Bakhshandeh Fatemeh, Noorzad Reza, Ta'negonbadi Bahram
Faculty of Civil Engineering, Babol Noshirvani University of Technology, Babol, Iran.
Department of Civil Engineering, Faculty of Engineering, Bojnord University, Bojnord, Iran.
Sci Rep. 2025 Aug 16;15(1):30032. doi: 10.1038/s41598-025-15965-y.
Collapsible soils pose significant geotechnical challenges due to their tendency to exhibit high strength under natural moisture conditions but undergo substantial settlement upon wetting. To address this issue, various stabilizing agents, including lime, cement, silicates, resins, and acids, have been explored. This study investigates the effectiveness of colloidal silica (CS), a low-viscosity solution capable of forming a gel, as a stabilizing agent. Its unique properties enable it to be injected into or mixed directly with soil, offering versatility in application. The behavior of CS-stabilized collapsible soil was evaluated through collapse potential and unconfined compressive strength (UCS) tests. Scanning electron microscopy (SEM) was also conducted to analyze microstructural changes in untreated and CS-treated soils. Colloidal silica was added at concentrations of 3, 5, 7, and 10% by weight of dry soil, with curing times of one, 7, 14, and 28 days. Collapse potential tests were performed at relative compactions of 80 and 85%, while UCS tests used a relative compaction of 95%. Results indicated that colloidal silica significantly reduced soil collapsibility while enhancing stiffness and UCS without inducing brittleness. A 5% CS concentration was optimal, reducing collapsibility from severe to negligible. Increased relative compaction (80 to 85%) further decreased collapsibility, whereas higher inundation stress increased it. These improvements are attributed to pore filling by colloidal silica, which enhances inter-particle bonding and structural integrity.
湿陷性土带来了重大的岩土工程挑战，因为它们在天然湿度条件下往往具有较高的强度，但在浸湿后会发生大量沉降。为了解决这个问题，人们探索了各种稳定剂，包括石灰、水泥、硅酸盐、树脂和酸。本研究调查了胶体二氧化硅（CS）作为一种稳定剂的有效性，CS是一种能够形成凝胶的低粘度溶液。其独特的性能使其能够注入土壤或直接与土壤混合，在应用上具有多样性。通过湿陷性潜力和无侧限抗压强度（UCS）试验评估了CS稳定的湿陷性土的性能。还进行了扫描电子显微镜（SEM）分析未处理和CS处理土壤的微观结构变化。以干土重量的3%、5%、7%和10%的浓度添加胶体二氧化硅，养护时间为1天、7天、14天和28天。在相对压实度为80%和85%的情况下进行湿陷性潜力试验，而UCS试验使用的相对压实度为95%。结果表明，胶体二氧化硅显著降低了土壤的湿陷性，同时提高了刚度和UCS，而不会导致脆性。5%的CS浓度是最佳的，将湿陷性从严重降低到可忽略不计。相对压实度的增加（80%至85%）进一步降低了湿陷性，而更高的淹没应力则增加了湿陷性。这些改善归因于胶体二氧化硅填充孔隙，从而增强了颗粒间的粘结和结构完整性。
