Conventional bitumen testing

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Needle penetration (DIN EN 1426)

Mode of operation
  • Needle is pressed into a prepared bitumen specimen for 5 s with a force of 100 N at 25 °C
  • As a result, the penetration depth of the needle is measured in [1/10 mm].
Interpretation and use
  • The deeper the needle penetrates into the sample, the lower is the viscosity of the binder.
  • Test result is used for the classification of bitumen

Softening point ring and ball (DIN EN 1427)

Mode of operation
  • A steel ball (3.50 g) is placed on a bitumen sample poured into a shouldered ring and heated in a water bath at a controlled rate of 5°C/min. The steel ball is then placed in the water bath.
  • Due to the reduced viscosity with temperature increase, the ball sinks into the bitumen sample and a "bitumen bag is formed".
  • The softening point is the temperature at which the ball has dropped 25 mm in the bitumen envelope
    Interpretation and use
    • The softening point is an empirical parameter that can be used to indicate the upper plasticity limit.
    • A high softening point is an indication of high binder viscosity (hard bitumen).
    • The softening point in combination with needle penetration is used to classify polymer modified bitumen (PmB).

      Breaking point according to Fraass (DIN EN 12593)

      • Repeated bending and relief of a bitumen film cast on a metal platelet
      • Continuous temperature reduction (1 °C per min).
      • The temperature at which a crack in the bitumen film becomes visible is given as "Breaking point according to Fraass" in [°C] as test result
          Interpretation and use
          • Empirical characteristic value describing the lower plasticity limit
          • low breaking points indicate good low-temperature flexibility (crack resistance)

            Ductility (DIN 52013) and elastic recovery (DIN EN 13398)

            How it works
            • Ductility:
              A bone-shaped bitumen sample is pulled apart in a water bath to a multiple of its original length.
              The pull-out distance until the bitumen thread breaks is specified as ductility in [cm].
            • Elastic recovery:
              At an extension length of 20 cm, the bitumen thread is cut with scissors
              After 30 minutes, the distance between the free thread ends is measured.
              The thread end distance is divided by the extension length of 20 cm and given as the test result in [%].
                Interpretation and use
                • Ductility:
                  High ductility indicates high binder flexibility.
                  Low ductility indicates brittleness.
                • Elatic reserve:
                  Serves as a characterization feature for modified binders.
                  High el. reserves indicate actively active long-chain elastomers in the bitumen.