Standard Washington State Hot Mix Asphalt Types This section lists the standard HMA mixes used in Washington State both today and prior to changing from the Hveem mix design method. Most modern HMAs are listed to designate both the nominate maximum aggregate size of...
Superpave “Superpave” is an overarching term for the results of the asphalt research portion of the 1987 – 1993 Strategic Highway Research Program (SHRP). Superpave consists of (1) an asphalt binder specification, (2) an HMA mix design method and...
Asphalt Treated Base (ATB) Asphalt treated base (ATB) is a dense-graded (but more permeable) HMA with a wide gradation band and lower asphalt content intended for use as a stabilizing base course and intended to be used in conjunction with a top/ wear course of...
Recycled HMA HMA is one of the most recycled products in the U.S. As much as 100 million tons of HMA are milled off roads during resurfacing and widening projects each year. Of this amount, 80 million tons (80 percent) are recycled as “reclaimed asphalt...
Drainage Proper drainage is important to ensure a high quality long lived pavement; moisture accumulation in any pavement structural layer can cause problems. Moisture in the subgrade and aggregate base layer can weaken these materials by increasing pore pressure and...
Environment A pavement must function within its environment. The environment can vary greatly across the State at any one time and it can also vary greatly throughout time at any one place. Environmental variations can have a significant impact on pavement materials...
