What is the most common cause for joints to open up during paving?

The most common cause for joints to open up during paving is insufficient material at the longitudinal joint. Properly placing and compacting the asphalt at the joints is crucial to maintain the integrity of the paved surface. When there isn't enough material at the joint, it can lead to gaps or openings as the asphalt cools and settles, resulting in an inadequate bond between adjacent lanes. This can compromise the durability of the pavement and lead to further issues such as water infiltration and degradation over time.

By ensuring there is an appropriate amount of material at the joint, inspectors help to facilitate proper compaction and bonding, mitigating the risk of joints opening and improving the overall performance of the pavement.