In recent years, there has been an increase in the application of the jet grouting method under existing buildings. In order to reduce the environmental load and rationalize construction, the authors have developed a technology to reduce the amount of sludge discharge by reducing the amount of cement milk injected into the ground. As a result of in-situ experiments, the amount of sludge discharge was reduced by 30%, and it was confirmed that the improved diameter, strength, and coefficient of variation were equivalent to those of the conventional specifications.
