Rock Testing Capabilities

The Geomechanics Laboratory within the School of Civil Engineering at The University of Queensland offers a range of rock testing, including the following:

  • Static testing:
    • Unconfined Compressive Strength without or with strain-gauging
    • Indirect Tensile Strength (Brazilian or loading disc)
    • Fracture Toughness
    • Shore Sclerescope Hardness
  • Cyclic testing:
    • Applied to any of the above tests
  • Quantitative and qualitative analyses:
    • Backscatter and secondary electron imaging using Scanning Electron Microscope (SEM)
    • X-Ray Diffraction analysis using the Energy Dispersion Spectrometry (EDS) technique


UNIAXIAL COMPRESSIVE STRENGTH

Sample preparation

Sample preparation may require coring and trimming to form cylindrical test specimens conforming to ISRM recommendations (see Figure 1; that is, cylindrical specimens 54 mm in diameter by 134 mm high to give a height to diameter ratio of 2.5 to 3.0, a ratio of specimen diameter to that of the largest rock grain greater than 10:1, and having the ends of the specimen flat to within 0.02 mm).

Figure 1. Brisbane tuff specimens prepared for UCS testing

Specimens may be strain-gauged (and wired) with 2 lateral and 2 axial CEA-06-500UW-350 model Micro Measurements Division (USA) brand strain gauges per specimen (see Figure 2), for measuring both axial (longitudinal) and circumferential strain to determine Young's modulus and Poisson's Ratio.

Figure 2. Strain-gauged Brisbane tuff UCS specimens

Testing

Unconfined Compressive Strength (UCS) testing is carried out using a digitally-controlled INSTRON testing machine (see Figure 3), with measurement of the applied stress, overall sample height, and strain gauges (if fitted), and with reporting of the stress/strain plot, UCS, Secant Modulus (at 50% of UCS), and Young's Modulus and Poisson's Ratio (if strain-gauged).

Figure 3. UCS testing of strain-gauged Brisbane tuff specimen


INDIRECT TENSILE STRENGTH

Sample preparation

Sample preparation involves coring and trimming to form discs conforming to ISRM recommendations (that is, discs 54 mm in diameter by 27 mm thick a diameter to thickness ratio of 2.0).

Testing

Indirect (Brazilian) or loading disc Tensile Strength testing is carried out using a digitally-controlled INSTRON testing machine (see Figure 4), with measurement of the tensile failure load, and with reporting of the Tensile Strength (TS).

Figure 4. Indirect (Brazilian) tensile strength testing of Brisbane tuff specimen


FRACTURE TOUGHNESS

Sample preparation

Sample preparation involves coring and trimming to form discs conforming to ISRM recommendations (see Figure 5; that is, discs 54 mm in diameter by 27 mm thick, with an inner chevron notched crack length of 15 mm and outer crack length of 39 mm).

Figure 5. Brisbane tuff fracture toughness specimens

Testing

Fracture Toughness testing is carried out using a digitally-controlled INSTRON testing machine, with measurement of the tensile failure load, and with reporting of the fracture toughness (see Figure 6).

Figure 6. Fracture toughness testing of Brisbane tuff specimen


SHORE SCLERESCOPE HARDNESS

Sample preparation

Sample preparation involves coring and trimming to form discs conforming to ISRM recommendations (that is, discs 54 mm in diameter by 27 mm thick), as for indirect tensile strength.

Testing

Shore Sclerescope Hardness (SSH) testing is carried out using a Type-D Shore Hardness Tester, IMAI S.K. LTD (see Figure 7), with reporting of SSH, Brinell and Rockwell Hardness values.

Figure 7. Type-D Shore Sclerescope Hardness testing of Brisbane tuff specimen


QUANTITATIVE AND QUALITATIVE ANALYSES

Backscatter and Secondary Electron Imaging using Scanning Electron Microscopy (SEM)

Figure 8. SEM images of Brisbane tuff

X-Ray Diffraction analysis using Energy Dispersion Spectrometry (EDS) technique

Figure 9. EDS spectrum