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D6140-22 – Standard Test Method Technical Guide
📐 Terminology and Specimen Conditioning
According to ASTM D6140‑22, asphalt retention is defined as the volume of asphalt cement retained by paving fabrics per unit area after submersion. The test requires specimens to be conditioned in a controlled atmosphere. The standard atmosphere for testing geotextiles is specified in Terminology D4439 and D123, with air maintained at a relative humidity of 50 to 70 % and a temperature of 21 ± 2 °C (70 ± 4 °F).
| 🟦 Condition | 📏 Requirement |
|---|---|
| 🌡️ Temperature | 21 ± 2 °C (70 ± 4 °F) |
| 💧 Relative Humidity | 50 to 70 % |
💡 Proper conditioning is critical for accurate results. Ensure specimens are exposed to the standard atmosphere for at least 24 h before testing.
⚙️ Test Procedure and Asphalt Grade
The test method involves weighing each specimen, submerging it in asphalt cement maintained at a specified temperature, and then draining it in an oven at the same temperature for a specified period. The asphalt cement grade should be PG 64‑22 as per Specification D3381/D3381M unless otherwise agreed upon. After draining, the specimens are weighed to determine the asphalt retention volume.
| 📐 Step | 🎯 Details |
|---|---|
| Specimen Preparation | Weigh individual conditioned specimens |
| Asphalt Cement | Grade PG 64‑22 (or equivalent) |
| Submersion | At specified temperature in asphalt cement |
| Drainage | Hang in oven at same temperature for specified time |
| Final Weighing | Weigh specimens after drainage |
⚠️ Results may vary depending on the type of asphalt cement used. Always specify the grade when reporting asphalt retention values.
📊 Significance of Asphalt Retention
This test method provides an index value for asphalt retention in full‑width paving fabrics used in interlayer systems. It establishes standard criteria for uniform reporting and is suitable for acceptance testing between laboratories, provided statistical bias is addressed. The procedure is applicable whenever an index property is desired for quality control.
❓ Frequently Asked Questions
🔍 What is the definition of asphalt retention?
Asphalt retention is the volume of asphalt cement retained by paving fabrics per unit area after submersion in asphalt cement and drainage. It is an index property measured under standard conditions.
💡 Which asphalt cement is recommended for the test?
The standard recommends using Grade PG 64‑22 as defined in Specification D3381/D3381M unless otherwise specified by the purchaser or seller. This ensures consistency in test results.
⚡ What are the required testing atmosphere conditions?
Specimens must be conditioned in air maintained at a relative humidity of 50 to 70 % and a temperature of 21 ± 2 °C (70 ± 4 °F), as per the standard atmosphere for testing geotextiles.
📌 How is the asphalt retention test performed?
Conditioned specimens are weighed, submerged in asphalt cement at a specified temperature, hung to drain in an oven at the same temperature, and then weighed again. The difference in weight per unit area gives the asphalt retention value.