Assessment of Impacts of Environmental Factors (Temperature and Moisture) on the Performance of Flexible Pavement: The Case of Tarcha- Omo River Highway

Abstract

The structural behavior of pavements can be affected by seasonal variation in environmental factors such as temperature and moisture content. In Ethiopia the design, construction and maintenance process of roads mostly give attention to structural thickness of pavement layers, on which the designers and authoring focus on expected future traffic. However it is critical to admit in practical the variation of pavement material properties due to seasonal environmental changes, especially the temperature and moisture. This study focused on assessment of the impacts of environmental factors(temperature and moisture) on performance of flexible pavement in generally and particularly on Tarcha - Omo River highway, hence doing this study, the objectives were: to investigate the impact of temperature on the performance of selected highway, analyze the impact of moisture on the performance of pavement through laboratory based investigation and to examine the efficiency of the drainage system in removing excess water from the pavement structure of selected highway by collecting all primary data from the project site and secondary from, standard specification, Ethiopian roads authority, Omo River-Tarcha road upgrading project. An assessment was done by using both field observation and laboratory tests to characterize materials toward the factors. The field observation was made to investigate the condition of drainage system in removing water from pavement and surrounding. The sample of base course, sub base and sub grade were collected from three different sampling stations and laboratory tests were conducted and finally compared with standards to check the moisture sensitivity of materials. NMC, Compaction, Particle size distribution, CBR and Atterberg’s Limit were tests conducted. Statistical Microsoft Excel 2007 software was employed to analyze the data. The assessment showed that temperature and moisture has considerable impact on performance of flexible pavement and the pavement failed due to moisture variation on pavement base, sub base and subgrade, due to, inadequate drainage facility, lack of effective protection work and excessive water in the sub grade in first section and temperature in second section of study. Therefore Standard of construction and design should be improved. More research should be carried out on the engineering geo techniques of study road