Observations:
Following are the observation based on details from Table-1 & Table-2
- Lap length requirement is reducing with higher grade of concrete.
- Lap length requirement is increasing with higher bar diameter.
- Overall impact of overlapping of the reinforcement is 10% to 15% for the
entire project requirement based on the grade of concrete. Therefore, similar
impact on cost of reinforcement steel.
Learning & Recommendations
Following are the recommendation to be implemented for future RCC construction
work.
- Use of higher grade of concrete shall reduce the lap length requirement.
There is 2.7% cost reduction in reinforcement overlapping for M40 grade
of concrete in comparison to the use of M30 grade of concrete (Table-3).
Also, there shall be reduction in concrete quantity & shuttering requirements
in case of higher concrete grade. - Selection of lower bar diameter of the reinforcement for 20mm and above
bars shall reduce the lap length requirement further 2-3%, Further reduction
can be achieved by using require higher grade of concrete.
Conclusion:
Approximately 5% cost reduction in reinforcement requirement can be achieved
with the implementation of the above recommendations. However, the selection
of grade of concrete and bar diameter shall also depend on the quality control
during site execution & use batching plant/ RMC concrete at site.
Table-3
Bar
(mm)Dia (Mt)Qty Length (m)No
LapofM25 M30 M35 M40
Lap
Length(m) (Mt)Wt %
Lap
Length(m) (Mt)Wt %
Lap
Length(m) (Mt)Wt %
Lap
Length(m) (Mt)Wt %8 706 1785999 223250 86709 34.26 4.9 80928 31.97 4.5 71407 28.21 4.0 63891 25.24 3.6
10 1040 1684954 210619 102254 63.12 6.1 95437 58.91 5.7 84209 51.98 5.0 75345 46.51 4.5
12 1198 1347893 168487 98158 87.25 7.3 91615 81.44 6.8 80836 71.85 6.0 72327 64.29 5.4
16 837 529407 66176 51404 81.23 9.7 47977 75.82 9.1 42333 66.90 8.0 37877 59.85 7.2
20 950 384705 48088 46693 115.29 12.1 43580 107.60 11.3 38453 94.95 10.0 34405 84.95 8.9
25 2251 583425 72928 88515 341.49 15.2 82614 318.73 14.2 72895 281.23 12.5 65221 251.63 11.2
32 4074 644595 80574 125178 791.25 19.4 116833 738.50 18.1 103088 651.62 16.0 92237 583.03 14.3
Total 11056 1514 13.7 1413 12.8 1247 11.3 1115 10.1
(lacs)Cost^77391060989873781
Savings in TMT cost w.r.t. M25 Con-crete (Lacs) 71 187 279