Magnesite fire-resistant panels are mainly used for the decoration of building ceilings, internal partition walls and other parts requiring fire protection. At present, the magnesite building fireproof board produced by machinery has both the light weight and flexibility and reworkability of wooden organic board, and the fireproofing and water resistance of inorganic board. At present, many large projects in our country have used magnesite building fireproofing boards for decoration.
For many years, problems such as moisture absorption and halogen return, plate warpage, embrittlement, and small pores on the surface during mechanical production of magnesite building fire-resistant sheet have affected the quality of the product. The surface of magnesium building fire-proof boards absorbs moisture and returns to halogen, which causes the problem of rework of decoration works. Some boards are very wet on the surface after two days of decoration, and water droplets are formed on the surface within three days, making it difficult to carry out secondary decoration.
There are two main measures to solve the malady of the magnesite building fire-proof board: one is to minimize the free MgCl2 in the product to reduce it to a certain extent, and the product loses its ability to absorb moisture. This requires a good formula. Implement good conservation technology. The second is to add a highly effective anti-hygroscopic re-halogen additive in the product production process. This additive can form a thin water-repellent film on the capillary wall, pores and cavity walls inside the product and the outer surface of the product, preventing The transmission of moisture in these parts prevents the product from absorbing moisture and returning to halogen.
The main reason for the deformation of magnesite building fireproof board is its poor volume stability. Such products generally have large format, small thickness, and large deformation value, which affects the construction quality of the project. The main disadvantages in engineering are the seam at the splicing place of the plate and the phenomenon of warping and bulging on the large surface. There are many reasons for the deformation of magnesite building fire-proof boards, mainly due to poor product maintenance and insufficient hardening during production.
The magnesite cement used in the production of magnesite building fireproof board is an inorganic cementitious material. One of its characteristics is that it must have appropriate temperature and humidity and a certain hardening time after molding, so that it can fully conduct chemical reactions to give the product excellent quality. Physics, mechanics and durability.
After the product is formed, it must be placed in an environment suitable for temperature, humidity and sufficient curing time. On the contrary, the hardening process does not proceed well, the amount of hardened products in the product is insufficient, and free MgO and MgCl2 exist in large quantities. Once the appropriate temperature and humidity are encountered during the use of the board, the internal chemical reaction of the board restarts, and the internal There will be a large expansion of internal stress. In addition, if the sheet is not well maintained, the volume stability will inevitably be poor, and there will be a lot of free moisture inside. When it encounters a dry environment, it will generate shrinkage and cause shrinking internal stress. These two kinds of internal stress damage forces are very large, often causing engineering quality accidents.
There are many reasons for warpage and deformation of magnesite building fire-resistant panels, such as the raw materials failing to meet the target requirements, the lack of good product formulas, the poor selection of modifiers, and no reasonable process parameters. As long as the reasons for the deformation of the plate are grasped and measures are taken accordingly, the disadvantages of warping and deformation of the plate are not difficult to overcome.
The brittleness disadvantages of magnesite building fire-resistant boards are: the board has good toughness in a short time when it is produced, and the whole sheet can be rolled into a tube, but it becomes very brittle after a longer period of time. Off. If it is fixed on the keel, in the suspended place, a hole is broken with a sharp instrument, and the cross-section of the plate can not see a situation similar to the broken wire. There are two main reasons for the embrittlement: First, high-alkali fiber cloth, that is, clay crucible cloth, is used in the production of boards. This reinforcing material is quickly corroded and gradually lost in the alkaline environment of magnesite cement. Strength, so no trace of fiber of magnesite building fire board can be seen in the section of the board. The second is the brittleness of magnesite fire-resistant construction boards due to improper formulation of the board production. In the category of inorganic cementitious materials, the toughness of magnesia cementitious materials is unmatched by other materials. When toughening measures are taken, the toughness will increase significantly.
There are three measures to address this ill:
(1) Add vibration facilities to the molding machine, and use vibration to eliminate air holes in the cement.
(2) Rolling measures are implemented on the machine, that is, a height-adjustable rolling rod is added on the bottom support plate and the cloth.
(3) Select a reasonable slurry formula, use a defoamer to eliminate air bubbles in the slurry, and control the slurry's fluidity.
There are many process parameters to be controlled on the magnesite building fireproof board production line. To strictly control these process parameters, we must overcome the phenomenon of slab withdrawal. Only in this way can we stabilize production and ensure the quality of the board.
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