Part 5. Repairs

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5.1 Routine inspection.
Floors subject to severe wear should be inspected frequently. Conditions the owner should note and consider for repair include slab deflection at joints (curling or faulting), cracks, debonded joint filler, chipped joints, gouges and popouts, erosion, and delaminations.

5.2 Slab deflection at joints.
Slab curling often results in a loss of sub-grade support beneath the slab edges at joints. On floors carrying vehicular traffic, the slab edge can deflect when a vehicle approaches the joint. The vehicle then impacts the edge of the adjacent slab. This not only interferes with vehicle operation, it can chip the slab edges. Tell owners to stabilize edge movement before repairing chipped joints or cracks. Repair contractors can treat slab movement by undersealing the joint. The high surface can then be ground down using a terrazzo-type grinder.

5.3 Cracks.
Explain that cracks thinner than a credit card and with no edge chipping usually can be left unrepaired, unless, as in the case of a food-processing plant, they can harbor bacteria and cause a health hazard. Wider cracks with no edge chipping can be repaired by pouring a medium-viscosity joint filler into the crack and shaving or grinding the surface flush after the filler cures. Cracks that have suffered edge chipping should be routed and filled with an appropriate filler.

5.4 Joint filler.
Fillers that have cracked or are not in complete contact with the concrete should be replaced. In some cases, additional filler should be poured into the joint. Tell the owner to follow the filler manufacturers instructions.

5.5 Joint chipping.
Tell the owner that repair of chipped joints can sometimes be done by in-house maintenance personnel, depending on the extent of the joint chipping. If large areas are chipped, a repair contractor will probably be needed. For small-scale repairs, some joint-filler manufacturers recommend sawcutting just outside the chipped areas to a depth of 1/2 to 1 inch then pouring a mixture of joint filler and sand into the opening. Openings wider than 11/4 inch require placing a thin board in the middle of the opening to form a new joint, reconstructing the slab edges with a rigid epoxy mortar, removing the board and filling the joint with an approved filler.

5.6 Gouges or popouts.
Although these surface defects may not get worse with age, they can create a hazard. Tell the owner to drill out any problem areas with a core drill to create perpendicular patch walls and then fill the void with a rigid epoxy mortar.

5.7 Differential settlement (faulting) at cracks or joints.
Explain that if vertical displacement interferes with operation of the facility, repair contractors can use slab-jacking procedures to raise or level the slab surface.

5.8 Special repairs.
For floors experiencing extensive problems such as the delamination of toppings or coatings or severe surface erosion, recommend that the owner use the services of a repair contractor.

Armand H. Gustaferro is a concrete consultant for The Consulting Engineers Group Inc., Mount Prospect, Ill. The firm investigates concrete problems and does structural engineering work.

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