Asphalt binders modified with ground tire rubber (GTR) have several positive qualities. Adding ground tire rubber to asphalt can contribute to improved rutting resistance, skid resistance, ride quality, pavement life and reduced pavement noise levels. Adding rubber to the asphalt liquid retards aging and oxidation of the resulting binder, which increases pavement life by lessening brittleness and cracking. Rubber-modified asphalt binders can be used in open-graded asphalt mixtures, which have reduced hydroplaning, vehicle spray and reduced pavement noise.
But how much is really added to a mix at the plant? How can DOT's be sure the specs are met? Extraction could be the answer. One of the more recent technological developments comes in the form of a testing device to extract asphalt binder from hot-mix asphalt (HMA) mixes and automatically separate the components for analysis. Rather than devoting days to traditional reflux extraction to determine binder content from an HMA sample, or relying on ignition ovens and correction factors, technicians in DOT's around the country are turning to the Asphalt Analyzer manufactured in Germany by infraTest.
This automated extraction method avoids technician exposure to highly flammable and dangerous solvents such as trichloroethylene and can provide results in about 90 minutes. According to infraTest USA, the new PG model is equipped with a second solvent circuit allowing for the extraction of rubber modified asphalt mixes as a stand-alone procedure. This becomes more critical as rubber use in pavements increases, and as new processes are implemented for incorporation of the rubber.