Maintaining Clay Bricks

How do I remove oil and bitumen stains?
  • Oil stains
  • Bitumen stains
Oil does not penetrate readily into clay pavers, but if oil is spilt on the pavers, the spillage should be removed promptly with an absorbent material, such as paper towels. The oil should not be wiped up; otherwise this will spread the contamination on the surface of the paver. Steam cleaning can be used on clay pavers to remove such staining, but if this is unsuccessful an emulsifying de-greaser should be employed. Brush with plenty of water to safe disposal. An alternative cleaning method is to brush the area with a strong detergent and hot water. This will not affect the colour of the clay paving.
Bitumen does not penetrate readily into clay paving. The best method of removal is to leave the bitumen until it has cooled. A paint scraper or a similar mechanical device can then often remove it. If it is particularly resistant, the use of ice to make the bitumen even more brittle may be required, prior to scraping it from the paving. Any residue should be removed with a scouring powder and finally the whole area rinsed with clean water. Certain proprietary cleaning agents are available to remove bitumen, but these should be tested on an inconspicuous area of paving first.
How do I remove cement stains?
Remove large deposits with wooden implements to avoid damaging the paver surface. Following the pre-wetting of the area, treat the residue of mortar by careful application of a dilute hydrochloric acid solution or a proprietary cleaning solution. The application of the acid breaks down the cementitious components but is not damaging to clay pavers. As with all cleaning procedures a rinsing operation should be carried out shortly after application, and care taken to dispose of run off solutions safely. If the above method is not successful with coloured mortars, specialist advice from the coloured mortar supplier should be sought. On the rare occasions when a vanadium efflorescence is present, hydrochloric acid based cleaners must not come into contact with the efflorescence, otherwise a dark stain will result which will become fixed on the surface.
Are clay bricks petrol & diesel resistant?
A burnt clay facebrick type product is resistant to petrol and diesel. For many years Caltex specified only clay pavers for their garage forecourts for this reason (Tarmac was never used as petrol and diesel attack it) Although petrol can stain bricks, they are easy to clean. Acid resistant clay tanks are common in industry and these willl also cope best with petrol and diesel. We would suggest a specialized mortar and possibly a lining is used. There are many specialist suppliers – just search the net! The acid and chemical resistant clay bricks are featured products in various construction and refractory applications and are available in various shapes and types such as Arch Bricks, Tapper Bricks, Sleeves, Tongue & Groove Bricks.

Chemical resistant clay bricks are used in following application areas:
  • Chemical plants: Dyes, Intermediates, Acids and Alkalies
  • Fertilizer Plants
  • Thermal power plants for chimney construction
  • Petrochemicals and refineries
  • Pharmaceuticals etc
  • Galvanizing Plants
Help – I need to remove graffiti from my brick wall?
Both paint and graffiti are difficult to remove. Fresh wet paint should be soaked up with an absorbent material without wiping the paint, as this will spread the stain. It should then be treated with a suitable solvent, such as white spirit, and then the area washed with a de-greasing agent taking care in the disposal of the run-off material. With dried paint, the paint should be scraped off as far as possible and then a paint remover to BS3761 (4) should be applied.
How can I remove moss & algae from bricks?
Moss, lichens and algae should not grow on clay bricks unless the area is heavily shaded, is under trees, or is not laid to an adequate fall. If such growth does occur and is considered undesirable then the area should be treated with a proprietary moss killer used in accordance with the manufacturer’s instructions. Such products take some days to be effective and work best when applied during a spell of dry weather. Any thick growths should be scraped off first and the chemical treatment well brushed in. Some treatments leave a residue to discourage the re-growth of the moss and algae, but this will only be of limited value if the paving remains damp andin shade.
What sealer will restore my paving?
Mark Hunter-Smith of Algoa Brick advises: “Firstly any form of sealant or dressing on a brick automatically turns a maintenance free product into one that has to be maintained as the sealer will weather and or peel off over time. The only time this has limited success is internal feature walls that are protected from the elements. “Applying a sealer to an external paving situation is probably the hardest to do as it is totally exposed to weather as well as car tyre abrasion etc. It has no roof overhang to protect or vertical walls for rain to run down i.e horizontal surface taking full pounding. I do not think a sealer will last very long in this application especially in the high wear areas which can create a patchy type finish. Also a sealer makes the paver waterproof so rain water pooling occurs and also surface can become rather slippery. “I would suggest rather a good clean with a high pressure hose using industrial type soap like Teepol. If dirt very stubborn a weak acid cleaner can be used.”
How do I prevent salt damage at the coast?
Please refer to our Technical guides under `SALT ZONES` and salt erosion of clay bricks. If you have a property situated on the beachfront there is usually some degree of deterioration taking place! All bricks are porous and will absorb salt, and many factors are at play so it is impossible to say how long it will be before deterioration of the façade begins. The softer lime mortar used in external brickwork prior to the 1960’s can be substantially affected by salt deterioration. This is more prevalent in the exposed location but buildings located 2-3 kilometres from the sea can also be affected.
The mortar becomes soft and powdery. More recent Calcium Silicate face bricks can still suffer from surface delamination. This occurs as the salt crystals adhere to the brickwork and are absorbed into the bricks. During rain the crystals will expand and then push the outer surface of the brickwork away. Once the hardened surface of the brickwork is lost, then the rate of deterioration of brickwork will accelerate.
It is not possible to prevent the surface delamination of bricks. We have however noticed that the higher temperatured bricks like steel blues are holding out better than the reds/yellows and browns.

Smoother textures are better than others at resisting the attack in severe zones. In many cases, the problem is concentrated at ground level due to rising damp or minerals added to soil as fertilizer. The location does give easy access to undertake repairs. The best solution in my opinion is to remove all the flakes from the damaged bricks, brush them down and then to plaster the ground floor brickwork and paint to a chosen colour, which would best suit your building.
A well plastered smooth finished wall with waterproofing additives would prevent the ingress of salt and would therefore not deteriorate in the same way. Only normal painting at intervals will be required. If the decision is to replace the brickwork with a new face brick finish, then it could be done but we would then suggest a low porosity brick with a smoother surface (not rustic textured which holds more salt). This would lengthen the life of the brickwork although it is impossible to say how long before the same type of damage occurs again. Individual bricks can be replaced as well, but this is an untidy solution, as the new bricks will look odd (another colour and size) and it will take an enormous amount of time.

The third concern after mortar and bricks, is the rusting and deterioration of the wall ties, which secure the external skin of brickwork to the main building. With complete rusting of the wall ties, this will allow the external brickwork to bow out as it is unrestrained and in extreme cases can cause complete collapse of the external skin of brickwork. In corrosive environments, stainless steel wall ties are recommended during construction. Clive Archer Managing Director Crammix Bricks
Can I use a cleaning machine on paving?
The following recommendations deal with vehicles and associated equipment and their use:
  • Equipment should be purpose designed to sweep the particular area. If there is any doubt, the vehicle manufacturer should be consulted.
  • Tyres should be inflated according to the manufacturer’s recommendations to ensure maximum weight distribution.
  • Polypropylene, not wire, brushes should be used.
  • Sweeping brush pressures should be set to the minimum required to suit the particular task, i.e. surfaces swept regularly will require a lesser setting than those swept infrequently or those covered with heavy deposits.
  • When sweeping, engine revolutions should be set at the minimum required to maintain vacuum (suction) pressure.
  • Operators, including reliefs, should be trained to vehicle manufacturer’s recommendations and tyre and brush pressures should be regularly checked.
  • Advice should be given to operators that, when equipment is stationary or left unattended, suction, brush rotation and water jetting equipment should be switched off to avoid the risk of damage to the area below the stationary equipment.
  • In new or re-laid areas, agreement should be reached with the local Highways Authority to allow the pavement to settle and the joints to seal before manual cleaning.
  • When water jetting equipment to wash such areas is used, the jets or hand held lance should be directed at the surface at an angle not greater than 30o and across the diagonal (i.e. not parallel to joints) using a suitable detergent solution.
  • The area should be inspected after cleaning to ensure that joints are refilled with jointing sand if necessary.
Walling Requirements of Low Cost Housing (Preventing Mould Growth)
Walling Requirements of Low Cost Housing in the Southern Cape Condensation Problem Area and the Need to Prevent Mould Growth

Introduction to problems around walling in the SCCPA
The Southern Cape Condensation Problem Area (SCCPA) is that area stretching from Malmesbury and Ceres in the West and following South of the coastal mountain ranges and escarpment though the Western Cape Province into the Eastern Cape Province and up to and including Port Alfred in the East (See Annexure C). This area is prone to prolonged periods of cold and rainy weather. Building elements (particularly concrete block walls and fibre-cement roofs) are likely to become waterlogged by rain ingress and interior surface condensation to the extent that it may be possible that mould growth occurs on the damp surfaces. Respiratory health problems, including TB, have been reported and connected to the prevalence of such mould growth, and the associated airborne spores carried in homes in this region. A further issue is the health risk resulting from the poor state of repair and inadequate design of much low cost housing in the Western Cape. This is reported to the Human Settlements Portfolio Committee of the Cape Town Metropolitan Council dated August 2011.
Condensation Risk in Relations to Walls
The TEMMI report to the Agrément Board of South Africa ‘Defining new condensation boundaries in the Southern Cape’ concludes that the major condensation within the low cost housing is that which is occurring on the underside of roofs, and that the condensation occurring on walls is relatively minor. The report states that the main areas in houses where mould occurs are those areas adjacent to taps, leaking pipes in kitchens and bathrooms, and around cracks in the walls. Mould is reportedly not found under-roof, and not often on walls. The mould growth in walls will be a result of structural cracks and consequent rain penetration, in the view of the authors. From these and other comments it might be presumed that the condensation is occurring preferentially on the underside of the roofs, and that which may be occurring on the walls is within the interstitial wall cavities and is not visible.
What is the white, powdery substance on my bricks and how do I remove it?
Efflorescence is a powdery deposit of salts which forms on the surface of bricks and paving. It is usually white but efflorescence can be yellow, green or brown. Efflorescence does not in any way influence the structural strength of clay bricks or pavers. Roman buildings that have been standing for 2 000 years can show efflorescence A temporary efflorescence is particularly common on new brickwork and paving as soluble salts are dissolved and transported to the surface of the brickwork and paving by water. The efflorescence on new well fired brickwork and paving may be unsightly, but it will not cause damage unless the brickwork and paving are under-fired or soft-fired, in which case serious efflorescence can cause flaking of the surface of the brick or paver. Efflorescence can occur from a variety of sources. Besides the brickwork, soluble salts can originate from the sand, mortar and the water used. Ground waters that are naturally salt-bearing can be drawn into the base of the brickwork and paving.
The best removal method is simply to brush off the deposit with a stiff dry bristle brush after the wall has dried out. Collect the removed salts with a dust pan or a vacuum cleaner to prevent the salts re-entering the brickwork. Wetting the wall by methods such as hosing usually dissolves efflorescence back into the brickwork, allowing it to reappear again when the wall dries out. Acid or alkaline treatments are not recommended as they do more harm than good because they add to the total salt content. Dries V of Cermalab The efflorescence can be removed by washing with a high pressure washer, some builders pre wet the surface with a dilute solution of pool acid prior to using the high pressure washer. Ivan Freeman of Rheebok Stene