Bricks are one of the oldest types of building blocks. They are an ideal building material because they are relatively cheap to make, very durable, and require little maintenance. Bricks are usually made of kiln-baked mixtures of clay. In ancient times, bricks were made of mud and dried in the sun; modern bricks are made from concrete, sand and lime, and glass. The physical and chemical characteristics of the raw materials used to make bricks, along with the temperature at which they are baked, determine the color and hardness of the finished product. Bricks are made in standard sizes, are usually twice as long as they are wide and, since most bricklaying is done manually, are made small enough to fit in the hand. Bricklayers use a trowel to cover each brick with mortar—a mixture of cement, sand, and water. The mortar hardens when dry and keeps the bricks in place. Bricks are arranged in various patterns, called bonds, for strength.
Bricks are laid to expose their ends (Header bricks), or sides (Stretcher bricks). As the work progresses, the bricks are laid in rows called courses. The manner in which the bricks overlap as they are laid up is called the bond of which there are two main types: half bond and quarter bond. Types of bonding arrangements include English bond, Flemish bond, and Herringbone bond, but the most common type of brickwork seen these days is the simple stretcher bond, showing only the long side-surface of the brick.
Because only the outside of finished brickwork is visible, cheaper grades of brick are commonly used for the hidden parts of a wall. In an old red-brick house, behind the front of red, the rest of the walls are often made of softer yellow bricks. The colour situation may be reversed if the house was built when red bricks were out of fashion. So with certain types of bond (e.g. garden wall bond) it is possible to use a higher ratio of cheaper bricks to more expensive bricks, making for a cheaper wall of the same dimensions. On the same house, sometimes a more economical "garden wall" bond has been used at the side and rear compared to the front.
The thickness of brickwork is casually quantified in units of brick referring to the length of a brick. A double-skinned wall will have some bricks laid across both skins or courses and therefore the wall will be as thick as the length of the brick. Because most typical bricks are roughly twice as long as the are wide, a single-skinned (or single course) wall with bricks laid end to end will be as thick as the brick as wide, which is roughly half the length of a the brick it is called "half brick" thick. Simply put, single-skinned walls are expediently or casually referred to as "half brick" thick and double-skinned walls "full brick" thick even though technically this is only an approximation relevant to bricks roughly half as wide as they are long.
If bricks are put down end-to-end with the long side facing you (stretchers) and then another row on top, the wall thickness is half a brick.
There are rules of bonding, which have some exceptions. These specify the overlap between courses that is visible outside the wall, and also the overlap which must be made within the wall, for walls which are more than half a brick thick.
Brickwork, like unreinforced concrete, has little tensile strength, and works by everything being kept in compression.
Grading of Bricks
- GRADE SW is brick designed to withstand exposure to below-freezing temperatures in a moist climate like that of the northern regions of the United States.
- GRADE MW is brick designed to withstand exposure to below-freezing temperatures in a drier climate
- GRADE NW is brick primarily intended for interior or backup brick. It may be used exposed; however, it can only be used in regions where no frost action occurs.
Types Of Bricks
- Brick masonry units may be solid, hollow, or architectural terra cotta. All types can serve a structural function, a decorative function, or a combination of both. The various types differ in their formation and composition.
- Building brick, also called common, hard, or kiln-run brick, is made from ordinary clay or shale and is fired in kilns. These bricks have no special shoring, markings, surface texture, or color. Because building bricks are generally used as the backing courses in either solid or cavity brick walls, the harder and more durable types are preferred.
- Face brick is better quality and has better durability and appearance than building brick. Because of this, face bricks are used in exposed wall faces. The most common face brick colors are various shades of brown, red, gray, yellow, and white.
- Clinker brick is overburned in the kiln. Clinker bricks are usually rough, hard, durable, and sometimes irregular in shape.
- Pressed brick is made by a dry-press process, rather than by kiln firing. Pressed bricks have regular, smooth faces, sharp edges, and perfectly square corners. Ordinarily, they are used like face brick.
- Glazed brick has one surface coated with a white or colored ceramic glazing. The glazing forms when mineral ingredients fuse together in a glasslike coating during burning. Glazed bricks are particularly suited to walls or partitions in hospitals, dairies, laboratories, and other structures requiring sanitary conditions and ease of cleaning.
- Fire brick is made from a special type of clay. This clay is very pure and uniform and is able to withstand the high temperatures of fireplaces, boilers, and similar constructions. Fire bricks are generally larger than other structural bricks and are often hand-molded.
- Cored bricks have ten holes—two rows of five holes each-extending through their beds to reduce weight. Walls built from cored brick are not much different in strength than walls built from solid brick. Also, both have about the same resistance to moisture penetration. Whether cored or solid, use the more available brick that meets building requirements.
- European brick has strength and durability about equal to U.S. clay brick. This is particularly true of the English and Dutch types.Sand-lime brick is made from a lean mixture of slaked lime and fine sand.
- Sand-lime bricks are molded under mechanical pressure and are hardened under steam pressure. These bricks are used extensively in Germany.
Strength Of Brick Masonry
The main factors governing the strength of a brick structure include brick strength, mortar strength and elasticity, bricklayer workmanship, brick uniformity, and the method used to lay brick. In this section, we’ll cover strength and elasticity. “Workmanship” is covered separately in the next section. The strength of a single brick masonry unit varies widely, depending on its ingredients and manufacturing method. Brick can have an ultimate compressive strength as low as 1,600 psi. On the other hand, some well-burned brick has compressive strength exceeding 15,000 psi. Because portland-cement-lime mortar is normally stronger than the brick, brick masonry laid with this mortar is stronger than an individual brick unit. The load-carrying capacity of a wall or column made with plain lime mortar is less than half of that made with portland-cement-lime mortar. The compressive working strength of a brick wall or column laid with plain lime mortar normally ranges from 500 to 600 psi.
Masonry is commonly used for the walls of buildings, retaining walls and monuments. Brick is the most common type of masonry and may be either weight-bearing or a veneer. Concrete block masonry is rapidly gaining in popularity as a comparable material. Blocks - most of which have hollow cores - offer various possibilities in masonry construction. They generally provide great compressive strength, and are best suited to structures with light transverse loading when the cores remain unfilled. Filling some or all of the cores with concrete or concrete with steel reinforcement (typically "rebar") offers much greater tensile and lateral strength to structures.
Advantages
- The use of materials such as brick and stone can increase the thermal mass of a building, giving increased comfort in the heat of summer and the cold of winter and can be ideal for passive solar applications.
- Brick typically will not require painting and so can provide a structure with reduced life-cycle costs, although sealing appropriately will reduce potential spalling due to frost damage. Non-decorative concrete block generally is painted or stuccoed if exposed.
- The appearance, especially when well crafted, can impart an impression of solidity and permanence.
- Is very heat resistant and thus will provide good fire protection.
- Masonry buildings offer a better shelter against extreme weather phenomena like harricane or debris coming from a windmill or a tornado than the shelter offered by wooden buildings.
Disadvantages
- Extreme weather may cause degradation of the surface due to frost damage. This type of damage is common with certain types of brick, though relatively rare with concrete block. If non-concrete (clay-based) brick is to be used, care should be taken to select bricks suitable for the climate in question.
- Masonry must be built upon a firm foundation (usually reinforced concrete) to avoid potential settling and cracking. If expansive soils (such as adope clay ) are present, this foundation may need to be quite elaborate and the services of a qualified structural engineer may be required.
- The high weight increases structural requirements, especially in earthquake prone areas.
Brickwork
Brickwork masonry is produced when a bricklayer uses bricks and mortar to build up structures such as walls, bridges and chimneys. Brickwork is also used to finish openings such as doors or windows in buildings made of other materials. Where the bricks are to remain fully visible, as opposed to being covered up by plaster or stucco, this is known as face-work.
Bricks are laid to expose their ends (Header bricks), or sides (Stretcher bricks). As the work progresses, the bricks are laid in rows called courses. The manner in which the bricks overlap as they are laid up is called the bond of which there are two main types: half bond and quarter bond. Types of bonding arrangements include English bond, Flemish bond, and Herringbone bond, but the most common type of brickwork seen these days is the simple stretcher bond, showing only the long side-surface of the brick.
Because only the outside of finished brickwork is visible, cheaper grades of brick are commonly used for the hidden parts of a wall. In an old red-brick house, behind the front of red, the rest of the walls are often made of softer yellow bricks. The colour situation may be reversed if the house was built when red bricks were out of fashion. So with certain types of bond (e.g. garden wall bond) it is possible to use a higher ratio of cheaper bricks to more expensive bricks, making for a cheaper wall of the same dimensions. On the same house, sometimes a more economical "garden wall" bond has been used at the side and rear compared to the front.
The thickness of brickwork is casually quantified in units of brick referring to the length of a brick. A double-skinned wall will have some bricks laid across both skins or courses and therefore the wall will be as thick as the length of the brick. Because most typical bricks are roughly twice as long as the are wide, a single-skinned (or single course) wall with bricks laid end to end will be as thick as the brick as wide, which is roughly half the length of a the brick it is called "half brick" thick. Simply put, single-skinned walls are expediently or casually referred to as "half brick" thick and double-skinned walls "full brick" thick even though technically this is only an approximation relevant to bricks roughly half as wide as they are long.
If bricks are put down end-to-end with the long side facing you (stretchers) and then another row on top, the wall thickness is half a brick.
There are rules of bonding, which have some exceptions. These specify the overlap between courses that is visible outside the wall, and also the overlap which must be made within the wall, for walls which are more than half a brick thick.
Brickwork, like unreinforced concrete, has little tensile strength, and works by everything being kept in compression.
Brickwork arches can span great distances, and carry considerable loads.
Types of bond
When laying bricks, the manner in which the bricks overlap is called the bond. A brick laid with the longest side exposed is called a stretcher brick, as opposed to a header, where only the smallest end of the brick is exposed to the weather. The length of one stretcher is the same as two header bricks, side-by-side, including the 10mm joint between.
The thickness of a brick wall is measured using a unit of length known as 'the brick'. This standard can be used consistently with the wide variety of brick sizes available ("modular, "Norman" brick, etc.). The length of the longest face for a particular size of brick equals "one brick", for the purposes of measuring a wall built from such bricks.
Stretcher bond (also known as running bond) is the most common bond in modern times, as it is easy to lay, with little waste. Entirely comprised of stretcher bricks, set in rows (or "courses") that are offset by half a brick.
Running bond uses no header bricks, allowing for a thin wall of one layer (half of a 'brick' unit). Two such walls may be built close together with a gap between. The two "skins" are usually tied together at regular intervals using wall ties. For this reason this bond is sometimes known as "cavity wall bond", although it is possible to give the appearance of other bonds in a half-brick cavity wall, either through extensive brick-cutting or the use of purpose-made half-bricks. In some climates the cavity may be filled with cavity wall insulation.
Stretcher bond may also be used to build a single-wythe (one brick thick) wall without a deliberate cavity. In this case, wall ties are used to hold the two wythes together. The main advantage of this technique is that it allows walls with both faces visible, such as domestic dwarf walls (low-height walls where the part of the structure above is built of a lighter, framed material such as glass) to be built using low-cost bricks that have only two fair faces, called "face bricks". Laying any such brick as a header would reveal a poorly finished header face on one side of the wall.
- English bond
This bond is made up of alternating courses of stretchers and headers. This produces a solid wall that is a full brick in depth. English bond is fairly easy to lay and is the strongest bond for a one-brick-thick wall. If only one face of an English bond wall is exposed, one quarter of the bricks are not visible, and hence may be of low visual quality.
Quarter bond is formed by a part (or bat) brick known as a 'queen closer'. This is a brick cut in half lengthways, generally along the frog and laid in the course next to the corner brick or 'quoin header'. Whereas the stretcher or half bond is formed by successive courses being staggered by half a brick, the Flemish and English bonds are now staggered by a quarter, resulting in a stronger bond (the constructional self-weight being distributed over a greater area). This bond, as well as Flemish bond, does not necessarily have to be one brick thick, they can be built using 'snap headers' ie. headers cut to half their length, which give a full brick appearance. They are often used in cavity walls when matching existing solid wall patterns.
Header bond (also known as Spanish bond) was a very common bond for bearing walls. It is composed of header bricks, set in rows that are offset half a brick, which produces a solid easy to lay bond which is useful when building circular work. It is the most used bond in historical Spanish brick constructions.
Flemish bond, also known as Dutch bond, has historically always been considered the most decorative bond, and for this reason was used extensively for dwellings until the adoption of the cavity wall. It is created by alternately laying headers and stretchers in a single course. The next course is laid so that a header lies in the middle of the stretcher in the course below. Again, this bond is one brick thick. It is quite difficult to lay Flemish bond properly, since for best effect all the perpendiculars (vertical mortar joints) need to be vertically aligned. If only one face of a Flemish bond wall is exposed, one third of the bricks are not visible, and hence may be of low visual quality. This is a better ratio than for English bond, Flemish bond's main rival for load-bearing walls.
A common variation often found in early 18th century buildings is Glazed-headed Flemish Bond, in which the exposed headers are burned until they vitrify with a black glassy surface. Monk bond is 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.
Scottish bond used in Cape May lighthouse
Rat-trap bond used in a garden wall. Note the increased height of each course, compared with flemish or english bond, achieved by laying the bricks on their edges
These bonds are variations on normal bonds. They use a high proportion of stretchers, and hence require fewer facing bricks than normal bonds. This makes them less sturdy, but cheaper to lay. As such they are most commonly used for garden- and other non-load-bearing walls.
Rat-trap bond is a type of garden wall bond in which the stretchers and headers are laid on their sides, with the base of the stretcher facing outwards. This gives a wall with an internal cavity bridged by the headers, hence the name. The main advantage of this bond is economy in use of bricks, giving a wall of one brick thickness with fewer bricks than a solid bond. Rat-trap bond was in common usage in England for building houses of fewer than 3 stories up to the turn of the 20th century and is today still used in India as an economical bond, as well for the insulation properties offered by the air cavity. Also, many brick walls surrounding kitchen gardens were designed with cavities so hot air could circulate in the winter, warming fruit trees or other produce spread against the walls, causing them to bloom earlier and forcing early fruit production.
When bricks are laid on alternating angles, it is called a Herringbone. This is primarily a decorative style, more often used for paving or fireplace reflectors than for walls. It is generally considered unsuitable for load-bearing structures, but may be found as infill in traditional timber framed buildings. This style is also sometimes called by its Latin name: Opus spicatum.
This decorative pattern imitates the weave of a basket. It's also sometimes called a basket weave bond, and there are many variations on the weave pattern, some very elaborate.
American common bond is made by laying the courses of headers where they are separated by approximately five to seven courses of stretchers. On occasion American common bond can be found with nine courses of stretchers between courses of headers. The stretcher courses are most often an uneven number. English common bond is an early variation with only three courses of stretchers between header courses.
As in flemish bond, but all the bricks are laid on edge. Unusual, but used to make a light weight structure or economise on bricks. Creates a semi-cavity wall.
Terminology
- Bat
A brick cut in half or quarter along the short face.
- Closer
A queen closer is brick cut in half down the long face. Used in corners of English
or Flemish bond.
- Header
Brick is laid in a wall, usually connecting two rows of a double wythe wall. The smallest end of the brick is horizontal, aligned with the surface of the wall and exposed to the weather.
- Quoin, "coin"
(or "coin" - are groups of brick that project slightly from the face of a wall at the corner of a building. The pattern often alternates with several courses projecting bricks, and several courses that are aligned with the wall. The pattern of projecting quions often alternates with the brickwork on the other side of the corner.
Rowlock or 'Brick on edge' (UK)
A complete course of brick laid on its side, with the shortest end of the brick exposed and vertical. Commomly used on the top course as a coping for garden walls.
- Sailor
Brick laid vertically on its end with the largest, broad face exposed.
- Shiner
Brick laid on edge like a sailor, but the broad face is set horizontally.
- Soldier
Often a complete course of brick laid on end vertically, with the narrow side exposed in the face of the wall.
A "standing soldier" is the most common way of setting the soldier brick on end that is flush with the wall. A "walking soldier" is a soldier course laid so the bottom edge of the brick is sticking out to about an inch. Usually alternating every other brick with a standing soldier, but other variations have been seen.
- Stretcher
Brick (or other masonry block) laid horizontally in the wall with the long, narrow side of the brick exposed. Commonly used for English bond and Flemish bond pattern, alternating with header bricks.
Advanced types/Uses Of Bricks
1. Fire Brick-A fire brick, firebrick, or refractory brick is a block of refractory ceramic material used in lining furnaces, kilns, fireboxes, and fireplaces.
A refractory brick is built primarily to withstand high heat, but should also usually have a low thermal conductivity to save energy. Usually dense firebricks are used in applications with extreme mechanical, chemical, or thermal stresses, such as the inside of a wood-fired kiln or a furnace, which is subject to abrasion from wood, fluxing from ash or slag, and high temperatures. In other, less harsh situations, such as a natural gas fired kiln, more porous bricks are a better choice. They are weaker, but they are much lighter, easier to form, and insulate far better than dense bricks. In any case, firebricks should not spall under rapid temperature change, and their strength should hold up well during rapid temperature changes.
To make firebrick, fireclay is baked in the kiln until it is partly vitrified, and for special purposes may also be glazed. Fire-bricks usually contain 30-40% aluminium oxide or alumina and 50% silicon dioxide or silica. They can also be made of chamotte and other materials. For bricks of extreme refractory character, the aluminium oxide content can be as high as 50-80% (with correspondingly less silica), and silicon carbide may also be present. The standard size of fire-brick is 9 x 4.5 x 2.5 in. (228 mm x 115 mm x 64 mm)
The silica firebricks that line steel-making furnaces are used at temperatures up to 1650 °C (3000 °F), which would melt many other types of ceramic, and in fact part of the silica firebrick liquifies. HRSI, a material with the same composition, is used to make the insulating tiles of the space shuttle.
A range of other materials find use as firebricks for lower temperature applications. Magnesium oxide is often used as a lining for furnaces.
History
The first application of silica "tiles" within ceramic brick kilns or furnaces is credited to William Harry of the Swansea Valley, Glamorganshire, Wales in 1817. Harry's invention served to vitrify the interior surface of ceramic brick built blast furnace. In 1820 however Quaker entrepreneur William Weston Young began experimenting with silica clay recipes, at his pottery in Nantgarw, also in Glamorganshire, for the creation of a robust, heat-proof brick from which a whole blast furnace could durably be made.
In 1822, Young, with three further investors, including David Morgan, John Player and (Young's brother) Joseph Young established The Dinas Firebrick Co. in the Vale of Neath, Glamorganshire, Wales and the first batches of firebricks began to be exported for the construction of blast furnaces across the industrialized world.
The Welsh word "Dinas," a reference to the hill where the silica was quarried in the upper Neath Valley, (Craig-y-Dinas, at Pontneddfechan) is synonymous with the word firebrick in many foreign languages, as a result of the extensive influence of this industry in South Wales.
Silica bricks were also manufactured in the upper Swansea Valley by the Penwyllt Dinas Silica Brick Co.
Manufacturing
A process for manufacturing heat-insulating firebricks wherein an alumina cement, a water-soluble styrene maleic resin and water are added to a mixture containing a refractory aggregate, an inorganic binder and a granular foamed polystyrene, the resultant mixture being then kneaded and cast in a mold. The added amounts of alumina cement and water-soluble styrene maleic resin are small and water is added to an extent of not more than 50% by weight. The alumina content in the alumina cement is between 8 and 75% by weight.
2.Alumina Light Weight Bricks
A production technique has been worked out for the manufacture of high-alumina lightweight brick by the combustible additive method with semi-dry pressing of the mixtures.
These parts can be used for the working layer of the lining at temperatures up to 1550°.
The long-term advantage of using high-alumina lightweight brick in the lining of fire-boxes for auxiliary boilers aboard ships using liquid fuel has been established. It is possible that this brick may be used in the future for lining the fire-boxes of the main boilers as well.
To satisfy the requirements of the navy we must organize the production of high-alumina lightweight brick at the refractory plants of the South and East.
3.Light-Weight Fiber Brick
A light-weight fiber brick is formed from a water-fiber suspension including ceramic fibers. A molding device is introduced into the suspension and has plurality walls including at least three walls each of which extends perpendicular to the other two of the three walls. Water is withdrawn simultaneously from the interior of the molding device through at least the three walls, thus causing the fibers of the suspension to tend to align longitudinally within the interior of the molding device in three spatial coordinate directions (X, Y, Z). Thereby there is formed a brick having fibers thereof aligned with longitudinal directions thereof having directional components in three spatial coordinate directions.
4.Acid/Chemical Resistant Bricks
These brick are currently in use in such industries as chemicals, steel, and metalworking, pharmaceuticals, pulp and paper, food and beverage, public utilities, aircraft, automotive and electronics. Typical applications in these industries are represented by process vessels, plating tanks, storage tanks, reaction vessels, fume ducts, scrubbers, bleach towers, waste treatment pits, rinse lines, and pickling tanks.
Chemical resistant masonry construction is designed to protect containment tanks and vessels made of steel, concrete, ordinary masonry, fiber-reinforced polyesters and the like. Chemical resistant brick provides thermal, mechanical, and chemical protection for these kinds of structures.
Chemical resistant brick is a particularly versatile construction material for sulfuric acid plants when installed as linings for carbon steel shells. These linings can be used regardless of the size of the vessels or equipment when prescribed construction techniques are followed. They can lower the temperature of the surface of the shell and eliminate erosion of the protective sulfate film. No other system of corrosion resistance can provide the same level of cost effective protection in wet areas where acid concentrations vary from 2% to 98% and at high temperatures, as the three component system using chemical resistant brick and mortar with a membrane backing
.
Chemical resistant bricks being used in inner lining of chambers
5.Glass bricks
also known as glass block, is an architectural element used in areas where privacy or visual obscuration is desired while admitting light, such as underground parking garages, washrooms, and municipal swimming baths. Glass block was originally developed in the early 1900s to provide natural light in industrial factories.
Glass brick can admit light without compromising security, since a typical size of glass brick is 8 by 8 inches, fitting within the lattice of standard 8 by 16 inch cinderblock walls.
Electrical circuits such as lights can be isolated by placing them in a very small room or passageway outside the area being illuminated, such that no electrical leakage is possible. This also helps prevent vandalism and theft of bulbs, or removal of bulbs (e.g. to perpetrate crime.)
Glass brick is often used to create visual privacy barriers, such as shown in the illustration above, where it has been used to create gender privacy through a doorless labyrinth that forms a washroom/changeroom entrance that allows light to pass, unrestricted, but distorts visual coherent light to such a degree as to provide reasonable privacy.
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