http://www.press.ierek.com ISSN (Print: 2537-0154, online: 2537-0162) International Journal on: The Academic Research Community Publication DOI: 10.21625/archive.v2i4.385 Utilization of Saline Water on the Mechanical Properties for Unbounded Granular Materials Sherif Adel El Sharkawy 1 1 Lecturer of Highway engineering, dept. of civil engineering, Faculty of engineering, Canadian International College, Cairo, Egypt Abstract It is well-known that three quarters of the world contain saline water. The saline water contains amounts of salt dissolved in water to a concentration of parts in per millions (ppm) includes sodium chloride, Sodium sulfate and magnesium sulfate. Compaction of Base coarse layer is usually done by water which is considered tap water. Cites near shores often need coastal roads to act as service roads parallel to shore lines. For this matter, the use of saline water in compaction is considered a main objective in this situation due to the decrease in transportation cost of Tap water used in hauling and compaction of base coarse layer. This research studies the effect of saline water on the mechanical properties of the unbounded granular material used in base coarse layer. The study compares the results between the use of saline water and standard tap water by subjecting both samples to different lab tests such as California baring ratio (CBR) and modified proctor. The results showed that saline water could be used successfully in the operation of constructing base coarse layer with good results concerning the amount of absorbed water content and maximum dry density of the base coarse layer which will result in good compaction. In addition, the CBR test results showed high evaluation of strength for samples contained saline water. The study used Dolomite material for base coarse layer from Jabal Ataqa as one of the most used aggregate types in EGYPT through construction. © 2019 The Authors. Published by IEREK press. This is an open access article under the CC BY license (https://creativecommons.org/licenses/by/4.0/). Keywords Saline water; CBR test; modified proctor test; base coarse layer; water content; maximum dry density. 1. Introduction The main function of a base coarse layer in a flexible pavement is to provide sufficient cover over the subgrade, to decrease the stresses and strains induced by traffic loading so that subgrade shear failure does not occur and does not densify significantly, In addition, to a loss of shape for the pavement surface. To perform sufficiently, the base coarse must have a number of physical and mechanical properties such as Stability, durability, impermeability and workability to ensure adequate strength and stiffness under the applied traffic loads and the strength is maintained during its designed service life. To be suitable for use as base coarse material, gravel must be capable of devel- oping an adequate bond between the bituminous surfacing and the base course, which is enhanced by a degree of penetration of the first bituminous application into the base course surface. On the other hand, it is well known that saline water affect the road infra-structure negatively. The addition of salt pg. 369