Effect of using granular volcanic ash on the mechanical properties of Hot mix asphalt

Abstract

Granular volcanic ash material is spread over considerable parts of Yemen including urban and
suburban areas. Due to the inferior properties of this material, in its natural state, it can not be used as a
foundation either for roads or buildings. It is common practice, when faced with such material, to
replace it with superior filling material. Excavated volcanic ash is disposed of by transporting it to landfill
sites. Such solution is expensive and the amount of transported materials increases with time which
necessitates the allocation of new sites. Due to the massive amount of transported material, the problem in
some urban areas is becoming an environmental issue. It is clear that improving the properties of such
materials for engineering purposes or finding possible uses for it in construction industry is needed.
The available literature indicates that the use of volcanic ash in construction industry is very limited
and therefore, this study can be considered a pioneer study in this field in Yemen.
The main objective of the study is to investigate the effect of using volcanic ash on the mechanical
properties of Hot Mix Asphalt (HMA).
The effects of using granular volcanic ash material, as a partial replacement of conventional aggregate,
on the properties of HMA were studied. Four replacement levels i.e. 0%, 10%, 20% and 30%, of total
weight of dry aggregate, were used. The 0% volcanic ash content mix was used as the reference mix.
Experimental results showed that partial replacement of basalt aggregates by granular volcanic ash is technically feasible. Results showed that, for volcanic ash percentages up to 20%, all mechanical properties of HMA were within Marshall Mix Design Criteria. This includes stability, flow, voids in mineral aggregate VMA and voids filled with asphalt VFA.
10% replacement of the basalt aggregate by volcanic ash aggregate was found to be the best
replacement percentage that produced asphalt concrete mixes with optimal stripping resistance, stability
and flow.