The purpose of joint sealing concrete is to reduce infiltration of moisture and incompressible materials into joints for improved pavement performance. Infiltration of water through unsealed joints is the main source of surface water into the pavement structure. Moisture in the pavement foundation can allow loss of slab support from base and subgrade erosion and pumping, which causes concrete pavement distress. Sealing also can prevent incompressible materials from entering joints. Incompressible materials lock joints and create excessive stresses that may cause spalling, blowups, or shattering.

There have been considerable national debate and research efforts on the issues and cost-effectiveness of joint sealing and resealing. The department requires all joints to be sealed in concrete pavement per Item 360, “Concrete Pavement,” and the joint sealing standard.