BID Document for Guest House with Boundary Wall.pdf - Integrated ...

9.1 Frequency of sampling:
9.1.1 Sampling Procedure – A random sampling procedure shall be adopted to ensure that each concrete batch
shall have a reasonable chance of being tested i.e. the sampling should be spread over the entire period of
concreting and cover all mixing units.
9.1.2 Frequency – The minimum frequency of sampling of concrete of each grade shall be in accordance with the
following;
Quantity of Concrete in the Work, m 3
Number of Samples
1-5 1
6-15 2
16-30 3
31-50 4
51 and above 4 plus one additional sample for each additional 50 m 3 or
part thereof
9.1.3 Test Specimen- Three test specimens shall be made from each sample for testing at 28 days Additional cubes
may be required for various purposes such as to determine the strength of concrete at 7 days or at the time of
striking the form work or to determine the duration of curing , or to check the testing error. Additional cubes
may also be required for testing cubes cured by accelerated methods as described in IS: 9013-1978. The
specimen shall be tested as described in IS: 516-1959.
9.2 Test Strength of Sample:
The test strength of the sample shall be the average of the strength of three specimens. The individual
variation should not be more than ±15 percent of the average.
Concrete shall be handled from the place of mixing to the place of final deposit as rapidly as practicable by
methods which will prevent the segregation or loss of the ingredients .It shall be deposited as nearly as
practicable in the final position to avoid re-handling of flowing. Unless specially permitted by the Engineer-
In-Charge, concrete shall not be dropped freely from a height of more than 2 meters.
Before placing the concrete, the moulds shall be cleaned of shavings, pieces of wood or other rubbish. When
placing the concrete the finer materials must be carefully worked against the moulds so that the faces of
concrete shall be left perfectly smooth and free from honeycombing upon withdrawal of the moulds. Any
defect in this respect must be dealt with by the contractor as directed by the Engineer-in-charge without any
extra charges therefore.
Depositing concrete under water shall not be allowed without specific permission form the Engineer-incharge.
The method of concreting to be adopted in such cases shall have to be previously approved by him.
During placing and also immediately after deposition, the concrete shall be thoroughly compacted by
ramming, spearing etc. until it has been made to penetrate and fill all the spaces between and around the steel
rods, around embedded fixtures, and into the corners of formwork in such a manner as to ensure a solid mass
entirely free from voids. If so directed by the Engineer-in-charge, in addition to usual ramming, spearing etc.
sufficient number and suitable type of vibrators may have to be used on important jobs to enable working with
a comparatively low water-cement ratio and ensure the maximum possible degree of compaction and
homogeneity. It is imperative that the work should be done quickly as well as efficiently and adequate number
of hands must therefore be employed to ensure this.
Concrete shall be placed and compacted in its final position before setting has commenced and shall not
subsequently be disturbed.
Concreting shall be carried out continuously up to construction joints the position and arrangement of which
shall be predetermined by the Engineer-in-charge or his representative. Any rest, pauses, such as for meal,
shall also be subject to his approval. All concreting work should be so programmed as not to necessitate work
at night. if for any reasons this becomes imperative, the contractor shall obtain previous permission of the
Engineer-in-charge or his representative and made proper lighting arrangements to his satisfaction.
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