Eurobitume’s mission is to promote the efficient, economic, effective and safe use of bitumen. Harmonised standards are the basis for defining the consistent and effective specifications for supply of bitumen across Europe. Eurobitume contributes to the development of standards and test methods by participation in CEN working groups to ensure that bitumen specifications are fit for purpose. Various fundamental test methods are used for the technical classification and assessment of the different bitumen types which, in the first instance, determine the consistency of the bitumen in different temperature ranges.
The main characteristics of Bituminous binders are tested using traditional test methods, which have been used for many years. These test methods were developed and validated for non-modified bitumen. For practical reasons, these test methods have also been adopted for polymer modified binders. However, new, fundamental test methods might be useful to better describe the properties of modified binders. These new test methods have been reviewed by Eurobitume and are recommended for incorporation into specifications when they are revised. Unmodified binders can be described reliably and their use behaviour assessed using traditional test methods.
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Individual test methods
Softening point – Ring and Ball method (EN 1427)
This method, under European standard EN 1427, serves to test the behaviour of bitumen at elevated service temperatures. The temperature is determined at which a layer of bitumen, in a brass ring, experiences a certain deformation under the weight of a steel ball as the temperature rises. This test method has been used for more than one hundred years.
A test method that has been used for decades, which is now described in EN 1426. Needle penetration is determined by the depth, measured in 1/10 mm, to which a 100 g needle penetrates in 5 seconds into the bitumen at a temperature of 25 °C. It serves to test the behaviour of bitumen at intermediate service temperatures. This test method is suitable for all types of bitumen.
Fraass breaking point
The determination of the Fraass breaking point is described in the test standard EN 12593. It describes the transition of the binder from a flexible to a brittle condition and provides the temperature at which a thin bitumen layer on a steel sheet cracks during uniform cooling when it is bent under defined conditions. The test indicates the behaviour of the bitumen at low service temperatures.
The test for elastic recovery is applicable to binders modified with elastomers, and serves to demonstrate the modification of the binder. The sample is stretched at a fixed temperature and speed to a maximum of 20 cm and then severed. After a prescribed period of time, the degree of elastic recovery is determined relative to the original length.
The further development of the well-known ductility test serves to determine the cohesive characteristics of a binder, the test is used in the standard for polymer-modified bitumen. A sample is stretched at a fixed temperature and speed and the necessary tensile force is measured and recorded continuously. The data are used, among other things, to calculate the deformation energy, the maximum tensile force or the stretch length of the sample until breakage. Further options for interpretation of the data are currently being researched and discussed.
Bending Beam Rheometer
The Bending Beam Rheometer (BBR) is a testing device to address the behaviour of bitumen at low service temperatures and is described in the test standard EN 14771. The sample is placed under a constant force in a liquid bath at low temperature for a fixed duration. The creep stiffness of the sample is calculated from the recorded data of the flexural stress and strain. The test provides information on the behaviour of the binder at low temperatures.