: This master thesis purports to address the effects of different filler types in asphalt mastics and
relate the differences to asphalt mixture properties and volumetric composition. Due to variations in
properties for different filler types, e.g. particle size, density, mineral composition, Rigden voids, specific
surface area and binder interaction, the same filler amount by weight yields variations in occupied volume
and bind different amounts of bitumen. Uncontrolled variations of the filler fraction can cause binder
drainage as a result of insufficient reinforcement or a dry mixture with unsatisfactory coating of the
aggregates. The literature review focused on outlining characteristics and effects of different fillers and
mastic composition and to relate variations in mixture performance to filler types and the ratio of filler to
binder. An experimental laboratory research has been conducted to evaluate the effects of using different
filler types. Mixtures with limestone and hydrated lime have been compared to mixtures with natural
sieved dust from Vassfjell and Steinkjer aggregates on the 0.063 mm sieve. The results showed that the
Rigden void content in the filler has an effect on the compacted asphalt mixture. Higher Rigden void
content yields higher indirect tensile strength and a tendency to lower the abrasion resistance. The
outcome from cyclic compression test was scattered, and there were too few data point to give any
adequate conclusion. The tests showed that the F/A-ratio by mass or volume had less influence on the
mixture performance. The air void content and the degree of compaction of the specimen greatly
influenced the outcome, which coincide with results in the literature. The air void content was related to
the Rigden void content, and in the literature it was found that higher Rigden void content in the filler
gave higher air void content in the compacted specimens. Furthermore, increasing Rigden void content
tended to increase the effective volumetric filler particle concentration in the mastics.