Surface voids, such as bug holes, form-tie holes, and honeycomb, are a fact of life in cast-in-place concrete construction. Depending on project specifications, they may need to be repaired. This article presents accepted techniques for repairing these common surface voids.

For bug holes, sack rubbing is an effective method. A good mix for sack rubbing contains 1 part portland cement, 1 ½ to 2 parts fine sand, and enough water to produce a consistency between that of thick paint and masonry mortar. Form-time holes, because of their high depth-to-width ratio, should be filled by dry packing. Dry pack is a stiff sand-cement mortar with a low water content, which minimizes drying shrinkage and improves durability.

Before repairing honeycomb and larger surface voids, remove loose material within the voids using a light chipping hammer. Then trowel repair material into the void or use a small pneumatic mortar gun to apply a grout similar to hand-applied dry pack.