Contents:
Methods of Finishing Hardened Concrete Surface
1. Dry Grinding Finishing Method
- Dry grinding is performed on dry concrete surfaces.
- It is used to eliminate fins and marks caused by forms.
- Abrasive discs are used for grinding and its outcome is excellent.
- The abrasive disc constitutes of multiple layer of abrasive-impregnated cotton fiber material bonded together under heat and pressure with strong resin bond.
- Thickness of abrasive is around 6.35mm and its diameter ranges from 17.78cm to 22.86cm.
- Abrasive discs can be used to the work at an angle of 30 to 40 degrees using the weight of the tool for pressure.
- They can be attached to any type of portable tool and should be operated at from 3,000 to 4,000 rpm.
Fig. 1: Finishing hardened concrete (dry grinding method)
Fig. 2: Finishing concrete surface using stand-up edger; drying grinding
2. Wet Rubbing Finishing Method
- It is executed on green concrete.
- The procedure used for finishing hardened concrete using wet rubbing includes apply paints on a coating of cement with hand brush. Then, the wet cement is rubbed in; at this step, use water where necessary.
- Finishing process is conducted by slow speed grinding disc (wheel), at the same time applying water. So, the operator can apply water and grind concrete Simultaneously.
- The water and the rubbing action, brings up a cement paste which makes concrete very smooth, plaster-like surface.
- The grinding disc is utilized with a right-angle head, to which a water hose is attached to, run water through the center of the grinding wheel onto the concrete.
- The wet angle head has various gear reductions to decline the grinding speed to 300 to 500 rpm.
- Pressure tank could be employed for water supply.
Fig. 3: Finishing hardened concrete (wet rubbing method)
Fig. 4: Conventional rotary trowel with brick grinding replaces blades