A quality sealant designed for outdoor concrete can help reduce water saturation and protect against salt damage. Applying a water-repellent sealant is a great solution for concrete peeling as it causes water and other liquids to bead off the surface, reducing water absorption by up to 95%. If you need an extra boost in strength and a decrease in water absorption, you can use silicate sealants in combination with water-repellent sealants. First apply a silicate densifier, followed by a silane siloxane water repellent sealant 5 to 7 days later.
Sealing is the best way to prevent husking due to moisture. For new concrete, apply a penetrating waterproofing sealant 28 days after the concrete is laid and every few years thereafter. Descaled concrete may appear as round or oval depressions along surfaces or joints. This type of damage is more common in cold climates when defrosting chemicals are applied or when seasonal freeze-thaw cycles damage concrete. To avoid stress cracking, make sure that the slab is built on a uniformly compacted and well-drained subgrade and that it is thick enough to withstand the type of use it will receive.
In residential concrete, 4 inches is the minimum thickness for walkways and patios. It usually takes 10 to 12 hours for the sealant to dry before you can walk on it, but it will continue to harden for up to 48 hours after application. Concrete sealed with a urethane coating should not be walked on (with the exception of a new layer), nor should it be driven or wet for at least 36-48 hours. If entrained air bubbles are not present near the concrete surface to act as an internal pressure relief system, hydraulic pressure can easily overcome the tensile strength of the surrounding cement paste. While sealing won't completely eliminate flaking, it will help reduce the chance of it occurring. During winter, water is absorbed into the concrete surface, where it freezes inside the pores.
The first and most common reason why concrete pots break is because the mixture contained too much water. Sealants are designed to reduce, but can never stop water absorption on the surface, meaning that exposed concrete remains at risk from salt, snow and ice damage. The crumbling of concrete is not only unsightly, but can also be a sign of serious damage under the structure. If you have new concrete that starts to show signs of deterioration such as cracking or peeling, there's likely a problem with pouring concrete. Over time, as internal pressure increases and decreases, the surface layer of concrete is stressed which leads to flaking.
To avoid spalling, focus on pouring concrete with just the right amount of water; keep the mixture as dry as possible as too much water can weaken concrete. The detachment occurs when the upper smooth surface of the concrete peels off and reveals the rough and rocky bottom layer. When temperatures drop below freezing point, moisture in the concrete tends to expand creating internal pressure. It's not uncommon for contractors and concrete builders to receive calls from customers asking why their concrete is peeling and chopping and how they can solve this problem. Work with your ready-mix concrete supplier to have a mix pool that covers all seasons and temperature variations.
