Resilient Modulus of Expansive Soils at High Suction Using Vapor Pressure Control

Abstract

Robust design of pavement sections underlain by high-plasticity subgrade soils requires determination of subgrade resilient modulus over a wide range of suction to account for seasonal and diurnal variation of moisture. A laboratory experimental apparatus capable of performing suction-controlled repeated load triaxial tests at high suction (5 to 600 MPa) has been developed by integrating automated vapor pressure control to the specimen gas phase within a cyclic triaxial setup. The system eliminates limitations on applicable upper-bound suction that exist in more commonly adopted axis-translation approaches. This article describes the experimental setup, its working principle, and test procedures. Results are presented for a high-plasticity clayey soil to demonstrate testing capability for suction ranging from 5 to 100 MPa. Results show repeatability having an average coefficient of variation of less than 6 % for all loading sequences.