A new supplementary cementing material called nano silica (NS) has emerged on the market and has attracted many researchers across different fields, mainly owing to its high silicon dioxide (SiO2) content and its nano size particles.  NS reacts with the calcium hydroxide of cement hydration and forms calcium-silicate-hydrate gel which fills the interconnected pores and alters their distribution. This in turn reduces the porosity of the concrete matrix and increases its permeability resistance. Additionally, it behaves as a nucleus that tightly bonds with cement hydrate, forming a stable gel structure which shows closer packing. With the current research findings indicating significant early strength gain in conventional concrete, there are strong grounds to believe that NS could successfully be used and incorporated in recycled aggregate concrete to compensate the loss in mechanical strength and to improve the durability properties. The reference of this study has been taken from Curtin University.