Comparison of Thin-Lift Hot-Mix Asphalt Surface Course Mixes in New Jersey

The use of thin-lift hot-mix asphalt (HMA) surface course mixes has gained wide acceptance in the United States as a means of improving ride quality and safety. Generally, these materials are classified as having an open-graded and gap-graded aggregate skeleton, nominal aggregate sizes of 12.5 mm or less, and higher than normal asphalt binder contents and are placed in thicknesses of less than 1 in. (25 mm). The use of the thin-lift materials has been found to improve wet-weather driving conditions, reduce traffic noise associated with the tire-pavement interface, and improve ride quality measurements. Typically, thin-lift HMA surface course mixes found in New Jersey consist of open-graded friction courses and Novachip, with a few roadway sections using microsurfacing and stone-mastic asphalt. Each of these material types is evaluated to provide an assessment of their ride quality and safety. These thin-lift materials are compared with in-service dense-graded asphalt mixes and portland cement concrete (PC...