A STUDY OF SAND STABILIZATION IN EASTERN SAUDI-ARABIA

Saudi Arabia as well as many of the Arabian Gulf countries have witnes sed extensive programmes of industrialization and urbanization in the last few decades. In the eastern part of Saudi Arabia these unpreceden ted activities have resulted in some unexpected constructional problem s attributed to the lack of proper quality soil and unfamiliarity with the inferior properties of these soils. The abundance of fine to medi um, non-plastic, wind-blown sand deposits at shallow depths makes such soils attractive for construction purposes. However, the poor quality of these soils, especially their low bearing capacity, makes it neces sary to improve their properties by stabilization. In an attempt to as sess the strength properties of stabilized granular soils and to evalu ate the behaviour of cement-treated sands, stabilized samples were pre pared and tested in the laboratory under controlled conditions. Two ty pes of cementing agent were used: Portland cement and calcium carbonat e. The effects of some of the variables encountered in the field such as curing type and time, confining pressure, cementing agent content, density, saturation and reconstitution on the behaviour of stabilized soils, were studied. Test results show that the addition of a cementin g agent to a wind-blown sand (cohesionless material) with uniform size distribution produces a material with two strength components - that due to cementation or ''true'' cohesion and that due to friction. The angle of internal friction for the treated sands is not much different from that of the untreated sand. The results also show that the dryin g process is essential in the development of cementation, especially w hen calcium carbonate is used as the cementing agent. Peak strength as well as initial tangent modulus values, increase with an increase in curing period, confining pressure, cement content and density. Residua l strength values seem to be independent of all parameters other than the confinement and density; a behaviour commonly observed for uncemen ted sands.