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

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