An extension of the QU test is the unconsolidated undrained test (UU); this is similar to the QU test but is run at a slower rate in order to measure pore water pressure.

By comparison, effective stresses when measured in a triaxial cell are more complex in their nature, as numerous parameters can be measured. These include back pressure, pore water pressure and volume change; all of which can be used to calculate the required engineering properties.

Effective stress tests are usually referred to as consolidated drained (CD) or consolidated undrained (CU). Generally the CD test is applicable to sands, while both the CU or CD test can be used with clays. There are many special test variations within these basic test groupings.

Our range of triaxial cells and accessories, used in conjunction with other equipment such as load frames, pressure sources and measurement devices, have been specifically designed to meet the wide ranging requirements of modern soil mechanics laboratories. Each system is easy to set up and use, providing accurate and repeatable measurements.

The range of ELE designed and manufactured load frames is the most modern of its kind available to the discerning test laboratory. The range comprises capacities of 50 kN incorporating the latest microprocessor control systems, clear on-board screen displays and a range of other high quality features.

25-3518/01 Yes Yes Yes Yes Yes
25-3700/01 Yes Yes Yes No No

It is particularly important that water from which dissolved air has been removed is used in the pore pressure measurement system and saturation procedures. Any dissolved air in the water will lead to errors in the measurement of pore pressure, particularly at low pressures, and also give slow or incorrect saturation results.

Model No. Self-Contained Capacity, litres
25-1833/01 Yes 15 L

• Working pressure up to 1700 kPa
• All round visibility
• Sample sizes 38 to 100 mm diameter
• Rapid assembly and dismantling
• Accepts a range of interchangeable submersible load transducers
• Maximum piston load 45 kN

This range of precision made triaxial cells has been designed to meet the requirements of the modern soils laboratory. The cells have been treated to minimise corrosion. Particular attention has been paid to the quality of finish between the piston and the head. Final assembly includes the fitting of an O-ring seal and the use of special lubricant to reduce friction to a minimum and eliminate water leakage.

The piston load capacity is designed to accept high horizontal forces which may be present during the final stages of a test. Each cell has five take-off positions drilled in the base for top drainage/back pressure, pore water pressure and bottom drainage. Two no-volume change valves and an anvil for strain gauge/transducer datum are supplied for fitting to the cell.

A feature of these cells is that they all accept a single diameter piston. The internal height is such that a range of submersible load transducers can be fitted without any modification. Each cell will accept a range of base adaptors and various accessories for testing a wide range of specimens

Model No. Cell Size Weight, kg Max. Specimen Size Vertical Clearance Horizontal Clearance
25-4157 100 mm 14.3 kg 100 x 200 mm 515 mm 255 mm
25-4117 70 mm 7.3 kg 70 x 140 mm 430 mm 180 mm
25-4047 50 mm 4 kg 50 x 100 mm 380 mm 155 mm

Although all products are treated to inhibit corrosion, certain aggressive materials may attack the metal components. Examples of this are samples obtained from the seabed or containing high concentrations of sulphates or chlorides.

Where aggressive materials are to be tested, ELE will be pleased to offer advice on any special requirements.

Model No. Desc
25-4200 Piston Restraint Clamp
25-8090 Silicon Grease Lubricant

Each cell will require the correct size of specimen base adaptor relative to the size (diameter) of sample tested. All base adaptors are double perforated for bottom drainage/pore pressure measurement. They are supplied complete with a solid disc for use in tests where no drainage is required. 

Model No. 100 mm Cell 70 mm cell (25-4117) 50 mm cell (25-4157) Specimen
25-4174 - Yes - 50 mm
25-4166 - - Yes 38 mm
25-4186 Yes - - 100 mm
25-4176 - Yes - 70 mm
25-4168 - - Yes 50 mm

Various methods of measuring axial displacement, load, pressure and volume change can be supplied. All devices comply with the accuracy specified in BS 1377; ASTM D2850, D4767. All transducers transducers are supplied with a calibration certificate.

Variious methods of axial displacement and load can be supplied. All devices comply with the accuracy specified in BS 1377, ASTM D2850, D4767. All transducers are supplied with a calibration certificate

Model No. Type Capacity, kN
78-0760 Load ring 28
27-1553 S-Type 10
27-1555 S-Type 25
27-1575 Submersible 10
78-0260 Load ring 4.5
27-1551 S-Type 5
27-1573 Submersible 5
27-1293 Stainless Steel distance piece for use with submersible loads cells -
78-0860 Load ring 50

Variious methods of axial displacement and load can be supplied. All devices comply with the accuracy specified in BS 1377, ASTM D2850, D4767. All transducers are supplied with a calibration certificate

Model No. Desc
25-4210 Dial gauge 25mm travel x 0.01mm divisions
27-1617 Axial strain transducer assembly 50mm travel

The provision and use of constant pressure systems in the geotechnical laboratory is essential if testing methods and equipment are to be fully utilised. Generally a number of independent and variable pressure sources will be required in a laboratory. Accurate and reliable monitoring systems will also be required, which may range from a single pressure guage through a whole series of transducers.

Where a laboratory requires a number of constant, but independent and variable pressure sources, the use of a pnuematic compressor is recommended. Depending on the capacity and volume of the unit, a series of pressure sources can be provded to various test stations around the laboratory.

Compressed air must be controlled and delivered to a system designed to transfer the controlled pressure to the fluid (usually water), which applies the various test pressures, e.g., a confining pressure in a triaxial test. The pressure reducing panel share used in conjunction with a bladder-type air/water interface assembly. Each individual pressure take off from the reducing panel will require a bladder interface assembly. Connection of the reducing panels to the compressor/water trap outlet and to other reducing panels requires the use of nylon tubing.

Model No. Desc
26-1746/10 Replacement bladder
26-1746 Bladder-type air/water pressure assembly
26-1769 Nylon tubing
83-1730/01 Air Compressor Unit
26-1872 Six-Way Pneumatic Pressure Control Panel
26-1760 Pneumaticpressure reducing panel
26-1800/01 Pressure Test 1700 Oil/Water Constant Pressure System
83-1735/01 Air Compressor Unit

• Modular system for flexibility
• Wall mounting
• Four outlets
• 6 mm diameter pipework for quick filling and draining
• Standard type valves on all units - on/off with no volume change
• Ideal system for geotechnical laboratories

This modular system provides flexibility and cost saving by enabling only those units that are relevant to the particular testing requirements to be selected. It is simple to update the system with the addition of other units, which can be quickly connected together.

The units may be used with a variety of pressure systems, such as pnuematic and oil/water and are designed to accept pressures of up to 1700 kPa where appropriate.

Model No. Desc
26-1880 Universal Pump and Pressure Indicating Panel 1700Kpa
26-1865/10 Pressure Gauge 1700Kpa (250Psi) 250mm Diameter.

• 0 to 1700 kPa (250 lbf/in²) fully variable
• Continuous constant pressure control
• One litre capacity

The ELE oil/water constant pressure system, PressureTest 1700, is extemely versatile and can be used in conjunction with a wide range of test equipment. The unit provides continuous variable pressure up to 1700 kPa. Pressure is increased or decreased simply by turning a control wheel.

The apparatus is supplied without a gauge for those customers who have suitable pressure monitoring equipment. A digital pressure gauge is offered as an accessory. The machine features a clear hydraulic/water interface reservoir and up to one litre capacity of water is available under pressure.

Model No. Desc
26-1800/01 Pressure Test 1700 Oil/Water Constant Pressure System
26-1805 Oil 5 Litres T46
27-1620 Digital Pressure Gauge