Plastic refractory is produced by thoroughly mixing refractory aggregates, powders, binders, and functional additives with water or other liquids in controlled proportions and particle size gradation.

It can be classified as follows:

Linear Change Rate

The volume stability of plastic refractory is evaluated by its linear change rate and thermal expansion behavior.

During the initial heating stage, slight shrinkage occurs due to moisture evaporation and dehydration. With further temperature increase, controlled expansion gradually takes place. After 3–4 heating and cooling cycles, the permanent linear change becomes comparable to that of conventional fireclay and high-alumina bricks, indicating stable dimensional performance under thermal cycling.

Strength Development

Plastic refractory typically undergoes sintering at temperatures above 1200–1300°C, resulting in a significant increase in cold crushing strength.

Below 1100–1200°C, the hot modulus of rupture is generally higher than the cold modulus of rupture.

Above 1200°C, partial softening may occur in certain grades, causing the hot strength to decrease relative to the cold strength.

At temperatures exceeding 1200°C, hot and cold strength trends differ significantly due to structural transformation and phase evolution.

Thermal Shock Resistance

Compared with refractory bricks and other monolithic refractories of similar composition, aluminosilicate plastic refractory exhibits superior thermal shock resistance.

This performance is attributed to:

The absence of abrupt crystal phase transformation during heating and service, reducing structural stress.

A microstructure near the hot face composed primarily of mullite and cristobalite microcrystals with a relatively low glass phase content.

A gradual transition in phase composition and physical properties from the hot face to the cold side, minimizing thermal stress concentration.

Common Types

Commonly used plastic refractory include:

Fireclay-based

High-alumina

Corundum-based

Service Temperature

The service temperature of plastic refractory depends on the material composition:

Fireclay plastic refractory: 1300–1400°C

Premium fireclay grades: 1400–1500°C

High-alumina plastic refractory: 1500–1600°C

Corundum-based plastic refractory: 1500–1900°C

Installation & Dry-Out Requirements

To ensure proper dehydration during baking:

Vent holes with a diameter of 3–6 mm should be pre-drilled at intervals of 100–150 mm on the hot face.

The hole depth should be approximately two-thirds of the lining thickness.

Expansion joints 1–3 mm wide and 50 mm deep should be provided at intervals of 1000–1500 mm to accommodate thermal expansion and contraction.

Plastic refractory generally does not require traditional curing. However, due to the presence of water-soluble additives, the surface should be covered with plastic film immediately after installation to prevent premature moisture loss and cracking.

During the baking process, the temperature should be increased gradually, typically at a rate of 30–50°C per hour, especially:

Below 200°C (moisture removal stage)

Around 800°C (phase transformation stage)

Slow heating at these stages helps prevent structural damage.

Lining Structure & Construction Method

Plastic refractory linings are installed by ramming and anchoring, forming a dense monolithic working layer.

Gaps between anchor bricks or hanger bricks are filled with plastic refractory material.

Compaction is performed using a pneumatic hammer or tamping machine.

Installation is carried out continuously in layered sections, including the furnace bottom.

The surface is roughened, vent holes are punched, and expansion joints are cut as required.

Performance & Service Life

Plastic refractory linings offer:

Strong structural integrity

Excellent sintering performance

High strength at elevated temperatures

Due to these characteristics, the lining resists peeling and spalling during operation. Under normal working conditions, the service life can reach approximately 10–15 years, depending on operating parameters.

Steel: Linings for hot blast stoves, converter ducts, and ladle preheaters.

Non-ferrous: Electrolytic cells, smelting converters, roasting furnaces.

Building materials: Cement kilns, glass regenerators, ceramic kilns.

Chemical: Reactors, pyrolysis units, gasifiers.

Power: Boilers, combustion zones, waste incinerators.

1. Substrate Preparation

The substrate surface must be thoroughly cleaned prior to installation. Ensure that it is free from dust, oil, loose particles, and other contaminants. Any cracks, spalling, or surface defects should be repaired in advance to provide a sound base for application.

2. No Water Addition

The material is supplied ready for use. Do not add water or adjust the consistency on site, as this will significantly reduce bonding strength and overall performance.

3. Layered Ramming

Adopt a layered installation method to ensure dense compaction. Each layer must be thoroughly tamped to prevent internal voids and structural looseness.

4. Treatment of Corners and Irregular Areas

Extra care should be taken at corners, furnace doors, burner blocks, and other irregular sections. These areas must be compacted carefully to ensure tight bonding with the substrate and uniform density.

5. Post-Installation Curing

After installation, allow the material to cure under static conditions. Avoid vibration, mechanical disturbance, or premature heating during this period.

6. Controlled Heating Schedule

The initial dry-out and heating process must follow a controlled temperature ramp-up. Heating should be gradual to prevent cracking or peeling caused by rapid temperature changes.

Q1: What are the main differences between plastic refractory and refractory castables?

A: Plastic refractory is supplied ready for use and does not require water addition, offering greater flexibility during installation. It is particularly suitable for complex structures and repair applications. Refractory castables, on the other hand, are better suited for large-scale integral casting and monolithic linings.

Q2: Can plastic refractory be used in high-temperature applications?

A: Yes. Different material systems-such as fireclay, high-alumina, or corundum-based grades-can be selected according to the required service temperature to meet high-temperature operating conditions.

Q3: Is special equipment required for installation?

A: Generally, no large-scale equipment is required. Installation is typically carried out by manual or mechanical ramming and tamping.

Q4: What should be done if the product is damaged during transportation?

A: We reinforce all packaging to minimize transportation risks. If damage is found upon receipt, please provide photos, videos, and relevant shipping documentation within 48 hours. After verification, we will arrange free replacement of the damaged goods or provide an alternative solution through mutual agreement.

Q5: What is the shelf life and recommended storage method?

A: Under proper storage conditions-cool, dry, well-ventilated, protected from direct sunlight and rain, and with intact packaging-the shelf life is 6 months.
Keep the product away from flammable materials and store different batches and grades separately to avoid mixing.

Q6: What information is required for product customization?

A: For customized solutions, please provide the following:

Kiln type (e.g., rotary kiln, blast furnace)

Application location within the kiln

Maximum operating temperature

Contact medium (slag type, flue gas composition, etc.)

Kiln dimensions or required lining thickness

Preferred installation method

Our R&D team will optimize the formulation accordingly to ensure the product meets your operational requirements.

Q7: Do you support OEM/ODM cooperation?

A: Yes. We fully support OEM and ODM partnerships and offer flexible solutions ranging from customized production to integrated technical services.

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