Brick is widely used for boundary wall, partition wall, soling work all over the world and sub-base material for road work & as a course aggregate material for concrete work in South Asian region.
Types of Brick:
- First class bricks: This type of bricks shall be made from good brick earth, free from saline deposits, and shall be sand-molded. They shall be thoroughly burnt by coal without being vitrified, of uniform and good color, shall be regular and uniform in size, shape and texture with sharp square edges and parallel faces. They must be homogeneous in texture and emit a clear metallic ringing sound when struck one against the other. They shall be free from flaws, cracks, chips, stones, modules of lime or kankar and other blemishes. First class bricks should have the following dimensions after burning: 242 mm x 115 mm x 70 mm. Average compressive strength of 1st class brick shall not less than 17 MPa. The unit weight of 1st class bricks shall not be less than 1,100 kg/m3. A first class brick shall not absorb more than 1/6th of its weight of water after being soaked for one hour, and shall show no sign of efflorescence on drying.
- Jhama bricks: Jhama bricks are those which are so over burnt as to become vitrified or distorted, so as to be unsuitable for precise brickwork. Jhama bricks may be broken and used for aggregate in roadwork. Selected Jhama bricks which may have dimensions slightly below those for other classes of brick but not less than 235 mm x 110 mm x 70 mm may be used in brickwork. The unit weight of Jhama bricks shall not be less than 1,200 kg/m3. Minimum compressive strength shall be 20 MPa for Jhama Bricks.
- Perforated bricks: Perforated bricks shall be of uniform size and color with sharp edges, square and parallel faces and have a standard number of perforations. They must be standard commercial products of approved manufactures.
- Machine made pressed bricks: The Machine made pressed bricks dimension shall be vary depends upon the manufacturers. The use of machine made pressed bricks depends upon project requirement.
Cement: Portland Composite Cement (PCC) is best for brick mortar work. Ordinary Portland Cement (OPC) also be used in brickwork.
Fine aggregate: The fineness modulus of sand shall not be less than 1.50 for brick works and for filler material for brick flat soling shall be greater than 1.0.
Water: Fresh or suitable water shall be used. The water cement ratio of brickwork shall not be greater than 0.5.
Mortar for brickwork: Mortar for brickwork shall consist of a mixture of one part by weight of cement to six parts by weight of sand for brickwork of width 250 mm or more and one part by weight of cement to four parts by weight of sand for brickwork of width less than 250 mm. The cement and sand shall be mixed dry and in the specified proportion until the color of the mixture is uniform. Fresh water shall then be added sparingly, only the minimum necessary being used to produce a workable mixture of normal consistency. The water/cement ratio shall in no case exceed 50% by weight. The mixing shall be done on a clean board or platform with tied joints, to avoid leakage. At the close of each day’s work the mixing trough and pans shall be thoroughly cleaned. Cement mortar shall be mixed in such quantities as can be used in the work within 30 minutes. Mortar, which has taken initial set, shall not be used nor shall it be remixed with fresh mortar and such mortar shall be discarded and removed from the working site.
Brickwork shall be built plumbed, curved or battered as shown on the working drawings or as may be required, by properly supervised skilled masons and workmen. Bricks shall be cleaned and if necessary, they shall be scrubbed. Bricks shall be soaked in water for at least three hours before use.
All face work bricks shall be specially selected regarding size, shape and edges. All horizontal joints shall be parallel and level. Vertical joints in alternate courses shall come directly over one another. Joint thickness shall be 6 mm and shall in no case exceed 8 mm. The height of four courses including 4 bed joints shall rise 300 mm except for corners, walls shall always be carried up regularly along their entire length throughout the structure. The brickwork shall be cured for at least seven days. Fixtures such as clamps, pipe brackets, etc.; shall be built into the brickwork during execution.
The bricks shall be laid flat on a 75 mm thick compacted sand cushion layer over the prepared sub-grade or improved sub-grade surface. Bricks shall be laid in a regular and uniform manner. Interstices of bricks shall be filled with sand, and water shall be applied by sprinkling. No bricks shall be laid on loose earth or earth filling which has not been compacted to the required density.