All about civil construction knowledge- PARAM VISIONS

What should be the weight & number of reinforcement steel bars in a bundle./ Tolerance or rolling margin for the steel bundle as per IS-1786.


 1. Why the steel bars of different diameters are bundled having a different number of bars in each bundle?




The steel bars are carried from the seller's destination to the purchaser's construction site by truck, tractor, or any such transporting vehicle. The bundled steel bars help to ease the loading & unloading work in a lesser time. The weight of the bar bundle is kept nearer to 50kg. so that two persons can lift them easily, by holding on to each end of the bundle.

The steel bars are manufactured having a standard length of 12m. for all types of bars, having different diameters. The weight of an individual bar having different diameters varies for a given length of 12m. The larger the dia. of a bar, the more the weight will be. 

So, in order to keep the bundle wt. nearer to 50kg., the only way that can be achieved is by keeping the different number of bars in a bundle, according to the bar diameter.


2. What is the number of TMT bars in each bundle, having different diameters?

The different diameter bars with the number of bars in each bundle and the weight of a single bundle are given in the table below.



Bar dia.

in mm.

Bar/

bundle

in nos.

Bar

 wt.

in

kg/m.

Std.

 length

in m.

Bundle

 wt.

in kgs.

8

10

0.395

12

47.40

10

7

0.617

12

51.83

12

5

0.89

12

53.40

16

3

1.58

12

56.88

20

2

2.47

12

59.28

25

1

3.85

12

46.20

32

1

6.31

12

75.72

 

3. What is the tolerance or roller margin for the steel bars as per IS-1786(2008)?

The rolling margin for the different dia. bars is specified in IS-1786, and I have calculated the purchase range by weight for each diameter bar. If the weight of the steel bundle goes above or below the given range, then you should discard such bundles.

Given below is the table, having bundle weight and the permissible purchase range by weight for different diameter bar

Bar dia.

in mm.

Bundle wt.

in kgs.

Tolerance

IS-1786

in % by wt.

Purchase

Range

in kgs.

8

47.40

±7

44.08 - 50.72

10

51.83

±7

48.21 - 55.46

12

53.40

±5

50.73 - 56.07

16

56.88

±5

54.03 - 59.72

20

59.28

±3

57.50 - 61.05

25

46.20

±3

44.81 -47.59

32

75.72

±3

73.44 - 78.00

 

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