The aggregate particles of self-flowing castables are spherical, and the construction method is pumping. It relies on its own gravity to flow and degas, so it is called self-flowing castables. Because the aggregates of self-flowing castables are spherical and have low water absorption, a suitable proportion of water reducer is added during construction to improve thixotropy, reduce the viscosity of the mixture, and enable the castable to flow freely. It is especially effective when used in areas where the kiln lining is thin and difficult to construct or repair. It is widely used in thermal equipment such as ladles, tundishes, iron trenches, slag trenches, boiler tube protective layers, incinerator grates, heating furnaces, cement kilns, etc.
Maintenance Process Points and Quality Requirements of Self-Flowing Castables
Self-flowing castables are a type of castable refractory material that can flow, degas, and level without vibration. Its characteristic is that it can be cast into various shapes of construction bodies without vibration by adding appropriate water without reducing or significantly reducing the performance of the castable. Self-flowing castables are particularly suitable for use in thin-walled or complex-shaped parts that cannot be vibrated. During the maintenance of CFB boilers, the maintenance process points and quality requirements of self-flowing castables have the following precautions.
Construction of Self-Flowing Refractory Castable
Inspection of self-flowing castables
Technical points: 1. Check and record the erosion and wear of self-flowing materials and defects such as cracks and shedding. 2. Check the compactness of the refractory and wear-resistant layer.
Quality requirements: 1. The depth and width, surface shedding thickness, shedding area, etc. cannot exceed the specified values. 2. There should be no defects such as non-compactness and holes.
Removal of self-flowing castables
Technical points: 1. Use a colored pen to mark the area to be removed. 2. Remove the non-heating surface area with tools such as electric hammers and hammers.
Quality requirements: 1. Clear and correct marking. 2. Clean; the joint surface is straight.
Mixing of self-flowing castables
Technical points: 1. Water quality should be qualified. 2. Water temperature and ambient temperature meet the requirements, otherwise, measures should be taken. 3. After the packaging bag is opened, it should be used immediately. 4. Dry mixing. 5. Add water and mix according to the manufacturer’s requirements. 6. Record each mixing.
Quality requirements: 1. Water quality and water temperature meet the requirements; 2. Mixing time should meet the manufacturer’s specified time, and the time from adding water and mixing to the completion of pouring should not exceed the manufacturer’s specified value. 3. Mixing records are complete. 4. The mixer should be cleaned every time the material is mixed.
Formwork production and installation of self-flowing castables
Technical points: 1. Carry out wooden mold layout, material cutting, and production according to the design and combined with the actual site. 2. Before supporting the mold, check whether the welding position, number, and shape of all grabbing nails are correct. Check whether the plastic caps of all grabbing nails are complete. For grabbing nails without plastic caps, asphalt paint should be applied on the top. 3. Before supporting the formwork, the debris on the formwork and its upper area should be cleaned up. 4. After the formwork is supported, pouring should be done immediately.
Quality requirements: 1. The production size is correct and meets the design requirements; 2. The formwork is installed firmly and the joints are tight.
Casting of self-flowing castables
Technical points: 1. Before pouring, the template size should be carefully checked. 2. The mixed material should be poured into the template immediately.
Quality requirements: 1. The pouring size meets the design. 2. The pouring time meets the manufacturer’s requirements.
Demolding inspection of self-flowing materials
Technical points: 1. Check the casting quality after demolding. 2. Perform maintenance.
Quality requirements: 1. The interval time from pouring completion to demolding cannot be less than the time specified by the manufacturer. 2. After demolding, the surface should be free of defects such as cracks, depressions, honeycombs, holes, etc. 3. Maintenance meets the manufacturer’s requirements.
Rongsheng Self-flowing Castable Manufacturer
Self-flowing castable is developed on the basis of low-cement and ultra-low-cement castable. The key is the reasonable use of ultrafine powder particle size, aggregate shape, and high-efficiency dispersant, so that the self-flowing castable can flow and spread automatically, achieving the effect that vibration-type castable cannot achieve. The fluidity of self-flowing castable depends on the particle size composition and liquid phase, that is, the friction of aggregate and the viscosity and yield of slurry. The performance of self-flowing castable does not require vibration, pounding or hitting the outer mold. The key to self-flowing is to reasonably select aggregate particles and particle grading, binder, and the appropriate amount of water to determine. Unreasonable particle grading will lead to reduced self-flowing. Self-flowing castable is a mixture of powder and water into a pure slurry; fine aggregate is suspended in the pure slurry to become mortar; finally, coarse aggregate is suspended in the mortar to become self-flowing castable. Self-flowing castable contains less aggregate and more powder, less direct contact between aggregate particles, fine powder and water form a continuous fluid, and flows by itself under the action of gravity, which is why self-flowing castable can flow by itself.
