Visual inspection is the state-of-practice in deciding the type and location of repairs in road rehabilitation projects. Field non-destructive testing (NDT) can provide information on pavements performance to help make such decisions. NDT was carried out on City of Winnipeg’s regional roads. The projects included two rigid pavements and one composite structure and they were scheduled for rehabilitation in 2017.
Falling Weight Deflectometer (FWD) testing was performed prior to and after milling and full-depth repairs to evaluate the effect of the asphalt overlay on load transfer efficiency, as well as the improvement in joint performance achieved by full-depth repairs. Real Time Kinematic (RTK) surveying equipment was used to capture coordinates of test locations for retesting after milling or full-depth repairs. This study also evaluates how pavement deflection measurements can be incorporated at the design stage to facilitate the decision making process and to optimize rehabilitation costs with the availability of joint performance information.
Hundred fifty joints were tested in total and their performance was evaluated through their load transfer efficiency, peak deflection and differential deflection between the approach and leave slabs at the joint. It was found that load transfer efficiency measurement experienced a considerable reduction once the asphalt overlay was milled. This means that testing concrete joints performance before milling overestimates their performance and could lead to different repair decisions. Joints generally achieved over 90% load transfer efficiency following a full-depth repair. In cases where the load transfer efficiency was low after a full-depth repair, the peak and differential deflections were found to be small. This highlights the importance of including peak and differential deflection criteria in evaluating performance. Moreover, it was found that in one project approximately 22% of tested joints were under-performing in terms of load transfer efficiency, while 50% of them received full-depth repair. The cost of such repair could have been optimized with the availability of such information. This study sheds light on the benefits of FWD information in the decision making process of joint repairs.