Investigation of the Effects of Mixtures of Fly Ash and Cement Types on Jet-Grout Columns

In recent years, the jet-grout (JG) technique has been one of the most preferred soil improvement methods. The specimen column diameter-length, grouting pressure, rod linear-rotational speed, nozzle diameter-number, water/cement ratio, cement properties, and soil properties are the main factors affecting JG column performance. In this study, cement and cement mixture injections, cement particle size, fly ash, and water/binder (cement) ratio were investigated as factors affecting the performance of Jet-Grout columns formed in the laboratory at various water/cement ratios. The mixes made by mixing microfine cement, normal Portland cement (NPC), and fly ash (FA) in various water/cement ratios resulted in four different types of binders. The unconfined compressive strengths of core samples taken from formed Jet-Grout columns were examined. While fly ash had no positive impact in low water/cement ratio mixes, it did have an effect in high water/cement ratio mixes, where the water content and column diameters increased as the water/cement ratio increased.