Why cover concrete, when you can polish it?

by Rob

If you are laying a new concrete floor or have an existing concrete subfloor, do you need to cover it? Grinding and then polishing it presents a good sustainable design flooring option because it makes use of the materials already present. Most modern buildings are built on a concrete slab; polishing the exposed concrete eliminates the energy and material consumed by applying a floor covering. It is something to consider when building or modernizing towards a more “green” solution.

Concrete doesn’t have to be dull. Polishing the laitance (sometimes termed ‘fat’) that sits on top of the concrete or exposing its aggregate is extremely popular for Industrial, Commercial and Residential projects.

A laitance polish is where only the very thin top layer is polished to a finish. It is carried out with resin diamonds or a very fine and gentle pass with metal diamonds first, so as to not expose any aggregate. The importance of a good initial concrete install is critical, as this method is only polishing the top layer and will not level out a badly laid, uneven surface. A minimal amount of material is removed which gives a deep cloudy look with plenty of character. An exposed aggregate polish is produced by removing the top surface laitance and grinding down to the centre of the first layer of aggregate, then polishing to a terrazzo type finish to the degree of shine required. Its composition will naturally dictate the finished result.

A variable speed multi-head grinder such as a Terrco® Grinding & Polishing machine, where the configuration of the heads provides a more efficient operation, gives greater surface coverage for high production rates with minimal effort. For small projects, inaccessible areas or edges, an STG machine fitted with diamond accessories can be more suitable. These machines can be used for wet or dry grinding and polishing. Wet grinding extends the life of the diamond, but creates slurry that must be collected and disposed of carefully by using an industrial vacuum with wet/dry capability such as an M450. Dry grinding is a cleaner process, with the machine connected to an Industrial Vacuum or Filtration Unit.

When new concrete is laid, colouring agents and coloured aggregate can be incorporated into the mix to produce a decorative effect. It is important that the concrete is laid in a uniform manner to produce a consistent finish.

When the concrete floor is old, uneven or covered, it isn’t ready to simply start the polishing process, another preparation method may be needed first. It is important to note that, again, grinding will not level out a badly laid uneven surface and will skip over any low spots. Before considering concrete polishing, it needs to be established if the surface is cracked or has evident defects and what type of aggregate it is; its size, colour mix and percentage.

After completing the grinding process and in the early resin stage of the polishing, a chemical hardener or densifier can be applied. The timing of this depends on the composition of the concrete. The densifier bonds the surface, provides extra protection from contaminant penetration and produces a better polish. It reacts with the calcium hydroxide in the concrete to form a hard, crystalline structure. It is essential that the last grind prior to applying the densifier is scratch free, as the resulting hardened surface makes removing scratches much more time consuming.

When the polishing process is complete and to uphold the floor’s sustainability credentials, the only maintenance required is cleaning using a diamond infused pad and water such as Storm Diamond Pads, suitable for an STG450, Burnishers and Rotary Scrubber Dryers.

For project and equipment advice call 01522 561460, or email hello@ppcgroup.co.uk.


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