HMA has several disadvantages like high production temperature (155˚C to 165˚C), which increases Green House Gas (GHG) emissions. These emissions increase Global Warming and severely affect the respiratory system of paving crew workers. Warm Mix Asphalt (WMA) technology can reduce the mixing and compaction temperature by around 30˚C in comparison to HMA. WMA has many advantages over HMA like fuel-saving, reduced emissions, improved visibility at the site, more incorporation of Reclaimed Asphalt Pavement (RAP). RAP is the old aged flexible pavement material that can be recycled back to construct a new pavement. Researchers found two major issues with the use of RAP in asphalt mixes such as high emission during mixing of RAP with virgin aggregate and premature cracking due to aged (stiff) binder. WMA may resolve these two issues, first by reducing binder’s viscosity at lower production temperature (reducing high emissions during production of asphalt mix) and second, reducing secondary aging of RAP aged binder. Some WMA additives also works as rejuvenators and provide good coating. This paper discusses the WMA technology, it’s classification, mix design guidelines for WMA, era of recycling, use of RAP and Reclaimed Asphalt Shingles (RAS) into WMA and role of rejuvenators in WMA.