Influence of Microstructural Behavior on Multiple Stress Creep Recovery (MSCR) in Modified Bitumen

Construction of a durable bituminous pavements requires high quality materials such as e.g. polymer modified bitumen (PMB) with extended viscoelastic properties. The main objective of this paper is to analyse the influence of microstructure of PMB on their high temperature viscoelastic properties and to assess appropriate modifier content. The multiple stress creep recovery (MSCR) procedure tests were conducted to evaluate viscoelastic properties together with fluorescent microscopy used to examine the microstructure of binders.Based on a conventional tests (penetration, softening point, elastic recovery and Fraass breaking point) as well as recovery and non-recoverable creep compliance obtained from MSCR test, amount of an appropriate modifier content was analysed. It was concluded, that although bituminous binders complies with European specification requirements, they are significantly different in terms of their morphology and rheological properties due to the dispersed polymer phase and polymer content. It was found that PMBs within the same hardness group exhibit different high temperature properties. Correlation between polymer phase area and empirical curve from MSCR test for asses proper polymer content was established.