This Article Cover Concepts Of “Nano Concrete” Why Nano Concrete Technology Used And Various Benefits Of Nano Technology.
Let’s Start With,
Introduction To Nano Concrete
Particular relevance for concrete is the greatly increased surface area of particles at the Nano scale. As the surface area per mass of a material increases, a greater amount of the material can come into contact with surrounding materials, thus affecting reactivity.
If cement with Nano-size particles can manufactured and processed, it will open up a large number of opportunities in the fields of ceramics, high strength composites and electronic applications.
This will elevate the status of Portland cement to a high tech material in addition to its current status of the most widely used construction material. Very few inorganic cementing materials can match the capabilities of Portland cement in terms of cost and availability.
Currently, the most active research areas dealing with cement and concrete understanding of the hydration of cement particle sand the use of Nano-size ingredients such as alumina and silica particles.
Nanotechnology considers two main approaches
- The ‘‘top down” approach in which larger structures reduced in size to the Nanoscale while maintaining their original properties without atomic-level control (e.g., miniaturization in the domain of electronics) or deconstructed from larger structures into their smaller composite parts.
- The ‘‘bottom-up” approach, also called ‘‘molecular nanotechnology” or ‘‘molecular manufacturing” in which materials engineered from atoms or molecular components through a process of assembly or self-assembly
Thus the basic concept behind Nano modification of materials is that of bottom-up engineering, starting with engineered modifications to the molecular structure with an aim to affect the bulk properties of the material.
Conceptually, this is simply an imitation of nature. In practice, the introduction of nanotechnology represents a revolution that is allowing for the development of high-performance and long-lasting products and processes within an ideal context of sustainable development.
Nano-concrete defined as a concrete made with Portland cement particles that are less than 500 Nano-meters as the cementing agent. Currently cement particle sizes range from a few Nano-meters to a maximum of about100 micro meters. In the case of micro-cement the average particle size reduced to 5 micrometers. An order of magnitude reduction needed to produce Nano-cement.
Why Nano Technology For Concrete
WHY NANOTECHNOLOGY FOR CONCRETE?
- Development of high-performance cement and concrete materials as measured by their mechanical and durability properties;
- Development of sustainable concrete materials and structures through engineering for different adverse environments, reducing energy consumption during cement production, and enhancing safety;
- Then Development of intelligent concrete materials through the integration of nanotechnology-based self-sensing and self-powered materials and cyber infrastructure technologies;
- Development of novel concrete materials through nanotechnology-based innovative processing of cement and cement paste; and
- Development of fundamental multi scale model(s) for concrete through advanced characterization and modeling of concrete at the Nano-, micro- and macro scales.
- Improves the material’s bulk properties.
- Ability to control or manipulate materials at the atomic scale.
- To obtain thinner final products and faster setting time.
- Cost effectiveness.
- Lowered levels of environmental contamination.
Benefits Of Nano Concrete
- Concrete is stronger, lighter and more durable.
- Concrete with good workability.
- Lower cost per building site.
- Cessation of contamination caused by micro silica solid particles.
- Concrete with high initial and final compressive and tensile strengths.
- Cessation of super plasticizing utilization.
- Cessation of silicosis risk.
Concrete And Nanotechnology
One can claim that concrete utilizes nanotechnology because it contains Nano-particles as ingredients including Nano-water particles and Nano-air voids. However, to claim the use of nanotechnology, we should be able to control the amount and the locations of these Nano- ingredients inside the final products. The scales of various constituent materials of concrete shown in Fig.
If we can create chemical or mechanical tools to control Nano-scale pores and the placement of calcium-silicate hydration products then concrete becomes a product of nanotechnology.
Nano-Scale Silica Fume For Improving Concrete Performance
Ultra-fine amorphous colloidal silica was found to be much more efficient than micron sized silica for improving the performance such as permeability, and subsequently, durability. In addition, reduced amount of about 15 to 20 kg of Nano-silica was found to provide same strength as 60 kg of regular or micro silica.
Alkali-Silicate Reaction (ASR) Studies
ASR results in the formation of alkali/silica gel, which expands and causes significant material damage. The gel formed due to the reaction between cement alkalis and a reactive form of silica from aggregates or supplementary additions. FHWA researchers are using neutron scattering and positron annihilation spectroscopy to measure Nano-scale changes in gel microstructure as a function of gel chemistry, temperature and relative humidity.
Fly Ash Reactivity Characterization
FHWA is also funding a research study to examine interactions between fly ash and Portland cement gel Nano-structure. Small-angle neutron scattering used to quantify the changes on a Nano-scale as a function of time and fly ash composition.
Cement Hydration Kinetics
Conventional analytical methods are unable to provide an accurate model for the rate of cement’s reaction with water as a function of temperature, water/cement ratio, and grain size because the reactions occur in the Nano-scale pores of the cement gel.
Therefore, scientists from National Institute for Standards & Technology’s (NIST) Center for Cold Neutron Research and FHWA are using neutron scattering methods to measure motions and reactions of water at a Nano-scale. This study expected to explain the effects of various factors on the rate of development of cement’s fractal Nano-scale structure.
Carbon Nano Tubes
- Carbon nano tubes made with graphite, There are two types of carbon nano tubes.
- Single-walled carbon nanotubes
- Multi-walled carbon nanotubes
- Nano Silica:-
Nano silica is the modified form of conventional silica. The particle size of nano-silica is 20 nanometer.
Polycarboxylates is a polymer-based concrete admixture. It is HRVR (high range water reducing admixture) type concrete admixture.
Advantages of Nano Concrete
- Reduce cost.
- Higher-strength compares to conventional concrete.
- Good workability because the water-cement ratio is very low.
- Saving of cement up to 35%.
- Nanoparticles can fill even micro void.
- Nanoparticles enhance the hydration process.
- Disadvantages of Nano Concrete:
- Rare availability of nano materials used in nano concrete.
- Rare availability of equipment to produce nano concrete.
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