Joint spalling is often a result of joint movement caused by curling. But there are other possible causes. In keyed construction joints, a keyway that’s too large may cause slab crack- ing above the female side of the key-way. If a crack-inducing plastic strip was used to form a control joint, the strip may not remain vertical. This creates a can-tilevered lip that later breaks off.
Atlas Restoration's Method for Repairing Joint Deterioration
To repair deteriorated joints, our crews make a sawcut at the edge of the deteriorated area, then remove all the cracked and crumbling concrete. Usually this is only a partial depth operation, but sometimes concrete is removed all the way to the sub-grade or base course.
The type of forklift traffic determines how strong the repair material has to be for a partial-depth repair. Forklifts with hard wheels instead of pneumatic tires are hard on joint edges. When the joint edge is exposed to this kind of abuse, your Atlas team uses a closed system epoxy mortar for repairs. Enough epoxy binder is added to a sand aggregate to completely fill air voids between particles. This material is usually installed to depths of 1⁄8 inch to 11⁄4 inches and gives excellent impact and wear resistance.
A groove cut in the partially hardened epoxy at the location of the old joint separates the edges of the abutting slabs so they move independently. Alternatively, the groove can be saw-cut after the epoxy has cured. If a groove isn’t cut, epoxy repair material binds slabs together, preventing joint movement. This can cause slab cracking parallel to the joint if there’s any further slab contraction or expansion.
In areas where concrete has failed to the full depth of the slab, we sawcut and remove the failed concrete. Then holes can be drilled in the exposed faces and dowel bars can be set in epoxy to transfer load. The repair is completed by using an accelerated strength gain concrete mix, so that floors can be ready for use within hours.