Extensometers for Indirect Tensile Testing of Asphalt – Model 3911

Designed to meet many of the needs for testing asphalt core samples in 100 mm and 150 mm (4 and 6 inch) diameters. It meets test method requirements for strain measurement developed under the U.S. Federal Highways SHRP program.

Epsilon extensometers are COMPATIBLE WITH VIRTUALLY EVERY BRAND OF TEST EQUIPMENT and can be supplied with the correct connector to plug in directly, or supplied with a separate conditioner and amplifier.

WITH EPSILON’S 20+ YEAR HISTORY OF SERVICE to the materials testing community, you know we will be there to stand behind our products when your critical application requires it.

36 EXTENSOMETER MODELS are available in many thousands of variations. Our focus on helping customers has led to the development of models to cover nearly any test method.

For indirect tensile testing, such as for resilient modulus, these extensometers measure the lateral deformation of specimens. They are self-supporting on the sample and clip on in seconds. The traditional way this deformation has been measured was prone to errors caused by slight rocking of the sample as it is loaded. The self-supporting design of the Model 3911 eliminates this problem. This unit will handle the dynamic pulse requirements of resilient modulus testing.

The speed of mounting makes test set-up much faster than with the older method. The pivot mounting used ensures that the specimen contact pads meet the often uneven asphalt surface as well as possible.The measuring range options available allow a wide range of testing, yet can easily measure the sometimes very small displacements required.

The Model 3911 extensometers are strain gaged devices, making them compatible with any electronics designed for strain gaged transducers. Most often they are connected to a test machine controller. The signal conditioning electronics for the extensometer is typically included with the test machine controller or may often be added. In this case the extensometer is shipped with the proper connector and wiring to plug directly into the electronics. For systems lacking the required electronics, Epsilon can provide a variety of solutions, allowing the extensometer output to be connected to data acquisition boards, chart recorders or other equipment.

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  • Model 3911 indirect tensile extensometer for asphalt, for testing per AASHTO TP31 and ASTM D4123.
  • Full bridge, 350 ohm strain gaged design for compatibility with nearly any test system.
  • Easy mounting with built-in breakaway feature should specimen fracture.
  • All standard units have linearity readings of 0.20% or better.
  • Includes the Epsilon Shunt Calibration System for on-site electrical calibration.
  • Rugged, dual flexure design for improved performance.
  • Includes high quality foam lined case.

Download Data Sheet


Excitation: 5 to 10 VDC recommended, 12 VDC or VAC max.

Output: 2 to 4 mV/V, nominal, depending on model

Linearity: ≤0.20% of full scale measuring range, depending on model

Temperature Range: Standard (-ST) is -40 °C to +100 °C (-40 °F to 210°F)

Cable: Integral, ultra-flexible cable, 2.5 m (8 ft) standard

Specimen Size: Adjustable to fit both 100 mm and 150 mm (4 inch and 6 inch) diameter specimens



Download Data Sheet


  • Connectors to interface to nearly any brand of test equipment

Download Data Sheet


Ordering Information

Click table options to configure

Measuring Range¹ i
extension #
+0.76 mm -076M 076M
+1.50 mm -150M 150M
+2.00 mm -200M 200M
+0.030 in -0003 0003
+0.060 in -0006 0006
+0.080 in -0008 0008
Model Number:  3911 – _ _ _
Model Number:
3911 – _ _ _
Model 3911 Available Versions: Consult factory for additional ranges.
Example: 3911-150M: +1.50 mm measuring range


If your unit is in need of service, calibration or repair, initiate the RMA process with us and we will be happy to assist.

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Our 2022 Extensometer Catalog, Version 110 is now available! Not finding something you’re looking for? Ask us about a custom quote.