Technical Feasibility of Water Bound Macadam for Unpaved Roads: A Case Study in Dire Dawa, Ethiopia.

Abstract

It is a major challenge for developing country like Ethiopia to provide and maintain all roads of the country on a sustainable basis with the limited resources. For better utilization of limited resources, it requires the usage of affordable and appropriate low-cost road construction techniques for unpaved roads. One of the affordable and appropriate low-cost road construction techniques for unpaved roads is water bound macadam as surfacing materials, which has been widely used in many developing countries. The objective of this research was to investigate technical feasibility of Dire Dawa water bound macadam surfacing material for unpaved roads. The research started with verification of availability of water bound macadam surfacing material and focused on investigation of physical and engineering properties by conducting laboratory tests and the conclusions and recommendations were given by comparing the laboratory test results with international standard manuals. This research paper highlight on availability of water bound macadam surfacing materials in the study area and presented findings of laboratory test results of physical properties of coarse aggregate ( grain size analysis test result nominal size of 50 mm and flakiness index test result of less than 20%), the engineering property of coarse aggregate (los angels abrasion test result less than 30%), and physical properties of natural river sand (grain size analysis more than 98% passing sieve size 5.6 mm, less than 1% passing 75microns, LL less than 20% and PI less than 6%). The research paper finally compared the test results to international standard manuals and concluded that the Dire Dawa water bound macadam surfacing materials has the best quality of physical and engineering properties that feasible to be used as surfacing material for unpaved roads. The research result report is submitted to Department of civil engineering, Jimma Institute of Technology and published on the Jimma institute of Technology journal.