Concrete flaking is a common issue that can be caused by a variety of construction defects. Improper preparation of reinforcing steel, incompatible supporting metals, metal bars placed too close to the surface, stress fractures due to excessive weight, and insufficient concrete cover or poorly poured concrete can all lead to concrete flaking. In addition, the natural process of carbonation can cause water to seep into the concrete and corrode embedded elements, resulting in bulges and cracks on the surface. Poor quality steel can also contribute to chipping.
Air entrainment is a process that introduces small air bubbles into concrete by adding an air retention agent, a surfactant, or a portland cement that incorporates air into the mixture. To prevent new concrete from flaking, it is recommended to apply a penetrating waterproofing sealant 28 days after the concrete is laid and every few years thereafter. Surface cracking, also known as shrinkage cracking, and chipping due to poor design, placement and finishing of the mixture are not acceptable and can be avoided. The most common cause of chipping is corrosion of embedded steel reinforcing bars or steel sections.
Water seeps into the concrete and causes rebar and other elements embedded in the concrete to corrode, creating cracks and bumps on the surface. 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. Chipping is the peeling or detachment of small particles of cement paste from the portion close to the surface of the finished slab. To prevent chipping, it is important to be flexible with dosing rates as ambient and concrete temperatures change during placement.
An experienced professional in building and construction structures made of wood, concrete and steel can help with inspection, replacement, evaluation and forensic analysis.