Past, present, and future of transparent soils

Transparent soils have evolved in the past two decades as a useful tool for the physical modeling of soil-structure interaction mechanisms, saturated-unsaturated hydraulic behavior, and thermal processes in soils. This paper traces the history of the development of transparent soil surrogates used in laboratory 1-g bench-scale and centrifuge tests to investigate a variety of geotechnical applications. Many notable papers that appear in this special issue of the journal on modeling with transparent soils are introduced throughout the review. The paper also looks into the future to anticipate where further advances and applications of these materials and complementary technologies may be expected.