{"title":"Deteriorated characteristics, elemental zonation, and phase changes in the surface of cemented soil exposed to marine environment","authors":"Yalei Wu, Junjie Yang, Nan Yan, Xiaoyu Bai","doi":"10.1007/s11440-024-02428-3","DOIUrl":null,"url":null,"abstract":"<div><p>The deterioration issues of surface strength reduction occur in cemented soil exposed to marine corrosion environment for long-term, which seriously affects the durability and safety of the structure. Therefore, it is urgent to reveal the tempo-spatial deterioration mechanisms of cemented soil, which can provide a theoretical basis for practical anti-deterioration measures. In this study, the micro-cone penetration test of cemented soil exposed to seawater was conducted, and the ion profiles, pH, X-ray diffraction (XRD), and scanning electron microscopy with energy disperse spectroscopy (SEM–EDS) tests of different slice layers from the exposed surface were performed. The results show that the deteriorated cemented soil along the erosion direction can be classified into completely deteriorated layer with zero-strength, deteriorated transition layer with only about 10% strength remaining, and an undeteriorated zone with no strength reduction. The depth of the deteriorated zone increased with corrosion time and decreased with cement content, but the strength reduction was not affected. The micro-cone penetration, ion concentration, pH, XRD and SEM–EDS results illustrated that the essential nature of deterioration of cemented soils is the tempo-spatial evolution of corrosive ions enriched by corrosion reactions and gradually induced the phase change of hydration products into non-cementitious or secondary expansion products, which ultimately leads to the strength reduction in surface layers. Moreover, Mg<sup>2+</sup> and SO<sub>4</sub><sup>2−</sup> were mainly enriched in the deteriorated zone, and Cl<sup>−</sup> could invade and enrich in the undeteriorated zone. Besides, the leaching of Ca<sup>2+</sup> and OH<sup>−</sup> was associated with the invasion of all these corrosive ions. This study contributes to the deterioration mechanism of cemented soil and provides useful reference for the development of seawater anti-corrosion binder.</p><h3>Graphical abstract</h3><div><figure><div><div><picture><source><img></source></picture></div></div></figure></div></div>","PeriodicalId":49308,"journal":{"name":"Acta Geotechnica","volume":"20 3","pages":"1157 - 1176"},"PeriodicalIF":5.6000,"publicationDate":"2024-10-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"Acta Geotechnica","FirstCategoryId":"5","ListUrlMain":"https://link.springer.com/article/10.1007/s11440-024-02428-3","RegionNum":1,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q1","JCRName":"ENGINEERING, GEOLOGICAL","Score":null,"Total":0}
引用次数: 0
Abstract
The deterioration issues of surface strength reduction occur in cemented soil exposed to marine corrosion environment for long-term, which seriously affects the durability and safety of the structure. Therefore, it is urgent to reveal the tempo-spatial deterioration mechanisms of cemented soil, which can provide a theoretical basis for practical anti-deterioration measures. In this study, the micro-cone penetration test of cemented soil exposed to seawater was conducted, and the ion profiles, pH, X-ray diffraction (XRD), and scanning electron microscopy with energy disperse spectroscopy (SEM–EDS) tests of different slice layers from the exposed surface were performed. The results show that the deteriorated cemented soil along the erosion direction can be classified into completely deteriorated layer with zero-strength, deteriorated transition layer with only about 10% strength remaining, and an undeteriorated zone with no strength reduction. The depth of the deteriorated zone increased with corrosion time and decreased with cement content, but the strength reduction was not affected. The micro-cone penetration, ion concentration, pH, XRD and SEM–EDS results illustrated that the essential nature of deterioration of cemented soils is the tempo-spatial evolution of corrosive ions enriched by corrosion reactions and gradually induced the phase change of hydration products into non-cementitious or secondary expansion products, which ultimately leads to the strength reduction in surface layers. Moreover, Mg2+ and SO42− were mainly enriched in the deteriorated zone, and Cl− could invade and enrich in the undeteriorated zone. Besides, the leaching of Ca2+ and OH− was associated with the invasion of all these corrosive ions. This study contributes to the deterioration mechanism of cemented soil and provides useful reference for the development of seawater anti-corrosion binder.
期刊介绍：
Acta Geotechnica is an international journal devoted to the publication and dissemination of basic and applied research in geoengineering – an interdisciplinary field dealing with geomaterials such as soils and rocks. Coverage emphasizes the interplay between geomechanical models and their engineering applications. The journal presents original research papers on fundamental concepts in geomechanics and their novel applications in geoengineering based on experimental, analytical and/or numerical approaches. The main purpose of the journal is to foster understanding of the fundamental mechanisms behind the phenomena and processes in geomaterials, from kilometer-scale problems as they occur in geoscience, and down to the nano-scale, with their potential impact on geoengineering. The journal strives to report and archive progress in the field in a timely manner, presenting research papers, review articles, short notes and letters to the editors.
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