What is the main reason for cracking and seating or rubblizing PCC slabs?

The main reason for cracking and seating or rubblizing PCC (Portland Cement Concrete) slabs is to eliminate reflective cracking in the HMA (Hot Mix Asphalt) at the joints. When new HMA is placed over an existing PCC surface, any joints or cracks in the PCC can reflect through the new asphalt layer, leading to premature distress and failure in the asphalt. By cracking and seating or rubblizing the PCC, the slabs are broken into smaller pieces that can better conform to the surface beneath the new asphalt layer. This treatment helps to distribute loads more evenly and reduces the likelihood of reflective cracking, which is a significant issue that can compromise the longevity and performance of the asphalt overlay.

While improving stability beneath the slab might contribute to overall performance, it is not the primary focus of the cracking and seating or rubblizing process. Similarly, removing the reinforcing steel is not the goal, as the reinforcement is usually left in place during these treatments. Therefore, the effective prevention of reflective cracking is the key reason for employing these methods on PCC slabs prior to paving with HMA.