Strength reduction mechanism of cement-treated soil under seawater environment

IF 3.3 2区工程技术 Q2 ENGINEERING, GEOLOGICAL

Soils and Foundations Pub Date : 2024-02-01 DOI:10.1016/j.sandf.2024.101425

Hiroyuki Hara, Kenshi Ikeda, Norimasa Yoshimoto

{"title":"Strength reduction mechanism of cement-treated soil under seawater environment","authors":"Hiroyuki Hara, Kenshi Ikeda, Norimasa Yoshimoto","doi":"10.1016/j.sandf.2024.101425","DOIUrl":null,"url":null,"abstract":"<div><p>Improving soft grounds with cement or lime is commonly used to increase their strength and deformation characteristics. However, the properties of cement/lime-treated soil deteriorate in seawater because magnesium salts accelerate calcium leaching. In this study, changes in the unconfined compressive strength of cement-treated soil samples with various water contents, amounts of added cement, and curing times were investigated after immersion in a highly concentrated Mg solution. Subsequently, a thermogravimetric-differential thermal analysis and scanning electron microscopy were used to determine the strength reduction mechanism based on the changes in the hydrate composition as the cement-treated soil deteriorated. The results indicate that the cement-treated soil lost more than 80% of its strength after immersion in the Mg solution. The initial conditions strongly influenced the strength of the deteriorated soil, and higher strength was observed in the samples with larger amounts of added cement and longer curing times. Furthermore, calcium silicate hydrate (C-S-H) and ettringite were not present in the deteriorated soil, implying the presence of magnesium silicate hydrate (M-S-H). Therefore, it was postulated that the loss in strength of the cement-treated soil in a seawater environment was caused by the transformation of C-S-H to M-S-H.</p></div>","PeriodicalId":21857,"journal":{"name":"Soils and Foundations","volume":"64 1","pages":"Article 101425"},"PeriodicalIF":3.3000,"publicationDate":"2024-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.sciencedirect.com/science/article/pii/S0038080624000039/pdfft?md5=9b81066eeef3cacb7c1fcb7b0c3cf7f4&pid=1-s2.0-S0038080624000039-main.pdf","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Soils and Foundations","FirstCategoryId":"5","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0038080624000039","RegionNum":2,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q2","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}

引用次数: 0

Abstract

Improving soft grounds with cement or lime is commonly used to increase their strength and deformation characteristics. However, the properties of cement/lime-treated soil deteriorate in seawater because magnesium salts accelerate calcium leaching. In this study, changes in the unconfined compressive strength of cement-treated soil samples with various water contents, amounts of added cement, and curing times were investigated after immersion in a highly concentrated Mg solution. Subsequently, a thermogravimetric-differential thermal analysis and scanning electron microscopy were used to determine the strength reduction mechanism based on the changes in the hydrate composition as the cement-treated soil deteriorated. The results indicate that the cement-treated soil lost more than 80% of its strength after immersion in the Mg solution. The initial conditions strongly influenced the strength of the deteriorated soil, and higher strength was observed in the samples with larger amounts of added cement and longer curing times. Furthermore, calcium silicate hydrate (C-S-H) and ettringite were not present in the deteriorated soil, implying the presence of magnesium silicate hydrate (M-S-H). Therefore, it was postulated that the loss in strength of the cement-treated soil in a seawater environment was caused by the transformation of C-S-H to M-S-H.

查看原文本刊更多论文

海水环境下水泥处理土壤的强度降低机制

用水泥或石灰改良软土地通常是为了提高其强度和变形特性。然而，水泥/石灰处理过的土壤在海水中的特性会恶化，因为镁盐会加速钙的浸出。在本研究中，研究了不同含水量、水泥添加量和固化时间的水泥处理土壤样本在浸泡在高浓度镁溶液中后的无压抗压强度变化。随后，使用热重-差热分析和扫描电子显微镜，根据水泥处理土壤恶化时水合物成分的变化确定强度降低的机制。结果表明，水泥处理过的土壤在镁溶液中浸泡后强度降低了 80% 以上。初始条件对劣化土壤的强度有很大影响，添加水泥量越大、固化时间越长的样品强度越高。此外，劣化土壤中不存在硅酸钙水合物（C-S-H）和埃特林岩，这意味着存在硅酸镁水合物（M-S-H）。因此，推测水泥处理过的土壤在海水环境中强度下降的原因是 C-S-H 转化为 M-S-H。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

求助全文

约1分钟内获得全文求助全文

来源期刊

Soils and Foundations 工程技术-地球科学综合

CiteScore

6.40

自引率

8.10%

发文量

审稿时长

5 months

期刊介绍： Soils and Foundations is one of the leading journals in the field of soil mechanics and geotechnical engineering. It is the official journal of the Japanese Geotechnical Society (JGS)., The journal publishes a variety of original research paper, technical reports, technical notes, as well as the state-of-the-art reports upon invitation by the Editor, in the fields of soil and rock mechanics, geotechnical engineering, and environmental geotechnics. Since the publication of Volume 1, No.1 issue in June 1960, Soils and Foundations will celebrate the 60th anniversary in the year of 2020. Soils and Foundations welcomes theoretical as well as practical work associated with the aforementioned field(s). Case studies that describe the original and interdisciplinary work applicable to geotechnical engineering are particularly encouraged. Discussions to each of the published articles are also welcomed in order to provide an avenue in which opinions of peers may be fed back or exchanged. In providing latest expertise on a specific topic, one issue out of six per year on average was allocated to include selected papers from the International Symposia which were held in Japan as well as overseas.