Abstract:
Flexible pavements constructed for heavy duty vehicles are composed of asphaltic
layers, base course, Sub-base and sub grade foundation. Base course serves as the
principal structural of flexible pavement and distributes the imposed wheel load to the
pavement foundation (sub grade). The quality of the base layer is an important impact
on the lifetime of a pavement, particularly for flexible pavement. Pavement distress,
will be reduced if the base layer is made properly using acceptable aggregates that
maintain their integrity throughout the lifetime. General objective of this research was
Investigation on the suitability of different quarry site aggregate for base course
aggregate of asphalt pavement construction in case of Jimma city.
The study was achieved by conducting physical (Gradation, Specific Gravity & Water
Absorption and shape) and mechanical properties (Aggregate Crushing Value,
Aggregate Impact Value and Los Angeles Abrasion Value) laboratory tests which were
started visiting quarry sites aggregate production and samples was extracted and
brought according to AASHTO T-2 sampling procedure from five different quarry sites
to Jimma Institution of Technology, Highway Engineering laboratory where qualities
of aggregates investigated and evaluated according to ERA, AASHTO, ASTM and BS.
The results from this study have shown that, Both Jemila and Welda Mikrbete Quarry
Site Base Course Crushed Aggregate were fulfilled gradation requirement. In term of
Aggregate Crushing Value, Aggregate Impact Value and Los Angeles Abrasion Value
all are within the requirement. Specific gravity and Water absorption of all quarry site
aggregate were in the same range from 2.76 to 2.81 and 1.30% to 1.55% respectively,
all are acceptable. Flakiness and Elongation Index was achieved by all quarry site
which from 17.84% to 23.91% and from 26.88% to 29.68% for FI and EI respectively.
Based on the findings in this thesis concluded that, the results of overall aggregate
physical and mechanical properties pointed out that all Five quarry site crushed
aggregates are within the standard specification limits and it is suitable for use in base
course aggregate of asphalt pavement construction except three quarry site gradation
requirements is failed
