Concrete driveways may be strong and long-lasting, but they can develop fine cracks and chips due to weather, an unstable foundation and poor quality concrete. If your driveway has excessive chips that detract from the overall beauty of your front yard, skim coating it will significantly improve the appearance. Pouring a thin, new layer of concrete over the old surface will smooth out any chips or pits and give you the opportunity to add color.
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Benefits of a Concrete Top Coat
Skim coating concrete gives it a new finish about 1/4-inch thick. Unlike other types of decorative refinishing options, like stamping concrete or exposing decorative aggregate, skim coating is within the capability of beginner and experienced do-it-yourselfers alike. It also barely raises the level of the driveway, so it won't throw off the alignment with the driveway surface and the garage or walkways. The materials and tools required are inexpensive, and the whole process can be completed in about a day, depending on the length of the driveway.
Is a Concrete Skim Coat the Solution?
If the chips in your driveway formed over time, skim coating and sealing the surface is a simple cosmetic solution. For a new driveway, excessive chipping can indicate that the slab itself is weak. Causes for weak concrete include drying out the surface too quickly or low quality concrete. Skim coating weak concrete is only a temporary fix. Another option is to lay a thicker overlay and slow-dry the new surface. To slow-dry, cover the driveway with moist, breathable material. Keep the material wet to provide additional moisture for the concrete to absorb.
If your driveway is chipping because the concrete is moving or being lifted up, skim coating won't solve the problem. You should consult a concrete professional who can advise the best way to fix the issues.
Preparing the Concrete Surface
The chipped surface must be properly prepared before applying the skim coat. All dirt, debris and stains should be removed because they can weaken the bond between the new and old concrete. Remove any traces of sealants with a chemical stripper. Once all solutions are rinsed away, patch any cracks or pits with vinyl patch compound or they will show through. Finally, use a sandblaster or grinder to even out the surface and rough it up.
Applying the Concrete Skim Coat
Skim coating concrete entails applying two layers of finish. The first layer is Thin Finish and it should be 1/8 inch thick. If you're using an acid stain, add a base color to this mix. Spray the driveway with a hose so the finish will form a strong bond with the concrete. Spread the Thin Finish with a squeegee and wait for it to dry. The second coat of Thin Finish is mixed with a quart less water than the first coat for every 55 pound bag of mix, and then add the base color. Use a flat metal trowel to spread the thicker mix into an 1/8-inch thick layer. After the finish dries for a day, apply the acid stain if desired.