Abstract
Flexible pavement roads in Ethiopia often deteriorate in different ways, because of the harsh climatic conditions, lack of proper design and quality control, sudden increasing of traffic due to the construction of different industries, high loads and inadequate assessment for identifying causes of deteriorate before carrying out Maintenance and Rehabilitation. A possible remedial measures had been organized for every observed failure or deterioration to obtain normal pavement condition of the study area. An investigation was made by using laboratory and field test to determine the adequacy of the underlain material to serve as a subgrade, sub base course and base course for road construction based on project specifications and Ethiopian Road Authority (ERA) Specification. The investigation covered field tests to determine the in-situ condition of the road materials while laboratory tests on representative samples were extracted from site to determine the engineering properties of soil materials and to compare test results with the existing conditions of pavement layers. From the field tests and laboratory tests carried out, it is observed that the causes of flexible pavement deterioration of this road section are mainly due to the inadequacy of existing thickness of the base layer for the current traffic loading, overloading, engineering properties of the pavement layers material, poor method of construction, poor design quality and lack of side drainage. To reduce these causes, use boulder rocks at subbase course, reconstruction the base and providing proper drainage for the deteriorated sections must be required to reduce more damage of the flexible pavement the road section. Raveling, pumping, potholes, edge cracking and rutting are the most dominant type of deteriorations constituting more than 27% of the deterioration densities along Bako-Gedo road section.
Highlights
A road pavement is a structure of superimposed layers of selected and processed materials that are placed on the basement soil or subgrade
1) The laboratory and field test results that had been obtained on the pavement materials used for the construction of the road section under the research discussed and compared with the requirements of the standard specification, which shows poor results at section (1) and relatively good results at section (2) and
(3). 2) The investigation have revealed that different type and degree of deteriorations observed on the pavement surface. a High deteriorations observed at section (1), type of deterioration are observed at this section. b Medium deterioration is observed at section (2), type of deterioration are observed at this section. c Relatively low deterioration is noticed at section (3), (Edge cracking and Raveling) types of deterioration are observed at this section
Summary
A road pavement is a structure of superimposed layers of selected and processed materials that are placed on the basement soil or subgrade. A flexible pavement is one of the largest infrastructure components in civil construction works and complex system that involves multiple layers of different materials subjected to various combinations of irregular traffic loadings and varying environmental conditions. It provides the road-user a smooth, quiet and skid-resistant riding surface, maximizes tire contact by providing more traction, and saves wear and tear on vehicles. Economical and most long-lasting roads that can be built very quickly thereby reducing costs due to traffic delays and save the traveling time
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