BRICK brick is a block of ceramic material

BRICK - brick is a block of ceramic material used in masonry construction and sized to be laid with one hand using mortar ranbsingh

Methods of manufacture Bricks may be made from clay, shale, soft slate, calcium silicate, concrete, or shaped from quarried stone. A new type of brick based on fly ash, has been invented recently Clay is the most common material Modern clay bricks formed in one of three processes -soft mud -dry press -extruded. ranbsingh

Mud bricks The soft mud method is the most common It starts with the raw clay preferably in a mix with 25 -30% sand to reduce shrinkage The clay is first ground and mixed with water to the desired consistency forming in a mould The clay is pressed into moulds The shaped clay is then fired ("burned") at 900 -1000 °C to achieve strength In modern brickworks, this is usually done in a continuously fired tunnel kiln (Rail Kilns), in which the bricks move slowly through the kiln on conveyors, rails, or kiln cars to achieve consistent physical characteristics for all bricks ranbsingh

Mud bricks (Contd. ) The bricks often have added lime, ash, and organic matter to speed the burning. In India, brick making is still typically a manual process. The most common type of brick kiln in use are Bull's Trench Kiln (BTK), based on a design developed by British engineer W. Bull in the late 1800 s. Dry pressed bricks The dry press method is similar to mud brick but starts with a much thinner clay mix, so it forms more accurate, sharper-edged bricks The greater force in pressing and the longer burn make this method more expensive. ranbsingh

Extruded bricks In extruded bricks the clay mix is 20 -25% water This is forced through a die to create a long cable of material of the demanded width and depth This cable is then cut into bricks of the desired length by a wall of wires. The cut bricks are hardened by drying for between 20 and 40 hours at 50 -150 °C before being fired ranbsingh

Fly ash bricks A new brick composed of fly ash and water compressed at 4, 000 psi (27, 939 k. Pa) for two weeks, has been invented recently Owing to the high concentration of calcium oxide in fly ash, the brick can be described as "selfcementing". Solidification takes place under pressure rather than heat It costs 20% less than traditional clay brick manufacture ranbsingh

Influence on fired colour The fired colour of clay bricks is significantly influenced by -the chemical and mineral content of raw materials -the firing temperature and -the atmosphere in the kiln pink coloured bricks - a low iron content white or yellow bricks - a higher lime content Most bricks burn to various red hues ranbsingh

Influence on fired colour (contd. ) If the temperature is increased the colour moves through dark red, purple and then to brown or grey at around 1300 °C Calcium silicate bricks have a wider range of shades and colours Bricks formed from concrete are usually termed blocks, and are typically pale grey in colour Natural stone bricks are of limited modern utility. Only a few stones are suitable for bricks, common materials are granite, limestone and sandstone. Other stones may be used (e. g. marble, slate, quartzite, etc. ) but this tend to be limited to a particular locality ranbsingh

Optimal dimensions and characteristics For efficient handling and laying bricks must be small enough and light enough to be picked up by the bricklayer using one hand (leaving the other hand free for the trowel) Bricks are usually laid flat and as a result the effective limit on the width of a brick is set by the distance which can conveniently be spanned between the thumb and fingers of one hand In most cases, the length of a brick is about twice its width about eight inches ranbsingh

Optimal dimensions and characteristics (contd. ) This allows bricks to be laid bonded in a structure to increase its stability and strength The wall is built using alternating courses of stretchers, bricks laid longways and headers, bricks laid crossways. The headers tie the wall together over its width. The dimensions vary slightly from place to place The ratio for brick dimensions 4: 2: 1 is considered optimal for effective bonding. In the Indus Valley Civilization all bricks corresponded to sizes in a perfect ratio of 4: 2: 1. ranbsingh

Bricks formed from concrete are usually termed blocks, and are typically pale grey in colour Blocks have a much greater range of sizes. Standard coordinating sizes in length and height (in mm) include 400× 200, 450× 150, etc; depths (work size, mm) include 60, 75, 90, etc. They are lighter than clay bricks. The density of solid clay bricks is around 2, 000 kg/m³: this is reduced by frogging, hollow bricks, etc. ; The aerated autoclaved concrete, even as a solid brick, can have densities in the range of 450– 850 kg/m³. ranbsingh

Bricks may also be classified as solid - less than 25% perforations by volume, although the brick may be "frogged, " having indentations on one of the longer faces perforated - containing a pattern of small holes through the brick removing no more than 25% of the volume cellular - containing a pattern of holes removing more than 20% of the volume, but closed on one face, or hollow - containing a pattern of large holes removing more than 25% of the brick's volume Blocks may be solid, cellular or hollow ranbsingh

GRADING OF BRICKS produce of a brick-kiln can be classified as v First class. v Second class. v Third class. v Under burnt or "pilla". v Jhama. v Well-burnt brick-bats. v Under-burnt brick-bats. ranbsingh

Size of bricks Non-metric Unless otherwise specified, bricks required for building or architectural work shall measure 9 " x 4 x 3/8 " x 2 x 11/16" so that every four courses laid shall measure a foot in height A tolerance up to ± 1/4 inch in length ± 1/8 inch in width and ± 1/8 inch in thickness is acceptable A frog 1 inch deep shall be provided on the upper face ranbsingh

Metric Unless otherwise specified, bricks required for building or architectural works shall measure 19 cm x 9 cm (actual) or 20 cm x 10 cm (nominal) so that every 10 courses when laid with horizontal mortar joints shall measure one meter in height. A tolerance up to ± 6. 5 mm in length ± 3 mm in width and ± 3 mm in height is acceptable Every brick shall be provided with a frog of the size 10 cm x 4 cm x 1 cm. The corners of the frog may in certain cases be rounded off with a radius of 2 cm. ranbsingh

SPECIFICATIONS OF BRICKS First Class Bricks The first class bricks shall conform to the following specifications (a) The size of the bricks shall be as specified (b) They shall be made from good brick earth, free from saline deposits and shall be sand molded. (c) They shall be thoroughly burnt without being vitrified and shall have uniform deep red, cherry or copper color (d) They shall be regular and uniform in shape and size with sharp and square arrises and parallel faces (e) They must be homogeneous in texture and emit a clear ringing sound on being struck ranbsingh

First class bricks (contd. ) (f) They shall be free from flaws, cracks, chips, stones nodules or lime or kankar and other blemishes 20 (g) A first class brick shall not absorb water more than per cent of its own dry weight after 24 hours immersion in cold water (h) The first class bricks shall have a minimum crushing strength of 1500 lbs. /sq. inch (105 kg per sq. cm) The crushing strength of any individual brick shall not fall below the average strength by more than 20 per cent (I) First class bricks shall not show appreciable signs of efflorescence either in dry state or subsequent to soaking in water ranbsingh

Second Class Bricks Second class bricks shall conform to the following specifications (a) They shall be well-burnt as first class bricks or slightly over-burnt but not vitrified in any part (b) They must give a clear ringing sound when struck (c) They may have slight irregularities in size, shape and color provided these irregularities are not such as to give uneven courses when used for construction. ranbsingh

Second class bricks (contd. ) (d) They may have slight chips, flaws or surface cracks but must be free from lime or kankar nodules, and be homogeneous in texture. (e) The minimum crushing strength of second class bricks shall be 1000 lb. per sq. inch (70 kg per sq. cm). The crushing strength of any individual bricks shall not fall bellow average strength by more than 20 per cent. (f) They shall not show any appreciable sign of efflorescence either in dry state or subsequent to soaking in water ranbsingh

Third Class Bricks Third class bricks shall conform to the following specifications (a) These need not be so fully burnt as first or second class. These may be slightly under-burnt or slightly over-burnt (b) They may be distorted and have rounded edges and may not be uniform in shape. These defects, however, shall not be such as to cause difficulty in obtaining uniform courses with their use. (c) They shall not absorb water more than 25% of their own dry weight after 24 hours, immersion in cold water. (d) Third class bricks may show moderate signs of efflorescence ranbsingh

Under-burnt or "pilla" Bricks, which remain half-burnt and have a yellowish color These bricks are easily breakable and their use is prohibited, except in sun dried brick work Jhama Bricks are over-burnt Bricks, which get vitrified or distorted so as to be useless for exact work They may be broken up for ballast provided the vitrified mass has not become porous or spongy in the process of being over-burnt ranbsingh

Sun-dried Bricks These shall be made from the same kind of clay as will give good bricks on being burnt. They shall be sand-molded and shall be uniform in size and regular in shape. If after drying, a few bricks picked at random from a batch, break into more than two pieces on being dropped on even ground from a height of about four feet (1. 2 meters), the batch must be rejected as having been molded with too much sand. Batches of bricks in which cracks appear on drying shall be rejected as having been molded with too little sand. Special care shall be taken that the earth used for making sun dried bricks is free from efflorescencing salts and from all traces of white ants. All sun dried bricks shall be thoroughly dried before use. ranbsingh

SAMPLING The samples of bricks should be taken, so that they form a fairly good representative of the entire number of bricks A sample of 50 bricks is taken from every consignment of 50, 000 bricks or part thereof. Sampling Methods (a) Sampling bricks in motion i. e. while they are being loaded or unloaded - samples are collect at regular intervals so as to get a representative sample of the whole quantity (b) Sampling bricks from a stack - the bricks are taken out at random from a stack of bricks. The number of bricks required shall be taken from across the top of the stack, the sides accessible and from the interior of the stack by opening trenches from the top The samples should be stored in a dry place until these are required for the tests. Whenever, tests are to be carried out, bricks shall be taken at random from the sample ranbsingh

Test Procedures Test of Dimensions of Bricks (a) Metric Bricks Twenty whole bricks shall be selected at random from the sample All blisters, loose particles of clay and small projections shall be removed. They shall then be arranged upon a level surface in contact with each other and in a straight line. The over all length of the assembled bricks shall be measured with a steel tape or other suitable inextensible measure sufficiently long to measure the whole row one stretch ranbsingh

Metric Bricks (contd. ) Measurement by repeated application of a short rule or measure should not be permitted. If for any reason it is found impracticable to measure 20 bricks in one row, the sample may be divided into two rows of 10 bricks, which shall be measured separately to the nearest millimeters. All these dimensions shall be added together The dimensions of bricks when tested in accordance with the above procedure shall be within the following limits Length 367. 0 cm to 393. 0 cm. Width and height 174. 0 cm to 186. 0 cm. ranbsingh

Test of Dimensions of Bricks (contd. ) (b) Non - metric Bricks The test should be carried out exactly in the same manner as described for metric bricks, but only 16 bricks shall be used for the test The dimensions of bricks when tested in accordance with the above procedure shall be within the following limits Length 140 inches to 148 inches Width 68 inches to 72 inches Height 57 inches to 61 inches ranbsingh

Tests for determination of Water absorption of bricks (a) Laboratory Test The test specimens shall consist of five whole bricks selected at random from the sample of bricks obtained The test specimen shall be dried to constant weight in a ventilated oven at 110 o. C to 115 o. C. If the specimen is relatively dry this may normally be accomplished in 48 hours but if the specimen is wet, several additional hours may be required to attain constant weight The specimen shall then be cooled approximately to room temperature and weighed. In a ventilated room, bricks properly separated require four hours for cooling unless an electric fan passes air over them continuously, in which case two hours may suffice ranbsingh

Laboratory Test (contd. ) The dry specimens shall be completely immersed without preliminary partial immersion, in clean water at 15. 5 o. C to 30 o. C for 24 hours. Each specimen shall then be removed the surface water wiped off with a damp cloth and the specimen weighed Weighing any one specimen shall be completed within three minutes after removing the specimen from the water The percentage of water absorption by weight shall be calculated as Water absorption, percentage by weight = (W 2 - W 1)/W 1*100 where W 1 = weight of dry specimen, and W 2 = weight after soaking in water The average value of the five specimens shall be taken as the water absorption of the lot. ranbsingh

(b)Field Test The test specimen shall consist of five whole dry bricks and shall be selected at random from the sample obtained. The test specimen shall be weighed and shall then be completely immersed in clean water at room temperature and allowed to remain in this state for a period of 24 hours. The specimen shall then be taken out, wiped with a damp cloth and then weighed immediately. The percentage of water absorption by weight shall be calculated as follows: Absorption, per cent by weight = 100 (b-a)/a Where: a = weight of the dry specimen, and b = weight of the specimen after 24 hours’ immersion in cold water ranbsingh

Maximum Water absorption First class Brick 20% Second class Brick 22% Third class Brick 25% Heavy duty Brick (Machine Made) 5%. ranbsingh

Tests for determination of Efflorescence of bricks (a) Laboratory Test Not less than five dry bricks shall be selected at random from the sample of bricks obtained. Each brick shall be placed on end in a shallow flat bottom dish containing distilled water, the depth of immersion of the brick being not less than 2. 5 cm. The whole arrangement shall be allowed to stand in a warm (e. g. 18 o. C to 30 o. C) and well ventilated room until all the water in the dish evaporated. ranbsingh

Laboratory Test (contd. ) When the water has been absorbed and the bricks appear to be dry, a similar quantity of distilled water shall again be placed in the dishes and the same allowed to evaporate as before. At the end of this period the bricks shall be examined for efflorescence. The liability to efflorescence shall be reported as nil , slight, moderate, heavy or serious, in accordance with the following definitions : (a) nil : When there is no perceptible deposit of efflorescence. (b) slight : When not more than 10 per cent of area of the brick is covered with a thin deposit of salts. ranbsingh

Laboratory Test (contd. ) (c) moderate : When there is heavier deposit covering up to 50 per cent of the area of the brick surface but unaccompanied by powdering of flaking of the surface. (d) heavy : When there is a heavy deposit of salts covering 50 per cent or more of the brick surface but unaccompanied by powdering or flaking of the surface, and (e) serious: When there is a heavy deposit of salts accompanied by powdering and/or flaking of the surfaces and tending to increase with repeated wetting of the specimen. ranbsingh

(b) Field Test for Effloresces Five bricks shall be selected at random from the sample of bricks obtained Each brick shall be placed on end, in a shallow dish containing clean potable water The quantity of water in the dish shall be such that the brick is immersed to a depth of not less than 2. 5 cm (1 inch). The brick shall be allowed to stand in this position for a few days under atmospheric conditions and room temperature until all the water in the dish is evaporated. ranbsingh

Field Test for Effloresces (contd. ) When the water has been absorbed and the bricks appear to be dry, a similar quantity of clean potable water shall be placed in the dishes and the same is allowed to evaporate as before. At the end of this period, the bricks shall be examined for efflorescence The liability to efflorescence be reported as nil, slight, moderate, heavy or serious in accordance with the definition given above ranbsingh

Efflorescence for bricks (as per ASTM) Ten dry full sized bricks shall be tested. The ten specimens shall be sorted into 5 pairs so that both specimens of each pair will have the same appearance as nearly as possible. Keep one set in a drying room by keeping the bricks immersed 1” in water in separate trays and second set in an oven for 7 days. After seven days each set shall be tested. Keep both sets in an oven for three days (Generally 24 hours are sufficient for efflorescence test). Examine both sets from a distance of 10 feet with illuminators of not less than 50 feet candles by an observer with normal vision. If under these conditions no difference is noted report the rating as slightly efflorescence. If a perceptible difference due to efflorescence is noted under these conditions report the rating as Efflorescence. ranbsingh

Tests for determination of Compressive strength of bricks Five whole bricks shall be selected at random from the sample of bricks The bricks shall be immersed in water at 25 o to 29 o. C for 24 hours. They shall then be removed and allowed to drain at room temperature for about five minutes and wiped free from surplus moisture. Their frogs shall be filled with mortar composed of one part Portland cement and one and a half parts clean, coarse sand graded to 0. 3 cm (1/8 inch) and down. ranbsingh

Compressive strength of bricks (contd. ) The bricks shall then be stored under damp sacks for 24 hours. After the expiry of this period, they shall be immersed in water for seven days. At the end of seven days, the samples of bricks shall be taken out, wiped dry and placed with the flat surfaces horizontal and the mortar filled face upwards between 2 three-plywood sheets each approximately 0. 3 cm (1/8 inch) thick and a carefully centered between the plates of the compression testing machine. The compression plate of the testing machine shall have a ball-seating in the form of a portion of a sphere, the center of which coincides with the center of the face plate. ranbsingh

Compressive strength of bricks (contd. ) The load shall be applied axially at the uniform rate of approximately 140 kg per sq. cm per minute until failure occurs. The maximum load at failure divided by the area of bricks shall be taken as the compressive strength. Strength of bricks decreases by 25% when soaked in water. Minimum compressive strength common building bricks 35 kg/sq. cm. Second class bricks 70 kg/sq. cm. First class bricks 105 kg/sq. cm. Sun dried bricks 15 to 25 Kg/sq. cm. AA grade bricks 140 kg/sq. cm. ranbsingh

ASTM Method for compressive strength of bricks Take the sample of brick having length equal to the width with a variation of ± 1 inches. The depression shall be filled with neat Portland cement paste which shall then be aged at least 24 hours before the specimen is capped. Gypsum capping and sulfur filler capping Coat the two opposite flat faces of each specimen with shellac and allow drying thoroughly. Bed one of the dry shellacked faces of the specimen in a three coat of neat paste of calcined gypsum (plaster of Paris) that has been spread on an oiled non absorbent plate such as glass or machined metal. Repeat this procedure with the other dry shellacked face. Take care that the opposite bearing surfaces so formed will be approximately parallel and thickness of the cap will be approximately same. Age the cap at least 16 hours before testing the specimen. ranbsingh

Brick Ballast Bricks ballast shall be broken to the gauge specified, from first or second class bricks or their bats, or from dense over burnt bricks No under-burnt brick bats or jhama that has become spongy or porous in the process of burning, shall be broken up for ballast The ballast shall be clean and free from surkhi, leaves, straw, earth, sand or other foreign matter To avoid mixing up of impurities, the ballast should be broken and stacked on a clean platform ranbsingh

Brick Ballast (contd. ) One and half inch (38 mm) gauge bricks ballast shall be such as to completely pass through a ring of 1½ inch (38 mm) internal diameter Not more than 20 per cent shall be more than 2 inch (51 mm) in greatest length If an unduly large proportion of fine stuff is there the ballast may be screened through a 3/4"x 3/4" (19 mm x 19 mm) square mesh screen, if more than 15 per cent of the materials pass this screen it is not acceptable. One and a quarter inch (32 mm) gauge brick ballast shall be such as to completely pass through a ring of 1¼ inch (32 mm) internal diameter. ranbsingh

Brick Ballast Contd. ) Not more than 20 per cent shall be larger than 1½ inch (38 mm) in the greatest length If an unduly large proportion of fine stuff is there the ballast may be screened through a 5/8"x 5/8" (16 mm x 16 mm) square mesh sieve, if more than 15 per cent of the material pass this sieve it is not acceptable. 3/4 inch (19 mm) gauge brick ballast shall be such as to completely pass through a ring of 3/4"x 3/4" (19 mmx 19 mm) square mesh Not more than 20 per cent shall be larger than 1 inch (25. 0 mm) in the greatest length. The ballast is screened to ensure that not more than 15 per cent passes through a sieve of 3/8" x 3/8” (9. 5 mm x 9. 5 mm) square mesh. ranbsingh

Pozzolana also known as pozzolanic ash, is a fine, sandy volcanic ash ranbsingh

Pozzolana, also known as pozzolanic ash, is a fine, sandy volcanic ash, originally discovered and dug in Italy at Pozzuoli. It is found in all the volcanic areas of Italy in various colours: black, white, grey and red. Pozzolana is a siliceous and aluminous material which reacts with calcium hydroxide in the presence of water to form compounds possessing cementitious properties at room temperature. Finely ground and mixed with lime it creates a hydraulic cement and can be used to make a strong mortar that will also set under water. It transformed the possibilities for making concrete structures. Typically it was mixed two-to-one with lime just prior to mixing with water. ranbsingh

Gypsum is a very soft mineral composed of calcium sulfate dihydrate, with the chemical formula Ca. SO 4· 2 H 2 O Plaster of Paris, or simply plaster, is a type of building material based on calcium sulfate hemihydrate. It is created by heating gypsum to about 150 °C. 2 Ca. SO 4· 4 H 2 O → 2 Ca. SO 4·H 2 O + 3 H 2 O (released as steam). A large gypsum deposit at Montmartre in Paris is the source of the name. When the dry plaster powder is mixed with water, it re-forms into gypsum. Unlike mortar and cement, plaster remains quite soft after drying, and can be easily manipulated with metal tools or even sandpaper. These characteristics make plaster suitable for a finishing, rather than a load-bearing material. ranbsingh

Fly ash is the finely divided mineral residue resulting from the combustion of coal in electric generating plants. Fly ash consists of inorganic, incombustible matter present in the coal that has been fused during combustion into a glassy, amorphous structure. Fly ash material solidifies while suspended in the exhaust gases and hence, the fly ash particles are generally spherical in shape and range in size from 0. 5 µm to 100 µm. They consist mostly of silicon dioxide (Si. O 2), aluminium oxide (Al 2 O 3) and iron oxide (Fe 2 O 3). They are also pozzolanic in nature and react with calcium hydroxide and alkali to form calcium silicate hydrates (cementitious compounds). ranbsingh

There aretwo classes of fly ash ; Class F fly ash and Class C fly ash. The chief difference between these classes is the amount of calcium, silica, alumina, and iron content in the ash. Class F fly ash The burning of harder, older anthracite and bituminous coal typically produces Class F fly ash. This fly ash is pozzolanic in nature, and contains less than 10% lime (Ca. O). Possessing pozzolanic properties, the glassy silica and alumina of Class F fly ash requires a cementing agent, such as Portland cement, quicklime, or hydrated lime, with the presence of water in order to react and produce cementitious compounds. ranbsingh

Class C fly ash Fly ash produced from the burning of younger lignite or subbituminous coal. In addition to having pozzolanic properties, also has some selfcementing properties. In the presence of water, Class C fly ash will harden and gain strength over time. Class C fly ash generally contains more than 20% lime (Ca. O). Unlike Class F, self-cementing Class C fly ash does not require an activator. Alkali and sulfate (SO 4) contents are generally higher in Class C fly ashes. ranbsingh

Fly ash - Chemical composition and classification Component Bituminous Sub-bituminous 40 -60 Lignite Si. O 2 (%) 20 -60 15 -45 Al 2 O 3 (%) 5 -35 20 -30 20 -25 Fe 2 O 3 (%) 10 -40 4 -15 Ca. O (%) 1 -12 5 -30 15 -40 LOI (%) 0 -15 0 -3 0 -5 ranbsingh

Cement chemist notation (CCN) was developed to simplify the formulas which cement chemists use on a daily basis. It is a sort of "short hand" way of writing the chemical formula of oxides of calcium, silicon, and various metals. Below is a list of all of the abbreviations used: CCN Actual Formula C Ca. O M Mg. O S Si. O 2 K K 2 O A Al 2 O 3 N Na 2 O F Fe 2 O 3 H H 2 O T Ti. O 2 CO 2 SO 3 ranbsingh

The oxides are used to build complex molecules such as C 3 S C 2 S C 3 A 3 Ca. O • Si. O 2 Tricalcium silicate 2 Ca. O • Si. O 2 3 Ca. O • Al 2 O 3 Dicalcium silicate Tricalcium aluminate C 4 AF 4 Ca. O • Al 2 O 3 • Fe 2 O 3 Tetracalcium alumino ferrite ranbsingh

Hydration products are more complicated • • many of the products have nearly the same formula some are solid-solutions with overlapping formula Some examples are below: CSH CAH AFt AFm 2(Ca. O) • Si. O 2 • 0. 9 -1. 25(H 2 O) and/or Ca. O • Si. O 2 • 1. 1(H 2 O) and/or 0. 8 -1. 5(Ca. O) • Si. O 2 • 1. 0 -2. 5(H 2 O) and more! This is even more complex than CSH C 3 A 3 H 30 -32 C 2 A H 12 ranbsingh