Your local Sherwin Williams shop or sales representative for surface preparation recommendations. Or refer to the surface preparation video in this series. Once the surface is prepared, wet it. Mix one part Portland cement type 1 and one part fine sand by volume.
Add water until the mixture is the consistency of thick paint and brush it onto the wet concrete. Symptoms of concrete spalling are spalling, chipping and large chunks showing on the surface of the concrete, exposing the coarse, rocky concrete aggregate. These are the symptoms, but concrete spalling is more complex than just surface appearance. Concrete spalling is the result of a chemical and physical process that occurs within the concrete itself.
It is a relatively common problem with a number of causes ranging from how the concrete was mixed to environmental conditions. Below is a brief list of things that can cause concrete spalling. As we have seen, most concrete spalling occurs as a result of moisture entering the concrete, causing corrosion or swelling. In other cases, spalling occurs as a result of a poor method of mixing the concrete.
The most effective way to prevent concrete spalling is to use a waterproof sealant to prevent water from entering where it can cause damage. If your concrete has already succumbed to spalling, don't worry, you can repair it. The type of repair and the work involved depends on where the concrete spalling is, how deep it is, whether it is on a vertical or horizontal surface and whether there is any exposed rebar. If there is spalling in a basement wall or other vertical concrete surface, the repair can be a bit tricky.
To fix a concrete wall that is spalling, first cut into the concrete around the spalled area. Make the cut about three-eighths of an inch deep with a circular saw. Next, use a hammer and chisel to remove the concrete from the cut area. This step should expose the reinforced rebar.
Break up the concrete that is attached to the rebar. The bars are likely to be rusted. Remove the rust with a wire brush until a rust-free surface is exposed. To prevent further corrosion and spalling, paint the rebar with a rust-preventive paint.
The last step is to add the new concrete. Be sure to drive the concrete well into the hole so that no voids appear that could weaken the wall. Concrete spalling on a horizontal surface such as a driveway or pavement is not only an aesthetic problem, but also a safety hazard. Spalling on a concrete driveway or pavement may require a more comprehensive solution to ensure that it does not recur.
The most common method of repairing spalling on horizontal surfaces is to resurface and seal the surface with a coating solution. The advantage of using this method is that it not only repairs the spalled concrete, but prevents spalling problems from recurring. Some people mistakenly believe that it is necessary to completely remove the old concrete and re-pour new concrete to repair and prevent concrete spalling on driveways or pavements. Fortunately, repairing concrete spalling is often much easier and cheaper than that.
Concrete spalling is usually fixed with a cement-concrete resurfacer. A good concrete resurfacing product, such as Semco concrete resurfacer, can fill cracks, repair voids and resurface concrete without having to remove it. After the concrete is resurfaced, a waterproof concrete sealing system is recommended to prevent further spalling. Concrete resurfacing is used to repair and revitalise concrete surfaces that suffer from things as minor as staining and light corrosion due to the elements, to more structural problems such as spalling.
Concrete spalling can be partial or it can cover the entire surface. In cases of isolated spalling, a localised patching solution may be appropriate. In cases where spalling is more extensive, you may want to consider a resurfacing solution. Concrete resurfacing systems are designed to cover cracks, spalling and other imperfections with a durable, mechanically bonded microcement.
The concrete resurfacing product is sealed to ensure that spalling does not recur. The beauty of this option is also that you can incorporate decorative finishes depending on your beautification goals. For larger areas of pitting and spalling, we recommend using a 100poxy concrete patch with a sand aggregate. The silica sand is mixed with the epoxy to act as a filler.
Legacy Industrial's HD-110 concrete patch is a good example of this. There are several ways to fix spalled concrete. First, determine the severity of the problem. If spalling penetrates less than one-third the depth of the concrete, a patch or repair can correct the problems.
However, if the spalling is deeper, it is best to remove the concrete completely and lay a new foundation. When the temperature drops below freezing, moisture in the concrete tends to expand, creating internal pressure. Excess water can enter the concrete through cracks, or the concrete may have been incorrectly mixed when it was placed. Always pay special attention to the edges and corners of exposed concrete to ensure proper concrete cover as specified by the structural engineer or ACI.
Resurfacing material is simply spread over the existing, damaged concrete surface to create a fresh, flawless finish. Common mistakes are adding too much water to the mix, to make it easier to pour; spraying the concrete surface with water, to prolong the finishing time; and not curing the concrete properly after installation. That said, although it can last for decades, concrete does not usually last without a minimum of care and maintenance. Use this diagram to help you lay the concrete furring strips and concrete "framing strips" you will need to line your driveway.
For new concrete, apply a penetrating waterproofing sealer 28 days after concrete placement and every few years thereafter. There are a variety of products that can be used depending on the size of the repair you are making, the depth of the repair and, in some cases, the look you want to give it. Fortunately, most pitting and spalling in a garage can be easily repaired and is not as severe as that of concrete that is outdoors. All concrete can develop cracks and some spalling is inevitable, especially in colder climates and as the concrete ages.
What happens is that water settles on the garage floor and works its way into the capillaries of the concrete.