A road's surface is a vital component of a pavement, providing a safe, dust-free vehicle/pavement interface for the passage of vehicles.
"Drivers judge the quality of a road by its surfacing characteristics, such as skid resistance, appearance (cracking, patching), noise and smoothness," said the Australian"It [surfacing] protects the pavement structure from moisture infiltration and wear and tear. It is essential, therefore, that road authorities provide bituminous surfacings with the appropriate properties and life to avoid deaths, injuries and potential litigation in cases where vehicles are involved in crashes and the pavement surface is listed as a contributing factor, and early deterioration of the pavement structure due to excessive moisture ingress into the underlying layers." Meanwhile, companies worldwide are devising sophisticated new equipment for carrying out tests on a variety of products, including asphalt, which will be used during road construction.
It is essential that the correct mix is used, and one way to check this is by using specialist equipment to check samples.
For example, the
The company says that it is provided with the innovative 'floating straight edge' on-specimen transducer. This comprises an electrically-powered hydraulic loading system, a beam cradle, an optional environmental chamber, IMACS (Integrated Multi-Axis Control System) data acquisition and control system and Windows operating software.
Troxler launches new gauges
Troxler gauges measure the density and moisture in soil and asphalt in real-time providing critical information on the condition of asphalt as it is being compacted.
The 3430 and 3440 feature direct readout of wet density, dry density and moisture on the large illuminated LCD screen. The keypad is larger and backlit for use in night time situations and the optional GPS capabilities allow the gauge to report on the exact location of each measurement location on completion of each reading.
The lightweight design. Pavetracker Plus features the latest electromagnetic sensing technology and provides the most accurate readings achievable through non-nuclear technology.The test control system is computer based, using sensors on the machine for feedback (load and strain) signals. The beam cradle has been designed to subject an asphalt beam specimen to four-point bending with backlash-free rotation and horizontal translation of all load and reaction points.
Servo motor-driven recirculating ball screws are used to clamp the specimen vertically, and the motors are operated continuously during the test to take up the slack resulting from permanent deformation of the specimen at the clamping surfaces. The clamping force is controlled by regulating the motor current. The electrical supply to the motor drive circuit is provided by the IMACS, while the hydraulic system uses a bottom-loading actuator system with an electro-hydraulic servo-valve, with PID (proportional-integral-derivative) feedback loop control and a run-time adaptive control that adjusts the command signal on the fly during testing.
The pump motor is 230 volts single phase, approximately 2hp, and the pump uses a thermostatically-controlled fan-forced air cooling system to cool the hydraulic oil.
"The PC software is user-friendly, menu-driven and written in Borland Dephi (Windows). In operation, the system gathers the dynamic data from the specimen under test, then displays plots appropriate to each test type and function mode, in real-time on the PC,".
"Non-linear regression data fitting ensures reliable determination of phase and modulus. The software automatically saves test information in binary files, which then provides the offline facilities of reviewing previously run tests through the graphics screens of the system or generation of data files for importing into a spreadsheet package.
For asphalt and bituminous mixtures, the 75-B0008 machine uses the ignition method for rapid and precise determination of the bitumen content in the mix. A sophisticated system, combining combustion with weighing and continuous measurement of weight loss of the mixture, automatically ends the test when binder content is determined.
An integrated system for flexural fatigue tests on bituminous mixture beams, the 77-B3300 beam fatigue apparatus comprises a cradle with pneumatic lateral positioning and clamping and a digital servo-controlled pneumatic actuator built into the base.
Compact system
"The versatile test system fulfills the requirements of ASTM (
Several pre-programmed software applications are available with the compact soil and asphalt test system.
The company says that some of the pre-programmed applications available from it include current test standards for performing indirect tensile creep of asphalt, dynamic modulus, static creep, repeated load, and also resilient modulus of both soil and asphalt.
"For users who wish to develop their own custom testing procedures, Interlaken provides a user-friendly application software called Test Builder. Using graphical icons, users can build their own tests and save them to disk for instant recall." The Interlaken compact soil and asphalt test system includes flexible, fully integrated software for control, data acquisition and real-time monitoring.
UniTest, Interlaken's control system software, features a test wizard to guide the operator through each testing process.
"In addition, a real-time graphic scope provides instant visual feedback of up to six channels of system data. The data is automatically collected and recorded with time stamp information for analysing data," says Interlaken.
Accessories and fixtures available for the system include environmental chambers, indirect tensile fixtures, magnetic-mounted extensometers, linear displacement transducers (LVDTs), and a variety of load cells and triaxial cells.
The company's compact soil and asphalt testing systems test the quality, performance and reliability of soils and pavements for researchers and contractors working in the areas of quality control/quality assurance, research and production.
"The users of Interlaken systems are found at civil engineering departments, consulting and materials testing firms, universities, road pavement construction companies, and pavement materials manufacturing industries," says Interlaken ·
Gilson launches the SG-4
"It uses a precision microprocessor-controlled system (patent pending) to measure water displacement with superior resolution and accuracy. This improved method provides considerably more reliable and repeatable test results than other current methods," says Gilson.
The weight of the dry asphalt specimen is entered with the keypad and the sample is lowered into the measuring chamber. The bulk specific gravity is read directly from the keypad in minutes, saving time and eliminating potential inconsistencies created by subjective drying and other, less precise methods.
"The unit uses no consumable products, allows the user to perform more than twice as many tests in the same time and greatly improves repeatability between operators," claims Gilson.
The SG-4 is self-contained and includes the measuring chamber and the 4" (5.8cm) and 6" (7.6cm) sample loaders required to perform the test. An SGA-49 label printer can be ordered separately to allow immediate documentation of specific gravity test results.
