FAQ’s

222mm x 114mm x 90mm

Standard brick: 55 maxi brick: 33

Standard brick: 110 maxi brick: 66

• Perforated: 2.6-3 kg
• Solid: 3.2-3.4 kg
• Maxi: 3.4 kg

Clay bricks expand fractionally after leaving the kiln (primarily due to moisture in the air) and minute increases in height and width (0.006 percent per annum) continue at a decreasing rate for up to 5 years. Fortunately, with clay products the majority of this expansion happens almost immediately the product leaves the kiln and is exposed to the atmosphere.

Building walls without control joints that exhibit cracking appeared to have expanded only 2mm to 4mm;

In the good old days, all the bricks would be purchased at the beginning of a project and stored for many months before being used. It was thought this gave them an opportunity to harden and “dry out”. Today, purchases are JIT (just-in-time) and the timing from order email to delivery to use is less than a week. The age of bricks in stock will vary considerably from factory to factory and region. Obviously, if the product is in high demand they do not stand too long in the yard before delivery.

There are many sources of movement in walling and paving including ambient moisture levels, temperature, loading and creep, chemical action, ground movement, and settlement. For more information, please download the “Movement of Brickwork” technical paper.

The acceptable water absorption for clay bricks is between 12% and 20%. If you are using engineering bricks the closer you are to the 12% the better the result will be. When the water absorption is too low, i.e. below 12%, it may be difficult to obtain a proper bond between the mortar and the bricks.

Handmade historic bricks; many of which are often found to have an average porosity value of around 35%.

With highly porous bricks there is a danger that they might rapidly absorb moisture from the bedding mortar (particularly in warm weather) causing it to stiffen quickly. This would result in it losing the all-important characteristic of plasticity that would inhibit correct and accurate positioning to line and face-plane and the provision of secure bedding, leading to poor adhesion with attendant negative consequences on aspects of compressive and flexural strengths of the overall walling.

It is important not to confuse ‘porosity’ with ‘permeability’, as they are not the same. Porosity is a measure of the available pore space within a brick. Permeability, however, is a measure of the extent to which air, water, or other fluid can pass through brick, and depends on the pore structure and degree to which these pores constitute a means of transporting from the face to the rear of the brick. A brick can be highly porous, yet impermeable, because if its pores are not interconnected then no water falling on its face can pass through them to the back.

The cost and quality of masonry work are significantly affected by the mortar used. Mortars may account for as little as 7% of the volume of the walls, but the role it plays and the influence it has on performance are far greater than the proportion indicates. Mortar provides a bed for laying; bond units together to give compressive and flexural strength and seals joints against rain penetration.

Four types of building mortar are detailed in SABS 0164.

• COMMON CEMENT – Sand
• COMMON CEMENT – Lime: sand
• COMMON CEMENT – Sand plus mortar plasticizer
• MASONRY CEMENT – Sand (common = Portland)

Cementitious Materials

CEM 1 32.5 (ordinary Portland cement) and CEM 11/A (S, V or W) 32.5 (Portland cement 15) may be used in mortar.

It is not advisable to use CEM 111/A 32.5 (PBFC) unless the mortar sands are of good quality. Mortar with common cement lacks plasticity, may bleed and will be harsh to work with. This deficiency may be overcome by using masonry cement. The use of lime in the mortar mix is beneficial but is difficult to obtain. Masonry cement is readily available.

When sealed in airtight drums, cement remains the same in strength for up to 3 years. When packed in sacks, even under good conditions, deterioration in the strength of the cement will occur, with a prolonged shelf life, for example, 20% loss after 3 months, a 30% loss after 6 months and a 40% loss after 1 year. The arrangements for storing or stocking cement should be such that batches are used in the same order in which they were received. First in – first out.

Sand

Sand for mortar should comply with SABS 1090 and be well graded from 5mm downwards. Sand should be evenly graded and should not contain an excess of dust or other fine material. The use of fine sands, that are more or less uniform in particle size, may contribute to workability, but frequently leads to excessive shrinkage and cracking of the joints. Sands containing a high percentage of clay, tend to give a conveniently plastic mix, but also leads to undue shrinkage.

Lime

Lime used in mortar is hydrated lime (commercial bedding lime) and not quicklime or agricultural lime. Lime give the best results when used with coarse sands. Lime with clayey sands can make the mortar over-cohesive and difficult to use. Lime should not be used with masonry cement.

The use of limes added to cement mortars is recommended as the improved workability and water retentively will lead to superior brick to mortar adhesion, with improved resistance of the brickwork to rain penetration.

Mortar must not be used after it has started to set, which usually occurs about two hours after it has been mixed. One man – particularly if he is a weekend builder – can probably lay a little more than 60 bricks an hour. If you are working on your own or with one assistant, it is better to mix a number of small batches as they are required than to mix a one-bag batch. Do not use too thick a layer of mortar between bricks or blocks; this is wasteful and may lead to cracking.

Mortar class

• Class I: Highly stressed masonry incorporating high-strength structural units such as might be used in multi-story load-bearing buildings; reinforced masonry.
• Class II: Normal loadbearing applications, as well as parapets, balustrades, retaining structures, and freestanding and garden walls, and other walls exposed to possible severe dampness. In practice, Class II mortars are used for most applications.

The amount of water added to a mix must be enough to make the mix workable and plastic

Masonry cement must comply with SANS 50413-1: Strength class 22,5X. The addition of lime to masonry cement is not permitted

MORTAR:

• For laying bricks and blocks in normal applications (SABS Class II)
• To lay 1000 bricks = 3 bags cement + 0.6 cu. m. sand
• 1 Bag of cement to 3 wheelbarrows of building sand

PLASTER:

• For exterior and interior work
• To lay 100sq.m. (15mm thick) = 10 bags cement + 2 cu. m. sand
• 1 Bag of cement to 3 wheelbarrows of plaster sand

Bonding brickwork means the arrangement in brickwork so that the units are tied together to form a solid mass. The load is then evenly distributed along the length of the wall.

There are two methods of lapping:

• The half-brick lap
• The quarter-brick lap, also known as the half bond and the quarter bond.

If bricks are so placed that no lap occurs, the cross joints or perpends are directly over each other, and we have what is known as ‘straight joints’, which must be avoided at all costs.

There are basically three types of bonds used in South African construction and examples of all three can be seen in all towns and cities, – the Stretcher Bond, English Bond, and Flemish bond.

Stretcher bond
(alternate layers of stretchers)

Consists of bricks laid lengthways along the line and mapped. This is by far the most commonly used bond in South Africa. In cavity wall construction this is the most economical bond to employ.

English bond

Consists of alternate courses of headers and stretchers. This bond is believed to be the strongest bond because of the header across bonding. It is usually employed in foundation walling behind the half-brick outer skin, and for retaining walls

Flemish bond

Consists of headers and stretchers in the same course.

Well-made clay bricks should never require wetting before laying except (rarely) under extremely hot and windy conditions.

Pressed or extruded bricks of low porosity should never be wetted prior to bricklaying as they naturally have a significantly reduced water uptake (and almost zero with a Class A engineering brick) that, if wet, would result in the brick retaining a thin film of water on all its surfaces and this would cause it to ‘swim’ on the bedding mortar; and that invariably leads to it both sliding out of face line and sinking out of level. If this happens adjust the water content of the mortar so that it is used as stiff as possible.

Clay bricks purchased from non-accredited sources could have unacceptably high porosity and water absorption rates and might need to be soaked on-site with water before being used.

With highly porous bricks there is a danger that they might rapidly absorb moisture from the bedding mortar (particularly in warm weather) causing it to stiffen quickly. This would result in it losing the all-important characteristic of plasticity that would inhibit correct and accurate positioning to line and face-plane and the provision of secure bedding, leading to poor adhesion with attendant negative consequences on aspects of compressive and flexural strengths of the overall walling.

How much water do I need on older or porous bricks?

The amount of water required to sufficiently dampen the bricks and reduce their absorbency to a level ideal for bricklaying comes with experience, but a brick that has been sufficiently dampened should not leave the hand wet when held.

There is a big difference between a brick that is ‘soaked’ and one that is ‘saturated’. A brick that has been soaked has a high percentage of moisture content but retains sufficient available pore space to still provide the all-essential water uptake, or suction, necessary for it to be properly bedded into, and adhering onto, the fresh bedding mortar. A brick that has been saturated, however, has had all available pore space filled with water. In such a case there is no longer an ability for water uptake, with seriously reduced adhesion, or suction, so the brick ‘floats’ on the mortar; and it can even begin to shed its excess moisture into the bedding mortar that can result in it leaking out of the joint and staining the facework immediately below.

With some new bricks, a further possible problem is that saturation can liberate any integral soluble salts into solution resulting in disfiguring efflorescence (white salts) crystallizing on the face of the bricks.

Cement

Cement is a binder. Similar to flour in a recipe, the purpose of cement is to hold the other materials together. But you can’t just use cement alone. You need the other materials and what you mix with the cement will determine the final product. Cement is made from limestone, calcium, silicon, iron, and aluminum, among other ingredients. This mixture is heated in large kilns to about 2,700°F (1,482°C) to form a product known as clinkers, which roughly resemble marbles. These are ground into a powder and gypsum is added, creating the gray flour-like substance known as cement. When water is added to cement, it triggers a chemical process that allows it to harden. There are many different types of cement, but the type most commonly used in construction is Portland cement.

Concrete

Concrete is a composite of aggregate (such as sand or gravel), cement, and water. The cement makes up from 10 -15% of the total mass of concrete; the exact proportions vary depending on the type of concrete being made. Aggregate makes up more than 60% of a concrete mix — and up to 80% in some cases. The aggregate gives the concrete its mass, and the water activates the cement holding it all together. What proportions of the mix will determine the strength, resistance to freeze and thaw, workability, and how long it takes to harden.

Because it needs low water to cement ratio, it is much thinner when mixed, making it difficult to use as a bonding element. Concrete is used in structural projects and is often reinforced with steel rebar to maintain its structural integrity as the soil beneath it settles. It is best used for support, such as beams, walls, or other building foundations.

Mortar

Mortar is used to hold building materials such as brick or stone together. It is composed of a thick mixture of water, sand, and cement. The water is used to hydrate the cement and hold the mix together. The water to cement ratio is higher in the mortar than in concrete in order to form its bonding element. When mixed, it is a much thicker substance than concrete, making it ideal as a glue for building materials like brick.

Firstly, what is Brickforce?

Brick force is a British brand consisting of two main parallel wires joined by in-line welded cross wires. Main wires are manufactured to a flattened profile to simplify location into the mortar joint without steel build-up problems at lap positions corners/junctions or when used in conjunction with wall ties.

There are various other materials that can be used for brick reinforcement, e.g. Mild steel reinforcing rods and expanded metal. These products and others suitable as brick reinforcement are obtainable in rolls of varying lengths and widths, from your local hardware shop or builder supplies merchants.

Why use masonry reinforcement?

Masonry has excellent compressive qualities and the majority of buildings constructed using this material last for many years with little maintenance. However, masonry has no significant tensile strength and movement caused by substrata changes, moisture or thermal effects can cause cracking.

The use of masonry reinforcement is a very simple and cost-effective way of greatly enhancing the strength and durability of masonry construction by providing both structural and crack control benefits.

It ties the wall together thus providing stability. Over unsupported openings like windows, doors, etc., Brickforce strengthens the wall. If you are building on unstable ground (i.e. there is movement in the ground) it is always good practice to use brick force thus ensuring a very stable wall.

Various types of alternative masonry reinforcement products are also available including mesh and wire.

The gaps on the pavers are 2mm to 6mm, which are to account for both PA and PB pavers so that lines may be maintained. (see the tolerances in the specs on both types of pavers)

The “nibs” technically are only to assist with laying and are not for any structural reason. Most nibs are offset so as not to end up contacting each other, but strictly speaking, the jointing material is designed to diffuse the lateral and vertical forces by transferring them through to the bedding sand and sub-bases layers.

It is highly recommended that the grade of jointing material is different from the bedding sand, to expand in the joints and create the lockup. It must also be vibrated so that it fills the joint to the bottom and in so doing allow the forces to be transferred through. Again, one of the more important issues in the design is the edge restraint which holds the whole system together, and patterns relevant to the user are also critical.

The SACPCMP prescribes the registration of Construction Health and Safety Officers as a specified category in terms of section 18(1) (c) of Act No. 48 of 2000. See the attached document for full guidelines. For additional detail about registration and services, see the website of The South African Council for the Project and Construction Management Professions (SACPCMP) (www.sacpcmp.org.za).

Services of the Health & Safety Officer during the construction phase of a project include:

• Assist with the preparation of a construction health and safety plan
• Confirm necessary documentation was submitted to the relevant authorities
• Attend project planning meetings
• Assessments and approval of contractor(s) health and safety plans
• Attend the contractor’s site handover
• Attend regular site, technical and progress meetings
• Facilitate site health and safety meetings
• Identification of the hazards and risks relevant to the construction project through regular coordinated site inspections
• Establish and maintain health and safety communication structures and systems, distribution of health and safety specific documents to sub-contractors
• Compiling project-specific emergency response and preparedness plans
• Testing the effectiveness of the emergency response plans
• Conduct site safety inductions
• Evaluate the levels of compliance of subcontractors to the project-specific health and safety plan and client specifications through inspections and audits
• Oversee the reporting and investigation of project-related incidents
• Oversee the maintenance of all records
• Participation in management reviews of the health and safety systems
• Use of trends analysis to identify system deficiencies and incident trends, outline relevant improvements
• Incorporation of changes into a health and safety management system
• Review and update the health and safety plan
• Development of technical reports in relation to health and safety issues and communication through presentations to diverse groups of decision-makers

The following recommendations deal with vehicles and associated equipment and their use:

1. High-Pressure washers should not be used on clay brick, as they remove the surface which will result in deterioration over time.
2. Equipment should be purpose-designed to sweep the particular area. If there is any doubt, the vehicle manufacturer should be consulted.
3. Tires should be inflated according to the manufacturer’s recommendations to ensure maximum weight distribution.
4. Polypropylene, not wire, brushes should be used.
5. 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.
6. When sweeping, engine revolutions should be set at the minimum required to maintain vacuum (suction) pressure.
7. Operators, including reliefs, should be trained to vehicle manufacturer’s recommendations and tire and brush pressures should be regularly checked.
8. 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.
9. In new or re-laid areas, the agreement should be reached with the local Highways Authority to allow the pavement to settle and the joints to seal before manual cleaning.
10. When water jetting equipment to wash such areas is used, the jets or handheld 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.
11. The area should be inspected after cleaning to ensure that joints are refilled with jointing sand if necessary.

A refractory brick is built primarily to withstand high temperature, but will also usually have a low thermal conductivity for greater energy efficiency. Usually, dense firebricks are used in applications with extreme mechanical, chemical, or thermal stresses, such as the inside of a kiln or a furnace, which is subject to abrasion from wood, fluxing from ash or slag, and high temperatures.

In the making of firebrick, fireclay is fired in the kiln until it is partly vitrified, and for special purposes may also be glazed.

High-grade fire clays can withstand temperatures of 1775 °C (3227 °F), but to be referred to as a “fire clay” the material must withstand a minimum temperature of 1,515 °C (2,759 °F). Therefore Fire bricks are not needed in braai or fireplaces – a good quality FBX brick will be more than sufficient for the bed of the fireplace, while a standard FBA or NFP brick is sufficient for the sides.

When ordering or specifying clay bricks, ensure the following points are discussed and made known to the suppliers:

• Expected sizes. Not all bricks are manufactured to the standard imperial size of 222mm long x 106mm wide x 73mm high
• The required application e.g. type of building, finish, etc.
• The degree of exposure to weather conditions, closeness to the seas, etc.
• The track record of the preferred brick in the area where you are building
• An undertaking or warranty from the brick supplier that the bricks delivered will be fit for the purpose
• Color expectations in the case of face bricks or exposed brick areas
• The acceptable levels of breakage during delivery to the site
• The brick manufacturer registered with the Clay Brick Association of SA.

To avoid color banding it is highly recommended that face bricks are taken from a number of different packs and carefully blended during building operations.

Properties that require consideration when buying or specifying clay brick are:

• Compressive strength (varies from 7MPa to 50MPa)
• Water absorption (face brick up to 10%, NFP up to 16%)
• Modulus of rupture – strength in bending
• Moisture expansion – important when detailing long walls
• Initial rate of absorption: This affects the development of the bond between the mortar and the brick. Bricks with high rates of absorption (often lower quality) may require pre-wetting well before laying to prevent absorbing excess water from the mortar mix. Trial and error experiments when bricks arrive on-site will determine the need to pre-wet bricks.

Firebricks (or refractory bricks) are totally over-specification in a domestic fireplace or braai. They are also expensive and not easily available. Refractory Bricks are normally rated from around 1600’C upwards – a braai will never reach this heat.

Any clay face brick or semi-face (fired) brick can be used for a braai. Face bricks are fired to around 1000 – 1250’C to stabilize their structure, and they have a high thermal mass which helps them insulate for heat. The heat in the fireplace would need to be higher than this to have any effect on the brick.

Concrete bricks or any regular concrete product made with Portland cement cannot stand up to high temperatures and will disintegrate at the temperatures required by a pizza oven or braai.

With excessive heat, cement and mortar between the bricks can crumble. Build the outer skin of the sides of the braai/fireplace with a standard mortar mix (1 bag cement : 3 Barrows Sand) with brick force and cavity ties. Build the inner skin with a well-burnt clay face brick (FBX) using a weaker mix (1 bag: 6 Barrows Sand) – this allows more joint movement and reduces cracking from heating.

The base is normally the area that gets the most heat as the fire is resting on this. Here a clay paver or solid clay brick should be laid on a sand bed. Do not cement bed or grout – it must have some movement to allow for heating and cooling expansion/contraction. The bricks/pavers at the opening to the braai can be grouted in to form an edge restraint. The fire generally is never built right at the opening so they don’t get as much heat. Grouting these prevents the pavers behind from falling out / working loose. It acts like a kerbing.

For the sides or a raised bed, you can use an air-set refractory cement (as opposed to a fire-set refractory cement), and minimize the joint space between the bricks – use “buttered joints” i.e. have the bricks very close together.

The standard imperial size is 222mm long x 106mm wide x 73mm high with a mass of between 3.0kg and 3.5kg.

Two important criteria determine this size. First, it is the ideal width for the human hand to lift and place in position with minimum strain and secondly, it satisfies the need for bricks to be modular in terms of BOND patterns. Thus there is an approximate arithmetic relationship of length to width of 2:1 and in length to the height of 3:1, which allows for bonding in any direction.

However, every manufacturer can offer and range of sizes and dimensions to suit different applications.

Superbricks & Maxis
“Superbricks” come in a range of non-standard, large sizes that lower material costs, use less mortar and have fewer joins per square metre. With 140mm wide bricks, one can build a single leaf wall that meets SABS10400XA for a single leaf wall.

For winter rainfall coastal regions, manufacturers have developed brick formats that are narrower and taller than the imperial brick to reduce labour and costs of double skin cavity wall construction.

Fewer bricks per m² afford savings in a mortar and accelerate the speed of construction consequent to fewer bricks per m² laid. But as this is still a double leaf wall, the property owner still enjoys all the benefits of double-leaf cavity clay brick walling

Special Shapes
A range of special shapes is available to enhance the aesthetic detailing of buildings and landscaped areas. The most common specials available are the cants and the bullnose bricks although special shapes can also be manufactured to specification. It is advisable to discuss your requirements with your supplier.

Full Question
Referring to SANS 1575 Burnt clay paving units Modulus of rupture 7.6.11

• c) a mechanism capable of applying a force uniformly along with the cylinder and of increasing the stress at a rate of 1MPa +- 0.2MPa per second.

What would be the load rate in Newton’s per second for a sample 200mm long x 100mm wide x 50mm thick?

Answer
1 pascal = 1[N/m²] therefore 1Mpa = 1 000 000 [N/m²] or for ease of calculation 1 MPa = 1000[kN/m²]

Martin Hughes
Corobrik

The question continues:
“The walls are 3m high by 4.5m wide by 0.2m thick, and supported at each end of the 4.5m I believe this will have a fire rating of 240 minutes? How do I support the wall for strength against the wind? Are steel wire wall ties sufficient? “

ANSWER

You do not need a special type of brick such as fire brick. I suggest a double skin masonry wall in standard imperial clay brick, with each leaf 106 mm in thickness. This will yield an overall wall thickness (unplastered) of 212 mm which will have a nominal fire rating of 240 minutes.

I would recommend supporting each 4-meter length of the wall with a 340 x340mm brick pillar at each end, as well as using wire ties (brick force) as suggested.

Chris Dickinson
Corobrik

The amount of water added to a mix must be enough to make the mix workable and plastic. Use cement that has the SABS mark (SABS ENV 197-1). Masonry cement that complies with SABS ENV 413-1; strength class 12.5 or higher may be used for mortar and plaster.

A builder’s wheelbarrow usually has a capacity of 65 liters

LARGE BATCHES

MORTAR:

• For laying bricks and blocks in normal applications (SABS Class II)
• To lay 1000 bricks = 3 bags cement + 0.6 cu. m. sand
• 1 Bag of cement to 3 wheelbarrows of building sand

PLASTER:

• For exterior and interior work
• To lay 100sq.m. (15mm thick) = 10 bags cement + 2 cu. m. sand
• 1 Bag of cement to 3 wheelbarrows of plaster sand

SMALL BATCHES
(Measure with a container such as a bucket, drum or tin)

MORTAR:

• 1 unit of mortar to 5 units of mortar sand

PLASTER:

• 1 unit of mortar to 5 units of plaster sand and stone

Full Question:
Do I need special refractory tiles or “fire bricks” for an indoor fireplace or outdoor braai? How do I make sure the bricks don’t crack and crumble from the heat?

Answer:
Clay Bricks are fired at high temperatures to stabilise their structure, and have a high thermal mass which helps them insulate for heat. In a domestic fireplace or braai they are really a total “over specification”. Refractory Bricks are normally rated from around 1600’C upwards. They are expensive and not easily available.

A braai will never reach this kind of heat and all facebricks are fired to around 1000 – 1250’C. The heat in the fireplace must get higher than this to have any effect on the brick. Generally your mortar joint will fail before the brick. What I always suggest to people is the following.

Build the outer skin of the sides of the braai/fireplace with a standard mortar mix (1 bag cement : 3 Barrows Sand) with brickforce and cavity ties. Build the inner skin with a well burnt clay face brick using a weaker mix (1 bag : 6 Barrows Sand) – this allows more joint movement and reduces cracking from heating.

Concrete bricks or any regular concrete product made with Portland cement cannot stand up to high temperatures and will disintegrate at the temperatures required by a pizza oven or braai.

With excessive heat, cement and mortar between the bricks can crumble. I recommend you use an air-set refractory cement (as oppose to a fire-set refractory cement), and minimize the joint space between the bricks – use “buttered joints” i.e. have the bricks very close together.

The heat to the walls of a grill is not that high (compared with the floor where the fire is built or the ceiling of a pizza oven) so ordinary tile cement can be used to adhere tiles.

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 and in shade.

Oil stains

Oil does not penetrate readily into clay pavers, but if the oil is spilled 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 color of the clay paving.

Bitumen stains

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.

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 colored mortars, specialist advice from the colored 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.

A burnt clay face brick 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 the industry and these will 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 the 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

Brick is porous, so paint sinks into all the grooves on the surface. It is impossible to scrape like wood, and interior walls cannot easily be water- or sand-blasted. Chemical and gel masonry strippers are the solutions for inside walls; and while the process of stripping the brick is not complicated, it involves multiple applications of stripper and lots of scrubbing, making it a time-consuming project.

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.

1. Put on safety goggles, a face mask, and work gloves to avoid coming into contact with the stripper chemicals or fumes.
2. Brush the masonry paint stripper generously over the brick wall with the brush, starting with one corner and working outward and downward. Reposition the ladder to work on the top of the wall first all the way across; then continue working on the next section until the entire brick has been covered in stripper.
3. Wait the amount of time specified by the manufacturer. Then begin at the top of the wall again and scrub the masonry paint stripper off with a stiff-bristled brush. Paint will come off in chunks and flakes; continue to wear the protective gear. Scrub the entire wall with the brush, removing as much of the paint as possible.
4. Wash the brick wall with rags and warm water to remove clinging paint and the stripping compound. Allow it to air-dry.
5. Reapply another layer of masonry paint stripper to remove stubborn paint. Allow it to sit on the brick and scrub again. This step may have to be done several times to get most of the paint off the brick wall. Repeat the rinsing process to remove the stripper.
6. Spray the stripped brick wall with white vinegar, and scrub off any remaining paint residue with a clean brush. Rinse with water.

Pressure washing should not be used as it can quickly erode the surface of bricks. Some caustic chemical solutions can cause surface failures or can change the color of old bricks. Rapid deterioration is then likely to occur, resulting in the need for major repairs

It is common to find growths such as algae, lichens, liverworts, and moss growing on hard surfaces. Contrary to popular belief, they do not damage what they are growing on but can cause patios, drives, paths, and steps to become slippery.

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 and in shade.

Non-chemical control

• Dislodge moss from between paving by running a sharp knife along the cracks. Alternatively, use a block paving brush with a long handle, narrow head, and wire bristles for effective cleaning without stooping
• A pressure washer will remove moss and algae effectively. However, use this method with care in areas where drainage is unsatisfactory as the extra water could exacerbate damp problems. Always wear goggles when using a pressure washer.
• Brush hard surfaces with a stiff broom on a regular basis to help prevent growths from taking hold. Raking loose surfaces such as gravel helps to keep these areas free of both moss and weeds
• Prune overhanging plants to improve air flow – this will allow the drying effects of sun and wind to reach the site
• Ensure surfaces slope slightly to prevent standing water
• Improving drainage in the surrounding area will also help to deter growths. Dig out shallow channels along the edges of paths, patios and drives and fill with coarse gravel to absorb run off water
• Fork over beds close to damp surfaces to maximise drainage and water absorption
• Only pave areas essential for access. Choose permeable paving when constructing new hard surfaces and keep drains clear of leaves and debris
• Surface finishes that are raised to give grip in wet weather are ideal for shady spots. Spreading coarse sand over garden steps is another simple anti-slip solution

Mark Hunter-Smith of Algoa Brick advises:

“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. Sealing traps moisture in the bricks and wall and causes softening and failure of the mortar. In most older buildings you will be able to see that the bricks do not fail, it is the mortar that crumbles or splits.

“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 tire abrasion etc. It has no roof overhang to protect or vertical walls for the rain to run down i.e horizontal surface taking a 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 rainwater pooling occurs, and also surface can become rather slippery.

“I would suggest rather a good clean with a high-pressure setting of a garden hose using industrial type soap like Teepol. If dirt very stubborn a weak acid cleaner can be used.”

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 1960s can be substantially affected by salt deterioration. This is more prevalent in the exposed location but buildings located 2-3 kilometers 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 is 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 the brickwork will accelerate. It is not possible to prevent the surface delamination of bricks.

We have however noticed that the higher temperature 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 the ground level due to rising dampness 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 plaster the ground floor brickwork and paint them to a chosen color, 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 color 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. Complete rusting of the wall ties will allow the external brickwork to bow out as it is unrestrained and in extreme cases can cause a complete collapse of the external skin of the brickwork. In corrosive environments, stainless steel wall ties are recommended during construction.

Clive Archer
Managing Director

Crammix Bricks