1) High water cement ratio is harm full to overall quantity of concrete. Whereas low water cement ratio does not give enough work-ability of concrete to be compacted hundred percent.

2) Vacuum process help a high workable concrete to high strength.

3) In this process excess water used to higher work-ability. Not required for hydration and harmful in many ways to the hardened concrete is withdrawn by mean of vacuum pump subsequent to placing the concrete.

4) Equipment as shown in fig. Is essential consist of vacuum pump,water separator and filtering mat.

5) The filtering consist of a backing peace with a rubber seal all round the periphery.

6) A sheet of expanded metal and then a sheet of wire gauge also forms part of the filtering mat. The op of suction mat is connected to the vacuum pump.

7) When vacuum pump operated suction is crated within the boundary of suction mat and excess of water suck from the concrete through the fine wire gauge or muslin cloth.

8) At least one phase of the concrete must be open to the atmosphere to create difference of pressure.

9) The contraction of concrete cause by loss of water must be vibrated.

10) Vacuum processing can be carried out either from top surface or from the side surface.