Department of Civil and Environmental Engineering
Brigham Young University
Asphalt Patching and Scarification
"While the saw-cut method produces a smooth vertical face on the existing asphalt pavement, the portable recycling machine imparts a rough scarification to the pavement edge. The purpose of this research was to investigate the effects of scarification on patch joint bond strength."
Woffinden, Guthrie, and Eggett
Constructing patches in asphalt pavements typically involves sawing vertical cuts into the roadway surface and laboriously breaking up and removing the deteriorated material before repaving. An appealing, alternative removal technique utilizes a portable asphalt recycling machine that simultaneously cuts and pulverizes the asphalt concrete. While the saw-cut method produces a smooth vertical face on the existing asphalt pavement, the portable recycling machine imparts a rough scarification to the pavement edge. The purpose of this research was to investigate the effects of scarification on patch joint bond strength. An experimental pavement section was constructed in Pleasant Grove, Utah, to specifically compare the bond strengths of saw-cut and scarified patch joints. Twenty-five cores were extracted from each patch joint both before and after winter to additionally evaluate the effects of in-situ freeze-thaw cycling on the bond strength of each joint. The density and shear strength of each core were measured, and statistical techniques were employed to separate the effects of scarification and density on bond strength. Analysis-of-covariance (ANOCOVA) testing was used to compute adjusted mean bond strengths at the average density for the saw-cut and scarified specimens. The adjusted average strengths of the scarified cores were 20.8 percent and 25.1 percent higher than the corresponding strengths of the saw-cut cores before and after winter, respectively. Furthermore, the statistical analyses showed that the introduction of a scarified face improved patch joint bond strength for all compaction densities and that the importance of achieving proper compaction during construction increases as the joint ages.
Asphalt Patching, Bond Strength, Joint Compaction, Load Transfer Efficiency, Scarification