- 1). Remove excess concrete from the foundation crack using a wire brush and a brick chisel. Use a shop-vac to vacuum the crack clean, and then wash the crack out with a water hose.
- 2). Mix two shovels of brick sand, three shovels of hydraulic cement, and 1 gallon of water in a 5-gallon bucket. Place the water in the bucket first, then add the sand and finally the cement mix. Use a drill and a paddle mixing bit--a 24-inch-long rod with blades on the end for mixing thinset--to stir the mixture. You may need to add more sand, cement, or water to make the mixture consistent with clay.
- 3). Pack the hydraulic cement into the crack using a small mason's trowel. Continue to pack the cement into the crack until it is full, and cut off the remaining materials using your trowel. The hydraulic cement will expand in the crack, thus bonding and sealing the crack completely. After 30 minutes, cut the expanded cement flush with the foundation wall using the trowel.
- 4). Fill the foundation crack using premixed epoxy cement. This is an alternative to hydraulic cement. The epoxy cement comes in a single syringe that separates the chemicals of the mixture until you press the plunger. Upon pressing, two chemicals leave the tube and mix at the application tip, thus beginning the catalyst for hardening the compound. Fill the crack full and even with the surface of the foundation crack. The mixture will not expand, so you will need to fill flush. After one hour, the epoxy should be hardened and will provide stability for your foundation for 10 to 20 years.