Laboratory Investigation of Deep Soil Mixing for the Improvement of Salt-Cemented Soils

• Published in: Geotechnical and geological engineering Vol. 42; no. 8; pp. 7753 - 7770
• Main Authors: Hammad, Mohammed A., Mohamedzein, Yahia E.-A., Al-Aghbari, Mohammed Y., Al-Nuaimi, Ali S.
• Format: Journal Article
• Language: English
• Published: Cham Springer International Publishing 01-11-2024; Springer Nature B.V
• Subjects: Bearing capacity; Chemical interactions; Civil Engineering; Column strength; Compressibility; Deep foundations; Design optimization; Earth and Environmental Science; Earth Sciences; Effectiveness; Geotechnical Engineering & Applied Earth Sciences; Hydrogeology; Image enhancement; Instrumentation; Measuring instruments; Moisture content; Original Paper; Salts; Scale models; Scanning electron microscopy; Settling; Shear strength; Soil; Soil bearing capacity; Soil chemistry; Soil compressibility; Soil conditions; Soil improvement; Soil investigations; Soil mixing; Soil settlement; Soil strength; Soil stresses; Soil structure; Soil water; Soils; Structural stability; Terrestrial Pollution; Waste Management/Waste Technology; Water content; Settlement; Salt-cemented Soil; Bearing capacity; Salt content; Total water content; Deep soil mixing
• ISSN: 0960-3182; 1573-1529
• DOI: 10.1007/s10706-024-02949-4

Salt-cemented soils are problematic soils and known for high compressibility and inadequate shear strength, pose significant challenges to structural stability. This paper investigates stabilizing such soils using deep soil mixing (DSM) technique, a cost-effective alternative to traditional deep foundations. A series of laboratory-scale models were employed to evaluate the performance of stabilized salt-cemented soils under various soil states. A specially designed deep soil mixing apparatus was employed to prepare a DSM column within a steel tank, with instrumentation for measuring induced stresses and settlements under various soil conditions. The results demonstrated that DSM significantly enhances bearing capacity and reduces settlement, with effectiveness influenced by factors such as salt content and total water content (TWC). The TWC, which includes initial water content and water/binder ratio, is critical for mixing efficiency and should be critically designed prior to the treatment to achieve the maximum possible improvement. TWC is equal to 41% contributing to the highest column strength and hence the ultimate bearing capacity. Scanning electron microscope images revealed denser structures in treated columns, indicating improved soil contact and strength. While the ultimate bearing capacity decreases with higher salt content, improvements ranged from 125 to 150% depending on salt concentration. Chemical interactions between soil salts and cementitious materials were also found to enhance shear strength over time. The study’s findings provide valuable guidelines for optimizing DSM treatment parameters to effectively stabilize salt-cemented soils. The developed models were validated against past design equations and real-world tests, confirming their reliability and effectiveness.