Effect of Nanosilica on The permeability of Self Compacting Concrete in Sulfate Environment

Concrete is one of the most important structural materials which is produced from proportional mixture of cement, aggregates, water and admixtures. Compaction of the concrete is one of the factors that make it difficult to use, particularly in the structures with high reinforcement steel bars. In cases such as foundation of bridges, bottom of the columns of skyscrapers and ets, vibration of concrete for compaction is almost impossible. To solve this problem we can use self-compacting concrete which causes complete compaction and also increases casting velocity. This kind of concrete is produced with superplasticizer and other admixtures. This Article examines the effect of the addition of nanosilica on mechanical properties and Durability parameters self-compacting concrete in sulfate destructive environment. For this purpose, in laboratory studies we have used some tests such as compressive strength and permeability. The results show that the addition of nanosilica could effect on mechanical properties of self compacting concrete, also increase the durability of concrete against sulfate destructive factor that reduce the compressive strength at later stages. Nanosilica reduces the porosity in hydration cement by filling the pore space between the larger particles at the nano-scale and greatly reduced permeability.