All testing machines require sensors for measuring physical quantity during tests. This section includes all the electronic measuring devices to be fitted on standard or automatic machines typically used in a soil mechanics laboratory such as load cells, displacement transducers, pressure transducers and volume change devices.
Submersible (internal) load cells have been designed to work inside the triaxial cells.
Submersible load cells have been designed to work inside the triaxial cells. They have a lower hysteresis and very good linearity tighter with a substantial overload safety feature. Advantages:
They are supplied complete with rams to suit Banded triaxial cells or standard triaxial cells . Standard models of submersible cells are also supplied complete with extension kit for small samples.
The versions for Dynamic testing are practically identical to the standard models except for the connections to the system.
Submersible load cells fit with rams and models of compatible triaxial cells
| Load cell model | Cap. [kN] | Compatible Triaxial cells | Ram dia. [mm] |
| 28-WF6350 | 1 | 28-WF4050 | 15.5 |
| 28-WF6352 | 5 | ||
| 28-WF6354 | 10 | ||
| 28-WF6351 | 1 | 28-WF4070, 28-WF4100, 28-WF4150 28-WF4170, 28-WF4171 | 25.0 |
| 28-WF6353 | 5 | ||
| 28-WF6355 | 10 | ||
| 28-WF6356 | 25 | ||
| 28-WF6357 | 50 | ||
| 31-WF7117 | 5 | 28-WF4070, 28-WF4100, 28-WF4150 28-WF4170, 28-WF4171 | 25.0 |
| 31-WF7118 | 10 | ||
| 31-WF7119 | 25 |
Note: All submersible cells can be supplied, on request, with traceable calibration certificate. They are identified by the suffix /C after the code number. Ex. 28-WF6350/C.
Used for measuring the axial force applied to soil sample.
Used to measure the axial force applied to the specimen in the triaxial cells or in a shear machine Complete with connector to the upper beam of Triaxial load frames or shear machine
Note: All models can be supplied, on request, complete with traceable calibration certificate. They are identified by the suffix C after the code number. Ex. 28-WF0370/TC.
Used for measuring axial deformation on soil sample
Standards ASTM D8079
Potentiometric transducers
Linear potentiometric transducers are used with various testing machines and apparatus as, for example, Consolidation apparatus, Shear testing equipment and Triaxial testing equipment to fit triaxial cells.
LVDT transducers
Used in the Dynamic triaxial systems.
All the above transducers are supplied with mounting block but have to be completed with the appropriate mounting bracket for connection to triaxial cells. See accessories.
*PRO-COMPACT closed-loop is an innovative mechanical and electronic control that combines orthogonality of the load, pendulum motion of the head and sinusoidal non-friction forward-reverse carriage movement. This results in an optimally compacted sample that features Planarity Regularity and hOmogeneity (PRO).
The software is able to combine a load/displacement compaction. This procedure provides at the beginning of the test a controlled displacement compaction, which can grant a flat surface of the compacted slab, followed by a load compaction phase, which can replicate the real compaction on the road surface.
Potenziometric transducers
LVDT transducers
Mounting bracket for displacement transducer, to fit 15.5mm triaxial cell ram for (28-WF4050 and 28-WF0410/B)
Mounting bracket for displacement transducer, to fit 25mm triaxial cell ram for 28-WF4070,28-WF4100, 28-WF4150; 28-WF0411/B and 28-WF0416/B)
The slab compactors can compact asphalt slabs to a target density applying specific loads.
This apparatus, when connected to data acquisition system, provides an electrical signal directly proportional to the volume of water flowing through the unit. The apparatus comprises a piston connected to a 25 mm travel linear transducer and sealed against a precision-machined calibration chamber so thet the the linear movement of the piston is exactly proportional to the volume of water in the calibration chamber. The apparatus includes the panel with reversing valve system to measure the water flow in both directions.
Used for measuring pore water pressure and acquiring cell pressure, back pressure.
Pressure transducers are used for the measurement of cell pressure, back pressure, pore pressure (water or air).They have to be connected to triaxial cells by the suitable De-airing block. See accessories.
The transducers are base on the extensimetric measurement principle with strain gauges on the metal base.
Two series are available according to the compatibility with the machine, please refer to the technical specification and transducers compatibility table below.
| Code | 28-WF630X | 28-WF630X/A |
| Input voltage | 1-10 | 1-10 |
| Output voltage | 10mV/V | 1.5 mV/V |
| Resolution | infinite | infinite |
| Accuracy | ±0.25 FSO | ±0.25 FSO |
| Temperature [°C] | -40 to +85 | -40 to +105 |
| Temperature effect*[FS/°C] | ±0.015% | ±0.01% |
| Removable cable | No | Yes |
| Dimensions** [lenght x dia.] | 5.8 x 2.55 | 15.2 x 2.7 |
| Weight [g] | 100 | 130 |
Where:
X = 0 : 1000 kPa
X = 1 : 2000 kPa
X = 2 : 3500 kPa
* Typical thermal zero and span coefficients
** nipple included
