Browsing by Author "Burger, A. F."

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    Rheology of polymer modified binders : a comparative study of three binders and three binder/filler systems
    (Stellenbosch : Stellenbosch University, 2001) Burger, A. F.; Jenkins, K. J.; Van de Ven, M. F. C.; Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering.
    ENGLISH ABSTRACT: The use of polymer modified binders have increased drastically over the past twenty years. It is generally accepted that current empirical specification tests do not adequately characterise the improvement in binder properties when bitumen is modified with polymers. At the University of Stellenbosch, a programme was initiated to relate binder properties to asphalt mix performance. This study forms part of that programme. This study focuses on three binders and is an attempt to characterise binder properties fundamentally. The binders that were tested are: • 60/70 penetration grade bitumen • SBS modified 60/70 bitumen • Bitumen-Rubber Two rheometers were used to characterise the binder properties: • Sliding Plate Rheometer (SPR) • Dynamic Shear Rheometer (DSR) The Sliding Plate Rheometer was modified to allow testing at elevated temperatures. The modification is described in this thesis. Three types of testing were used to test the binders: • Creep tests (SPR and DSR) • Dynamic tests (Strain and Frequency Sweeps - DSR) • Flow tests (high temperature viscosity tests - DSR) The results of the tests were used to characterise differences between the binders. Shear susceptibility lines were plotted and viscosities calculated from the creep test results; Master Curves and Black Diagrams were plotted from frequency sweep results; flow test results were used to characterise high temperature behaviour. A further development in the asphalt industry is the move towards the development of performance based specifications. A programme has been initiated in this regard and this study forms part of the programme. As a step towards the development of performance based specifications filler was included in this study. BinderlFiller systems were subjected to the same test programme the binders were, to characterise the influence on binder properties of filler addition. Some of the conclusions that were drawn at the end of the study are: • Polymer modification improves binder properties related to rutting. • Filler addition does not affect binder properties negatively. • Shear rate is very important during production of asphalt mixes and construction of asphalt layers containing polymer modified binders.