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Sílica Active
FERBASA ACTIVE SÍLICA – QUALITY, SAVINGS, AND HIGH PERFORMANCE FOR YOUR CONSTRUCTION PROJECTS
How fumed sílica influences concrete, mortar, and paste composites.
Active silica is a highly reactive pozzolan, consisting essentially of silica in amorphous state, with spherical particles in diameters that are smaller than 10 m.
As an environmentally responsible action, fumed silica is collected in the bag filters of electric furnaces from gases generated during the production of metallic silicon or ferrosilicon alloys.
The product is homogeneous from a chemical (>85% SiO2) and physical standpoint (particles < 1 μm) and is adequate to be used with Portland cement in concrete, mortar, and paste composites. The elevated surface area improves the rheological aspects of the fresh state by optimizing the distribution of the paste’s particle size, thus contributing with water retention, increasing cohesion, reducing exudation and segregation, and facilitating the final finishing process.
Fumed silica, when reacting with Ca(OH)2 from the hydration of Portland cement, forms an additional hydrated calcium silicate (C-S-H) and confers special properties to concrete, mortar, and paste composites in terms of durability and mechanical performance compared to the standard properties of these composites without its presence, such as:
- a) increases compression and flexural strength;
- b) reduces porosity and permeability;
- c) increases sulfate resistance;
- d) creates resistance for chloride ion diffusion;
- e) mitigates alkali-aggregate reaction;
- f) reduces efflorescence occurrence;
- g) increases electrical resistivity;
- h) concrete with lower energy consumption and CO2 emissions.
The properties that active silica confers to the fresh and hardened states of concrete, mortar, and paste composites, compared to their properties without active silica, depend on the proportion of materials (trace) added to the Portland cement mass, as well as additives, preparation process, pouring, density, and curing conditions, among others.
