ASTM D2850-25 PDF

Full title and description

Standard Test Method for Unconsolidated‑Undrained Triaxial Compression Test on Cohesive Soils — ASTM D2850‑25. This procedure describes preparation, confinement, and strain‑controlled axial loading of cylindrical cohesive soil specimens while preventing drainage, and records total stress–strain behaviour used to determine undrained shear strength under rapid loading conditions.

Abstract

ASTM D2850‑25 specifies an unconsolidated‑undrained triaxial compression test for intact, reconstituted, or remolded cohesive soils. Specimens are placed in a triaxial cell, a confining pressure is applied without permitting drainage, and the specimen is sheared in compression at a constant axial strain rate. Results are reported as total stresses (pore‑pressure effects are not measured) and provide undrained strength and stress–strain relations applicable to rapid loading scenarios.

General information

• Status: Active standard (current edition D2850‑25).
• Publication date: April 9, 2025 (ASTM issuance of D2850‑25).
• Publisher: ASTM International.
• ICS / categories: 93.020 (Earthworks, excavation, foundation construction, underground works).
• Edition / version: D2850‑25 (current revision).
• Number of pages: 7 pages (typical workbook/print length for this test method).

Scope

This test method provides procedures for determining undrained strength properties and stress–strain relations of cohesive soils by measuring total stresses on cylindrical specimens under a confining pressure with no drainage permitted during confinement or shear. It applies to intact, reconstituted, or remolded specimens and is strain controlled; units are presented in SI as the standard. The method does not measure pore‑water pressure (for that see D4767) and is intended for situations where loading is rapid enough that drainage cannot occur.

Key topics and requirements

• Specimen types: intact, reconstituted, or remolded cohesive soils.
• Test environment: triaxial cell with applied confining pressure and no permitted drainage during confinement or shear.
• Loading control: strain‑controlled axial compression at a constant rate of axial deformation.
• Measurements: total axial and confining stresses and axial deformation (pore‑water pressures are not recorded in this method).
• Output: undrained shear strength, stress–strain curves, and Mohr circles based on total stresses (useful for rapid loading cases).
• Units and reporting: SI units are primary; adhere to significant‑figure/rounding guidance in Practice D6026 where applicable.
• Limitations and applicability: results reflect total‑stress behaviour and may not be appropriate where pore‑pressure measurement or drained/partially drained conditions are required.

Typical use and users

Commonly used by geotechnical laboratories, consulting geotechnical engineers, research institutions, university soil mechanics labs, contractors performing site investigation testing, and quality assurance groups. Typical applications include rapid load case design checks, slope‑stability assessments for rapid loading, and comparative laboratory characterisation of cohesive soils where drainage is negligible over the loading period.

Related standards

Closely associated ASTM standards and practices include: Test Method D2166/D2166M (unconfined compressive strength), Test Method D4767 (consolidated, undrained triaxial test with pore‑pressure measurement), Practice D6026 (significant digits and rounding), and Practice D3740 (laboratory competency guidance). D2850 is maintained under ASTM Committee D18 (subcommittee D18.05) and appears in the ASTM soil & rock volume series.

Keywords

unconsolidated‑undrained, triaxial compression, cohesive soils, undrained strength, total stress, confining pressure, strain‑controlled, soil testing, ASTM D2850

FAQ

Q: What is this standard?

A: ASTM D2850‑25 is a standardized laboratory test method that prescribes the unconsolidated‑undrained triaxial compression test for cohesive soils to determine undrained shear strength and stress–strain behaviour under rapid (no‑drainage) loading conditions.

Q: What does it cover?

A: It covers specimen preparation (intact, reconstituted, or remolded), application of confining pressure without drainage, strain‑controlled axial compression, and reporting of total stresses and stress–strain data. It does not include pore‑pressure measurement (see D4767 for that).

Q: Who typically uses it?

A: Geotechnical testing laboratories, consulting engineers, researchers and university labs, and contractors performing site investigations use D2850 for characterising undrained behaviour of cohesive soils under rapid loading scenarios.

Q: Is it current or superseded?

A: The D2850‑25 edition is the current active edition published by ASTM International (issued April 9, 2025). Historical earlier editions (for example D2850‑03AR07 and intermediate revisions) have been superseded by the 2025 revision.

Q: Is it part of a series?

A: Yes — it is part of ASTM’s soil testing suite under Committee D18 (soil and rock) and is commonly referenced alongside related triaxial and compressive strength methods such as D2166/D2166M and D4767. The test method appears in ASTM Vol. 04.08 (Soil and Rock).

Q: What are the key keywords?

A: unconsolidated‑undrained, triaxial, triaxial compression, cohesive soil, undrained shear strength, total stress, confining pressure, strain‑controlled testing.