Can this be used to fill in cracks on cement siding planks?

We recommend either QUIKRETE® FastSet Repair Mortar (No. 1241) or QUIKRETE® Polymer Modified Structural Repair (No. 1241-25) to fill cracks that are at least 1/8 inch in width on cement siding. Both products are designed for making repairs to small areas (less than 2 square feet in area). Please note that the repair area must be sound, clean, unsealed/uncoated., and free of dirt, dust, loose debris, and any other potential bond breakers. When making repairs, getting a good color match can be difficult – we always recommend trialing the repair material in a small, inconspicuous area first and waiting 24 hours to ensure that the appearance, including color, is acceptable.