{"title":"利用二氧化碳固化生物炭稳定低排放软粘土的可行性","authors":"","doi":"10.1016/j.trgeo.2024.101370","DOIUrl":null,"url":null,"abstract":"<div><p>Use of traditional lime-cement binders on stabilizing soft sensitive clays pose a significant challenge for the construction sector to reach Finland’s carbon neutrality goals by 2030. Traditional stabilization recipes consisting of cement as binders contributing significantly to CO<sub>2</sub> emissions (<span><math><mo>≅</mo></math></span> 500 kg CO<sub>2</sub> eq./ton in deep mixing alone). This laboratory study explores the feasibility of achieving near carbon-negative stabilization of soft clay leveraging accelerated CO<sub>2</sub> curing (ACC) in biochar (BC) enhanced cementitious composites. BC, a by-product of the biofuel industry, is used as partial replacement of cement (0 %, 10 %, and 50 % of binder) in developing precast cementitious piles. One non-carbonated treatment and two ACC treatments are employed to assess their uniaxial compressive strength, thermogravimetric properties and CO<sub>2</sub> sequestration capacity. The results demonstrate that synergistic effects of using BC with ACC not only enhances the compressive strength of the composites but also promotes CO<sub>2</sub> uptake due to formation of stable carbonates. BC due to its surface functional groups, honeycomb porous structure, and hydrophilicity facilitated uniform CO<sub>2</sub> diffusion in the clay matrix and likely improved internal curing. In ACC treated composites, the replacement of 50 % of cement with BC resulted in sufficient load-bearing capacity (≥50 kPa as per Finnish Guidelines) for both shallow and deep clay layers, making a suitable subgrade media for many types of geotechnical applications. The measured bound CO<sub>2</sub> increased gravimetrically from 2 % to 41 % when cement was partially replaced by BC. In case of non-carbonated samples, 10 % partial replacement of BC provided high strength (<span><math><mrow><mo>≥</mo><mn>200</mn><mspace></mspace><mi>k</mi><mi>P</mi><mi>a</mi></mrow></math></span>). Life Cycle Assessment (LCA) of a case study of utilizing BC stabilized clay in deep mixing operations can potentially reduce net carbon emissions to −50 kg CO<sub>2</sub> eq./ton.</p></div>","PeriodicalId":56013,"journal":{"name":"Transportation Geotechnics","volume":null,"pages":null},"PeriodicalIF":4.9000,"publicationDate":"2024-09-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S2214391224001910/pdfft?md5=9d674a13669b692ee227a0bee58a1db6&pid=1-s2.0-S2214391224001910-main.pdf","citationCount":"0","resultStr":"{\"title\":\"Feasibility of biochar for low-emission soft clay stabilization using CO2 curing\",\"authors\":\"\",\"doi\":\"10.1016/j.trgeo.2024.101370\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>Use of traditional lime-cement binders on stabilizing soft sensitive clays pose a significant challenge for the construction sector to reach Finland’s carbon neutrality goals by 2030. Traditional stabilization recipes consisting of cement as binders contributing significantly to CO<sub>2</sub> emissions (<span><math><mo>≅</mo></math></span> 500 kg CO<sub>2</sub> eq./ton in deep mixing alone). This laboratory study explores the feasibility of achieving near carbon-negative stabilization of soft clay leveraging accelerated CO<sub>2</sub> curing (ACC) in biochar (BC) enhanced cementitious composites. BC, a by-product of the biofuel industry, is used as partial replacement of cement (0 %, 10 %, and 50 % of binder) in developing precast cementitious piles. One non-carbonated treatment and two ACC treatments are employed to assess their uniaxial compressive strength, thermogravimetric properties and CO<sub>2</sub> sequestration capacity. The results demonstrate that synergistic effects of using BC with ACC not only enhances the compressive strength of the composites but also promotes CO<sub>2</sub> uptake due to formation of stable carbonates. BC due to its surface functional groups, honeycomb porous structure, and hydrophilicity facilitated uniform CO<sub>2</sub> diffusion in the clay matrix and likely improved internal curing. In ACC treated composites, the replacement of 50 % of cement with BC resulted in sufficient load-bearing capacity (≥50 kPa as per Finnish Guidelines) for both shallow and deep clay layers, making a suitable subgrade media for many types of geotechnical applications. The measured bound CO<sub>2</sub> increased gravimetrically from 2 % to 41 % when cement was partially replaced by BC. In case of non-carbonated samples, 10 % partial replacement of BC provided high strength (<span><math><mrow><mo>≥</mo><mn>200</mn><mspace></mspace><mi>k</mi><mi>P</mi><mi>a</mi></mrow></math></span>). Life Cycle Assessment (LCA) of a case study of utilizing BC stabilized clay in deep mixing operations can potentially reduce net carbon emissions to −50 kg CO<sub>2</sub> eq./ton.</p></div>\",\"PeriodicalId\":56013,\"journal\":{\"name\":\"Transportation Geotechnics\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":4.9000,\"publicationDate\":\"2024-09-10\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://www.sciencedirect.com/science/article/pii/S2214391224001910/pdfft?md5=9d674a13669b692ee227a0bee58a1db6&pid=1-s2.0-S2214391224001910-main.pdf\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Transportation Geotechnics\",\"FirstCategoryId\":\"5\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S2214391224001910\",\"RegionNum\":2,\"RegionCategory\":\"工程技术\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q1\",\"JCRName\":\"ENGINEERING, CIVIL\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Transportation Geotechnics","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S2214391224001910","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, CIVIL","Score":null,"Total":0}
引用次数: 0
摘要
使用传统的石灰-水泥粘结剂来稳定敏感软粘土,对建筑行业实现芬兰 2030 年碳中和目标构成了重大挑战。以水泥为粘结剂的传统稳定配方会产生大量二氧化碳排放(仅深度搅拌就会产生 500 千克二氧化碳当量/吨)。本实验室研究探讨了利用生物炭(BC)增强水泥基复合材料中的二氧化碳加速固化(ACC)实现软粘土近乎负碳稳定化的可行性。生物炭是生物燃料工业的副产品,在开发水泥基预制桩时可部分替代水泥(粘结剂含量分别为 0%、10% 和 50%)。采用了一种非碳化处理方法和两种碳酸钙处理方法来评估它们的单轴抗压强度、热重特性和二氧化碳封存能力。结果表明,使用 BC 和 ACC 的协同效应不仅能提高复合材料的抗压强度,还能通过形成稳定的碳酸盐促进二氧化碳的吸收。萃取物因其表面官能团、蜂窝状多孔结构和亲水性,促进了二氧化碳在粘土基质中的均匀扩散,并有可能改善内部固化。在经 ACC 处理的复合材料中,用 BC 替代 50% 的水泥后,浅层和深层粘土层都具有足够的承载能力(根据芬兰准则,承载能力≥50 kPa),适合作为多种岩土工程应用的基层介质。当水泥部分被 BC 取代时,测得的结合态 CO2 从 2% 增加到 41%。在非碳化样品中,部分替代 10% BC 可提供高强度(≥200kPa)。在深层搅拌操作中使用萃取稳定粘土的生命周期评估(LCA)案例研究有可能将净碳排放量减少到-50 千克二氧化碳当量/吨。
Feasibility of biochar for low-emission soft clay stabilization using CO2 curing
Use of traditional lime-cement binders on stabilizing soft sensitive clays pose a significant challenge for the construction sector to reach Finland’s carbon neutrality goals by 2030. Traditional stabilization recipes consisting of cement as binders contributing significantly to CO2 emissions ( 500 kg CO2 eq./ton in deep mixing alone). This laboratory study explores the feasibility of achieving near carbon-negative stabilization of soft clay leveraging accelerated CO2 curing (ACC) in biochar (BC) enhanced cementitious composites. BC, a by-product of the biofuel industry, is used as partial replacement of cement (0 %, 10 %, and 50 % of binder) in developing precast cementitious piles. One non-carbonated treatment and two ACC treatments are employed to assess their uniaxial compressive strength, thermogravimetric properties and CO2 sequestration capacity. The results demonstrate that synergistic effects of using BC with ACC not only enhances the compressive strength of the composites but also promotes CO2 uptake due to formation of stable carbonates. BC due to its surface functional groups, honeycomb porous structure, and hydrophilicity facilitated uniform CO2 diffusion in the clay matrix and likely improved internal curing. In ACC treated composites, the replacement of 50 % of cement with BC resulted in sufficient load-bearing capacity (≥50 kPa as per Finnish Guidelines) for both shallow and deep clay layers, making a suitable subgrade media for many types of geotechnical applications. The measured bound CO2 increased gravimetrically from 2 % to 41 % when cement was partially replaced by BC. In case of non-carbonated samples, 10 % partial replacement of BC provided high strength (). Life Cycle Assessment (LCA) of a case study of utilizing BC stabilized clay in deep mixing operations can potentially reduce net carbon emissions to −50 kg CO2 eq./ton.
期刊介绍:
Transportation Geotechnics is a journal dedicated to publishing high-quality, theoretical, and applied papers that cover all facets of geotechnics for transportation infrastructure such as roads, highways, railways, underground railways, airfields, and waterways. The journal places a special emphasis on case studies that present original work relevant to the sustainable construction of transportation infrastructure. The scope of topics it addresses includes the geotechnical properties of geomaterials for sustainable and rational design and construction, the behavior of compacted and stabilized geomaterials, the use of geosynthetics and reinforcement in constructed layers and interlayers, ground improvement and slope stability for transportation infrastructures, compaction technology and management, maintenance technology, the impact of climate, embankments for highways and high-speed trains, transition zones, dredging, underwater geotechnics for infrastructure purposes, and the modeling of multi-layered structures and supporting ground under dynamic and repeated loads.