Polished Concrete Floors

Introduction
Polished concrete floors provide an affordable alternative to expensive floor treatments, with a wide range of colours and finished that are comparable in terms of appearance, to those of tiles, vinyl and cork. They are energy efficient and offer a low maintenance and dust free floor.

The concept of a polished finish dates back some 20 to 30 years and was originally used to describe the process whereby a typical grey or coloured concrete floor was coated with a wax product and then highly polished. The wax used was generally powdered beeswax. The surface was then polished by rubbing vigorously with a soft cloth, hence the term “polished concrete floors”.

These days while the name remains, the final surface finish can be achieved in a variety of ways. Modern finishes such as liquid polishes, latex coatings, chemical sealers, grinding (to expose the aggregates), using colours and special aggregates to achieve ‘rock or marble’ type finishes are all economical ways of achieving a variety of effects.

Polished concrete finishes have been generally associated with slab-on-ground type construction. However with the variety of economical concrete solutions currently available for suspended slabs, there is no limit to the application of polished concrete floors.

Achieving the Surface Finish
Because of the ‘polished’ look of the surface a good quality steel trowelled finish is usually required to the concrete surface. However some people consider a few trowelling marks create texture and add interest to the finish. Power trowelling by using what is known as a ‘helicopter’ is the easiest way of producing a very flat, even surface. This is best done prior to the walls being built, and necessitates the protection of the slab surface during subsequent construction.

Polished Exposed Aggregate Finish
To achieve this finish the surface of the slab is ground to remove the cement paste, in order to expose the aggregate or stones within the concrete or topping mix. The surface is then polished using progressively finer grinding pads.

Usually because the cost of grinding or polishing is an additional expense, special aggregates are often selected to achieve the best appearance from this type of finish. Aggregate colours, types (round or crushed), sizes, minerals etc can all be selected and blended to achieve the desired effect. Two things need to be remembered: the hard durable aggregates used in decorative concrete mixes will increase the cost of grinding pads as they will wear faster. On the other hand, fewer grades of pads (coarse to fine) are required to produce a polished finish on a concrete slab. Overall, the cost should still be less than that of a tiled finish to the slab, and the possible effects can be stunning. Secondly, it is easier to grind the slab prior to walls being built because there are no edges or corners to worry about. In this case, protection of the surface is required.

Sealing the Surface
The final process involved in a polished floor is the application of a surface sealer. A range of options exist from wax-based products to various other chemical sealers which give a durable, long-wearing protective coating to the surface.

The skid resistance of polished concrete floors also needs to be considered as the sealed surface can become slippery when wet. The use of measures to provide skid resistance therefore overcomes any problem using this finish outdoors.

Maintenance
Polished concrete floors are easy to maintain with only regular cleaning required. The sealer prevents staining and should keep the finish looking good for years.

Conclusion
The current trend towards a low maintenance and dust free (and hence reduced dust mite) environment, produces a healthier living environment generally. Polished concrete floors are an ideal low cost solution, well suited to houses designed using passive solar design techniques. To produce energy efficient housing, more and more people are utilising the inherent benefits of concrete slabs.

As concrete slabs are a lifetime investment, long term durability is also achieved. Whenever the finish starts looking a little dull, recoating can easily restore the floor to its original appearance.

(FROM ‘BRIEFING 05 AUGUST 2001’
THE CEMENT AND CONCRETE ASSOCIATION OF AUSTRALIA)
www.concrete.net.au