One typical problem in the construction of low volume roads in the Eastern Province of Saudi Arabia and along the coast of the Gulf is the presence of sabkha soil. Sabkha is a saline, evaporative flat soil that forms under arid climates. It is generally associated with saturated watertables that are very close to the ground surface. Sabkha loses its strength when wet. Near the Gulf coast, the ground watertable is usually high and it can be higher than the pavement surface level in some locations. Hence, sabkha is considered very poor as a subgrade for road construction in the Gulf region. This study investigates the effectiveness of using geotextile fabrics on the top of sabkha subgrade under thin untreated bases that are typically used with low volume roads. The investigated parameters include: type of geotextile fabric, thickness of untreated base, sabkha subgrade moisture condition and the level of loading. Results of permanent deformation under repeated loads have shown that there is a great reduction in rutting susceptibility of the reinforced sabkha subgrade. This was more significant when comparing dry to wet conditions. Also, the bearing capacity of the sabkha subgrade soil has increased considerably by geotextile fabrics reinforcement. As the thickness of the untreated base increases, the effect of the geotextile reinforcement becomes ineffective. This indicates the importance of the use of the geotextiles in low volume roads where the base thickness is usually small.
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