ASTM D7957/D7957M-25 PDF

Full title and description

ASTM D7957/D7957M-25 — Standard Specification for Solid Round Glass Fiber Reinforced Polymer (GFRP) Bars for Concrete Reinforcement. Specifies geometric, material, mechanical and physical property requirements, test methods for qualification and production quality control, and minimum inside bend diameters for bent bars provided in cut lengths and bent shapes for use as concrete reinforcement.

Abstract

This specification covers solid, round glass fiber reinforced polymer (GFRP) bars with an external surface enhancement (for example sand or surface deformation) intended for concrete reinforcement. It defines property limits and required test methods for product qualification and lot acceptance (including mechanical properties such as ultimate tensile force, tensile modulus and ultimate tensile strain; transverse shear and bond strength; and physical properties such as fiber mass content, glass transition temperature and degree of cure). The standard is published as both inch‑pound and SI versions (D7957 and D7957M).

General information

• Status: Active (current edition D7957/D7957M-25).
• Publication date: Published November 15, 2025 (designation year 2025); ASTM record shows an update/last‑updated entry dated January 7, 2026.
• Publisher: ASTM International (Committee D30 / Subcommittee D30.10).
• ICS / categories: 91.100.30 — Concrete and concrete products.
• Edition / version: D7957/D7957M-25 (2025 edition, dual unit designation: inch‑pound and SI).
• Number of pages: 7 pages (core specification); redline/annotated copies may be longer.

Scope

The standard applies to solid, round GFRP bars intended for concrete reinforcement that are produced with an external surface enhancement and supplied in straight or factory‑bent shapes. It sets mandatory geometric, material, mechanical and physical requirements and identifies test methods and acceptance criteria for qualification and production lot testing. Items explicitly excluded include hybrid bars made with more than one load‑bearing fiber type, plain/smooth (no surface enhancement) bars, cross‑sections other than solid round, and pre‑manufactured FRP grids or gratings. The specification is published in both SI and inch‑pound variants and does not address all safety issues associated with use — users must determine applicable safety and regulatory requirements.

Key topics and requirements

• Material definition and permitted geometries: solid, round bars with surface enhancement; factory bent shapes allowed; exclusion of hybrids and smooth bars.
• Qualification and quality‑control tests and acceptance criteria for production lots (tables listing property limits and sampling/testing requirements).
• Mechanical property requirements: ultimate tensile force/strength, tensile modulus of elasticity, and ultimate tensile strain.
• Additional mechanical and durability parameters: transverse shear strength, bond strength to concrete, and durability considerations (moisture and alkaline exposure).
• Physical and manufacturing properties: fiber mass (content), glass transition temperature (Tg), degree of cure, dimensional tolerances and bar marking/traceability.
• Minimum inside bend diameter and rules for bent bars; factory bending requirements and non‑mandatory appendices for standard bend shapes may be included or referenced.

Typical use and users

Used by structural and materials engineers, specifiers, DOTs and infrastructure agencies, manufacturers and quality laboratories, contracting firms and fabricators where corrosion‑resistant reinforcement is required (bridge decks, parking structures, marine structures, and other chloride‑exposed or aggressive environments). The standard is referenced by design codes and acceptance criteria (for example the ACI 440 series and ICC‑ES evaluation criteria) and is used by manufacturers to demonstrate conformance for project submittals and approval lists.

Related standards

Commonly used alongside or referenced by: ACI 440 series design documents (including ACI 440.11), ICC‑ES acceptance criteria for FRP (AC454), ASTM test methods such as ASTM D7205/D7205M (tensile properties of FRP bars) and other bond/tension test methods, and AASHTO guidance for GFRP‑reinforced bridge elements. Designers should check project‑specific code references and local jurisdiction acceptance (for example DOT Approved Product Lists).

Keywords

GFRP, FRP rebar, glass fiber reinforced polymer, concrete reinforcement, non‑metallic rebar, pultruded bars, tensile modulus, bond strength, durability, ACI 440, ICC‑ES AC454.

FAQ

Q: What is this standard?

A: ASTM D7957/D7957M-25 is the ASTM material specification that defines requirements, test methods and acceptance criteria for solid, round glass fiber reinforced polymer (GFRP) bars used as concrete reinforcement. It is published in dual units (inch‑pound and SI).

Q: What does it cover?

A: It covers solid, round GFRP bars supplied in cut lengths and factory‑bent shapes with external surface enhancement, specifying geometric tolerances, mechanical and physical property limits, qualification and lot acceptance test procedures, minimum inside bend diameters, and marking/traceability requirements. It excludes hybrid fiber bars, plain/smooth bars, non‑round cross‑sections and FRP grids.

Q: Who typically uses it?

A: Structural and materials engineers, manufacturers and suppliers of GFRP bars, transportation departments (DOTs), testing laboratories, contractors and spec authors who need to verify that GFRP reinforcement meets recognized manufacturing and quality requirements. It is commonly paired with design guidance such as the ACI 440 series.

Q: Is it current or superseded?

A: The designation D7957/D7957M-25 is the active/current edition (2025 edition); ASTM records indicate the document is active and show an update entry dated January 7, 2026. Previous editions include D7957/D7957M-22. Users should confirm the edition required by their project and check for any subsequent revisions or ballots in progress.

Q: Is it part of a series?

A: It is maintained by ASTM Committee D30 (Subcommittee D30.10) and is part of the family of standards and test methods used for FRP reinforcement and composites; it is commonly referenced together with ASTM tensile and bond test methods and with ACI design standards for FRP‑reinforced concrete.

Q: What are the key keywords?

A: Keywords include: GFRP, FRP rebar, glass fiber reinforced polymer, non‑metallic reinforcement, tensile strength, tensile modulus, bond strength, durability, pultrusion, concrete reinforcement.