Concrete is a material which is mostly used next to water in the construction industry because of its ability to be cast into any shape and size. The rapid growth of technology in the construction field has developed new innovative modern concrete consisting of the alternative materials other than the constituents of the conventional concrete. Among these developments, nano concrete exhibits high performance and strength attained by the application of nano materials. These nano materials have nano sized particles having larger specific surface area which in turn helps in accelerating the pozzolanic reaction in concrete and making the concrete denser. There is also need for development of new concrete along with fire resistance characteristics by using nano material. Hence, it is aimed at the usage of colloidal silica of two types in concrete and to study strength characteristics of concrete of M20 grade when subjected to heat exposure at higher temperatures. The strength residue are measured in terms of modulus of rupture, compression and split tensile of M20 grade of concrete which are evaluated at different temperatures of 100, 200, 300, 400 and 500oC for time of 1, 2, 3 and 4 hours exposure durations to predict influence of colloidal silica on concrete mixes. The results are compared with conventional concrete and the utilization of colloidal silica has improved the residual strength parameters. Colloidal silica due to its pozzolanic nature, it has filled the voids in conventional concrete and developed a new innovative dense concrete with enhanced strength properties at elevated temperatures.
