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Hoek Cell for Triaxial Test (Hoek-Cell)

Hoek Cell

The Hoek Cell is a simple and inexpensive triaxial cell that tests triaxial strengths of rock or concrete core specimens up to a pressure of 70 MPa. They are designed to accept samples of X, AX, 1.5 in, BX, NX and NX sizes and offer a fast and effective way of dealing with samples with accessories for permeability testing.

The Hoek cell is made of a hollow steel cylinder with two removable end caps. The cylinder can withstand internal hydraulic pressure of up to 70 MPa.

Two hardened and ground spherical steel seats apply an axial load to the flattened ends of the sample. In addition, a ‘jacket’ with the same diameter of the sample and a rubber sealing sleeve works to separate the specimen from the cell fluid.


  • Cylindrical cell made of annealed special steel
  • Hoek cells available in different sizes e.g. X, AX, BX and NX
  • Confining pressure up to 70 MPa
  • Load spreader to uniformly distribute load
  • Spacers to adjust vertical distance
  • Hoek Cell holder
  • Rock specimen extruder
  • Rubber sleeve for rock specimens
  • Drainage valve to flush and release cell pressure
Type of load frame  Hydraulic / Servo-hydraulic
Compression load   Up to 2,000KN
Tension load capacity Up to 1000KN
Confining pressure  Up to 70 MPa
Pore pressure  Up to 70 MPa
Frame stiffness Up to 2,500 kN/mm, 2.5 X 10^9 N/m
Stroke  50 mm, optional up to 150 mm
Hardness  55 HRC / Customised
Sample sizes  Up to NX or upper
  • Permeability and hydraulic fracturing tests on rock samples by using hardened upper/lower end caps and upper spherical end cap guidance
  • Ultrasonic testing equipment
  • Connecting ports for permeability, ultrasonic and hydraulic fracturing tests
  • ASTM D-2664
  • Standard Test Method for Triaxial Compressive Strength of Undrained Rock Core Specimens Without Pore Pressure Measurements (withdrawn 2005, replaced by ASTM D7012)

  • ASTM D-5084
  • Standard Test Methods for Measurement of Hydraulic Conductivity of Saturated Porous Materials Using a Flexible Wall Permeameter

  • ASTM D-5407
  • Standard Test Method for Elastic Moduli of Undrained Intact Rock Core Specimens in Triaxial Compression without Pore Pressure Measurement (withdrawn 2005, replaced by ASTM D7012)

  • ASTM D-7012
  • Standard Test Methods for Compressive Strength and Elastic Moduli of Intact Rock Core Specimens under Varying States of Stress and Temperatures

  • ASTM D-7070
  • Standard Test Methods for Creep of Rock Core under Constant Stress and Temperature

  • Triaxial shear test
  • Permeability test
  • Hydraulic fracturing test
  • Ultrasonic velocity measurement
  • Creep test