Abstract:
Road network development in Ethiopia is booming, radiating from Addis Ababa towards North-
South directions, and East-West directions, due to the good economic growth of the country.
However, there are challenges always facing by the pavement designers, and materials engineers
for every road project, specifically the unpaved roads in Goffa Zone. It was because, most parts of
the existing unpaved road sections within the study area are heavily damaged, and lack of proper
maintenance. The source of good quality of sub-base course materials limited and becoming
depleted. It is for this reason that the research study focused on the investigation of the effects of
mechanically stabilized graded assorted coarse-grained soils. Disturbed and undisturbed samples
from different quarry sites were considered and tested in the laboratory. Laboratory test for each
location performed, and the results served as control values of the engineering properties of natural
soils. The Disturbed samples tested for Gradation, Atterberg's Liquid Limit Tests, and
Compaction, while, the undisturbed sample tested for the CBR strength, using ASTM manual. The
results of the assorted materials for the sub-base course was analyzed and compared with the
AASHTO and ERA Standard Specifications.
