Procedure for Casting of Concrete Cubes

Procedure for Casting of Concrete Cubes

Procedure for Casting of Concrete Cubes

The following Procedure for Casting of Concrete Cubes detailed given below:

SAMPLE OF CONCRETE

Sample of concrete for test specimen shall be taken at the mixer or in the case of ready mixed concrete from the transportation vehicle at the time of discharge. Such samples shall be obtained by repeatedly passing a scoop or pail through the discharge stream of the concrete. The samples thus obtained shall be mixed on a non-absorbent base with shovel until it is uniform in appearance.

Number of samples to be taken depends on the quantity of concrete. As per IS-456, the following table shall be followed during sampling.

Quantity of concrete in the work (m3) 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 m3 or part thereof.

Note:- Frequency of sampling may be agreed upon internally by supplier and purchaser.

Ebook to Read The Engineer’s Manual of Construction Site Planning

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Procedure for Casting of Concrete Cubes

1.Clean the standard cube moulds 6 Nos thoroughly and tight all nuts-bolts properly.

2.Apply oil to all contract surface of mould.

3.Size of mould is normally from the mixing spot while concreting.

4.Take the random sample from the mixing spot while concreting.

5.Fill the concrete in cubes in 3 layers.

6.Compact each layer with 35 Nos of stroke by tamping rod.

7.Finish the top surface by trowel after completion of last layer.

8.Cover the mould by damp hessian cloth immediately to prevent loss of water.

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9.Each specimen should be taken from various locations of proposed concreting.

10.After 24 hours remove specimen out of mould.

11.While removing,take care to avoid breaking of edges.

12.put coding on cubes by paint or maker,coding should be self explanatory showing site name,concrete location,building number and date of casting.

13.Submerge the specimen in clean fresh water till the time of testing.

14.Test 3 specimens for 7 days and 3 specimens for 28 days curing.

15.Average strength of 3 cubes represents the strength of concrete of particular portion of the structure.

Strength of concrete for various periods

(Table 5.1 – p298 – Properties of Concrete by Adam Neville)

Period Strength
7 days 2/3 of 28 day strength
28 days 1.0
2 months 1.1
3 months 1.16
6 months 1.2
12 months 1.24