Introduction
Unlike the situation where conventional technologies are used to manipulate construction materials at the millimeter scale to achieve certain properties, similar properties can be achieved at the nanoscale by using nanotechnology (Srivastava & Singh, 2011). Nanotechnology has proved to be very useful in biological, physical, and chemical disciplines to solve real-world problems at the levels of the atomic and sub-micron scale.
Here, the usefulness is due to the ability to precisely manipulate matter at the supramolecular level (involving manipulation of discrete subatomic particles and the coupling effects of charged particles). Typically, nanotechnology is an area that has promised new solutions to many civil engineering problems that were encountered using conventional technologies.
Srivastava and Singh (2011) maintain that the behavior of engineering materials at the nanoscale presents opportunities for engineers to build structures they can control at the atomic level. Some of the engineering materials include nano-composites and nanotubes that are used for nano-lithographic fabrications.
Nanoscale
Srivastava and Singh (2011) note that nanotechnology describes how exploring the head of a pin becomes a journey that includes explorers from different disciplines such as numerical physics, electrical engineering, materials science, and atomic physics, among others. In a nutshell, nanotechnology is no longer science fiction but a reality that is used to manipulate matter at the nanoscale.
Nanotechnology is defined as the “ability to observe, measure, manipulate, and manufacture things at the nanometer scale, the size of atoms and molecules” (Giri, Goswami & Perumal, 2013, p.23). The term is also defined as “the science, engineering, and technology related to the understanding and control of matter at the length scale of about 1 to 100 nanometers” (Giri et al., 2013, p.23).
In contrast to the use of conventional technologies to manipulate matter at the millimeter scale to achieve the desired properties, nanotechnology enables technologists to control the properties of matter at the nanometer scale.
To understand the extent to which the nanoscale works, it is important to compare the conventional measurement scale with the nanometer. Here, the nanometer (nm) is 10-9 of a meter, whereas the width of the hair is 100 000 nanometers. According to Giri et al. (2013), nanoscale has increased the promise that particles can be manipulated to form the desired structures.
Observations show that as we approach the nanoscale, the behavior of a particle changes tremendously, revealing two types of characteristics. According to Giri et al. (2013), the first characteristic is described as a discontinuous change of the properties exhibited by the material when it is reduced into an infinitesimally small particle.
The second characteristic is referred to as the ‘continuous property’ where the particles are interconnected to form a continuous chain of nanoparticles. In both cases, the characteristics are generally referred to as qualitative. However, it is generally agreed that the behavior of the same particles at the millimeter scale changes drastically when the nanoscale is reached (Giri et al., 2013).
Nanoscale properties
To understand the nanoscale and the emergency of its properties, it is important to understand the atom and the molecule in the context of the nano measurement. The nanoscale measures the size of the nanoparticles at the atomic and molecular levels. Srivastava and Singh (2011) maintain that the basic levels at which materials exist are the atom, which has led pioneers to suggest that an atom-by-atom construction of materials is a miniaturized approach for constructing large objects.
However, at the atomic level, the definition of the nanoscale does not satisfy the unique properties that emerge when compared with those at the nanoscale of the same material. Typically, a simplified view of objects assembled by the use of atoms does not guarantee that the objects will have the same properties as those build by assembling nanoparticles.
On the other hand, a molecule (composed of two or more atoms) is the smallest particle that retains the properties of a material without changing its chemical identity. Here, the atom and the molecule only provide measurements at the upper limit of the nano realm, without divulging further into the nuclei. On the other hand, the upper limit of the quantum size of the nanoscale is represented by the lower limit of the nano realm of a molecule.
The mesoscale is used to measure the lower limit, which is demarcating points at which quantum mechanics ceases to work, and further measurements in the nano-realm are taken by the use of the atom. A very important property for engineers arises at the nano-realm because atoms can be programmed to build nano-blocks that have atomic-level precision. The resulting nano-block maintains the properties that cannot be modified when its physical and chemical attributes are measured.
The distinguishing nature of the nano object is that it has attributes such as individuality, quality, and specificity that correspond to a quantum limit of smallness that cannot be reduced any further. However, depending on the environment where the nano object is applied, it can be reduced to become smaller than an atom (Srivastava & Singh, 2011). Typically, scientists use the nano property to build materials that have nano-metric properties, which make them suitable for use in specialized areas.
The nanomaterial
Nanomaterials form the bulk of new innovations and technologies that have fundamentally changed the quality of civil engineering materials and products. Nanomaterials usually have fundamental properties, such as the ability to measure the surface using the nanoscale. It means that the external or internal dimensions of the surface structures can be determined using the nanoscale.
The external surfaces of a nano object are used to determine the right category of nanomaterials to use to build the nano object. It is clear that the internal measurements of the nanomaterial taper from small to large when they are taken along the principal axis that is not straight (Srivastava & Singh, 2011).
Application in civil engineering
The winner of the coveted Nobel Prize laureate Richard Frenchman said that a lot of opportunities exist if we are able to develop the ability to manipulate and control things. Richard Frenchman directed his speech to what is today known as nanotechnology. In pursuit of that goal, scientists have endeavored to manipulate the structural arrangements of atoms to create nanomaterials that are widely applied in many engineering disciplines today.
According to Srivastava and Singh (2011), among the areas of fundamental importance where such materials find a wide application based on the nano-property is to make carbon nanotubes. It is possible to make carbon tubes based on the electrostatic forces that exist between the atoms and the resulting quantum effects of the nanomaterial.
Quantum effects and electrostatic forces play an important role because binding the atoms together to build a nano object as we approach the nanoscale without any effects being felt on the behavior of the nanoparticles due to the force of gravity. The nanoscale concept allows us to make smaller products using either the top-down or bottom-up approach. The top-down approach basically consists of using larger parts or machines to make smaller parts of a device.
A typical example includes the use of the Atomic Force Microscope (AFM) to decompose chemicals on the surface of an object to create certain patterns. On the other hand, the bottom-up approach is the process of discretely manipulating atom-by-atom by arranging them to create complex structures that have the desired properties. Examples include the hybrid fabrication of civil engineering construction materials to meet the standard specification with the right engineering nano-properties.
Construction industry
Giri et al. (2013) argue that nanomaterials are widely applied in the construction industry to make high quality engineering structures and products. An example is where a high-quality concrete is made by manipulating the behavior of cement particles when they undergo hydration.
Using nanotechnology, engineers can easily understand the best methods to use in mixing foreign particles such as silica and alumina to yield high-quality cement that has better mechanical properties, which makes it stronger, durable, and easy to use. In addition, technology has made it easy to make stronger steel and polymeric materials from carbon to make self-cleaning glass. Figure 1, part A illustrates an example of a single-walled nanocarbon material, and part B shows a double-walled nanotube made from carbon.
Carbon nano tubes
The dimensions on both diagrams A and B show the length and width of the particles and the distances that separate the layers of the multi-walled carbon and the single-walled carbon nano tubes.
Typical examples of the nanoparticles that have found widespread use in the civil engineering environment include carbon nanotubes (CNT’s) and titanium dioxide (TiO2). Each material has unique properties at the nanoscale, which can be exploited to make them exhibit new properties (Giri et al., 2013).
For instance, titanium dioxide (TiO2) can be used on the surface of a concrete block or on steel to break dirt, which is then easily washed away. On the other hand, the unique properties of carbon nanotubes make them suitable for use to make stronger cement that is suitable for use in the construction industry.
According to Giri et al. (2013), carbon nanotubes have cylindrical shapes with very small diameters that can be measured using the nanoscale and lengths that are measured on the millimeter scale. The thermal conductivity of the material, when measured along its axis, yields a young’s modulus, which is five times that of steel (Giri et al., 2013).
It is adding titanium oxide to paint and cement yields high-quality concrete structures and windows by oxidizing organic materials and oxygen that are present in the materials. In addition, titanium oxide has good anti-fouling properties, which makes it suitable for use in coating outdoor building materials, cutting the polluting effects of airborne pollutants that result from construction activities.
Exposing TiO2 to ultraviolet light makes it develop good hydrographic properties, which enables it to attract water molecules when used on self-cleaning windows and anti-fogging materials.
Concrete
Giri et al. (2013) maintain that cement has been used for many centuries to make concrete blocks in the construction industry because of its properties, such as the strength it gains when it sets, making it suitable to make concrete blocks that are used in the construction industry. On the other hand, the advent of nanotechnology has drastically improved the properties of cement, making it suitable for use in a wide variety of applications.
Srivastava and Singh (2011) assert that using techniques such as the Focused Ion Beam (FIB), Atomic Force Microscopy (AFM), and the Scanning Electron Microscopy (SEM), engineers are able to manipulate cement to acquire the unique properties that make it suitable for use in the construction industry at the nano level.
On the other hand, Giri et al. (2013) assert that nano-silica can be used to modify the fundamental properties of cement using any of the cement packing technologies. In addition, the rate at which cement-based materials such as calcium-silicate-hydrate degrade can be slowed down or stopped completely by the use of nano cement particles (Srivastava & Singh, 2011).
Degradation is caused by the leaching effects of calcium carbonate getting mixed with blocked water to form calcium hydrogen carbonate. Adding TiO2 into cement improves its properties drastically and makes it able to break some of the pollutants found in cement through catalytic actions, which is an important property for cutting outdoor pollution (Giri et al., 2013).
On the other hand, using nanotechnology has made it easy to develop Self Compacting Concrete (SCC), which makes construction work cheaper and easy because the resulting concrete does not require compaction or vibrations, but settles down naturally on its own.
Researchers in the construction industry have discovered that using SCC cuts down the labor costs in the construction industry by 50% because the concrete made from nano-cement is easy to work on and pours 80% faster than normal cement. On the other hand, engineers are able to make excellent non-composite materials, which could enable them to cut down the labor costs for repairing and maintaining new structures (Giri et al., 2013).
Nano-composites
According to Giri et al. (2013), nanocomposites are materials that are small in size and durable, with special properties that are achieved by mixing nanotubes with alumino-silicates. The nano-composites are made of micro-structures, which are modulated at the atomic level to form nano-sized clusters, the building blocks of engineering materials having a width of 1-100 nm. Some of the nano-composites include nano-clays that can occur either in one-nano-scale, three nano-scales or in two nano-scales.
However, by combining nano-composites with other materials, it is possible to make products with extra-ordinary properties. Some of the properties include the ability to penetrate and close up small gaps and cracks that appear on materials, including concrete surfaces, leading to better-reinforced concrete with stronger bonds.
Conclusion
In conclusion, despite the argument that nanotechnology is not new, engineers and scientists agree that it is a new technology that has revolutionized the way engineers work in the field of civil engineering to produce high-quality work. Typically, nanotechnology is the ability to manipulate the attributes of different materials such as cement, at the nanoscale to exhibit new and better properties.
References
Giri, P. K., Goswami, D. K., & Perumal, A. (2013). Advanced Nanomaterials and Nanotechnology: Proceedings of the 2nd International Conference on Advanced Nanomaterials and Nanotechnology, Guwahati, India: Springer Science & Business Media.
Srivastava, A., & Singh, K. (2011). Nanotechnology in civil engineering and construction: a review on state of the art and future prospects. Proceedings of Indian Geotechnical Conference, 1(024), 1077-1080