Self-flowing castable is a castable refractory material that can flow and degas without vibration. Its characteristic is that without reducing or significantly reducing the performance of the castable, it can be cast into various shapes of construction bodies without vibration by adding appropriate water. Self-flowing castables are especially suitable for thin-walled or complex-shaped parts that cannot be vibrated for molding.
Self-Flowing Castable Characteristics
Self-flowing castables are high-performance castables developed based on the principles of rheology, solid fluids, and close packing. Self-flowing castables are developed on the basis of low-cement and ultra-low cement castables. It is composed of refractory aggregates, powders, and high-efficiency dispersants with a certain particle size gradation. The key is the rational use of ultrafine powder particle size, quantity, and efficient dispersant so that the castable can self-flow and automatically spread.
Self-flowing castables have the following advantages compared with vibrating castables.
①. Can flow under its own weight without vibration.
②. It can automatically spread and reach parts that cannot be reached by vibrating castables.
③. It can be pumped for construction, reducing labor intensity and speeding up the construction cycle.
④. Reduce construction noise pollution.
At present, the main indicator for evaluating the workability of self-flowing castables is fluidity. The better the self-flowing performance, the greater the flow value. Factors that affect the flow value include particle shape, particle gradation, and the amount of dispersant added. Different from vibrating castables, the particle composition of self-flowing castables has a narrow range of coarse, medium, and fine proportions. Beyond a certain range, it does not have self-flowing characteristics.
How does the Self-Flowing Castable Achieve Its Fluidity?
Self-flowing refractory castables mainly rely on the dispersant inside to increase the fluidity of the castables, thereby achieving the self-flowing effect. Dispersants are generally divided into two categories: inorganic dispersants and organic dispersants. Commonly used inorganic dispersants include silicates, such as water glass. and alkali metal phosphates, such as sodium tripolyphosphate, sodium hexametaphosphate, and sodium pyrophosphate. Organic dispersants include triethylhexyl phosphate, sodium lauryl sulfate, methylpentanol, cellulose derivatives, polyacrylamide, gur gum, fatty acid polyethylene glycol esters, etc.
Self-Flowing Castable Refractory directly from RS Factory
The commonly used fluidity evaluation method of self-flowing refractory castables is measured by fluidity (value).
The construction of self-flowing castables is much more convenient than traditional castables, and the equipment used is roughly the same, but self-flowing castables do not require vibrating rod vibration. The mixing equipment generally uses a powerful mixer, and the conveying equipment can use a lifting container. However, pressure-feeding technology is currently used more often. This technology makes transportation more convenient and faster and reduces the workload of operators. Since self-flowing castables have very good fluidity, a mold structure with good sealing performance and high structural strength is required to prevent material leakage during construction. In addition, self-flowing castables must not lose water, otherwise the flow performance will be affected. Therefore, the surface of the wooden mold that is in contact with the self-flowing castable should be oiled.
When pouring self-flowing castables, you only need to pour the mixed materials into the site to be constructed. There is no need to vibrate with a vibrator. The self-flowing castables can flow and spread out by their own gravity. The curing, drying, and baking after pouring are the same as traditional castables of the same material.
Application of Self-Flowing Refractory Castables
Self-flowing refractory castable is a new construction method of refractory castable developed in the past ten years. It is innovative on the basis of low cement series refractory castables. It is developed on the basis of the most closely related mechanical principle of solid state and rheology theory. This kind of castable is mainly used in thermal equipment such as when the lining is thin and difficult to construct or repair the lining, and has significant economic benefits. At the same time, it has been used in thermal equipment such as ladles and tundishes, blast furnace tap trenches and slag trenches, boiler tube protective layers and incinerator grates, heating furnaces, and cement kilns, and the results have been remarkable.
The development of refractory castables mainly involves the critical particle size and particle gradation of refractory aggregates, binders, and admixtures. The use of ultrafine powder technology started a generation of low-cement series refractory castables. The use of nanotechnology in the future will change the face of castables. The critical particles of the refractory aggregate are enlarged to about 25 mm, which greatly extends the service life of the ladle refractory castables. Self-flowing refractory castables can self-flow and have good performance, and they also follow the above principles. There are several main measures: appropriate aggregate particles and particle gradation, appropriate binders and water-reducing agents, and appropriate water consumption. The main products include corundum and high alumina self-flowing refractory castables, and self-flowing refractory castables for heating furnaces. Self-flowing refractory castables are used in tundish and ladle, and self-flowing refractory castables are used in tap troughs. Self-flowing refractory castables used in other thermal equipment.
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