Influence of Cement Content on Mechanical Properties of Concrete Containing Nano-silica

An experimental investigation was carried out to improve the mechanical properties of transportation concrete containing nano SiO2 by varying cement content. Compressive and tensile strength of three different cement content, 350, 400 and 450 kg/cm3, was tested in the reference and nano contained concretes. SEM photos were also used for micro structural studies. The results have shown that change of cement content causes change in strength of specimens in a convex manner with a maximum point. The addition of nano silica resulted in shifting this curve to higher cement content while the shape of curve was saved. Therefore with nano silica particles; the concrete can achieve higher strength in superior cement content. SEM observations have confirmed that nano silica can improve microstructure of concrete by decreasing the size and amount of crystals and reducing pores distribution. As observed in SEM studies, more uniform texture that produced by nano particles may put a stop to micro crack development and facilitate higher compressive and tensile strength, despite of increasing cement content.