Desiccation Cracking Behavior of Sustainable and Environmentally Friendly Reinforced Cohesive Soils
Type of DegreeMaster's Thesis
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Desiccation cracking of cohesive soils is the development of cracks on the soil surface as a result of a reduction in soil water content. The decrease in soil surface area owing to the desiccation of cohesive soils has an undesirable impact on the mechanical, hydrological, thermal, and physico-chemical properties. Many efforts have been made to improve the desiccation crack resistance of cohesive soils, the most being chemical treatment using additives like cement and lime. Unfortunately, their use raises a number of environmental issues, so the demand for sustainable and environmentally friendly soil improvement alternatives is rapidly increasing. Therefore, the main objective of this study is to investigate eco-friendly soil improvement techniques and their effect on the desiccation cracking behavior of soils. Improvement of soil crack resistance was studied by conducting desiccation cracking tests on two types of soils: Piedmont soil and white kaolin clay. Fly ash, recycled carpet fibers, bioplastic, and xanthan gum were all studied as potential sustainable soil improvement techniques. Unimproved and sustainably improved soils were compared by utilizing desiccation and mechanical tests. In addition, two types of image processing were conducted to quantitatively describe the effect of reinforcement on the geometrical characteristics of crack patterns. The experimental and image analysis results showed that soil improvement techniques generally enhanced the soil strength and reduced cracking. The results from the physical tests were used along with data from other studies to calibrate a predictive hydro-mechanical numerical-analytical model. The model utilized soil-specific material properties in order to predict unsaturated water flow. This water flow was then used to model the strains and stresses that develop in the soil as a result which in turn predicted the initiation of desiccation crack behavior. Specific soil material properties were altered for the various soil improvement techniques. The model predicted the development of stresses and radial displacements as well time of crack initiation for untreated and improved specimens.