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D5093-15 – Standard Test Method Technical Guide
The ASTM D5093-15 standard provides a standardized procedure for field measurement of infiltration rate using a double-ring infiltrometer with a sealed inner ring. This test method targets low-permeability soils with infiltration rates ranging from 1×10⁻⁵ cm/s to 1×10⁻⁸ cm/s. It is applicable to natural soil deposits, recompacted soil layers, and amended soils such as soil-bentonite and soil-lime mixtures. The method adheres to the significant digit guidelines in Practice D6026.
📖 Scope and Applicability
This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock (Subcommittee D18.04). It is intended for in-place soils and provides a direct measurement of infiltration rate. The method is not suitable for measuring hydraulic conductivity, as additional boundary condition information is required. All calculated values must conform to Practice D6026 for rounding and significant digits.
The following table outlines the applicable test methods based on infiltration rate:
| 🟦 Infiltration Rate Range (cm/s) | 📏 Designated Test Method |
|---|---|
| 1×10⁻⁵ to 1×10⁻⁸ | D5093 (Sealed Inner Ring) |
| ≥1×10⁻⁵ | D3385 (Standard Double-Ring) |
⚙️ Test Procedure and Equipment
The equipment consists of a double-ring infiltrometer with a sealed inner ring. The rings are inserted into the soil, and water is ponded in both rings. The sealed inner ring minimizes lateral flow and ensures accurate measurement of vertical infiltration. The infiltration rate I is calculated from the volume of water added to the inner ring over time, expressed in m/s.
💡 Tip: Proper installation is crucial. Ensure good contact between the sealed inner ring and the soil to prevent bypass flow. The test is typically conducted until a constant rate is achieved.
📊 Key Measured Properties and Limitations
The primary measured quantity is the infiltration rate (I), defined as the volume of water entering the soil per unit area per unit time. This test does not provide hydraulic conductivity values. Understanding this distinction is critical for data interpretation.
| 🟦 Term | 📖 Definition (per D5093) |
|---|---|
| Infiltration | Downward entry of liquid into a porous body. |
| Infiltration Rate (I) | Quantity of liquid entering per unit area per unit time (m/s). |
| Infiltrometer | Device to pond liquid and measure entry rate. |
⚠️ Warning: The units of infiltration rate and hydraulic conductivity are similar (m/s), but they are not equivalent. Infiltration rate depends on the hydraulic gradient and other boundary conditions. Do not directly equate these parameters without additional data.
❓ Frequently Asked Questions
🔍 What is the range of infiltration rates measured by this method?
The test method covers infiltration rates from 1×10⁻⁵ cm/s to 1×10⁻⁸ cm/s. For rates equal to or greater than 1×10⁻⁵ cm/s, Test Method D3385 is recommended.
💡 How does D5093 differ from D3385?
D5093 uses a sealed inner ring to prevent boundary flow, making it suitable for low-permeability soils. D3385 is a standard double-ring infiltrometer for higher infiltration rates. The sealed inner ring in D5093 allows for measurements in very low permeability materials.
⚡ Why is a sealed inner ring important?
The sealed inner ring minimizes water flow along the ring-soil interface, ensuring that the measured rate reflects true soil permeability. This is essential for accurate testing in fine-grained or amended soils.
📌 Can this method be used for all soils?
No, it is specifically for natural soil deposits, recompacted soil layers, and amended soils like soil-bentonite or soil-lime mixtures. For highly permeable soils, use D3385. Refer to the scope for detailed applicability.