Use of Manufactured Waste Shingles in a Hot-mix Asphalt Field Project

About the report:

The Virginia Department of Transportation (VDOT) is faced with trying to maintain its roads with materials whose cost is increasing at an alarming rate. The significant cost increase for asphalt concrete, which is used to pave a majority of Virginia's roads, is primarily linked to the cost increase for the petroleum products from which asphalt binder is produced. In the 1990s, VDOT developed a special provision to allow contractors, upon request, to use waste shingles in asphalt concrete. These shingles contain approximately 20 percent asphalt, which replaces part of the expensive virgin binder in the mix. In 2006, a contractor requested that the manufactured waste shingles be allowed on an overlay paving project in southeast Virginia. The 4.1-mile two-lane section was paved using a surface mix containing 5 percent shingle waste and a surface mix containing 10 percent recycled asphalt pavement for comparison. Density tests were performed on the pavement, and various laboratory tests such as permeability, fatigue, tensile strength ratio, rut, and binder recoveries were performed on samples of mix collected during the construction of the section. Both the field and laboratory test results indicate that the behavior and performance of the two mixes should be similar. The study recommends that VDOT's Materials Division prepare a permanent special provision to allow the manufactured waste to be used in asphalt. Because of the success of using manufactured waste, tear-off shingle waste resulting from replacing home shingles should also be investigated. Although manufactured waste shingles are available only in the northeastern part of North Carolina, several Virginia counties near the North Carolina border may be able to realize a cost reduction if shingles are used in the future. There is potential for approximately 50,000 tons of hot-mix plant mix containing waste shingles to be supplied to VDOT's Hampton Roads District per year. It was estimated that as much as $2.69 could be saved for every ton of asphalt that uses the waste shingles.

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