ASTM C31/C31M-26 PDF

Full title and description

Standard Practice for Making and Curing Concrete Test Specimens in the Field — ASTM C31/C31M-26. This practice provides standardized procedures for making, transporting, curing, and protecting concrete test specimens (cylinders and beams) taken from fresh concrete in the field and for curing specimens in the laboratory; it distinguishes between standard‑cured and field‑cured specimens and describes uses of each.

Abstract

ASTM C31/C31M-26 specifies field procedures for molding, handling, protecting, transporting, and curing concrete test specimens intended for strength and quality evaluation. The practice supports acceptance testing, mixture proportion verification, quality control, estimation of in-place strength, and assessment of curing effectiveness. It also identifies specimen types (cylinders and beams), applicable exclusions, and unit conventions (SI and inch‑pound).

General information

• Status: Active (current standard).
• Publication date: Approved January 1, 2026; last updated January 15, 2026.
• Publisher: ASTM International.
• ICS / categories: 91.100.30 (Concrete and concrete products).
• Edition / version: C31/C31M-26 (2026).
• Number of pages: 7 pages.

Scope

This practice covers procedures for making and curing cylinder and beam specimens from representative samples of fresh concrete taken during a construction project. It is not intended for concretes without measurable slump, for different specimen sizes/shapes, and is not applicable to lightweight insulating concrete or controlled low strength material (CLSM) without reference to other specific standards; modifications are required for Ultra‑High‑Performance Concrete (UHPC). SI and inch‑pound units are treated as separate standards.

Key topics and requirements

• Procedures for molding and consolidating cylinder and beam specimens in the field.
• Requirements for protecting, marking, and transporting specimens to the laboratory.
• Definitions and distinctions between standard‑cured and field‑cured specimens and their intended uses (acceptance, strength estimation, curing evaluation).
• Instructions for laboratory curing when specimens are standard‑cured and guidance for field curing when required.
• Exclusions and cross‑references to other test methods for special concretes (e.g., C495/C495M for lightweight insulating concrete, D4832 for CLSM, C1856/C1856M for UHPC).
• Unit system policy: SI and inch‑pound values are to be regarded separately; do not mix.
• Safety note: users are reminded to follow appropriate safety and handling practices for fresh cementitious materials.

Typical use and users

Used by construction quality control personnel, concrete testing laboratories, materials engineers, inspectors, contractors, and design engineers to obtain reproducible field specimens for strength testing and to verify curing and concrete quality on construction projects. The standard supports acceptance testing and decision‑making for form/shoring removal, post‑tensioning, and in‑place strength estimation.

Related standards

Commonly referenced ASTM standards include C94/C94M (Ready‑Mixed Concrete Specification), C1064/C1064M (Temperature of Freshly Mixed Concrete), C1077 (Practice for Agencies Testing Concrete), C495/C495M (Lightweight Insulating Concrete), C1856/C1856M (UHPC specimen practice), and D4832 (CLSM specimen procedures). The practice is maintained under ASTM Committee C09, Book of Standards Volume 04.02.

Keywords

concrete; test specimen; specimen molding; specimen curing; field‑cured; standard‑cured; cylinder; beam; compressive strength; transporting specimens; ASTM C31; concrete testing.

FAQ

Q: What is this standard?

A: ASTM C31/C31M-26 is the Standard Practice for Making and Curing Concrete Test Specimens in the Field, specifying procedures for molding, handling, transporting, and curing specimens taken from fresh concrete.

Q: What does it cover?

A: It covers making cylinder and beam specimens in the field, protection and marking, transportation to the laboratory, and requirements for standard and field curing; it specifies exclusions and cross‑references for special concretes and unit conventions.

Q: Who typically uses it?

A: Construction QC staff, testing laboratories, materials and structural engineers, site inspectors, and contractors use it for acceptance testing, quality control, and estimating in‑place concrete strength.

Q: Is it current or superseded?

A: It is current and active as ASTM C31/C31M-26 (approved January 1, 2026; last updated January 15, 2026). The 2026 edition replaces the prior edition (noted as C31/C31M‑25b in publisher records).

Q: Is it part of a series?

A: Yes. C31/C31M is part of ASTM’s concrete testing suite under Committee C09 (Concrete and Concrete Aggregates) and appears in the Annual Book of ASTM Standards, Volume 04.02. It cross‑references related test methods and practices for concrete materials and testing.

Q: What are the key keywords?

A: Concrete, specimen, curing, field‑cured, standard‑cured, cylinder, beam, compressive strength, transporting specimens, ASTM C31.