ISO 6934-4-2020 PDF

Full title and description

Steel for the prestressing of concrete — Part 4: Strand. Specifies technical and delivery requirements for high‑strength steel strand for use in prestressed concrete; applies to strand that has been given a stress‑relieving heat treatment in accordance with the general requirements of ISO 6934‑1 and covers common strand constructions (2, 3, 7 and 19 wires) and a range of grades for prestressing applications.

Abstract

ISO 6934‑4:2020 defines requirements for manufactured prestressing strand (including dimensions, construction, mechanical properties, permissible welds/joints, lay/pitch ranges, testing, marking and packaging). The document covers ten grades of strand intended for prestressed concrete and takes precedence over ISO 6934‑1 where there is a direct conflict.

General information

• Status: Published / current international standard.
• Publication date: 30 November 2020 (publication: Nov 2020).
• Publisher: International Organization for Standardization (ISO).
• ICS / categories: 77.140.15 (Steels for reinforcement of concrete); 91.080.40 (Concrete structures).
• Edition / version: Edition 2 (2020).
• Number of pages: 9 pages (English edition / main text length as published).

Information verified against the ISO catalogue entry and national standards bodies' listings.

Scope

Applies to stress‑relieved steel strand manufactured and supplied for prestressed concrete applications. The standard covers strand constructions containing 2, 3, 7 or 19 individual wires and specifies requirements for ten strand grades, including dimensional tolerances, mass per unit length, characteristic tensile forces, lay/pitch limits, restrictions on welds/joints, tests to demonstrate conformity and requirements for marking and packaging. Where ISO 6934‑1 (general requirements) and ISO 6934‑4 differ, the requirements of ISO 6934‑4 prevail.

Key topics and requirements

• Defined strand constructions: 2‑wire, 3‑wire, 7‑wire (including compacted 7‑wire) and 19‑wire patterns with specified lay/pitch ranges.
• Ten standardized grades of strand covering a range of characteristic tensile forces and nominal strengths for prestressing uses.
• Requirements for stress‑relieving heat treatment (reference to ISO 6934‑1) and for continuous manufacture and rewinding into reels.
• Dimensional and mass‑per‑length tables and tolerances, plus characteristic tensile force values for each strand size/grade.
• Restrictions and permissible practice for welds/joints (e.g., prohibition of welds in certain strand types unless agreed and limited butt‑weld frequency for others).
• Manufacturing, finishing, appearance, protection against mechanical damage and requirements for compacted strand.
• Testing and inspection requirements (tensile tests, elongation/extension, verification of characteristic forces, sampling methods and acceptance criteria).
• Marking, traceability and packaging/delivery conditions to ensure preservation and correct identification on site.

Summary of principal technical requirements derived from the standard's clauses and commercial previews.

Typical use and users

Used by manufacturers of prestressing strand, precast‑concrete and post‑tensioning suppliers, structural and geotechnical engineers specifying prestressed elements, procurement/specification teams, testing and certification bodies, and construction contractors who handle, store and install prestressing materials. The standard is intended to ensure consistent product performance and interchangeability in design and construction of prestressed concrete works.

Related standards

Key related documents include ISO 6934‑1 (Steel for the prestressing of concrete — Part 1: General requirements), other parts of the ISO 6934 series covering wires and bars (parts 2, 3 and 5 and related revisions), and specialty standards such as ISO 14655 (epoxy‑coated strand). Users should consult the ISO/TC 17/SC 16 work programme for the full list of related parts and any subsequent revisions.

Keywords

prestressing strand, strand, prestressing steel, stress‑relieved strand, 7‑wire, compacted strand, characteristic tensile force, lay/pitch, ISO 6934, prestressed concrete.

FAQ

Q: What is this standard?

A: ISO 6934‑4:2020 is the International Standard that specifies requirements for steel strand used to prestress concrete (strand given a stress‑relieving heat treatment). It is Part 4 of the ISO 6934 series.

Q: What does it cover?

A: It covers strand constructions (2, 3, 7 and 19 wires), ten grades of strand, dimensional/tolerance tables, mechanical characteristics (characteristic tensile forces), limits on welds/joints, manufacturing and finishing requirements, testing and inspection, and marking/packaging requirements for delivery.

Q: Who typically uses it?

A: Strand manufacturers, prestressing suppliers, structural engineers, specifications and procurement teams, test laboratories and contractors involved in production, supply and installation of prestressed concrete elements.

Q: Is it current or superseded?

A: ISO 6934‑4:2020 (Edition 2, published November 2020) is the current published edition replacing the 1991 edition; it is listed as the active ISO document for Part 4 as of its 2020 publication. Standards are subject to periodic review by ISO (typically every 5 years).

Q: Is it part of a series?

A: Yes — it is Part 4 of the ISO 6934 series (Steel for the prestressing of concrete). Other parts address cold‑drawn wire, quenched and tempered wire, hot‑rolled bars and general requirements (e.g., ISO 6934‑1, ISO 6934‑2, ISO 6934‑3, ISO 6934‑5). Consult ISO/TC 17/SC 16 listings for the series and revisions.

Q: What are the key keywords?

A: prestressing strand; strand construction; 7‑wire; compacted strand; stress‑relieved; characteristic tensile force; prestressed concrete; ISO 6934.