چكيده به لاتين
One of the existing challenges in the jet grouting method is to ensure that formed columns have a predicted shape, diameter, and strength. Thus, identifying the effective factors and examining their influence on the characteristics of the jet grout columns seems important. Installation of mold before implementing jet grout columns using casing in the ground leads to a geometrical arrangement and well-arranged formation of columns. In addition, by using concrete additives in the used grout, parameters of the formed columns, including the compressive strength, can be enhanced. This research used superplasticizers, air-entraining admixtures, and microsilica (silica fume) to form the confined soil-cement columns by jet grouting. Also, their influence on the improvement of strength and behavior parameters was examined.
In this study, superplasticizers were utilized to reduce the water/cement ratio, micro silica to increase the strength and decrease porosity, and finally, air-entraining admixture to increase porosity and create permeability in the soil-cement columns.
Regarding the obtained results and their comparisons, it can be observed that the influence of the diameter of cement-soil particles did not show a considerable impact on the compressive strength in the research. Also, the improved grout comprises the main portion of the strength.
In the air-entraining admixtures, we have seen an increase in porosity of about 26% and as a result a decrease in compressive strength, in the main samples the compressive strength was in the range of 10 to 18 MPa and in the core samples it was about 4 MPa. In the superplasticizer, due to the reduction of water to cement ratio and the inherent property of superplasticizer, we have seen a decrease in porosity in the range of 4% to 8% and a significant increase in compressive strength, in the main samples 18 to 25 MPa and in the core Is 26 to 32 MPa. The optimum percentage of microsilica in this study is 10% by weight of cement and has been obtained as an alternative, which has increased the compressive strength, in the main samples of compressive strength in the range of 14 to 26 MPa and core samples in the range of 15 to 20 It is megapascals and the obtained porosity is about 8%. At 15% and 20% microsilica ratios, we have seen an increase in porosity of about 13.5% and 19%, respectively, and as a result, the compressive strength has been reduced. The compressive strength of these samples is in the range of 6 to 13 MPa.
