IS 1786:2008 · IS 1786 — High Strength Deformed Steel Bars and Wires for Concrete Reinforcement
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.
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.
Also useful
1 related items across IS codes, knowledge articles, design rules, maps and tools