Mehrnaz Etemadi - School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran Centre for Infrastructure Engineering, Western Sydney University, NSW, Australia.
Marjan Pouraghajan - School of Civil Engineering and Built Environment, Queensland University of Technology, Brisbane, Australia.
Hoorman Gharavi - School of Civil Engineering, Iran University of Science and Technology, Tehran, Iran.

In this research, the effect of adding different percentages of nano-silica and rubber powder on the compressive strength of the geopolymeric concrete specimens is investigated. The set of performed tests includes the compressive and tensile strength tests of the geopolymeric concretes. Due to the high rate of consumed concrete and the daily increase of the need for cement production, it is essential to consider environmental defects of this material and present new replacement products to move towards sustainable development. Low shrinkage, high compressive, and tensile strengths are among the main properties of produced concrete. Also application of nanoparticles, due to their specific physical and chemical properties, in many respects are very good candidates for producing novel materials with unique capabilities. Hence, the use of nano-silica as one of the nano technology products which could play the role of a very active artificial pozzolan in concrete has been under the focus of attention. Replacement of the rubber powder in the construction industry, due to the irresolvability of this type of wastes and also its specific structure such as improved ductility, reduced density, and improved resistance against concrete cracking has been practiced today. The aim of this research is to implement the two mentioned materials as additives in the concrete mix design and investigating their effect on the increase of the compressive and tensile strengths in concrete. The results of this research have shown that the use of nano-silica powder and rubber powder results in an increase of the compressive strength of concrete up to  1.45 times that of the control specimen using the nano-silica powder and 1.35 times that of the control specimen using the rubber powder.

nano silica, Geopolymer, Rubber powder