By
Sourav Dutta
Manager-Civil
Common Hazards/issues normally countered at all construction sites:
Human error in rebar fabrication (manual).
Fig 1 : Incorrect bend
Compromise with safety and quality.
Fig 2 : Safety and Quality issues upon using rebar cutter
Procurement schedule delays affecting site progress, and thereby delaying project completion.
Inventory management. Capital locked in inventory.
Fig 3 : Lack of space at site affects storage/procurement
Rebar pilferage.
Scrap generation and its disposal. Also leading to revenue loss.
Fig 4 : Scrap generation at site
Rebar reconciliation: A challenge to keep wastage within limit.
Space/electric supply availability for bending machine setup.
Fig 5 : Bending machine
Scarcity of skilled masons/labors now-a-days for rebar fabrication. Moreover, their availability during festive season is always an issue.
India continues to use rebar in straight form, other countries have moved to fabricated/Cut & Bend steel.
Advantages of Cut and Bend Steel
- Cost Savings.
- Procurement against exact requirement/orders as per provided Bar bending schedule (BBS).
- Lesser Space required for inventory.
- Timely Delivery and Reliability.
- Reduction in working capital in the project. Improves margin.
- Improved quality and any shape can be accurately fabricated.
- Helps in account reconciliation.
- Direct Usage – practically no space blockage.
- Labor required only for binding / placing / fixing.
- Faster Construction.
- No scrap/offcut generation/pilferage.
Quality improvement on using Cut and Bend Rebar
Slope not exceeding 1 (Horizontal) : 6 (Vertical) as per IS456:2000 in column rebar at splice location
Fig 6 (s) : Column rebars
Fig 7 (s) : Proper mandrel dia used for bending rebar
Fig 8 (s) : Stirrup manufacturing: Wrong & correct practise
A cost comparison for rebar cut & bent at site vs prefabricated rebar is being given for reference:
Cut & bend cost comparison for rebar
Rebar quantity / month = consider average 100 T/month
At site:
| Activity detail | Labour cost (L) | Material cost (M) | Plant cost (P) | Overhead cost (O) | Total Cost (L+M+P+O) | Consideration | ||||||||
| Basic material price | 35000* | 35000 | ||||||||||||
| BBS making charges (staff) | 100 | 100 | 1 jr. staff with salary=Rs 10000 pm | |||||||||||
| Supervision charges (staff) | 180 | 180 | 1 staff with salary=Rs 18000 pm | |||||||||||
| Loading & unloading of rebar from stockyard to fabrication yard | 50 | 50 | ||||||||||||
| Cut & bend labor charges | 2500 | 2500 | Consider cut-bend-tying=Rs4000/T, tying component= Rs 1500/T | |||||||||||
| Cutting machine hire charges | 100 | 100 | Consider hire charge= Rs10000/month | |||||||||||
| Bending machine hire charges | 100 | 100 | ||||||||||||
| Electricity charges | 20 | 20 | ||||||||||||
| Inventory charges | 350 | 350 | 1% of rebar cost for 30 days | |||||||||||
| Lead & lift of rebar from fabrication yard to construction site | 50 | 50 | ||||||||||||
| Scrap @5% material cost | 1750 | 1750 | ||||||||||||
| Collection of scraps and disposal | 25 | 25 | Consider Rs 500/T | |||||||||||
| Savings on selling scrap @ Rs26/Kg | -1300 | -1300 | ||||||||||||
| Total cost per MT at site (Rs) = | 38925 | |||||||||||||
For Cut & Bend (Prefabricated) rebars:
| Activity detail | Labour cost (L) | Material cost (M) | Plant cost (P) | Overhead cost (O) | Total Cost (L+M+P+O) | Consideration |
| Basic material price | 35000* | 35000 | ||||
| Average deviation for Cut & Bend, delivered at construction site | 3000 | 3000 | Varies about Rs 3000-3500/T depending upon certain factors | |||
| Estimated Cut & bend price per MT (Rs) = | 38000 | |||||
Profit of site on using Cut & Bend (%) = (3925-3000)/3925 = 23.6%
*: Indicative basic material price considered for comparison.
We at engineeringcivil.com are thankful to Er. Sourav Dutta for submitting this paper to us. We hope this paper will be helpful for the whole construction industry in general.
If you have a query, you can ask a question here.