Influence of Mineral Fillers on Short Term Ageing Characteristics of Asphalt Mastics
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Date
2022-02
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Addis Ababa University
Abstract
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.
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Keywords
Asphalt Mastics, Mineral Fillers