Improvement of the bearing capacity of confined and unconfined cement-stabilized aeolian sand

The improvement reached on the compaction and bearing capacity of aeolian sand collected in Jeddah (Saudi Arabia) after its stabilization with Portland cement is evaluated, comparing the behavior for both treated and untreated samples. With the aim of using this type of soil in the construction of embankments for road or railway applications, the results obtained have been evaluated in terms of maximum dry density, optimum moisture content (compaction test) and bearing capacity (CBR). Special attention has been paid to the influence of the confining conditions on the results, scarcely analyzed in the literature, by comparing the load-displacement curves during penetration stage in the CBR tests for both confined and unconfined specimens. Different contents of Portland cement have been explored (out of 6% of dry soil weight) to stabilize this material. The results obtained show a clear linear correlation between of compaction characteristics and CBR respect to the percentage of cement, obtaining, as expected, higher improvement for treated-material with higher content of cement, also strongly influenced by the confinement state. Thanks to this treatment, it is possible to employ this material in applications with low-confinement support, which is impossible without a previous proper stabilization. Finally, two practical indices have been defined to measure the degree of improvement reached, involving both cement content and confinement.