Acid Cleaning of Pavers Instructions from Austral Bricks

The appearance of a paved area can be spoilt by bad cleaning techniques or by the use of the wrong cleaning agent.

For this reason, it is important to ensure that the correct cleaning methods are utilised for the best results and to help reduce any associated problems with cleaning.

Figure 1. Burnt vanadium stains. This Riviera paver was subjected to poor cleaning practice

Acid Cleaning

Acid cleaning using hydrochloric acid (HCl) should normally only be used to remove mortar stains. Therefore, only pavers that have been wet-bedded may require acid cleaning. Generally, hydrochloric acid should not be used to treat any other stains or at any other time during the life of your clay product. If used incorrectly, it can cause unsightly staining that is more difficult to remove.

Cleaning Mortar Residue

The practice of cleaning mortar residue 'as you go' during laying should normally eliminate the need for acid cleaning. Wet-bedded Riviera pavers from Austral Bricks should normally be cleaned using this technique. If acid cleaning is used, particular care should be taken to follow the correct cleaning procedure.

Vanadium Stains

Any vanadium stains should be treated prior to acid cleaning. Vanadium stains are a yellow-green harmless discolouration on the face of a clay product, which can occur especially in light coloured clay products. Acid cleaning prior to treating vanadium stains can result in the stain becoming more unsightly and more difficult to remove.

Acid Burn

'Acid burn' is caused by the use of an incorrect acid cleaning procedure. The acid reacts with iron oxides naturally present in pavers or mortar to cause the stains.

Cleaning Tips

Helpful acid cleaning tips:

• Always use adequate safety precautions!
• Reduce the need for acid cleaning by cleaning 'as you go' during laying.
• Ensure sufficient pre-wetting of the pavers prior to applying hydrochloric acid.
• Apply an acid solution of the correct strength. Acid solutions that are too strong are a problem.
• Ensure that the pavers are sufficiently rinsed after cleaning. Light coloured pavers should be rinsed with a neutralising solution.

Source: Austral Bricks
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