Evaluation of pavement distress for asphalt pavement using pavement condition index: case study from adama to awash arba

Abstract

Pavement distress is a common problem for an opening road network and this distress is caused due to overloading of vehicles, poor maintenance, rapid traffic growth and improper design and implementation. This research study focused in Adama to Awash-Arba road section. The main objective of this research work was to evaluate the pavement distress using pavement condition index for the road section from Adama to Awash Arba. In order to achieve the desired objectives, a systematic methodology was performed which include field survey to capture the road surface condition such as type of distress, level of severity and quantity on each 1000metre sample unit and laboratory test was performed for failed and serious pavement condition. The pavement condition survey along the selected road shows that it was affected by different failure type such as alligator cracking, bleeding, block cracking, corrugation, depression, edge cracking, longitudinal and transverse cracking, patching, polished aggregate, potholes, railroad crossing, rutting and swell. The result of the research show that the PCI value range from 8 to 97.1 and this shows that all section of the road have all types of pavement condition rating (Good, Satisfactory, Fair, Very Poor, Poor, Serious and Failed) in which 12.12% good, 9.09% satisfactory, 18.18% fair, 21.21% poor, 18.18% very poor, 18.18% serious and 3.03% was failed. Based on the pavement condition rating, seven soil samples was collected for the failed and serious road section using manual hand auger. Samples were air-dried before taken to laboratory test determination of subgrade soil. The soil samples collected were analyzed based on the geotechnical analysis: Gradation, Atterberg limit, Standard proctor test and California bearing ratio (CBR), analysis has been carried out for failed and serious pavement condition rating for the subgrade soil. For subgrade soil the liquid limit varies from 33.02% -44.48% and Plasticity index from 11.3% - 25.56% According to ERA manual, soils with LL< 50% and PI > 25% are suitable subgrade materials so all station are good. The soils were classified by ASSHTO under the A-6 and A7-6 category which showed that the soils were fair to poor as a sub-grade material. The soaked CBR values of subgrade soil materials are between 7.9% -10.4% so according to ERA manual this quarry site soil are satisfy suitability property of natural subgrade soils. Therefore, from the laboratory test results the subgrade soil was not the cause of pavement failure for failed and serious pavement condition rating. According to the pavement condition survey the road section from Adama to Awash Arba required maintenance and based on this, possible maintenance option had been recommended for pavement distress with respect to level of severity on the pavement condition of the study area in order to sustain the design life of the Pavement.