Short-Term Skid Improvements by Light Texturing with a Milling Machine

US Transportation Collection2020PDFTech ReportGao, LuSmit, Andre de FortierProzzi, Jorge AlbertoBuddhavarapu, PrasadMurphy, MikeSong, LingguangUniversity of Houston. Department of Civil and Environmental EngineeringTexas. Dept. of Transportation. Research and TechnologyUnited States. Department of Transportation. Federal Highway AdministrationUniversity of Houston. Dept. of Civil and Environmental EngineeringUnited StatesBefore and after studiesHot mix asphaltMacrotextureMillingRecommendationsSeal coatsSkid resistanceStatistical analysisTest sectionsPavement groovingLight TexturingPavement TextureMilling MachineFHWA/TX-20/0-6752-1, 0-6752-10-6752Technical Report, Sept. 1, 2012 \u2013 Aug. 31, 2014Skid problems on roads can result from flushing and bleeding where excessive road-mix binder can accumulate on a road\u2019s surface as well as general wear of the surface by traffic. This may result in a polished surface that may increase the chances of accidents due to the reduced skid resistance. Strategies to address this problem include mill and fill or overlay rehabilitation but another cost effective solution is to remove only the top portion of the surface course using light-texturing or micro-milling. Unlike a typical mill-and-fill operation, there is not an additional step in laying a new wearing course after milling has been completed. Instead, the newly exposed surface will already have the desired final texture and noise properties, and can be opened to traffic sooner. Some Texas districts have already implemented this technology and have achieved substantially improved skid resistance and reduced rutting with no detrimental effects to the existing pavement. However, these texturing improvements have not been studied to determine how well they improve skid and how long that skid improvement lasts. In this research, light texturing of pavement had been conducted at thirty one sections across Texas. The research team visited each test section during the milling and used different configurations of milling depths and machine forward speeds. While Sand Patch Test, Circular Track Meter and 3D laser scanner were used to obtain the pavement surface texture, British pendulum and skid truck were used to obtain the skid resistance before the milling and at 0, 3, 6, 12 and 18 months after the milling. The tests are repeated 3 times at every test section for better accuracy. The Mean profile depth value is measured for left wheel path, right wheel path and middle wheel path. Based on the statistical analysis of the skid resistance and macrotexture data measured on the seal coat and hot mix asphalt (HMA) sections evaluated as part of the study, the following light texturing guidelines are recommended: (1) Finer milling drums are recommended over standard milling drums if the sections have higher initial skid resistance (above 25 SN); (2) A forward milling speed of 70 \u2013 80 feet per minute is recommended; (3) A depth of milling cut between 0.25 and 0.5 inches may be used on both seal coat and HMA sections.120