This paper presents the results of a three-year field study that compares the performance trends of various asphalt surface mixes, with and without asphalt rubber. The performances being investigated include tire/pavement noise, durability, friction, and permeability. About 80 field sections on California highway system were investigated,
which covered a variety of asphalt surface mixes: rubberized open-graded mixes (RAC-O), rubberized gap-graded asphalt concrete (RAC-G), open-graded mixes with conventional binders (OGAC), and dense-graded asphalt concrete (DGAC). Roughness, noise, and surface distress data were collected on each section for three consecutive years, and permeability and skid resistance (friction) were collected under traffic closures for the first two years.
Cores were also taken in the first two years from each section to determine air-void contents and aggregate gradations in the laboratory. The tire/pavement noise was measured by the On-Board Sound Intensity (OBSI) method. Analysis of the data indicates that RAC-G mixes provide some noise benefit compared to DGAC. However, the noise benefits are not as great as those from open-graded mixes. The noise levels from RAC-G mixes appear to approach those of DGAC after a few years in service. The data also indicate that RAC-O mixes appear to provide longer noise reduction than OGAC mixes, while both mixes provide noise and permeability benefits.