ASTM C157/C157M is a standard test method for determining length change in hardened hydraulic-cement mortar and concrete specimens made in the laboratory and exposed to controlled temperature and moisture conditions. It is used when a lab needs comparative dimensional-stability data tied to shrinkage or expansion behavior, not just strength results.
In practice, ASTM C157/C157M usually leads to a length-comparator workflow with controlled conditioning and repeat readings over time. If you need help deciding whether this method fits your mixture, specimen program, or reporting requirement, Contact Us.
ASTM C157/C157M Standard Test Method for Length Change of Hardened Hydraulic-Cement Mortar and Concrete
ASTM C157/C157M focuses on linear length change in hardened hydraulic-cement mortar and concrete specimens. The method is used to evaluate expansion or contraction caused by factors other than externally applied force and temperature change while specimens are kept under defined laboratory conditions.
Because the result depends on specimen preparation, curing, storage, and reading practice, this standard is usually part of a broader dimensional-stability program rather than a stand-alone equipment purchase. Labs normally pair it with the cited ASTM edition, suitable comparator apparatus, and controlled conditioning space.
Quick Definition
ASTM C157/C157M is an ASTM test method used for comparative evaluation of length change in hardened hydraulic-cement mortar and concrete.
| Topic | ASTM C157/C157M at a Glance |
|---|---|
| Document type | Standard test method |
| What it measures | Length change associated with expansion or contraction of hardened mortar or concrete under controlled conditions |
| Specimen focus | Laboratory-made hardened hydraulic-cement mortar and concrete specimens |
| Common equipment path | Length comparator, reference accessories, specimen preparation tools, and controlled curing or conditioning equipment |
What This Standard Covers
This standard covers determination of length change in hardened hydraulic-cement mortar and concrete specimens made in the laboratory and exposed to controlled temperature and moisture conditions.
It addresses dimensional change from causes other than applied force and temperature change. The method can also support experimental or product evaluations that use nonstandard mixing, placing, handling, or curing conditions, provided those departures are reported clearly with the results.
Why This Standard Matters in Testing
Length-change data is useful when teams compare mixtures, screen formulation changes, or study whether a cementitious material shows problematic expansion or contraction under controlled laboratory exposure.
For QA/QC and R&D programs, ASTM C157/C157M helps connect mixture design, curing practice, and dimensional stability into one repeatable workflow. It is a practical method when a project needs comparative change-over-time data rather than a single mechanical property result.
Common Materials, Product Types, or Applications Covered
Common materials include hydraulic-cement mortars and concretes prepared as laboratory specimens. The method is relevant to conventional mixtures as well as comparative studies involving different cementitious ingredients, admixtures, or mixture proportions.
ASTM C157/C157M is often used in mixture development, dimensional-stability comparison, and laboratory qualification work where hardened cementitious materials need to be compared under controlled conditions.
Common Test or Verification Workflow
The usual workflow starts with specimen preparation and an initial comparator reading at the required stage of the method. Specimens are then stored or exposed under controlled conditions and remeasured over time so that length change can be tracked and reported.
- Prepare or condition specimens to the cited ASTM procedure.
- Establish the initial comparator reading.
- Maintain the required curing, storage, or exposure environment.
- Take repeat length measurements at the specified intervals.
- Calculate and report length change, including any nonstandard handling or conditioning.
That reporting discipline matters because results can shift when mixing, curing, demolding, or storage conditions change from the standard path.
Equipment Commonly Used for This Standard
ASTM C157/C157M usually points to a measurement system centered on a length comparator and the accessories needed to obtain repeatable reference and specimen readings.
- Length comparator apparatus for hardened mortar and concrete measurements
- Reference bar and related comparator accessories
- Specimen molds or specimen-preparation tools appropriate to the program
- Curing, moist storage, water storage, or environmental conditioning equipment matched to the procedure
- General concrete laboratory tools for mixing, casting, demolding, and handling
For many labs, apparatus selection is tied closely to ASTM C490/C490M, while specimen preparation and conditioning can also involve ASTM C341/C341M. The most important quoting point is not just the comparator itself, but the full measurement and conditioning setup around it.
How to Read This Designation or Revision
The designation identifies the ASTM document and its edition year. In a citation such as ASTM C157/C157M-24e1, the year shows the edition year, and the epsilon suffix indicates an editorial change made without creating a new year designation.
This standard presents SI and inch-pound values as separate standard systems, so one unit system should be used consistently within a test setup and report. Edition control matters because apparatus references, specimen conditioning, and reporting expectations can change from one revision to another.
Related Standards, Methods, or Frameworks
Several ASTM documents are commonly associated with ASTM C157/C157M in dimensional-stability testing programs.
- ASTM C490/C490M: covers the apparatus and procedures used for length-change measurements of hardened cement paste, mortar, and concrete.
- ASTM C341/C341M: covers preparation and conditioning of cast, drilled, or sawed hydraulic-cement mortar and concrete specimens used for length-change measurements.
- ASTM C1698: is relevant when the project specifically needs autogenous strain data at early ages rather than hardened length-change data alone.
If the job is focused on apparatus selection, specimen preparation, or early-age strain behavior, those related documents can materially affect the right equipment scope.
Get the Right ASTM C157/C157M Equipment Path
If you are selecting a length comparator system, specimen accessories, or conditioning equipment for ASTM C157/C157M work, we can help scope a practical setup for your lab. Request a Quote.
