Test Methods and Specifications

Polymer modified binders (PMBs) are prepared from mixtures of polymers, additives and bitumen selected to achieve their required properties. Some of these binder systems can segregate, leading to variations in measured properties and in some instances significant reductions in desired field performance.

This test method describes a procedure for determining the propensity of components in binders (e.g. polymers) to segregate during prolonged storage at high temperatures. It provides a means by which the storage stability of a binder can be assessed in terms of the segregation of different binder components during hot storage.

The method involves placing a binder sample into an oven at an elevated temperature and, after a prescribed time, measuring the properties (typically softening point) of the top, middle and bottom thirds of the sample. This method is applicable for use on PMBs which contain one polymer type (e.g. styrene‑butadiene‑styrene (SBS) polymer) and hybrid PMBs which contain multiple polymer types (e.g. SBS polymer and crumb rubber).

This test method can also be downloaded as a Word document.