Keynote Lecture: Recent development of quality control and assurance of deep mixing method

The Deep Mixing Method (DMM), a deep in-situ soil stabilization technique using cement and/or lime as a binder, was developed in Japan and in the Nordic countries independently in 1970s. Due to its wide applicability and high improvement effect, the method has gained increased popularity in many countries. The quality control and assurance is one of the major concerns for clients and engineers who have less experience of the technologies. However, there may be many differences in the QC/QA procedures. Diversification of application, soil type, and execution system, together with the improved understanding on the behavior of improved ground necessitate our profession to review the current QC/QA practice. In the manuscript, the importance of QC/QA related activities along the work flow of deep mixing project is emphasized and the current and recent development of QC/QA are also presented.