WHAT IS VACUUM DEWATERING FLOORING
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.
Vacuum dewatered concrete, popularly know tremix in India, is developed by Tremix, Sweden. It is a system for laying high quality concrete floors with superior cost-effectiveness. The key to the use of this method is the dewatering of concrete by vacuum process. Immediately after placing and compaction, excess water is removed by vacuum dewatering process. Thus reducing water content, optimum water to cement ratio can be achieved. A lowered water : cement ratio automatically leads to a noticeable improvement in almost each of the concrete properties.
THE PROCESS OF VACUUM DEWATERING CONCRETE :
It is a vital part to execute all activities in right sequence to obtain good quality of concrete pavement.Initially, poker vibration is essential, especially at the panel edges. Use of needle vibrator ensures elimination of entrapped air and voids. One can not achieve levelled surface while doing compaction with needle vibrator.It is therefore essential to combine this vibration with surface vibration (screeding), in order to obtain a vibrated concrete with levelled 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 is achieved by filter pad, suction mat and pump.. The process starts immediately after surface vibration.
After compaction by surface vibrator, filter pad are placed leaving all sides exposed about 4 “. 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.Water content in the concrete is reduced by 15-20% during vacuum dewatering process.Usually it takes about 1.5 – 2 mins for de watering process for one centimetre thickness of slab.. This is the indication of concrete being properly de watered and ready for finishing.
The finishing operations –
Floating & Trowelling take place right after de watering. 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.