A home is built on top of a foundation. When the ground underneath the foundation begins to settle, the foundation will often settle as well, creating cracks throughout. This is normal, and small movements happen at least every two to three years. When they appear, you can repair cracks as a weekend project.
Clean debris or loose foundation pieces out of the crack.
Mix the "S" mortar with the sand. Fill the bucket with water to one-quarter of its volume, or 1.25 gallons. Add the sand first, and then add the mortar. Make sure you add one part sand to two parts of mortar. Mix until it becomes slightly sticky, and can stay on the trowel without falling off.
Spray water onto the cracked area of the foundation. The mortar bonds more effectively to a wet area. The water will also help the mortar mix go into the crack and not sit outside of the crack.
Push the mortar mix into the crack with with trowel. With the back of the trowel, push the mortar into the crack.
Smooth the mortar until it is even with the foundation. Allow six to eight hours for the mortar to dry.