The Illinois Department of Transportation (IDOT) has announced plans to construct three overlay demonstration sections featuring the most environmentally friendly hot mix asphalt (HMA) surface mixture ever developed in Illinois and perhaps the nation.
Dubbed “Total Recycle Asphalt,” the HMA paving mixture contains more than 97% reclaimed and recycled materials. The demonstration projects using total recycle asphalt are expected to reduce paving costs.
“We recycle and use over a million tons of reclaimed materials on our highways annually as a matter of everyday practice,” says Illinois Transportation Secretary Ann L. Schneider. “We believe Total Recycle Asphalt will take Illinois to a new level of environmental sustainability, and we hope it will inspire others to follow our lead.”
The demonstration projects will help the department evaluate the mix, measure the overall cost, and establish its performance over time. Using Total Recycle Asphalt is expected to produce savings of about 20% for IDOT and local agencies using the new mix, compared to similar traditional HMA mixes.
A demonstration project is when a new material or construction method is utilized. This provides an opportunity for the department to see first-hand how the new material or method works. It is then evaluated to determine if it should be considered as a part of the common process.
Recycled components of this surface mix include reclaimed asphalt pavement (RAP) from pavement millings, crushed concrete from public works projects, steel slag, a by-product from production of steel, and recycled asphalt shingles (RAS) from re-roofing of houses.
There was no requirements for newly mined aggregate for the mix. Additionally, only a small amount of new liquid asphalt is required in mix production for durability. The new liquid asphalt provides a very soft grade of asphalt to effectively counter the hard and aged recycled asphalt from reclaimed pavement and shingles.
IDOT’s Region 1 Materials Lab over several months has developed a number of trial mixes, while testing different combinations of various reclaimed materials.