LAUSR

The present paper focuses on the effect of the addition of dune sand on the physical and mechanical properties of the tuff. The percentage of sand added to tuff ranged between 0 and 100%. The geotechnical characteristics of sand and tuff as well as those of their different mixtures were first determined. Then, a series of mechanical tests (unconfined compressive strength UCS and triaxial shear test) were performed on compacted samples at modified proctor optimum (MPO). The results showed that the tuff–dune sand mixtures are denser than the basic materials with lower optimum water content at MPO. It was noticeable that the plasticity index decreased with the increasing percentage of sand added, due to the contribution of the fine particles of the sand. However, Californian Bearing Ratio, suction, UCS, maximum deviatory strength and secant modulus increased with the increasing percentage of sand added. They reach their maximum value when the portion of sand incorporated ranged between 25 and 35%. The optimal formulation of 65% tuff and 35% dune sand was selected to meet economic and environmental constraints. This analysis showed that the dune sand incorporation improved the geotechnical characteristics and the mechanical behavior of the tuff. It provided a better elaborated material; satisfying the standards requirements, which could be exploited for the construction of Saharan roads.