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Properties of Bricks

Properties of Bricks The following are the required properties of good bricks: (i) Colour: Colour should be uniform and bright. (ii) Shape: Bricks should have plane faces. They should have sharp and true right angled corners. (iii) Size: Bricks should be of standard sizes as prescribed by codes. (iv) Texture: They should possess fine, dense and uniform texture. They should not possess fissures, cavities, loose grit and unburnt lime. (v) Soundness: When struck with hammer or with another brick, it should produce metallic sound. (vi) Hardness: Finger scratching should not produce any impression on the brick. (vii) Strength: Crushing strength of brick should not be less than 3.5 N/mm2. A field test for strength is that when dropped from a height of 0.9 m to 1.0 mm on a hard ground, the brick should not break into pieces. (viii) Water Absorption: After immercing the brick in water for 24 hours, water absorption should not be more than 20 per cent by weight. For class-I work...
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LIME

LIME It is an important binding material used in building construction. Lime has been used as the material of construction from ancient time. When it is mixed with sand it provides lime mortar and when mixed with sand and coarse aggregate, it forms lime concrete. Types of Limes and their Properties The limes are classified as fat lime, hydraulic lime and poor lime: (i) Fat lime: It is composed of 95 percentage of calcium oxide. When water is added, it slakes vigorously and its volume increases to 2 to 2 1/2 times. It is white in colour. Its properties are: (a) hardens slowly (b) has high degree of plasticity (c) sets slowly in the presence of air (d) white in colour (e) slakes vigorously. (ii) Hydraulic lime: It contains clay and ferrous oxide. Depending upon the percentage of clay present, the hydraulic lime is divided into the following three types: (a) Feebly hydraulic lime (5 to 10% clay content) (b) Moderately hydraulic lime (11 to 20% clay content) (c) Emin...
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MUD MORTAR

Clay lumps are collected and are wetted with water and allowed to mature for 1 or 2 days. It is kneeded well until it attains required consistancy. Sometimes fibrous materials like gobber is added in the mix. It prevents cracks in the plaster. If plaster is to be used for outer walls, it is sprayed or painted with bitumen. It is cheap mortar. Its durability is less. It is normally used for the construction of temporary sheds and cheap houses in rural areas.
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