Polymer modified binders (PMBs)—which, according to EN 14023, is divided on the basis of penetration at 25°C and softening point (ring and ball)—have also been used.
When a modified binder is being used to enhance a particular property of an SMA mixture, with no reference to binder features (e. g., resistance to fatigue), some additional tests should be performed to confirm the desired effectiveness of a given binder. These tests should be conducted using methods described in the standard EN 12697. Using the results of previous tests is permissible. The origins of this clause of the SMA standard (EN 13108-5) are in the structure of the standard concerning PMB (EN 14023), which has a combination of classes enabling the description of basic requirements for PMB. There is no direct correlation between these requirements and the functional properties of asphalt mixes. Consequently, the effectiveness of a selected PMB in the asphalt mixture should be checked.
