ASTM C151/C151M-23 PDF

Full title and description

ASTM C151/C151M-23 — Standard Test Method for Autoclave Expansion of Hydraulic Cement. This method describes the preparation, autoclave exposure, and measurement of length change of hardened cement paste specimens to provide an index of potential delayed expansion caused by hydration of free lime (CaO), periclase (MgO), or similar expansive constituents in hydraulic cements.

Abstract

This test method provides a standardized procedure to expose hardened cement paste (or appropriate mortar specimens where specified) to high-temperature, high-pressure autoclave conditions and to measure resulting dimensional change. The measured autoclave expansion is used as an indicator of potential soundness problems due to free CaO or MgO and as a comparative index for quality control and research. Values are reported in either SI or inch‑pound units (each system to be used independently). The standard includes requirements for specimen preparation, apparatus (including a comparator and autoclave), exposure cycle, measurement, and reporting.

General information

• Status: Active.
• Publication date: Current edition approved December 1, 2023; published December 2023.
• Publisher: ASTM International.
• ICS / categories: 91.100.10 — Cement. Gypsum. Lime. Mortar.
• Edition / version: C151/C151M-23 (2023 edition).
• Number of pages: 4 pages.

Scope

This test method covers determination of the expansion of a hardened cement paste specimen when exposed to the autoclave conditions specified in the method. It is intended to provide an index of potential delayed expansion resulting from hydration of free lime or magnesia in hydraulic cements. The standard does not address all possible safety concerns; users must establish appropriate safety, health, and environmental practices before use. SI and inch‑pound unit systems are provided and must be used independently when applied.

Key topics and requirements

• Purpose: Measure autoclave expansion of hardened cement paste as an index of potential soundness problems (free CaO/MgO hydration).
• Specimen preparation: Standardized molds and mixing practice for paste (or specified mortar), curing and demolding per the method.
• Apparatus: Autoclave with pressure control and safety devices, length comparator for measuring specimen dimensional change, and calibrated weighing devices as required.
• Autoclave exposure conditions: Typical autoclave cycle corresponds to a saturated-steam gauge pressure of about 295 psi (≈2.0 MPa) at roughly 216 °C, maintained for the specified duration (commonly 3 hours in established practice); the autoclave must be capable of reaching and holding the required pressure/temperature and of controlled depressurization. Exact exposure parameters and timing are specified in the body of the method.
• Units and reporting: Results reported in the selected unit system (SI or inch‑pound) and recorded as length change (expansion) with required specimen identification and test conditions.
• Safety and calibration: Follow standard safety precautions for high-pressure steam apparatus; comparator and pressure instruments must be calibrated and meet the specification limits in the method.

Typical use and users

Used by cement manufacturers, quality control laboratories, testing laboratories, materials researchers, specification writers, and construction materials engineers to screen cements for potential soundness (expansive) issues, to compare cement lots, and to support research into cement chemistry and durability. The method is also referenced in test programs and by standards bodies for related soundness and expansion assessments.

Related standards

ASTM C151/C151M references and is used alongside related ASTM standards and practices such as C187 (normal consistency), C305 (mechanical mixing), C490 (use of apparatus for determination of length change), and C1005 (weights and weighing devices), among others referenced in the method and supporting documents. These related documents cover specimen preparation, apparatus practices, and measurement methods that complement C151/C151M testing requirements.

Keywords

autoclave expansion; hydraulic cement; soundness; free lime; periclase; CaO; MgO; length change; comparator; autoclave test; cement quality control.

FAQ

Q: What is this standard?

A: ASTM C151/C151M-23 is the standardized test method for determining autoclave expansion of hydraulic cement (hardened paste specimens) to indicate potential delayed expansion from free CaO or MgO in the cement.

Q: What does it cover?

A: It covers specimen preparation, required apparatus (including autoclave and comparator), autoclave exposure cycle and conditions, measurement of length change, reporting, and related safety and calibration considerations. SI and inch‑pound unit systems are provided and must be used independently.

Q: Who typically uses it?

A: Cement producers, independent testing and quality control laboratories, researchers in cement and concrete technology, and specification authors use this standard to screen and compare cement soundness characteristics.

Q: Is it current or superseded?

A: It is current. The C151/C151M-23 edition was approved December 1, 2023 and published in December 2023 (current active edition as of that date).

Q: Is it part of a series?

A: It is part of ASTM Committee C01 activities on cement and is published in the Annual Book of ASTM Standards (Volume 04.01). It is typically used in conjunction with related test methods and practices in the C01 family (for example, C187, C305, C490, and C1005).

Q: What are the key keywords?

A: Autoclave expansion, hydraulic cement, soundness, free lime (CaO), periclase (MgO), length change, autoclave, comparator, cement quality control.