CRCP on the N49 – How the repair of the longitudinal joint leads to a better view on the crack formation of CRCP

Abstract

The N49/E34 is a regional road reconstructed in 2005 by a classic design with 230 mm of CRC on an asphalt interlayer and a lean concrete base. The portion of the road near Assenede was constructed in two stages, with tie bars in the longitudinal construction joint. During construction a problem occurred with the automatic insertion of the tie bars and the contractor had to switch from inserting the tie bars into the fresh concrete to drilling and gluing the tie bars into the hardened concrete. After some years, widening of the longitudinal joint – locally up to 40 mm – was measurable, owing to the malfunctioning of the anchorage in the joint. The closure of a stretch of the road for repairs provided an opportunity for detailed measurements of crack distribution. A difference between the fast lane, which was still bonded to the asphalt interlayer, and the slow lane, which was completely debonded, was clearly visible in the crack pattern. This paper first analyses the problem at the longitudinal joint. In order to determine the cause of the joint widening, ultrasonic tomography was used for a non-destructive analysis, and a visual inspection was made on core samples drilled along the longitudinal joint. A second part will deal with the repair method for the longitudinal joint. A short description of the different feasible methods will be given; cross-stitching was eventually chosen. Details of the rehabilitation work in practice will be shown. Finally, the difference in crack pattern and crack distribution between the slow and the fast lane will be discussed. The failure of the longitudinal joint on a portion of the N49/E34 provided an opportunity to investigate the behaviour of the CRCP more thoroughly, which resulted in a nice test section for measurements of the crack pattern.