On-site construction methods of castables

1. Construction preparation

(1) Refractory castables, heat insulation products, various anchor bricks, hanging bricks, metal hanging parts, filling materials for expansion joints and horizontal sliding joints, and lubricating materials for anti-sticking formwork should be classified and put away for easy use.

(2) The formwork used for pouring requires a smooth surface and sufficient rigidity and strength. The formwork should be firm and the size should be accurate. Displacement and deformation during construction should be prevented. The formwork joints should be tight and no slurry leakage. The surface of the formwork is pasted with plastic or coated with lubricating material.

(3) The steel bars or metal traces, hardware, and hanging parts buried in the pouring body should be located on the non-heating surface. The service temperature of the steel bar should not exceed 350 ℃. The metal tracer should be welded firmly at the design position, and check whether there are guns by tapping with a hammer. Those who fail to pass must be re-welded bitumen.

(4) Anchor bricks and hanging bricks must be inspected one by one in advance, and those with excessive cracks or serious damage outside the groove cannot be used.

(5) The construction equipment is ready for installation and should be cleaned. The refractory castable should adopt forced stirring. The mixer should be placed close to the construction site with water and electricity. When mixing a small amount of castable, it can also be mixed by hand. The vibrating machine should use a plug-in vibrator (vibrator) or a flat vibrator. In special cases, manual tamping can be used.

(6) Reserve two or more vibration machines.

2. Stir

(1) Dry mixing

Pour the bagged castables into the forced mixer at a rate of no more than 20% of the rated capacity of the mixer each time (if the aggregate and the binder are packaged separately, it should be noted that they must be poured in at the same time) and dry mixed for 1-2 minutes.

(2) Add water and stir

Add about 90% of the required water first, and stir evenly for 2-3 minutes. The remaining water volume is adjusted according to the situation. If it is necessary to continue to add water, after adding water and stirring for 1-2 minutes, the material can be discharged for pouring. The mixing water should be clean water, and sewage, seawater or water containing impurities should not be used.

(3) Judgment of water content

In order to judge whether the moisture content of the stirring is appropriate, a simple "hand kneading into a ball" test method can be used: take the stirring water and knead it into a tight ball, throw the ball about 30cm high, and then catch it with your hands. If the pellets deform without stopping, it means that the water content is just right; if the pellets are deformed and flow out from the hand seam, it means that the water content is too much; if the pellets crack and fall apart, it means that the water content is too little. Since the water content (water-cement ratio) directly affects the quality of the cast body, it is advisable to minimize the amount used under the condition of meeting the construction requirements.

3. Pouring construction

(1) The sundries in the mold should be removed before pouring. Set and fix the furnace shell insulation layer of expansion joint filling material, and build insulation bricks.

(2) Fill the stirred castable into the mold and vibrate. The thickness of the pavement depends on the type and specification of the vibrator used. When using a vibrating rod, the thickness of the material should not exceed 1.25 times the length of the active part of the vibrating rod; When using a flat vibrator, its thickness should not exceed 20cm. The vibrating rod should be slowly inserted into the pouring body, and the vibrating rod should be moved when the surface of the pouring material is in a flowing state. The moving speed is 1-2 m/min. The moving distance of the vibrating rod should not be greater than 1.5 times of the radius of action (the radius of action is generally about 20cm). When the vibrating rod is pulled out, the speed should be slow. When the rod head is close to the surface, it should stay for a few seconds to make the surface smooth. The vibration duration of the vibrating rod at each position should not be too long, otherwise it is easy to cause breakage, and it is generally advisable to control it within the range of 4 to 5 minutes.

(3) The pouring starts from the bottom of the furnace wall, and goes up layer by layer and block by block. Each layer starts at the corner. During pouring, it is necessary to prevent the formwork from being squeezed, which will affect the construction quality.

(4) When pouring the furnace wall, after pouring a certain height, it is necessary to lay a layer of horizontal sliding joint filling material (linoleum paper in general), and then continue pouring. When pouring the furnace roof, the required thickness must be poured at one time without layering pouring.

(5) The expansion joint value and its distribution position and structure of the integrally cast refractory castable lining shall be specified by the design. When the design does not specify the value of the expansion joint, the expansion joint can be left according to the linear expansion rate of the material. Generally, an expansion joint of 8mm-10mm is left every 2 meters, and it is kept vertically through. During construction, the filling material in the expansion joint should be fixed to avoid displacement of the filling material or being pressed across by the castable material during the construction process, so that the castable material enters the filler material, expanding the expansion joint, and the furnace gas is too wide during production. Expansion joints emerge, deteriorating the environment and wasting energy. It is best to use the "furnace body expansion plate" produced by a professional manufacturer and used in conjunction with the castable. Between the two expansion joints, 1-2 expansion lines can be left, and the depth of the expansion line is 1/3 of the thickness of the furnace lining. -1/2, the width is 2mm. When leaving expansion joints, care should be taken to stagger the holes on the furnace body and the anchor bricks. When pouring the expansion filling material, vibrate alternately from two links to keep it vertical as much as possible.

(6) The pouring material should be constructed continuously. If it cannot be continuously constructed due to various reasons, construction joints can be left. It is best to leave the construction joints at the expansion joints. The cross groove is about 20mm, and the spacing is about 100mm.

(7) When pouring the furnace body with anchor bricks, it is best to wait for the pouring construction to be slightly higher than the lower surface of the anchor bricks (about 2cm higher), and then hang the anchor bricks, so as to ensure that the anchor bricks appear below and are close to the castable Combined, it is easy to ensure the levelness of the mis-fixed bricks.

(8) When pouring the furnace roof with anchor bricks, in order to ensure the verticality of the hanging bricks and the anchor bricks will not float when vibrating, the anchor bricks should be fixed with wooden wedges before pouring. Vibration is appropriate.

(9) If the self-flowing castable is used, it cannot be vibrated for a long time during construction. It only needs to be vibrated with a vibrating rod or stirred with a wooden stick. If it is used in places where the water-cooled pipe is bandaged or vibration is inconvenient, you can use a wooden hammer to tap the template.

(10) If the self-flowing material is used for wrapping the water-cooling pipe, the insulation fiber on the water-cooling pipe should be wrapped with plastic cloth and transparent glue before construction to ensure the fluidity of the self-flowing material and not being absorbed by the fiber during construction.

(11) Necessary insulation measures should be taken during construction in winter. The temperature of the construction site and its surroundings should not be lower than 5°C. The mixing water should be heated, and the water temperature should not exceed 50°C. Stirring time should be extended appropriately.

4. Maintenance and demoulding

(1) Maintenance: The refractory castable must be cured after pouring and construction. The winter maintenance should be above 5°C, and measures should be taken to keep warm when the temperature is below 5°C.