Polished concrete is mechanised process using heavy-duty polishing machines equipped with progressively finer grits of diamond-impregnated segments or disks to gradually hone down surfaces to the desired degree of shine and smoothness. Instead of applying a weaker and insignificant product to the concrete, this process refines and enhance the qualities that is naturally inherent within the concrete.
The process begins with the use of coarse diamond segments bonded in a metallic matrix. These segments are coarse enough to remove minor pits, blemishes, stains, or light coatings from the floor in preparation for final smoothing. Depending on the condition of the concrete, this initial rough grinding is generally a three to four step process.
The next steps involve fine grinding of the concrete surface using diamond abrasives embedded in a plastic or resin matrix. Ever-finer grits of polishing disks are used until the floor has the desired sheen. For an extremely high-gloss finish, a final grit of may be used. Experienced polishing crews know when to switch to the next-finer grit by observing the floor surface and the amount of material being removed.
Polished concrete flooring is cost effective as it saves businesses time and money on monthly waxing and polishing. These shiny floors are permanently polished, easy to maintain, and are not slippery. Slip-resistance meets ADA and OSHA standards. For maintenance, simply use a mop or gentle machine scrub to clean the floor.
Concrete polishing is a 7-stage process of which the first four stages is known as concrete grinding. During the grinding stages, approximately 4mm floor thickness is reduced, dependent on the initial concrete quality and condition. During the remaining 3 stages of polishing, approximately 1mm of floor thickness is reduced. The grinding stages determine the exposure level of the floor albeit no or limited exposure, salt and pepper exposure or full aggregate exposure.
The concrete floor to be polished must be at least 25MPa and placed by an expert concrete placing contractor. A limited percentage of the final floor outcome is determined by the grinding and polishing stages. The majority of the final product is determined by the concrete or flooring substrate that is placed and the preparation that follows, prior to grinding and polishing. If a decision is made to polish concrete in advance of concrete being poured, the array of available options becomes almost unlimited.
CAN ALL CONCRETE BE POLISHED?
Almost any structurally sound concrete floor, whether new or old, can be polished, with some exceptions.
For new floors, no special mix design is required to achieve good results. The floor should be placed at least 7 days prior the main grind and 28 days before high polishing begins to ensure adequate curing. Some retail and warehouse facilities that plan to polish their floors after placement may specify the installation of as smooth a floor as possible to minimize the polishing steps required.
Existing floors typically require some surface preparation prior to polishing to remove dirt, grease, coatings, or blemishes. Uneven floor may need extensive patching, sealing or rework and some extremely porous floors may not be good candidates for polishing. Floor suitability should be determined by the contractor.
According to the ADA, OSHA and ASTM guidelines, ground and floor surfaces shall be considered slip resistant if the measured static coefficient of friction is a minimum 0.5 when tested in accordance with either ASTM C-1028 (field or laboratory test) or ASTM D-2047 (laboratory test) methods.
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