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The IUP Journal of Structural Engineering :
The Impact Strength of Concrete with Nanomaterials at Elevated Temperatures
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An experimental investigation was carried out to determine the influence of concrete with nanoparticles such as nanocement, nanofly ash, nanometakaolin and nanosilica fumes under elevated temperatures. M30, M40 and M50 grades of concrete were cast. For each grade of concrete, 10%, 20% and 30% of cement were replaced with nanomaterials. The particle size of nanomaterials was determined using a Scanning Electron Microscope (SEM). The impact strength of concrete with nanomaterials under various elevated temperature (250 °C, 500 °C, 750 °C and 1000 °C) was found using impact testing apparatus. The impact strength was found to be least for concrete specimens with replacement of nanometakaolin. It was also found that the impact strength of M30 grade concrete specimens was low as compared to other grades of concrete (M40 and M50).

 
 

Nanotechnology is an interesting but emerging field of study, which is under constant evolution, offering very wide scope of research activity. Normally, if the particle size ranges between 1 nm and 100 nm (Bjorn et al., 2012), they are generally called nanoparticles or materials. The fineness can reach up to molecular level (1 nm – 100 nm) by special processing techniques. As the fineness increases, the surface area increases, which increases the ‘reactivity’ of the material. Nanocement was produced in a high energy ball grinding mill and was used as a partial replacement to cement. Application of nanocement in concrete can lead to significant improvements in the strength and life of concrete. The mechanical behavior of concrete materials depends on structural elements and phenomena to a great extent which are effective on a micro- and nanoscale (Omer, 2007). The ability to target material modification at the nano structural level promises to deliver the optimization of material behavior and performance needed to improve significantly the mechanical performance, volume (Mohamed et al., 2013). Nanocomposites are produced by adding nanoparticles to a material in order to improve the properties of material (Nima et al., 2013). Concrete is a material most widely used in construction industry and made up of cement, sand, aggregate, water and mineral or chemical admixtures. The materials such as nanosilica, nanofly ash, and nanometakaolin are being combined with cement (Narendra Reddy and Ramesh, 2015). There are also a limited number of investigations dealing with the manufacture of nanocement. The use of finer particles (higher surface area) has advantages in terms of filling the cement matrix, densifying the structure, resulting in higher strength and faster chemical reactions, i.e., hydration reactions (Byung et al., 2014). Nanocement particles can accelerate cement hydration due to their high activity. Similarly, the incorporation of nanoparticles can fill pores more effectively to enhance the overall strength and durability.

 
 

Nanocement, Nanosilica fumes, Nanofly ash, Nanometakaolin, Elevated temperature, Impact energy