The amount of work that must be put into the correction of surface defects will depend upon how carefully the formwork has been erected and removed and on whether or not the concrete has been placed correctly. Close attention to proper procedures for forming and concreting will unquestionably reduce the effort required for final finishing. If, however, after the formwork has been removed, you see that certain corrective steps must be taken, the suggestions in this article may be helpful. These include removing fins, mortar streaks and surface air holes; patching holes left by form bolts or ties; and correcting honeycombing.
Begin by cutting out the defective concrete as far back as the reinforcement, and if necessary behind it. Clean the exposed surface and wet it thoroughly. Then brush a cement and water grout well into it. Immediately afterward, fill up the entire area that has been cut away with a mortar of earth-dry consistency. Finish the surface with a wood float. Any desired board marks on the finished concrete surface can be carried across the patch by using the edge of a board to make a continuing impression in the mortar before it hardens. Other textures can be duplicated by pressing a piece of the forming material into the fresh patch.
All patches must be properly cured. Fog spray them with water immediately after the surface has hardened sufficiently or cover them with a wet cloth. Careful treatment during these finishing stages of producing an almost flawless concrete surface is just as important as it is throughout the entire construction job. For, in a sense, you are not patching but perfecting your work.