Concrete that has cracked or crumbled during the winter should be repaired early to help prevent additional damage.
Do-it-yourselfers have a choice of several well-tested repair products and a new product that simplifies crack-patching.
The new product is a liquid concrete sealant sold in plastic squeeze bottles under a variety of brand names, including Sure-Fix, Four Seasons and Set. The bottles have tapered nozzles to fit into narrow cracks, but these can be trimmed to increase the flow of patcher.
The polymer-based patching liquids cure to a gray color that matches well with some old concrete. Manufacturers say the cured patcher retains some flexibility, which improves adhesion and helps prevent cracking of the patch.
I tried Four Seasons in some patio cracks and found it easy to use and free of much of the mess that accompanies some concrete patching. The patches appear solid, but I can't vouch for long-term results.
Four Seasons is made by Brewer Co. of Cincinnati, Ohio; a quart bottle costs about $8. Basically similar products are made by W. R. Bonsal Co. of Charlotte, N.C., (Pour-n-Patch); Set Consumer products of Cleveland, Ohio (Set); and other manufacturers. You'll find them at home centers and hardware stores.
When using liquid or other concrete patchers, wear goggles and gloves. Check packages for specific instructions and limitations. Tools can be cleaned with water.
In general, liquid patchers can be used on cracks up to a 1/2 -inch wide. Clean the crack with a vacuum or brush before patching. Deep cracks should be filled with sand to within about a 1/2 -inch of the surface. Apply the patcher in layers about a 1/4 -inch thick, allowing overnight curing between layers. Smooth the final layer with a small trowel.
Here are some guidelines for do-it-yourselfers who prefer more conventional concrete-repair products:
Patching cements of various types are sold in cans, small plastic tubs, caulking-gun cartridges and bags. Fairly expensive, they should generally be used for smaller repairs, such as cracks up to about a 1/2 -inch wide, and shallow, crumbled areas.
Most patching cements are dry powders that are mixed immediately before use with water and/or other additives to a consistency of thick batter. Some contain materials such as latex or vinyl for better spreadability and adhesion.
Always read directions before use.
Some patching cements cure very quickly, so the repair area should be cleaned and other preparations made before mixing. Application is usually best made with a small trowel. Edges can be feathered or thinned with a damp paintbrush.
Sand mix is a relatively inexpensive mixture of portland cement and sand sold in bags weighing up to about 80 pounds. It can be used to repair large cracks or sizable crumbled areas. Use sand mix for repairs requiring thicknesses of more than a 1/2 -inch but less than 2 inches.
Blended with water immediately before use, sand mix has more working time than patching cements. A stiff mixture is best. Clean and dampen repair surfaces before applying.
Gravel mix or concrete mix is another relatively inexpensive blend sold in large bags. Besides cement and sand, it contains an aggregate of fine gravel or stones that add strength and cohesion. Use gravel mix when repairs require a thickness of 2 inches or more.
Gravel mix is prepared like sand mix. If large areas are being repaired, the mixed batter can be poured or shoveled into place, then worked and smoothed with trowels.