Long Term Monitoring of Broken and Seated Pavements

This report presents details of a study conducted to evaluate the long term performance of asphalt overlays on broken and seated (B/S) concrete pavements, using field experiments. The primary purpose of this study is to evaluate the effectiveness of breaking and seating as a rehabilitation strategy for retarding reflection cracking in asphalt concrete (AC) overlays on jointed reinforced concrete pavements. Test sections were constructed by milling the original AC layer, breaking and seating the concrete slabs and constructing new AC overlays. Control sections were constructed adjacent to the B /S sections in the same way, but without breaking the underlying concrete slabs. The test sections carried a large volume of traffic. The original pavements selected in this study were fairly uniform with respect to their structural and surface conditions. Two types of pavement breakers were used in this study, namely guillotine and pile hammer. The extent of breaking was closely monitored. The performance of the test sections was monitored for a total period of nine years. The monitoring data included deflection measurements, crack mapping, a pavement condition survey and roughness surveys on the original pavement and on the overlay. The results, in general, strongly indicate an improved performance of AC overlays on broken and seated concrete pavements. The B/S treatment has a significant effect on the structural response and behavior of the resulting pavement. Breaking the concrete slabs into smaller pieces resulted in a reduction in the flexural strength, an increase in the surface deflection (50% to 100%), and a decrease in AREA and Spreadability (20 to 30%). Breaking and seating has been extremely effective in delaying and minimizing reflection cracking. Hence, the breaking and seating procedure does indeed result in improved pavement performance. Ultimately, economics and serviceability will govern its use, based on the length of time future maintenance and rehabilitation is deferred.