Investigation on the suitability of different quarry site crushed aggregate for base course aggregate of asphalt pavement construction in case of Jimma city

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