Abstract:
Pavement distresses are one of the major problems in developing countries and the wide
range of problems that occurred on sealed road. While the problems can be occurred on
going or after construction of the road has been finished. Broadly speaking, flexible
pavement distresses fall into different categories:Cracking,Patching. Surface
Deformation, Surface Defects, Potholes and Miscellaneous Distresses. This research study
carried out at Ilu-Ababor zone situated within the Western Ethiopia. This place is found in
Western Oromia region. Dembi-Bedele highway currently shows pothole, patching, rutting,
polished aggregate, cracks and shoving types of distress.
The scope of the research is to determine the type, extent and severity of the pavement
distresses and to measure the structural strength of the existing road pavements at distressed
sections.
Destructive test method (DCP and Test Pits) were used in the field and laboratory testing
tools for the data analysis. Basically, six different data were collected by DCP test and three
test pits have been taken. Besides, DCP field data collected were analysed by UK DCP, 3.1
software. From these results,CBR value, pavement layers thickness and structural strength
of the pavement were known. Purposive sampling techniques used for DCP test and Test
Pits at both distressed and normal section.
Base on the DCP data analysis, thickness ofsurface,base course sub base sub grade layers
decreased by 25mm, 31mm, 95mm respectively on (chainage 17+870).Additionally, the CBR
values of base course, sub base and sub grade are 78%, 44% and 39% respectivel y. These
results are less than the standard.Besides, at (chainage 25+100) the thickness of pavement
surface, base course, sub base and sub grade layers decreased by 10mm, 18mm, 104mm and
47mm respectively.When compared with previous design. The CBR values are 62%, 27% and
21% for base course, sub abse and sub grade respectively.
