ABSTRACT
The costs of gravel and crushed stone in Egypt rise as existing sources become
exhausted and less suitable supplies have to be exploited. The main objective of this paper is
to study the possibility of using emulsions in sand -bitumen mixes used as base layers in desert
roads. This objective could be achieved through the s election of the best gradation of sands
and optimum emulsion contents. A comprehensive literature review was conducted and the
main findings of this review were used to formulate the res earch plan and testing program.
The experimental investigation included the design of 15 sand-bitumen mixes using five
different sand gradations with three different powder percent ages. The testing program
included testing of Marshall specimens for their d ensity, stability and flow. Air voids and
voids in mineral aggregates were then calculated. Based on the results of the work presented
in this paper, asphalt emulsions could be used successfully in sand -bitumen mixes as a base
course of desert roads. This may reduce costs of construction aggregates and transportation of
construction materials. On the other hand, some sand-bitumen mixes prepared using asphalt
emulsions resulted in high stability values of 695Kg. Mixes like these may even be used as a
surface layer in low-volume roads.