Basic dynamic triaxial testing system
Basic dynamic triaxial press for resilient modulus (DNIT 134/2018-ME and 135/2018-ME, Brazilian road standards) and permanent deformation (DNIT 179/2018-IE): pneumatic, 20 kN, 1 to 5 Hz, manually set confining pressure.
The basic dynamic triaxial press applies deviator stress pulses under constant confining pressure, combining the stress pairs of each standard. It has a pneumatic drive, microprocessor control and a 20 kN load cell; the dynamic triaxial cell holds two LVDTs and the load cell next to the test specimen.
The software handles setup, configuration, data acquisition, analysis and test reports, with preprogrammed routines for DNIT 134, 135 and 179 (Brazilian road standards).
The test procedures, with formulas and worked examples, are covered in the article on resilient modulus. The four models are compared on the page for the triaxial testing system.
Types of tests
What each test measures, with which fixture and under which standard.
| Test | What it measures | Press and fixture | Standard |
|---|---|---|---|
| Resilient modulus of soils and crushed stone | MR = σd / εr under deviator stress pulses at constant confining pressure | Dynamic load frame, dynamic triaxial cell and pneumatic pressure controller | DNIT 134/2018-ME |
| Permanent deformation | Accumulated deformation over at least 150,000 cycles | Dynamic load frame, dynamic triaxial cell and pneumatic pressure controller | DNIT 179/2018-IE |
| Resilient modulus of asphalt mixtures | MR by repeated-load indirect tensile (diametral compression) testing | Dynamic load frame and diametral compression fixture | DNIT 135/2018-ME |
| Resilient modulus of chemically stabilized materials | MR of soil-cement, cement-treated crushed stone (BGTC), roller-compacted concrete (CCR) and similar materials | Dynamic load frame and DNIT 181 MR fixture | DNIT 181/2018-ME |
Technical specifications
Data from the manual of the dynamic triaxial testing machine (PTD-20k).
Basic dynamic triaxial testing system
| Model | PTD-20k, dynamic triaxial load frame |
|---|---|
| Drive | Pneumatic, microprocessor-controlled, with data acquisition by the software |
| Capacity | 20 kN (4,496 lbf), with a 20 kN load cell |
| Loading frequency | 1 to 5 Hz |
| Pneumatic supply | 10 bar, with air reservoir |
| Piston stroke | 10 mm |
| Control panel | High and low pressure regulators and piston up/down switch |
| Frame | Two screws with vertically adjustable crossbeam |
| Connections | TCP-IP network, USB and four sensor inputs |
| Power supply | 220 V |
| Dimensions | 1,342 × 500 × 714 mm (height × width × length) |
The drawing in the manual gives the machine dimensions: 1,342 mm height, 500 mm width and 714 mm length.
Main features
Pneumatic load actuator (force application unit)
Microprocessor-controlled pneumatic load actuator
Two screws with vertically adjustable crossbeam
Capacity: 20 kN, with 20 kN load cell
Loading frequency: 1 to 5 Hz
Pneumatic supply: 10 bar, with air reservoir
Piston stroke: 10 mm
Two submersible LVDTs in the dynamic triaxial cell
Submersible load cell (can be changed)
Panel with high and low pressure regulators and piston up/down switch
Connections: TCP-IP network, USB and four sensor inputs
USB port for computer connection and control
Automatic stop on force drop, maximum force, displacement or strain
Digital data output
Benchtop model
Electrostatic powder coating for corrosion protection
Rubber feet for damping and vibration isolation
Power supply: 220 V
Manufactured in Brazil
12-month warranty against manufacturing defects (parts and accessories)
Comes with an operating manual in Portuguese
The press, with the parts labeled in the manual, and the pneumatic system panel, where the operator sets the pressures and moves the piston:
Dynamic Triaxial Cell and Fixtures
The dynamic triaxial cell with the parts identified and the dimensions:
Pressurization System
In the basic model, the confining pressure comes from the pneumatic pressurizer (PZP-200kPa): air from an external compressor enters through the valves and the operator sets the pressure on the regulator, reading the value on the pressure gauge, which shows the confining pressure in kPa. It works up to 200 kPa, above the highest confining stress in DNIT 134 (140 kPa).
The pneumatic pressurizer, with the parts identified and the front panel:
Software: main functions
Load cells
The dynamic triaxial press comes with a 20 kN submersible load cell, mounted inside the chamber of the dynamic triaxial cell. Other capacities available on request.
Fixtures
Pressurization system
Pressurization system for volume and pressure control of the triaxial cell.
Triaxial Cell
Triaxial cell built in acrylic and aluminum for triaxial testing of soils.
Load cells
Load cell for measuring the load applied to soil samples.
Frequently asked questions
The most common questions about the basic dynamic triaxial testing system.
Which tests does the dynamic triaxial testing system perform?
Resilient modulus of soils and crushed stone (DNIT 134/2018-ME, a test method of Brazil's federal highway agency), permanent deformation (DNIT 179/2018-IE) and, with the diametral compression fixture, resilient modulus of asphalt mixtures (DNIT 135/2018-ME). With the MR DNIT 181 fixture, it runs the resilient modulus of chemically stabilized materials (DNIT 181/2018-ME).
What are the capacity and frequency of the dynamic triaxial testing machine?
Capacity of 20 kN, with a 20 kN load cell, and frequency from 1 to 5 Hz, with a 10 bar pneumatic supply. The most demanding stress pair of DNIT 134, on a 150 mm test specimen, requires about 7.4 kN.
How does the dynamic triaxial testing machine measure resilient displacement?
With two LVDTs attached to the test specimen inside the dynamic triaxial cell, together with the load cell. For each stress pair, the software calculates the resilient displacement and the resilient modulus.
What is the confining pressure of the dynamic triaxial testing machine?
The dynamic triaxial cell and the pneumatic pressure controller work with air up to 200 kPa. The highest confining stress in DNIT 134 and DNIT 179 is 140 kPa.
What computer does the dynamic triaxial testing machine software require?
Windows 10. The press connects to the computer over a TCP-IP network or USB, and installation is done by Biopdi technical support.
What is the difference between the basic and the automatic dynamic triaxial testing machine?
The press is the same: pneumatic, 20 kN and 1 to 5 Hz. In the basic model, the operator sets the confining pressure on the regulator of the pneumatic pressurizer and reads the value on the pressure gauge. In the automatic model, the confining pressure is controlled automatically.
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Configured for your test
Cell, devices and software selected based on your laboratory's test and standard.
In-house manufacturing, ISO 9001
Installation, training and technical support provided by the people who designed the machine.