Is Concrete Descaling Structurally Dangerous?

Descaling can have a detrimental effect on reinforced concrete structures & elements; learn about its causes & preventive measures for repair.

Is Concrete Descaling Structurally Dangerous?

Descaling can have a detrimental effect on the structural integrity of concrete and any load it bears. Most engineers and architects have likely seen some degree of chipping on the surface of a reinforced concrete structure or element. This is usually caused by stresses due to differential movement of construction materials that are in contact with each other, or due to a progressive deterioration mechanism such as corrosion. For example, the peeling of concrete from the corner of a foundation is common due to the different expansion and contraction characteristics of many building sheets compared to foundation concrete.

Concrete is a widely used material in construction, used for walls, floors, foundations, pillars, steps, balconies, roofs and many other similar structural building components. It requires reinforcement to function properly in a structural capacity. Most concrete structures contain reinforcement. Corrosion of steel reinforcement embedded in concrete can cause flaking of concrete.

If left untreated, peeling of concrete can lead to hazardous conditions. It is important to understand the basic causes that lead to concrete flaking and other forms of material failure; once these causes are identified and understood, there are preventive ways to repair concrete and install protective systems to extend service life. One of the many reasons why concrete flaking occurs is due to the natural process called carbonation. Water seeps into concrete and causes other elements, especially reinforcing bars embedded in concrete, to corrode. This creates bulges and cracks on the surface of the concrete.

Steel reinforcing bars are often used in concrete to provide durability. In addition, poor quality steel can lead to chipping. While the problem may initially seem like an aesthetic concern, the concrete system is beginning a process of deterioration, resulting in material failure. Pouring it in an ideal climate, using high-quality concrete, controlling environmental factors as much as possible, and sealing it periodically can help prevent cracks and chips and keep the concrete in the best condition for as long as possible. During fire-fighting operations, water poured onto the heated concrete surface also causes flaking. Greater coverage is required for conditions of greater exposure, such as when the concrete element is thrown into the ground and permanently exposed to it, as opposed to being protected by a roof or other covering.

Concrete peeling is one of the most common problems in which part of the surface breaks, peels and splinters. Sometimes the corrosion of steel in a concrete structure is too severe for treatment, since the scope of partial replacement and on-site repairs may be close to the cost of complete replacement. The descaling of concrete not only degrades the visual quality of the building, but also has a long-term effect on the efficiency and integrity of the structure. The driveway is exposed to cold weather and developed minor etching, cracking and chipping within a year. Corrosive steel can expand up to ten times its original volume, putting stress on the surrounding concrete.

This lack of protection resulted in corrosion of reinforcing steel and localized scaling at multiple locations throughout the exterior of the structure where the roof was deficient. Steel bars rust and increase in thickness as carbon dioxide corrodes concrete and mixes with water. Unfortunately, an adhesive plaster approach is often taken to repair peeling structures, without treating the underlying causes. It's not uncommon for concrete builders and contractors to receive calls from customers asking why their concrete is pitted and peeled. Beyond the obvious aesthetic problems, a reduction in cross-sectional area due to flaking and delamination is synonymous with a weakened concrete section. Descaling can be dangerous if left untreated; it can compromise any load borne by a structure or element made from reinforced concrete.