Structural and behavioral analysis on gellan treated soils

Abstract

Soil treatment and improvement have been an important field for construction since an-cient times, where the use of bitumen or sticky rice mortars have been used for soil strengthen-ing. Since then with the advancement of civilization, the durability and construction materials have improved allowing for further advancements in the field of geotechnical engineering. The main purposes of soil improvement has been the enhancement of one or many engineering characteristics of the soil. Such characteristics include the strength, hydraulic conductivity, dura-bility, and the revitalization of the environment. Among the soil treatment methods, the most widely used and accepted is the use of cement. The use of cement has a long standing history and numerous advantages, such as high strength and durability with an ability to form calcium carbonate crystals under the water table. However, the use of cement has also been associated with various environmental concerns, such as the heavy emission of greenhouse gases, urban runoff and heat, and vegetation growth limitations. Due to the many environmental hazards associated with cement use, research and devel-opment into an environmentally friendly substitute for a soil binder has been researched in re-cent years. Environmental-friendly and sustainable approaches have recently emerged in the field of geotechnical engineering which involve the use of alternative materials, including geo-synthetics, chemical polymers, geopolymers, or biological treatment. Among such research one possible avenue for an environmentally friendly soil binder is the use of biopolymers. Biopolymers are organic polymers that are synthesized by biological organisms. They consist of monomeric units that are bonded into larger formations. In this study, gellan gum biopolymers are used for soil improvement purposes, and an in-depth study on the structure and behavior of gel type biopolymers has been conducted. The use of various experiments such as the uniaxial compressive strength, direct shear tests, hydraulic conductivity tests, and oedometer tests have been performed to analyzed the structure and behavior of these gellan treated soils. Specifically with a focus on the presence of clay particles and water molecules. These investigation provided numerous insights into the properties of these gellan treated soils, and the importance of many factors, such as the gellan to clay ratios.