AN INVESTIGATION ON THE EFFECTS OF ADDING NANO-SIO2 PARTICLES WITH DIFFERENT SPECIFIC SURFACE AREAS ON THE PHYSICAL AND MECHANICAL PARAMETERS OF SOIL-CEMENT MATERIALS

SoilcementisamixtureofPortlandcement,soilandwater, inwhichhydrationofcementandcompactioncauses the material's constituents to bond together, making a dense and durable composition with low permeability and abrasion resistant. According to the denition of ACI 116R, soil-cement is a mixture of soil and a certain amount of cement and water which has been compacted to a high density. A more comprehensive denition has been provided in ACI 230 IR, which denes the soil-cement as a hard material with specic engineering properties produced by mixing, compaction and curing of soil, aggregate, Portland cement, additives and water. Alltypesofsoilscanbeusedinsoil-cementconstruction, except the organic and plastic soils and reactive sands. The most ecient soils for soil cement are those containing 5 to 35% of nes passing sieve 200. However, the soils containing more than 2% of organic materials are strictly unacceptable. Soil-cement application in dams and pavements construction has grown rapidly in recent years. These mixtures are similar to concrete, the main dierence being the type and size of aggregate particles used. Soil-cement is principally made of round natural nes, while concrete is made of aggregates. Because most of the recent researches are focused on the addition of nano-SiO2 on concrete, in this paper, we decided to use nano-SiO2 particles in soil-cement and observe the out coming eects. Since there are no particles passing sieve 200 in concrete and this restriction does not apply to soil-cements, some tests were carried out on thenano-SiO2 soil-cement matrix because of the meaningful dierence between concrete and soil-cement. The test procedure consists of moisture-dry density, unconned compressive test, and hydraulic conductivity. In these tests, silica fume (with specic surface area of 21m2=g) and, nano-SiO2 (with specic surface areas of 200 and 380m2=g) were added to soil-cement. The results show that adding certain amounts of nano-SiO2 particles to soil-cement matrix can improve compressive strength and reduce impermeability and speed hydra tion reactionsin the matrix in the presence of nano -SiO2 particles.