The objective of this study is to review the role of nanotechnology in civil engineering applications. It also discusses the application of instruments to reach material properties of nano-scale. Furthermore, it has been observed that better understanding and engineering of complex structures made by cement, steel or composite materials at nano-level will definitely result in a new generation of construction materials with higher performance in strength, durability, and other properties.

Nanotechnology is the re-engineering of materials and devices by controlling the matter at the atomic level . In other words, nanotechnology is a field that is dominated by developments in basic physics and chemistry research, where the phenomena on atomic and molecular levels are used to provide materials and structures that perform tasks that are not possible using the materials in their typical macroscopic form. The evolution of technology and instrumentation, as well as its related scientific areas, such as physics and chemistry, is making the research on nanotechnology aggressive and evolutional. Not surprisingly, it has been observed that expenditure on nanotechnology research is significant.

In nano-level, gravity becomes unimportant, electrostatic forces take over, and quantum effects come in. Furthermore, as particles become nano -sized, the proportion of atoms on the surface increases relative to those inside, and this leads to novel properties. Current researchers dealing with nano- science and nanotechnology are exploring these novel properties since at nano- scale, we can alter the macro-properties and produce significantly new materials and processes.

 Nanotechnology, therefore, allows the design of systems with high functional density, high sensitivity, special surface effects, large surface area, high strain resistance, and catalytic effects. All attributes are directly or indirectly the result of the small dimensions of nano-particles. 

Nano-cement:

Portland cement is the most widely used construction material. It can be argued that concrete utilizes nanotechnology because it contains nano- particles as its ingredients, including nano-water particles and nano-air voids. However, it is not the application of the technology at nano-level. If it is possible to create the technological tools and organize the amount and locations of these nano-ingredients in a scientific way, then, concrete can experience the advances of nanotechnology. Concrete is, after all, a macro-material, strongly influenced by its nano-properties and understanding it at nano level can provide the avenues for improvement of strength and durability. The particle size of cement can be reduced to nano-size or can be modified by adding nano-tubes and reactive nano-size silica particles. A number of investigations have been carried out to develop smart concrete using carbon fibers and it has been found that instead of carbon fibers, nano-carbon tubes added with nano-cement are more effective.