There are different types of micro silica fume according to different classification criteria. In terms of supply form, it can be broadly divided into two categories, one is the undensified silica fume also said to be the raw silica fume, and the other is the densified silica fume. So what is densified silica fume?
What is densified silica fume?
densified silica fume is a product of dried and fluffy silica fume in its original state (unencrypted) after densification. According to the difference of density, it is divided into fully densified silica fume and semi-encrypted silica fume. Dense silica fume in the concrete system, due to the addition of coarse aggregate, play a strong abrasive effect, after the high-power mixer to break up, less clusters can be relatively good dispersion, and the volcanic ash reaction of silica fume play a role in improving the interface transition zone, so that the compressive strength of concrete increased.
The density of semi-encrypted micro-silica powder is generally in the range of 250-350 kg/m3. Semi-encrypted micro-silica fume is mainly composed of glassy SiO2, the particles are characterized as ultra-fine powder, the majority of particle size is less than 1 um, the average particle size is 0.1 um, with a high specific surface area (300-400m2/kg) and volcanic ash activity.
The clustering effect of fully densified silica fume in the hardened slurry of net slurry is obvious, and some of the silica fume clusters have obvious cracks, which increase the total porosity of net slurry, causing the compressive strength of net slurry to decrease, and need to be fully mixed and broken up. Fully densified silica fume is more often used in concrete projects, with a density of about 550-700 kg per cubic meter, and is generally transported in ton bags, which greatly reduces transportation costs.
Application scope of Densified silica fume
Commercial concrete, high-strength concrete, self-leveling concrete, indefinite refractory materials, dry-mixed (ready-mixed) mortar, high-strength non-shrink grout, wear-resistant industrial flooring, repair mortar, polymer mortar, insulation mortar, impermeable concrete, concrete compacting agent, concrete anticorrosion agent, cement-based polymer waterproofing agent; rubber, plastic, unsaturated polyester, paints, coatings and other polymer materials for reinforcement, modification of ceramic products, etc.
