Investigation of hydro-mechanical property for unsaturated expansive soil using developed suction control system

This study focuses on changing the unconfined compressive strength of unsaturated compacted bentonite-sand mixture specimens to produce a suction distribution using a developed high-suction- controlling system. The system consists of an air-circulation-flow performance and vapor-pressure technique, which creates high suction more than 2.8 MPa. Different high suctions are applied to the upper and bottom portions in the developed system for compacted bentonite-sand mixture specimens that range from 2.8 MPa to 296 MPa in suction (corresponding to from 98 % to11 % in relative humidity). The soil water characteristic curve was also immediately measured in order to investigate a correct suction distribution. The relationship between suction and unconfined compressive strength was established to confirm the influence of suction on shear resistance. Then, decision of unconfined compressive strength for the suction distribution was compared with the strength at each suction value. The obtained results are interesting because the suction distribution case the reduction of shear strength in unsaturated bentonite sand mixture specimens.