Part of the
If neglected, even the best, perfectly installed driveway will eventually deteriorate in appearance and performance. Keeping paving in optimum condition requires only a little effort and relatively simple techniques whether it is keeping new paving looking good or giving old neglected paving a new lease of life.
For further information please take a look at our Literature section for our Cleaning and Maintenance Block Paving Factsheet.
All concrete blocks and pavers contain natural substances containing an amount of soluble salts to a lesser or greater degree, depending on the block type and the origin of the raw materials used in their manufacture. This varies from plant to plant due to sourcing local supplies.
Moisture from the manufacturing process or from rain will interact with these soluble salts and will migrate to the surface due to the fact that all concrete products, even our strong and dense pavers are porous to some extent. The Carbon Dioxide in the atmosphere will react with these soluble salts (e.g. Calcium Hydroxide will turn into the insoluble Calcium Carbonate) and as the moisture evaporates the characteristic white, crystalline efflorescence will be left behind.
The mechanism for efflorescence begins as soon as the blocks are manufactured and will continue to the point that the soluble salts are used up within the block and the efflorescence will gradually fade. As the insoluble Carbonate salts are exposed to further Carbon Dioxide in the atmosphere, they will slowly convert into soluble Hydrogen Carbonate substances and will wash away and dissipate naturally.
Efflorescence can come and go over a period of a few weeks but can take many months in some cases. Local conditions and climate play a part; damp shaded areas tend to be more prone to efflorescence than drier sunnier areas and efflorescence can be more pronounced during springtime following a wet winter.
No matter how well constructed a driveway is if it is neglected then detritus will build up and weeds, moss, algae and lichen is likely to establish itself. Therefore, routine cleaning on a seasonal basis is recommended as follows:
On dry paving use a stiff bristled brush to remove any dirt or build up from the surface.
Acid-based chemical cleaners: these products can etch the paving surfaces and affect the pigmentation of the blocks permanently ruining the paving. We recommend that these cleaning products are avoided wherever possible and only used if absolutely necessary!
Any block paving can suffer from weeds if it is neglected and not routinely cleaned. Paving claiming to be “weed-free” is misleading as weeds do not grow through paving blocks themselves or through the sub-bases with the exception of extreme species such as Japanese Knotweed.
Weeds usually establish themselves in the joints and regular cleaning and care as detailed above will keep them at bay. Replace any jointing sand which may have been pulled out with the weed roots. Weed-killers: Regular brushing will tend to keep weeds away but in badly affected areas the selective use of contact or systemic weed killer is effective and should not damage the paving blocks. Use sparingly and always follow the manufacturer’s instructions.
Efflorescence is a visual effect which can appear on the surface of a concrete product in the form of a white crystalline or hazy deposit. Efflorescence is the leaching out of natural salts from the paving blocks, the sub-base and jointing materials which is completely harmless and will fade and disappear over time.
On dry paving, the efflorescence can be brushed away with a stiff bristled brush, swept clean and rinsed off using a hosepipe. The efflorescence will reocur until the salts are used up and will fade and cease permanently.
See our Efflorescence section for more information.
Damp, shaded areas are more prone to the growth of algae but can be easily dealt with as follows:
Tyre marks and general scuffs will be removed naturally through weathering although scrubbing the affected area with warm soapy water or careful power washing should remove these marks quite readily.
Oil can penetrate the blocks so must be removed a quickly as possible:
Moss does not penetrate the paving and sits on top of any dirt or debris above the paving joint and is easily removed. Scraping and scrubbing is the most effective way of removing moss.
Moss-killing chemicals
There is evidence that some ‘moss-killing’ chemicals can actually discolour paving especially if they contain ferrous sulphate. Use with caution and test on an inconspicuous area first.
Unlike moss, lichen does penetrate into the block surface and is far more difficult to remove than moss or algae. Lichen tends to be in the form of white/grey circular spots but can sometimes be darker in colour. Regular general cleaning will keep lichen growth at bay but should it take hold can be dealt with as follows:
Vigorous scrubbing can scratch the block surface and leave lasting marks and the lichen itself can leave behind marks which cannot be shifted. Therefore, regular cleaning and treatment is the best way to avoid the establishment of lichen and subsequent permanent altering of the appearance of the paving surface.
There are proprietary products for the removal of rust stains on concrete which should be used in strict accordance with the manufacturer’s instructions.
Diluted solutions of hydrochloric acid can be used although this must be used with extreme caution as it etches the surfaces of the paving blocks and poses a personal safety risk if used incorrectly. We advise seeking specialist advice and avoid using acid solutions wherever possible!
Power washers are an excellent cleaning aid but should be used sparingly as repeated exposure to powerful jets can deteriorate the surface of the blocks over time. The jets can remove the jointing sand from between the blocks which must then be refilled and pointed after each use.
Our preferred cleaning method is for sweeping and general cleaning as little and often and the careful use of a power washer only when necessary on a seasonal basis.
Sealants are available for block paving which can be sprayed or brushed on to seal the paving and joints. This skin provides an effective barrier to weeds and stains and can enhance the appearance of the paving. Sealants should be applied by specialists and only after the paving has fully settled.
It is important to ensure that all instances of efflorescence have been exhausted otherwise there is a risk of ‘trapping’ the visible efflorescence under the sealant with no chance of removing it.
At Thomas Armstrong (Concrete Blocks) Ltd we pride ourselves on our high level of customer service across the company. Our friendly staff will be more than happy to help answer any questions you have relating to sales and our products as well as any technical advice you have. Please contact our local office (see offices) near you today!