Deteriorated characteristics, elemental zonation, and phase changes in the surface of cemented soil exposed to marine environment

• Published in: Acta geotechnica Vol. 20; no. 3; pp. 1157 - 1176
• Main Authors: Wu, Yalei, Yang, Junjie, Yan, Nan, Bai, Xiaoyu
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.03.2025; Springer Nature B.V
• Subjects: Calcium ions; Chemical analysis; Complex Fluids and Microfluidics; Cone penetration tests; Corrosion; Corrosion prevention; Corrosion products; Deterioration; Electron microscopy; Engineering; Enrichment; Exposure; Foundations; Geoengineering; Geotechnical Engineering & Applied Earth Sciences; Hydraulics; Ion concentration; Ions; Leaching; Magnesium; Marine corrosion; Marine environment; Phase changes; Research Paper; Scanning electron microscopy; Seawater; Soft and Granular Matter; Soil; Soil Science & Conservation; Soil testing; Soils; Solid Mechanics; Spectroscopy; Strength; Structural safety; Surface layers; Transition layers; Water analysis; X-ray diffraction; Zonation; Marine corrosion environment; Elemental zonation; Cemented soil; Phase changes; Micro-cone penetration test
• ISSN: 1861-1125; 1861-1133
• DOI: 10.1007/s11440-024-02428-3

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 2+ and SO 4 2− were mainly enriched in the deteriorated zone, and Cl − could invade and enrich in the undeteriorated zone. Besides, the leaching of Ca 2+ 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. Graphical abstract