Laboratory Procedure to Obtain Well-Mixed Soil Binder Samples of Medium Stiff to Stiff Expansive Clayey Soil for Deep Soil Mixing Simulation

This paper presents a laboratory procedure to prepare well-mixed soil binder samples for simulation of deep soil mixing to stabilize medium stiff to stiff expansive clayey soils. Two natural clays were selected, and stabilized with lime, cement, and combinations of both at various proportions and dosages. Results obtained from tests conducted on identical specimens showed that the current soil-binder mixing and specimen preparation procedures have yielded homogenous and uniform treated clayey specimens. Engineering properties measured on the treated soil specimens were analyzed and ranked to arrive at the optimum binder dosages for field implementation. Concurrent mineralogical studies on selected specimens using X-ray diffraction and scanning electron micrograph studies revealed the presence of pozzalonic compounds and interwoven threads in the treated samples indicative of the mixing and stabilizing phenomenon. The recommended chemical dosages were later implemented in a field deep mixing study to construct two test pads. Several in situ wet grab samples were collected from the treated ground and were subjected to strength and stiffness tests in the laboratory. Comparisons between test results from field cores and laboratory fabricated specimens showed a good match suggesting that the formulated test protocol has provided a reasonable simulation of the DM process.