Bleeding and Preventive Measures
Defination- Bleeding Is a Particular form of segregation in which water comes to top of the concrete.
- The accumulation of water on the outer surface of the concrete is
- Bleeding is good to an extent if it occurs when concrete is Plastic
- While the concrete is still plastic, the accumulated water due to bleeding can be used to mix concrete again and improve workability
- M10 is used for Mass concrete works, dams, etc. M20 is used for R.C.C.
structures. M15 can be used for ground floor construction also
Laitance - Formation of cement paste at surface is called as Laitance
Bleeding can be reduced by-
- Ensuring the correct proportioning of concrete is essential.
- Proper proportioning
- Uniform and complete mixing
- using air-entraining agent
- using cement with low alkali content
- Achieving a thorough and consistent mixing of concrete is crucial.
- Utilising finer cement helps mitigate bleeding issues.
- Controlled vibration is an effective strategy to reduce bleeding, especially when it occurs in fresh and plastic concrete; controlled revibration can counteract the adverse effects of bleeding
Bleeding various causes-
- Excessive water weakens concrete, leading to upward movement of water during settlement.
- Bleeding is more likely to occur in wet concrete mixes.
- Normal bleeding is beneficial for workability if the rate of water evaporation matches the rate of bleeding
