Comparison of Surface Characteristics of Hot-Mix Asphalt Pavement Surfaces at the Virginia Smart Road

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Virginia Tech

Pavement surface characteristics are important to both the safety of the pavement surface and the comfort of the drivers. As of yet, texture and friction measurements have not been incorporated into the design of pavement surfaces. Seven different wearing surface mixtures, placed at the Virginia Smart Road pavement facility, were studied over a one year time period for both friction and texture properties. A locked wheel skid trailer and a laser profilometer were used to assess the pavement surface characteristics. Laboratory testing of the pavement wearing surface mixtures was performed to determine volumetric and mixture specific characteristics. Testing included gyratory compaction, specific gravity, maximum theoretical specific gravity, ignition testing, and gradation analysis. These material properties were used to study the impact of material properties on pavement surface characteristics. The pavement surface characteristics were analyzed using regression analysis with some measured and calculated parameters relevant to the pavement wearing surface properties. Analysis variables included the skid number at 64 kilometers per hour measured using the ASTM E501 (smooth) and ASTM E524 (ribbed) tires, the mean profile depth, the slope of a linear SN-speed model, the skid number at zero speed from the Pennsylvania State University (1) model, and the International Friction Index parameters.

Analysis determined that testing particulars such as the grade of the test did not significantly affect the measured skid number. However, there is a significant difference between the skid numbers measured using the two tires. Additionally, the relationship between speed and skid resistance is assessed differently between the two test tires. Regression analysis concluded that there is a relationship between surface characteristics and HMA design properties such as the VMA, VTM, Percent Passing #200 sieve, and Binder Type. The influence of these variables on each of the analysis parameters varied.

Texture, Hot Mix Asphalt Properties, Pavement Surface Characteristics, Skid Resistance