Nano Technology in Civil Engineering

By V Kartik Ganesh Department of Civil Engineering, SRM University Kattankulathur, Chennai-603203, INDIA Abstract The innovation of relevant nanotechnology and its significance in civil engineering practice is illustrated in this paper for broadening vision. Nanotechnology deals with understanding, controlling and manipulating matter at the level of individual atoms and molecules in the range of 0. 1–100 nm (10-9 m). It creates materials, devices, and systems with new properties and functions.

The role of nanotechnology in the conceiving of innovative infrastructure systems has the potential to revolutionize the civil engineering practice and widen the vision of civil engineering. Following this the analysis were carried out in ductile structural composites along with its enhanced properties, low maintenance coatings, better properties of cementitious materials, reducing the thermal transfer rate of fire retardant and insulation, various nanosensors, smart materials, intelligent structure technology etc.

The properties like self-sensing, selfrehabilitation, self-cleaning, self-vibration damping, self-structural health monitoring and self-healing are the key features. To execute these, the gap between the nanotechnology and construction materials research needs to be bridged. This paper first presents the background information and current developments in nanotechnology and civil engineering in general followed by the merits and demerits of their interdisciplinary approach.

Further the details of application oriented nanotechnology-enabled materials and products that are either on the market or ready to be adopted in the construction industry and also their possible consequences over the time is elucidated. Some of the major instances of current applications of nanotechnology in the field of civil engineering across its different sections around the globe are exemplified. The most challenging economic factors concerned with its practicality are discussed briefly.

Finally the future trend, potential and implications of nanotechnology development in civil engineering towards more economical infrastructure, low cost maintenance with longer durability are deliberated. Keywords—Civil Engineering, Nanomaterials, Nanotechnology, Sustainability. I. INTRODUCTION A. BACKGROUND As people involved in construction, we are very familiar with the concept of getting raw materials, bringing them together in an organized way and then putting them together into a recognizable form.

The finished product is a passive machine. It works and slowly decays as it is used and abused by the environment and the owners of the project. Construction then is definitely not a new science or technology and yet it has undergone great changes over its history. In the same vein, nanotechnology is not a new science and it is not a new technology either. It is rather an extension of the sciences and technologies that have already been in development for many years. The size of the particles is the critical factor.

At the nanoscale (anything from one hundred or more down to a few nanometres, or 10-9 m) material properties are altered from that of larger scales. Another important aspect is that, as particles become nano-sized, the proportion of atoms on the surface increases relative to those inside and this leads to novel properties. It is these “nano-effects”, however, that ultimately determine all the properties that we are familiar with at our “macro-scale” and this is where the power of nanotechnology comes in – if we can manipulate elements at the nanoscale we can affect the macrowww.

engineeringciv il. com/nanotechnology -in-civ il-engineering. html#more-4643 1/10 1/10/13 Nanotechnology in Civ il Engineering properties and produce significantly new materials and processes. B. WHAT IS NANOTECHNOLOGY ? Nano, which comes from the Greek word for dwarf, indicates a billionth. One nanometre is a billionth of a metre. Definitions of ‘nanotechnology’ vary, but it generally refers to understanding and manipulation of matter on the nanoscale, say, from 0. 1 run to 100 nm.

The significance and importance of controlling matter at the nanoscale is that at this scale different laws of physics come into play (quantum physics); There are two ways to approach the nanoscale: shrinking from the top down, or growing from the bottom up. The ‘top down’ approach entails reducing the size of the smallest structures towards the nanoscale by machining and etching techniques, whereas the ‘bottom up’ approach, often referred to as molecular nanotechnology, implies controlled or directed self-assembly of atoms and molecules to create structures [4].

C. NANOTECHNOLOGY IN CONSTRUCTION The construction industry was the only industry to identify nanotechnology as a promising emerging technology in the UK Delphi survey in the early 1990s [18]. The importance of nanotechnology was also highlighted in foresight reports of Swedish and UK construction [19-20]. Furthermore, ready mix concrete and concrete products were identified as among the top 40 industrial sectors likely to be influenced by nanotechnology in 10-15 years [17].

However, construction has lagged behind other industrial sectors where nanotechnology R&D has attracted significant interest and investment from large industrial corporations and venture capitalists. Recognising the huge potential and importance of nanotechnology to the construction industry, the European Commission in late 2002 approved funding for the Growth Project GMA1-2002-72160 “NANOCONEX” – Towards the setting up of a Network of Excellence in Nanotechnology in Construction. II.

APPLICATIONS OF NANOTECHNOLOGY IN CIVIL ENGINEERING Nanotechnology can be used for design and construction processes in many areas since nanotechnology generated products have many unique characteristics. These characteristics can, again, significantly fix current construction problems, and may change the requirement and organization of construction process. Some of its applications are examined in detail below: A. CONCRETE Concrete is one of the most common and widely used construction materials. Nanotechnology is widely used in studying its properties like hydration reaction, alkali silicate reaction (ASR) and fly ash reactivity [2].

Alkali silicate reaction is caused due to alkali content of cement and silica present in reactive aggregates like chert. The use of pozzolona in the concrete mix as a partial cement replacement can reduce the likelihood of ASR occurring as they reduce the alkalinity of a pore fluid. Fly ash not only improves concrete durability, strength and, importantly for sustainability, reduces the requirement for cement, however, the curing process of such concrete is slowed down due to the addition of fly ash and early stage strength is also low in comparison to normal concrete.

Addition of Nano-silica leads to the densifying of the micro and nanostructure resulting in improved mechanical properties. With the addition of nano-SiO2 part of the cement is replaced but the density and strength of the fly-ash concrete improves particularly in the early stages. For concrete containing large volume fly ash, at early age it can improve pore size distribution by filling the pores between large fly ash and cement particles at Nano scale. The dispersion/slurry of amorphous nano-SiO2 is used to improve segregation resistance for self-compacting concrete [26].

The addition of small amount of carbon nanotube (1%) by weight could increase both compressive and flexural strength [1]. This can also improve the mechanical properties of samples consisting of the main portland cement phase and water. Oxidized multiwalled nanotubes (MWNT’s) show the best improvements both in compressive strength (+ 25 N/mm2) and flexural strength (+8 N/mm2) compared to the reference samples without the reinforcement. www. engineeringciv il. com/nanotechnology -in-civ il-engineering. html#more-4643 2/10