Repairing & Sealing Horizontal And Vertical Expansion Joints
Expansion joints can be the joints between walls and concrete slabs. Concrete Expansion Joints are cuts in concrete slabs that go completely through the slab to the base material. The purpose of an expansion joint is to allow the concrete slab to expand and contract with temperature changes without cracking the slab. Concrete expansion joints must be sealed with a flexible sealant or an expansion joint strip, to prevent water from penetrating the joint and deteriorating the sub base. As with any concrete repair, proper attention to joint preparation is essential to achieving a successful result. Expansion joints should be swept out to ensure that any pebbles, dirt or loose debris are removed.
Self-Leveling Polyurethane Sealant is a highly fluid and flexible sealant that will stretch up to 800 percent without failing. This allows for ground movement and expansion and contraction from temperature change. For joints over 1/4 inch, Backer Rod, which is a foam rope, should be placed in the expansion joint before applying the sealant. The Backer Rod should be pressed into the joint allowing a sealant depth of between 1/8 inch and 1/2 inch. Polyurethane sealants work best when they are bonded only to the inside edges of the crack or joint.