ASTM C494/C494M-24 PDF

Full title and description

ASTM C494/C494M-24 — Standard Specification for Chemical Admixtures for Concrete. This specification defines material, performance, test, and qualification requirements for chemical admixtures intended for addition to hydraulic‑cement concrete mixtures, including definitions of admixture types and procedures for laboratory and field evaluation.

Abstract

This standard covers the materials and test methods for chemical admixtures used in hydraulic‑cement concrete. It classifies admixtures by performance (Types A, B, C, D, E, F, G and S), specifies laboratory and field tests (fresh‑concrete properties and hardened properties), and describes procedures for qualification, continued compliance, and lot acceptance including uniformity and equivalence testing. The specification permits SI or inch‑pound units independently and includes safety and chloride‑content cautions relevant to reinforced concrete.

General information

• Status: Active standard (current edition).
• Publication date: June 15, 2024 (designation C494/C494M‑24).
• Publisher: ASTM International.
• ICS / categories: 91.100.30 — Concrete and concrete products.
• Edition / version: C494/C494M‑24 (2024 edition).
• Number of pages: 15 pages.

Scope

Specifies requirements for chemical admixtures to be added to hydraulic‑cement concrete for the purposes indicated by the numbered types: Type A — water‑reducing; Type B — retarding; Type C — accelerating; Type D — water‑reducing and retarding; Type E — water‑reducing and accelerating; Type F — water‑reducing, high‑range; Type G — water‑reducing, high‑range and retarding; and Type S — specific performance admixtures. The scope covers materials, test methods, qualification levels, and limits on use (including recommendations for purchaser verification using the specific cement, aggregates, and mix proportions intended for the project).

Key topics and requirements

• Classification of admixtures by performance type (A, B, C, D, E, F, G, S).
• Three levels of testing and acceptance: Level 1 (initial qualification/provisional acceptance), Level 2 (limited retesting), and Level 3 (lot acceptance/uniformity testing).
• Fresh‑concrete tests required for qualification: slump, air content, time of setting, and water content.
• Hardened‑concrete tests for performance: compressive strength, flexural strength, resistance to freezing and thawing, and length change (shrinkage/expansion) where applicable.
• Uniformity and equivalence procedures (infrared analysis, residue by oven drying, specific gravity determinations) to confirm compositional consistency between supplied admixtures and the qualified product.
• Provisional compliance provisions (allowing early use with follow‑up strength testing and withdrawal if longer‑term performance requirements are not met).
• Dual‑unit system: SI and inch‑pound units are both allowable but treated independently.
• Health, safety, and materials cautions including warning about caustic fresh cementitious mixtures and chloride content considerations for reinforced concrete.

Typical use and users

Used by admixture manufacturers for product specification and qualification; by specifiers and engineers to select and approve admixtures for concrete mixes; by contractors and ready‑mix producers to verify product performance in project mixes; and by independent testing laboratories and owners/purchasers for acceptance testing and lot verification.

Related standards

Commonly referenced ASTM standards and test methods used with C494 include (but are not limited to) ASTM C143/C143M (slump), C231/C231M (air content), C191 (time of setting), C39/C39M (compressive strength of cylinders), C78/C78M (flexural strength), C666/C666M (freeze–thaw resistance), C157/C157M (length change), C150/C150M (Portland cement), C618 (fly ash), C33/C33M (aggregates), and C260/C260M (air‑entraining admixtures). Users should consult the normative references in the standard for the definitive list.

Keywords

chemical admixtures; concrete; water‑reducing; high‑range water reducer; retarder; accelerator; performance admixture; testing; uniformity; equivalence; qualification; ASTM C494; admixture types.

FAQ

Q: What is this standard?

A: ASTM C494/C494M‑24 is the ASTM International specification that defines types, performance requirements, test methods, and qualification procedures for chemical admixtures used in hydraulic‑cement concrete.

Q: What does it cover?

A: It covers classification of admixtures by type, laboratory and field testing protocols (fresh and hardened concrete tests), procedures for initial qualification and continued compliance (three testing levels), and compositional uniformity/equivalence checks.

Q: Who typically uses it?

A: Admixture manufacturers, concrete mix designers, specifiers and consulting engineers, contractors and ready‑mix producers, owners/purchasers, and testing laboratories use the standard for product qualification, acceptance, and specification.

Q: Is it current or superseded?

A: The current edition is designated C494/C494M‑24 (published June 15, 2024). It supersedes prior editions (for example the 2019 edition) and is listed as the active ASTM specification for chemical admixtures.

Q: Is it part of a series?

A: It is part of the family of ASTM concrete and cement standards and is frequently used alongside related test and materials specifications (e.g., standards for cement, supplementary cementitious materials, aggregate specifications, and various concrete test methods).

Q: What are the key keywords?

A: chemical admixtures, concrete, water‑reducing, high‑range, retarding, accelerating, performance testing, uniformity, equivalence, qualification.