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from field testing, not all roads with chip seals exhibitedstripping. Information provided by city <br />engineers for field sites locations identified less than Moderate levels of stripping in 6 of the 18 primary <br />field sites. Condition information relative to volumetric core data (percent air voids and maximum <br />density) is described in Figure 12. <br /> <br /> <br />Figure 12. Severity of stripping in chip-sealed pavements in 18 locations with maximum theoretical density and <br />percent air voids <br />Figure 12 does not describe an observable trend relating the extent of stripping to air void content. As <br />the air void content for all sections examined is 8.5 percent or lower, no sections with excessive air voids <br />were considered in the study. Thus, it is difficult to correlate stripping behavior directly with excessive <br />air voids or air void content in general. <br />In addition, previous to the MnDOT study published in 2013 (Wood & Cole, 2013), many state and <br />city/county engineers supposed that there may exist a relationship between (A) a specific bituminous <br />mixture, contractor, geographic location, or year of construction and (B) the likelihood and extent of <br />stripping. Table 12 summarizes data addressing this hypothesis. One limitation of the project was the <br />lack of pavement information from municipalities on the sections considered; much of the information <br />provided lacked specific detail on the mix design, for instance. However, based on the data available to <br />this project, a correlation is not apparent between stripping in chip-sealed pavements and a specific mix, <br />contractor, or paving year. <br />32 <br /> <br />