Determination of the mechanical characteristics of jet grout columns constructed by using different cement types and investigation with ultra sound method

In this thesis, the performance of different cement types in the improvement of sandy soils by Jet Grout (JG) method was investigated. The cements used are DMFC-800 fine grain cement, CEM I 42.5 R normal Portland cement, CEM II 42.5 A-M (P-L) Portland cement and CEM III / A 42.5 N blast furnace slag (YFC) admixtured cements. CEM I 42.5 R normal Portland cement (without additives) was selected as the reference cement type for the interpretation of the performance of other cements. First of all, rheological properties of cements were determined. For this purpose, Marsh funnel, simple plate cohesion meter suggested by Lombardi, sedimentation tests and Vicat setting time tests were performed. In the light of the data obtained from these experiments, the water / cement (W/C) ratios to be used in cement injections were decided. After determining the injection recipes, small scale cylinder samples were prepared. These samples were subjected to unconfined compressive strength (UCS), splitting tensile strength test (STS) at the end of the cure times of 7, 28 and 56 days. Permeability tests subjected after 56 days of cure time. In addition to small scale experiments, model JG columns were formed in large barrels by using model JG apparatus installed in the laboratory. The same W/C ratios were used in large-scale experiments as in small-scale experiments. At the end of the 90-day curing period, core samples were taken from these large-scale columns and unconfined compressive strength test, splitting tensile strength test, permeability test and uştrasonic pulse velocity (UPV) test were applied. In addition, scanning electron microscopy (SEM) image analyzes were performed from samples selected from strength tests. The highest strength results were obtained at the end of 7 days of cure time from samples prepared with DMFC-800 cement. CEM II and CEM III admixtured cements showed lower strength at the end of 7 days of cure time as they contain clinker substitutes. Admixtured cements performed better than CEM I cement after 28 days curing period. CEM II and CEM III cements showed higher strength results than fine-grained cement after 56 days of curing. The rheological properties of cement injections were effective on the results of the performance of core samples taken from large scale columns. The rheological properties of the injection affected the ability to penetrate the soil, and there were differences according to the results of small-scale samples. The UPV test results were substantially parallel to the strength and permeability test results.