Finished concrete is usually porous and can absorb rainwater, which can lead to peeling of the outer slabs when the water that is trapped in the concrete goes through multiple freezes and thaws. When water freezes, it expands by about 9%, creating tremendous pressure inside the slab. This phenomenon, also known as concrete flaking, is a common problem where part of the surface flakes off, breaks or splinters. Chipping is another term used to describe areas of concrete that have cracked and delaminated from the substrate.
There are several reasons why husking occurs, including freeze-thaw cycles, the expansive effects of the alkaline silica reaction, or exposure to fire. However, the most common cause of chipping is corrosion of embedded steel reinforcing bars or steel sections. Corrosive steel can expand up to ten times its original volume, putting stress on the surrounding concrete. If you tackle a chipping problem early on, it's easy to remedy it. After all, peeling begins as a purely cosmetic imperfection caused by cold weather.
When the temperature drops below the freezing point, the moisture in the concrete tends to expand, creating internal pressure. Over the course of a winter, or over the years, as internal pressure increases and decreases, the surface layer of concrete is stressed, which leads to flaking.
Concrete chippingis a common concern in older concrete structures. Alkalinity, a normal corrosion mechanism, causes the steel bar inserted into concrete to corrode over time.
The use of an appropriately qualified contractor is essential, as is diligent preparation of the substrate and the selection of a repair material compatible with host concrete. In certain cases when the concrete is new, a waterproofing sealant should be applied one month after the concrete is laid, as well as every few years after that. These variations in coverage recognize the fact that concrete is porous and that a greater concrete cover will significantly decrease the rate of corrosion of steel and subsequent degradation of concrete. The concrete that has been peeled must be rectified not only by repairing, but also by identifying and correcting the root cause. That said, although it can last for decades, concrete doesn't usually last without at least a modest amount of care and maintenance. This deficiency in concrete is solved by the use of reinforcing bars in structural concrete structures that have a high tensile strength to absorb the tensile force in the component. In most cases, the most exposed elements tend to deteriorate first; however, in steel corrosion, most corroded reinforcement is not visible and may take up to five or more years of active corrosion before cracks begin in concrete, at which point damage becomes visible. However, despite the best intentions, concrete patch repairs often fail prematurely due to ongoing corrosion around the periphery of repairs.
Over time, the expansive pressure of repeated freezing and thawing cycles can break the top surface of the concrete, leaving pit marks and exposing the coarse aggregate. Over time, due to the force applied by the freezing and thawing cycles together with the internal pressure of the expanded water, the top layer of the concrete tends to come off leaving marks of pits, concrete fragments or chips. Instead, it is probably due to poor installation techniques, poor curing, poor concrete mixing, or a combination of all three. As a result of this, the concrete surface peels off, fractures and ultimately breaks. The environment in which the concrete element is placed has a significant effect on its performance in relation to durability. To prevent concrete flaking, it's important to take preventive measures such as applying waterproofing sealants one month after laying down new concrete and every few years after that.
Additionally, using an appropriately qualified contractor for installation and selecting repair materials compatible with host concrete are essential steps for ensuring long-term durability.