ISO 6935-2:2019

Overview

ISO 6935-2:2019 - Steel for the reinforcement of concrete - Part 2: Ribbed bars specifies technical requirements for ribbed reinforcing bars (rebar) used in concrete. It applies to steel supplied as bars, coils and de‑coiled products, and covers both weldable and non‑weldable steels. The standard excludes ribbed bars made from finished products (for example plates or railway rails) and leaves production processes to the manufacturer’s discretion. The 2019 edition also introduces provisions for hot‑rolled threaded reinforcing bars.

Key topics and technical requirements

ISO 6935-2:2019 provides comprehensive criteria to ensure consistent quality and performance of rebar used in concrete structures. Major subjects include:

• Dimensions, mass per unit length and permissible deviations - nominal diameters, cross‑sectional areas and mass tolerances are defined (see the standard’s tables).
• Rib geometry and requirements - number and distribution of transverse ribs, rib height, spacing, flank inclination and relative rib area to ensure bond with concrete.
• Chemical composition - cast and product analysis requirements to control alloying elements and trace chemistry affecting weldability and mechanical behaviour.
• Mechanical properties - tensile properties (strength, yield, elongation), bending and rebending after ageing, and fatigue performance.
• Testing methods - procedures for tensile tests, bend/rebend tests, fatigue tests and chemical analysis, referencing ISO 15630‑1 and other normative documents.
• Designation, marking and identification - bar marking, bundle identification and examples of marking systems to support traceability.
• Conformity and acceptance - factory production control, evaluation of characteristic values, sampling and acceptance testing for deliveries.
• Annexes - informative examples of marking systems and options for agreements between manufacturer and purchaser.

Practical applications and who uses this standard

ISO 6935-2:2019 is essential for stakeholders who specify, produce, test or use steel reinforcement:

• Steel producers and rebar manufacturers - to design and certify ribbed bar products that meet international acceptance criteria.
• Structural and civil engineers - to select suitable reinforcement with known mechanical and bond characteristics for concrete design.
• Construction contractors and fabricators - for procurement, quality control and on‑site verification of rebar deliveries.
• Testing laboratories and inspection bodies - to perform standardized tensile, bend, fatigue and chemical tests.
• Regulators and procurement teams - to define contract specifications and ensure conformity assessment for safety and interchangeability.

Adopting ISO 6935-2 helps ensure reliable concrete reinforcement, improved rebar bond performance, and consistent material traceability across international projects.

Related standards

• ISO 15630‑1 (test methods for reinforcing bars, rods and wire)
• ISO 14284 (sampling and preparation for chemical analysis)
• ISO/TR 9769 (methods of analysis for steel and iron)
• Other parts of the ISO 6935 series for plain and other reinforcing steel types

Keywords: ISO 6935-2:2019, ribbed bars, rebar, reinforcement steel, concrete reinforcement, mechanical properties, chemical composition, testing, marking, conformity.