Question: My builder is trying to persuade me to use colored stamped concrete for my front walk. I'm worried that the textured finish will not last.
Is stamped concrete as good as regular concrete? What can be done to ensure a long-lasting job? Is it possible to colorize regular concrete after it is poured?
Answer: I think I can significantly reduce your anxiety level about pattern-stamped concrete. It is a fantastic technique to improve the appearance of otherwise bland concrete.
Concrete in and of itself is a premier building material. Adding color and texture to it simply enhances its appeal.
Pattern stamping is not really new. It has been done for years in one form or another.
As a child I often saw the name stamp of the contractor who installed the sidewalks in my neighborhood. Steep concrete roadways were often stamped with horizontal lines to increase traction.
The pattern-stamped residential concrete your builder is using has been around for almost four decades.
The stamping processes available today can create more than 90 different patterns. They include a wood boardwalk look, slate, cobblestone, brick, flagstone and ceramic tile. When the installer blends different colors with the wet cement, the effect is dramatic.
If you have visited theme parks or other attractions, there is a good chance that you have walked across stamped concrete thinking it was a natural stone product. Contractors who use molds and pattern stamps can create unbelievable results.
There is no reason why your front walk shouldn't last for many years. As long as your contractor follows all of the known industry standards for pouring cement, your stamped walk should outlast you.
I would suggest that you install half-inch steel reinforcing bars on 24-inch centers in both directions of your walkway. Be sure that this steel ends up in the middle of the 4-inch-thick sidewalk. Make sure also that the concrete is ordered with a minimum compressive strength of 4,000 pounds a square inch.
If you choose to install stamped concrete in your driveway, insist on a minimum thickness of 6 inches. Be sure that the cement is cured after it is installed.
Cement shrinks as it dries. This shrinkage usually amounts to 1/16 inch for every 10 feet you pour. This shrinkage produces internal stresses within the concrete.
To prevent random cracking you must install control joints. These joints are saw-cut lines often created the day after the pour. They should be cut to a minimum depth of a quarter of the thickness of the slab.
It is possible to colorize an existing slab. Various chemical concrete stains can be used. Often these contain muriatic acid and metallic salt compounds. Some are water-based products.
The acid products etch the concrete, allowing the stain to penetrate. Because of differences in the texture and makeup of the existing concrete, it can be difficult to maintain uniform coloration.
If you choose to stain existing concrete, you must pay close attention to manufacturer's instructions. Rich colors are possible, but you will need to practice to achieve them on a consistent basis.
Send for Builder Bulletin No. 130 illustrating 25 of the most popular stamped concrete patterns, literature sources, detailed installation techniques and stamped concrete and stain companies. Send $3 and your name and address to Tim Carter, c/o St. Petersburg Times, P.O. Box 36352, Cincinnati, OH 45236-0352.
Tim Carter is a licensed contractor. Got a question for him? Call toll free from 10 a.m. to noon today at (888) 737-1450 on his radio call-in show (not broadcast in the Tampa Bay area). Visit his Web site at http://www.askthebuilder.com.