What Causes Concrete Spalling?
Spalling Of Concrete (also known as Concrete Cancer or Concrete Spalling) is aggressive rusting of steel reinforcement beams in the concrete slab
which can be incredibly dangerous to the strength of the structure and flooring.
Spalling Of Concrete will start to damage the concrete and steel reinforcing beams in the concrete slab.
Concrete Spalling Sydney offers a free inspection of the concrete slab to inspect for any Spalling Of Concrete. Which should always be done before installing a new floor topping, especially if you have recently removed a Magnesite Flooring.
Firstly, Spalling Of Concrete is not attractive and makes a structure look uncared for. More seriously, if the structure is in an area accessed by the public, or by workers, then Spalling Of Concrete can be hazardous in terms of falling debris or trip hazards.
If left unchecked then Spalling Of Concrete will tend to accelerate and spread so that, eventually, the structure could become unstable. Diligent maintenance is therefore of great importance and legislation places a duty of care on owners to ensure that structures are not hazardous to users.
There are also serious commercial considerations. If a structure is left to deteriorate then the value of the asset will diminish and, furthermore, maintenance costs will tend to increase as corrosion and Spalling Of Concrete becomes more widespread. For some structures, such as car parks, customers will stay away if the environment is unattractive and potentially hazardous.
Spalling Of Concrete – especially on the outside of a building – not only looks terrible, but it is potentially dangerous too. Over time, and with increased exposure to the elements, untreated pieces of concrete may fall from your structure. The risk is it falling and damaging property, or even worse, hitting a person walking below.
There are a number of reasons your building may have Spalling Of Concrete.
Spalling Of Concrete usually occurs for one of three reasons, or sometimes a combination of these reasons. Salt, particularly the sodium chloride that’s used on frozen roads in many northern states, can result in oxidation or rusting of reinforcing steel when it’s repeatedly introduced to a surface or building.
But Spalling Of Concrete is more likely to occur due to the curing process or the way the concrete hardened. Carbon dioxide in the air and alkalis in the concrete mix can also interact and force cracking that admits water.
Common reasons that your building may have Spalling Of Concrete include:
- A poorly poured substrate which has allowed moisture to seep into it through cracks and voids
- Inadequate preparation of the reinforcing steel when the original concrete was poured
- The ends of the reinforcing beams are too close to the surface. In heavy rains, water may seep through causing lime and other chemicals in the steel to oxidise
- Incompatible metals being used in close proximity to each other, thus causing a reaction which allows water into the slab
- Stress fractures from bearing weight or general wear-and-tear allow water to penetrate the concrete and react with the steel
- Corrosion of embedded reinforcing steel, because the corrosion products (rust) occupy more volume than the original steel, and the resultant pressure spalls the concrete.
- Fire exposure due to which free water in the concrete changes to stem and create internal expansive pressure in concrete, consequently spall off the concrete.
- Freeze and thaw cycling
- Expansive effects of Alkali-Silica Reaction
- Inadequate depth of cover over reinforcement
- Low quality concrete cover over reinforcing steel
- Joint spalls are often caused by improperly constructed joints lead to joint spalling
- Bond failure in two-course construction due to Differences in shrinkage between topping and base courses, drying of the bonding grout before the topping concrete is placed, etc
Spalling Of Concrete breaks away pieces of the concrete surface which often extends to the top layers of reinforcing steel. Spalls may be 150 mm or more in diameter and 25mm or more in-depth, and the occurrence of smaller spalls also possible.
Spalling Of Concrete affects a broad variety of structures including framed buildings, multi-story car parks, bridges, jetties, unit blocks, etc.
Spalling Of Concrete leaves the concrete surface patchy and pitted while exposing aggregate underneath. As soon as Spalling Of Concrete is spotted, it should be properly repaired otherwise it compromises concrete surface integrity and jeopardizes the ultimate capacity of the member. Added to that, Spalling Of Concrete could distort the aesthetic appearance of the structure.
Spalling Of Concrete that occurs in a concrete driveway or sidewalk typically happens because the weather changed during the hardening process or something else occurred to prevent the concrete from finishing its curing. Contractors might make the mistake of adding too much water, but frankly, most don’t make mixing errors. Tearing out the driveway isn’t always necessary to fix Spalling Of Concrete. Sometimes the top layer can be removed and a new layer poured in its place.