STONE
Stone refers to natural rocks after their removal from the earth crust. The familiar stone types that used today are identified through four categories for remodeling which are sedimentary, metamorphic, igneous and man-made. Classification depends on the process by which they were produced within or on the earth's surface.

Sedimentary rocks are produced by the weathering and erosion of older rocks. In the earliest geological time, these would have been the original igneous rocks but subsequently other sedimentary and metamorphic rocks too will have been reworked. Weathering action by water, ice and wind breaks the rocks down into small fragments which are then carried by rivers and sorted into size and nature by further water action. Most deposits are laid down in the oceans as sedimentary beds of mud or sand, which build up in layers, becomes compressed and eventually are cemented together by minerals. They were bonded through millions of years of heat and pressure.

Sedimentary rocks

For thousands of years, little pieces of our earth have been eroded, broken down and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of the other. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock.

While for the metamorphic stone, it is originates from a natural change from one type of stone to another type through the mixture of heat, minerals and pressure. The change may be development of a crystalline formation, a texture change, or a colour change. Clay is metamorphosed to slate, limestone to marble and sandstone to quartzite.

metamorphic stone

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you exam metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.

Igneous rocks are the oldest, having been formed by the solidification of the molten core of the earth or magma. They form about 95% of the earth crust which is up to 16km thick. Igneous stones are mainly formed through volcanic material such as magma. Underneath the earth surface, liquid magma cooled and solidified. Mineral gases and liquids penetrated into the stone and created new crystalline formations with various colours. If the magma stays underground, cools slowly and makes big crystals, it is called intrusive igneous rock. Extrusive igneous rock is made when magma comes to the Earth’s surface in the form of lava and then cools and hardens. Since lava cools quicker, the crystals of surface igneous rock are smaller. Solidification slowly within the earth crust produces plutonic rocks while solidification rapidly at the surface produces volcanic rocks. Slow cooling of plutonic rocks allowed large crystals to grow which are characteristic of granites. Volcanic rocks such as pumice (grey volcanic rocks) basalt (dark volcanic rocks) are fine-grained and individual crystals cannot be distinguished by the eye.

Igneous rocks

Igneous rocks are called fire rocks and are formed either underground or above ground. Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped in small pockets. As these pockets of magma cool slowly underground, the magma becomes igneous rocks.

Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma appears above the earth, it is called lava. Igneous rocks are formed as the lava cools above ground.

The last type of stone which familiar use nowadays is man-made stone. Man-made stones are derived of unnatural mixtures such as resin or cement with the additive of stone chips.

The example of sedimentary stones is limestone, sandstone, and fossil stone. Limestone mainly consists of calcium carbonate, either crystallised from solution as calcite or formed from accumulations of fossilised shells deposited by various sea organisms. There are various type of limestones such as oolitic limestone, organic limestone, crystallised limestone, dolomitic limestone. It does not show much graining or crystalline structure. It has a smooth granular surface. Varies in hardness. Some dense limestone can be polished. Common colours of limestone are black, gray, white, yellow and brown. It is more likely to stain than marble. Limestone is know to contain lime from sea water. Sandstone is a very durable formation of quartz grains ( sand ). It usually formed in light brown or red colours. Categorized by the most popular and stone bonding agents such as calcium carbonate, silica, iron oxide and dolomite produce calcareous, siliceous, ferruginous and dolomitic sandstones. Depending upon the nature of the original sand deposit, the sandstones may be fine or coarse in texture. Sandstones are generally frost-resistant. Fossil stone considered a limestone that contains natural fossil such as sea shells and plants. It usually a cream or reddish colour. Fossil stone is formed through the accumulation of calcite from hot springs. It contains lots of holes that were formed from water flowing through the stone. These holes are often filled with synthetic resins or cement. 

Marble, slate, quartzite are metamorphic stone. Marble is metamorphosed limestone in which the calcium carbonate has been recrystallised into a mosaic of approximately equal-sized calcite crystals. It is a recrysrallized limestone that formed when the limestone softened from heat and pressure and crystallized into marble where mineral changes occurred. Some limestones which can be polished are sold as marble but true marble will not contain any fossilised remains. Marble is attacked by acids. The main consistency is calcium and dolomite. Ranges in many colours and is usually heavily veined and shows lots of grains. The hardness rate of marble is from 2.5 to 5 MOH scale. Marble is classified into three categories: Dolomite ( if it has more than 40% magnesium carbonate), Magnesian ( if it has between 5% and 40% magnesium carbonate) , and Calcite ( if it has less than 5% magnesium carbonate ). Slate is derived from fine-grained sand-free claysediments. Slate is strong, acid- and frost-resistant, lasting up to 400 years as a roofing material. Quartzite is also metamorphosed sandstone. The grains of quartz are recrystallised into a matrix of quartz, producing a durable and very hard wearing stone used mainly as a flooring material.

Granite and basalt are igneous stone. Granite primarily made of Quartz, Feldspar, and Potassium. Colours of granite include grey, pink, black, blue, green, red, yellow, brown and contain very little calcite. It provides a heavy crystalline and granular appearance with mineral grains. It is very hard material and easier to maintain than marble. Because most of tvhe granites are hard and dense and thus form highly durable building materials, virtually impermeable to water, resistant to impact damage and stable within industrial environments. Yet, it is still porous and will stain. There are different types of granite depending on the percentage mix quartz, mica and feldspar. Black granite is known as an Anorthosite. It contains very little quartz and feldspar and also has a different composition that true granite. Granite is available for flooring and for hard landscaping including pavings and kerbs. Polished granite is also used as a kitchen countertop material due to its strength, durability and high- quality finish. Basalt is a fine-grained stone nearly as hard as granite. It can be melted at 2400^o C and cast into tile units which are deep steel grey in colour. Annealing in a furnace produces a hard virtually maintenance-free shiny textured surface.

Man made stone include Terrazzo, Agglomerate or Conglomerate and Cultured or Faux Marble. Terrazzo is marble and granite chips embedded in cement composition while Agglomerate or Conglomerate is marble chips embedded in coloured resin composition. Cultured or Faux Marble is a mix of resin that are painted or mixed with a paint to look like marble which consider a man-made stone.

There are some main agencies which causes the deterioration of stone such as soluble salt action, atmospheric pollution, frost, corrosion of metal components, poor design or workmanship. 

Soluble salt action

If moisture containing soluble salts evaporates from the surface of stonework, then the salts will be left either on the surface as white efflorescence or as crystals within the porous surface layer If the wetting and drying cycles continue, the crystalline material builds up within the pores to the point at which the pressure produced exceed the tensile strength of the stone, causing it to crumble. The more porous stones such as limestone and sandstone, are susceptible to soluble-salt action.

Atmospheric pollution

Stones based on calcium carbonate are particularly vulnerable to attack by acid atmospheric pollutants. Sulfur dioxide in the presence of water and oxygen from the air produces sulfuric acid which attacks calcium carbonate to produce calcium sulfate. Limestone and calcareous sandstones are vulnerable to attack.

Frost

Frost damage occurs in the parts of a building which become frozen when wet. Frost causes the separation of pieces of stone but it does not produce powder as in crystallisation attack. Generally, limestone is more vulnerable to frost damage than sandstones. Marble, slate and granite used in a building are normally unaffected by frost due to their low porosities.

Corrosion of metal components

Rainwater run-off from copper and its alloys can cause green colour staining on limestones. Iron & steel produce rust staining which is difficult to remove from porous stones. Considerable damage is caused by the expansion of iron and steel in stonework caused by corrosion. All new and replacement fixings should normally be manufactured from stainless steel or non-ferrous or non-ferrous metals.

Fire rarely causes the complete destruction of stonework. In the case of granite, marble and most sandstones, the surfaces may be blackened. Limestones are generally unaffected by fire, although the paler colours may turn permanently pink due to the oxidation of iron oxides within the stone. 

Generally, large plants should be removed from old stonework. However, creeper and similar species are not considered harmful.

External granite, marble and slate claddings require regular washing with a mild detergent solution; in particular, highly polished external marble should be washed at least twice per year to prevent dulling of the surface. Limestone, which is not self-cleaned by rainwater, should be cleaned with a fine water spray and brushing, removing deposit from the surface. Sandstone is usually cleaned mechanically by abrasive blasting or chemical cleaning.

Stone is preserve by coatings such as silicone water repellents should only be applied to stonework following expert advice and testing. Silicone treatment may in certain cases cause a build-up of salt deposits behind the treated layer, eventually causing failure. Silicone treatment should not be applied to already decayed stone surfaces.

BRICKS

BRICKS

“Nothing remarkable about a brick, is there? A brick is a brick so far as most people are concerned. Ans it is not a very beautiful thing, is it? But what you can do with it!'

-Frank Lloyd Wright

Brick is one of the oldest building material in the world, the history of brick spans thousands of years. Brick is describes as a molded, rectangular block of clay baked by the sun or fired in a kiln until hard and used as a building and paving material. It is easily molded and extremely durable due to its' unique molecular quality of clay. According to BS3921, brick is a walling unit designed to be laid in mortar not more than 337.5mm long 225mm wide and 112.5mm high. Bricks is made by four materials: burned or fired clay, calcium silicate, dense concrete, lightweight concrete. The main use of bricks are as units in mortar to form walls and piers.

Appearance

Bricks may vary in color between batches and depends on mineral content and the presence of metallic oxides. Integral color results directly from the characteristics of the various clays; natural colors results of iron oxide, chalky clays and others. Brick remain stable and color-fast and do not need to be rendered or painted. The colour of brick also influenced by high temperature was during burning. Bricks are generally red, but an increase in temperature can change them to dark red, purple, brown or grey. Bricks containing silicate depend on the colourant used. The colour and place of manufacture is reflected in the brick names. Clay brickwork is most commonly used uncoated to display the richness and texture of the material. 

Structural Strength

Clay bricks may have strength up to 180N/mm². The high compressive strength of clay bricks has been show from single-storey house to massive public buildings and enormous bridges and viaducts. Clay brickwork walls can support relatively high loads. Clay brickwork is commonly in four-storey construction and it can act as loadbearing wall for high rise building.

Type	Compressive strength, N/mm²
CLAY BRICKS Clay bricks – range Loadbearing common bricks Engineering Class A Engineering Class B	4-180 7-60 70.0 50.0

              Approximate compressive strength ranges of bricks

Durability

Brick is strong and long lasting. Many ancient building build by brick is still standing such as The Great Wall of China. It will not rot, dent, tear and no need painting, never eaten by termites and hence have a low maintenance requirement. Other material, such as artificial stucco, cost about the same as brick but less durable and so it require greater maintenance and upkeep.

Thermal Mass

A brick house can maintain a relatively stable temperature for a long period, and remain cool in summer and warm in the winter in a building. Thermal mass is a property that enable heavy, dense material to absorb, store heat and then release significant amount of heat. This delays and reduces heat transfer and causes it energy efficient and can reduce the quantity of power plants required.

Insulation

Clay brickwork, combined with internal and external air films and a cavity, has moderate thermal resistance. The thermal resistance of clay brick veneer or cavity walls can be greatly enhanced by adding foil or bulk insulation. Wall insulation should be appropriate detailing to avoid thermal transfers by bridging through window openings or by convection through leakage.

Sound Insulation

Bricks provide excellent sound insulation, particularly for low frequency noise. Brick absorbs noise which gives an acoustic advantage over other material. Well constructed brickwork offers insulation against airborne sound n ratio to its density and thickness although this is seriously reduced by bricklaying which leaves small even paths for sound through a wall.

Fire Resistance

Brick is an excellent medium for fire resistance. It does not burn when exposed bushfire and can help protect the more combustible items inside a building. The primary ingredient of brick, clay is a non-combustible material which can be fired to around 20008F. Both National Institute of Standards and Technology and BIA conducted seperate fire tests and conclude that:

• Nothing outperforms good old-fashioned brick – even a hollow thinner brick attains one hour
• Today's “advanced” materials – especially vinyl, engulfed by flames within minutes.
  

Design Of Clay Brickwork For Fire

Fire resistance period (minutes)	Required material thickness for insulation (mm)	Maximum slenderness for structural adequacy (mm)
30	60	25
60	90	22.5
90	110	21
120	130	20
180	160	18
240	180	17

Water absorption

Bricks resist the penetration of of water but they are not completely waterproof Some moisture may even soak through the mortar joints. Water absorption varies from 3%-30% .

Designation	Class	Minimum average strength, N/mm²	Maximum average water absorption after 5 h boiling (% by weight)
Engineering bricks – BS 3921	A B	70.0 50.0	4.5 7.0
Bricks for damp-proof courses - BS3921	DPC1 DPC2	5.0 5.0	4.5 7.0
All others - BS3921		5	No requirements

Strength and water absorption requirements for clay bricks

Vermin resistance

Clay brickwork consists of dense inorganic materials that do not harbour vermin, Termite resistance may be achieved in a variety of ways, including proprietary termite barriers developed for use with clay brickwork.

Environmental impacts

Clay brick manufacture uses energy but the investment of embodied energy is repaid by the longevity of the material. Clay brick homes have a long life, low maintenance requirements and highly recyclable making them a potentially sustainable form of construction. Clay bricks can often be reclaimed for re-use when a building is demolished. After cleaning they can either be directly re-used as bricks again, or they can be crushed for making path and road surfaces. Because of their inert, organic nature, another uses for crushed clay bricks is as part of the mix for growing medium of extensive green roofs.

______________________________________________________________

The History of Bricks and Brickmaking

Bricks are one of the oldest known building materials dating back to 7000BC where they were first found in southern Turkey and around Jericho. The first bricks were sun dried mud bricks. Fired bricks were found to be more resistant to harsher weather conditions, which made them a much more reliable brick for use in permanent buildings, where mud bricks would not have been sufficient. Fired brick were also useful for absorbing any heat generated throughout the day, then releasing it at night.
The Ancient Egyptians also used sun dried mud bricks as building materials, and in the villages and smaller towns of Egypt the houses to-day are built of bricks similar to those that were used about 6,000 years ago, evidence of which can still be seen today at ruins such as Harappa Buhen and Mohenjo-daro. Paintings on the tomb walls of Thebes portray slaves mixing, tempering and carrying clay for the sun dried bricks. These bricks also consisted of a 4:2:1 ratio which enabled them to be laid more easily.
The Romans further distinguished those which had been dried by the sun and air and those bricks which were burnt in a kiln. Preferring to make their bricks in the spring, the Romans held on to their bricks for 2 years before they were used or sold. They only used clay which was whitish or red for their bricks.
Using mobile kilns, the Romans were successful in introducing kiln fired bricks to the whole of the Roman Empire. The bricks were then stamped with the mark of the legion who supervised the brick production. These bricks differed from other ancient bricks in size and shape. Roman bricks were more commonly round, square, oblong, triangular or rectangular. The kiln fired bricks were generally 1 or 2 Roman foot by 1 Roman foot, but with some larger bricks at up to 3 Roman feet. The Romans preferred this type of brick making during the first century of their civilisation and used the bricks for public and private buildings all over the empire.
The Greeks also considered perpendicular brick walls more durable than stone walls and used them for public edifices. They also realised how the modern brick was less susceptible to erosion than the old marble walls.
During the 12th century bricks were reintroduced to northern Germany from northern Italy. This created the brick gothic period which was a reduced style of Gothic architecture previously very common in northern Europe. The buildings around this time were mainly built from fired red clay bricks. Brick Gothic style buildings can be found in the Baltic countries Sweden, Denmark, Poland, Germany, Finland, Lithuania, Latvia, Estonia, Belarus and Russia. The brick gothic period can be categorized by the lack of figural architectural sculptures which had previously been carved in stone. The Gothic figures were impossible to create out of bulky bricks at that time, but could be identified by the use of split courses of bricks in varying colours, red bricks, glazed bricks and white lime plaster. Eventually special shaped bricks were introduced which would imitate the architectural sculptures.
During the renaissance and Baroque periods, exposed brick walls became unpopular and brickwork was generally covered by plaster. Only during the mid 18th century did visible brick walls again regain some popularity.



Bricks now
Bricks are more commonly used in the construction of buildings than any other material except wood. Brick and terracotta architecture is dominant within its field and a great industry has developed and invested in the manufacture of many different types of bricks of all shapes and colours. With modern machinery, earth moving equipment, powerful electric motors and modern tunnel kilns, making bricks has become much more productive and efficient. Bricks can be made from variety of materials the most common being clay but also calcium silicate and concrete. With clay bricks being the more popular, they are now manufactured using three processes soft mud, dry press and extruded. Also during 2007 the new ‘fly ash’ brick was created using the by-products from coal power plants.
Good quality bricks have a major advantage over stone as they are reliable, weather resistant and can tolerate acids, pollution and fire. Bricks can be made to any specification in colour, size and shape which makes bricks easier to build with than stone. Brickwork is also much cheaper than cut stone work. However there are some bricks which are more porous and therefore more susceptible to dampness when exposed to water. For best results in any construction work, the correct brick must be chosen in accordance with the job specifications.



Brick Composition
Building bricks are a mixture of clay and sand which is mixed with water to create the correct consistency. Sometimes the bricks also have added lime, ash or organic matter which speeds up the burning of the brick. The clay mixture is then formed in moulds to the desired specification ready to be dried then burnt in the kiln. Clay: The properties and quality of bricks depend on the type of clay used. The most common form of clay used for everyday bricks, is that with a sandy consistency, silicate or alumina, which usually contains small quantities of lime or iron oxide. If the clay consists almost entirely of alumina it will be very plastic, but will shrink and crack in drying, wrap and become very hard under the influence of heat. Silica, when added to pure clay in the form of sand, prevents cracking, shrinking and warping. If there is a large proportion of sand used in the mixture the brick will be more textured and shapely. An excess of sand, however, renders the bricks too brittle and destroys cohesion. 25% of silica is said to be advantageous. Iron oxide in the clay enables the silica and alumina to fuse and adds considerably to the hardness and strength of the bricks. Iron oxidfe in the clay renders the silica and alumina fusible and adds greatly to the hardness and strength of the bricks. The iron content of the brick is evident in the colour of the brick and can be used to add the colour red into the bricks. However a clay which burns to a red colour will provide a stronger brick than clay which burns to a white or yellow brick. The lime content in a brick has two different effects. It stops the raw brick from shrinking and drying out, and it also acts as a flux during burning which causes the silica to melt and creates the bond which binds all the components of the brick together. However, too much lime can cause the brick to melt and loose shape. Any amount of quicklime within a brick is detrimental to its quality and can cause the brick to split into pieces. Dilute sulphuric acid can help to detect the presence of lime, if lime is present an effervescence will occur. For the best qualities of pressed brick the clay is carefully selected both colour and composition. Clay from different sources is also often mixed together to create the desired mixture.

The Clay Difference
Characteristics	Genuine Burned Clay Brick	Vinyl Aluminum or Wood Siding	What Clay Means to you
Colour	Enormous range of natural colours	Limited colour range	Improved resale value, lasting beauty
Colour Retention	Never fades - colour fired in at 1900°F Improves with age	Depending on material, colours fade. Wood needs painting	Clay brick is virtually maintenance free and gives higher resale valueance
Texture	Very wide range of bark, wire cut. Smooth, antique textures in all colours	Limited range	Clay brick allows greater variety of design and beauty resulting in higher resale value
Strength	8000 to 10, 000 psi (pounds per sq inch)	Not load bearing	Clay brick lasts for decades
"M" Factor	Up to 8 hours for clay brick to transfer 30°F difference from outside to inside wall	About 1 hour to transfer 30°F difference	Clay brick homes stay cooler in the summer and warmer in the winter
Moisture Absorbtion	Approx. 20 gms /minute per 30sq. ins	N/A	With Clay brick your home does not go through drastic colour change in rain
Repair and Maintenance	Little or no maintenance required with proper design detailing and good masonry practice	Replacement may be needed due to scratches, dents, and warpage. Wood requires painting	Clay brick looks better as it ages and requires virtually no maintenance

*Comparison information provided by the Clay Brick Association of Canada

Manufacturing Processes (Video:How Do They Do It: Brick Manufacturing)

Handmade bricks used to be very commonly used, especially in the smaller towns and cities, are still made in hand. The process involves putting the clay, water and additives into a large pit where it is all mixed together by a tempering wheel generally still powered by horse power. Once the mixture is of the correct consistency, the clay is removed and pressed into moulds by hand. To prevent the brick from sticking to the mould, the brick is coated in either sand or water. Named ‘slop moulding’ when dipped in water and ‘sand struck’ when coated in sand. Coating the brick with sand however gives an overall better finish to the brick. Once shaped, the bricks are laid outside to dry by air and sun where they will be drying for three to four days. After this process the bricks are then transferred to the kiln for burning. If green bricks are left outside for the drying process and are left out during a shower; the water leaves an indentation of the brick is considered very undesirable. However this does not affect the strength properties of the bricks.
Bricks are now more generally made by large scale manufacturing processes using machinery. This is a large scale effort and produces bricks which have been burned in patent kilns. There are three different types of manufacturing process for machine made bricks - the soft mud process, the stiff mud process and the dry clay process for which machines are specifically designed.
The 'Soft mud' process is similar to that of handmade bricks. In the Soft Mud process that clay contains too much water to be extruded as the clay is left to soak in water for 24 hours. For this process three pits are usually in operation at any one time to keep the production flowing. Occasionally the clay is worked in a pug mill before being thrown into the machine. Due to the 20% water content of the clay, wooden moulds are generally used and are lined with either oil or sand to stop the clay sticking. After being drawn from the machine the filled moulds are emptied by hand and the bricks taken to the dry shed. So the soft mud bricks can be dried properly, both handmade soft mud bricks and machine made (more mass produced) bricks will both be placed in a large dryer which is separate from the extrusion dryer.
The 'Stiff mud' process differs because only enough water to create plasticity is added to the clay, approximately 12% water. Clay is then extruded through a ‘die’ to produce a long stream of pressed clay which is then cut to size by the machine. The die sizes and cutter wire are calculated to compensate for the shrinkage of the brick during drying and firing. Attachments can also be added to the die which gives the brick its texture from brush, roll, and scratch to roughen. Green bricks are then dried out carefully to ensure a consistent colour and strength. Stiff mud bricks, owing to the nature of the clay and the details of manufacture, often contain laminations, or planes of separation, which more or less weaken the bricks. Those made by the plunger machine also sometimes contain voids caused by the air which occasionally passes with the loose clay into the pressure chamber, and, being unable to escape, passes out with the clay stream and renders it more or less imperfect. However Stiff mud bricks can have defects or planes of separation which can affect the bricks durability. Stiff Mud bricks are becoming increasingly cheaper to produce these are becoming the more popular. Because Soft Mud bricks have been created under little or no pressure, their density is not as great as that of Stiff Mud bricks. It has been argued in the soft mud bricks the particles adhere more closely when Soft Mud bricks have been made and burned properly they are possibly the most durable brick. The soft mud bricks take longer to dry, but are more easily burnt. Soft mud bricks, after having lain in a foundation on the shore of a river for fifty-four years, were found in as perfect condition as when laid. Soft mud bricks are also generally more perfect in shape than stiff mud bricks and better adapted for painting.
The ‘Repressing’ of a brick is to re-shape the brick or round of any corners dependent on specification. Both types of soft mud and stiff mud bricks can be repressed when they are only partially dried. This is done by placing the bricks in metal moulds and putting them under great pressure before burning. Pressed bricks however are machine moulded bricks where the clay being used is already nearly dry. This process can make a significant difference on the appearance of the bricks. Bricks made using this process generally are more difficult to compress. Dry pressed bricks however are now commonly used for face bricks. Pressed bricks generally mean dry pressed bricks, but many face bricks are made by repressing soft mud bricks. A properly formed stiff mud brick, however, is not improved in structure by repressing.
‘Cement’ bricks made from Portland cement, these bricks are machine moulded into size and shape to match the size of clay bricks. These are extensively used in some regions.
‘Hollow, Terracotta or Tile’. This type of product can made into practically and size or shape for any kind of use. Blocks made of terra-cotta are light and durable. For use in partitions the terra-cotta is mixed with sawdust which burns off in the kiln, but creates a more porous brick. Terra-cotta can be glazed or unglazed.


Types of Facing Bricks
Facing bricks are uniform in colour and shape and can now be made to any almost any specification, texture, colour and size.
Wirecut extruded bricks is extruded and cut by wore into individual bricks. This is a very cost effective way of producing bricks and is done by an automated production process. These bricks are readily available in a variety of styles and colours.

    

Stock bricks are usually slightly more expensive than wirecut bricks. These are a soft mud brick which are sometimes irregular in shape. The clay is wetted to a so-called ''soft mud'' and then moulded to shape, before being allowed to dry prior to firing in the kiln. Much of the process is automated.
  



Handmade bricks are very desirable and individual in shape and colour. This brick is one of the most expensive sorts of brick, but well worth it on pretige jobs. Usually made on a bench, in mould, much as described above for a stock brick. Because the clay is not firmly compacted by machine, each brick normally has distinctive creasing known as 'smile'.
    



Fletton or London Brick is a brick made from clay extracted from the south east of England which contains traces of oil which is burnt off during the burning process in the kiln. This clay contains coal traces, which burn during firing, reducing the amount of fuel needed for the kiln, which not only save costs but also produces some interesting effects in the bricks themselves.
    


Concrete or Calcium Silicate is popular in areas where good brick-making clay is scarce. Some are, quite frankly, bloody awful, but others may be split-faced or have a pitched face to give an impression of being something other than boring concrete. Cheap and cheerful sums them up.



Arch and Clinker bricks is used for bricks which are burned immediately. They are over burnt and sometimes distorted in shape. Body, Cherry and/or hard bricks. These bricks are of a higher quality and are generally the bricks that were in the centre of the pile of bricks which have been burned. These bricks are top bricks as they have a higher overall quality and finish. Cherry is used as a term when the clay which has been used burns red.
    



Salmon, Pale or Soft bricks are the bricks which were nearer to the outside of the kiln during burning which means they are slightly under burnt. These bricks are generally softer than the bricks taken from the centre of the kiln are therefore are of a lesser quality, although this does not affect the overall shape of the brick. These bricks are generally used for the interior of walls.
  


Waterstruck Brick is a soft mud moulded brick. It uses alluvial clay which deposited at the end of the last ice age. The clay is pressed into mould lined with silicate. When the bricks are removed from their mould, they are left with a textured effect which can only be achieved using this method. This type of brick looks old and handmade even when new.
    



Engineering Bricks are the workhorses of the bricks family. They are called so due to their overall strength and water absorption, but not usually very pretty. The Class A brick has strength of 125N/mm² and water absorption of less than 4.5%. Class B engineering bricks have a strength greater than 75N/mm² and water absorption of less than 7%. Traditionally used in civil engineering, these bricks are also useful for damp courses and structural design, making them ideal for groundworks, sewer works and retaining wall.
    



Off Shades or Seconds or ATR or Random Quality are batches of bricks which are generally consistent in colour but do not match the product which is marketed.



Special are any bricks that isn't a rectangle. Just to confuse non-bricklayers, there are ''standard specials'', such as bullnoses, cants and radials, and ''special specials'' such as cills and quoins. These specials allow fantastic design possibilities and make brickwork the most aesthetically pleasing medium for building.
 



Bullnose Bricks are used when round edges are needed, for gate recesses, quadrants or arches.
   

Different uses for bricks
Dependant on their final use, the bricks are named accordingly.
Radial Bricks either have one edge shorter than the other or vary in thickness. This type of brick is used for walls with curved edges. Arch bricks are used for arches as they have one end thicker than the other.
Ordinary bricks or facebricks and have regular shape and colour used for the outside of building etc.
Fire bricks are generally yellow in colour and used in places where they would be subject to high temperatures. Paving bricks are of uniform size and colour and have been made by burning hard clay or shale. Good brick to be used where toughness and water tightness is essential. Aesthetic appearance
Bricks can be made to virtually any specification,Overall strength and water absorption of clay bricks Compressive strengths vary from 5 N/mm2 to 125N/mm2
Water absorption varies from 6-26% dependant on brick type
Brick Dimensions Metric and imperial


Brick Sizes
Metric bricks are a little smaller than the old imperial one. New bricks can be bonded into old brickwork by slightly increasing the mortar bed joint. Brick sizes have remained fairly constant over the years :-
Metric and Imperial 215 × 102.5 × 50
Standard Metric215 × 102.5 × 65
Metric 225 × 107.5 × 67
Imperial 230 × 110 × 70
Imperial 230 × 110 × 73
Imperial 230 × 110 × 76
Imperial 230 × 110 × 80
Although in the UK, the depth used to be less (about 2 ins/51mm) whereas modern bricks are about 2.5 ins/64mm.

Brick Cutting
Brick cutting is the process of cutting bricks into the desired size or in most cases to cut and bond them together using an epoxy mortar to form angle bricks these are mainly used on bay windows and conservatories etc. Some bricks just wont cut with a hammer and bolster no matter how hard you try, they just shatter into pieces. Its usually wire cut bricks that do this, no all do it, just some brands and types.  Some bricks just won't cut and some brick are very hard to cut with a hammer and bolster due to their density, i.e dry pressed solids.
Thermal Efficiency and Compliance with Building Regulations http://www.bbacerts.co.uk/

Cut with a hammer and bolster

Measure the gap where the cut is to go, minus 20mm for two 10mm perpends at each end.This will be your cut size, in this case it will be a 145mm cut. 

Mark the bricks (this is a different cut and not a 145mm as show in the pic above.)

Keep all your cuts square otherwise the will really stand out when laid. If using a bolster to cut the brick and the cut is "near" a hole in the brick, angle the bolster towards the hole, the brick will cut much better.

Cut with brick splitter

When doing repetitive cuts a brick splitter is the way to go, once set up it will cut the same sized bricks all day. 

Cut with brick saw

Diamond blades glaze up when cutting hard vitrified bricks, you will see this as blobs of molten brick being shot out of the cut. You can revive the blade by running it through some waste concrete or mortar for a few seconds, this will de-glaze the blade.

Kiln Brick Burning
After all bricks have been allowed time to dry they are placed in a kiln for burning which finishes off the brick to achieve the optimum strength and colour.
There a few different types of kilns which are currently used to burn bricks.
The Scotch Kiln is the most commonly used in the UK. This is a rectangular building which is open at the top and has side doors with fireholes built from fire bricks. The kilns will contain approximately 80, 000 bricks at full capacity. Raw bricks are arranged in the kiln leaving gaps in between each brick to ensure an even burn. It takes approximately three days to burn off the moisture from the bricks, at which point the firing is increased for the final burn. It takes between 48 and 60 hours to completely burn a brick to achieve its maximum strength. As mentioned before the bricks from the centre of kiln will be of the highest quality whilst the ones from the edges are sometimes clinkered and unsuitable for exterior work.
Up Draft Kiln is more frequently used for handmade bricks and in small brick yards, this old fashioned kiln is only up to 15 feet high.
Down Draft Kilns are generally of a beehive type shape with fire produced outside of the kiln and carried in through flues. It is believed that all types of clay whether it be pottery or brick work, burn more evenly in a down draft kiln. For Terra-cotta brickwork this type of kiln is usually used.
Continuous kilns are the most expensive type of kiln to construct. This type of kiln is a continuously fired tunnel in which the bricks pass through very slowly on a rail to achieve a consistently durable brick. This is continuous conveyor belt with bricks being dried and added at one end while at the other end they are being burnt. This is a very efficient way of burning bricks. They also achieve a greater number of grade 1 bricks using this method.


Mortars
To make any kind of brick work complete it must be plied together with mortar. The way in which the bricks are bonded together is vital to the strength of the overall structure. Concrete mortars contain aggregates of more than 5mm where as mortar contains aggregates less than 5mm.
General purpose mortar contains either
Sand, lime and cement
Sand and masonry cement
Sand, cement and plasticiser
Mortar is then graded between 1 and 5 depending on strength. 5 being the weakest.
Mortar Cement-Lime-Sand Cement- Sand Cement – Sand-plasticiser
The mixture has to be mixed together with clean water before it is ready to use
Normal bricks should be laid on a bed of mortar at least 3/16" and no more than 3/8" thick. For a course of bricks 8 courses high, your mortar should not exceed 2" in total. With pressed bricks being smoother a mortar joint of 1/8" can be used. For rough stone work a mortar with rough sand can be used, but for pressed brickwork it must be very fine sand.
Lime Mortar
Slaked lime is used to make lime mortar. The mortar is made by mixing sand with slaked lime at the proportion of 1 part lime to 5 parts sand. There are two types of lime used in lime mortars, one that sets and hardens by the reaction with the air (non-hydraulic) and one which sets by reaction to the water (hydraulic).

Non-hydraulic lime is made from pure calcium carbonate, or chalk or limestone. This is burned in a kiln to create calcium oxide or quicklime. When this is slaked with water it takes on another form as calcium hydroxide. Calcium hydroxide reacts with the air to set. This is what sets the brickwork together and creates the strength.

Hydraulic Limes. Calcium carbonates naturally occur but can include some impurities. It is these impurities which when burned in a kiln create the calcium silicates or aluminates that react with water to set. Enough water is added to the mixture to create calcium hydroxide powder form. The hydraulic lime is then graded depending on their overall set strength.

White and Coloured Mortar

White and coloured mortars should be made using lime putty and screened sand. Colour is created by adding additional minerals to the white mortar. Coloured mortars are not as strong as white mortars. However the more popular mortar colours are red, brown, buff and black, green, purple and grey.

Cement Mortars
Cement mortars should be used in areas of damp or below grade work, also in places which will have heavy loads such as arches. Cement mortars should also be used for setting coping stones or where the brick work will be exposed to the elements. For under water construction Portland cement mortars should be used.
Mortar Tinting from Bricks UK available at http://www.extensionmatch.co.uk/motartinting.html
When new extensions or refurbished brick and stonework are being carried out, matching the mortar joint with the original brick work can be a problem. Extension Match colour tinting extends to mortar tinting. We can match mortar colours perfectly and permanently and all work is guaranteed for the life of the brickwork.
Grout can also be tinted. Shown below is a tiled bathroom floor - the customer was not happy with the original grout finish so we tinted the grout joint which transformed the overall appearance of the tiled floor.
For example: Brick Tinting from Bricks UK available at http://www.extensionmatch.co.uk/motartinting.html Brick tinting has been used for decades by brick and masonry manufacturers and also by many developers on new house sites when there are problems between different batches of manufactured bricks, delivered on site which causes slight shade and colour differences between one lorry load of bricks and another. Tinting is then used to match the affected bricks to the colour of the original bricks, seamlessly blending the different batches together. Brick tinters do not "paint" the brick with pre-set coloured paints, the process is a chemical and oxide solution involving various colour dyes. Each match is unique and the dye is mixed on site by our specialists once they have assessed the required colours to match, including and varying blends.Matching and creating the colour on site ensures that we get the exact colour dye solution to match your individual brick in your individual situation.

The solutions change the produced colour of the brick, it is not a paint simply applied to the face of the brick, it will naturally whether just as the normal brick would, mature over the years. All work is fully guaranteed for the life of the brick.

Brickwork Bonds 

Brickwork bonding is how the bricks are arranged. They usually overlap in between courses which helps distribute the load and provide a more stable structure. General brickwork should not be less than ¼ bonded with mortar.

English Bond

An English bond has alternating courses of headers and stretchers. The alternative headers 

should be centred over and under the vertical joints.

English Cross Bond

A pattern similar to English Bond, in which rows of stretchers alternate with rows of headers. It is different in that the stretchers are centred on the joins between the stretchers immediately below them, so that alternating rows of stretchers are aligned.

Flemish Bond

This bond has alternating headers and stretchers along each course. The headers should be 

centred above the stretchers above and below.

Monk Bond

A variant of Flemish Bond, with two stretchers between the headers in each row, and the headers centred over the join between the two stretchers in the row below.

Flemish Garden Wall Bond

A variant of Flemish Bond, with three stretchers between each header, and the header centred over the stretcher in the middle of a group of three in the row below. 

Stretcher bond

This bond is the most commonly used today. Bricks used to make this bond are just half a 

brick wide. As with any brickwork, no two adjacent vertical joints should be in line. When 

turning a corner at the end of straight run, the two runs should be interlocked on every other 

course.

 

American Common Bond

This bond is very similar to the English Bond but its headers run one in every six courses of

stretchers.

Header Bond

This type of bond is used for walls which need to be curved. It is made by full bricks laid 

header wise with a ¾ bat on alternate courses.

Stack Bond

A pattern made up of rows of stretchers with each stretcher centred on the stretcher below it. All joins run vertically down the entire wall. Not a strong bond at all, it is used only for decorative purposes.  Mathematically this pattern displays the symmetry pmm.

PointingPointing is effectively the application and maintenance of the mortar which bonds the brickwork. After the masonry has been laid, the gaps are in filled with mortar, this is known as pointing. Pointing should not be done during any extreme hot or cold weather.
If re-pointing, any vegetation growing on the mortar should be removed and the existing mortar should be chiselled back. This should be done using either s plugging chisel, club hammer or mini angle grinder to a depth of 13mm.
All the debris should then be washed off and the walls should be left to dry before the re-pointing begins. The mortar used for the pointing should be 1 : 3 parts and be quite stiff so the mixture does not fall of the trowel.

Different types of Pointing

Weather Struck Joint are formed with trowels. The inset edge of the joint should not be exaggerated, about 2mm is enough – the thickness of a trowel blade is a guide. The forward edge should finish on the edge of the brick. Cross joints are formed first. A small pointing trowel is held with its edge pressed into the mortar against one brick and drawn across the joint against the other. A right-handed bricklayer tends to form the inset on the left side and draw to the right. Either direction is acceptable, but make sure that it is the same throughout the work; otherwise the brickwork will look patchy. Bed joints are formed with the straight edge of a normal trowel pressed into the mortar against the upper brick and, while holding it against the edge of the lower brick, pushing it along and down. The straight sloping surfaces of the bed joints tend to catch the light and accentuate them. This joint can give the work a neat, well-ordered appearance and looks best with well-formed regular bricks.

Weather Struck and Cut Pointing are formed as pointing. The inset edge is produced as it is with ‘weather struck’, but the forward edge is projected about 2mm beyond the brick surface. It is similar to struck joint but the bed joints are neatly trimmed using a Frenchman or pointing trowel. For the cross joints the projection is cut vertical and straight using the edge of a pointing trowel. For the bed joints the projection is cut using a straightedge and a ‘Frenchman’, a knife with a specially shaped blade. The straightedge has blocks to hold it off the wall surface to avoid smearing and so that the mortar cut off can fall down and away. This profile also accentuates the bed joints and looks well with well-formed regular bricks. If used with irregular bricks, inevitable variations in the width of the joints tend to produce a heavy, somewhat coarse appearance.

Tooled, Bucket Handel Joint is the most popular joint used today, where the joint bed is slightly rounded inwards. The mortar should not be pressed in too hard. The tool needed for this job is a rubber hose, an old type bucket handle. It is formed with a jointer that is half round or circular in section. The tool is pulled along the joint in contact with the edges of the bricks on either side. Cross joints are finished first, then the bed joints. The diameter of the tool determines the depth of the curved recess – a small diameter of 12mm produces a strongly curved deep profile while one of 25mm produces a shallow curve only about 2mm deep. Purpose-made metal jointing tools are available, but off-cuts of metal or rubber tubing are frequently used. Metal and plastic tend to polish the surface of joints and this can produce a harsh character. Off-cuts of hard rubber hose (such as those used in car engines) compact the mortar surface, but roughen it slightly to leave an attractive sandy texture. Timber dowelling produces a similar texture, but is best avoided as it wears quickly and so leads to inconsistency. Whatever tool is chosen, its use should be consistent throughout the work.

For a Flush Joint profile no further working need be done. Because flush joints are formed without compacting the surface of the mortar they are less resistant to water penetration than profiles formed by tooling. For other joint profiles the mortar is left to stiffen slightly and then tooled. The time taken for the mortar to reach the correct consistency varies considerably and checking should start after approximately 10 minutes. It must be stiff enough not to flow or adhere to tools, but not so stiff that it crumbles and breaks away when tools are applied. This finish of this joint is flush with the brick work, smoothed off with a rag. This finish should only be used for brickwork above water level.

Recessed Joints are raked out to a consistent depth. A wheeled jointer is an effective tool for this. The raked profile can be left as roughened texture, but it is better to compact the surface of the mortar to improve its resistance to rain penetration. A square-edged jointer or a slipper iron in a wheeled jointing tool can be used. A recess of about 5mm produces a good visual effect; exaggerated recessing of 10mm or more should be avoided. Recessed joints impede the flow of rainwater down the surface of the brickwork, which tends to get wetter than it does with other profiles. For this reason recessed joints are not recommended unless the bricks are eminently frost-resistant, that is, conforming to durability designation F2 in BS EN 771-1 Specification for Clay Masonry Units. They are not recommended in locations liable to severe exposure to wind-driven rain for brickwork in which resistance to water penetration is important. This Finish of this joint is recessed. The mortar is formed to a consistence depth of approximately 5 mm. This joint should only be used with a frost resistant brick and is not recommended where the brickwork could be exposed to severe wind driven rain. This Finish of this joint is recessed. The mortar is formed to a consistence depth of approximately 5 mm. This joint should only be used with a frost resistant brick and is not recommended where the brickwork could be exposed to severe wind driven rain.

This type of joint should be used when the bricks have become uneven over time due to weathering. The joint is pointed by filling the perp joint first and then the bed joint which would be shaped by placing the trowel on the perp joint and angling it downwards to create a smooth finish.

Finishes

Walls were never painted. However, roughcast and pebbledash finishes were common, particularly to cover cheaper bricks, and later for more decorative purposes. Roughcast is a mixture of shingle or crushed stone and sand mixed with a cement. To achieve a pebbledash finish, the wall is first coated with cement, and then pea shingle or some other fine stone chippings are thrown onto the soft cement. Another treatment common, after the 1870s in Gothic and Arts and Crafts styles, is tile or slate-hanging.

tile-hung wall