How Do You Fill Cracks in Hydraulic Cement in a Basement?

Remove any dirt and debris from the cracks with a wire brush. Reach into the cracks to the base and sweep out the material. Clean out the cracks with a mixture of dish washing detergent and water then rinse the solution from the crack with water only. Allow the cracks to dry out before continuing.

Attach plastic foam injection ports to the walls by covering the base of the ports with a thin layer of epoxy paste then pressing the ports onto the surface of each crack, straddling the center of the crack beneath the port. Use the wall thickness to determine the spacing between ports, adding an inch of space between the ports for each inch of wall depth. Spread the epoxy paste over the crack's length between ports with the putty knife to create a thin seal. Wait 45 minutes for the paste to cure to firmness.

Place the hose of a polyurethane foam-dispensing tool through the lowermost port into the crack in the wall. Press the tool’s trigger to inject the foam into the port, filling the area of the crack beneath with foam until you can see some of the foam entering the port opening above. Pull the hose from the port then plug it with the port cap.

Move to the next port upward and repeat the filling process. Continue to fill and plug each port until you fill the topmost port and plug it as well. Allow the foam to cure for 48 hours.

Remove the ports from the wall by striking them off with a hammer. Grind off the epoxy paste on the surface of the wall with a rotary sander until the surface is smooth and level with the surrounding cement.