Heat curing method and laboratory performance evaluation of subgrade soil stabilized with bentonite and magnesium alkalinization
department or school: Applied Science, Faculty of
department or school: Engineering, School of (Okanagan)
data provider: DSpace
degree campus: UBCO
creator: Sabrin, Sohana
issued: 2019-09-30T07:00:00Z
issued: 2019
related degree: Master of Applied Science - MASc
degree grantor: University of British Columbia
description: Alkalinization of problematic soils with silica and alumina rich material to improve their mechanical properties has become a popular practice globally. However, the application of alkalinization process to improve road bases and subbases namely subgrades are limited. Besides, the properties and performance of alkalinization process are dominated by several factors mainly initial curing conditions, concentration of alkaline activators and composition of materials. This study is aimed to investigate the effect of curing condition (temperature and duration) on unconfined compressive strength, elastic modulus (E50), microstructure and freeze thaw durability of silty sand subgrade soil stabilized with bentonite magnesium alkalinization. The selected curing temperatures and durations included ambient temperature, 40°C, 60°C and 80°C for 1 day and up to 3 days. Results revealed that curing at ambient temperature or as low as 40°C is not enough to achieve desirable strength while further increase in temperature favored substantial strength development. However, the properties of samples cured at elevated temperature for longer duration significantly deteriorated at later age (60 days) compared to the properties of samples cured at a slightly lower temperature. The optimal development of unconfined compressive strength and E50 observed when samples cured at 60°C for 3 days and the degree of improvement is 7 times compared to the natural soil. In addition, the scanning electron microscopy (SEM) images revealed presence of cementitious gel resulted from stabilization process. The data from energy-dispersive spectroscopy (EDS) and thermogravimetric analysis (TGA) confirmed the presence of cementitious gel magnesium silicate hydrate (M-S-H) and calcium silicate hydrate (C-S-H) which made the samples more compacted and stable with time. Finally, higher unconfined compressive strength loss was observed during freeze thaw durability test but the samples were capable to withstand a…
aggregated CHO: https://circle.library.ubc.ca/rest/handle/2429/71710
note: HEAT CURING METHOD AND LABORATORY PERFORMANCE EVALUATION OF SUBGRADE SOIL STABILIZED WITH BENTONITE AND MAGNESIUM ALKALINIZATION by Sohana Sabrin B.Sc., Khulna University of Engineering & Technology, 2014 A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF MASTER OF APPLIED SCIENCE in THE COLLEGE OF GRADUATE STUDIES (Civil Engineering) THE UNIVERSITY OF BRITISH COLUMBIA (Okanagan) September 2019 © Sohana Sabrin, 2019 ii The following individuals certify that they have read, and recommend to the College of Graduate Studies for acceptance, a thesis/dissertation entitled: Heat curing method and laboratory performance evaluation of subgrade soil stabilized with bentonite and magnesium alkalinization submitted by Sohana Sabrin in partial fulfillment of the requirements of the degree of Master of Applied Science in Civil Engineering . Dr. Sumi Siddiqua, School of Engineering Supervisor Dr. Solomon Tesfamariam, School of Engineering Supervisory Committee Member Dr. Ramy Saadeldin, Adjunct Faculty, School of Engineering Supervisory Committee Member Dr. Jahangir Hossain, School of Engineering University Examiner iii Abstract Alkalinization of problematic soils with silica and alumina rich material to improve their mechanical properties has become a popular practice globally. However, the application of alkalinization process to improve road bases and subbases namely subgrades are limited. Besides, the properties and performance of alkalinization process are dominated by several factors mainly initial curing conditions, concentration of alkaline activators and composition of materials. This study is aimed to investigate the effect of curing condition (temperature and duration) on unconfined compressive strength, elastic modulus (E50), microstructure and freeze thaw durability of silty sand subgrade soil stabilized with bentonite magnesium alkalinization. The selected curing temperatures and durations included ambient temperature, 40°C, 60°C and …
has type: Thesis/Dissertation
date issued: 2019-11
is shown at: 10.14288/1.0380924
language: eng
degree discipline: Civil Engineering
provider: Vancouver : University of British Columbia Library
publisher: University of British Columbia
rights: Attribution-NonCommercial-NoDerivatives 4.0 International
rights URI: http://creativecommons.org/licenses/by-nc-nd/4.0/
scholar level: Graduate
type: Text
identifier URI: http://hdl.handle.net/2429/71710