What Is Concrete Spalling?
Spalling issues in concrete can have an adverse effect on the adhesion of concrete coatings. Concrete Spalling is when water enters the concrete and forces the surface to peel, pop up or flake off due to the expansion and contraction of the water within the concrete. This usually happens because there is moisture in the concrete. This can be common in below grade basements, wetter climates in the country or were the ground water table is higher. Excess moisture can arise from irrigation or sprinkler system also. A common issue in older slabs is no moisture vapor sheeting was applied under the concrete slab.
It’s important to identify the potential for this to happen so that we can explain the process to a customer, and avoid it happening, prior to installing an Epoxy floor coating.
Spalling can also occur when water freezes and thaws in the colder months, causing the concrete to expand and contract. That continuous cycle breaks down the concrete and it can fall apart. Chemicals such as the sodium chloride that is used to deice the roads in the winter months can also break down the concrete leaving the surface pitted and deteriorating. Another form of spalling can occur when exposure to salt in the air near the ocean breaks down the concrete. Obviously, we don’t have that problem here, but it is interesting to know. But, I will say this, we did a garage floor in McCall Idaho in 2019.  The entrance to the garage floor had a terrible concrete spalling problem.  All the way across the entrance into the garage and about 18″ into the garage floor, the cement had terrible spalling going on.  This concrete spalling was caused by the roads being salted and the cars tires carrying the salt into the garage. As the snow on the tires melted, the water dissolved the salt and then the salt ate away the cement.  We cleaned out the concrete spalling area and then patched it with our cement patching product.  At that time we were able to coat it with our Epoxy.  The floor was fixed permanently and it came out looking beautiful.
Regardless of the reason for the concrete spalling, it’s critical to explain it clearly and concisely to the customer before applying the epoxy coating. I have only seen concrete spalling occur here in the Treasure Valley once and that was a much older house right next to the Boise river. We were able to do the job by applying a moister sealer on the cement before we applied the Epoxy.  So, when bidding on a job it’s important to recognize any issues with the concrete surface and explain the potential problems to the customer and how we can solve them before applying our floor coating.