1 Introduction
The requirements of the industrial environment on the performance of refractory materials have been continuously improved. In the past few decades, high-density anti-flocculent castables have been developed and improved. Technological progress has brought better overall performance, but the construction performance of materials is still susceptible to influence. Construction is the key to ensuring the best performance of the material. Low-cement castables are composed of coarse aggregates, fine fillers, one (or more) binders and a variety of additives, here specifically refer to active compounds.
(1) Give names to a series of mixed and additive products used in the refractory industry;
(2) Design and add functional materials and study their performance after combining with calcium aluminate cement;
(3) Explain the problems faced by the refractory industry when using amorphous materials by converting shared knowledge into product forms.
Castable formula, chemical properties and particle size are very important for refractories, but the additive system is also critical because it affects construction performance, hardening kinetics and drying performance.
The designed active compound can provide more functionality, including rheological modification, hardening mechanical principle and easier drying properties. Calculated by weight (0.1%~2.5%), they only account for the smallest part, but they have the greatest impact on construction performance.
2 Products and performance
The active compounds are obtained in different places, and have the main functional properties after adding low cement castables.
Key functions: accelerated silica fume castable vulcanizer; alumina/al-mg/al-sp vulcanizer; solidification stability at different temperatures; accelerated castable setting time; enhanced permeability; deflocculation of CMA72 products.
Typical addition amount (easy to mix 1% additives; high dose 2.5% additives; high activity 0~0.1% additives)
2.1 Deflocculant used in castables containing silica fume
The first active compound is REFPAC100, developed in 2015, to improve the construction performance of low-cement castables containing silica fume. The designed dosage is 1%. The main advantages of the compound are qualitatively related to high temperature, such as the quality of silica fume, the quality of raw materials (impurities in the fine powder), and changes in ambient temperature.
2.2 Deflocculants used for high-aluminum and low-cement castables
REFPAC500 is a deflocculant used for high alumina and containing alumina, magnesia or magnesium spinel. In addition to low water demand, it also has high fluidity. The solidification time of the product is little affected by the surrounding temperature, because it starts the hardening mechanism at low temperatures and has little effect on high and low temperatures. Some of the results shown indicate that it has better temperature stability than the currently used reference material.
2.3 Enhance the permeability of the deflocculant to promote drying
REFPACMipore20 is a powder that is easy to add to the dry mixture. It will change the usual hydration process of calcium aluminate cement, resulting in the formation of a gel-like microstructure to provide higher permeability. The castable after drying at a temperature of 110°C lower than that of the traditional fiber (approximately 150°C) has a visible change. Allows a substantial reduction in the internal pressure of the material and develops a safer and faster drying system.
3. Conclusion
The formulation of the active compound is simple, and the method provides higher flexibility and a smaller footprint. Manufacturers can load the products into trucks together with Secar71.
Low-cement castables need suitable additives to achieve superior construction performance and use performance. According to this method, some additives have been developed, such as REFPACF461 (the summer version of REFPAC100), which extends the use time of 1h at 40°C; the accelerated version of REFPAC500 (PP305), which has a shorter demolding time; and an improved version of REFPAC100 ( PP306) has a better anti-carbon flocculation effect.
