Active Crack Control in Continuously Reinforced Concrete Pavements (CRCP)

Continuously reinforced concrete pavements (CRCP) are frequently used in Belgium on roads having heavy traffic because they have a better long-term performance and require low maintenance. Free cracking is allowed in CRCP but the cracking pattern is controlled by the continuously longitudinal reinforcement. The problem is that in reality the crack pattern is not as desired. Distances between cracks are sometimes smaller, creating clusters of cracks. These clustered cracks can evolve over time, and, after many heavy axle load passages, lead to destructive punch-outs. To obtain a uniform crack pattern, the active crack control technique tries to force the cracks to originate in the young concrete at regular distances, perpendicular to the axis of the road. This is done by making some saw cuts in the new pavement, within 24 h after placement, along the side of the CRCP slab. This research study tries to find the optimal dimensions of the saw cuts which result into a uniform crack pattern. To do this, a numerical 2D model of a road segment is made with the finite element program Samcef Field. The length between the notches (= saw cuts) and the width and depth of the saw cuts are varied and deformations and stresses in the concrete and reinforcement are compared. The same is done for a 3D model which is generated based on the 2D model. The results from the parameter study show that the dimensions of the active crack control technique applied nowadays, i.e. saw cuts of 40 cm long, 4 cm deep, every 1.20 m, works properly.