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Chapter 1.Introduction <br />Objectives of Research and Methodology <br />This report represents task 6 –Draft Final Report of Local Road Research Board (LRRB) project <br />number 904, Minnesota State Planning and Research project number MPR 10-(042)study <br />entitled, “Stripping of Hot-Mix Asphalt Pavements under Chip Seals” <br />. <br />The objectives of this research project wereto determinewhysome streets suffer from stripping <br />of the hot-mix asphalt (HMA)pavement afterplacement of asphalt chip seal.Using this data we <br />will recommend how to determine if streets will suffer from strippingprior to chip sealing.Also <br />recommendations will be made on how to improve performance of streets starting with pavingof <br />the asphalt pavement. <br />The research efforts where made up of the followingtasks: <br />Task 1 Survey Cities and Counties to determine the extent of the stripping under chip <br />seals. <br />Task 2 Develop and modify existing test methods to determine is the HMA in place on <br />streets is prone to stripping. <br />Task 3 Coreand testthecores from City streets. <br />Task 4 Reviewpast and presentconstruction methodsof citiesfor asphalt paving streets. <br />Task 5 Analyzed thetest results from cores. <br />Task 6 Draft final report <br />Task 7 Final Report <br />Task 8 Implementation Plan <br />Background: Stripping Under Chip Seal Distress <br />For more than twenty years, Cities have experienced pavement deterioration of the upper 0.5 to <br />1.0 inch of HMApavements under chip seals. The distress causing this is stripping of the <br />asphalt layer directly beneath the chip seal (Figures 1 and 2). This distress starts as a small <br />blister and becomes enlarged to the size of a small pothole; at which time the chip seal <br />delaminates off of the asphalt pavement. <br />With the high cost of asphalt, the use of pavement preservation treatments has grown rapidly as <br />agencies preserve their roadway system. Most of the incidents of this distress have been <br />located on urban curb and gutterstreets. If the distress is localized small patch will restore the <br />street. However, as the area of deterioration expands a thin mill and overlay may be required to <br />restore the street. This distress may lead to an expensive maintenance problem. <br />1 <br /> <br />