What are the disadvantages of water-based refractory cement ?
Building refractory bricks requires refractory cement of the same material. Refractory castable cement is also configured with different grades of refractory mud according to different grades of refractory bricks. For example, when building high alumina bricks and clay bricks, 5% high-aluminum cement and refractory clay cement are prepared.
1. General refractory cement is prepared with water
Generally, refractory clay is prepared with water. The proportion of water added is between 25-30%, depending on the on-site construction conditions. If the temperature of the refractory bricks used in the furnace lining exceeds 1350°C, high-grade refractory bricks are needed, and the refractory cement requires strong plasticity to fill the gaps between the refractory bricks and enhance the strength and life of the product.
2. Disadvantages of refractory cement prepared with water
The disadvantage of refractory castable cement prepared with water is that its strength and adhesion are not as good as those prepared with phosphoric acid. Refractory cement prepared with water may cause bricks to fall off. The strength in the cold state is low and cannot be integrated quickly with the prepared refractory bricks. The setting time is also not as good as that of phosphoric acid bound refractory clay.
Refractory cement modulated with phosphoric acid has strong adhesion and good strength. It can become stronger with the refractory bricks in the masonry as the temperature increases. And when it is integrated with the refractory bricks, the bricks will not fall off when bonded with the refractory bricks.
3. Judgment criteria for refractory cement
The criterion for judging refractory castable cement is the cold bonding strength between the refractory cement and masonry refractory bricks, which has sufficient strength even when the service temperature exceeds 1350°C. There are many kinds of refractory mud mixtures, including water glass, phosphoric acid, CMC and other binding agents. The refractory cement prepared with water glass solution generates silica gel, which is suitable for use with acidic refractory bricks.
The refractory mud used with lightweight refractory bricks is also of the same material. The refractory castable cement used with clay bricks and lightweight clay bricks is the same. Also produces strength and adhesion. If it is a high-alumina brick with an aluminum content higher than 60%, high-aluminum refractory cement must be used. Refractory bricks made of corundum must be equipped with corundum refractory cement .
The refractory mud prepared by adding water does not have water glass or phosphoric acid. It solidifies quickly and does not thicken after 12 hours of storage. However, if the refractory mud prepared by water is not stored for a long time, there will be water above and mud below. Fire clay prepared with water glass or phosphoric acid aqueous solution has good fluidity and strong bonding strength.
In short, no matter what kind of refractory cement is used, it must be determined according to the refractory bricks used and the temperature. Refractory mud prepared with water or refractory mud with other binders is also selected based on specific actual conditions.
