Vacuum Dewatering Flooring 1. What is VDF Flooring? VDF Flooring also known as Vacuum Dewatered Flooring is a special type of Flooring Technique to achieve High Strength, Longer Life, Better Finish and Faster Work. This type of floor is suitable for high abrasion & heavy traffic movement. The Vacuum Dewatered Flooring or VDF Flooring is a system for laying high quality concrete floors where the key is Dewatering of Concrete by Vacuum Process wherein surplus water from the concrete is removed immediately after placing and and vibration, vibration, thereby thereby reducing the water: water: cement ratio to the optimum level. Concrete Vacuum Dewatering System is a high quality concrete floor or pavement requires not only to be level but it should also have high wear resistance, high compressive strength, reduced shrinkage and minimum water permeability. This method is the dewatering of concrete by vacuum process. Surplus water from the concrete is removed immediately after placing and vibration, reducing the water : cement ratio to an optimum level. Therefore, adopting this method facilitates use of concrete with better workability than what is normally possible. A lowered water : cement ratio automatically leads to a noticeable improvement in almost each of the concrete properties.
2. How to do the VDF Flooring? Procedure: In this system of VDF Flooring or Vacuum Dewatered Flooring, concrete is poured in place & vibrated with a nozzel vibrator especially to the sides of the panel for floor thickness more than 100mm. Then surface vibration is done using double beam screed vibrator running over the surface, supported on channel shuttering spaced 4.0 meters apart. The screed vibrator is run twice to achieve optimum compaction & leveling. The vibrated surface is then leveled using a straight edge.
After this a system of lower mats & top mat is laid on the green concrete & this is attached to a vacuum pump. This draws out surplus water if any. The concrete is left to stiffen. When the base concrete has stiffened to the point when light foot traffic leaves an imprint of about 3-6 mm, Floor Hardener is applied at an even application rate of between 3-5 Kg/Sqmt. Any bleed water should now have evaporated, but the concrete should have a wet sheen. The concrete is then further compacted and leveled using Power Floater followed by finishing as per the requirement using Power Trowel.
Power Floater
Power Trowler
3. What are the Benefits of VDF Flooring?
Increased Compressive Strength Increased Tensile Strength Increased Abrasion Resistance Minimum Shrinkage & Floor Wraps Decreased Cement Consumption
4. What are the Typical Application Areas of VDF Flooring? 1. 2. 3. 4. 5. 6.
Warehouses, Go-downs Roads, Sports Courts Cellars, Parking Areas Production Areas, Pharmaceutical Companies As the base floor for Epoxy & PU Floorings
5. VDF Procedure
In order to obtain a high quality concrete floor using this method, it is essential to follow the various operations in the correct sequence. Initially, nozzle vibration is essential, especially at the panel edges. This results in proper compaction of the concrete and hence elimination of voids and entrapped air. Nozzle vibration never really gives a leveled surface. It is therefore essential to combine this vibration with surface vibration (screeding), in order to obtain a vibrated concrete with a leveled surface. Two passes with surface vibrator are normally recommended. The Surface Vibrator is guided by two men, standing on either side of the panel. Vacuum dewatering process removes surplus water always present in the concrete. This is done using the Vacuum Equipment comprising of Suction Mat Top Cover, Filter pads and Vacuum Pump. The 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 covers 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 approx. 1.5 - 2 minutes per centimeter thickness of the floor. The dewatered concrete is compacted and dried to such an extent that it 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 finishing operations - Floating & Trowelling take place right after dewatering. Floating operation is done with Floating disc. This ensures after mixing of sand & cement particles, further compaction and closing the pores on the surface. Floating operation generates skid-free finish. Trowelling is done with Trowelling blades in order to further improve the wear resistance, minimize dusting and obtain smoother finish. Repeated passes with disc and blades improve the wear resistance substantially.
6. Vacuum Dewatering System Consist Of:1. 2. 3. 4. 5.
Surface Vibrator. 1No. Vacuum Pump. 1 No. Suction Mat Top Cover. 1No. Filter pads. 6Nos. Skim Floater. 2 Nos.
Surface Vibrator Vacuum Pump
Suction Mat Top Cover
Filter Pads
Skim Floater
7. Technical Theory Behind VDF:-
Suction Mat of special grade multilayered polymer sheets along with reinforced distance cushions on the Filter Pads ensure sufficient cross-sectional area to squeeze out and remove excess water from the concrete. This design is a prerequisite for effective dewatering.
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