Abstract:
Since material properties play a significant role to determine the performance of pavement layers, assessing the performance of those materials quality after opening to the traffic allows the road to achieve the desired service for the expected traffic and also it helps to propose proper counter measures for the detected problems. In Ethiopia, now a days, pavement distress is the main problem of roads affecting its intended purposes. The research study is undertaken at Alaba-Sodo road, which is located in SNNPRS, is one of the roads affected by distresses. The performance of pavement material was assessed through condition survey and laboratory tests and their effect on the distresses was also indicated. This helps the concerned bodies to go for the remedial measures.
Among the total sample units of 199 along the selected road sections, 71 sample units were selected by using systematic random sampling technique. For those selected sample units PCI values were determined in order to know the stations for sample collection for laboratory tests. Based on the PCI values, eight sample locations were identified out of these six locations were selected from severely distressed and two locations were selected from good sections. From eight identified sample locations three samples were taken from each layers of sub-grade, sub-base and base course. Therefore, total of 24 material samples were taken for the laboratory tests. The major tests such as CBR test, Compaction Test, Atterberg limit test, Sieve Analysis were conducted for the above mentioned three layers and ACV, AIV, LAA and Flakiness Index were conducted only for base course material to check performance of the pavement materials.
Out of the surveyed 71 sample units, 1.41% is excellent, 5.63 is very good, 14.08% is good, 23.94% is fair, 28.17% is poor, 21.13% is very poor and 5.63 is failed. The overall laboratory test results shows that the distresses that are frequently observed on the road surface were significantly influenced by subbase and base course materials. The subbase and base course materials don’t satisfy the gradation limit and CBR value specified by ERA, AASHTO specification. But the subgrade material satisfies the requirements of ERA specification. Therefore, in order to avoid further damage of the road, more detailed tests on the structural capacity of the pavement and other distress cause investigation should be made and based on the result of those tests, remedial measures should be made urgently.
