Unshaped Refractories products

ISO 1927-1 2012. Monolithic (unshaped) refractory products - Part 1 Introduction and classification. 

Monolithic linings are a relatively recent development and consist of unshaped refractory products [3]. There are two basic types of monolithic linings castable refractory and plastic refractory. 

Initially, when unshaped refractories were first used, the property requirement was kept the same as for shaped refractories, in thatthey mainly replaced linings. Later on, when the use of these refractories became widespread, new standards had to be developed. The first standards on unshaped refractories by the American Society for Testing of Metals (ASTM) were published in 1943 [3]. They were numbered as C 179 and C 181 C 179 covered "drying and firing linear change of plastics and rammings" and C 181 dealt with "workability index of plastic refractories." As noted earlier. World War II saw an increase of about 35% in unshaped refractory production. Specifications were required to obtain the required items from many manufacturers. 

To achieve easier communication and trading within the European community, there was a need to create European standards that was recognized in the mid-1980s. Refractories were also included in these standards. The standard for unshaped refractory products was numbered EN 1402. 

Various terms such as mixes, refractory mixes, ramming mixes, and monolithics are included in the definition of unshaped refractory products. These products are distinguished from bricks, which have a definite shape, are prefired, and are laid. Unshaped refractories are placed in larger sections. For example, a furnace lining consists of unshaped refractories. They have few joints. 

There are four types of bond used for making unshaped refractory products ... 

Apart from the four main subdivisions of unshaped refractory products, a few others are also used. They are enumerated in the following sections. 

ISO R1927 gives the subdivision of unshaped refractory products according to chemical composition. The various classes of these materials are listed in the following sections. 

Carbon-containing products are those unshaped refractory products containing more than 1% carbon. 

The definition of unshaped refractory products mentioned that these products may contain fibers. The addition of various fibers to these products will be discussed further in the following sections. 

Table 1 Highlights Regarding the Development of Unshaped Refractory Products...

Figure 1 Subdivision of unshaped refractory products schematically.

The consumer is confronted with a confusing number of manufacturers and products with more or less fancy names. However, names or designations are not always in agreement with the performance capability of the refractory product and what is expected. Consequently, the Verein Deutscher Eisenhiittenleute (VDEh) (Association of the German Iron and Steel Engineers) published a code number key for unshaped refractory products. This code number key is provided in the form of a standard titled Stahl-Eisen-Werkstoffblatt 916 (SEW) and was universally accepted and applied by all concerned German-speaking countries (8). 

Table 6 Product Code of the VDEh for Unshaped Refractory Products (according to SEW 916)...

The multitude of refractory aggregates (for example, calcined clay, flint clay, andalusite, mulhte, bauxite, fused white or brown alumina, sintered alumina, etc.) and the different grain sizes of these materials—in addition to the big variety of bonding agents, additives, and mixing liquids—enable endless combination possibihties in development work on unshaped refractory products. Therefore, a qualitative standardization is not really possible as it is the case for refractory bricks. As a result of the ENV 1402-1 standard, which now provides a more precise definition of the products, there will probably be adjustments on the market in the long run. If also considering economic aspects, suitable products will obviously be developed on the basis of all the available constituents. 

As mentioned before, the maximum service temperature for steel fibers under normal conditions is approximately 1200°C. Therefore, attempts have been made to reinforce unshaped refractory products with ceramic fibers in order to achieve positive effects at even higher temperatures. 

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