Evaluation of the Distresses and the Performance of Asphalt Pavement Based on Pavement Condition Index and Engineering Properties of Layers: A Case Study of Alaba-Sodo Road

Abstract

Generally, complex distress is the result for pavement deterioration like pavement cracking, deformation of the pavement structure, and disintegration of materials. This deterioration may begin as soon as the road is open to traffic. In Ethiopia, pavement distress is the main problem of roads affecting the socio-economic development of the nation. Alaba-Sodo road, which is located in SNNPRS, is one of the roads affected by distresses. The main objective of this study is to evaluate the distresses and the performance of Alaba-Sodo asphalt pavement based on pavement condition index and engineering properties of the layers. Along the Alaba-Sodo road, 60 sample units of defective locations were selected using systematic random sampling technique. For the selected samples, the PCI values were used to evaluate the performance of the road. In addition, Laboratory experiments were conducted to check the compliance of the engineering property of the pavement materials with ERA specifications. Based on the PCI values, four sub-base, base and sub-grade samples were taken for laboratory experiment. Out of these, 2 were taken from location which were in a very poor condition, 1 from poor condition and 1 from where there is no distress. The major tests such as CBR test, Compaction Test, Atterberge limit test, and Sieve Analysis were conducted for each sample. The thicknesses of the layers in these points were also measured so as to check whether or not they are as per the design. From the pavement condition survey, it was found that the PCI values range from 25- 79. Among the 60 sample units, 11.67% were very good, 16.67% were good, 43.33% were fair, 26.67% were poor, and 1.67% was very poor. Except for the sub-base, all of the layers satisfy the ERA specification requirements. Moreover, the thicknesses were found to be as per the design. In conclusion, most of the sections of the road are in fair and poor conditions and the cause of the premature distress of the road can be the poor quality of sub-base material. Therefore, to avoid further destruction of the road, more detailed tests on the structural capacity of the pavement should be made and based on the result of those tests, remedial measures should be made urgently.