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Common Concrete Polishing Mistakes

Author: Angela Joseph
by Angela Joseph
Posted: Jul 16, 2018

Making a polished concrete floor is a specialised operation requiring a good working knowledge of cement and the way a grinding and polishing machines work to avoid mistakes.

First Mistake; is selecting the wrong metal bond diamond tool for the hardness of the concrete you are polishing causing the diamonds to overheat wear out and glaze over the concrete.

The general rule when selecting the right type of diamond cutter is:

Soft Concrete requires Hard Bond Diamonds

Medium Concrete requires Medium Bond Diamonds

Hard Concrete requires Soft Bond Diamonds

Very Hard Concrete requires Extra soft Diamonds

Second Mistake; running the grinding machine too fast

This results in an overheated machine and diamonds glaze and not cutting properly. Most machines run at between 400 to 1200 rpm with the optimum speed of operation about 600rpm or a setting of 4.5 to 5.5. Then the speed is adjusted slightly depending on the concrete and the desired finish required. To give his the best cutting performance and working life from the diamond cutters.

The downward pressure rather than the speed is the greatest determining factor in the speed of the operation and higher production rates.

Third Mistake; is selecting the cheapest priced diamond cutters not the best quality as poor diamonds will wear inconsistently and faster as well as tending to scratch the floor. The better quality diamond cutters are backed by the vendors support and warranties, they also stand behind their products

Fourth Mistake; it is vital to inspect the floor in great detail to ensure that there is nothing raised above the floor surface. Any material above grade (raised above the concrete surface) must be ground off by hand grinder or hammered flat/ Metal bond diamond cutters will polish and grind everything in your floor, including steel, glass, brass and stone as long as it is not proud. If you do encounter proud objects it could damage the diamond cutter and your machine.

Fifth Mistake; is when the operator does not really understand the process necessary to achieve the desired outcome. When you want a "Cream Polish" then you never start with a heavy diamond cutter as this will remove the top layer and expose the aggregate below.

Determine what you have to remove before you start and what the finish you want.

Remove all the nonconcrete materials, such things as epoxy coatings, ceramic tiles and VCT flooring residues before polishing.

Do not use a heavy diamond cutter on these as it can result in deep scratches that are very difficult or cannot be removed. Start with a light or less aggressive cutter and if necessary more to a move aggressive one.

Most concrete polishing jobs start with a 40g bond Diamond cutter to expose the salt and pepper layer (aggregate)

Sixth Mistake; is not rectifying problems as they occur You must take careful note of the work in progress to ensure that the job is progressing properly. If you see scratches appearing on the polished floor, they must be removed straight away. They cannot be removed later with the next polishing, they will only get worse and spoil the job.

Seventh Mistake; it is important to make sure that you understand that an old concrete floor is not perfect and you will always get what is called a character, polished floor unless the floor is overlaid with a special concrete coating to get a specific effect. All concrete floors were never meant to be polished and although you can get a very attractive finish it will always include some imperfections.

About the Author

Hardcore Concrete is a Concrete Polishing Gold Coast based company servicing a wide variety of customers including Architects, Interior designers.

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Author: Angela Joseph

Angela Joseph

Member since: Jun 03, 2018
Published articles: 14

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