Effect Of Curing And Environmental Conditions On Unconfined Compressive Strength Of Clay Stabilized With Lime And Nano Silica

نوع: Type: thesis

مقطع: Segment: masters

عنوان: Title: Effect Of Curing And Environmental Conditions On Unconfined Compressive Strength Of Clay Stabilized With Lime And Nano Silica

ارائه دهنده: Provider: Mohsen Abdolmaleki

اساتید راهنما: Supervisors: Dr. Meysam Zarinfar

اساتید مشاور: Advisory Professors:

اساتید ممتحن یا داور: Examining professors or referees: Dr. Abas Qadimi - Dr. Salahedin Hamidi

زمان و تاریخ ارائه: Time and date of presentation: 2022/10/18

مکان ارائه: Place of presentation: Civil engineering seminar room

چکیده: Abstract: A large part of the earth's surface is made up of fine-grained and clay soils, which are usually weak and problematic. Therefore, to overcome this weakness, improvement, and stabilization of these types of soils are considered. In this research, the stabilization of kaolinite clay using lime and different percentages of nanosilica has been discussed. In order to investigate the effect of environmental and curing conditions on the soil stabilization process, soil samples with the optimum lime content (OLC) and different amounts of nanosilica (5%, 10% and 15% replacement with lime) were mixed. In terms of curing humidity, the samples were placed under three environmental conditions of 0% and 40% relative humidity and submerged in water. In terms of curing temperature, they were kept at three ambient temperatures of 10, 25 and 40 degrees of Celsius. These samples were tested for unconfined compressive strength (UCS) in three curing periods of 7, 14 and 28 days. The results of these tests have generally shown that in any environmental and curing conditions, the addition of nanosilica has increased the strength of the soil stabilized with lime. In almost all the samples, the increase in temperature caused an increase in the compressive strength of the samples. In the 7-day samples, there is no significant difference between the strength obtained by the samples stored at 0 and 40% humidity, but in the long term, higher relative humidity of the environment causes more strength to be obtained. In the long term (28 days), the samples that were immersed in water gained the greatest strength. On the other hand, replacing a part of the existing lime in the mix design with nanosilica can significantly improve the weakness in the strength of soil stabilization with lime at low temperature. In terms of the length of the curing time, the addition of nanosilica causes a greater improvement in the strength of the 7-day samples compared to the 14- and 28-day samples. In other words, the speed of increasing the strength in the soil stabilization process with lime increases with the presence of nano silica. In order to investigate the microstructure of the influence of environmental conditions on the stabilization of kaolinite clay with lime and nanosilica, XRD tests were performed on several samples. XRD test results show that nanosilica as a pozzolanic material in the soil-lime mixture, by helping to increase the production of pozzolanic products (especially CSH), causes an increase in the strength of clay stabilized with lime. At the same temperature, the increase in humidity alone increases the CSH produced in the soil, which results in an increase in the strength of the samples