subject: The Application Of Micro-silica Fume In Concrete Construction [print this page] Micro-silica fume, also called silicon ash or condensed silica fume, someone also called it silicon power, is a by-product of ferrosilicon or silicon metal produce process, by submerged arc furnace in high purity quartz, coke and wood chips produced by the reduction, the main ingredient is SiO2, generally the silica fume color is between light gray and dark gray, SiO2 itself is colorless and their colors are mainly depending on the carbon and iron oxide content, the higher the carbon content, the color is darker, in addition, the encrypted silicon power is darker than the natural silica fume. Micro-silica fume concrete can be traced back to the 1940's, in Norway. The end of the seventies, Northern Europe and North America for the study of micro-silica fume concrete also made considerable progress, the early eighties, China made a lot of research work on micro-silica fume concrete in hydraulic engineering than multi-application, and achieved good results. In addition, micro-silica fume in concrete application by a powerful catalyst for technological progress and socio-economic factors, the durability of concrete is receiving attention increasingly.
The ordinary concrete works in a harsh environment may be severely damaged in a short period of time, thus threatening the quality of the project, greatly reduce the life of the project. But use cement, silica fume and fly ash and water reducer formulated high-performance concrete meet all the requirements, successfully used in various projects, significantly improve the performance of concrete, the concrete construction of flexible, fast and economical advantages to a new level. Micro-silica fume concrete with pozzolanic reaction, micro silica fume hydration formation rich silicon gel strength higher than the Ca (OH) 2 crystals, to work together with the cement hydration gel CSH. The filler particles used in the concrete voids, increase the bulk density and lower porosity.
The silica fume mainly supply in two forms, namely the original state microsilica and density silica fume. Original state micro-silica fume is directly through the precipitator to collect the resulting products, general bagged transport, the density is very small, less efficient in long-distance transport, the use of the micro-silica fume is directly broken bags and poured concrete mixer dust working environment, low working efficiency. density micro-silica fume is in order to solve the original state micro silica fume not suitable for long-distance transport, and the problem of low efficiency, the development of improved micro-silica fume loose density of micro-silicon densification. This technology make the original state micro-silica fume under the stream of compressed air, scroll gathered into a small group of particles, which greatly facilitates the use of weak, density micro-silica fume particles small granule group cohesion, the concrete mixer in mixing process is very easy to disperse, therefore the micro-silica fume particles can put into the mixer after the aggregate feeding, in order to ensure densified silicon micro particle group spread and good dispersion.
The SiO2 content is high, the performance of micro-silica fume will high, and other non-SiO2 impurity content is low. The metal powder supplier had been calculated: 15% of micro-silica fume cement replacement in concrete cement particles and the proportion of the number of micro-silica fume particles is 1:2000000, so it can see that micro silica fume is a superfine powder substance , why it can improve the strength of concrete, the key is to improve the strength of the bond between the cement paste and aggregates, can reduce the fresh water, and to prevent the moisture in the aggregate surface aggregation, thereby increasing the compactness of the interface of the transition zone and decrease the thickness of the interfacial transition zone. Micro-silica fume particle size is 100 times smaller than the cement particles, filling in the gap between cement particles, as if filled with cement granule aggregate between, to increase the density of concrete. However, the micro-silica fume is one of the prerequisites for these effects, that is, a good dispersion in concrete.
