In the fall of 1984, the Kansas Department of Transportation constructed a project involving cracking, seating, and overlaying a portland cement concrete pavement. The project is located in Wyandotte County on K-7 highway, north of K-32. This project is on the west side of the Kansas City metropolitan area. Eight experimental sections and one control section were stipulated for this project. One section of regular construction was selected for the control section. Four of the eight test sections were designated to be cracked at 0.9 m (3 ft) centers, and the other four were cracked at 1.5 m (5 ft) centers. One half of each spacing pattern was saw cut at the quarter points of the 18.7 m (61.5 ft) panels [approximately 4.6 m (15 ft) spacing, minimum 127 mm (5 in.) deep, maximum 13 mm (0.5 in.) wide] prior to cracking. Four sections had minimal joint repair; four had normal joint patching. There have been no easy determinants as to why the transverse cracking is low in some sections, and high in others. In some years it appears to be one factor, but the next year the factor has appeared to change. After 10 years there is no difference attributable to the cracking spacing, probably because both spacings are too large to adequately distribute the thermal movements. Slightly better performance was noted in sections that have minimal joint patching. More recent projects have used rubblizing as a rehabilitation technique. These have not shown significantly better performance than the cracking method. More investigation needs to be done to quantify the effect of various components that are used in this technique.

Asphalt concrete overlays of a jointed or cracked portland cement concrete (PCC) pavement can develop reflective cracking because of either horizontal or vertical movement of the PCC. One method that can be used to reduce reflective cracking is to crack and seat the PCC prior to placement of the asphalt concrete overlay. The description, applicability, benefits, limitations, costs, recommended uses, and location of demonstration sites for cracking and seating technology are discussed.

This synthesis will be of interest to pavement designers, maintenance engineers, and others interested in reducing reflection cracking of asphalt overlays on portland cement concrete (PCC) pavement. Information is presented on the technique of breaking or cracking of the concrete pavement into small segments before overlaying with asphalt concrete. Asphalt concrete overlays on existing PCC pavements are subject to reflection cracking induced by thermal movements of PCC pavement. This report of the Transportation Research Board discusses the technique of breaking/cracking and seating of the existing PCC before an overlay as a means to reduce or eliminate reflection cracking.