Asphalt Viscosity Testing

ASTM D4402

ASTM D4402

Asphalt testing can serve many purposes, ranging from quality control to processing behavior and field performance prediction. Asphalt is subjected to such a wide range of temperatures throughout its lifecycle, from mixing, handling, and application to its final service environment. Reliable, repeatable laboratory testing can result in valuable data that allows manufacturers to optimize product performance at every step.

One such asphalt test is ASTM D4402. ASTM D4402 measures the viscosity of asphalt and bitumen during handling, mixing, and application, specifically the temperature associated with each of these processes. Understanding the behavior of the asphalt material at different temperatures is important for streamlining each process and ensuring proper, long-lasting application. Understanding viscosity is also important for determining the ease and efficiency of placement, compaction, and other workability characteristics of asphalt materials.

It is worth noting that, depending on the temperature and other conditions, it is possible to observe non-Newtonian behavior in asphalt materials during asphalt viscosity testing. Because of this, data collected when the asphalt sample under test displays non-Newtonian behavior should not necessarily be considered a meaningful predictor of field performance. ASTM D4402 does include specific guidance on how to interpret non-Netwonian behavior, how to use the data, and how it contributes to field performance predictions of asphalt materials.


The asphalt viscosity test method described in ASTM D4402 uses a rotational viscometer to measure a material’s resistance to rotation at a given temperature. A thermal chamber heater is also used to bring the sample up to the appropriate temperature before testing begins. Once both instruments have been prepared, the asphalt test sample is added to the sample chamber. Accurate sample volume is critical to ensuring accurate test results. The sample is then brought to temperature before motor rotation begins.

Generally, the sample is subjected to motor rotation for about three minutes. Torque and speed measurements are recorded a total of three times, at one-minute intervals, to calculate the viscosity of the bitumen sample. Some rotational viscometers record this data automatically, while others require manual measurement. The process is repeated at each temperature designed by the test method. 

In the event that torque readings are above or below the instrument’s capacity, the test technician may need to adjust the speed of rotation of the rotational viscometer. Specific criteria and instructions for these adjustments are detailed in ASTM D4402. ASTM D4402 also explains how to assess results for repeatability and reproducibility.

The three recorded measurements are averaged to determine a final figure. The data can then be used to establish appropriate handling, mixing, and application temperatures for asphalt and bituminous materials.


Asphalt and Construction Material Testing From ACE

At ACE Laboratories, we’re proud to have a wealth of team members with years of experience in the development and testing of asphalt, bituminous materials, and other construction products including joint and crack sealants, roofing materials and coatings, adhesives, and more. From compound development and service life prediction to failure analysis and competitive benchmarking studies, our experts can develop custom testing protocols to support your specific goals or conduct standardized testing in an independent, third-party laboratory environment.

In addition to accurate, repeatable data, ACE Laboratories can deliver the fastest turnaround times in the industry. You can count on ACE to help you maintain your production timelines and launch schedule and help you make confident, timely decisions about product development and product.

To learn more about asphalt viscosity testing and other construction material testing services form ACE, talk to a member of our team >

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