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The use of silicon powder

Preparation strengths exceeding 100 MPa concrete, the use of silicon powder is almost indispensable. silicon powder in the concrete from the filler material and ash materials. The use of silicon powder, which greatly reduces the pore size in the hydration of the paste to improve the pore size distribution, so the strength and the permeability decreases. For example, the results show that (CEB2FIP1988), 70 MPa concrete strength, the application of pure cement water glue than 0.35 when the plus 8% silicon powder, water-cement ratio of 0.50. Very fine silicon powder particles, they can occur within a few hours early pozzolanic reaction. Accroding the reports (Carette and Malhotra, 1992), the contribution of silicon powder on the strength of concrete before the 28d. Therefore, the long-term strength growth is generally believed that the silicon powder concrete than plain cement concrete or fly ash concrete. Almad (1994) reference to the silicon powder NSC strength development of the test results showed that the silicon powder content increased early relative lower strength development in 65 MPa concrete, Sandvik 1992 also found this phenomenon. However, although in the same water-cement ratio under the silicon powder concrete early development of the relative intensity of slower than plain cement concrete strength greatly improve by adding silicon powder, the absolute intensity of the silicon powder concrete than plain cement concrete high. On the other hand, experience from metal powder supplier shows that the HPC early strength development than the NSC fast, although the HPC setting time may be slightly delayed, after the condensation of hydration is greatly accelerated because of the superplasticizer and silicon powder. The result is usually the strength development after the condensation is very fast.For some air drying or the conservation of low water-binder ratio of silicon powder concrete specimens, the compressive strength retraction reported (De Larrard and Aiticin 1993). This strength reduction usually occurs after 90 d age, generally considered to be caused by internal self-dry and dry cracks. However, many other researchers, laboratory and field studies have shown that does not reduce the strength of HPC late. For example, obtained from six different HPC 3 months to the age of the drill core sample test results showed that their strength is growing. Of course, with the NSC of HPC long-term strength of less growth potential.The durability of concrete including the anti-freeze capability ,anti-permeability, chemical resistance, reinforced erosion resistance ability and anti-abrasion performance. Here talk about the influence on its nti-freeze capability, anti-permeability and chemical resistance.a) Frost resistance: when the silicon powder content is low, the frost resistance of the silicon powder concrete and ordinary concrete is basically the same, when the silicon powder content of more than 15% less of its frost resistance. This view been largely confirmed by a large number of tests, mainly due to more than 15% silicon powder concrete expansion increases, the relative dynamic elastic modulus lower, the compressive strength of a sharp decline from inside the concrete characteristics The specific surface area is small, the spacing factor.b) impermeability: the silicon powder particles as small as 20 to 100 times smaller than cement particles can fill the gap in the middle of the cement particles, make the concrete dense and secondary hydration of silicon powder, the resultant congestion penetration channel in the concrete, the impermeability of the silicon powder concrete is strong, the permeability of concrete increases with increasing water-cement ratio, which is relatively poor because the compactness of the water-cement ratio concrete.c) anti-chemical attack: silicon powder in concrete can reduce the content of Ca (OH) 2 to increase the compactness of concrete and effective to improve the weak acid corrosion, but not in the acid or the depth of the weak acid, because of the concrete CSH decomposition in acid, In addition, it also salt class of corrosion, chloride and sulfate, it can be the reason why anti-formate erosion, because the silicon powder concrete more dense, pore structure is improved, thereby reducing the harmful ion transmission speed and reduce the solubility of Ca (OH) 2 and calcium ettringite (3CaO · Al2O3 · 3CaSO4 · 32H2) generate the results of the hydrated calcium silicate crystals.Source:http://www.mhcmp.com

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