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Dressing up Decrepit Concrete Floors

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Dressing up Decrepit Concrete Floors

by Allan Staines

An old concrete floor that is essentially sound but in shabby condition, can be rejuvenated. Here are a few tips...

Firstly, check for cracking. Large cracks are indicative of serious problems such as ground movement, insufficient reinforcement or damage by heavy trucks or similar. This situation may require serious remedial attention. Hairline cracks are mainly cosmetic - all floors have them.

Hire a water pressure cleaner to give the floor a good scouring. (Be sure to wear protective footwear to prevent injury). Avoid holding the powerful water jet too close. It could strip a trowelled surface in the concrete.

Alternatively, apply liquid chlorine across the surface, wait 20 minutes then scrub off thoroughly with a stiff broom and hose (always read instructions on proper use carefully). If chlorinated runoff flows onto gardens, it will damage your plants, so be careful and if this happens, rinse thoroughly (within your own water restriction guidelines where applicable).

If the floor is indoors, stand protective covers or sheeting around the walls to prevent moisture penetration. If the floor is stained, apply a coat of diluted hydrochloric acid (dilute one part acid to six to ten parts of water in a plastic bucket). Place the acid into the water. Wear protective goggles and clothing, and always read the safety instructions before using any hazardous materials such as acid). After coating, wait until the reaction has ceased then clean off thoroughly with your hose.

Rust stains, with or without cracking often indicates that reinforcing steel placed in the concrete at time of pouring has not been sufficiently embedded and is being affected by the weather. The crack could be increased in width then filled with something like Sikadur-52. Alternatively, if the patch is constantly damp, there could be a water leak under the concrete. This may need to be checked out further.

Oil stains can be a major problem when rejuvenating old concrete floors. For light oil stains, you will find that hydrochloric acid usually solves the problem. Again, use as described above, be very careful and follow all safety instructions before use.For heavy oil and grease patches, use the acid treatment a few times. Old oil stains tend to continue to rise to the surface. As an alternative, you could try steam blasting the stains.

It may be worthwhile scabbling the surface with a kanga hammer and resurfacing the area with a product such as Ardex K15. On outdoor concrete, you could use Ardex K200. Follow the labeled instructions carefully. You will need to acid clean the raw surface first, followed by a prime coat of Ardex 51.

Painting Concrete

Some good preparations are available for painting concrete, and for a great finish you have the choice of gloss or non-slip paints. The non-slip is obviously very practical, whereas gloss is easier to clean, but when wet can be quite slippery. You can always apply a non-slip preparation available from some tile shops.

Before you start, allow the concrete to become bone dry then apply the paint with a long-handled paint roller. Apply two or three coats for a deep lustre.

Paving Concrete

The existing concrete may provide an ideal base to receive pavers. If using on a path or driveway, the overall height above grass or ground level will be increased - bear this in mind before starting. If needed, ramp up the surrounding soil to overcome any problem here.

On driveways, check if the extra height will still allow at least a 15mm step up to the garage floor. This is to keep water out of your garage under normal wet conditions.

Finally: you can Tile it

Patios can gain a new zest when updated with stylish tiles. Be aware that you may have to lay a wall flashing when abutting timber walls to maintain waterproofing. You may also have to adjust clearances on exterior opening-out doors to accommodate the new floor height.

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