Large and small holes are treated differently when repairing concrete. The best product for filling in smaller holes (less than 1/2″ deep) is vinyl-reinforced concrete patcher, which is often sold in convenient quart of gallon containers of dry powder. Reinforced repair products should be applied only in layers that are 1/2″ thick or less.
For deeper holes, use sand-mix concrete with an acrylic or latex fortifier, which can be applied in layers up to 2″ thick. This material is sold in 60- or 80-pound bags of dry mix.
Patches in concrete will be more effective if you create clean, backward-angled cuts around the damaged area, to create a stronger bond. For extensive cutting of damaged concrete, it’s best to score the concrete first with a circular saw equipped with a masonry blade. Use a chisel and maul to complete the job.
Tools & Materials
Trowels; Drill with masonry-grinding disc; Circular saw with masonry-cutting blade; Cold chisel; Hand maul; Paint brush; Screed board; Float; Scrap lumber; Vegetable oil or commercial release agent; Hydraulic cement; Latex bonding agent; Vinyl-reinforced patching compound; Sand-mix; Concrete fortifier; Plastic sheeting.
Use hydraulic cement or quick-setting cement for repairing holes and chip-outs in vertical surfaces. Because they set up in just a few minutes, these products can be shaped to fill holes without the need for forms. If the structure is exposed constantly to moisture, use hydraulic cement.
How to Patch Large Areas
Step1: Mark straight cutting lines around the damaged area, then cut with a circular saw equipped with a masonry-cutting blade. Set the foot of the saw so the cut bevels away from the damage at a 15° angle. Chisel out any remaining concrete within the repair area. Tip: Set the foot of the saw on a thin board to protect it from the concrete.
Step3: Smooth and feather the repair with a float until the repair is even with the surrounding surface.
How to Patch Small Holes
Step1: Cut out around the damaged area with a masonry-grinding disc mounted on a portable drill (or use a hammer and stone chisel). The cuts should bevel about 15° away from the center of the damaged area. Chisel out any loose concrete within the repair area. Always wear gloves and eye protection.
Step2: Apply a thin layer of latex bonding agent. The adhesive will bond with the damaged surface and create a strong bonding surface for the patching compound. Wait until the latex bonding agent is tacky (no more than 30 minutes) before proceeding to the next step.
Step3: Fill the damaged area with vinyl-reinforced patching compound, applied in 1/4″ to 1/2″ layers. Wait about 30 minutes between applications. Add layers of the mixture until the compound is packed to just above surface level. Feather the edges smooth, cover the repair with plastic, and protect from traffic for at least one week.