Castable refractory is a dry mix of refractory aggregate, binder and additives that is mixed with water and cast, poured or vibrated into shape, much like ordinary concrete but able to withstand temperatures above 1,400°C. Because it is installed as a single jointless mass, it is also called a monolithic refractory. After casting it is cured and dried, then heated to develop a hard, wear-resistant lining.
This guide explains what castable refractory is, the main types, where each is used, and how to select the right grade.
What is castable refractory used for?
Castable refractory is used to line furnaces, kilns, boilers, ladles, incinerators, and any high-temperature vessel where a jointless, custom-shaped lining is needed. It is ideal for complex shapes, repairs, and precast components because it can be poured into a mould instead of laid as bricks.
Types of castable refractory
Conventional castable
Conventional castables use 15 to 25% calcium aluminate cement as the binder. They are economical and easy to install, suited to backup linings, boilers and general furnace work up to moderate temperatures.
Low cement castable (LCC)
Low cement castables reduce cement content to roughly 4 to 8%, which lowers porosity and raises strength and hot performance. They are used for steel ladles, tundish, and demanding wear zones.
Ultra low cement castable (ULCC)
Ultra low cement castables contain under 4% cement, giving very high density and excellent resistance to slag and abrasion for the most critical high-temperature linings.
Insulating castable
Insulating castables use lightweight aggregate to give low thermal conductivity. They are used as backup insulation behind a dense working lining to cut heat loss.
How to select the right castable
- Service temperature: higher temperatures push you toward low and ultra low cement grades.
- Wear and chemical attack: slag and abrasion call for dense LCC or ULCC; backup zones can use conventional or insulating castable.
- Installation method: pouring, vibration casting, or gunning each suit different grades.
- Insulation vs strength: dense castables for the hot face, insulating castables behind them.
Frequently asked questions
What is the difference between castable and refractory cement?
Refractory cement is only the binder. Castable refractory is the complete ready-to-use mix of refractory aggregate, binder and additives, you add water and cast it into a finished lining, similar to how concrete differs from cement.
What temperature can castable refractory withstand?
It depends on grade. Conventional castables serve up to about 1,400 to 1,500°C, while high alumina low cement and ultra low cement castables can withstand 1,600 to 1,800°C in continuous service.
How is castable refractory installed?
The dry mix is blended with a controlled amount of clean water, cast or vibrated into a mould or against an anchored surface, cured, dried, and then heated on a controlled schedule to remove moisture and develop strength. Correct water addition and dry-out prevent explosive spalling.
Need help choosing a castable grade for your furnace or kiln? Talk to the Shanker Agencies engineering team with your temperature, wear and shape requirements.
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Frequently Asked Questions
What is the difference between castable and refractory cement?
Refractory cement is only the binder. Castable refractory is the complete ready-to-use mix of refractory aggregate, binder and additives, you add water and cast it into a finished lining, similar to how concrete differs from cement.
What temperature can castable refractory withstand?
It depends on grade. Conventional castables serve up to about 1,400 to 1,500°C, while high alumina low cement and ultra low cement castables can withstand 1,600 to 1,800°C in continuous service.
How is castable refractory installed?
The dry mix is blended with a controlled amount of clean water, cast or vibrated into a mould or against an anchored surface, cured, dried, and then heated on a controlled schedule to remove moisture and develop strength. Correct water addition and dry-out prevent explosive spalling.