Things You'll Need
High-strength hydraulic concrete
Erosion caused by plant roots or water drainage from the roof or the surrounding soil will often attack the corner of a structure's foundation. Sometimes the adjoining vertical walls of the home or building will also suffer damage. A building owner needs to repair this type of damage as soon as possible to avoid further, often more serious, damage to the structure.
Dig and chop out any plant roots growing near the foundation. Prevent further water erosion by re-routing the flow of water. Fill in any depressed or sunken ground areas near the foundation's area of erosion. Ensure that all water flow is directed away from the structure's walls and foundation.
Dig up and remove all soil and other materials from the eroded area. Store this soil for later replacement after the repairs are completed. Be sure to remove all soil from at least 4 inches beyond and underneath any visible damaged foundation and/or any vertical wall surfaces.
Brush clean the exposed foundation concrete or stone surfaces and edges, making sure all dust, grease, oil and other loose particles are removed from the exposed foundation and wall areas. Make sure the ground surface underneath the exposed foundation is level and compacted.
Use a cold chisel and heavy hammer to create undercut notches (the inside of the notch is larger than the outside) on the existing foundation edge surface that will be joined by the repair concrete filler so that as the hydraulic cement cures, it will expand and become "keyed," or locked, into place and adhere to the existing concrete foundation.
Erect plywood retaining boards in an upright position to create a new corner mold brace for the forthcoming wet concrete repair material. Brace the plywood retaining boards with appropriate-length wood boards.
Remove all materials such as carpet, wall-board, plaster and dirt from the cleaned, exposed foundation.
Spray water on all surfaces that will receive the concrete filler.
While wearing safety goggles and rubber gloves, mix the high-strength hydraulic concrete per directions.
Pour the mix into the prepared area until the volume is filled to within ½ inch from the top.
Trowel the surface to a level grade. Follow the drying instructions from the concrete manufacturer.
After the first fill is cured, fill the remaining ½ inch with additional prepared concrete mix and trowel to a level finish to the rest of the foundation surface. Follow the manufacturer's curing instructions.
Seal the finished repair to the foundation with a concrete sealant, both inside and around the outside edges.
Replace the previously dug soil back around the repaired foundation.
Be sure to repair any damage to the vertical walls above the foundation corner. Double-check after the repair is complete to ensure that all rainwater or landscape water will flow away from the structure.