This thesis provides a detailed study on optimisation of cementitous treated soft clay soils in the South East Queensland region. A comparative study has been performed comparing the behaviour of cement and lime treated compressible clays from both Bangkok and South East Queensland. The purpose of the comparative study was to evaluate change in strength properties of treated soft clay soil as well as providing parameters for case studies using different analysis methods. This thesis compares the behaviour of soft clay treated with cementitous materials in South East Queensland and Bangkok. Overall it was concluded that the addition of cement and lime has favourable effects on the strength characteristics of South East Queensland soft clays.