: For deep or vertical cracks, use a diamond blade or a grinder to slightly widen them; this creates more surface area for the filler to bond. 2. Clean and Sand A smooth, dust-free surface is essential for adhesion:

: For missing corners or deep pits, use a prepared concrete patch or multi-purpose repair mortar . Push the material deep into the cavities with the corner of a trowel.

: Use rough-grit sandpaper to even out rough patches and ensure the edges of the repair area are flush with the original sill.