Thursday 25 September 2014

NANAO-SILICA SOLUTIONS

ABSTRACT

Concrete is the most common used material for construction and its design consumes almost the total cement production in the world. The use of large quantities of cement produces increasing CO2 emissions, and as a consequence of this is the green house effect. A method to reduce the cement content in concrete mixes is the use of silica fines. One of the silica fines with high potential as cement replacement and as concrete additive is nano-silica (nS). However, the commercial nS is synthesized in a rather complex way, resulting in high purity and complex processes that make them non-feasible for the construction industry. In recent years a new nano-silica is produced from olivine. This nS, as well as commercially available nS, will be applied and tested.
This paper aims to present the state of the art of nS application in concrete, and in various fields focusing on its properties to render it suitable to be applicable. It includes importance of nS, the nS production process, their addition effect and their application especially in concrete.

INTRODUCTION:

      A long time used material in concrete is for the first time fully replaced by a nano material. It is well known in physics and chemistry that a well designed and developed nano material produces better and cheaper cost results than traditional materials,  the stabilization and reinforcement of matter properties at this level: a thousand fold smaller than the older level: “micro” (0.000001 mt).
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  Structured Settlement Investments
 
In the middle of 2003, a product which could replace micro silica seen the contaminant effects, having the better characteristics and at a reasonable cost was on the design table. The goal: silica fulfilling the environ-mental regulation: ISO-14001.
Atlast the challenge was fulfilled. Lab tests and production tests proved that the nano silica did not contaminate (because  of 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.
Nano silica giving 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.Mesothelioma Patients .

NEED FOR THE EMERGENCE OF NANO SILICA:
            Silica (SiO2) 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-silicate hydrate) reaction of concrete caused by calcium leaching in water as well as block water penetration and therefore lead to improvements in durability.

CO2 emissions from the global cement industry are significant and they are increasing. Global cement production is currently around 1.6bn tonnes/yr, and through the calcinations of limestone to produce calcium oxide and carbon dioxide, approximately 0.97 tonnes of CO2 is produced for each tonne of clinker produced. Around 900kg of clinker is used in each 1000kg of cement produced so the global cement industry produces around 1. tonnes of CO2 each year. This represents about 6% of the total worldwide man-made CO2 production. This is another important consideration for the development of nano silica. Endowment Selling .









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