DETERMINATION OF APPARENT CHLORIDE DIFFUSION COEFFICIENT FOR SELF COMPACTING CONCRETE CONTAINING NANO SILICA UNDER EFFECT OF SULFATE ATTACK

The objective of this work is devoted to determine the apparent chloride diffusion coefficient of self compacting concrete (SCC) with Nano Silica which is subjected to severe saline conditions contain sulfates and chlorides at concentrations similar to those existing in soils and ground water of the middle and southern parts of Iraq. Four basic mixes of SCC were performed with and without addition of Nano Silica, and with two types of cement (ordinary Portland cement and sulfate resistance Portland cement). The workability properties of mixes were evaluated by fresh tests such as slump-flow test, T50cm, L-box and V-funnel tests. The apparent chloride diffusion coefficient was determined at90 and 180 days. Test results exhibited that the presence of Nano Silica in concrete decreases the apparent chloride diffusion coefficient at age of 180 days which was ranged between (50.83-54.40)% measured relative to its reference mixes without Nano silica addition. Also, the results revealed that SRPC specimens have higher chloride content than OPC mixes especially at 90 days. while at 180 days, SRPC specimens have lower chloride content than OPC specimens.