ASTM D2938
Full Name
ASTM D2938 – Standard Test Method for Unconfined Compressive Strength of Intact Rock Core Specimens
Scope
ASTM D2938 provides a standardized procedure for determining the unconfined compressive strength of cylindrical rock core specimens.
Key points of ASTM D2938:
- Specimen preparation: a rock core sample is first cut to the desired length, typically with a length-to-diameter ratio of 2 to 2.5:1. The ends of the specimen are then machined flat to ensure uniform loading during the test.
- Testing apparatus: the prepared specimen is placed in a loading frame equipped with two steel platens. One platen is spherically seated and lubricated to allow for any irregularities in the specimen’s shape, while the other is a plain rigid platen.
- Application of load: an axial load is applied to the specimen at a controlled and continuous rate until failure occurs. The loading rate is typically specified in the standard and depends on the type of rock being tested.
- Measurement and calculation: during the test, the applied load and the corresponding deformation of the specimen are continuously monitored and recorded. The unconfined compressive strength is calculated as the peak (maximum) load the specimen can withstand divided by its original cross-sectional area.
The unconfined compressive strength determined by this test method is a critical parameter used in various geotechnical and civil engineering design applications, including:
- Foundation design: assessing the strength and stability of rock foundations for bridges, buildings, and other structures.
- Slope stability analysis: evaluating the stability of rock slopes in mining, road construction, and other excavations.
- Tunneling and underground excavations: designing supports and linings for tunnels and underground excavations based on the rock mass strength.
- Rock mass classification: unconfined compressive strength is often used as an input parameter in various rock mass classification systems, such as the Rock Mass Rating and the Q-system.
ASTM D2938 Accredited Laboratory
Applied Testing & Geosciences, LLC is accredited for performing tests using the ASTM D2938 standard. We understand the importance of timely reporting and strive to provide our clients with prompt and efficient services.
Contact us today to discuss your testing needs and receive a quote for our services.
Resources
Keywords
rock; compressive strength; core specimens; loading tests; compression testing; apparatus; instrumentation; procedures; intact; unconfined; determination; standard test method