Procedure:
1. This process is equipment oriented. It requires form work in the form of channels, internal vibrators, double beam screed board vibrator for full width, bull float, filter pads, vacuum pump, disc floater and power trowel
2. First concrete with relatively higher water cement ratio to facilitate full compaction with needle vibrator is poured then concrete is further compacted by double beam screed vibrator. This makes the surface smooth
3. Filter map is placed and it is pressed on all the four sides and effectively sealed. Within about 30 minutes, the vacuum pumps are started which sucks the unwanted water
4. Vacuum pump is run for about 20 to 30 minutes depending upon thickness of concrete floor. Vacuum dewatered become stiff and workable. The top surface may undergo a depression of about 3%, with loss of about 20% of original water.
5. Then the concrete is skim floated and further power troweled and finished. Often surface hardeners
are used in conjunction with dewatering process
6. After vacuum dewatering , it gives the ideal condition for application of surface hardeners in power
form
7. The application of disc float and power trowelling may act like reverberation of concrete to eliminate
or segment the continuous capillaries of channels formed in suction of water.
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