SPECIFICATION ON BRICKWORK AND CONCRETE

If you want know about Dpc and water proofing or Introduction of pile foundation or Types of concrete and its uses or Types of foundation or Types of footing please click the link above.


1) Brickwork

SPECIFICATION ON BRICKWORK
  • A  structure, such as a wall, built of bricks. or The  work of laying bricks. or Work of or with bricks and mortar.
  • So,     Brickwork = Bricks + Mortar
  • Mortar = Cement + sand + water or Mortar = Cement + fine aggregate + water
  • Concrete = cement + fine agg. + coarse agg. + water

2) Bricks

  • All bricks shall be of first class of standard specifications made of good brick earth thoroughly burnt, and shall be of deep cherry red of copper color.
  • Bricks shall be regular in shape and their edges should be sharp and square and shall emit clear ringing on being struck and shall be free from cracks, chips, flaws and lumps of any kind.
  • Brick shall not absorb water more than one‑sixth of their weight after one hour of soaking by immersing in water.
  • Bricks shall have a minimum crushing strength of 105kg/sqcm

3) Mortar = Cement + sand + water

i) Cement

  • Grade of Ordinary Portland cement to be used.
  • Compressive strength of the cement After different time – 3days, 7 days and 28 days
  • Setting time – initial setting time > 30 minutes and final setting time < 600 minutes

ii) Sand/fine aggregate

  • Passes through 4.75mm IS sieve
  • Should be inert, clean and free from organic matter.
  • Type of sand to be used such as fine sand, coarse sand, stone dust, surkhi, etc.
  • Dry sand to be used. If sand is wet then the volume of sand should be increased due to bulking of sand.

iii) water

  • Water used for mixing and curing shall be clean and as good as drinking water.
  • Potable water is generally considered satisfactory for mixing. The pH value of water should be not less than 6.

4) Mortar mixing

i) Mechanical mixing

  • Cement and sand in specified proportions shell be mixed dry thoroughly in the mixer.
  • Water shall be added gradually and wet mixing continued for at least 3 minutes.
  • Mixer shall be cleaned with water each time before suspending the work

ii) Hand mixing

  • Measured quantity of sand shall be levelled on clean masonry platform and put required amount of cement on top of sand.
  • Thoroughly mixed dry till the mixture is of uniform colour.
  • Then mixed with sufficient quantity of water.
Note : Mortar should be used with in 30 minutes, before it begins to set.

5) Laying of mortar + bricks

  • Bricks shall be well bounded and laid in English bond unless otherwise specified.
  • Every course shall be truly horizontal (level and alignment) and in plumb.
  • Vertical joints of consecutive course shall not come directly over one another.
  • No damaged or’ broken bricks‑ shall be used except as closer where necessary to complete the bond
  • Bricks shell be laid on full bed of cement mortar(1:5), when laying shall be properly bedded.
  • Joints shall be fully filled and packed with mortar.
  • Mortar joints shall not exceed 12 mm thickness and joints shall be fully filled with mortar.
  • Bricks shall be laid with frogs upward except in the top course where frogs shall be placed downward.
  • Brickwork shall be carried out not more than 3 ft height at a time.

6) Finishing of joints ( mortar + bricks )

  • The face of the brick work may be finished flush or by pointing,
  • The face of brick work shall be cleaned with wire brush.

7) Curing of brickwork

  • The brickwork shall be constantly kept moist on all faces for at least 7 days after laying.

8) Measurements of brickwork

  • Brickwork shall be measured in cu m.
  • Different kinds of brickwork with different mortar shall be taken under separate items.
  • The thickness of wall shall be taken as multiple of half brick as half brick 10 cm, I brick 20 cm, 1&1/2 brick 30 cm and so on.
  • The rate shall be for the complete work including scaffolding and all tools and plants.

9) Concrete = cement + fine agg. + coarse agg. + water

  • Cement – done above
  • fine aggregate – done above
  • Water – done above

i) Coarse aggregate

  • Aggregates most of which is retained on 4.75mm IS sieve.
  • It can be a stone, gravel or brick aggregate.
  • It shall be hard, dense, durable strong and free from flakes, saturated but dry surface.
  • Course aggregate shall not contain any harmful material such as coal, mica, clay, Shells, organic impurities etc.
  • Can be used graded or of single size as specified

ii) Chemical Admixtures

  • When required, admixtures of approved quality shall be mixed with concrete
  • Admixtures may be any one of the following class:- i) Water Reducing Admixtures, ii) Retarding Admixtures, iii) Accelerating Admixtures.
  • Dosage of these admixtures may vary according to manufacturers specification.
  • Two or more admixtures may not be compatible in the same solution.

10) Concrete Mixing

i) Machine mixing

  • Measured quantity coarse aggregate shall be placed first in hopper, then followed by measured quantities of sand and cement respectively.
  • The dry materials slipped into drum and mixed for atleast four turns
  • While the drum is rotating, water shall be added gradually to achieve water cement ratio as specified.
  • Mixing shall be continued until concrete of uniform colour or uniformly distributed material is obtained (minimum for 2 minutes)

ii) Hand mixing

  • Sand and cement is mixed dry thoroughly on masonry platform or sheet iron tray as in case of mortar.
  • This dry mix of cement and sand is mixed with stone aggregate, this whole mixed dry turning at least 3 times to have uniform mix.
  • 3/4th of the required water shall be added in the hollow made in the middle of the mixed pile and the material is turned towards the middle of pile with spade.
  • Remaining, water shall then be added slowly and gradually, while being mixed to the required quantity.

11) Transportation and handling of concrete

  • Concrete shall be transported from the mixer to the place of laying as rapidly as possible by method will prevent the segregation and loss of any of the ingredients and maintaining the required workability

12) Placing of concrete

  • Concrete shall be as near as possible to its final position.
  • Shall be laid gently (not thrown).
  • Properly vibrated and compacted before setting and should not be disturbed.
  • Maximum free fall of concrete may be taken as 1.5meter to avoid segregation.

13) Curing of concrete

i) Moist curing

  • Exposed surfaces of concrete shall be kept continuously in a damp or wet condition by ponding or by covering with a layer of sacks.
  • kept constantly wet for at least 7 days from the date of placing concrete in case of ordinary Portland cement
  • The period of curing shall not be less than 10 days for concrete exposed to dry and hot weather conditions.
  • In the case of concrete where mineral admixtures or blended cements are used, it is recommended that above minimum periods may be extended to 14 days.
  • Freshly laid concrete shall be protected from rain by suitable covering.

ii) Membrane curing

  • Curing compound may be used
  • Compound is applied as soon as concrete has set.
  • Impermeable membrane such as polythene sheet covering surface may also be used.

14) Measurements of concrete

  • Dimensions of length breadth and thickness shall be measured correct to nearest cm. except for the thickness of slab and partition which shell be measured to nearest 5 mm.

For area near 0.01 sq.m

For volume  0.01 sq.m

  • Shall be measured separately in case:

work in or under water

work in liquid mud

work in or under foul conditions

15) Concrete Tests

  • Slump cone test to check the workability of concrete mix

i) Equipment’s Required for Concrete Slump Test

  • Mould for slump test, non porous base plate, measuring scale, temping rod.
  • The mould for the test is in the form of the frustum of a cone having height 30 cm, bottom diameter 20 cm and top diameter 10 cm. The tamping rod is of steel 16 mm diameter and 60cm long and rounded at one end.

ii) Procedure for concrete slump test

  • Clean the internal surface of the mould and apply oil.
  • Place the mould on a smooth horizontal non- porous base plate.
  • Fill the mould with the prepared concrete mix in 4 equal layers.
  • Tamp each layer with 25 strokes of the rounded end of the tamping rod in a uniform manner over the cross section of the mould. For the subsequent layers, the tamping should penetrate into the underlying layer.
  • Remove the excess concrete and level the surface with a trowel.
  • Raise the mould from the concrete immediately and slowly in vertical direction.
  • Measure the slump as the difference between the height of the mould and that of height point of the specimen being tested.

iii) Results

SPECIFICATION ON CONCRETE

16) Damp proof course

  • This shall consist of cement concrete of specified thickness and proportions.
  • Surface of brickwork or stone masonry work shall be levelled and prepared before laying the cement concrete.
  • Form work is provided along the two sides of wall, to the required height.
  • Edges of DPC should be straight even and vertical
  • Gauge plates are to be provided at 1M interval, connecting the two side planks by nails, keeping at a clear distance equal to the width of wall at plinth level.
  • The concrete mix, shall be placed and compacted well by tamping rods to have thickness of 40 mm.
  • Damp proof course shall not have any joints, the whole concreting be completed without any break.
  • The top surface of concrete, when starts to dry, shall be roughened to provide bondage with the super structure.

17) Curing of damp proof course

  • DPC shall be cured for atleast 7 days, after which it shall be allowed to dry.

18) Measurements damp proof course

  • Length and breadth shall be measured correct to a cm.
  • Area in square meter correct to two places of decimal.
  • Depth should not be less then specified thickness.

Related video

Leave a Reply

Your email address will not be published. Required fields are marked *

error: Content is protected !!