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D6473 – Standard Test Method Technical Guide
📐 Scope and Definitions
This test method covers the determination of specific gravity and absorption of rock for erosion control. The specific gravity may be expressed as bulk specific gravity or apparent specific gravity. Bulk specific gravity and absorption are based on a 24 ± 4‑h soaking time for the rock specimens tested. This test is appropriate for breakwater stone, armor stone, riprap, and gabion sized rock materials, or similar.
The use of reclaimed concrete and other materials is beyond the scope of this test method. All observed and calculated values shall conform to the guidelines for significant digits and rounding established in Practice D6026, unless superseded by this standard.
| 🟦 Parameter | 📏 Specification |
|---|---|
| Test Scope | Specific gravity (bulk or apparent) and absorption of rock for erosion control |
| Soaking Time | 24 ± 4 hours |
| Specimen Materials | Breakwater stone, armor stone, riprap, gabion sized rock |
| Unit Systems | SI or inch‑pound (use independently) |
| Significant Digits | Conform to Practice D6026 |
⚙️ Test Procedure and Unit Considerations
The test procedure involves soaking the rock specimens for the specified duration to determine their specific gravity and absorption. The specific gravity can be expressed as bulk or apparent, depending on the required calculation. It is critical to follow the specified soaking time to ensure consistent results.
Unit considerations: The standard requires that values be stated in either SI units or inch‑pound units, and these systems shall not be combined. When using inch‑pound units, the gravitational system is implied, where the pound represents force. However, recording pounds of mass (lbm) from balances is acceptable.
⚠️ Important: To avoid nonconformance, ensure that SI and inch‑pound units are not mixed. Always use one system independently for all measurements and calculations.
📊 Key Measured Properties
Bulk specific gravity and absorption are essential for evaluating rock quality in erosion control applications. These properties influence the weight and porosity of materials, affecting their performance in structures like breakwaters and riprap revetments. The absorption value is particularly important as it indicates the rock’s susceptibility to weathering and freeze‑thaw cycles.
For accurate results, adhere to the rounding guidelines from Practice D6026. The significant digits retained should be appropriate for the intended use, though this standard does not specify exact limits for engineering design.
💡 Tip: When conducting tests, maintain the soaking time precisely within the 24 ± 4‑hour window to ensure reproducibility of bulk specific gravity and absorption values.
❓ Frequently Asked Questions
🔍 What is the purpose of ASTM D6473/D6473M‑24?
This standard provides a test method to determine the specific gravity and absorption of rock used for erosion control, such as in breakwater stone, armor stone, riprap, and gabion materials.
💡 How long should the rock specimens be soaked?
Rock specimens should be soaked for a duration of 24 ± 4 hours to determine bulk specific gravity and absorption.
⚡ What are the unit requirements for this test?
Values must be reported in either SI or inch‑pound units, and the two systems should not be combined. The inch‑pound system in this standard uses the gravitational system, but recording mass in pounds (lbm) is acceptable.
📌 Is reclaimed concrete within the scope?
No, the use of reclaimed concrete and other non‑natural materials is beyond the scope of this test method.