Uniaxial & Triaxial Accessories

ASTM D5407 | ASTM D7012 | ASTM D3967 | ISRM
Hoek triaxial cells are offered in five models of different size; each one consists of the following:
  • A cell body (1), complete with two quick release self sealing couplings, for the introduction of the hydraulic oil and cell pressure, and for air outlet  and saturation of the chamber respectively.
  • Two end caps (2), screwed into the cylindrical cell body.
  • Upper (3) and lower loading caps (4) with spherical coupling.
  • Two female spherical seating (5) connected to the loading caps (3) and (4) for the correct transmission of the axial load from the loading frame of the compression machine to the specimen.
  • A rubber sealing sleeve (6) to separate the specimen from the cell fluid. Although each sleeve can be used for several tests, an order of five spare sleeves is recommended.
  • Measurements of axial and radial strain are carried out with the use of electric strain gauges (7), both in vertical and horizontal direction, directly glued on the lateral surface of the specimen. The wiring connections are passed within the rubber sleeve  trough the cell body and loading cap. Each strain gauge must be connected to a proper device (see 82-P0398) to complete and balance the Wheatstone bridge.

The strain gauge measurements can be performed by automatic or semi automatic testing systems. The cell pressure and saturation pressure for permeability tests are carried out by the use of appropriate equipment.

32-D0553: Hoek cell, AX, for specimen dia. 30.10x60 mm, total height 213 mm
32-D0554: Hoek cell, 1.5 in., for specimen dia. 38.10x75 mm, total height 264 mm
32-D0555: Hoek cell, BX, for specimen dia. 42.04x85 mm, total height 263 mm
32-D0556: Hoek cell, NX, for specimen dia. 54.74x100 mm, total height 304 mm
32-D0557: Hoek cell, HQ, for specimen dia. 63.50x127 mm , total height 310 mm

Accessories for compression test
32-D0556/A: Pair of load spreader for uniform load distribution
32-D0556/B: Distance pad to reduce the vertical clearance of the compression machine
32-D0556/H: Hoek cell holder compatible with Hoek cell codes 32-D0553, 32-D0554, 32-D0555 and 32-D0556. Not required for Hoek cell HQ type code 32-D0557

It is also recommended the use of a Specimen extruder to extrude the rock sample from its jacket thus avoiding to empty the confining fluid.

32-D0577/B: Specimen extruder for Hoek cells series 32-D055x, requires adaptors

32-D0577/1: Extruder adapter set for specimen AX, for cell 32-D0553
32-D0577/2: Extruder adaptor set for specimen 1,5 inch, for cell 32-D0554
32-D0577/3: Extruder adaptor set for specimen BX, for cell 32-D0555
32-D0577/4: Extruder adaptor set for specimen NX, for cell 32-D0556
32-D0577/5: Extruder adaptor set for specimen size HQ, for cell 32-D0557
Strain gauges for uniaxial and triaxial tests provide a very accurate electrical signal, strictly proportional to the strain of the specimen submitted to load application, for determining the Elastic Modulus and strength characteristics as alternative to the Compressometer-Extensometers.

82-P0390: Strain gauge, 9.53 mm gauge length. Pack of 5
82-P0391: Strain gauge, 20 mm gauge length. Pack of 10
82-P0392: Strain gauge, 30 mm gauge length. Pack of 10
82-P0393: Strain gauge, 60 mm gauge length. Pack of 10

82-P0399/1: Connecting terminals, 50 pairs sheet

They can be applied to the specimen surface by a special Adhesive-Catalyst agent and other accessories all included in the Strain gauge application kit.

82-P0399/C: Strain gauge application kit including: conditioner, neutralizer, acetone, tweezer, adhesive with catalyst agent, 100 m of bipolar cable, solder, soldering iron, scalpels, scissors, duct tape, sellotape, sandpaper and carrying case.

82-P0398: Compensation device for up to 4 Wheatsone bridges with ¼ or ½ bridge setup

82-P0399/P22: Adhesive and catalyst agent to glue the strain gauge to the specimen

Up to 4 strain gauges ¼ bridge, and up to 8 ½ bridge, can be directly connected by one or two interfaces 82-P0398 to MCC8 and ADVANTEST 9 Control consoles  which are suitable for cyclic loading and automatic determination of the Modulus of Elasticity.

Strain gauges can also be connected, by one or two interfaces 82-P0398, to a suitable data logger as, for example, the Datalog 8, 82-P9008.
We propose two compression device models for indirect tensile test (splitting test) conforming to ASTM D3967 and to ISRM Specifications.
 
32-D9032/H: Compression device for indirect tensile tests on rock specimens conforming to ASTM D3967. Supplied complete with distance piece for specimen dia. 54 mm

This apparatus, originally developed for testing in compression cement specimens, can also be used for splitting tensile test on rock disks with dimensions from dia 54 mm to 64 mm.

32-D9032/NX: Compression device for indirect tensile test on rock specimens NX type (dia. 54.74 mm) consisting of two steel loading jaws, guiding pins and half ball bearing. Conforming to ISRM specifications.
32-D9032/HQ: Compression device for indirect tensile test on rock specimens HQ type (dia. 63.5 mm) consisting of two steel loading jaws, guiding pins and half ball bearing. Conforming to ISRM specifications.

All models above can be used as accessories with a suitable universal tester.

This compression jig is strictly compliant to ASTM D7012 Rock core specimens Test Methods, in particular the spherical seat / compression plates / specimen diameters’ ratios fall within the prescriptions.

32-D9035: Compression device for rock core specimens with dia. from 54.7 mm (NX) to 63.5 mm (HQ) conforming to ASTM D7012:
- upper spherical seat and compression platens dia. 80 mm with hardness 58 HRC
- loading head stroke: 66 mm
- vertical clearance: 167 mm
- overall height: 333 mm. 
- supplied with distance pieces to reduce the vertical clearance: 2x h 30 and 1x h 22 mm
- max. loading capacity: 1,200 kN
 
It consists of a heavy duty twin-column frame, a spherically seated upper platen hold by calibrated springs and a lower platen centred on the frame base. The high stiffness structure and the high performance steel of the spherical seat make this device particularly suitable for high strength rock specimen featuring brittle properties and explosive failure.
It shall be preferably fixed on the compression machine piston head by the threaded pin included in the supply compatible with all CONTROLS compression frames / machines.