Superficial concrete damage may be unsightly, but will not affect the overall structural integrity of the slab if it is fixed promptly. Fixing concrete damage requires removing crumbling bits, filling cracks, and resurfacing as necessary.
Step 1: Remove any crumbling concrete with a cold chisel and ball peen hammer. Use a brush to remove any concrete dust.
Step 2: Enlarge any cracks to form an inverted V shape with a cold chisel. This will allow you to patch the crack, but prevent the concrete patch from popping out over time.
Step 3: Clean the crack with a brush and remove any dust with a shop vac.
Step 4: Apply a layer of concrete bonding solution to the surface that will be touched with the concrete patch.
Step 5: Mix enough patching concrete with water to fill all of the cracks. Pay particular attention to the ratio of water and concrete mix: too much water and the concrete will prematurely crumble.
Step 6: Force the patching concrete into the crack using a trowel. Feather the edges of the crack patch so it blends with the surrounding surface. Allow the crack to cure covered with plastic for several days.
TIP: Use a trowel, brush, or float to mimic the pattern of the surrounding concrete slab on the surface of the concrete patch.
Step 7: Examine the surface of the concrete. If it is in relatively good condition, you can stop with the repairs. If it is in somewhat poor condition, you should proceed and resurface the entire concrete slab.
Step 8: If the concrete slab has undefined edges, build formwork along the sides of the concrete slab that extend 2-4 inches above the existing surface. If you are resurfacing a slab that has a defined edge, such as a wall, remove any obstructions that would prevent you from adding a thin layer of concrete over the existing slab.
Step 9: Clean the concrete slab thoroughly. Apply a concrete bonding agent to the surface of the slab. Coat the inside surface of any formwork with a light film of vegetable oil.
Step 10: Mix self leveling compound according to the manufacturer’s instructions. You should mix enough self leveling compound to cover the surface of the concrete with at least 1 inch of concrete.
Step 11: Pour the self leveling compound onto the concrete slab. Pour it in several areas and spread it with a trowel. Over several minutes, if properly mixed, the self leveling compound will coat the concrete with a thin coat of concrete.
Step 12: After the concrete has cured for 12 hours, remove any formwork. Allow the concrete to cure for 24 hours before walking on it.
