Descaling is the deterioration of steel-reinforced concrete and is characterized by the appearance of cracks and red rust. In severe cases, the concrete sections are completely detached from the reinforcing steel bar (known as “rebar”), exposing the rebar to the elements. The symptoms of peeling concrete are flaking, chipping, and large pieces that you see missing from the concrete surface, exposing the aggregate of coarse, rocky concrete. Those are the symptoms, but the peeling of concrete is a bit more complex than the appearance at the surface level.
The descaling of concrete is the result of chemical and physical processes that occur within the concrete itself. It is a relatively common problem with a number of causes ranging from the way concrete was mixed to environmental conditions. Peeling concrete is a common problem where part of the surface flakes off, breaks or splinters. Also known as flaking, it is the result of a weak surface that is susceptible to damage.
When steel is cast into concrete, naturally high alkalinity helps protect embedded steel from corrosion. However, the protection afforded by high alkalinity can be compromised by the ingress of acidic atmospheric gases, a process commonly known as carbonation, or by the presence of salts in concrete, typically from marine environments or by the use of de-icing salts. Combine these contaminants with oxygen and water and we have the key ingredients for corrosion. The reason why some concrete structures exhibit widespread flaking, while others appear to be in good condition is due to a combination of age, maintenance, concrete quality, concrete cover depth and local environmental conditions.
It's not uncommon for contractors and concrete builders to receive calls from customers asking why their concrete is peeling and chopping and how the problem can be solved. Descaled concrete may resemble round or oval depressions along surfaces. Descaling tends to be more common in cold climates when defrosting chemicals are applied or when seasonal freeze-thaw cycles damage concrete. Beyond the obvious aesthetic problems, a reduction in cross-sectional area due to flaking and delamination is synonymous with a weakened concrete section.
Delamination and chipping of a concrete member are undesirable conditions; they not only represent a potential impact hazard in the scenario in which chipped concrete falls and hits a person, but also reduces the cross-sectional area of the concrete member and decreases its ability to transport safely imposed burdens. The descaling of the concrete normally begins when the steel reinforcement embedded within the concrete member is oxidized. And, if you have chipping, have it treated as soon as possible to maintain the structural integrity of the concrete as much as possible. The remedies for chipping vary depending on the severity of the problem, the type and location of the concrete structure and other factors.
Over the years, this freeze-thaw cycle can weaken and crack the top layer of concrete, resulting in ugly notches and exposed aggregates. One technique that can prevent concrete from flaking is to apply a good water sealant to the finished surface to prevent water from entering the concrete. Rust on the rebar takes up more space than the original rebar, resulting in pressure build-up and, consequently, chipping. CPT carries out concrete testing work as well as manufacturing state-of-the-art corrosion control technology.
Splinters can appear because the rebar has been exposed and moisture and water have started to rust the rebar or because the concrete joints were not built properly. The concrete cover is the thickness of the concrete between the outer edge of the concrete member and the steel bar, which covers or protects the steel from exposure to external elements. Concrete is a good bet for durability, and the look of concrete has become increasingly sophisticated and artistic over the years. Splinters can also be avoided if concrete is handled with care and appropriate techniques are used when pouring, such as providing adequate concrete coverage (embedding) of rebar and placing joints in the right places and at the right distances.
Concrete repairs must be carried out in accordance with BS EN 1504, the European and British standard for the repair and protection of reinforced concrete. . .