RE: NANO CONCRETE
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Nanoconcrete is one of the most active research areas that encompass a number of disciplines including civil engineering and construction materials, Currently, the most active research areas dealing with cement and concrete are: understanding of the hydration of cement particles and the use of nano-size ingredients such as titanium oxide, silica, carbon nanojubes, and nano- sensors. if cement with nano-size particles can be manufactured and processed, it will open up a large number of opportunities in the field of ceramics, high strength composites etc. it will elevate the status of Portland cement to a high tech material in addition to its current status of most widely used construction material. The main objective of this paper is to outline some of the applications of nanotechnology in concrete and comparing this concrete with the ordinary concrete
"Nano technology is the study of the control of matter on an atomic and molecular scale. It deals with the size 100 nanometers or smaller, and involves developing materials or devices within that size".
A long time used material m concrete is for the first time fully replaced by a nano maternal. lt is well known m physics and chemistry that a well designed and developed nano material produces better and cheaper cost results than traditional materials.
Micro silica has been one of the world's most widely used products for concrete for over eighty years. Its properties allowed high compressive strength concretes; water and chemical resistant concretes, and they have been part of many concrete buildings that we see nowadays. Its disadvantage, though, has been its relatively high cost and contamination, which affects the environment and the operators' health. As micro silica, as a powder, is thousand fold thinner than cigarette smoke. Operators must take special precautions to avoid inhaling micro silica and not to acquire silicosis, an irreversible d.sease.hcnce to over come all tese above ill-effects of micro silica, nanotechnology was introduced in the world of concrete.
Nanotechnology and Concrete
Concrete is probably unique in construction in that it is the only material exclusive to the business and therefore is the beneficiary of a fa.r proportion of the research and development money from industry. The following section describes some of the most promising applications of nanotechnology in construction that are being developed or are even available today.
Some of the applications of nanotechnology are:
• Cuore concrete- nano silica
• Titanium dioxide
• Carbon nanotubes
CUORE CONCRETE NANO-SILICA
Fig – Showing the mixing of nano silica in concrete
physics, chemistry and recent nanotechnology advances, the challenge was fulfilled.Lab tests and production tests proved that the nano silica did not contaminate (because its state), but it also produced better results than micro silica, and a litre bottle of the product was equivalent to a barrel full of micro silica, extra cement and super plasticizing additives.Silica (SiCte) is present in conventional concrete as part of the normal mix. However, one of the advancements made by the study of concrete at the nanoscale is that particle packing in concrete can be improved by using nano-silica which leads to a densifying of the micro and nanostructure resulting in improved mechanical properties. Nano-silica addition to cement based materials can also control the degradation of the fundamental C-S-H (calcium-silicatehydrate) reaction of concrete caused by calcium leaching in water as well as block water penetration and therefore lead to improvements in durability. Related to improved particle packing, high energy milling of ordinary Portland cement (OPC) clinker and standard sand, produces a greater particle size diminution with respect to conventional OPC and, as a result, the compressive strength of the refined material is also 3 to 6 times higher (at different ages). Fly ash not only improves concrete durability, strength and, importantly for sustainability, reduces the requirement for cement, however, the curing process of concrete is slowed by the addition of fly ash and early stage strength is also low in comparison to normal concrete. With the addition of SiCh nanoparticles part of the cement is replaced but the density and strength of the fly-ash concrete improves particularly in the early stages. Research into hematite (Fe20;,) nanoparticles added to concrete has shown that they also increase strength as well as offering the benefit of monitoring stress levels through the measurement of section electrical resistance.
Because of its innovation the nano silica was tested for over a year in the world's largest subterranean copper mine to prove its long term characteristics. Cuore concrete takes care of the environment, the concrete and the operators' health. It is the first nano product that replaced the micro sihca.Cuore concrete surpassed the expectations of its design and gave concrete not only the high initial and final resistance but in addition, plasticity, impermeability, minor final cost of work, and cement savings of up to 40%. Also, it lowered the levels of environmental contamination
In high compressive strengths concretes (H-70), Cuore concrete is 88% more efficient than micro silica, added to concrete and super plasticizers. ( For an average 9,43 Kg. of Cuore concrete Nanosilica, 73Kg. of all the others additives are used).
The production cost of is drastically lower than using the traditional production method or formulas.
The cone test shows that It preserves the cone shape for more than one hour, (with a relation of H2O/Cement=0.5, adding 0.5% of Nano silica of the metric volume of the cement used, it conserved a its circle shape of 60 cm lor two hours, with a lost of only 5%). The nano silica has a plasticity that has been compared to the pohcarboxilate technology. Therefore the use of super plasticizing additives is unnecessary.
• High workability with reduced water/concrete levels, for example: 0,2.
• Easy homogenization. The reduction of mixing times allows concrete plants to increase their production
• Depending on the cement and the formulations used for concrete (tests from value H-30 to H-70), shows that the material provides compressive strengths between 15 MPa and 75 MPa at 1 day; 40 MPa and 90 MPa at 28 days and 48 MPa and 120 MPa at 120 days.
• Nano silica fully complies with ISO 14001 regulations regarding the environment and health. It preserves operators of the danger of being contaminated with silicosis and does not contaminate the environment.
It successfully passed all the tests and since the beginning of this year it is being commercialized in different parts of the world.