Field testing requirements for TMT reinforcement bars on receipt at site. Covers visual inspection, weight per metre verification, bend tests, tensile tests, and testing frequency as per IS 1786:2008 and IS 1599.
Mandatory Tests on Receipt
Every consignment of rebar must be inspected and tested before acceptance and use
| Test | Method | Acceptance | Frequency |
|---|
| Visual inspection | Manual examination | No surface flaws, cracks, laminations, or excessive rust; ribs clearly visible and uniform | Every lot/consignment |
| Dimensional check — diameter | Vernier caliper at 3 random locations per bar | Within tolerance: ±0.5 mm for bars ≤ 16 mm; ±0.6 mm for bars > 16 mm | 5 bars per lot |
| Weight per metre check | Weigh 1 m length on calibrated scale | Tolerance: ±3% for individual bar; ±2% for average of 5 bars in a lot | 5 bars per lot (min 1 per diameter) |
| Identification marks | Visual — check rolled markings on bar | Manufacturer's logo, grade (Fe 500 / Fe 500D / Fe 550D), and standard marking (IS 1786) must be legible | Every bundle |
| Mill test certificate (MTC) verification | Document review | MTC must show heat number, chemical composition, mechanical properties matching IS 1786 | Every consignment |
Bend & Re-bend Test
Per IS 1599:1985 — Method for Bend Test on Metallic Materials
| Test | Method | Acceptance | Frequency |
|---|
| Bend test | IS 1599 — Bend specimen around mandrel of specified diameter | No crack or fracture visible on the outer surface of the bent portion | 1 per 25 tonnes or part thereof, per diameter |
| Re-bend test | IS 1786 Cl. 10.3 — Bend to 135°, age at 100°C for 30 min, cool, re-bend | No crack or fracture on re-bending; bar must withstand re-bending without breaking | 1 per 25 tonnes or part thereof |
| Mandrel diameter for bend | As per IS 1786 Table 6 | Fe 500: mandrel = 4d; Fe 500D: mandrel = 4d; Fe 550D: mandrel = 5d; Fe 600: mandrel = 5d | — |
Tensile Test Requirements
Per IS 1608 / IS 1786 Cl. 6 — Mechanical properties
| Test | Method | Acceptance | Frequency |
|---|
| Yield strength (0.2% proof stress) | IS 1608 — Tensile testing machine | Fe 500: ≥ 500 MPa; Fe 500D: ≥ 500 MPa; Fe 550D: ≥ 550 MPa; Fe 600: ≥ 600 MPa | 1 per 25 tonnes or part thereof |
| Ultimate tensile strength (UTS) | IS 1608 — Pull to failure | Fe 500: ≥ 545 MPa; Fe 500D: ≥ 565 MPa; Fe 550D: ≥ 600 MPa | 1 per 25 tonnes or part thereof |
| UTS/YS ratio | Calculated from tensile test results | Fe 500: ≥ 1.08; Fe 500D: ≥ 1.08; Fe 550D: ≥ 1.06; Fe 600: ≥ 1.06 | Every tensile test |
| Elongation at fracture | IS 1608 — Measured on gauge length | Fe 500: ≥ 12%; Fe 500D: ≥ 16%; Fe 550D: ≥ 14.5%; Fe 600: ≥ 10% | Every tensile test |
| Total elongation at maximum force (Agt) | IS 1608 — Uniform elongation | Fe 500D: ≥ 5%; Fe 550D: ≥ 5% | Every tensile test |
Frequency of Testing
Sampling and testing frequency as per IS 1786 Cl. 10
| Test | Method | Acceptance | Frequency |
|---|
| Lot definition | IS 1786 Cl. 10.1 | One lot = bars of same diameter, same grade, same heat number, from same manufacturer | Max 25 tonnes per lot |
| Number of samples per lot | Random selection | Minimum 1 tensile test + 1 bend test + 1 re-bend test per lot | 1 per 25 tonnes or part thereof |
| Re-test provision | IS 1786 Cl. 10.4 | If 1 test fails, take 2 additional samples from same lot; both must pass | Double samples from failed lot |
| Retaining samples | Site practice | Retain 2 sample pieces (600 mm each) per lot for dispute resolution | Every accepted lot |
Notes
• Mill test certificates (MTC) are mandatory but do NOT replace site testing — site tests confirm that delivered material matches MTC claims.
• Site bend tests can be done using a simple hand-operated bar bender; tensile tests require a UTM (Universal Testing Machine) and should be done at an approved lab.
• For earthquake-resistant design (IS 13920), only Fe 500D or Fe 550D grades are permitted — standard Fe 500 is not allowed in ductile detailing zones.
• Rejection criteria: any single test failure (after re-test) is grounds for rejecting the entire lot. Do not use partially rejected lots.
• Chemical composition testing (sulphur, phosphorus, carbon equivalent) is typically verified from MTC; site testing is done only in case of dispute.
• BIS licence number and IS 1786 marking on the bar confirm it is a certified product — unlicensed bars must not be used.
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