What is Ferroglobe Silica Fume?
Silica Fume, also known as microsilica, is an inorganic, amorphous silicon dioxide (SiO2), which consists of very small particles collected by the filter systems on our electric arc furnaces during the production of silicon and ferrosilicon.
The optimum quality of Ferroglobe Silica Fume is maintained by strict adherence to the testing regimes and characteristic values set out in the European Standard EN 13263, parts 1 and 2 or, where required, those specified in the American Standard ASTM C1240.
How does it work?
Due to its very small particle size (over 100 times finer than cement) and high SiO2 content, Silica Fume is a highly reactive pozzolan. This means it will react with the calcium hydroxide [Ca(OH)2] produced when cement hydrates. The small particle size means that the silica fume fills the spaces between the cement grains, improving the rheology of the mix and reducing the voids in the concrete. The ‘pozzolanic reaction’ with the Ca(OH)2 increases the amount of calcium silicate hydrates (CSH) produced, which intensifies the bond to the aggregates and improves the homogeneity of the mix, reducing porosity and permeability and increasing the strength.
“High Performance Concrete” is usually designed to incorporate silica fume, and sometimes other pozzolans, to achieve targeted characteristics for the structure being built. These can be flow or pumping performance, or enhanced durability, such as increased toughness, increased resistance to abrasion, to corrosion and chemicals, and life-cycle cost efficiencies. Highway bridges, parking decks, marine structures and bridge deck overlays are subject to constant deterioration caused by reinforcing steel corrosion, abrasion and chemical attack. Silica Fume will protect concrete against de-icing salts, seawater and abrasion from road traffic. Reinforcing steel corrosion and concrete deterioration are virtually eliminated, minimizing maintenance costs.
Where is it used?
The most important application is in the production of high-performance concrete and repair products (mortars and grouts), as the controlled addition of Silica Fume results in increased strengths and long-term durability.
High-performance Silica Fume concrete provides architects and engineers with greater design flexibility for structures such as bridges, viaducts, ports, skyscrapers, offshore platforms, as well as providing durability confidence for projects such as dams, power stations and industrial applications.
Other areas of use for silica fume include fibre-cement products, concrete roofing tiles, oil and gas well cements, gypsum and cement wallboards and refractories products.