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D2167-15 – Standard Test Method Technical Guide
📐 Scope and Applicability for In-Place Density Testing
ASTM D2167 – 15, formally the Standard Test Method for Density and Unit Weight of Soil in Place by the Rubber Balloon Method, establishes the procedure for determining the in-place density and unit weight of compacted or firmly bonded soils. This method is widely utilized as a quality control acceptance tool for compacted fill and embankments composed of fine-grained soils or granular soils without appreciable amounts of coarse material.
The standard explicitly limits the material particle size to soils containing no significant amounts of material larger than 37.5 mm (1.5 in.). For soils exceeding this particle size, the standard directs users to alternate methods such as D4914 or D5030. The test is not suitable for organic, saturated, or highly plastic soils that would deform under the pressures applied during the volume measurement phase. Special care is required for unbonded granular soils that cannot maintain stable sides in a small test hole.
Values stated in SI units are regarded as the standard. A critical technical note in Section 1.5.1 clarifies the unit system: while the standard is written using the gravitational system where the pound (lbf) represents a unit of force, the use of scales recording pounds of mass (lbm/ft³) should not be regarded as nonconforming with this test method.
| 🟦 Parameter | 📏 Specification / Value |
|---|---|
| 🎯 Primary Application | Density of compacted or firmly bonded soil in place |
| ⚡ Maximum Particle Size | 37.5 mm (1.5 in.) |
| ❌ Unsuitable Soil Types | Organic, saturated, highly plastic soils (subject to deformation) |
| 📐 Alternate Standards | D4914 or D5030 (for material > 37.5 mm) |
| ⚖️ Unit System Standard | SI units regarded as primary standard |
⚙️ Test Procedure and Volume Measurement Principles
The “Rubber Balloon Method” derives its name from the specialized apparatus used to measure the volume of the excavated test hole. The procedure involves carefully excavating a small, cylindrical hole in the soil layer. All excavated material is collected and weighed to determine the wet mass. The volume of the hole is then determined by placing the rubber balloon apparatus over the hole and filling it with a fluid under controlled pressure, forcing the flexible rubber membrane into the cavity. The volume of fluid required to fill the cavity is precisely measured.
This method requires the soil to be firm enough to withstand the pressure of the balloon without deformation. A representative sample of the excavated material is retained for moisture content determination, allowing the calculation of dry density and dry unit weight. The in-place dry density is then compared to the maximum dry density determined from laboratory compaction tests.
💡 Key Limitation for Granular Soils: Section 1.4 specifically notes that this test method requires special care when applied to (1) soils consisting of unbonded granular materials that will not maintain stable sides in a small hole, (2) soils containing coarse material in excess of 37.5 mm, (3) granular soils having high void ratios, or (4) fill materials containing particles with sharp edges which could puncture the membrane.
📊 Key Measured Properties and Calculation Standards
The primary outputs of this test method are the in-place wet density and dry unit weight of the soil. To assess compaction quality, the resulting in-place dry density is typically expressed as a percentage of the maximum dry density determined from ASTM D698 (Standard Effort, 12,400 ft-lbf/ft³).
The standard requires that all observed and calculated values conform to the guidelines for significant digits and rounding established in Practice D6026. Section 1.6 emphasizes that the procedures used for data collection and calculation are regarded as the industry standard and are representative of the significant digits that should generally be retained, though material variation and user objectives may necessitate adjusted precision.
| 🟦 Referenced Standard | 📐 Purpose | 🎯 Key Data Point |
|---|---|---|
| D653 | Standard Terminology | Definitions for soil, rock, and contained fluids |
| D698 | Lab Compaction Characteristics | Standard Effort: 12,400 ft-lbf/ft³ |
| D6026 | Significant Digits | Rounding and reporting guidelines |
| D4914 / D5030 | Alternate Density Methods | For soil with particles > 37.5 mm |
⚠️ Safety and Compliance Responsibility: As stated in Section 1.7, this standard does not purport to address all safety concerns associated with its use. It is the responsibility of the user to establish appropriate safety, health, and regulatory practices prior to use. Users must also consider that the significant digits used in the standard may not be directly applicable for engineering design analysis without further consideration of material variation.
❓ Frequently Asked Questions
🔍 What is the maximum particle size allowed for this test?
The soil must not contain appreciable amounts of material larger than 37.5 mm (1.5 in.). For materials exceeding this size, the standard recommends using Test Methods D4914 or D5030.
💡 Can this test be used on saturated or organic soils?
No. Section 1.4 explicitly states the test is not suitable for organic, saturated, or highly plastic soils that would deform under the pressures applied during the test. It is intended for compacted or firmly bonded soils.
⚡ How does the standard address the pound (lb) unit system?
Section 1.5.1 clarifies that while the standard is written using the gravitational system where the pound represents force (lbf), the use of balances or scales recording pounds of mass (lbm/ft³) should not be regarded as nonconforming with this test method.
📌 What other ASTM standards are commonly coordinated with D2167?
The standard directly references D653 (Terminology), D698 (Laboratory Compaction Characteristics, Standard Effort of 12,400 ft-lbf/ft³), and D6026 (Significant Digits). The in-place dry density results are typically compared against the maximum dry density established by D698.