ASTM C151/C151M-23

Standard Test Method for Autoclave Expansion of Hydraulic Cement

SIGNIFICANCE AND USE
4.1 The autoclave expansion test provides an index of potential delayed expansion caused by the hydration of CaO or MgO, or both, when present in hydraulic cement.3
SCOPE
1.1 This test method covers determination of the expansion of a hardened cement paste when exposed to the autoclave conditions in this method.  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the standard.  
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of regulatory limitations prior to use. For specific precaution statements, see the section on Safety Precautions.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 30-Nov-2023
• ICS: 91.100.10 - Cement. Gypsum. Lime. Mortar
• Technical Committee: C01 - Cement
• Drafting Committee: C01.31 - Volume Change

Relations

• Replaces: ASTM C151/C151M-18 - Standard Test Method for Autoclave Expansion of Hydraulic Cement
• Effective Date: 01-Dec-2023
• Refers: ASTM C219-24 - Standard Terminology Relating to Hydraulic and Other Inorganic Cements
• Effective Date: 01-Apr-2024
• Refers: ASTM C219-20a - Standard Terminology Relating to Hydraulic and Other Inorganic Cements
• Effective Date: 01-Aug-2020
• Referred By: ASTM C266-21 - Standard Test Method for Time of Setting of Hydraulic-Cement Paste by Gillmore Needles
• Effective Date: 01-Dec-2023
• Referred By: ASTM C10/C10M-19 - Standard Specification for Natural Cement
• Effective Date: 01-Dec-2023
• Referred By: ASTM C330/C330M-23 - Standard Specification for Lightweight Aggregates for Structural Concrete
• Effective Date: 01-Dec-2023
• Referred By: ASTM C183/C183M-23 - Standard Practice for Sampling and the Amount of Testing of Hydraulic Cement
• Effective Date: 01-Dec-2023
• Referred By: ASTM D5050-08(2023) - Standard Guide for Commercial Use of Lime Kiln Dusts and Portland Cement Kiln Dusts
• Effective Date: 01-Dec-2023
• Referred By: ASTM C311/C311M-22 - Standard Test Methods for Sampling and Testing Fly Ash or Natural Pozzolans for Use in Portland-Cement Concrete
• Effective Date: 01-Dec-2023
• Referred By: ASTM C1697-21 - Standard Specification for Blended Supplementary Cementitious Materials
• Effective Date: 01-Dec-2023
• Referred By: ASTM C191-21 - Standard Test Methods for Time of Setting of Hydraulic Cement by Vicat Needle
• Effective Date: 01-Dec-2023
• Referred By: ASTM D8378/D8378M-21 - Standard Test Method for Potential Expansion of Steel Slag from Hydration Reactions by Autoclave
• Effective Date: 01-Dec-2023
• Referred By: ASTM C1222-23 - Standard Practice for Evaluation of Laboratories Testing Hydraulic Cement
• Effective Date: 01-Dec-2023
• Referred By: ASTM C331/C331M-23 - Standard Specification for Lightweight Aggregates for Concrete Masonry Units
• Effective Date: 01-Dec-2023
• Referred By: ASTM C1600/C1600M-23 - Standard Specification for Rapid Hardening Hydraulic Cement
• Effective Date: 01-Dec-2023

Overview

ASTM C151/C151M-23 is the internationally recognized standard test method for determining the autoclave expansion of hydraulic cement. Developed by ASTM International, this test method evaluates the potential for delayed expansion in hydraulic cement, which may arise from the hydration of calcium oxide (CaO), magnesium oxide (MgO), or both. The assessment of autoclave expansion is a critical indicator of cement soundness, helping to ensure long-term performance and durability in construction projects.

The standard applies to both SI and inch-pound units, which should be used independently, and provides a referenced, repeatable method essential for materials testing laboratories, cement manufacturers, and construction professionals.

Key Topics

• Autoclave Expansion: The method measures the change in length of hardened hydraulic cement paste specimens after exposure to high-pressure steam conditions in an autoclave. This process accelerates possible long-term expansive reactions, providing rapid evaluation of cement soundness.
• Soundness Assessment: The test identifies potential unsoundness in cement due to excessive expansion, which can compromise structural integrity in concrete and mortar.
• Relevance of CaO and MgO: Hydration of free lime (CaO) or periclase (MgO) in cement can cause delayed expansion. The standard quantifies this behavior to prevent field issues.
• Precision & Repeatability: ASTM C151/C151M-23 specifies detailed procedures for molding samples, autoclaving, and measuring dimensional change, ensuring both intra-laboratory and inter-laboratory consistency.
• Safety Precautions: The standard includes guidelines for safe operation of autoclaves and handling of high-pressure steam, emphasizing operator safety throughout the testing process.
• Unit Consistency: Clear guidance is provided to avoid mixing SI and inch-pound values, maintaining test integrity and regulatory compliance.

Applications

The ASTM C151/C151M-23 test method is foundational for:

• Quality Control in Cement Manufacturing: Cement producers rely on this standard to monitor and control the presence of unsound materials before the product reaches the market.
• Safety Assurance in Construction: Project engineers and contractors utilize autoclave expansion data to select materials with proven durability, reducing risks of future structural damage due to expansion.
• Research & Development: Materials scientists and researchers employ this method to evaluate new types of hydraulic cement and identify optimum formulations with minimal expansion.
• Conformance Testing: Regulatory bodies and independent laboratories use this test method to verify supplier compliance with industry standards for cement soundness.

This method is essential for applications involving reinforced concrete, precast products, shotcrete, and anywhere long-term dimensional stability is critical.

Related Standards

For a comprehensive approach to hydraulic cement testing and terminology, consider these referenced ASTM standards:

• ASTM C187: Test Method for Amount of Water Required for Normal Consistency of Hydraulic Cement Paste
• ASTM C219: Terminology Relating to Hydraulic and Other Inorganic Cements
• ASTM C305: Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
• ASTM C490/C490M: Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste, Mortar, and Concrete
• ASTM C511: Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic Cements and Concretes
• ASTM C856: Practice for Petrographic Examination of Hardened Concrete
• ASTM C1005: Specification for Reference Masses and Devices for Determining Mass and Volume for Use in Physical Testing of Hydraulic Cements
• ASTM C1157/C1157M: Performance Specification for Hydraulic Cement

Practical Value

Implementing ASTM C151/C151M-23 in laboratory practices ensures reliable detection of potential expansion problems before cement is used in critical infrastructure. Its use supports sustainable building by verifying the long-term performance of construction materials and safeguarding structural soundness against material-related failures. Incorporation of this standard in quality assurance programs is a best practice for any organization involved in cement production, testing, or application.

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C151/C151M − 23
Standard Test Method for
Autoclave Expansion of Hydraulic Cement
This standard is issued under the fixed designation C151/C151M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope* Mortar, and Concrete
C511 Specification for Mixing Rooms, Moist Cabinets,
1.1 This test method covers determination of the expansion
Moist Rooms, and Water Storage Tanks Used in the
of a hardened cement paste when exposed to the autoclave
Testing of Hydraulic Cements and Concretes
conditions in this method.
C856 Practice for Petrographic Examination of Hardened
1.2 The values stated in either SI units or inch-pound units
Concrete
are to be regarded separately as standard. The values stated in
C1005 Specification for Reference Masses and Devices for
each system may not be exact equivalents; therefore, each
Determining Mass and Volume for Use in Physical Testing
system shall be used independently of the other. Combining
of Hydraulic Cements
values from the two systems may result in non-conformance
C1157/C1157M Performance Specification for Hydraulic
with the standard.
Cement
1.3 This standard does not purport to address all of the
3. Terminology
safety concerns, if any, associated with its use. It is the
responsibility of the user of this standard to establish appro- 3.1 Definitions:
priate safety, health, and environmental practices and deter- 3.1.1 For definitions pertinent to this test method, see
mine the applicability of regulatory limitations prior to use. Terminology C219.
For specific precaution statements, see the section on Safety
4. Significance and Use
Precautions.
1.4 This international standard was developed in accor- 4.1 The autoclave expansion test provides an index of
dance with internationally recognized principles on standard- potential delayed expansion caused by the hydration of CaO or
ization established in the Decision on Principles for the MgO, or both, when present in hydraulic cement.
Development of International Standards, Guides and Recom-
5. Interferences
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee. 5.1 Pozzolans containing fine-grained quartz have been
reported to cause excessive expansion under autoclave test
2. Referenced Documents
conditions due to alkali-silica reaction that will not occur under
normal service conditions. When excessive expansion of paste
2.1 ASTM Standards:
containing pozzolans occurs, it is recommended that the
C187 Test Method for Amount of Water Required for Nor-
specimens be examined (see Practice C856) for evidence of
mal Consistency of Hydraulic Cement Paste
alkali-silica reaction (Note 1).
C219 Terminology Relating to Hydraulic and Other Inor-
NOTE 1—If the excessive expansion has resulted from alkali-silica
ganic Cements
reaction under autoclave conditions, the pozzolan can be evaluated for
C305 Practice for Mechanical Mixing of Hydraulic Cement
alkali reactivity using the procedure described in Performance Specifica-
Pastes and Mortars of Plastic Consistency
tion C1157/C1157M.
C490/C490M Practice for Use of Apparatus for the Deter-
6. Apparatus
mination of Length Change of Hardened Cement Paste,
6.1 Weighing Devices and Weights, for determining the
mass of materials conforming to the requirements of Specifi-
This test method is under the jurisdiction of ASTM Committee C01 on Cement
cation C1005.
and is the direct responsibility of Subcommittee C01.31 on Volume Change.
Current edition approved Dec. 1, 2023. Published December 2023. Originally
approved in 1940. Last previous edition approved in 2018 as C151/C151M – 18. Gonnerman, H. F., Lerch, W. and Whiteside, T. M., “Investigations of the
DOI: 10.1520/C0151_C0151M-23. Hydration Expansion Characteristics of Portland Cements,” Portland Cement
For referenced ASTM standards, visit the ASTM website, www.astm.org, or Association Research Department Bulletin 45, pp. 1–168, 1953.
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Wang, H., “Autoclave Soundness Test Mischaracterizes Cement-Fly Ash
Standards volume information, refer to the standard’s Document Summary page on Blends by Introducing Alkali-Quartz Reaction,” Cement, Concrete, and Aggregates,
the ASTM website. Vol 24, No. 2, pp. 68–72, 2002.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C151/C151M − 23
6.2 Glass Graduates, 200 mL or 250 mL capacity, and shall be sure the gauge hand has not passed the maximum
conforming to the requirements of Practice C490/C490M. graduation on the scale.
6.3 Molds, conforming to the requirements of Practice 8.2 Test the pressure gauge for proper operation. Always use
C490/C490M for test specimens used in the determination of a thermometer together with the pressure gauge, so as to
length change of cement paste. provide a means of detecting any failure of the pressure gauge
to operate properly, and to indicate any unusual condition.
6.4 Flat Trowel, conforming to the requirements of Test
Method C187. 8.3 Maintain the automatic control in proper working order
at all times.
6.5 Autoclave, consisting of a high-pressure steam vessel
provided with a thermometer well. The autoclave shall be 8.4 Set the safety valve to relieve the pressure at about 6 %
equipped with automatic controls and either a rupture disk with to 10 % above the maximum of 2.1 MPa [305 psi] specified in
a bursting pressure of 2.4 MPa [350 psi] 6 5 % or a safety this test method, that is, at about 2.3 MPa [330 psi]. Unless the
valve that actuates at this pressure. In addition, the autoclave manufacturer has given specific instructions as to maintenance
shall be equipped with a vent valve to allow the escape of air of the safety valve, test the valve twice each year. Test with a
during the early part of the heating period and to release any gauge testing device, or by adjusting the automatic controls to
steam pressure remaining at the end of the cooling period. The allow the autoclave to reach a pressure of about 2.3 MPa
pressure gauge shall have a nominal capacity of 4.0 MPa [330 psi], at which pressure the safety valve will either open or
[600 psi], a dial with a nominal diameter of 115 mm [4 ⁄2 in.] be adjusted to open. Direct the safety valve discharge away
and shall be graduated from 0 MPa to 4.0 MPa [0 psi to from the operator.
600 psi] with scale divisions not exceeding 0.03 MPa [5 psi].
NOTE 2—Unexpected combinations of conditions may occur. For
The error in the gauge shall not exceed 60.02 MPa [63 psi] at
example, in one case the automatic control had failed, the safety valve had
the operating pressure of 2 MPa [295 psi]. The capacity of the
become stuck, and the gauge hand, which at first glance appeared to be at
about zero, had passed the maximum graduation and had come to stop on
heating unit shall be such that with maximum load (water plus
the wrong side of the pin. This condition of the gauge was finally detected
specimens) the pressure of the saturated steam in the autoclave
and the pressure, then of an unknown magnitude, was released before
may be raised to a gauge pressure of 2 MPa [295 psi] in 45 to
failure could occur in the apparatus.
75 min from the time the heat is turned on. The automatic
8.5 Wear heavy leather work gloves to prevent burning of
control shall be capable of maintaining the gauge pressure at
the hands when removing the top of the autoclave at the end of
2 MPa 6 0.07 MPa [295 psi 6 10 psi] for at least 3 h. A gauge
the test. Direct the vent valve away from the operator. When
pressure of 2 MPa 6 0.07 MPa [295 psi 6 10 psi] corresponds
removing the autoclave lid, tilt it so that any steam escaping
to a temperature of 216 °C 6 2 °C [420 °F 6 3 °F]. The
from beneath the lid will be discharged away from the operator.
autoclave shall be designed to permit the gauge pressure to
Care shall be taken to avoid scalding by any liquid that may
drop from 2 MPa to less than 0.07
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: C151/C151M − 18 C151/C151M − 23
Standard Test Method for
Autoclave Expansion of Hydraulic Cement
This standard is issued under the fixed designation C151/C151M; the number immediately following the designation indicates the year
of original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval.
A superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope*
1.1 This test method covers determination of the expansion of a hardened cement paste when exposed to the autoclave conditions
in this method.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety, health, and environmental practices and determine the applicability of
regulatory limitations prior to use. For specific precaution statements, see the section on Safety Precautions.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2.1 ASTM Standards:
C187 Test Method for Amount of Water Required for Normal Consistency of Hydraulic Cement Paste
C219 Terminology Relating to Hydraulic and Other Inorganic Cements
C305 Practice for Mechanical Mixing of Hydraulic Cement Pastes and Mortars of Plastic Consistency
C490/C490M Practice for Use of Apparatus for the Determination of Length Change of Hardened Cement Paste, Mortar, and
Concrete
C511 Specification for Mixing Rooms, Moist Cabinets, Moist Rooms, and Water Storage Tanks Used in the Testing of Hydraulic
Cements and Concretes
C856 Practice for Petrographic Examination of Hardened Concrete
C1005 Specification for Reference Masses and Devices for Determining Mass and Volume for Use in Physical Testing of
Hydraulic Cements
C1157/C1157M Performance Specification for Hydraulic Cement
3. Terminology
3.1 Definitions:
3.1.1 For definitions pertinent to this test method, see Terminology C219.
This test method is under the jurisdiction of ASTM Committee C01 on Cement and is the direct responsibility of Subcommittee C01.31 on Volume Change.
Current edition approved April 1, 2018Dec. 1, 2023. Published April 2018December 2023. Originally approved in 1940. Last previous edition approved in 20162018 as
C151/C151M – 16.C151/C151M – 18. DOI: 10.1520/C0151_C0151M-18.10.1520/C0151_C0151M-23.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C151/C151M − 23
4. Significance and Use
4.1 The autoclave expansion test provides an index of potential delayed expansion caused by the hydration of CaO or MgO, or
both, when present in hydraulic cement.
5. Interferences
5.1 Pozzolans containing fine-grained quartz have been reported to cause excessive expansion under autoclave test conditions due
to alkali-silica reaction that will not occur under normal service conditions. When excessive expansion of paste containing
pozzolans occurs, it is recommended that the specimens be examined (see Practice C856) for evidence of alkali-silica reaction
(Note 1).
NOTE 1—If the excessive expansion has resulted from alkali-silica reaction under autoclave conditions, the pozzolan can be evaluated for alkali reactivity
using the procedure described in Performance Specification C1157/C1157M.
6. Apparatus
6.1 Weighing Devices and Weights, for determining the mass of materials conforming to the requirements of Specification C1005.
6.2 Glass Graduates, 200 or 250-mL200 mL or 250 mL capacity, and conforming to the requirements of Practice C490/C490M.
6.3 Molds, conforming to the requirements of Practice C490/C490M for test specimens used in the determination of length change
of cement paste.
6.4 Flat Trowel, conforming to the requirements of Test Method C187.
6.5 Autoclave, consisting of a high-pressure steam vessel provided with a thermometer well. The autoclave shall be equipped with
automatic controls and either a rupture disk with a bursting pressure of 2.4 MPa [350 psi] 6 5 % or a safety valve that actuates
at this pressure. In addition, the autoclave shall be equipped with a vent valve to allow the escape of air during the early part of
the heating period and to release any steam pressure remaining at the end of the cooling period. The pressure gauge shall have a
nominal capacity of 4.0 MPa [600 psi], a dial with a nominal diameter of 115 mm [4 ⁄2 in.] and shall be graduated from 00 MPa
to 4.0 MPa [0[0 psi to 600 psi] with scale divisions not exceeding 0.03 MPa [5 psi]. The error in the gauge shall not exceed 6
0.02 MPa [6 3 60.02 MPa [63 psi] at the operating pressure of 2 MPa [295 psi]. The capacity of the heating unit shall be such
that with maximum load (water plus specimens) the pressure of the saturated steam in the autoclave may be raised to a gauge
pressure of 2 MPa [295 psi] in 45 to 75 min from the time the heat is turned on. The automatic control shall be capable of
maintaining the gauge pressure at 22 MPa 6 0.07 MPa [295 6 10 psi] [295 psi 6 10 psi] for at least 3 h. A gauge pressure of
22 MPa 6 0.07 MPa [295 6 10 psi] [295 psi 6 10 psi] corresponds to a temperature of 216 6 2°C [420 6 3°F].216 °C 6 2 °C
[420 °F 6 3 °F]. The autoclave shall be designed to permit the gauge pressure to drop from 2 MPa 2 MPa to less than 0.07 MPa
[295 psi to less than 10 psi] 10 psi] in 1 ⁄2 h h after the heat supply has been shut off.
6.5.1 Rupture Disk—The rupture disk shall be made of a material having a tensile strength that is relatively insensitive to
temperature in the range 20 to 216°C [68 to 420°F]20 °C to 216 °C [68 °F to 420 °F] and that is electrochemically compatible with
the pipe leading to it and to its holder.
6.6 Length Comparator—The comparator used for measuring length change of specimens shall conform to the requirements of
Practice C490/C490M.
7. Temperature and Humidity
7.1 Molding Room—Maintain the temperature of the molding room, dry materials and mixing water, and the relative humidity of
the molding room within the limits of Practice C490/C490M.
Gonnerman, H. F., Lerch, W. and Whiteside, T. M., “Investigations of the Hydration Expansion Characteristics of Portland Cements,” Portland Cement Association
Research Department Bulletin 45, pp. 1–168, 1953.
Wang, H., “Autoclave Soundness Test Mischaracterizes Cement-Fly Ash Blends by Introducing Alkali-Quartz Reaction,” Cement, Concrete, and Aggregates, Vol 24, No.
2, pp. 68–72, 2002.
C151/C151M − 23
7.2 Moist Storage Facilities—Maintain the temperature and humidity of the moist storage facilities to the requirements of
Specification C511.
8. Safety Precautions
8.1 The pressure gauge shall have a capacity of 4.0 MPa [600 psi]. A gauge with too small or too large a capacity may be a hazard,
since for pressure above the specified maximum working pressure, with a smaller capacity gauge, the pressure may be off scale,
and with a larger capacity gauge, the arc of movement may be too small to invite attention. The operator shall be sure the gauge
hand has not passed the maximum graduation on the scale.
8.2 Test the pressure gauge for proper operation. Always use a thermometer together with the pressure gauge, so as to provide a
means of detecting any failure of the pressure gauge to operate properly, and to indicate any unusual condition.
8.3 Maintain the automatic control in proper working order at all times.
8.4 Set the safety valve to relieve the pressure at about 66 % to 10 % above the maximum of 2.1 MPa [305 psi] specified in this
test method, that i
...