the Effects of Different Types of Lime with GGBFS Slag on Stabilization of Clayey Soil

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: the Effects of Different Types of Lime with GGBFS Slag on Stabilization of Clayey Soil

ارائه دهنده: Provider: milad fereidunifar

اساتید راهنما: Supervisors: dr.masoudmakarchian

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: dr.mohamd maleki and dr. misam zarinfar

زمان و تاریخ ارائه: Time and date of presentation: 2022

مکان ارائه: Place of presentation: سمینار عمران

چکیده: Abstract: Clay soils often cause problems in construction projects. Weak resistance and sensitivity to alternating cycles of freezing, thawing, wetness and drying are among these issues. Humanity has been trying to overcome these challenges with different methods and solutions for a long time, and it is necessary to justify these methods, their economic and practicality. In this thesis, lime, slag and calcium carbide are used to stabilize kaolinite clay. The used slag is of GGBS type, which is used as a substitute for a part of the lime used in clay stabilization, and it was procured from Isfahan Zob Ahan Joint Stock Company. The calcium in lime reacts with the sulfate in the soil along with the aluminum released from the soil and forms a material called ettringite. Etteringite is an unstable crystalline substance that changes its volume when hydrated and greatly reduces soil resistance. The destructive role of sulfates in soils stabilized with lime has been studied by researchers for several years. Sulfate ions can be supplied through sulfated soils or by water containing sulfate ions that flows into the modified soil and enters into the chemical interactions of lime and calcium carbide and clay. The soil used is clay with low pasty properties, which is mixed with different percentages of lime, calcium carbide and slag in the optimal moisture percentage, and after compaction, tests of freezing and thawing, wetness and dryness in drinking water, wetness and dryness in solution Sodium sulfate and magnesium sulfate and unconfined compressive strength have been accepted. The percentage of material mixing according to the results of the unconfined compressive strength tests of Motokva Pride (2019) it's been chosen. The test samples were processed in four different combinations at a temperature of 35 degrees Celsius and for 28 days in a greenhouse. For each of the four tests conducted in this research, four different composites were subjected to unconfined pressure test after each cycle. On average, the samples could withstand up to six test cycles. Therefore, at least 21 samples were made for each combination in each experiment, which includes a total of 336 samples. In the freezing and thawing test, after processing and leaving the oven, the samples were taken out of the mold and frozen at -23 degrees Celsius, and were thawed in a chamber without moisture exchange with the environment. or the three wet and dry tests, considering that the samples were completely disintegrated and destroyed after being placed in the tested solution; The samples were tested together with the PVC mold. The results of the experiments show that slag together with lime and calcium carbide can be effective in reducing the sensitivity of stabilized soil against freezing and thawing and wet and dry cycles. Also, the positive effect of slag can be seen in the tests of placing samples in sodium and magnesium sulfate solution; Also, by comparing the results of the tests, it can be seen that the destructive effect of freeze-thaw cycles is more than other tests, and wetting and drying are less than others, and sodium sulfate and magnesium sulfate solutions are in between. According to the results of this research, the use of calcium carbide, which is a byproduct of acetylene gas production, can be an alternative to lime, and its combination with slag makes this alternative better

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