The GCTS Resilient Modulus Testing Systems are designed to quickly and easily perform resilient modulus tests on 2.8, 4, or 6 inch diameter specimens. The MRT Series of systems can be provided with a variety of load capacities and cell sizes to accommodate some or all of these specimen diameters, and come fully-configured with external and internal load cells and displacement sensors matched to the tested specimen diameter as required by the AASHTO standard.
The systems are fully computer controlled and the software features built-in AASTHO, SHRP, and NCHRP test sequences, along with the capability to perform user-defined test sequences. With this software, the contact stress is automatically adjusted according to the testing procedure as selected, and the operator can set a variety of available waveforms for dynamic loading, include haversine, sine, square and triangular, and user-defined waveforms. Optional peak & valley compensation ensures proper and quick matching of the load parameters. Real time displays of the prescribed versus actual dynamic load or the dynamic deformation measurements by each sensor are always present. The deformation ratio of the two sensors, Rv (to ensure that the two deformation sensors are in agreement) and Mr are also calculated in real time. During export, curve fitting is done to fit the results to models that predict Mr as a function of σm, σd, and cell pressure. Four different functions are calculated automatically as required by AASHTO and NCHRP procedures:
- Mr = K1 (σm)K2
- Mr = K1 (σd)K2
- Mr = K1 (σd)K2 CPK3
- Mr = K1 Pa[(Θ-3K6)/Pa]K2 [τoct/Pa + K7]K3
The system is also capable of testing asphalt pavement specimens. For testing these specimens at different temperatures, an optional environmental chamber can be provided. This chamber can accommodate triaxial, indirect tension, beam flexural fatigue, dynamic modulus and all the other testing fixtures GCTS offers. Temperatures of ‑30° to +150°C (with liquid nitrogen boost) can be achieved with this option.