Concrete expansion joints are placed in concrete slabs in order to allow for trouble-free expansion and contraction of the concrete during temperature changes. By placing expansion joints when laying concrete, you prevent the cracks and breaks that may otherwise occur in the concrete if the safety margin of the joints were not added. Unfortunately, either through a mistake when cutting the joints, or simply with the passage of time, these joints may become damaged. When the joints have grown wide over time, pulled away from adjoining structures, or developed cracks, the joints can be repaired using a joint sealer, preventing the spread of damage to the rest of the concrete, or the adjoining structure.
During the first stages of settling, concrete tends to shrink in volume. This shrinkage can cause surfaces to become unstable and cracks to form around the building’s most structurally weak areas — most notably the joints.
Joints exist where one concrete slab meets another, and usually require the most ongoing maintenance. Their edges often become damaged as a result of the high amount of traffic they experience on a daily basis.
The cracks that form on these joints, if ignored, can lead to further structural weakness, and eventually to crumbling concrete.
Concrete floor joints are designed and positioned to allow movement in concrete floors, without restraining movement as that could lead to random cracking. Joint sealant should be rigid enough to provide support and protection to the concrete arrisses, but it must also accommodate the anticipated movement in the floor whilst remaining bonded to at least one face of the joint.
The four steps that must be followed to repair joint damage include: