During jet grouting, the in-situ soil is mixed with cement grout which is discharged laterally into a borehole wall in order to form a column-like structure of improved soil. Recently, the heat release during cement hydration was exploited for identification of main properties of jet-grouted columns, i.e. the amount of cement in the improved soil and the column radius. Hereby, a material model for the simulation of the hydration process is combined with on-site temperature measurements. In this paper, the back-analysis scheme used for identification of the properties of jet-grouted columns is refined as regards the underlying hydration model. Hereby, the overall degree of hydration with one kinetic law is replaced by a multi-phase hydration model, taking the hydration kinetics of the main clinker phases into account. In order to reduce costs of ground improvement, blended cements are commonly used (ordinary portland cement mixed with blast furnace slag, fly ash, silica fume, and lime stone). The effect of slag hydration is incorporated into the presented multi-phase model. The developed hydration model for both plain and blended cement is validated by means of differential-calorimetry (DC) experiments. Finally, recent applications of the mentioned back-analysis tool using the multi-phase hydration model, illustrating the determination of the diameter and the cement content of jet-grouted columns for a construction site in Vienna, Austria, are presented.
