| The main components of the calcium silicate board is calcium silicate hydrate, which was synthesized by siliceous material and calcium materials under the condition of high temperature and high pressure. Calcium silicate board has many advantages of high strength, low thermal conductivity, high heat-resistant temperature and safety in use. It is widely used in separation wall, ceiling, firewall, floor board, and thermal insulation wall. But it also has many problem in practical application:high breakage rate, poor surface smoothness, high water absorption rate, poor weather resistance. So the modification on the performance of the calcium silicate board is extremely urgent.Calcium silicate hydrate was prepared via pre-reaction under ambient pressure and autoclave curing with silicon dioxide, calcium hydroxide and portland cement as raw material. The effect of rate of Ca/Si, temperature and time of autoclave curing on composition of calcium silicate hydrate and the performance of calcium silicate board was studied by XRD, FTIR, TG-DSC and SEM. The corrosion resistance and alkali corrosion resistance mechanism of rock wool compared with that of alkali resistant glass fiber in alkali solutions was analysed by SEM and EDS. At the end, the toughening and reinforcing effect of content and kinds of rock wool and paper fiber on property of calcium silicate board were examined by electronic universal testing machine. The results were as below:(1) Tobermorite was synthesized at the temperature of 180℃ for 8h while the rate of Ca/Si is 0.83 or 1.0, and the degree of crystallinity and quantity is more when it was synthesized for 20h by analysis results of XRD. From 0.83 to 1.5 of Ca/Si, bending strength rise and then go down with a maximum of 16MPa at Ca/Si=0.83 at 180 ℃ and 20h.(2) The result of accelerated aging test in saturated limewater at the temperature of 80 ℃ from 1 day to 12 day indicated that:mass loss rate of glass fiber was up to 22%with an squamous appearance; but the mass of the three rock wool remained about the same with smooth surface. The result of rock wool and glass fiber were corroded in saturated limewater by hydrothermal reaction at 180℃ for 20h turned out that:glass fiber peeled from the filament surface on some areas, whereas on other areas the shell is still bonded to the fiber core; rock wool is characterized by different morphology substance on the surface. The analysis of EDS and SEM demonstrated that the reticular structure (Si-O-Si) inside the fiber was damaged by reaction between cations inside fiber and OH" in saturated limewater.(3) The influence of paper content on calcium silicate board indicated that:from 0% to 8% of paper fiber, the strength of the board decreased gradually; but the toughness increased obviously. The influence of rock wool content on calcium silicate board indicated that:from 0% to 8% of paper fiber, the strength of the board go up and then go down with a maximum of 17MPa at 4% without toughness. calcium silicate board were up to a relatively higher bending strength 16MPa with 4% paper fiber and 4% rock wool fiber, and it had a better toughness. At the same time the two fiber inside the calcium silicate board had improved the performance of freezing and thawing resistance according to analysis data of tests. |
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