BRICKS

One of the oldest construction material BRICKS : One of the oldest construction material Most popular and leading construction material REASON: Low cost Durable Light weight Easy to work with

ADVANTAGES OVER STONES: Light weight Uniform shape and size Moulded to required size Easy laying Cheaper Fire resistance Thinner sections Less mortar for bonding Easy transportation Produced in large quantities

RAW MATERIALS: Sl.No. CONSTITUENT % 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 quantity Imparts yellow tint and decreases shrinkage Decay of bricks

MANUFACTURE OF BRICKS: Preparation Moulding Drying Burning

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

MOULDING: Steel or wooden moulds Open both at top and bottom Prepared according to size of brick Clay mix filled in the mould, levelled and excess qty. is removed. Mould is lifted up and the procedure is repeated.

DRYING: Moulded bricks are stacked in layers Dried for about 6 weeks (depending on weather condition) BURNING: Clamps (or) Kilns are used to burn Stacked and burnt at about 8000 C using coal, firewood etc. Burning imparts strength and hardness It should be properly burnt Over-burnt leads to brittleness Under-burnt leads to softness and hence less load carrying capacity

USES: Walls, Bridges, Dams and Culverts Pavements, Kerbs Partitions and roads Fire bricks used for fire resisting structures Ornamental works Perforated and hollow bricks for heat insulation Compound walls, Columns, Stairs and Arches Broken pieces for weathering courses

CLASSIFICATION: BASED ON THE MANUFACTURING PROCESS FIRST CLASS BRICKS SECOND CLASS BRICKS THIRD CLASS BRICKS FOURTH CLASS BRICKS

FIRST CLASS BRICKS: Smooth and rectangular Parallel, sharp and straight edges Thoroughly burnt with deep red colour Uniform texture Water absorption 12% to 15% of its dry weight when immersed in cold water for 24 hrs Mettallic (or) Ringing sound by striking Crushing strength not less than 10.5 N/mm2

SECOND CLASS BRICKS: THIRD CLASS BRICKS: FOURTH CLASS BRICKS: Small cracks are allowed Water absorption 16% to 20% Crushing strength not less than 7 N/mm2 USES: all masonry works THIRD CLASS BRICKS: Under burnt Soft and light Dull sound Water absorption is 25% USES: Temporary structures FOURTH CLASS BRICKS: Over burnt Bad shape and size brittle

AVERAGE COMPRESSIVE STRENGTH (N/mm2) BASED ON COMPRESSIVE STRENGTH (AS PER ISI) [ IS 1077-1976 ] CLASS AVERAGE COMPRESSIVE STRENGTH (N/mm2) 350 35 300 30 250 25 200 20 175 17.5 150 15 125 12.5 100 10 75 7.5 50 5 3.5

SIZE AND WEIGHT: 19 cm x 9 cm x 9 cm 20 cm x 10 cm x 10 cm (including mortar) 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/mm2] Water absorption [ Not more than 20%] Density [ 17 to 19 kN/m3 ] Shear strength 5 To 7 N/mm2 Fire Resistance High Soluble salts Free Breakage When dropped from 1m height it should not break.

TESTS ON BRICKS: IS 3495- 1976 1. COMPRESSIVE STRENGTH Both faces made smooth Immersed in water for 24 hrs for three days The specimen is then placed between the plates of the compression testing machine Load is applied axially at a uniform rate 14 N/mm2and maximum load at which the specimen fails is noted for determination of compressive strength not less than 3.5 N/mm2 Again immersed in clean water for 3 days Tested in compression testing machine. Compressive strength = Load at failure/ Area of the cross section of the brick

2.WATER ABSORPTION TEST: Dry brick weighed (W1) Immersed in water for 24 hrs Again weighed (W2) Percentage of water absorption = [W2 – W1] W1 X 100

3.EFFLORESCENCE TEST: Bricks placed in water of 2.5 cm depth till water is absorbed or evaporated After drying again placed in water Examined 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