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Refractory castable construction Precautions

May 20, 2020

        Refractory castable is a kind of granular and powdery material made of refractory material with a certain amount of binder.With high fluidity, it is suitable for irregular refractories formed by pouring.Compared with other amorphous refractory materials, the binder and moisture content is higher, so the fluidity is better, but the wear resistance is poor, suitable for all kinds of kilns, with alkali resistant hydraulic hard castable.Due to the characteristics of refractory castable itself, it has strict requirements in construction.The details are as follows:

1. Clean water shall be used for mixing refractory castables.

2. The formwork used for casting shall have sufficient rigidity and strength, and the dimension of the supporting formwork shall be accurate and shall prevent deformation in the construction process.The joint of formwork should be tight and not leak.Anti-stick measures should be taken for the template.The surface of insulated masonry in contact with castable shall be waterproofed.

                                                                                          refractory castables

3. The castable shall be stirred by a forced mixer.Mixing time and amount of liquid shall be performed according to the construction instructions.When changing the material grade, the mixer, hopper and weighing container should be cleaned.

4. The mixed refractory castable shall be poured within 30min or within the specified time according to the requirements of the construction instructions.The castable which has already been set shall not be used.

5. The installation of expansion joints for the whole cast refractory lining shall be in accordance with the design regulations.If not specified, the following data can be used for the average value of each meter of lining expansion joint: 4 ~ 6mm of clay refractory castable;High alumina cement refractory castable is 6 ~ 8mm;Phosphate refractory castable is 6 ~ 8mm;The water-glass refractory castable is 4 ~ 6mm and the Portland cement refractory castable is 5 ~ 8mm.

6. The casting of refractory castable shall be carried out continuously.Before the initial setting of the front layer of castable, the second layer of castable shall be filled;If the interval exceeds the initial setting time, it shall be treated according to the requirements of construction joints.

7. The refractory castable shall be maintained in accordance with the design method after construction.During maintenance, no external force or vibration shall be suffered.

8. Open mold.No load-bearing formwork shall be removed only when the strength of the castable ensures that its surface and edges and corners are not damaged or deformed by the moulds.The load-bearing formwork shall not be demounted until the castable has reached 70% of the designed strength.The hot and hard castable shall be baked to the specified temperature before the mold can be folded.

9. There shall be no spalling, cracks, holes and other defects on the surface of casting lining.Slight network cracks are allowed.

10. Prefabricated parts of refractory castables should not be stored in the open air.When stacking in the open, measures should be taken to prevent rain and moisture.