Influence of nano-SiO2 on geotechnical properties of fine soils subjected to freeze-thaw cycles

• Published in: Cold regions science and technology 2019-05, Vol.161, p.129-136
• Main Authors: Kalhor, Amir, Ghazavi, Mahmoud, Roustaei, Mahya, Mirhosseini, S.M.
• Format: Article
• Language: English
• Subjects: Fine-grained soils; Freeze-thaw cycles; Nano-SiO2; Soil improvement; Unconfined compression strength
• ISSN: 0165-232X; 1872-7441
• DOI: 10.1016/j.coldregions.2019.03.011

Nanoparticles have been recently used in various applications due to their availability and justified costs. Thus, the effects of such materials on physical, chemical and mechanical properties of soils are of great interest to investigate. In this research, the effects of freeze-thaw cycles on specimens stabilized by nanoparticles are investigated. For this purpose, nano-SiO2 is used as an additive to fine-grained soils subjected up to nine freeze-thaw cycles. Laboratory tests including standard Proctor, Atterberg limits and unconfined compression tests (UCTs) have been conducted on a clayey soil mixed with nano-SiO2. The samples were also cured for up to 42 days. The results show that when the clayey soil is stabilized with nano-SiO2, the optimum moisture content, liquid limit (LL) and plastic limit (PL) increase, while the maximum dry unit weight and PI decrease. An increase of nano-SiO2 up to an optimal of 2% and curing time up to 42 days improves the unconfined compressive strength (UCS) by about 63%. In addition, the increase in nano-SiO2 leads to brittle behavior of the specimens. Moreover, the freeze-thaw cycle decreases the UCS of the specimens. However, a descending trend for strength is observed in nano-SiO2 stabilized specimens compared with untreated clay. After nine freeze-thaw cycles, the strength of untreated and treated soil with 2% nano-SiO2 decrease by about 64% and 42%, respectively. Also, with increasing the freeze-thaw cycles, stabilized specimens exhibit more ductility. •With increasing nano-SiO2 to the soil, its maximum dry unit weight decreases and the optimum moisture content increases.•PL, LL and PI values increase with increasing nano-SiO2.•The clay stabilized with 1%, 2% and 3% nano-SiO2 and allowing 42 curing days results in increasing the UCS values by about 14%, 63%, and 29%, respectively.•Stabilization of the clay with nano-SiO2 causes a brittle behavior in stress-strain curves.•Increasing the freeze-thaw cycles decreases the UCS values of stabilized/non-stabilized specimens. This decreases continues to the 6th and 7th cycle and then reaches almost a balance.