Road surface materials testing

There are now more and more extreme demands placed on asphalt for roads due to increased road traffic and the effects of environmental factors. It wears out or becomes deformed, rough, and brittle. A longer lifespan can only be achieved with extremely high quality, durable asphalts. The manufacture of these is predominantly based on established data for the composition of asphalt, regarding binding materials, grit size distribution and porosity.

European asphalt mixture manufacturers are required to test their mixtures according to the European standard EN12697. Along with static testing processes, it is important to carry out dynamic tests, as the asphalt will be stressed dynamically by moving tires on the road. Zwick has developed a servo-hydraulic testing system for these testing requirements that is equipped with the testing tools and software needed for this kind of testing.

The basis for the asphalt testing system is the newly developed load frame HB 10, which has a hydrostatically stored test actuator with a servo valve and hydraulic accumulator unit built into its upper crosshead. The load cell with acceleration cell is installed on the piston rod of the test actuator.  There is also a temperature chamber with cooling unit for testing at low temperatures. The temperature chamber is mounted on guide rails and can therefore be pushed into testing position in the load frame very quickly.

Features specially developed for asphalt testing systems open up new possibilities for testing:
• Indirect tensile tests (dynamic indirect tensile test) according to DIN EN 12697-24 for the testing of stiffness and durability
• Dynamic indenter tests according to DIN EN 12697-25A for the testing of permanent deformation and creep characteristics
• Triaxial pulsating compressive strength tests according to DIN EN 12697-25B for the testing of permanent deformation and creep characteristics in the prevention of transverse strain
• 4-point flexure tests according to DIN EN 12697-24 for testing the dynamic stiffness under flexure and fatigue resistance

The reliable HydroWin 9610 is used as the measuring and control electronic unit, which can process measurement data at a speed of 10 kHz at a resolution of 19. The testing processes required are carried out using the user-friendly workshop software with dynamic analysis and processing script. After transferring the measurement data in ASCII format to an Excel program, the results are then calculated according to regulation standards.
The Zwick asphalt testing system is suited to testing asphalt for deformation, stiffness and fatigue.

More information about fatigue testing.