Dr Elaine Goosen, Stellenbosch University
PAPER
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Abstract
Bituminous material failure manifests distinctively in specific ranges of the binder behaviour spectra. Permanent deformation, and fatigue and non-load-associated cracking, are associated with high, intermediate, and low-temperature behaviour. Additionally, premature oxidation of bitumen in low-stiffness ranges during plant processing may complicate and hinder the quality of in-field asphalt compaction.
Ageing ratios are included in the South African Performance Grade Specification to control ageing in the intermediate stiffness range. In the context of abundantly available performance parameters, transitioning engineering knowledge from penetration-viscosity to performance grades and the increasing prevalence of bitumen importation, this paper investigates whether the ageing rates are consistent over the binder behaviour spectra.
Performance parameters in the distinct behaviour ranges are analysed for neat, laboratory-aged and recovered binders. Ageing and the mechanisms influencing relative susceptibility throughout the behaviour spectra are explored. Modified and unmodified binders are evaluated using Dynamic Shear and Bending Beam Rheometers to develop ageing ratios for DTc, Gvet, wc, Gint, G-R and Tmax,cont. The relative ageing represented by each parameter is examined.
It is observed that ageing over the binder behaviour spectra is influenced by the initial performance grade, source, and type and degree of modification. These trends may assist in selecting suitable binders and premature failure investigations.
Elaine is a Pavement Engineer and Lecturer in Civil Engineering at Stellenbosch University, specialising in Pavement Engineering and Bitumen Rheology. Elaine completed her BEng in Civil Engineering in 2011 and her PhD in 2021, with the award of various bursaries and scholarships testifying to her talent and dedication.
She spent a semester at Technische Universiteit in Delft, Netherlands, as an Exchange Student in Civil Engineering, and worked for WorleyParsons RSA as a Graduate Civil Engineer and then Assistant Resident Engineer in Roads and Stormwater.
Elaine is establishing her research career focusing on sustainable pavement materials and applying numerical models and machine learning to materials datasets.
