Chap16 cbm&cw
- 2. CONCRETE BLOCK MASONARY Solid and hollow concrete blocks are manufactured to meet the growing requirement of building blocks in towns and cities. They are manufactured with lean mixes of cement , sand and aggregates of size less than 12mm. The size of solid concrete block is 400x200x150 mm (normal size). The minimum strength prescribed is 4N/MM.SQ.The block should have sharp edges and right angled corners. Hollow block of normal sizes 400x200x190mm and 400x300x190mm are manufactured. The net area of hollow block is 55-60% of the gross area.They should have sharp edges and right-angled corners.
- 3. CONCRETE BLOCK MASONARY Hollow concrete blocks
- 4. Advantages of using concrete block is: 1. Construction is fast, as the size of the block is large and the mortar required is less. 2. To build a 1m.sq. and thickness 200mm, only 10 blocks are required as against 115clay bricks. It needs only 13 liters of cement mortar as against 45 liters required in brick masonry.
- 5. Concrete blocks may be given the following surface finishes a) Coarse textured b) Glazed finish c) Slumped finish d) Specially faced finish e) Colored finish
- 6. Construction of walls with concrete bock masonry The construction method for concrete block walls is exactly the same as that for brick masonry. First, corners or ends are built to a few courses, followed by the middle portion. Vertical joints are broken. The final closing block needs to be fitted carefully.
- 7. The following points need to be observed in concrete block masonry Blocks should be dry before use. Vertical joints should be broken. Mortar used should not be stronger than the block itself. The preferable mortar is 1:1:10 cement-lime-sand mix. The joints should be 5-10mm thick. The blocks used for external walls should have absorption less than 10%. For internal walls, adsorption up to 15% may be permitted. Solid concrete blocks or hollow blocks filled with site concrete should because in the junction of walls and also in the middle of long walls to avoid cracking due to expansion
- 8. Concrete blocks used in building construction
- 9. STONE COMPOSITE MASONRY Stone composite masonry is constructed with stone and one or more combinations of materials, like stone facing and brick backing or stone facing and concrete backing. Stone composite masonry is of different types, each having its own properties. To make use of both ashlar and rubble, composite masonry may be used. In such masonry, the facing is with ashlar masonry, while the backing is with rubble masonry
- 10. STONE COMPOSITE MASONRY FIELD STONE (RUBBLE) STONE COMPOSITE MASONRY
- 11. BRICK-STONE COMPOSITE MASONRY RUBBLE-BACKED BRICK MASONRY BRICK-BACKED ASHLAR MASONRY BRICK-BACKED STONE SLAB MASONRY
- 12. RUBBLED-BACKED BRICK MASONRY The facing is of brick masonry, while the backing is of rubble stone masonry. This type of composite masonry is commonly adopted in locations where stone is available locally in large quantities.
- 13. BRICK-BACKED ASHLAR MASONRY In this type the facing is of ashlar stone masonry, while the backing is of brick masonry. It is used where skilled labor and beautiful stones are available. The stones thickness should be such that multiple layers of bricks match it. Care should be taken to break vertical joints. Cement mortar is preferred for such masonry.
- 15. BRICK-BACKED STONE SLAB MASONRY The facing is granite or marble and the backing is of bricks. It is preferable to use metal cramps to connect the facing and backing.
- 16. REINFORCED BRICK MASONRY Ordinary brick masonry cannot take tensile stresses because bricks get pulled apart at the mortar joints. In such situations brick masonry is reinforced by steel bars or expanded bars. Reinforced brick works are commonly used in lintels, retaining walls, walls built on soil that is susceptible to large settlement and in seismic zones. Sometimes, brick columns are strengthened with bars to increase their compressive load-carrying capacity.
- 18. TYPES OF MASONRY BONDS
- 19. Reinforced brick works may be grouped into: REINFORCED BRICK LINTELS REINFORCED BRICK COLUMNS REINFORCED BRICKWALLS REINFORCED BRICK SLABS
- 20. REINFORCED BRICK LINTELS The reinforcement consists of 6-12mm diameter while vertical stirrups are 6mm in diameter. The vertical stirrups are at every third joint.
- 23. REINFORCED BRICK COLUMNS By reinforcing the load carrying capacity of the column is increased. For this construction special type of bricks are used which have grooves for vertical reinforcement. At every fourth course, they are provided with horizontal steel plates of 6mm thickness. Vertical steel bars are fixed in the foundation concrete block.
- 25. REINFORCED BRICK WALLS Walls that are likely to be subject to tensile are reinforced. The reinforcement required is horizontal and vertical. Horizontal reinforcement is provided at every third or fourth course. It consists of steel mesh spread flat on the cement mortar and pressed uniformly. It consists of 20-30mm wide steel flats of thickness 1.5- 2.0mm. These flats are dipped in molten tar to increase their resistance against rusting and then immediately sanded. Generally one strip is provided for every thickness of half a brick.
- 26. REINFORCED BRICK WALLS Reinforcement in vertical direction is provided by using special bricks that have grooves to pass the bars. Mild steel bars of 6mm diameter are used as vertical reinforcement. They are tied at suitable intervals with fine wires Bricks with grooves
- 27. REINFORCED BRICK SLABS If bricks are to be used for the construction of slab, they should be reinforced with steel. In such construction a wooden platform is built which is covered with well beaten earth. Then fine sand is sprinkled over which mortar layer is spread and reinforcement is embedded. Specially bricks with grooves are then laid in one or two courses.The joints are filled with mortar. The slab is cured for three to four weeks.The top and bottom surfaces are suitably finished.
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