Things You'll Need
1-inch plastic putty knife
Concrete block walls provide excellent structural and security barriers for your home. Block walls also provide a solid barrier against the elements. Attaching items to the inside or outside of your block wall requires making a hole in the concrete to install a screw or bolt. The hole is then sealed around the fastener to prevent leaks. When these screws are removed, you must cover the holes in order to maintain the watertight integrity of your structure.
Mix a handful of dry Portland cement mix in a bucket with enough water to obtain an oatmeal-like thickness. Stir the ingredients with your putty knife. Allow the mixture to begin to cure for 5 minutes in the bucket.
Grab a spoonful of the cement mix in your hands. Roll the mixture between your palms to form a ball. Push the ball gently into each screw hole.
Wipe the surface of each hole smooth with your fingertip. Allow the cement to dry completely.
Scoop a small bit of cement onto the tip of your putty knife. Press the concrete into the gaps in the screw holes where the original patch shrunk during the drying process. Allow the cement to dry and repeat as necessary to get the patch flush with the face of the wall.