2Bricks are obtained by moulding clay in rectangular blocks of uniform size and then by drying and burning these blocks.As bricks areof uniform size,they can be properly arranged,light in weightreplace stones
3Jetavanaramaya stupa in Anuradhapura, Sri Lanka is one of the largest brick structures in the world.
4The world's highest brick tower of St The world's highest brick tower of St. Martin's Church in Landshut, Germany, completed in 1500
5The brickwork of Shebeli Tower in Iran displays 12th century craftsmanship Chile house in Hamburg, Germany
6Size of Brick used Size of the Brick Standard size 19cm X 9cm X 9cm Nominal size 20cm X 10cm X 10cmNominal size is the thikness of motar with brick size
7CLASSIFICATION OF BRICKS First class bricks:These bricks are table-moulded and of standard shape and they are burnt in kilns.The surfaces and edges of the bricks are sharp, square, smooth and straight.These bricks are used for superior work of permanent nature.
8Second class bricks:are ground-moulded and they are burnt in kilns.The surface of these bricks is somewhat rough and shape is also slightly irregular.These bricks may have hair cracks and their edges may not be sharp and uniform.These bricks are commonly used at places where brickwork is to be provided with a coat of plaster
9Third class bricks:ground-moulded and they are burnt in clamps.not hard and they have rough surfaces with irregular and distorted edges.give dull sound when struck together.used for unimportant and temporary structures and at places where rainfall is not heavy.
10Fourth class bricks:These are over burnt with irregular shape and dark color.These bricks are used as aggregate for concrete in foundations, floors, roads, etc.the over burnt brick have a compact structure ----sometimes found to be stronger that even the first class bricks.
11Composition Following are the constituents of good brick earth. Aluminachief constituent of clayA good brick earth should contain 20 to 30 percent of alumina.imparts plasticity to earth moulded.If alumina is present in excess, raw bricks shrink and warp during drying and burning.
122. SilicaA good brick earth should contain about 50 to 60 percent of silica.Silica exists in clay either as free or combined form.Presence of silica prevents crackers, shrinking and warping of raw bricks.It thus imparts uniform shape to the bricks.
133. LimeA small quantity in finely powdered state prevents shrinkage of raw bricks.Excess of lime causes the brick to melt and hence, its shape is lost due to the splitting of brick
144. Oxide of ironA small quantity of oxide of Iron -- 5 to 6 percent is desirable in good brick to imparts red colour to bricks.Excess of oxide of iron makes the bricks dark blue or blackish.
155. MagnesiaA small quantity of magnesia in brick earth imparts yellow tint to bricksdecreases shrinkage.excess of magnesia leads to the decay of bricks.The ingredients like, lime, alkalies, pebbles, organic matter should not present in good brick earth
16Manufacture of bricks: The manufacturing of brick, the following operations are involvedSite selectionPreparation of brick earthMoulding of brickDrying of bricksBurning of bricksUnsoilingDiggingCleaningWeatheringGrindingBlendingTempering
17Selection of siteMust have suitable clayIn sufficient quantityLocation---water table should be atleast 1m below kiln floor
18(ii) Preparation of clay :- The preparation of clay involvesfollowing operationsUnsoilingTop layer of 20cm depth is removed as it contain impurities-organic matter, roots.DiggingClay is dug out from ground and spread on level ground about 60cm to 120cm heaps.CleaningStones, pebbles, vegetable matter etc removed and converted into powder form.
20WeatheringClay is exposed to atmosphere from few weeks to full season.Grindinghard clay with lumps are crushed in clay crushing rollersBlendingClay is made loose and any ingradient to be added to it is spread out at top and turning it up and down in vertical directionTemperingClay is brought to a proper degree of hardness,then water is added to clay andwhole mass is kneaded or pressed under the feet of men or cattle for large scale,done in pug mill
22iii) Moulding of bricks Hand or machine Mould- Rectangular boxes open at bottom Wood or steel
23Hand mouldingGround is levelledSprinkle fine sandDip mould in water and place on grndLumps of clay are dashed in to itPressed and filled----fill cornersSurplus clay removed by using a strickerMould is lifted upRaw brick remains
25Machine mouldingWhen,-large scale productionClay is hardPlastic clay machine---wire cut bricksDry clay machine---powdered clay filled in moulds ---pour water----pressed----results in hard, well shaped
26DryingThe damp bricks, if burnt, are likely to be cracked and distorted.Hence moulded bricks are driedBricks are laid along and across the stock in alternate layers.5-7 % moisture contentMostly natural or artificial drying
27Burning:to impart hardness, strength and makes them dense and durable.Burning --- clamps or in kilns.Clamps are temporary structures and to manufacture bricks on small scale.Kilns are permanent structures and they are adopted to manufacture bricks on a large scale.
30ClampTemporary structuresStacked in layers with gaps for firewood6-8 weeksStrong tough bricksQuality not uniformNo skilled labourKilnsMasonry structures ----permanentContinuousUniform qualityNeed skilled labour
31Qualities of Good Brick Bricks should be table moulded,well burnt in kilns, copper coloured,free from cracks andwith sharp and square edgesuniform shape and should be of standard sizeclear ringing sound when struck each other
32bright homogeneous and compact structure free from voids should not absorb water more than 20 percent by weight for first class bricks22 percent by weight for second class brickswhen soaked in coldwater for a period of 24 hours
33Tests on bricksA brick is generally subjected to following tests to find out its suitability of the construction work.Compressive strengthAbsorptionHardnessPresence soluble saltsShape and sizeSoundnessStructureA good should not absorb not more than 20 percent of weight of dry brick
34Compressive strength: Smooth the surface, immerse in water for 24 hrsin compression testing machineIt is pressed till it 14 N/mm2 per minuteCompr strength = max load at failure/loaded area of brick
35AbsorptionOven dried for C270 C for 24 hrsA good should not absorb not more than 20 percent of weight of dry brick %water absorption = ((w2-w1)/w1) X 100HardnessScratch with finger nail -- No impression is left on the surface the brick is treated to be sufficiently hard
36Presence of soluble salts (efflorescence) The bricks should not show any grey or white deposits after immersed in water for 24 hours (HW)Shape and sizeIt should be standard size and shape with sharp edges
37SoundnessThe brick should give clear ringing sound struck each otherStructureThe structure should be homogeneous, compact and free from any defects
38Measure greatest distance using the rule WarpageMeasured withFlat surface of steel/glassSteel measuring ruleClean the surfacePlace on the flatMeasure greatest distance using the rule