Understanding ASTM D2166: The Standard for Unconfined Compression Strength of Cohesive Soil (PDF Overview)
Disclaimer: This post is for informational purposes only. Always refer to the official ASTM standard for complete testing requirements. astm d2166 pdf
Always check the active version. As of this post, the latest designation is ASTM D2166 / D2166M-16 (2023) . The "M" indicates metric units (SI) are now fully integrated. As of this post, the latest designation is
If you are looking for the official , it is available for purchase directly from ASTM International. Below is a breakdown of what the standard covers and why it matters. Below is a breakdown of what the standard
ASTM D2166, officially titled "Standard Test Method for Unconfined Compressive Strength of Cohesive Soil," measures the unconfined compressive strength (qu) of saturated, cohesive soils. This value is then used to estimate the soil's undrained shear strength (Su), typically calculated as Su = qu/2.
ASTM D2166 is a cornerstone of geotechnical lab testing. While the unconfined compression test has limitations, it remains an indispensable tool for preliminary strength assessments. For critical projects, pair it with triaxial or direct shear testing.