Agenda - Council - 02/11/2020 - Laserfiche WebLink

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3.4.2 Field behaviors associated with stripping One important outcome of the study was the project survey, which identified important information in the understanding of stripping. First, the stripping behavior observed under chip -sealed pavements is not typically seen on roadways that were unsealed (four percent of engineers reported significant stripping and 21 percent of respondents reported minor stripping in unsealed roads). In this regard, the survey suggests that the presence of the chip seal treatment itself, and not properties of the underlying asphalt, may contribute to stripping. While not as thorough as the lab and field studies, the project research included surveys of field sections in cities and counties to study how a chip seal may encourage stripping. Municipal engineers have observed that often in roads featuring neighboring chip -sealed and unsealed portions, the chip -sealed roadway will exhibit stripping behaviors, while the unsealed portion experiences only surface raveling. One type of road that was useful for such a survey was a road ending in a cul-de-sac, as these roads are often chip -sealed on their straight portions while the cul-de-sacs are unsealed. The project included one such road, Newbury Alcove in Woodbury, MN. The relative material lost due to stripping can be seen in comparing Figure 13b and Figure 13d. One confounding factor in this observation, however, is the fact that the Hamburg Wheel test found that the straight portion mix was the only mix susceptible to stripping due to moisture damage. 34