CPR TECHNIQUES IN ONTARIO - 15 YEARS EXPERIENCE

In the summer of 1989, the Ministry of Transportation of Ontario (MTO) undertook the rehabilitation of an exposed concrete pavement exhibiting various distress manifestations. Highway 126 in Southwestern Ontario is a four-lane divided arterial with 22,000 AADT and 9.6% commercial traffic in year 2000. The existing pavement, originally constructed in 1963, consisted of 230 mm mesh reinforced Portland Cement Concrete (PCC) pavement with dowelled joints at a spacing of 21.3 m. The rehabilitation of the highway in the northbound lanes (NBL), which had experienced moderate deterioration, consisted of using the latest concrete pavement rehabilitation (CPR) techniques, material specifications and construction methods. The rehabilitation techniques included full depth repair, partial depth repair, diamond grinding and joint sealant replacement. The southbound lanes (SBL) received a 180 mm thick plain jointed unbonded PCC overlay to address the severe 'D' cracking and spalling at all the joints and cracks. This paper will discuss the fifteen-year evaluation of this rehabilitated pavement in terms of roughness measurements using the Automatic Roughness Analyzer (ARAN), frictional resistance measured with the ASTM brake-force trailer, and Pavement Condition Ratings. Also included will be a discussion on subsequent localized concrete pavement repair work completed on the highway during the fifteen years. Monitoring the performance of the pavement over the last fifteen years has indicated that locations for partial depth repairs must be chosen judiciously to ensure that they are not greater than one-third of the slab depth. Where existing pavement joints have seized and full depth repairs are constructed at mid-slab, further deterioration of secondary minor transverse cracks can occur. Consideration should be given to carrying out full depth repairs at these locations during initial construction. Although diamond grinding significantly improved the ride of the rehabilitated pavement, the initial improvement in skid resistance has dissipated so that after fifteen years, the average SN80 is 7 units lower than the burlap dragged/tined surface. Overall, the rehabilitated concrete pavement, both NBL and SBL, is performing well, with acceptable levels of ride quality, frictional resistance and distress propagation.