Consequences of Initial Compaction States on Desiccation Cracking and Mechanical Behaviour of Fine-Grained Soils Subjected to Wetting-Drying Cycles

Abstract

Due to the water loss in a dry environment, desiccation cracking often occurs in fine-grained soils. The process of tensile tension begins when water evaporates from soil in a drying environment. One possible symptom of desiccation cracking is an increase in tensile stress as the water content decreases. An extensive body of research has shown that several variables, such as mineral make-up, fine-grained content, temperature, boundary conditions, relative humidity, wetting-drying cycles, sample size, etc., influence desiccation cracking. Desiccation cracking has a major impact on the hydraulic and mechanical characteristics of soils, which means it might potentially harm hydrological regimes and geotechnical engineering. Soil strength and compressibility may be diminished by desiccation fractures. According to pavement engineers, roads may not last as long as expected if fissures degrade the mechanical qualities of the subsoil. Also, the desiccation fractures may be a great method for rainwater to seep in and for gas to escape. Landfill cover systems may cause crack-induced preferred routes, which can contaminate both the air and groundwater. Additionally, it may cause dikes and levees to fall catastrophically, which would have a devastating effect on the environment and economy. Desiccation cracking behaviour of fine soils is examined in this work by examining the impacts of compaction states and wetting-drying cycles. Different samples with various compaction water contents and dry densities are formed using high and low plastic soils, after applying the standard proctor test to find out the OMC and maximum dry densities of low and high plastic soils. These samples are subjected to 4 wetting-drying cycles and the evolution of desiccation cracks will be quantitively analysed by crack image analysis system (CIAS) using ImageJ software. Then the mechanical behaviour of fine soil is observed using unconfined compression strength and consolidation test, and micro characteristics of the low and high plastic soil are identified using the scanning electron microscopy (SEM), X-Ray diffraction, minerology, and chemical composition test. Overall, in high plastic clays (CH), the maximum surface crack ratio, total crack length, crack line density and crack area are observed in the samples remoulded at optimum moisture content. But the UCS results show that the axial stress decreases as the wetting drying cycles proceed. Consolidation tests on CH, CL shows that the influence of wetting drying cycles and initial compaction states has same trend for both soils. When comparing samples remoulded at the different moisture contents the compression index increases as the moisture content decreases.