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

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.