Development of transparent cemented soil for geotechnical laboratory modelling

This paper introduces transparent cemented soil as a surrogate for the physical modelling of geotechnical problems. The transparent soil consists of fused quartz particles that form the soil skeleton combined with a mixture of hydrophobic fumed silica powder and mineral oil that forms the cement material. Conventional isotropically consolidated undrained compression (CIU) tests and falling head permeability tests were carried out, demonstrating that the proposed transparent soil has similar mechanical properties and hydraulic permeability to those of natural cemented soil with clay as cement. The same triaxial and permeability tests were carried out on transparent cemented soils with increasing fumed silica contents to investigate the cement content's influence on mechanical properties. The results show that transparent cemented soils with increased fumed silica content have more effective strength, stiffness and cohesive force. In addition, the increased fumed silica content reduces the permeability of transparent soil. To demonstrate the practicability of the proposed material in geotechnical model tests, a laboratory slope model test was conducted. The proposed surrogate has high transparency, with a visible depth of 20 cm, and is compatible with image-based techniques for the following deformation measurement. Moreover, the transparent cement soil has the unique advantage of showing shear band propagation, which is invisible in conventional physical modelling.