ASTM C494/C494M-24 is the ASTM International specification for chemical admixtures for concrete, and it sorts them into eight types, A to G and S, by comparing concrete made with each admixture against a reference concrete. A product earns its type by test against Table 1, and one product can hold two types, as dual listings such as A, F on the Caltrans approved list show. EN 934-2:2009+A1:2012 plays the same role in Europe and IS 9103:1999 in India, and all three are product standards for chemical concrete additives.
In C494/C494M-17 and -19e1 Table 1, Types A, D and E must hold mixing water to at most 95 % of the reference and Types F and G to at most 88 %. Only Types A, D, F and G may qualify provisionally, and that status is withdrawn if 6-month strength falls below 100 % of the reference. The flowing-concrete specification ASTM C1017 was withdrawn in 2022 without replacement.
Each value is traced to its source: standards and codes to their issuing body, product values to the data sheet named with them, prices to the dated source beside them (methodology and fact-checking).
The table below sets out the identity of ASTM C494 as ASTM International records it.
| Attribute | Value |
|---|---|
| Issuer | ASTM International, Committee C09, Subcommittee C09.23 Chemical Admixtures |
| Designation and status | ASTM C494/C494M-24, active (ASTM store, updated 2024-08-06); no later edition listed (checked 2026-10-23) |
| First approved | 1962 |
| Types | Eight: A, B, C, D, E, F, G and S (scope 1.1) |
| Test basis | Test concrete against a reference concrete; Levels 1, 2 and 3 of testing |
| Withdrawn sibling | ASTM C1017/C1017M-13e1, flowing concrete, withdrawn 2022 |
| Counterparts | EN 934-2:2009+A1:2012 (Europe); IS 9103:1999 (India) |
What Is ASTM C494?#
ASTM C494 is a product specification, not a test method: it states which admixture types exist, which properties each type must reach relative to a reference concrete, and how the tests are run.
Its full title is "Standard Specification for Chemical Admixtures for Concrete". ASTM Committee C09 holds it through Subcommittee C09.23 Chemical Admixtures, and it sits in Book of Standards Vol. 04.02.
Current edition: ASTM C494/C494M-24#
The current edition is ASTM C494/C494M-24, active, with the ASTM store page updated 2024-08-06 and no later edition listed when checked on 2026-10-23. It supersedes C494/C494M-19e1, which was approved 2019-12-15, published in March 2020 and had its Table 1 editorially corrected in August 2022. The ASTM store abstract of the 2024 edition says "seven types", while scope 1.1 lists eight, Type S included; the scope governs. C494 is the US entry among the concrete admixture standards that a submittal reviewer meets.
What Does ASTM C494 Cover?#
ASTM C494 covers eight types of chemical admixtures, from water reducers and set controllers to high-range water reducers and specific-performance products, each qualified by tests on concrete made with standard cement, aggregates and pozzolan.
Admixtures specified outside ASTM C494#
Five admixture groups have their own ASTM specification or none at all. They are listed below with the document that governs them.
- Air-entraining admixtures: ASTM C260/C260M-24 (active, updated 2025-01-06); see ASTM C260 air-entraining admixtures.
- Chloride-corrosion-inhibiting admixtures: ASTM C1582/C1582M-24 (active, updated 2024-09-24), whose results are not to be used to rank expected field performance; see corrosion-inhibiting admixtures.
- Cold-weather admixture systems: ASTM C1622/C1622M-24, for concrete as low as -5.0 °C (23.0 °F) immediately after placement until initial set; see antifreeze and cold-weather admixtures.
- Pigments: ASTM C979/C979M-24 (active, updated 2024-08-07); see ASTM C979 pigments for integrally colored concrete.
- Shotcrete admixtures: ASTM C1141/C1141M-15 was withdrawn in 2024 without replacement; see shotcrete accelerators.
Supplementary cementitious materials and fibers sit outside C494 for a different reason: they are not admixtures in the ACI sense, and "concrete additive" is this site's umbrella term, not a defined term.
The chloride caveat in Note 3#
Note 3 of ASTM C494/C494M-24 warns that admixtures containing sufficient amounts of chloride may accelerate corrosion of steel reinforcement, and that compliance with C494 does not assure acceptability in reinforced concrete. The building code therefore limits chloride on the concrete, not on the admixture: ACI CODE-318-25 Table 19.3.2.1, as reproduced in NRMCA 2PE004-26, sets 0.15 % water-soluble chloride by mass of cementitious materials for nonprestressed concrete in class C2 and 0.06 % for prestressed concrete. The mechanism behind those limits is explained under chloride ingress and rebar corrosion.
What Are the Eight ASTM C494 Types?#
ASTM C494/C494M-24 names eight types: A water-reducing, B retarding, C accelerating, D water-reducing and retarding, E water-reducing and accelerating, F water-reducing high range, G water-reducing high range and retarding, and S specific performance. A product may carry two types at once: the Caltrans approved list shows dual entries such as A, F.
The table compares the eight types of concrete admixtures in C494 by name, water limit and effect on set, with the water limits as printed in C494/C494M-17 and -19e1 Table 1.
| Type | Name in C494 | Water content limit (C494/C494M-17 and -19e1 Table 1) | Effect on set |
|---|---|---|---|
| A | Water-reducing | At most 95 % of reference | No intended change |
| B | Retarding | No requirement | Delays |
| C | Accelerating | No requirement | Accelerates |
| D | Water-reducing and retarding | At most 95 % of reference | Delays |
| E | Water-reducing and accelerating | At most 95 % of reference | Accelerates |
| F | Water-reducing, high range | At most 88 % of reference | No intended change |
| G | Water-reducing, high range and retarding | At most 88 % of reference | Delays |
| S | Specific performance | No requirement | No intended change; the purchaser states the performance characteristic |
Water-reducing Types A, D and E#
Water reduction is the property that Types A, D and E share: each must hold mixing water to at most 95 % of the reference mix (ASTM C494/C494M-17 and -19e1 Table 1). ACI PRC-212.3-16 uses the same 5 % threshold, describing normal-range water reducers as cutting water by at least 5 %.
Mid-range products have no own letter. NRMCA CIP 15 states that mid-range water reducers have no separate ASTM class and must at least meet Type A, while ACI PRC-212.3-16 places them at 5 to 10 % water reduction without retarding initial set. Their position between the two classes is explained under mid-range water reducers.
Retarding Type B and accelerating Type C#
Type B delays setting and Type C accelerates it, and neither has a water-reduction requirement in C494/C494M-17 and -19e1 Table 1. Table 1 sets their initial and final setting windows against the reference; those time values are not reproduced here because the 2024 table has not been read. EN 934-2:2009+A1:2012 splits acceleration into Table 6 (set accelerating) and Table 7 (hardening accelerating), while C494 has one accelerating Type C.
High-range Types F and G#
A high-range water-reducing admixture reduces mixing water for a given slump by 12 % or more (C494/C494M-19e1 definitions), and Types F and G must hold water to at most 88 % of the reference mix (C494/C494M-17 and -19e1 Table 1). ACI PRC-212.3-16 gives the high-range band as at least 12 to 40 %.
Flowing concrete is specified with these two types: the NRMCA 2026 guide specification calls for HRWR as ASTM C494 Type F or G and does not cite C1017. The letter F has a second meaning in concrete, since Class F in ASTM C618-26 (active since 2026-08-11) is a coal-ash class and has nothing to do with a C494 Type F admixture; the ash class is covered under fly ash in concrete.
Type S: the specific-performance class#
Type S is an admixture that provides a performance characteristic other than reducing water or changing setting time, without adverse effects, such as shrinkage reduction, ASR mitigation or viscosity modification (definition as worded in C494/C494M-19, 3.2.10). Type S is in the scope of C494/C494M-19e1 (1.1.8) and of C494/C494M-24.
The purchaser names the performance characteristic, and the manufacturer substantiates it with data on request (C494/C494M-19e1, 5.4). Type S is not eligible for provisional compliance under C494/C494M-24. A Type S listing limits side effects against Table 1, but it does not test the claimed benefit, so a Type S letter is no proof of shrinkage reduction or ASR control.
The Caltrans approved list carries a calcium nitrite corrosion inhibitor, shrinkage reducers and a viscosity modifier as Type S. Those product groups are described under specialty admixtures (ASTM C494 Type S).
What Does ASTM C494 Table 1 Require?#
Table 1 of ASTM C494 sets each type's limits relative to a reference concrete for water content, time of setting, compressive strength, flexural strength, length change and, for freeze-thaw use, relative durability factor. Only the water limits are stated here, as C494/C494M-17 and -19e1 values; whether the 2024 edition changed any Table 1 value has not been verified, so the other numbers are left to the ASTM text.
The table lists each Table 1 requirement category, what it compares and where its value can be read.
| Requirement | What it compares | Applies to (C494/C494M-17 and -19e1) | Value stated here |
|---|---|---|---|
| Water content, max % of reference | Mixing water at equal slump | A, D, E, F, G | 95 % (A, D, E); 88 % (F, G) |
| Time of setting, initial and final | Deviation from reference, h:min | All eight types | See the ASTM text |
| Compressive strength, min % of reference | 1 day (F, G); 3, 7, 28 days; 6 months; 1 year | All eight types | See the ASTM text |
| Flexural strength, min % of reference | 3, 7 and 28 days | All eight types | See the ASTM text |
| Length change, max | Shrinkage against reference | All eight types | See the ASTM text |
| Relative durability factor, min | Freezing and thawing | Admixtures for air-entrained concrete exposed to freezing and thawing | See the ASTM text |
Water content limits by type#
Types A, D and E must cut water to at most 95 % of the reference mix and Types F and G to at most 88 % (ASTM C494/C494M-17 and -19e1 Table 1). Types B, C and S have no water requirement, and ACI PRC-212.3-16 uses the same 5 % and 12 % thresholds.
A limit of at most 88 % of the reference means at least 12 % less mixing water at the same slump, and EN 934-2:2009+A1:2012 Table 3.1 asks for the same at least 12 % water reduction for a superplasticizer. As a worked example, take a reference mix with 180 kg/m³ (303.4 lb/yd³) of mixing water, an input assumed for illustration: a Type A test mix may use at most 171 kg/m³ (288.2 lb/yd³) and a Type F test mix at most 158.4 kg/m³ (267.0 lb/yd³). That water cut is what lowers the water-cement ratio at constant cement content.
Three levels of testing#
ASTM C494/C494M-24 defines three levels of testing, which the ordered list below sets out.
- Level 1, initial approval: the full Table 1 test series against the reference concrete.
- Level 2, limited retesting: infrared spectrum, residue and relative density, plus water content, time of setting and compressive strength at 3, 7 and 28 days.
- Level 3, lot acceptance or uniformity and equivalence (for example solids, density and infrared spectrum), applied when the purchaser specifies it.
Provisional compliance and the six-month check#
Only Types A, D, F and G may qualify provisionally under ASTM C494/C494M-24, when setting, length change and durability factor meet Table 1 and the alternative strength values in parentheses are met. Provisional status is withdrawn if 6-month strength is below 100 % of the reference.
The parenthesized alternative strengths come from a statistical analysis of 103 C494 evaluation tests and correspond to a 99 % probability of passing the later-age strength requirements (C494/C494M-19e1). The editions differ on timing: the 19e1 wording allowed the check at six months or one year, while the 2024 wording uses six months.
Which Tests and Reference Materials Does ASTM C494 Use?#
ASTM C494 judges an admixture with eight measurements on fresh and hardened concrete, each run by an ASTM test method the specification cites. The measurements are slump, air content, time of setting, water content, compressive strength, flexural strength, length change and resistance to freezing and thawing (ASTM C494/C494M-24).
The table lists the test methods named in the C494/C494M-19e1 referenced documents with their current editions on the ASTM store.
| Property | ASTM method cited by C494 | Current edition | Page |
|---|---|---|---|
| Slump | C143 | C143/C143M-26b | concrete slump test |
| Air content | C231 or C173 | C231/C231M-26; C173/C173M-26 | air content tests |
| Time of setting | C403 | C403/C403M-23 | setting time of concrete |
| Compressive strength | C39 | Edition not stated | None |
| Flexural strength | C78 | Edition not stated | None |
| Length change | C157 | C157/C157M-24e1 | drying shrinkage |
| Freezing and thawing | C666 | Edition not stated | freeze-thaw damage |
| Reference air-entraining admixture | C233 | C233/C233M-24 | None |
Reference concrete and batches#
The reference concrete and the test concrete are made from Type I or Type II cement, pozzolan, fine and coarse aggregate and an air-entraining admixture, with at least three batches per test condition (ASTM C494/C494M-24). C494 cites ASTM C233 for the reference air-entraining admixture, and C233/C233M-24 is the active edition. C494/C494M-24 also carries the caveat that fresh hydraulic cementitious mixtures are caustic and may cause chemical burns.
Uniformity and equivalence checks#
Uniformity and equivalence are the Level 3 checks for lot acceptance, using the infrared spectrum, the residue (solids) and the relative density. They apply when the purchaser specifies them (ASTM C494/C494M-24). The tolerances sit in Section 6 of the ASTM text; they are not reproduced here because they were read only in an earlier edition.
How ASTM C494 Types Map to the European and Indian Specifications#
Each ASTM C494 type has a counterpart table in EN 934-2:2009+A1:2012 and a counterpart type in IS 9103:1999, but a counterpart is not an equivalent. Each has its own reference concrete and limits, so a C494 report does not prove an EN 934-2 or IS 9103 claim. EN 934-2 also caps the admixture at not more than 5 % by mass of the cement content (EN 934-2:2009+A1:2012, 3.2.1), and its reference concrete is set in EN 480-1:2023.
The table maps each C494 type to its EN 934-2 table and IS 9103 type, with the thresholds that are verified.
| C494 type | EN 934-2:2009+A1:2012 table | IS 9103:1999 type | Verified threshold | Page |
|---|---|---|---|---|
| A | Table 2 (water reducing/plasticizing) | Water-reducing | C494: at most 95 % water (C494/C494M-17 and -19e1); EN Table 2: water reduction at least 5 %, strength at least 110 % at 7 and 28 days | EN 934-2 admixture requirements |
| B | Table 8 (set retarding) | Retarding | EN Table 8: initial set at least control + 90 min, final at most control + 360 min | IS 9103 concrete admixtures specification |
| C | Table 6 (set accelerating) and Table 7 (hardening accelerating) | Accelerating | EN Table 6: initial set at 20 °C at least 30 min, at 5 °C at most 60 % of control; EN Table 7: at 20 °C and 24 h at least 120 % of control strength | None |
| D | Table 10 (set retarding/water reducing/plasticizing) | Retarding | C494: at most 95 % water; EN Table 10: 28-day strength at least 100 % with Table 8 setting | None |
| E | None of Tables 2 to 13 combines water reduction and acceleration | Accelerating | C494: at most 95 % water | None |
| F | Tables 3.1 and 3.2 (superplasticizing) | Superplasticizing | C494: at most 88 % water; EN Table 3.1: water reduction at least 12 %, at least 140 % at 1 day | None |
| G | Tables 11.1 and 11.2 (set retarding/superplasticizing), values not reproduced: not in the public preview | Superplasticizing, retarding type | C494: at most 88 % water | None |
| S | No single class; Table 9 (water resisting) and Table 13 (viscosity modifying) cover two functions | Not among the five IS types | Purchaser-stated characteristic | None |
| All (ACI) | ACI PRC-212.3-16 water-reduction bands: normal at least 5 %, mid-range 5 to 10 %, high-range at least 12 to 40 % | n/a | AASHTO M 194 listed with C494 in ACI PRC-212.3-16 Table 1.2 | ACI 212.3R-16 report on chemical admixtures; plasticizer vs superplasticizer |
Air entrainers stay outside the map: C260/C260M-24 in the US and EN 934-2 Table 5 in Europe.
Which Admixture Pages Does ASTM C494 Govern?#
ASTM C494 governs every chemical admixture family on this site except air entrainers, and the type a product declares decides which page explains its dosage and effects. The table pairs each type with its admixture page.
| C494 type | Admixture page | What that page adds |
|---|---|---|
| A | water-reducing admixtures | Normal and mid-range products, dosage and effects |
| B and D | set-retarding admixtures; hydration-control admixtures | Retarder chemistry, hot weather and long hauls; dual B and D claims |
| C and E | accelerating admixtures; non-chloride accelerators; calcium chloride in concrete | Chloride and non-chloride Type C products and dose limits |
| F and G | superplasticizers (high-range water reducers) | Polymer types, dosage and slump life |
| S | shrinkage-reducing admixtures; viscosity-modifying admixtures (VMA); integral waterproofing admixtures | Type S members; integral waterproofing is Type S only where the product claims it |
| C, plus ASTM C1582 | calcium nitrite corrosion inhibitor | Calcium nitrite products are Type C accelerators; a Type B or D retarder is needed for neutral set |
| Not C494 | air-entraining admixtures | ASTM C260/C260M-24 |
How to Read an Admixture Data Sheet Against ASTM C494#
An admixture data sheet supports an ASTM C494 claim when it names the type or two types, the edition and a Level 1 test report against Table 1. For reinforced work, the chloride content belongs on the same sheet.
The six checks below turn a data sheet into a verifiable C494 claim.
- Find the type letter, or two letters such as A and F.
- Check the edition: C494/C494M-24 is current; -19e1 and older are superseded.
- Ask for the test report and whether compliance is provisional (Types A, D, F and G only).
- Read a Type S claim for the stated performance characteristic.
- Read the chloride content against Note 3 for reinforced concrete.
- Check every standard listed beside C494: the Plastol 6400 data sheet lists ASTM C494 Type A and F, ASTM C1017 Type I, AASHTO M194 and NSF/ANSI 61, and its C1017 claim refers to a withdrawn standard.
A C494 type, an EN 934-2 declaration of performance and an IS 9103 type are three separate claims, each proven by its own test against its own reference concrete. Comparing those claims across bids is the core of sourcing from concrete admixture manufacturers and suppliers.
State DOT approved-product lists#
State DOT lists record the C494 type that each product holds for highway work. The Caltrans approved materials list gives each product its C494 type (single or dual, such as A, F), composition class, approval expiration and Build America, Buy America information under 2 CFR 184.3 (last edit 2026-10-22).
The Illinois DOT list dated 2026-10-09 gives each water reducer and HRWR with its AASHTO NTPEP report number and flags provisional entries. One chemistry can sit under different types: calcium nitrite products are C494 Type C accelerators, yet Caltrans lists a calcium nitrite corrosion inhibitor as Type S.
Writing ASTM C494 into a project specification#
A project specification names the C494 type generically, without brands. NRMCA's 2026 guide specification (2PE004-26, March 2026, 2.14) assigns Type A to water reducers, Type F or G to high-range water reducers, Type C or E to accelerators, Type B or D to retarders and Type S to workability-retaining and other special products. It advises avoiding brand names and using generic wording such as "Water reducers conforming to ASTM C494 Type A".
The same guide advises against chloride limits on admixtures and asks for chloride limits on the concrete, consistent with ACI 318 and ACI 301 exposure classes; chloride-based admixtures are avoided only in prestressed or reinforced concrete. Dual claims exist: MasterSet DELVO and GCP RECOVER both state compliance with ASTM C494 Type B and Type D. FHWA TechBrief HIF-18-017 calls Type E "set-retarding and water-reducing" in one paragraph, while its own classification list gives the C494 meaning, water-reducing and accelerating.
How Has ASTM C494 Changed Since 1962?#
ASTM C494 was first approved in 1962, and the current edition is C494/C494M-24, active with the ASTM store page updated 2024-08-06. The ASTM edition history lists 19 versions from C494-99a to C494/C494M-24, as the table shows.
| Year | Event | Source |
|---|---|---|
| 1962 | C494 originally approved | C494/C494M-19e1 front matter |
| 1999 to 2019 | Editions 99a, 99a-e1, 04, 05, 05a, 08, 08a, 10, 10a, 11, 12, 13, 15, 15a, 16, 17, 19 and 19e1 | ASTM edition history |
| 2019 | C494/C494M-19e1 approved 2019-12-15, published March 2020; Type S in scope 1.1.8 | C494/C494M-19e1 front matter |
| 2022 | 19e1 Table 1 editorially corrected (August); ASTM C1017/C1017M-13e1 withdrawn | ASTM store |
| 2024 | C494/C494M-24 published (store page updated 2024-08-06); ASTM C1141/C1141M-15 withdrawn | ASTM store; ASTM C09.46 |
| 2026 | C494/C494M-24 still active, no later edition listed (checked 2026-10-23) | ASTM store |
ASTM C1017: the withdrawn plasticizing-admixture specification#
ASTM C1017/C1017M-13e1, "Standard Specification for Chemical Admixtures for Use in Producing Flowing Concrete", was withdrawn in 2022 without replacement (ASTM store, page updated 2022-01-14). It defined Type I plasticizing and Type II plasticizing and retarding admixtures, with requirements for time of setting, slump increase, compressive and flexural strength, length change and relative durability factor, uniformity by infrared, residue and specific gravity, and three levels of testing.
US practice now specifies flowing concrete through C494: the NRMCA 2026 guide specification calls for HRWR as ASTM C494 Type F or G and does not cite C1017. A search for "flowable concrete" returns flowable fill (CLSM) pages, which describe a different material from flowing concrete. Flowing concrete itself is made with superplasticizers (high-range water reducers).
Where Is the Official ASTM C494 Text?#
The official ASTM C494 text is published by ASTM International on its store as C494/C494M-24, 15 pages, listed at USD 80.00 on 2026-10-23. The document carries DOI 10.1520/C0494_C0494M-24 and ICS 91.100.30, and the ASTM store record is the only source this page links for the text.
Where ASTM C494 Sits Among Admixture Documents#
ASTM C494 is the US specification in a wider set of admixture documents: ACI Concrete Terminology defines the chemical admixture, ACI PRC-212.3-16 reports on 12 admixture groups, and AASHTO M 194 is listed beside C494. ACI CT-25 defines a chemical admixture as "a liquid, or dispersible powder, used as an ingredient in a cementitious mixture to improve its economy and/or properties in the plastic and/or hardened state". Three neighbor documents are listed below.
- ACI PRC-212.3-16 (formerly 212.3R-16), 2016, 76 pages: water-reduction bands of at least 5 % (normal range), 5 to 10 % (mid-range) and at least 12 to 40 % (high range).
- ASTM C94/C94M-26c (active, updated 2026-08-12), the ready-mixed concrete specification; see admixtures in ready-mix concrete.
- ACI CT-25 and ASTM C125/C125M-26b (active, updated 2026-06-29) definitions, which separate admixtures from SCMs and fibers; see admixture vs additive.
ASTM C494 FAQs#
What does Type A mean in ASTM C494?#
Type A is the ASTM C494 class for a water-reducing admixture, which must cut mixing water to at most 95 % of the reference mix (C494/C494M-17 and -19e1 Table 1).
What does Type G mean in ASTM C494?#
Type G is a high-range water-reducing and retarding admixture: like Type F, it must cut water to at most 88 % of the reference mix (C494/C494M-17 and -19e1 Table 1). It also delays setting.
Is there a code for admixture in concrete?#
Yes: chemical admixtures are specified by ASTM C494/C494M-24 in the US, EN 934-2:2009+A1:2012 in Europe and IS 9103:1999 in India.
Is ASTM C494 the same as AASHTO M 194?#
No: AASHTO M 194 is a separate document that ACI PRC-212.3-16 Table 1.2 lists beside ASTM C494 for the same admixture types. Its current edition is not reproduced here because it has not been verified.
Which ASTM C494 type is best?#
The right ASTM C494 type is the one the project specification names, proven by a test report against Table 1.