Can badly poured concrete be polished?

Polished concrete floors by PMAC with a Silver finish in large Office Dublin

It is hardly surprising that Polished concrete floors are becoming the most sought after flooring solution for both commercial and residential use. Polished concrete floors are beautiful, durable and also tick all the boxes when it comes to sustainability. A concrete slab is an essential requirement for any new build, by polishing your concrete you are making use of materials already in the building. It is crucial however to ensure your concrete slab is poured with the intention of polishing, after all this is your finished floor

An eco friendly sustainable flooring solution:

Concrete is sourced locally from local quarries so comes with a low carbon footprint.

A polished concrete floor is achieved by grinding and polishing your concrete slab until you reach the desired finish. No need to add glues, epoxies, tiles, carpets, lino, waxes etc. Your concrete slab is your finished floor.

Your polished concrete floor will last a lifetime. No need to replace when it gets worn or dirty. No need for cyclical waxing. A concrete floor will get dull and stained over time, your maintenance regime will determine how quickly this will happen. However, a polished concrete floor can always be stripped and re-polished every few years and brought back to new every time.

A Polished concrete floor is extremely durable and resistant and won’t chip or scratch.

Your concrete pour is the most important element to get right:

The most important factor to consider when installing a polished concrete floor is to understand your concrete slab is your finished floor. Therefore the most crucial element to get right.

At PMAC we don’t pour concrete, this is not our area of expertise. Your builder or concrete supplier will carry out this task for you. There are some very important principles to follow to ensure your polished concrete floor is laid and left in perfect condition for polishing.

Here are our top tips on specifying the supply and pour of concrete suitable for polishing:

Specifying concrete for a polished concrete floor

Ensure your concrete supplier is aware the concrete is intended for a polished concrete finish.

Ensure they use polypropylene fibres in the mix

There should be no fewer than 3 aggregate sizes in the mix, ranging from 5mm to 20mm. Fine, intermediate, and large aggregate will yield the best visual quality.

Pouring the concrete:

Ensure all rooms are poured on the same day.

Do not add water to the mix to ease the spread of the concrete. It must have a slump value of between 100 and 150.

Make sure the concrete is spread evenly andfitted right up to the edges.

Never tamp the concrete into place or run a poker through it.

Concrete must be power floated and left with an SR1 level finish. This means perfectly level with no dips or bumps.

Ensure no one walks on the concrete during the drying process; this will leave footprints in the concrete that can’t be polished out.

When your concrete is poured:

Your concrete needs to cure for a minimum of 28 days before it can be polished.

Remember this is your finished floor so ensure all heavy work is completed before you install your concrete.

Insert expansion joints at least every 36 m2.

Will my polished concrete floor crack?

Unfortunately nothing can guarantee a concrete floor won’t crack. Concrete is a natural product and highly susceptible to what’s happening underneath. Movement in the foundations or the sub floor will cause cracks. However, the chances of cracks occurring in your polished concrete floor due to the quality of the concrete and the pour are greatly reduced if you adhere to our guidelines.

Can a badly poured concrete floor be polished?

 

Yes, it is possible to carry out remedial works to badly poured concrete. Repairs can be carried out before we start grinding. This of course will incur additional costs.

We visit site 2 -3 weeks after the concrete is poured to inspect the concrete.

A common problem we come cross is uneven levels where dips and bumps are present; remember that SR1 level we specified? Uneven concrete can be ground down but this adds to labour costs. It is also important to remember, grinding exposes the aggregate, the more you grind the bigger the aggregate or size of stones are exposed. This means your only option for your polished concrete finish is a platinum or silver polished concrete floor. A platinum finish is where lots of aggregate are exposed and the concrete is polished up to a high shine. A Silver finish is similar but is left with a matt finish.

Edges that are left higher than the rest of the floor.

These need to be ground down, by hand, to make flush with the rest of the floor. This is slow, labour intensive and costly.

Sometimes problems with the concrete don’t become apparent until we start grinding.

If water was added to the mix during the pour this can leave patchy marks in the concrete or cause the aggregate to sink.

We will always grind a few sample patches across different areas of the floor on day 1. This ensures the client is happy with the finish and dispersion of aggregate.

What can I do if my concrete is not suitable for polishing?

It is very unfortunate if this happens. This is why we always carry out various samples on day 1 to ensure the client is satisfied with the finish before spending money on a floor that doesn’t meet their expectations.

 

Rapid TRU PC floors by PMAC

Rapid TRU Polished concrete overlay floor installed by PMAC

 

All is not lost however if your concrete is not suitable for polishing. You can still achieve a fabulous polished concrete floor. Rather than trying to rectify bad workmanship we recommend pouring a Rapid Tru self-levelling polished concrete overlay on your floor. Read more

 

Rapid Tru delivers a really beautiful concrete floor with all the qualities of a polished concrete floor –  with added benefits! You can choose the exact colour of concrete you want. We take care of the pour and it is ready to polish after only 24 hours. So no more delays on site and a fabulous floor at the end of the day.

In conclusion, our advice is to ensure you engage with a reputable contractor to pour your concrete floor. We will give all the advice they need to avoid pitfalls.

If is does go horribly wrong, don’t waste your money trying to make it right. You would be better off pouring a concrete overlay where you will be guaranteed a high quality, beautiful polished concrete floor.

For more information on any of our services please get in touch at 01 473 3666 or email us at info@pmac.ie