BRICKS BRICKS v One of the oldest construction

BRICKS

BRICKS : v. One of the oldest construction material v Most popular and leading construction material REASON: ØLow cost ØDurable ØLight weight ØEasy to work with

ADVANTAGES OVER STONES: ØLight weight ØUniform shape and size ØMoulded to required size ØEasy laying ØCheaper ØFire resistance ØThinner sections ØLess mortar for bonding ØEasy transportation ØProduced in large quantities

RAW MATERIALS: Sl. CONSTITU No. ENT % FUNCTION EXCESS QTY. LEADS TO 1 Clay 20 to 30 Plasticity Shrinkage 2 Sand 50 to 60 Prevents cracking and shrinkage Brittleness 3 Lime 10 Prevents shrinkage Helps binding Swells and disintegrate 4 Iron oxide 4 to 5 Gives red colour Becomes dark blue 5 Magnesia Small Imparts yellow tint quantity and decreases shrinkage Decay of bricks

MANUFACTURE OF BRICKS: ØPreparation ØMoulding ØDrying ØBurning

PREPARATION: ØUpper layer removed ( free from vegetation, gravel and lime) ØClay exposed to atmosphere in wet condition ØClay mixed with ingredients to become homogeneous and attain uniform colour ØClay mix kneaded for moulding

MOULDING: ØSteel or wooden moulds ØOpen both at top and bottom ØPrepared according to size of brick ØClay mix filled in the mould, levelled and excess qty. is removed. ØMould is lifted up and the procedure is repeated.

DRYING: ØMoulded bricks are stacked in layers ØDried for about 6 weeks (depending on weather condition) BURNING: ØClamps (or) Kilns are used to burn ØStacked and burnt at about 8000 C using coal, firewood etc. ØBurning imparts strength and hardness ØIt should be properly burnt ØOver-burnt leads to brittleness ØUnder-burnt leads to softness and hence less load carrying capacity

USES: üWalls, Bridges, Dams and Culverts üPavements, Kerbs Partitions and roads üFire bricks used for fire resisting structures üOrnamental works üPerforated and hollow bricks for heat insulation üCompound walls, Columns, Stairs and Arches üBroken pieces for weathering courses

CLASSIFICATION: BASED ON THE MANUFACTURING PROCESS ØFIRST CLASS BRICKS ØSECOND CLASS BRICKS ØTHIRD CLASS BRICKS ØFOURTH CLASS BRICKS

FIRST CLASS BRICKS: üSmooth and rectangular üParallel, sharp and straight edges üThoroughly burnt with deep red colour üUniform texture üWater absorption 12% to 15% of its dry weight when immersed in cold water for 24 hrs üMettallic (or) Ringing sound by striking üCrushing strength not less than 10. 5 N/mm 2

SECOND CLASS BRICKS: üSmall cracks are allowed üWater absorption 16% to 20% üCrushing strength not less than 7 N/mm 2 üUSES: all masonry works THIRD CLASS BRICKS: üUnder burnt üSoft and light üDull sound üWater absorption is 25% üUSES: Temporary structures FOURTH CLASS BRICKS: ØOver burnt ØBad shape and size Øbrittle

BASED ON COMPRESSIVE STRENGTH (AS PER ISI) [ IS 1077 -1976 ] CLASS AVERAGE COMPRESSIVE STRENGTH (N/mm 2) 350 35 300 30 25 200 20 175 17. 5 150 15 12. 5 100 10 75 7. 5 50 5 35 3. 5

SIZE AND WEIGHT: Ø 19 cm x 9 cm Ø 20 cm x 10 cm (including mortar) Ø 3 to 3. 5 kg

QUALITY OF GOOD BRICKS: Shape and size Uniform with straight edges Colour Deep RED Texture and Compactness No fissures and holes Hardness and Soundness No finger nail impression Compressive strength [ 10. 5 N/mm 2] Water absorption [ Not more than 20%] Density [ 17 to 19 k. N/m 3 ] Shear strength 5 To 7 N/mm 2 Fire Resistance High Soluble salts Free Breakage When dropped from 1 m height it should not break.

TESTS ON BRICKS: IS 3495 - 1976 1. COMPRESSIVE STRENGTH üBoth faces made smooth üImmersed in water for 24 hrs for three days üThe specimen is then placed between the plates of the compression testing machine üLoad is applied axially at a uniform rate 14 N/mm 2 and maximum load at which the specimen fails is noted for determination of compressive strength not less than 3. 5 N/mm 2 üAgain immersed in clean water for 3 days Compressive strength = testing Load atmachine. failure/ Area of the cross section of üTested in compression

2. WATER ABSORPTION TEST: üDry brick weighed (W 1) üImmersed in water for 24 hrs üAgain weighed (W 2) üPercentage of water absorption = [W 2 – X 100 W 1] W 1

3. EFFLORESCENCE TEST: üBricks placed in water of 2. 5 cm depth till water is absorbed or evaporated üAfter drying again placed in water üExamined for efflorescence Efflorescence is classified as follows: Nil 0% Slight 10% Moderate 10 to 50% Heavy more than 50%

Thank You. , PRESENTED BY. , Aravinth M