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Nano technology is an emerging field of interest for civil engineering application. Among the nano materials presently used in concrete, nano-silica possess more pozzolanic nature. It has the capability to react with the free lime during the cement hydration and forms additional C-S-H gel giving strength, impermeability and durability to concrete. Present paper investigates the effects of addition of nano silica in normal strength concrete. Three types of nano-silica in the form of nano suspension having different amount of silica content have been investigated. Mix design has been carried out by using particle packing method. X-Ray diffraction (XRD) analysis has been carried out to find the chemical composition of control concrete and nano modified concrete. Further, experimental investigations have been carried out to characterize the mechanical behaviour in compression, tension and flexure. It has been observed that the addition of nano-silica in normal strength concrete increased the compressive strength and decreased the spilt tensile strength and flexural strength. Also, Rapid chloride permeability test (RCPT) has been conducted to know the chloride permeability of control concrete, nano modified concrete, and nano coated concrete. It has been observed that the chloride permeability is less for nano coated concrete.

A new variance ratio is proposed in this article that utilises the extreme values of asset prices. On the basis of the specification test, it is documented that there is excess volatility in the Indian stock market, whereas this feature is completely absent in the US. It is also found that such excess volatility is persistent in India in the sense that it gives rise to excessive path dependence. Furthermore, it is shown how such path dependence can be modelled from a theoretical point of view by way of the Binomial Markov Random Walk model. JEL Classification: G12, G14, G15

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