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Vacuum concrete


      Vacuum concrete :- Vacuum concrete is the type of concrete in which the excess water is removed for improving concrete strength. The water is removed by use of vacuum mats connected to a vacuum pump.
Ø Advantages of Vacuum Concrete :-

Ø  The final strength of concrete is increased by about 25%.
Ø  Sufficient decrease in The permeability of concrete is sufficiently decreased.
Ø  Vacuum concrete stiffens very rapidly so that the form-works can be removed within 30 minutes of casting even on columns of 20 ft. high.
Ø  This is of considerable economic value, particularly in a precast factory as the forms can be reused at frequent intervals.
Ø  The bond strength of vacuum concrete is about 20% higher.
Ø  The density of vacuum concrete is higher.
Ø  The surface of vacuum concrete is entirely free from pitting and the uppermost 1/16 inch is highly resistant to abrasion. These characteristics are of special importance in the construction of concrete structures which are to be in contact with flowing water at a high velocity.
Ø  It bonds well to old concrete and can, therefore, be used for resurfacing road slabs and other repair works.

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