An emerging trend for homebuilders is the construction of smaller homes with a few high-visibility upgrades that serve as selling features. Decorative stamped concrete is an upgrade that can be used for patios, driveways, sidewalks or even for interior floors. The textures available range from symmetrical brick or tile patterns to random designs simulating quarried stone, flagstone and cobblestone. With color added, which is almost always a part of the overall visual effect, the resulting surfaces give the appearance of decorative masonry, but at a lower cost.
GUIDANCE ON MATERIALS AND METHODS
Recommendations for achieving uniform, dependable results start with the mix. Small aggregate, 3/8-inch minus, and higher than normal sand content, as much as 70 or 80 percent, are needed so that coarse aggregate doesn't interfere with the stamping process. A minimum cement content of 6 or 6 « sacks per cubic yard is necessary because of the higher water demand of small-sized aggregate. Slump shouldn't exceed 4 inches and an air-entraining admixture should be used in all concrete that will be exposed to freezing and thawing cycles. Calcium chloride can cause color variations and its use is not recommended.
Integral color can be produced by batching a mineral pigment into the mix, but a dry-shake application is generally less expensive. A variegated effect can be achieved by combining two or more colored pigments to give a weathered appearance. This approach is especially helpful when tile patterns are used with a contrasting colored grout. One key to effective stamping is maintaining a constant depth of groove from the imprinting tool. For non-grouted applications, 1/4 inch is the maximum desirable depth because deeper penetration causes a tripping hazard. However, if the imprinting is too light, the desired appearance won't be produced.