Physical Address
304 North Cardinal St.
Dorchester Center, MA 02124
D2168-10 – Standard Test Method Technical Guide
📐 Scope and Application (D2168-10)
ASTM D2168-10 covers the essential practices for calibrating mechanical devices used in the laboratory compaction of soils and soil-aggregates. It is strictly applicable for equipment used in conjunction with standards such as Test Methods D698 and D1557, and Practice D6026. The core principle, as specified in Section 1.2, involves adjusting the weight of the mechanical rammer so that the mechanical compactor produces compaction results equivalent to manual compaction methods.
⚠️ Important Note on Calibration Scope: Calibration for use with one practice (e.g., D698) does not automatically qualify the mechanical equipment for use with another testing practice (e.g., D1557). A distinct calibration must be performed for each specific testing protocol as stated in Section 1.1.
⚙️ Calibration Practices Overview
The standard distinguishes between two alternative calibration procedures. A mechanical compactor meeting the requirements of Practice A or Practice B is not required to fulfill the conditions of the alternate practice.
| 📋 Feature | 🟦 Practice A (Section 5) | 🟧 Practice B (Section 6) |
|---|---|---|
| Basis of Calibration | Compaction of a selected soil sample | Deformation of a standard lead cylinder |
| Method Focus | Simulates actual soil compaction results | Provides a physical deformation check |
| Cross-Qualification | Conformance to either Practice A or B is sufficient; the other is not required per Section 1.4. | |
💡 Tip for Practitioners: When selecting between Practices A and B, consider your specific quality control requirements. The lead cylinder method (Practice B) offers a fast, repeatable physical standard, while the soil sample method (Practice A) provides a direct correlation to the specific material being compacted in the field or lab.
📏 Referenced Documents and Unit Standards
The standard operates under the inch-pound unit system, as noted in Section 1.5, with metric values provided for reference only. It integrates heavily with foundational ASTM geotechnical standards. The following table lists key documents referenced within D2168-10.
| 📏 Standard Designation | 🎯 Title / Purpose |
|---|---|
| D653 | Terminology Relating to Soil, Rock, and Contained Fluids |
| D698 / D1557 | Test Methods for Laboratory Compaction Characteristics of Soil (Standard / Modified Effort) |
| D2487 | Practice for Classification of Soils for Engineering Purposes (Unified Soil Classification System) |
| D6026 | Practice for Using Significant Digits in Geotechnical Data |
| E11 | Specification for Woven Wire Test Sieve Cloth and Test Sieves |
| E145 | Specification for Gravity-Convection and Forced-Ventilation Ovens |
❓ Frequently Asked Questions
🔍 What is the specific purpose of calibrating a mechanical compactor per D2168-10?
The purpose, as described in Sections 1.1 and 1.2, is to check and adjust the mechanical device so it yields identical results to manual compaction methods by specifically adjusting the weight of the mechanical rammer.
💡 How do Practice A and Practice B differ fundamentally?
Practice A (Section 5) relies on the compaction behavior of a selected soil sample to verify the rammer setting. Practice B (Section 6) relies on the physical deformation of a standard lead cylinder. As per Section 1.4, a compactor calibrated to one practice does not need to meet the requirements of the other.
⚡ Why does the standard include a discussion about units in Section 1.5.1?
The standard acknowledges that it is common practice in engineering to use “pounds” to represent both mass (lbm) and force (lbf). To avoid confusion, ASTM D2168-10 has been written using the gravitational system of units (lbf for force/weight) for the inch-pound system, while noting that using balances recording lbm for density is acceptable and not a nonconformance.
📌 What other ASTM standards directly interact with D2168-10?
D2168 is designed to support the calibration of mechanical rammers used specifically in Test Methods D698 (Standard Proctor) and D1557 (Modified Proctor). It also incorporates terminology from D653, soil classification from D2487, and significant digit rules from D6026.