It may be inaccurate to apply the term "maintenance" to such permanent installations as masonry projects, but there are times when some touch-up work is in order. The most common fault that will appear in concrete - is, despite the most careful preparation of mix, installation and curing - is a crack.

If this is due to a poor subbase the crack can become quite serious, especially if uneven settling causes a portion of the slab to sink below the grade level of adjacent areas. Many times it is necessary to crack up the nuisance area, remove the old concrete and repour. But this sort of major repair job will become necessary only if you neglect the procedures outlined or skip some of the steps in an effort to hurry the job.

Most of the time the crack will be isolated - across a corner or into an expansion or contraction joint. When it is too bad to walk on or too unsightly to tolerate, it can be easily repaired. The first step is to remove the bad concrete.

If the crack is wide and deep you can often get a pry bar under the piece and lift it right off the sub-base. If the repair area is in the center of a slab or walk, use a wide chisel and hammer to remove the bad material. Be sure all edges are clean even if you have to chip off a little concrete from adjacent good areas.

Clean the section thoroughly to remove all dirt, dust and any foreign matter. Oil or grease will make it difficult for the new patch to adhere to existing concrete; if any is present, remove it by washing with a solution of 8 oz. of tri-sodium-phosphate in 1 gal. of hot water. Scrub the surface thoroughly with the solution and rinse with clean water.

Allow excess moisture to drain off and paint the area with pure cement adhesive. Coat the bottom of the cavity as well as all edges. When this coating is sticky to the touch it is ready to take the pour.

Cement adhesive should also be used in the mix you make for the repair job. Fifteen oz. of dry mix cement adhesive product, an equal amount of water and a 60 lb. sack of concrete makes a good repair substance. The ingredients should be thoroughly mixed and then mixed again with enough additional water to get a good flowing concrete. Cement adhesive products may differ, so be sure to read labels carefully and follow directions.

Apply the mix to the prepared, tacky surface and work it in just enough to fill all crevices. Finish with float or trowel to match adjacent areas. As soon as the patch has hardened on the surface so it won't mar, sprinkle it with water and cover with paper or canvas or an old burlap sack and keep the surface damp for at least three days. If the weather is hot or if the repair job will be exposed to bright sunlight, it is a good idea to cover and keep moist for an even longer period.

Caulking Small Cracks

Where the size or location of the crack does not justify a complete repair, it is usually advisable to seal it with a suitable caulking material to prevent it from collecting water.

In brickwork or concrete block, cracks may occur at door and window openings. They can be caused by settling of the house and/or foundation, or even by moisture in a joint which, in freezing weather, expands the joint and forms a crack. Repair is simple - just a matter of cleaning the crack and refilling it with fresh mortar.

With a little time and effort, masonry can be maintained almost perfectly for a very long time.