In high-temperature industrial furnaces, metallurgical equipment, and heat treatment units, the quality of refractory material construction directly affects the furnace's lifespan and operational safety. Even the highest quality refractory materials can suffer from spalling, cracking, and delamination if improperly constructed. Therefore, mastering the standardized construction process and precautions for refractory materials is crucial for ensuring stable furnace lining performance and extending service life.

I. Main Types of Refractory Material Construction

Refractory material construction methods are generally divided into three categories based on the material's form:

Refractory Brick Construction: Used for shaped refractory materials, such as high-alumina bricks, clay bricks, and magnesia bricks.

Refractory Castable Construction: Used for unshaped refractory materials, such as castables, plastics, and spray coatings.

Refractory Ramming Mixture and Spraying Construction: Suitable for furnace bottoms, furnace lining repairs, and curved surfaces.

Different construction methods for different materials have their own key points, but the overall construction process is generally similar.

II. Refractory Material Construction Process

1. Construction Preparation Stage

(1) Design Review and Material Acceptance: Verify drawings and technical requirements, and check the model, batch, packaging, and factory inspection report of the refractory materials.

(2) Construction Environment Preparation: Keep the construction site dry and clean; the ambient temperature should generally be above 5℃, and the humidity below 85%.

(3) Tool and Equipment Preparation: Include mixers, vibrators, thermometers, drying equipment, etc., ensuring they are in good condition.

2. Substrate Treatment

Before construction, clean debris, rust, and oil stains from the furnace body or steel shell to ensure the construction surface is flat and dust-free. If necessary, apply an interface agent or moisture-proof layer to enhance bonding strength.

3. Material Mixing and Batching

For castables, plastics, and other unshaped refractory materials, the water addition and mixing time provided by the manufacturer must be followed. Generally, mechanical mixing is used for 3-5 minutes to ensure the slurry is uniform and free of lumps. Do not add water arbitrarily or use expired materials, as this will affect the strength and sintering performance.

4. Construction and Shaping

For refractory bricklaying: Staggered joints should be used, with joints controlled within 1-2mm. Refractory mortar should be used to fill the joints if necessary.

For castable refractory: Pour in layers, each layer not exceeding 300mm in thickness. Use a vibrator to compact the refractory material to prevent voids.

For ramming refractory: Compact in layers, paying attention to the compaction at corners. The surface should be smooth and tight after construction.

5. Curing and Furnace Drying

After construction, natural curing or artificial moisture-retaining curing should be carried out.

Curing at room temperature generally takes 24-48 hours.

Before furnace drying, ensure the material reaches the specified strength.

The furnace drying process should involve slow heating to prevent moisture concentration that could cause cracking.

Furnace heating is typically carried out in stages, for example: Holding at 100℃ for several hours to remove free water → Removing crystal water at 300℃ → Stable sintering above 800℃.

III. Precautions for Refractory Material Construction

Strict Material Management

Materials from different manufacturers or batches must not be mixed.

The storage environment must be moisture-proof, rain-proof, and pollution-proof.

Physical properties (such as compressive strength and particle size distribution) must be re-inspected before use.

Construction Temperature and Humidity Control

When the ambient temperature is below 5℃, insulation or heating measures should be taken.

Excessive humidity can lead to abnormal hydration reactions, affecting the density of the refractory layer.

Standardized Vibration and Pouring Process

Excessive vibration can cause delamination and segregation; insufficient vibration can result in porosity.

The pouring process should be continuous, with intervals not exceeding 30 minutes.

Preventing Cracks and Spalling

Drying must be slow before furnace drying;

The furnace body should be heated evenly in the initial stage;

Excessive temperature difference inside the furnace can cause stress cracks; zoned heating is necessary.

Safety Construction Requirements

Ventilation and protective equipment must be available on site;

Operators must wear dust and heat protection equipment;

Overheating or rapid heating is strictly prohibited during furnace drying.

IV. Quality Acceptance and Maintenance Recommendations

After construction, the following items should be checked:

Appearance flatness and density;

Brick joint width and staggered joint overlap;

Whether the surface of the castable is free of pores and cracks;

Whether the thickness of key parts meets the standards.

After commissioning, the furnace lining condition should be checked regularly. Any local spalling or bulging should be repaired promptly to avoid heat loss and structural damage.

V. Conclusion

Refractory material construction is a systematic project that requires both adherence to scientific processes and strict control of every construction detail. Only by ensuring **"qualified materials, standardized processes, adequate curing, and proper furnace drying"** can we guarantee a dense and reliable furnace lining structure, significantly improving the service life and operational efficiency of refractory materials.