EN 13302 Determination of Dynamic Viscosity of Bituminous Binder Using Rotary Shaft Apparatus

The European standard “EN 13302 Bitumen and bituminous binders - Determination of dynamic viscosity of bituminous binders using a rotary shaft apparatus” describes the method for determining the dynamic viscosity of various bituminous binders (modified and unmodified bituminous binders, bituminous emulsions, withdrawn and fluidized bituminous binders) using a rotary shaft apparatus (coaxial viscometer).

This specifies standard application temperatures, but dynamic viscosity can be measured at other temperatures if required. Similarly, measurements at standard shear rate values ​​can be replaced or supplemented with measurements at additional shear rates if necessary.

In principle, torque applied to a rotating shaft (e.g., a cylinder) in a special sample container holding the test specimen measures the relative resistance of the shaft to rotation and provides a measure of the dynamic viscosity of the specimen. To obtain the true dynamic viscosity at the test temperature, it may be necessary to apply a shape factor.

Since non-Newtonian viscosity values ​​reflect the behavior of the fluid and the measurement system, not unique material properties, it is acknowledged that measurements made using this method may not always predict performance under operating conditions. Comparisons between non-Newtonian viscosities should only be made for measurements taken under similar shear stress conditions.

Bitumen and bituminous binders are widely used in road construction, roofing, waterproofing systems, and industrial applications. One of their most important rheological properties is dynamic viscosity, which describes the material's resistance to flow under an applied force. Determining dynamic viscosity using a rotary shaft device is a method described in detail in the EN 13302 standard.

This standard specifies a procedure for measuring the dynamic viscosity of bituminous binders at high temperatures using a rotary viscometer equipped with a shaft. The test is applicable to:

• Asphalt paving bitumen
• Polymer modified bitumen
• Industrial bitumen
• Bituminous binders used in asphalt production.

This method provides viscosity values ​​that help characterize the usage and performance characteristics of binders during production, transportation, and application.

The test principle is based on the resistance encountered by a rotating shaft in a heated sample of bituminous binder. The shaft is immersed in the binder and rotated at a constant speed. The device measures the torque required to make the shaft rotate. This torque is directly related to the viscosity of the material. Higher torque indicates:

• Higher viscosity
• Greater resistance to flow.

Conversely, lower torque indicates the following:

• Lower viscosity
• More stream features

The device automatically converts torque measurements into dynamic viscosity values.

The equipment used in the tests includes the following:

• Rotary viscometer
  • Motor-driven rotary shaft system
  • Digital torque measurement
  • Variable rotational speeds
• Temperature control system
  • Heating chamber or thermally controlled sample container
  • Precise temperature regulation
• Miller: Different shaft geometries can be used depending on the following:
  • Viscosity range
  • Connector type
  • Test temperature
• Sample containers: Specialized containers designed to ensure consistent shaft immersion depth and temperature distribution.

The test generally follows these steps:

• Sample preparation: The bituminous binder is carefully heated until it becomes sufficiently fluid for testing.
• Temperature conditioning: The sample is typically kept at the following temperatures:
  • 135 degrees
  • 150 degrees
  • 165 degrees
  • Other temperatures specified in the product standards.
• Shaft installation: A suitable shaft is selected and immersed in the sample according to the requirements of the standard.
• Measurement: As the shaft rotates at a predetermined speed, the viscometer records the torque resulting from the resistance of the binder.
• Calculation: The device calculates dynamic viscosity, typically expressed in units such as Pascal-seconds and millipascal-seconds.

Several factors can significantly affect viscosity measurements:

• Temperature: Bitumen viscosity is highly dependent on temperature. Even small temperature variations can cause significant changes in the measured viscosity.
• Shaft selection: Incorrect shaft selection can lead to the following:
  • Excessive torque
  • Insufficient torque
  • Reduced accuracy
• Rotational speed: Bituminous binders can exhibit non-Newtonian behavior, making rotational speed a crucial parameter.
• Sample homogeneity: Poorly mixed samples can yield inconsistent results.

The described method is used in the following areas:

• Quality control:
  • Verification of production consistency.
  • Party acceptance tests
• Product development:
  • Evaluation of new binder formulations.
  • Evaluation of polymer-modified binders
• Asphalt production:
  • Determining mixing temperatures.
  • Determining pumping temperatures.
  • Assessment of processability
• Research and development:
  • Rheological characterization
  • Performance studies

Dynamic viscosity is an important parameter because it affects the following:

• Pumpability of binders
• Storage stability
• Mixing efficiency with aggregates.
• Coating performance
• Compaction properties of asphalt mixtures
• Energy consumption during production

Viscosity measurement is particularly important for polymer-modified bitumen because modifications can significantly alter flow behavior.

The advantages offered by the rotary shaft method are as follows:

• A relatively simple process.
• Good repeatability.
• Suitable for a wide viscosity range.
• Quick test
• It is widely accepted internationally.
• Suitable for routine quality control.

Some of the limitations included in this standard are:

• The measurements are sensitive to temperature control.
• Some high-strength binders may exhibit shear-related behavior.
• Results obtained at one temperature may not represent performance at other temperatures.

In conclusion, the EN 13302 standard defines a standardized method for determining the dynamic viscosity of bituminous binders using a rotating shaft apparatus. This test method allows manufacturers, laboratories, and road authorities to assess flow properties, manufacturing suitability, and quality consistency by measuring the resistance of heated bitumen to shaft rotation. Accurate viscosity measurement is crucial for the proper handling, mixing, transportation, and long-term performance of bituminous materials used in road pavements and industrial applications.

For many years, our organization, with its competent and experienced staff, has been understanding the needs of its clients, providing the advanced testing services they require, and assisting them in the establishment, implementation, and improvement of management systems. Within this framework, we also provide testing services in accordance with the EN 13302 standard.