National Masonry Cleaning Recommendations
Below is a general guide to Cleaning & Maintenance for Concrete Pavers, Concrete Blocks and Retaining Walls.
Cleaning Concrete Pavers
A carefully planned Cleaning & Maintenance program is the best method to keep pavers looking good for years to come.
Simple steps should include:
- Regular sweeping to keep the pavers free from debris;
- During construction, cover the paved areas to protect against damage;
- Protecting against possible staining from mortar, oxides, cement and rust;
- Do not stack pavers in a ‘criss-cross’ pattern as permanent hydration stains may result on corners;
- Do not use a high pressure cleaning apparatus.
- Prior to removing stains, we suggest that the type of stain be carefully assessed before action proceeds. Incorrect assessment can lead to the stain being more difficult to remove. If the stain
- cannot be accurately assessed, then we would recommend that a trial process on a small portion of the stained area be undertaken to determine the most appropriate action.
A guide to Concrete Paver common stains
This is a salty deposit on the surface of pavers which appears as anything from strong, powdery, white blotches through to a fine white haze that can make pavers or blocks look “faded” and is generally the result of a chemical reaction that takes place as concrete cures. Efflorescence may also soak into pavers or blocks from salt deposits in adjacent materials such as bedding sand, joint sand or soil.
Rain will generally dissolve efflorescence and gradually wash it out of the paver or block over time. Stubborn patches may require cleaning with a stiff bristled nylon brush or colourless plastic scouring pad (do not use deeply coloured or metallic brushes or scourers as they will leave marks). It is important to brush away powder residue and then rinse and brush the area thoroughly with clean water after breaking up the efflorescence otherwise it may simply soak back in and re-stain the area again. If stronger methods are required, reputable sealers from manufacturers such as ENVIRONEX and Drytreat and other efflorescence cleaners are available through good Landscape Supply stores.
Cleaning & Maintenance – Moss, Mould and Leaf Stains
Soak the area with a domestic bleach or a solution of five parts water with one part pool chlorine. Leave for ten minutes then gently hose down before the solution dries.
Cleaning & Maintenance – Sealing of Concrete Pavers
For maximum protection, National Masonry™ recommends that all pavers should be sealed with a quality penetrating sealer following installation. Please check with a qualified tradesperson for advice on this process. National Masonry™ does not accept liability for stained or damaged pavers once laid.
WARNING: Hydrochloric acid is NOT recommended for use with concrete pavers as irreparable surface damage may occur.
Efflorescence can occur on masonry construction, when water moving through a wall or other structure, or water being driven out as a result of the heat of hydration as cement stone is being formed, brings salts to the surface that are not commonly bound as part of the cement stone. As the water evaporates, it leaves the salt behind, which forms a white, fluffy deposit, that can normally be brushed off. The resulting white deposits are referred to as “efflorescence” in this instance. In this context efflorescence is sometimes referred to as “saltpetering.” Since primary efflorescence brings out salts that are not ordinarily part of the cement stone, it is not a structural, but, rather, an aesthetic concern.
Cleaning & Maintenance of Retaining Walls, Concrete Bricks and Grey Concrete Blocks
- Block layers must exercise extra care when laying and tooling.
- Keep unused pallets of blocks and tops of unfinished wall covered during rain to prevent water penetration and the resulting excessive efflorescence.
- Clean any dags and mortar smears before they set hard.
- There are various methods of general cleaning from dry brushing to pressure water washing and depending on the extent of cleaning required may involve the use of chemicals.
- If the treatment necessitates the use of chemicals such as Hydrochloric acids all care must be taken. Acids such as Hydrochloric react with and dissolve cement, lime and oxide colours in
- concrete blocks and mortar joints and are thus capable of etching ,fading and streaking the masonry finish. This in most cases cannot be reversed.
- For a fully detailed guide on masonry cleaning please refer to the following concrete masonry association website under technical information, cleaning of masonry. www.cmaa.com.au
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