Effect of soil type and sample preparation method on uniaxial resistance of cement-stabilized soils

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Effect of soil type and sample preparation method on uniaxial resistance of cement-stabilized soils

ارائه دهنده: Provider: Leila Heydari

اساتید راهنما: Supervisors: Mahdi Esna Ashari (Ph.D)

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: دکتر عباس قدیمی - دکتر محمد ملکی

زمان و تاریخ ارائه: Time and date of presentation: 2020 November, 18

مکان ارائه: Place of presentation:

چکیده: Abstract: Soils are found in nature in different ways. For various reasons, improving the quality of soil in terms of strength and durability in construction is essential, in which consolidation is a suitable and effective solution. Cement has always been considered as one of the soil stabilizers. Stabilized sand has a variety of uses, including underlying roads and airports. Clay soils also usually have low strength and load-bearing capacity. The problem of lack of clay resistance can also be solved by stabilization. Soil stabilization steps, including cement spreading, soil mixing and cement, cause pollution in the environment. Scattering of cement particles in the air is a source of pollution that dangers the health of humans, animals and plants. Therefore, in this study, while investigating the effect of soil type on uniaxial compressive strength of cement-stabilized soil, the method of stabilization has also been investigated by examining the effect of sample preparation method on strength. In this study, the behavior of 4 types of cement-stabilized soils has been studied by uniaxial compressive strength test. For this purpose, samples of pure kaolinite clay with the abbreviation 100 CL, sandy soil with the abbreviation 100S, mixed soil with 65% sand composition and 35% kaolinite clay with the abbreviation 65S, mixed soil with 35% sand composition and 65 Kaolinite clay with the abbreviation 65CL, with cement in the proportions of 0,2,6,6,8,10% of the dry weight of the soil is prepared in two different ways. The samples were stored in a oven at 32 ° C for 3 and 7 days. In the first method (called method A), first the soil is mixed with cement and then water is added to it. In the second method (called method B), first cement and water are mixed together and prepared as a slurry and then added to the soil. In both methods, the amount of water required was 1 to 2% more than the optimum moisture obtained from the compaction test. In another part of experiments and sampling by method B, by reducing the amount of water to the optimum humidity and adding lubricant, the effect of this additive on compressive strength has been investigated. In this study, two types of lubricants have been used as conventional reducers with the abbreviation N50 and strong water reducers with the abbreviation P9-3R with a weight of 3% by weight of cement. The strength of soil samples of 100CL, 65S and 35S prepared by A, B method (without lubricant and with two types of lubricants) increases with increasing cement up to 10%. The strength of 100S soil samples prepared by methods A, B (without lubricant) increases with increasing cement up to 10%. The strength of lubricant samples of 100 S increased with increasing cement up to 8% and decreased from 8 to 10%. Increasing the processing age also increased the strength in all samples. Preparation method B increases the strength in 100S (coarse-grained) soil. This increase depends on the amount of cement. In 100 CL (fine-grained) soil, preparation method B reduces unlimited compressive strength. In mixed 65S and 35S soils, the higher the amount of kaolinite (fine-grained), the more sample preparation by method B reduces the compressive strength of the samples. The strength of 65S soil samples, prepared by both methods A and B (with lubricant and without lubricant) in different percentages of cement and at processing ages of 3 and 7 days is higher than the strength of the other three soil types and 100S less soil. Comparison of soil strengths of 65S and 35S with 100S has shown that the replacement of kaolinite clay with sandy soil in cement soil stabilization increases the strength. Adding lubricant to 4 types of soil reduces compressive strength. The effect of P9 lubricant in reducing soil resistance of 100 CL (fine-grained) is more than N50 additive. The effect of N50 additive in reducing soil resistance of 100 S (coarse-grained), 65S and 35 S mixed soils (coarse-grained and fine-grained) is greater than that of P9 additive. Key Words: Stabilization, cement, unlimited compressive strength, lubricant, sand, kaolinite clay

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