BLEEDING OF CONCRETE

BLEEDING OF CONCRETE AND ITS EFFECT TO CONCRETE

BLEEDING OF CONCRETE

Bleeding is one form of segregation, where water comes out to the surface of the concrete,Bleeding can be easily identified in the field by the appearance of a thin layer of water in the top surface of freshly mixed concrete.

BLEEDING OF CONCRETE


EFFECTS OF BLEEDING OF CONCRETE


  • Due to bleeding concrete loses its homogeneity (the strength will not same at all the point)
  • Bleeding is responsible for causing permeability in concrete.
In the process of bleeding water comes upwards or it will flow from centering boxes,This accumulation of water creates  voids and reduces bond between the reinforcement and concrete.
bleeding can effect workability of concrete.

In pavement construction bleeding water delays surface finishing and application of curing compound.

Bleeding in fresh concrete refers to the process where free water in the mix is pushed upward to the surface due to the settlement of heavier solid particles such  as cement and water. Some bleeding is normal but excessive bleeding can be problematic.

The biggest factor in bleed water rates is the water to cement ratio.A higher ratio can lead to excessive bleeding. The fewer fines you have in your mix, the more bleeding will occur. Factors also include concrete height and pressure. 

TYPES OF BLEEDING 


  • Normal bleeding refers to a uniform seepage of water over the entire surface of the structure.

  • Channel bleeding refers to water rising through particular paths.

Not all bleed water will reach the surface of the concrete. Some bleed water may rise and remain trapped under aggregates and reinforcing.This results in the weakening of the bond between the paste.

HOW TO MINIMIZE BLEEDING 


The use of supplementary cementitious materials can decrease bleeding rates,especially when using finer blends. Fly ash can be effective in reducing bleed rates. 

Silica fume has the largest effect on reducing bleeding.

HOW TO REDUCE BLEEDING IN CONCRETE

BLEEDING OF CONCRETE

  • Reduce water content.Use lower slump mix
  • Use finer cements
  • Increase amount of fines in the sand
If you have any question regarding this please comment or contact us
  

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