Durawhisper™

Durawhisper™ consists of a 10mm nominal size, dense-graded asphalt mixture designed with 2 to 4 percent air voids. The aggregate particle shape and the design of the stone skeleton provide excellent rutting resistance and vehicular traffic noise-reducing characteristics. Crumb rubber, which is added to the asphalt mix, is beneficial for improved durability and long-term performance, particularly when subject to heavy slow-moving traffic.

The combination of the crumb rubber additive and the use of a polymer-modified binder provide increased resistance to reflective cracking initiated when paving overlays to existing concrete slabs.

Its traffic noise-reducing properties make Durawhisper ideal for surfacing in and around subdivisions and general residential areas.

Tire-rubber crumb asphalt can be added in two ways (both requiring additional, specialized equipment):

1. Wet process: The asphalt rubber binder contains 15 to 20 percent tire-rubber crumbs from processed tires. The asphalt binder and tire-rubber crumbs are mixed together at elevated temperatures to achieve a homogenous binder.

2. Dry process: 1 to 2 percent tire-rubber crumbs are mixed in as a dry aggregate.

Durawhisper^® has been subjected to a rigorous performance testing regime, providing the following performance results:

• Maximum laboratory wheel-rut depth of 5 millimeters after 8,000 cycles at standard PGAC high temperatures, AASHTO TP 63;
• Minimum fatigue resistance to failure of 230,000 cycles at 480 μmand 18 degrees C (AASHTO T 321)
• Reduced tire noise by 8 dB (1.0 millimeter offset X 1.0 millimeter height roadside measurement).