Joint Sealing on concrete slabs

Joint sealing is the process of cleaning and sealing or resealing PCC joints. This technique is used to stop surface water infiltration into the pavement foundation and to stop the accumulation of debris in the joints. Water infiltration results in weakened support and eventual pumping, corner breaks, and slab shattering. Accumulation of debris in joints leads to spalling of the concrete and is a source of foreign object damage to aircraft engines.

The technique consists of the following steps:

  1. Remove the old joint material with a joint cutter. High pressure water may be used as an alternative. Removal depth is typically twice the final width of the joint.

  2. Old cold-applied material may be removed by hand if they are short in length.

  3. Airblow the joint and vacuum the debris. As a minimum, blow debris away from the joint and sweep it up.

  4. Sawing or refacing (as required). The joint must be refaced if the sides are not vertical or if you need to widen the joint to a specified width and depth for proper shape factor and proper sealant bonding. Joints that are severely spalled should be reconstructed using partial-depth patch procedures.

  5. Following refacing, clean by sand- or water-blasting to remove all debris from joint. As a minimum, thoroughly airblow the joint and vacuum the debris.

  6. Install a backer rod or separating medium at the proper depth, ensuring that the material is not twisted or stretched.

  7. Apply the primer on the edges of the joint, in order to achieve a perfect adhesion with the sealant.

  8. Apply the proper sealant using a pressure injection wand or a sealant gun. The sealant must be applied from the bottom up. Don’t overfill the joint: it should be 3-4 mm below the joint surface to avoid extrusion.