IS 10790 (Part 2) : 2000Methods of sampling of steel for prestressed and reinforced concrete, Part 2: Reinforcing steel

IS 10790 Part 2:2000 is the method of sampling of reinforcing steel for reinforced concrete — how a *representative* sample of reinforcement bars is drawn from a consignment so the IS 1786 strength/ductility acceptance (IS 1608 tensile, IS 1599 bend/re-bend) actually describes the lot. It is the reinforcing-steel companion to Part 1 (prestressing steel).

It sits in the reinforcement stack:

• IS 1786 — HSD reinforcing bars (the product being accepted) · IS 456 — RCC design
• IS 1608 Part 1 — tensile test · IS 1599 — bend/re-bend · IS 10790 Part 1 — sampling of prestressing steel

Reinforcement steel varies by cast, size and source, and bar substitution/sub-grade supply is a real risk on site. The acceptance only protects the structure if the sample is representative:

• Lot definition (size/grade/cast/source), number and points of bars sampled per lot size — across the consignment, not a few convenient bars
• Specimens for yield/0.2% proof stress, UTS, elongation (IS 1608) and bend/re-bend ductility (IS 1599) — *both* strength and ductility, judged vs IS 1786 for the grade
• Chain: sample (this) → test → judge vs IS 1786 → accept/reject the lot

The engineering point: rebar acceptance disputes (low yield, failed bend, wrong grade, under-section/under-mass) very often unwind not to the mill but to the sample — a few convenient bars, an undefined lot. Reinforcement is the tension capacity of every RCC member; a non-representative sample certifies the bars you happened to grab, not the steel going into the structure.

Scenario: an HSD bar consignment for RCC.

Step 1 — define lots: group by size/grade/cast/source; split the consignment into lots per IS 10790 Part 2.

Step 2 — sample representatively: the standard number of bars from across the lot — not a convenient bundle.

Step 3 — test: tensile (yield/UTS/elongation, IS 1608) and bend/re-bend (IS 1599) — strength *and* ductility; also check mass-per-metre/section.

Step 4 — judge the lot: against IS 1786 for the grade; accept/reject the lot on the valid result.

Step 5 — control thereafter: keep sampling by consignment — a later sub-grade delivery is invisible without it.

Representative sampling makes the IS 1786 acceptance meaningful; a convenience sample certifies the grabbed bars, not the reinforcement in the structure.

1. Convenience sampling. A few grabbed bars don't represent the lot — the acceptance certifies nothing.

2. No lot definition. Mixed casts/sizes treated as one 'lot' breaks the statistics.

3. Testing only strength. Acceptance is strength and bend/re-bend ductility (IS 1599) — both per IS 1786.

4. One-time sampling. Later sub-grade/under-mass deliveries slip in without per-consignment sampling.

5. Confusing it with Part 1. Part 2 = reinforcing steel; Part 1 = prestressing steel (higher criticality).

• IS 1786 — HSD reinforcing bars (acceptance benchmark) · IS 456 — RCC design
• IS 1608 Part 1 — tensile test · IS 1599 — bend/re-bend (ductility)
• IS 10790 Part 1 — sampling of prestressing steel · IS 2502 — bending & fixing of bars

IS 10790 Part 2 is reaffirmed and underpins reinforcement acceptance — and reinforcement is the tension capacity of every RCC member, with sub-grade supply, under-mass bars and wrong-grade deliveries being real, recurring site risks. As with all sampling standards the lesson is blunt: a IS 1786 acceptance only protects the structure if the sample genuinely represents the lot, and disputed low-yield / failed-bend / under-section results very often unwind to the *sample* (a convenient bundle, an undefined lot), not the mill. Define lots, sample across the consignment, test strength and bend/re-bend ductility together, judge the lot, and keep sampling per consignment so a later sub-grade delivery can't slip in. Don't confuse it with the higher-criticality Part 1 for prestressing steel — but apply the same discipline: witness the sampling, or 'representative' means 'whatever was easy to reach'.