the importance of adding microsilica concrete-pg电玩城

microsilica is also called silica fume or agglomerated silica fume. it is called microsilica or silica fume in english. when ferro-alloys smelt ferro-silicon and industrial silicon (silicon metal), a large number of highly volatile sio2 and si gases are produced in the mineral thermal electric furnace. after gas discharge, they are formed by rapid oxidation, condensation and precipitation with air. it is a by-product of large-scale industrial smelting, and the whole process needs to be recycled with dusting environmental protection equipment, because the quality is relatively light, and also needs to be encrypted with encryption equipment.

as the fineness less than 1 is more than 80%, the average particle size is 0.1-0.3 moisture m, and the specific surface area is 20 ~ 28m2/g. its fineness and specific surface area are about 80 ~ 100 times of cement and 50 ~ 70 times of fly ash.

although pure cement can be used to make an hpc with compressive strength of up to 100 mpa, it will be much easier when microsilica is used. for concrete with strength over 100 mpa, the use of microsilica is almost indispensable. microsilica is used in both concrete filler and volcanic ash. when microsilica is used, the pore size in hydrated slurry is greatly reduced, and the pore size distribution is improved. for example, the results showed (ceb2fip1988) that, in order to obtain 70 mpa of concrete strength, the water-binder ratio required to apply pure cement was 0.35, while when adding 8%  microsilicar, the water-binder ratio could be 0.50. because the particles are so fine, they can react with ash in the early hours. according to carette and malhotra 1992, the contribution of  microsilica to concrete strength was mainly before 28d. therefore, in terms of long-term strength growth, it is generally believed that  microsilica concrete is inferior to pure cement concrete or fly ash concrete. the test results of  microsilica on the strength development of nsc cited by almad (1994) show that the increase of  microsilica content reduces the development of relative strength in the early stage. sandvik 1992 also found this phenomenon in the concrete of 65 mpa.

however, there have been reports of compressive strength shrinkage (de larrard and aiticin 1993) in some air samples with very low water-binder ratio. this reduction in strength usually occurs after the 90-day phase and is thought to be caused by internal self-drying and drying cracks. however, many other researchers' laboratory and field studies have shown no decrease in late strength of hpc. for example, the results of all drill core samples taken from six different hpc ages from 3 months to 3 years indicated that their strength was increasing. of course, the long-term strength growth potential of hpc is smaller than that of nsc.

therefore, the incorporation of  microsilica into concrete enhances the bond strength of cement net slurry and aggregate in hpc, eliminates the "weak connection" problem of different composite components in concrete, and makes hpc possess the properties of composite materials. bone granules play an enhanced role in hpc, not just inert fillers. the effect of  microsilica on the strength improvement of cement net slurry (no aggregate) is not great, but it can make the strength of concrete with the same water-binder ratio significantly higher than that of its matrix (net slurry).