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Asphalt shingles make up roughly two thirds of the U.S. residential roofing market. Approximately 10 million tons of waste asphalt shingles are generated each year through reroofing activities in the U.S. Manufacturing produces another 1 million tons of asphalt shingle scrap per year. As a substantial portion of the C&D waste stream and because they are usually separated from other debris, asphalt shingles have the potential to be recycled. The aim of the project was to separate the different components of asphalt shingles and test their properties.
In this project 2 samples of asphalt shingles were taken, one being the new shingles and the other being old and used shingles. All the testing was done in TxDOT. Shingles were first heated and shredded into smaller pieces. In order to separate the various components in asphalt shingles, it was fed into a centrifuge through which trichloro- ethylene was passed. This dissolves the asphalt and gives it in the form of a solution where as the fibers and the aggregates would be completely separated from it. The fibers and aggregate mix was separated by sieving them. The asphalt was recovered from the mixture of trichloro ethylene and asphalt, and it was tested. Testing was done using DSR and the hardness of the asphalt was determined. It was seen that the asphalt obtained from asphalt shingles was really hard but it can be used for a number of applications such as in hot mix asphalt, cold patch, dust control on rural roads, temporary roads or driveways, aggregate road base, new shingles and as fuel.
Using recycled asphalt shingles (RAS) in new products is important to reduce the negative environmental impacts associated with the extraction, transportation, and processing of virgin materials. It also conserves valuable landfill space. In addition, the use of these recycled materials reduces the amount of virgin resources used in production and reduces costs for manufacturers and consumers. Researchers have found that using recycled asphalt shingles in hot-mix can actually improve the pavement’s performance by increasing its resistance to wear and moisture, and decreasing deformation, rutting, and thermal fatigue and cracking.
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