Rheology of polymer modified binders : a comparative study of three binders and three binder/filler systems

Burger, A. F. (2001)

Thesis (MEng)--University of Stellenbosch, 2001.

Thesis

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.

AFRIKAANSE OPSOMMING: Die gebruik van polimeer gemodifiseerde bitumen het drasties toegeneem oor die afgelope twintig jaar. Dit word algemeen aanvaar dat die huidige empiriese spesifikasie toetse nie die verbetering in bindmiddeleienskappe van polimeer modifisering aanvaarbaar karakteriseer nie. 'n Program is geïnisieer by die Universiteit van Stellenbosch om 'n verband te vind tussen bindmiddeleienskappe en asfaltmengseleienskappe. Hierdie studie vorm deel van die program. Hierdie werk fokus op drie bindmiddels en is 'n poging om die bindmiddeleienskappe fundamenteel te karakteriseer. Die bindmiddels wat gebruik is in hierdie werk, is: • 60/70 penetrasiegraad bitumen • SBS gemodifiseerde 60/70 bittimen • Bitumen-Rubber Twee reometers is gebruik om bindmiddeleienskappe te karakteriseer: • Glyplaat Reometer (SPR) • Dinamiese SkuifReometer (DSR) Die glyplaat reometer is aangepas om toetse by hoër temperature te doen en die aanpassing wat gemaak is word in die tesis beskryf. Drie tipes toetse is uitgevoer om die bindmiddels mee te toets: • Kruiptoetse (SPR en DSR) • Dinamiese toetse (DSR) • Vloei toetse (DSR) Die resultate van die toetse is gebruik om die verksille tussen die bindmiddels te kwalifiseer. Verskillende grafieke en figure is getrek van die resultate om die onderskeie bindmiddels te karakteriseer. Die beweging weg van empmese spesifikasies na werkverrigting gebaseerde spesifikasies in die asfalt industrie is 'n verder nuwe ontwikkeling. 'n Program is geïnisïeer ten opsigte hiervan en hierdie werk vorm deel van die program. As 'n stap in die ontwikkeling van die werkverrigting gebaseerde spesifikasies is 'n vuIler ingesluit in die toetsprogram. Bindmiddel/vuIler stelsels is onderwerp aan dieselfde toetse waaraan die bindmiddels onderwerp is om die invloed van die vuIler op die bindmiddels te karakteriseer. Sommige van die gevolgtrekkings waartoe gekom is aan die einde van die tesis, is: • Polimeer modifisering verbeter bindmiddeleienskappe met betrekking tot wielsporing. • Die toevoeging van vuIler affekteer nie die bindmiddeleienskappe negatiefnie. • Die vervormingstempo is van groot belang wanneer asfaltmengsels gemeng en lae gebou word van mengsels wat polimeer gemodifiseerde bitumen bevat.

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