DEVELOPMENT OF SUSTAINABLE STRUCTURAL MATERIALS USING BASALT FIBER AND AGRICULTURAL WASTE IN CEMENTITIOUS SYSTEM FOR GROUND IMPROVEMENT

• 資料種別: 博士論文
• タイトル: DEVELOPMENT OF SUSTAINABLE STRUCTURAL MATERIALS USING BASALT FIBER AND AGRICULTURAL WASTE IN CEMENTITIOUS SYSTEM FOR GROUND IMPROVEMENT
• 著者・編者: OWINO, OTIENO ALEX
• 著者標目: OWINO, OTIENO ALEX
• 出版事項: 三重大学
• 出版年月日等: 2023-09-25
• 出版年（W3CDTF）: 2023-09-25
• 並列タイトル等: セメント系における玄武岩繊維と農業廃棄物を利用した持続可能な地盤改良用構造材料の開発
• 授与機関名: 三重大学
• 授与年月日: 2023-09-25
• 授与年月日（W3CDTF）: 2023-09-25
• 報告番号: 甲学術第2221号
• 学位: 博士(学術)
• 本文の言語コード: eng
• 対象利用者: 一般
• 一般注記: application/pdf; With the increase in the built environment due to urbanization and industrialization, there is a rising demand for infrastructure development in marginalized areas with weak expansive soils, which are considered unsuitable. Expansive soils have been analyzed to possess weak shear strength and high compressibility and pose numerous challenges to civil and geotechnical engineers when constructing any engineering structures. The instability of the expansive soil is due to the high clay contents, which tend to shrink or expand when subjected to moisture content variation. Building on expansive soils can lead to considerable damage to foundations, embankments, and pavements, increasing the cost of constructing durable and safe structures.Stabilizing and reinforcing the expansive soils to improve their geotechnical properties is vital to curb these challenges. Conventionally, the addition of additives such as cement, lime, and limecement mixtures has been practiced extensively. However, the over-dependence on cement and lime has proven to degrade the environment, raising environmental concerns such as contributing to 8 to 10 percent of global anthropogenic CO2 emission from the 4.1 billion metric tons produced yearly. In addition to the emissions of CO2, the production of cement and lime can also lead to the depletion of natural resources. Cement production requires large amounts of raw materials such as limestone, clay, and sand. These resources are finite and can become depleted if not managed sustainably. Moreover, mining these raw materials can negatively impact the environment as their manufacture involves the crushing and grinding of raw materials, which can produce large amounts of dust that can negatively impact human health and local ecosystems.In addition to the environmental drawbacks, cement and lime are susceptible to high plastic shrinkage and cracking, affecting the mechanical strength of the stabilized soil. To reduce these environmental concerns and enhance the geotechnical properties of expansive soils, the partial replacement of cement and lime with pozzolanic additives such as rice husk ash (RHA) is gaining research attention. The potential use of RHA in soil stabilization can be attributed to; the abundance of rice husks generated worldwide from rice processing and particularly the presence of highly active amorphous silica (SiO2) produced during the production process of rice husk ash. However, during the soil stabilization phase, the pozzolanic reactions between the additives and the soil form cementitious systems that need further reinforcements to avoid cracking and excessive settlement problems when subjected to extensive loads. Recently, fibers have been used with cementitious additives to arrest the formation of weak planes in the stabilized soil and to influence the strength of the stabilized composite material. However, in the available literature, most research articles are limited to the reinforcement material used, the soil tested, and the type of stabilizing agent used. To date, few pieces of research have been carried out on expansive soils with no scientific studies on the combined action of RHA, minimal cement dosages, and basalt fiber, particularly its effect on consolidation settlement, volume change, shear strength, bearing capacity, microstructural development, and ultimate permeability. In this context, the present study aimed to investigate the influences on bearing capacity, shear strength, consolidation coefficients, permeability, and micro and macrostructure of different specified specimen combinations of stabilized and reinforced expansive soils. Each specified specimen combination constituted a mixture of varying basalt fiber lengths and varied dosages of RHA-cement mixtures in their proposed proportions. In addition, the investigation proposed a material combination scheme with superior properties that could be used as a fill or subbase material for engineering structures such as embankments, pavements, and foundations.In this research, a series of Oedometer tests, Compaction tests, Consolidated-drained (CD) Triaxial tests, Unconfined Compression Strength tests (UCS) tests, Constant head permeability tests, and microstructural analysis tests (SEM and XRD) were conducted on expansive soil reinforced with different basalt fiber lengths (3mm, 6mm, and 12mm) and stabilized with RHA (5%,10%, and 15%)-cement (3%) mixtures in their specified combinations. Furthermore, scanning electron microscopy (SEM) tests and X-ray diffraction (XRD) analysis were conducted to examine the microstructural modifications and chemical composition developments within the stabilized and reinforced soil composite. The results were presented graphically with correlation equations and pictorial forms to provide additional data and to act as a benchmark for providing solutions to challenges encountered by civil, geotechnical, and geo-environmental engineers working with the new composite material.Based on the experimental results obtained in this study, it was concluded that adding RHA, minimal dosages of cement, and basalt fiber reinforcements to expansive soil significantly improved its compatibility, bearing capacity, and shear strength, reduced the rate of consolidation settlements, and enhanced the microstructure development. The increased strength enhanced its stability and suitability when used in geotechnical engineering applications.; 本文/Soil Resources Engineering Laboratory Department of Environmental Science and Technology Graduate School of Bioresources Mie University Mie, Japan; 266p
• 国立国会図書館永続的識別子: info:ndljp/pid/13122610; https://dl.ndl.go.jp/pid/13122610
• コレクション（共通）: 障害者向け資料
• コレクション（障害者向け資料：レベル1）: テキストデータ
• コレクション（個別）: 国立国会図書館デジタルコレクション > デジタル化資料 > 博士論文; https://dl.ndl.go.jp/collections/A00014
• 収集根拠: 博士論文（自動収集）
• 受理日（W3CDTF）: 2023-12-15T22:13:25+09:00
• 記録形式（IMT）: application/pdf
• オンライン閲覧公開範囲: 国立国会図書館内限定公開
• デジタル化資料送信: 図書館・個人送信対象外
• 遠隔複写可否（NDL）: 可
• 掲載誌（URI）: http://hdl.handle.net/10076/0002000163; https://mie-u.repo.nii.ac.jp/records/2000163
• 連携機関・データベース: 国立国会図書館 : 国立国会図書館デジタルコレクション; https://dl.ndl.go.jp