MODULE 1
VACCUM DEWATERING OF
CONCRETE FLOOR
• It permits to add as much of water to make concrete
workable and pourable.
• Addition of water reduces the strength of the concrete.
• This system removes excess water and maintain ideal
water/cement ratio.
• This system will maintain all properties of the concrete.
• Vacuum de-watering (VDF) is a process by which excess water
is removed in a controlled fashion by applying vacuum.
• The concrete is then power- toweled to obtain a smooth and
dense concrete.
• This type of flooring achieve strength earlier compared to
conventional method.
• Due to controlled water-removal as well as power-power
trowelling, the surface is quite dense and levelled and hence
is expected to provide a better abrasion resistance than a
non- VDF concrete floor.
INSTRUMENTS USED IN VDF
Vaccum de-watering pump
• Vacuum pump is used to reduce water content in the
concrete by 15-25%.
• It is used to suck all the air bubbles that may have
trapped during the laying of the concrete.
Floater Machine
• Floating and troweling take place right after
dewatering.
• This makes the cement more compact and
enabling to generate a very smooth finish.
Tremix skin
• Suction mat of special grade multilayered
polymer sheets ensure sufficient
cross-sectional area to squeeze out and
remove excess water from the concrete.
Double Beam Screed Vibrator
• Double beam screed vibrator consists of a
beam unit and a vibrator unit.
• Double beam screed vibrator is used to
vibrate the concrete to give a compact and
levelled surface.
Vacuum Dewatering Process
• Preparation of sub base
• Divide floor area into panels
• Preparation of framework using steel
channels.
• Laying down of steel bars of specified size.
• Mix design of concrete
• Placing of concrete and compacting
• The vacuum dewatering process removes
surplus water present in the concrete.
• This is done using vacuum equipment comprising of
suction mat top cover, filter pads and vacuum pump.
• This process starts immediately after surface
vibration.
• Filter pads are placed on the fresh concrete leaving
about 4 inches of fresh concrete exposed on all sides.
• The top cover is then placed on the filter pads and
rolled out till it cover the strips of exposed concrete
on all sides.
• The top cover is then connected to the vacuum
pump through a suction hose and the pump is
started.
• Vacuum is immediately created between the filter
pads and the top cover.
• Atmospheric pressure compresses the concrete and
the surplus water is squeezed out.
• This process lowers the water content in the
concrete by 15-25%.
• The dewatering operation takes approximately 1.5-2
minutes per centimeter thickness of the floor.
• The dewatered concrete is compacted and dried to
such an extent that is possible to walk on it without
leaving any foot prints.
• This is the indication of concrete being properly
dewatered and ready for finishing.
The filter pads are placed so that there will be a
sealing edge around the entire filter pad surface.
Advantages of VDF
• Reduction in W/C ratio leads to early setting and
high strength.
• It removes the excess water of the concrete and an
idea W/C ratio can be achieved.
• Increase in compressive strength of concrete by
40-70%
• The surface hardness of the slab increase by 130%.
• Water absorption is reduced enormously.
• Minimum dusts.
• Level floor, high flatness accuracy.
• Minimized crack formation, shrinkage reduced by
50%.
• Improved wear resistance.
• Elimination or minimization of overtime.
• High and early strength , minimize damage to newly
cast floors.
• Void-free and denser concrete.
Applications of VDF
• Warehouses
• Roads, sports courts
• Cellars, parking areas
• Production areas
• Industrial shop floors
• Base floor for resinous floors-epoxy , PU,Mat,Carpets
and wooden floors.
