Effect of Cutter Soil Mixing (CSM) method and curing pressures on the tensile strength of a treated soft clay

This study presents a set of laboratory experiments to investigate the effect of Cutter Soil Mixing (CSM) method and curing pressures on the tensile strength of a soft clay treated with Air Cooled Blast Furnace Slag (ACBFS) and Industrial Hydrated Lime (IHL). High productivity, minimum vibration, using the in-situ soil as construction material, and high level of quality control are some of the main benefits of CSM method. Three different slurries containing various percentages of ACBFS and IHL were mixed with saturated soft clay due to CSM method to enhance its tensile strength and make it suitable for the construction of deep CSM panels. To simulate high pressure due to the self-weight of the deep CSM panels in the field, a number of high pressure curing devices were designed and built in the laboratory and used for 28 and 56 day pressurised curing of the treated samples. Then an indirect tensile strength test was performed on the treated samples to investigate the effect of mixing method, ACBFS-IHL content, curing pressure and curing time on the tensile strength of the treated material. Finally, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis were conducted to investigate the microstructural and properties of the treated clay. The outcomes demonstrate that using CSM method and curing pressures along with ACBFS-IHL as a chemical stabiliser, increases the tensile strength of treated soft clay up to 35 times, which is significantly higher than the use of chemical stabiliser alone. Moreover, the microstructural analysis results revealed that the main hydration products in the clay treated with ACBFS-IHL is gismondine (C-A-S-H) which is also considered to be responsible for the higher tensile development.