Evaluation of the 100% Recyclability of Superpave Hot Mix Asphalt

"At 2.7 million miles of paved roads, the United States has the largest network of roads in the world. The mainstream approach to pavement rehabilitation has been to mill the deteriorated asphalt and replace with new asphalt mix. The hot in-place pavement recycling process has the potential of replacing the milling and resurfacing process with substantial financial and environmental savings. Hot in-place pavement recycling restores the pavement to its original condition. The process was improved and refined over the past several years to produce the following outstanding benefits.
1. About 50% cost savings over the conventional milling and resurfacing, as indicated in FDOT’s published report on SR 471 HIP recycled pavement. This is valued as 18 billion dollars savings a year for the United States.
2. Eliminated 90% of the emissions resulting from pavement milling and resurfacing process.
3. Eliminates the growing piles of asphalt millings that threaten to pollute water.
4. Eliminates the need to haul materials from the plant to the road, and haul asphalt millings from the road to the plant. This reduces traffic at construction sites and resulting pollution.
5. Eliminates the need to mine new materials – an energy-intense operation that involves explosives.
6. Significantly cuts the need for new Asphalt Cement and reduces reliance on foreign oil. Approximately saves 15 million tons of asphalt cement, valued at 8 billion dollars a year.
7. Test Results of recycled mix showed that the recycled asphalt has more than double the required stability – Excellent indication of strength and durability.
8. Reduces down time of pavements being restored.

In 2004, Florida Department of Transportation evaluated the hot-in-place pavement recycling and performed a side by side comparison with conventional milling and resurfacing. FDOT concluded that the process was a viable option, but expressed concern that the process may not yield a Superpave equivalent mix and suggested a further evaluation. This proposal develops and experimental design of 3 factors: Nominal mix size, aggregate type and mix function and conducts laboratory tests to evaluate the hypothesis that a deteriorated Superpave mix can be successfully recycled to meet a long term performance similar to that of the virgin Superpave mix. DOT’s have started using Superpave mixes in Late 90’s. Many of those roads are now eligible for resurfacing. If the evaluation is successful, it would DOT’s to proceed with trying the process on Superpave mixes.

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