Four Point Bending Machine – A low cost, accurate beam testing system which facilitates the rapid throughput of modulus and fatigue tests

Bending tests are widely used for measuring the stiffness modulus and assessing the fatigue resistance of asphaltic paving materials.The specimen is a prismatic beam which is subjected to sinusoidal loading in either the controlled strain or controlled stress modes.

The SA4PT uses advanced servo pneumatic technology and a high-speed digital data acquisition and control system together with user-friendly software. During testing both graphical and tabular data are displayed on screen and test data is stored to disc in Microsoft Excel™ compatible format. The clamps are at 118.5mm centres (the distance between the outer clamps is 335.6mm (14 inches) according to AASHTO specifications² but the height and width of the beam can be varied).

² Tests on beams containing aggregates greater than 20mm are not strictly in accordance with annex D of EN 12697-24 which states that this non-compliance should be explicitly mentioned in the test report.

Standards

  • EN 12697-24 Annex D
  • EN 12697-26 Annex B
  • ASTM D7460
  • AASHTO T321

Key Features

  • Frequency range 0.1 to 30Hz¹
  • Low cost pneumatic stand alone four point bending machine
  • Low-friction actuator and high performance ceramic spool servo-valve
  • On-specimen measurement system removes errors due to frame flexure
  • Designed for AASHTO beam sizes
  • Sinusoidal controlled strain or controlled stress fatigue test modes
  • Constant torque motorized specimen clamping to eliminate errors due to localised beam indentation
  • Self-contained loading system
  • User friendly software for determination of fatigue resistance and stiffness modulus
  • Capable of performing healing, modulus, fatigue multi-stage testing and camera triggering
  • Supplied with traceable certificate of calibration

Key Uses

  • Mix design
  • End product specification
  • Assessment of new materials

Software – DIMENSION

  • User friendly, intuitive and reliable Windows™ software developed using LabVIEW™
  • Specifically written to meet EN 12697-24 Annex D and EN 12697-26 Annex B
  • The user interface can be translated into the user’s preferred language – please enquire
  • Stored test data can be analysed and compared with other test data utilising a spreadsheet package
  • Utilities are included for curve fitting of acquired data; testing of system’s inputs and outputs; phase correction and a transducer database for storing calibration factors

Data Acquisition – cDAC

  • Measurement of up to 32 transducers
  • Wave Types: Haversine , Pulse, Square, Triangle, Constant, Ramped, Rest Periods