There is a demand for new methods to test polymer-modified bituminous binding materials, because the standard methods for testing them provide no information about their dynamic properties. This article describes two new methods for measuring bitumen ductility and the Fraass breaking point in ways suitable for modern bituminous materials. The Fraass breaking point of bitumen is measured by repeated bending of a steel spring plaque with a bitumen coating on one side. The temperature is reduced step by step while the plaque is regularly bent. However, the usual method of measurement by high voltage indication does not work when testing elastic polymer-modified bitumen. It was found that the micro-cracking observed in this case could be measured and recorded dynamically in a force-time diagram. The method of elastic recovery for measuring the ductility of bitumen produces more significant results, especially for polymer-modified bitumen. Ductility tests become more informative when they use sensors to measure force per time. The Petrotest DDA 2 automatic tensile stress ductility meter measures elastic recovery automatically, and the Petrotest DDA Z ductility meter determines elastic recovery without cutting. Both testers offer new ways to inspect and record the elasticity and plasticity of new bitumen.
Samenvatting