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D2217-85 – Standard Test Method Technical Guide
📜 Scope and Significance of Wet Preparation
This standard practice covers the wet preparation of soil samples as received from the field for particle-size analysis and determination of soil constants. Procedure A is used when coarse-grained particles are soft and pulverize readily, or when fine particles are very cohesive and resist removal from coarse particles. Procedure B is essential for soils that never dry out in nature, as drying can alter their characteristics. The liquid limit and plasticity index values from natural moisture samples are typically equal to or higher than from dried samples, especially for fine-grained organic soils where oven drying causes a radical drop in plasticity.
The procedure to be used should be indicated in the specification for the material being tested. If no procedure is specified, the provisions of Procedure B shall govern by default.
| 🟦 Sieve Designation | 📏 Opening Size | 🎯 Function |
|---|---|---|
| No. 10 | 2.00 mm | Wet separation of coarse particles |
| No. 40 | 425 µm | Wet separation of fine particles |
⚠️ Critical Note: Ensure that drying temperatures do not exceed 140°F (60°C) in Procedure A to avoid altering soil properties. Use a thermostatically controlled drying oven for precise temperature regulation.
🛠️ Required Apparatus and Equipment
The apparatus required includes a balance sensitive to 0.1 g for accurate weighing, a mortar and rubber-covered pestle to break up soil aggregations without damaging particles, and sieves conforming to Specification E 11. A riffle sampler or sample splitter is used for quartering samples. Drying apparatus can include a thermostatically controlled oven (capable of maintaining 140°F/60°C and 230°F/110°C), infrared lamps, or air driers. For filtration, Büchner funnels 10 in. (254 mm) in diameter with filter paper or filter candles are specified. Miscellaneous equipment includes pans 12 in. (304.8 mm) in diameter and 3 in. (76.2 mm) in depth, and containers that prevent moisture loss for storage of moist test samples in Procedure B.
| 🟦 Equipment | 📐 Specification | ⚡ Importance |
|---|---|---|
| Balance | Sensitivity to 0.1 g | Precise mass determination |
| Drying Oven | Thermostatically controlled | Maintains safe temperature limits |
| Büchner Funnel | 10 in. (254 mm) diameter | Efficient filtration of fines |
💡 Best Practice: Use filter candles or funnels with appropriate filter paper to enhance retention of fine particles during wet separation, reducing sample loss and improving accuracy.
⚙️ Procedures A and B for Sample Preparation
Procedure A involves drying the field sample at a temperature not exceeding 140°F (60°C), then breaking up aggregates with a mortar and pestle. A wet separation is performed on the No. 10 (2.00 mm) or No. 40 (425 µm) sieve, or both, as needed. The separated fractions are finally dried at a temperature not exceeding 140°F. This method is suitable for soils where coarse particles are soft or fine particles are cohesive.
Procedure B requires that the sample be kept at a moisture content equal to or greater than its natural water content. It is used for soils that may change characteristics upon drying, such as fine-grained organic soils. Samples should be shipped in sealed containers and stored in moisture-proof containers to maintain natural conditions. This procedure is the default if no specific procedure is indicated.
| 🔍 Parameter | 📐 Procedure A | 📐 Procedure B |
|---|---|---|
| Moisture Management | Dried at ≤ 140°F (60°C) | Maintained at natural levels |
| Sieve Usage | No. 10 and/or No. 40 sieves | Wet separation as required |
| Application | Soft coarse particles, cohesive fines | Soils sensitive to drying |
| Default Status | If specified | Governs if not specified |
✅ Key Point: According to the standard, Procedure B is the default when the material specification does not indicate a procedure. This ensures that soils sensitive to drying are properly handled.
❓ Frequently Asked Questions
🔍 Why is Procedure B critical for organic soils? Oven drying can cause a radical drop in plasticity for fine-grained organic soils, so maintaining natural moisture preserves their true characteristics.
💡 What are the temperature limits for drying in Procedure A? The temperature must not exceed 140°F (60°C) to prevent alteration of soil properties.
⚡ Which sieves are specified in this practice? No. 10 (2.00 mm) and No. 40 (425 µm) sieves conforming to Specification E 11 are used.
📌 How should samples be stored for Procedure B? In containers that prevent moisture loss, maintaining moisture content equal to or greater than natural water content.