Epsilon MODEL 3909 Extensometers for Simple Performance Testing of Asphalt

Epsilon MODEL 3909 extensometers are designed to measure dynamic modulus of hot mix asphalt in accordance with AASHTO TP062, and to measure axial displacements in the simple performance tests as outlined by NCHRP Report 465.

Generally, the Model 3909 is configured as two axial modules with independent outputs that can measure sample deformations in two locations.

However, it is possible to mount the extensometer as a single unit or up to four on a specimen. The Model 3909 rapidly clips onto gage points mounted in accordance with the test requirements.

The Model 3909 can be quickly mounted due to the presence of magnets at its each end that snap instantly in place on the steel gage points affixed to the test specimen.

This quick mounting is most advantageous in testing of preconditioned samples that are cooled or heated before the sample temperature changes noticeably. Epsilon offers extensometers with modules rotated 90° for use within triaxial cells.

The full-scale measuring range of the standard Model 3909 is 0.5mm. The Model 3909 extensometers come with gage points with optional gluing fixtures. It is possible to convert two standard 3909 units to the Model 3910 with the addition of optional gauge length adapters.

As strain gauged devices, the Model 3909 extensometers shows compatibility with virtually any electronics intended for strain gauged transducers.

They are most often coupled to a test machine controller. The signal conditioning electronics for the extensometer are generally integrated to the test machine controller or may often be included.

In this case, the extensometer is supplied with the proper connector and wiring for direct plugging into the electronics.

Epsilon provides a range of solutions for systems without the required electronics, enabling connection of the extensometer output to equipment such as chart recorders and data acquisition boards.

Key Features

The following are the key features of the Model 3909 extensometers:

  • Full bridge, 350Ω strain gauged design for compatibility with nearly any test system
  • For measuring dynamic modulus of hot mix asphalt per AASHTO TP062 and for simple performance testing per NCHRP Report 465
  • Rugged, dual flexure design for better performance
  • Easy mounting, attaches with magnets, which allows dynamic testing to 40Hz
  • All standard units feature linearity readings of 0.20% or better
  • Features high quality foam lined case

Epsilon MODEL 3909 Extensometers for Simple Performance Testing of Asphalt

Model 3909-0400 with 4 inch gauge length
Model 3909 gluing fixture for 180° spacing
Model 3909-0400 with 4 inch gauge length

Available Versions of Model 3909

The Model 3909 is supplied in intermediate and larger gauge lengths upon special order:

Epsilon also offers other configurations upon request.


Options available include gauge length adapters, connectors to interface to virtually all brands of test equipment, and gluing fixture for gage points.

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