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D2170 – Standard Test Method Technical Guide
🔬 Scope, Materials, and Applicability
Standard Test Method D2170/D2170M-24 defines the procedures for determining the kinematic viscosity of liquid asphalts, road oils, and distillation residues of liquid asphalts at 60 °C [140 °F], and for liquid asphalt binders at 135 °C [275 °F]. The method is applicable across a broad viscosity range of 6 to 100,000 mm²/s [cSt]. Precision limits have been specifically validated for the range from 30 to 6000 mm²/s [cSt] for the specified material types and temperatures.
⚙️ Test Procedure and Critical Methodological Assumptions
The test method operates on the fundamental assumption that the asphalt binder behaves as a Newtonian fluid during the measurement. The kinematic viscosity is determined by measuring the flow time of a fixed volume of liquid under gravity through a calibrated capillary viscometer.
Modified or recovered asphalt binders are often non-Newtonian. When non-Newtonian flow is present, the calculated shear rate and viscosity may be invalid. The standard recommends verifying Newtonian behavior by measuring viscosity with capillary viscometers of different sizes. If results differ significantly, the material is non-Newtonian, and the defined precision limits in Section 11.1 shall not be applied.
| 🟦 Standard Reference | 📏 Test Parameter | 🎯 Specified Value / Range |
|---|---|---|
| Section 1.1, 11.1 | Test Temperature (General Materials) | 60 °C [140 °F] |
| Section 1.1, 11.1 | Test Temperature (Asphalt Binders) | 135 °C [275 °F] |
| Section 1.1 | Total Application Viscosity Range | 6 to 100,000 mm²/s [cSt] |
| Section 11.1 / Note 1 | Validated Precision Range | 30 to 6000 mm²/s [cSt] |
| Section 1.1 | Key Applicable Materials | Liquid asphalts, road oils, distillation residues, asphalt binders |
🔧 Technical Tip: Verifying Newtonian Flow in Asphalt Binders
When testing modified or recovered asphalt binders, always verify the Newtonian behavior assumption. Run the test using at least two capillary viscometers with significantly different tube diameters. A substantial difference in the calculated kinematic viscosity is a clear indicator of non-Newtonian behavior. In this case, the standard precision limits do not apply, and the derived shear rate cannot be reported as valid.
📊 Calculations, Units, and Safety
Results from this test method can be used to calculate dynamic viscosity. This requires knowledge of the material’s density at the test temperature. The specific calculation formula is provided in Annex A1 of the standard. The standard provides values in both SI units and inch-pound units. To maintain conformance with the standard, each system of units must be used independently; combining values from the two systems can lead to nonconformance.
⚠️ Warning: Mercury Safety and Handling
Mercury is designated a hazardous material by the EPA and many state agencies. It poses significant risks to health and can damage equipment. This test method warns users to exercise extreme caution when handling mercury and mercury-containing products. Always consult the product’s MSDS/SDS and the EPA’s mercury website (http://www.epa.gov/mercury/faq.htm) for comprehensive safety and disposal guidelines. Be aware that the sale of mercury or mercury-containing products may be restricted by state law.
❓ Frequently Asked Questions
🔍 What is the formal ASTM designation for this standard?
The formal designation is D2170/D2170M-24. The standard was previously issued under the designation 319/84 (89).
💡 Why does the standard specify two distinct test temperatures?
The standard specifies 60 °C [140 °F] for liquid asphalts, road oils, and distillation residues to assess their flow characteristics at moderate temperatures. It specifies 135 °C [275 °F] for asphalt binders to ensure they are sufficiently fluid and within a measurable viscosity range during hot-mix applications and testing.
⚡ What is the maximum kinematic viscosity covered by the test method?
The test method covers an application range from 6 up to 100,000 mm²/s [cSt]. However, precision data is only established for the range of 30 to 6000 mm²/s [cSt]. Measurements outside this precision band should be interpreted with caution.
📌 What should be done if a sample exhibits non-Newtonian behavior?
If non-Newtonian behavior is suspected (verified by using capillary viscometers of different sizes), the calculated shear rate from this method is invalid. The standard defines that its precision limits do not apply to non-Newtonian asphalt binders under these conditions.