Descaling can ruin the structural integrity of concrete and compromise any load borne.
Chippingis a 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. Most engineers and architects have probably observed some degree of chipping on the surface of a reinforced concrete structure or element. Descaling typically occurs as a result of stresses caused by differential movement of construction materials that are in contact with each other, or due to a progressive deterioration mechanism such as corrosion. As an 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. However, this condition occurs close to ground level and does not present a potential danger to aviation safety.
Concrete peeling is a common concern in older concrete structures. Alkalinity, a normal corrosion mechanism, causes the steel bar inserted into concrete to corrode over time. Descaling can be inconsequential, that is, a purely aesthetic problem, or it can cause serious structural damage that requires costly remediation work. Concrete is a versatile material in construction. This common material is used for walls, floors, foundations, pillars, steps, balconies, roofs and many other similar structural building components.
Concrete 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 undiagnosed or treated, peeling of concrete can lead to hazardous conditions. 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.
In this situation, a piece of concrete that falls off the edge of the building will gain speed as it falls and, because such a building is typically surrounded by streets and public spaces, it is very likely to fall into a public space with a lot of occupancy or traffic. Salt chlorides (in coastal environments) and water (rain) will contribute to steel corrosion and concrete flaking. 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. Both water intrusion and chloride intrusion promote corrosion of the reinforcing bars, resulting in an overall volumetric gain of the reinforced concrete element and thus exerts pressure on the concrete cover, eventually leading to flaking. Bricks deteriorate through peeling as a result of moisture penetration, which will eventually lead to cracking. After the evaluation, it was determined that descaling was the result of corrosion of reinforcing steel, which in turn was attributed to the lack of an adequate concrete cover.
Although rust is a long process, the owner of the property or the management body will not underestimate the consequences of the peeling of concrete and will leave the defect unattended for a long time. Since corrosion is a slow process, the property owner or management company should not underestimate the seriousness of concrete peeling and neglect the problem for an extended period of time. Concrete peeling refers to the common structural defect in which surface concrete (“concrete cover”) falls locally and exposes the steel rebar (“rebar”) underneath. Chipping can have far-reaching consequences in terms of health and safety, structural integrity and asset value. Concrete peeling repairs are carried out by cutting the delaminated concrete, replacing or cleaning the steel reinforcement, priming the steel plus the surrounding concrete, and then repairing with a high-quality polymer-modified concrete repair mortar to the original profile; this will restore structure integrity.
Chipping is often caused by poor installation, poor maintenance, poor repairs or environmental factors. Conditions of insufficient coverage were widespread throughout the building's exterior with potential safety risks identified on many balconies and two locations identified as having immediate safety concerns requiring rapid removal of peeling and loose concrete. In addition, delamination and descaling require greater maintenance subsequently higher maintenance costs and may result in decreased service life for these components. Over time it is important to monitor whether restored concrete is rusting again as well as recognize any other new design defects in need for corrective action.