Is the refractory concrete a castable refractory?

July 18, 2018

Refractory concrete is an unshaped refractory,which is directly used by the refractory aggregate, powder and binders or other liquid which is not used for calcination.It is also called refractory pouring materials. Generally most of this material is constructed by pouring. So it’s also called castable refractory. It can be divided into:

1. Ordinary refractory concrete. The materials used are high alumina, clay,siliceous, alkaline materials (magnesia, chromite, dolomite etc) or special materials(carbon, silicon carbide, zicron etc), and several refractory aggregate combination.

2. Insulating refractory concrete. It is mainly made up of refractory lightweight aggregate. For example, expanded perlite, vermiculite, ceramsite, porous clay clinker, hollow alumina sphere etc, and it also be combined with several refractory light aggregates or combined with refractory aggregates. The cementing materials for refractory concrete include high alumina cement, phosphate cement, sodium silicate cement, clay etc.

The refractory concrete is a non-burning product, the production process is simple and saving energy. It can be shaped according to the demands, the integrity is better than the brick lining, it is suitable for mechanized construction, and the lining life can be prolonged when used reasonably. The refractory concrete is mainly used in industrial furnaces such as metallurgy, petroleum, chemical,building materials, machinery and other industrial kilns. The general using temperature is 1300~1600°C. The refractory concrete with a temperature lower than 900°C is called heat-resistant concrete,which is mainly used in the foundation of thermal equipment, chimneys, flue and other structures.

Performance comparison with refractory bricks

1. The refractoriness is similar to the refractory brick of the same material,but as the refractory concrete (castable) is not sintered, the shrinkage is large at the first heating, so R.U.L is slightly lower than refractory brick. Nevertheless, the overall performance is superior to refractory bricks.

2. Refractory concrete is superior to the low temperature cementing agent, and C.C.S is high. At the same time, because of the good integrity of the masonry, the gas tightness of the furnace is good and it is not easy to be deformed. The outer shell plate can be eliminated, and the performance of the furnace against mechanical vibration and impact is better than the brick masonry. For example, it is used on the side wall of the soaking furnace, where the mechanical wear and collision are relatively strong, and the service life is several times higher than of the brick.

3. The thermal shock is good, most or all of the aggregate is clinker, and the expansion is counteracted by the shrinkage of the cementing materials. Therefore, the thermal expansion of the masonry is relatively smaller than the brick, and the temperature stress is small, and there are various network, needle like and chain crystalline phases in the structure. Strong resistance to low temperature stress. For example, it is used for cast the soaking furnace inlet and furnace cover, the service life is extended to one and a half years.

4. The production process is simple and the complicated brick making process is eliminated. It can be made into various of precast blocks and mechanized construction, which greatly speeds up the construction of the furnace, and improves the efficiency of the bricklaying by more than 10 times. We can also use waste bricks as aggregate and turn waste into profit.