Effect of Freezing and Thawing on Unconfined Compressive Strength of Clayey Soil Mixed with Crumb rubber and Modified by Lime

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Effect of Freezing and Thawing on Unconfined Compressive Strength of Clayey Soil Mixed with Crumb rubber and Modified by Lime

ارائه دهنده: Provider: Saber Mousapour

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

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: دکتر مسعود مکارچیان - دکتر عباس قدیمی

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

مکان ارائه: Place of presentation:

چکیده: Abstract: Since the soil of the project plant mostly has not all of geotechnical properties required for the project, studies on the soil improvement has great importance. Due to the abundance of the clayey soil in Iran, and also, their challenges such as compressive weakness and sensitivity to the freezing, improvement of clayey soils attracts investigators' attentions these years. Stabilization with lime and cement and randomly distributed fiber reinforcement are important soil improvement methods. Among fibers used in soil reinforcement, usage of waste rubber is imperative considering environmental point of view. Due to the environmental issues caused by the storage of waste rubbers, the application potential of waste rubber in soil reinforcement was evaluated in recent researches. The results showed that the effect of crumb rubber on the soil geotechnical characteristics depends on soil type, type and rubber geometry and rubber content in the mixture. This research aims to investigate the simultaneous effect of stabilization by lime and reinforcement by crumb rubber on unconfined compressive strength of clayey soil under freezing and thawing condition. To this end, lime with the content of 2, 4, 6 and 8 percent and crumb rubber with the content of 2 and 4 percent were mixed with the kaolinite soil, and unconfined compressive strength tests were performed on the samples. Furthermore, in order to study the effect of freezing and thawing cycles, the samples were exposed to maximum 3 freezing and thawing cycles. The results of unconfined compressive strength tests revealed that the addition of lime to the soil up to 6 percent increases unconfined compressive strength, decreases failure strain and increases hardness of the samples. Addition of lime with the content of upper than 6 percent decreases the unconfined compressive strength of the samples. According to the results, addition of crumb rubber to the soil decreases the unconfined compressive strength, increases the failure strain and decreases the hardness of the samples. In other words, addition of crumb rubber to the soil results to the softer behavior. Based on the results, unconfined compressive strength of the samples decreases under freezing and thawing condition, and the maximum strength loss was occurred in the first cycle. Addition of lime to the soil also increases the unconfined compressive strength of the samples under freezing and thawing condition, while crumb rubber decreases the soil strength. The results show that as the number of freezing and thawing cycles increases, the difference of unconfined compressive strength between samples with and without crumb rubber decreases. The results of this study reveal the potential application of waste crumb rubber in soil reinforcement considering the reduction of environmental issues and softening of the soil behavior. Key Words: Soil Improvement, Soil Stabilization with Lime, Soil Reinforcement with Crumb Rubber, Unconfined Compressive Strength, Freezing and Thawing

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