Concrete Delamination Causes And Effects
Concrete delamination means the separation of thin layers of concrete from the concrete surface. The stripped concrete surface is susceptible to different types of abraders in the environment and as a result the structures becomes significantly weak. So, before it expands any more, the affected area should be determined and proper corrective measured should be taken. To detect concrete delamination, normally, the concrete surface is struck with a hammer to check whether a drummy sound is produced or not.
What Causes Concrete Delamination
The delamination of the concrete surface mainly occurs for the timing of final trowelling operations. To get rid of this issue, the finishing operations i.e. trowelling should be initiated only after the preliminary setting time of the concrete.
Performing the trowelling operation prior to the initial setting time leads to development of blisters by the bleeding water or air beneath. If the surface is prone to any kind of load action, these blisters would delaminate out.
Starting the finishing processes prior to completion of the bleeding, traps the water or air-voids underneath the finishing layer. Consequently, subsurface voids are produced to make that concrete zone feeble. In due course of time, these subsurface voids are separated with loads.
Delamination also happens for the following reasons :
- The application of a sticky mortar mix with a vast amount of fines.
- Extreme evaporation.
- Fast completion of finishing works.
If the finishing work is accomplished rapidly, the delamination issue is expanded over the whole area. It impacts greater zones of the concrete surface.
This detachment layers remain in 3 to 6mm thick. Delamination is mostly found in concrete slabs.
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Impact of Delamination on Concrete Performance
When the delamination is expanded across the concrete surface, the performance of the concrete surface is reduced significantly. Delamination also leads to disjointing of the flooring material from the top surface of the concrete.
Delamination tears up any top coat on the concrete surface and moisture enters through pathways. Moisture penetration develops cracks and the performance of the structure is impacted.
Remedies for Concrete Delamination
To get rid of delamination, the following points should be taken into consideration :
- The consistency at which the concrete is placed
- The rate of bleeding
- The setting time of the concrete surface
- The rate of surface evaporation
- The method of finishing
It is also required to provide sufficient time for the bleeding water to arise and vaporize before finishing process allows circumventing the issue of delamination. This time refers to the initial setting time of the concrete.
It is also necessary to eliminate the faulty concrete layer at a depth unless robust concrete layer is attained. The unstable concrete is eliminated with the followings :
- Shotblasting
- Hydrodemolition
- Grinding
Once the affected surface is taken out, a new layer is arranged. The entire area can be then ground and flattened to attain a final smooth and sealed finish.
