University of Tehran Civil Engineering Infrastructures Journal 2322-2093 54 1 2021 06 01 An Investigation on the Effects of Adding Nano-Sio2 Particles and Silica Fume with Different Specific Surface Areas on the Physical and Mechanical Parameters of Soil-Cement Materials 93 109 82157 10.22059/ceij.2021.291231.1619 EN Milad Tajdini Ph.D., Civil Engineering Department, University of Tabriz, Tabriz, Iran Mohammad Mahdi Bargi 1 Ms.C , Department of Civil Engineering, Tehran University, Tehran, Iran. Omid Rasouli Ghahroudi 2 Ms.C Student, Department of Civil Engineering, Shahed University, Tehran, Iran, 0000-0002-5572-2022 Journal Article 2019 10 22 Soil cement is a mixture of Portland cement, soil and water, in which hydration of cement and compaction causes the materials’ constituents to bond together makes a dense and durable composition with low permeability and abrasion resistant. Since most of the recent researches are focused on the addition of nano-SiO₂ on concrete, in this paper it has been attempted to use nano-SiO₂ particles in soil-cement and observe the effects. Due to the fact that in concrete there are no particles passing sieve 200 and this restriction does not apply to soil-cements, some tests were carried out on the nano-SiO₂ + soil-cement matrix because of the meaningful difference between concrete and soil-cement. The test procedure consists of moisture-dry density, unconfined compressive test and hydraulic conductivity. In these tests, silica fume (with specific surface area of 21 m²/g), nano-SiO₂ (with specific surface area of 200 and 380 m²/g) were added to soil-cement. The results show that adding certain amounts of nano-SiO₂ particles to the soil-cement matrix can improve the compressive strength and reduce permeability and speed hydration reactions in the matrix in presence of nano-SiO₂ particles. https://ceij.ut.ac.ir/article_82157_bb9f4e253ad472e59e217b00098ab615.pdf