Resilient Modulus Testing System

Product Code : RMTS

The GDS Resilient Modulus Testing System (RMTS) enables the resilient modulus and permanent deformation of unbound base/sub-base pavement materials to be determined. The system, based around the GDS ELDYN, uses an axially-stiff load frame with a beam mounted electro-mechanical actuator to apply dynamic cyclic axial loads, with a GDS triaxial cell used to confine the test specimen. A number of options are also available for measuring axial deformations, ranging from localised LVDTs to external linear potentiometers.

Discover more dynamic triaxial testing equipment for soil testing.

Key features Benefits to the user
Electro-mechanical load frame: The RMTS load frame supersedes pneumatic actuators in terms of life costs and overall usable performance. Electro-mechanical systems can carry out full load dynamic testing to the stated frequency. Pneumatic systems tend to reduce the available amplitude with load due to the amount of air that needs to be moved from one side of the actuator to the other.
Easy hardware configuration for specific test standards: Numerous RMTS hardware configurations can be selected, enabling resilient modulus and permanent deformation to be determined by following most published test standards. This flexibility allows for a range of specimen sizes to be tested, confining pressure to be measured at various locations, and specimen deformations (axial and radial) to be recorded via localised or external displacement transducers. 
Straightforward test automation via GDSLab test module:
Pre-conditioning, resilient modulus, and permanent test stages can all be automatically performed via the Resilient Modulus test module within GDSLab. 
Axial Load

+/- 5 kN at 5 Hz (upgradeable to +/-10 kN)

Computer Interface


Data Acquisition

16 Bit

Load Range (kN)

5, 10

Operating Frequency (Hz)


Pressure Range (MPa)


Sample Sizes

70, 71, 100, 150

  • Optional upgrade to static and dynamic triaxial testing (Full ELDYN System), with the addition of back pressure control pore pressure transducer and software modules only.
  • Other upgrade options include user defined waveforms, upgrades from 5 kN to 10 kN, bender element system (Vertical, Horizontal, S and P waves), hall effect local strain transducers, unsaturated soil testing.


Tests supported by the Resilient Modulus Testing System, dynamic triaxial testing equipment for soil testing :-

Permanent Deformation

Enables a cyclic axial stress to be applied to the test specimen under a constant confining pressure, with axial deformations monitored to allow the permanent deformation to be determined. Here up to 100 stress stages (different combinations of cyclic axial stress and confining pressure) may be entered, resulting in automation when determining permanent deformation values.

Quick Shear Test

Enables the test specimen to be monotonically-sheared under strain control (i.e., compressed axially at a constant rate) at a constant confining pressure to determine the peak strength of the test specimen.

Resilient Modulus tests

A material’s resilient modulus is actually an estimate of its modulus of elasticity (E). While the modulus of elasticity is stress divided by strain for a slowly applied load, resilient modulus is stress divided by strain for rapidly applied loads – like those experienced by pavements.

Resilient modulus is determined using the triaxial test. The test applies a repeated axial cyclic stress of fixed magnitude, load duration and cycle duration to a cylindrical test specimen. While the specimen is subjected to this dynamic cyclic stress, it is also subjected to a static confining stress provided by a triaxial pressure chamber. It is essentially a cyclic version of a triaxial compression test; the cyclic load application is thought to more accurately simulate actual traffic loading. Please note: Some apparatus may require additional components or software modules to perform certain tests.

Specimen pre-conditioning

Enables a cyclic axial stress to be applied to the test specimen under a constant confining pressure for a specified number of load cycles before the resilient modulus or permanent deformation tests are started. This conditioning phase helps to minimise the effects of imperfect contact between the system platens and test specimen, as well as eliminate effects due to the time interval between specimen compaction and loading.

Standards for the Resilient Modulus Testing System, dynamic triaxial testing equipment for soil testing :-