Browsing by Author "Hizbawi, Sisay"

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    Influence of Mineral Fillers on Short Term Ageing Characteristics of Asphalt Mastics
    (Addis Ababa University, 2022-02) Hizbawi, Sisay; Abubaker, Ahmed (PhD)
    Asphalt pavements’ deterioration due to asphalt binder ageing has been a subject of many researches. Different aspects of ageing, its causes and prevention mechanisms were the main focus in this researches and asphalt mixtures, mastics and neat binders have been in use for these purposes. Among these material mixtures, asphalt mastics were found advantageous for they resemble asphalt mixtures better than neat binders and relatively cost less during production than asphalt mixtures. One way to reduce effect of ageing with mastics is to use appropriate mineral fillers with chemical properties to reduce chemical products of ageing or have physically capability to adsorb the molecules formed during ageing. In order to address this issue in more feasible way, this paper presents experimental tests conducted to investigate the effect of using unconventional and abundant filler materials (OPC, PPC, red brick powder and wood ash) as a substitute to a conventional (limestone) filler on the industry to lessen the effect of short-term ageing. Chemical, microscopic, mechanical and rheological tests are conducted on a 60/70 bitumen, the conventional and unconventional fillers as well as on mastics produced from the combination of bitumen and different filler proportions. The results are presented in terms of FTIR spectrums, microscopic images and complex shear modulus (G*) master curves. Consequently, the results suggest that all the fillers have a mitigating effect towards short-term ageing as the offsets in master curves of aged and unaged mastics are less significant than the neat binder. Furthermore, some of the fillers (red brick powder in an excellent way, OPC and PPC in a medium manner) have the desired characteristics to effectively replace the conventional filler used as reference while wood ash filler has relatively the worst characteristics to serve as a replacement for limestone filler.