: Measures load-induced strains on a specimen that has already undergone wetting-induced swell or collapse. Key Formulas for Feature Development
The test procedure involves:
Apply the predetermined vertical stress required by the project specifications. Allow the specimen to come to equilibrium under this load in its unsaturated state. astm d454621 pdf
| Edition | Key Changes | |---------|-------------| | | Initially titled "Standard Test Methods for One-Dimensional Swell or Settlement Potential of Cohesive Soils" | | 2008 edition | Expanded scope; three alternative methods for measuring free swell, swell pressure, and swell or collapse magnitude | | 2014 edition | Refined procedures for reconstituted and intact specimens | | 2021 edition | Current version (April 2021). Introduces clearer distinction between Methods A, B, and C; updates reference standards and editorial improvements |
| Equipment | Typical Models / Examples | |-----------|--------------------------| | | Fixed-ring or floating-ring models meeting ASTM D4546 and D2435 requirements | | Loading frames | Dead-weight consolidation machines with weight sets (e.g., HM-1100A manual, HM-1120 16 TSF weight set) | | Automated systems | LoadTrac III (for fully automated step-load consolidation/swell testing) | | Soil trimmers | For preparing intact specimens from samples obtained in the field | | Null indicators | For measuring pore pressure without water flow in/out of the specimen | : Measures load-induced strains on a specimen that
This testing standard determines the magnitude of one-dimensional wetting-induced swell or collapse of relatively undisturbed or compacted soils. The "-21" suffix denotes that the standard was last updated or reapproved in the year 2021. It replaced older versions (such as ASTM D4546-14) to improve clarity, precision, and consistency in laboratory reporting. Why Measuring Swell and Collapse Matters
Using the current 2021 edition ensures that laboratory testing complies with modern regulatory frameworks, forensic engineering requirements, and international building codes. 3. The Three Test Methods (A, B, and C) | Edition | Key Changes | |---------|-------------| |
Preventing damage to slab-on-grade foundations from clay expansion.
): The vertical stress required to prevent swelling, or the stress required to return a swollen specimen back to its pre-wetted height. Void Ratio (
: Unlike the first two methods, Method C focuses on what happens after the soil has already swelled or collapsed. It measures how much more the soil will compress when additional structural loads (like a new building) are applied to the already-wetted ground. Key Parameters Measured