Spalling of concrete is defined as the breaking off of pieces or layers of concrete from the surface of a structural element when the concrete is exposed to high temperature as experienced in case of fire.
The corrosion of steel or other metals can also lead to spalling. Because when steel corrodes, the resulting rust occupies a greater volume than the steel.
Spalling ranges from insignificant aggregate spalling (which causes surface pitting) to, in extreme cases, large parts of walls and floors being blown off with explosive force:
It is the surface failure that occurs when a material such as concrete, bricks or the limestones are subjected to excess moisture, corrosion, weathering etc.
Concrete spalling is commonly known as the Concrete Cancer which is an eye-sore and having the potential to be an extreme hazard. It can cause structural damage to the structures.
Causes of the Spalling of Concrete
- The corrosion of steel and other embedded materials which causes the deterioration of concrete.
- High and rapidly rising temperature
- Exposure of the reinforced concrete to chloride ions is another primary reason for the spalling which causes the deterioration of concrete.
- It can be caused due to the natural deterioration and carbonation process is responsible for it. So, the spalling after a period of fifty or more than fifty years is due to the carbonation process.
- Freezing and thawing action is responsible for the spalling of concrete as water is one of the important constituent of the concrete plays a very curious role and if it freezes it can expand by about 9%.
- Expansion of the aggregates is also responsible for the spalling of concrete.
- Chemical attacks and the exposures of concrete to different environmental conditions like acid rain having a serious effect on the concrete and which leads to the deterioration of concrete.
How to prevent the spalling of Concrete?
- We should mix the ingredients properly to prevent the deterioration of concrete
- We should provide distinct care to the ends and corners of the bare concrete.
- Corrosion of the metals which are fixed in the concrete can be minimized by placing crack-free concrete with low absorptive index and adequate concrete cove.
- For tackling the spalling of concrete the judgement should be made in time.
- For preventing the moisture one should use a Concrete Treat as a sealer on outdoor and indoor concrete.
- We should also apply water-repellent sealer after the slab is cured.
How to repair Spalling of Concrete?
- Remove the concrete at the spalled areas for exposing the corroded steel bars.
- Scrap and clean the exposed steel bars and uses a wire brush for removing the rust.
- We should also apply two coats of anti-rusting paint to the steel bars.
- Before patching the area we should apply a bonding agent to the affected surface for ensuring proper adhesion.
- We should patch up the hacked area by making use of polymer modified cement mortar.
As we all know that Spalling of Concrete is causing structural damages in various aspects. It can be a serious headache for the owner of the house. It can reduce the average life of the concrete. So, the spalling concrete can decrease the half-life of the structure. We should take proper steps for preventing and repairing it in time.
Also Read: Structural Audit