Calcium Silicate Insulation Brick — Hard Silica-Calcium Composite Series
Mingfa's pressed calcium silicate brick series combines thermal insulation with structural load-bearing capacity. Four product families — MFBL, MFDJ, MFGB, and HCS — span density from 300 to 900 kg/m³ with compressive strength from 3 to 15 MPa. For furnace backup linings, kiln car decks, and structural thermal barriers rated to 1000-1100°C.
1. Calcium Silicate Insulation Brick Overview
Mingfa's calcium silicate insulation brick is a pressed hard silica-calcium composite designed for applications where the insulation layer must carry structural load. Unlike calcium silicate board, which is optimized for thermal resistance on large flat surfaces, brick products are engineered for compressive strength, curved-surface installation, and brickwork pattern compatibility with the refractory working lining.
Material Basis
All brick products share the same xonotlite (6CaO·6SiO&sub2;·H&sub2;O) crystal chemistry as Mingfa's board products. The key difference is density: while standard board ranges from 170-270 kg/m³, insulation brick is pressed to densities from 300 to 900 kg/m³. This higher density trades some thermal resistance for significantly higher compressive strength, making the brick suitable for load-bearing applications where standard board would crush.
Temperature Capability
Standard series (MFBL, MFDJ, MFGB) are rated for continuous service at 1000°C. The HCS (Hard Silica-Calcium Composite) series is rated to 1100°C, matching the temperature capability of the LG-High Temp board. This makes HCS bricks suitable for the hottest furnace zones where standard calcium silicate brick would approach its temperature limit.
2. Product Specifications
Technical specifications for all four calcium silicate brick product series. Select based on the balance of compressive strength, thermal conductivity, and chemical resistance required by your application.
| Series | Density (kg/m³) | Compressive Strength (MPa) | Flexural Strength (MPa) | Thermal Cond. @ 400°C (W/m·K) | Max Temp (°C) | Primary Application |
|---|---|---|---|---|---|---|
| MFBL-30Q | 300 | ≥3.0 | ≥1.0 | ≤0.08 | 1000 | Glass furnace crown backup (low load) |
| MFBL-50 | 500 | ≥5.0 | ≥1.5 | ≤0.10 | 1000 | Sidewall backup, general furnace backup |
| MFBL-60 | 600 | ≥6.0 | ≥2.0 | ≤0.12 | 1000 | General backup, bottom paving support |
| MFBL-85 | 850 | ≥10.0 | ≥3.5 | ≤0.20 | 1000 | Bottom paving support (high load) |
| MFDJ-30 | 300 | ≥3.0 | ≥1.0 | ≤0.08 | 1000 | Aluminum reduction cell insulation |
| MFDJ-40 | 400 | ≥5.0 | ≥1.5 | ≤0.10 | 1000 | Aluminum cell bottom insulation |
| MFGB-70 | 700 | ≥10.0 | ≥3.0 | ≤0.18 | 1000 | Steel ladle safety lining |
| MFGB-90 | 900 | ≥15.0 | ≥5.0 | ≤0.25 | 1000 | Steel ladle permanent lining (high-load) |
| HCS-40 | 400 | ≥5.0 | ≥1.5 | ≤0.10 | 1100 | Carbon baking furnace, cement kiln hood |
| HCS-60 | 600 | ≥10.0 | ≥3.0 | ≤0.16 | 1100 | Cement kiln hood, high-temp zones |
Standard brick dimensions: 230 × 114 × 65 mm (refractory industry standard, equivalent to 9 × 4.5 × 2.5 inches). Also available in 230 × 150 × 75 mm. Dimensional tolerance: ±1.5mm on length and width, ±1.0mm on thickness. Linear shrinkage at rated temperature is ≤1.5% for all grades per ASTM C356.
3. Comparison with Traditional Firebrick
How calcium silicate insulation brick compares to conventional insulating fire brick (IFB) — understanding the trade-offs helps you select the right material for each furnace zone.
| Property | Calcium Silicate Brick (MFBL 500) | Insulating Fire Brick (IFB Group 23) | Advantage |
|---|---|---|---|
| Density (kg/m³) | 500 | 600-800 | Calcium silicate: lighter weight per unit |
| Thermal Cond. @ 400°C (W/m·K) | ~0.13 | ~0.30-0.40 | Calcium silicate: ~60% lower conductivity |
| Compressive Strength (MPa) | ~8 | 2-5 | Calcium silicate: higher strength at lower density |
| Max Service Temp (°C) | 1000 | 1260 | IFB: higher temperature rating |
| Weight at equal thermal resistance | ~42 kg/m² (65mm) | ~108 kg/m² (135mm) | Calcium silicate: ~60% lighter at equal R-value |
| Ease of cutting | Very easy (carbide tools) | Moderate (diamond tools) | Calcium silicate: faster, less dust |
| Thermal shock resistance | Good | Moderate | Calcium silicate: better cycling tolerance |
| Cost per m³ (relative) | Medium | Medium-High | Calcium silicate: typically lower cost |
When IFB wins: Where the insulation hot-face temperature exceeds 1100°C, typically only when the working lining is very thin, absent, or worn away. When calcium silicate brick wins: For backup insulation behind a dense refractory working lining, where the insulation hot-face stays below 1000°C. Here, calcium silicate provides better thermal resistance at lower weight and cost. The two materials are complementary rather than competing — many furnace lining designs use both, with calcium silicate brick as the cooler backup layer and IFB as the hotter intermediate layer.
4. Applications: Kiln Car Deck, Furnace Backup & Tunnel Kiln
The three primary application categories for refractory insulation brick made from calcium silicate.
Kiln Car Deck
In tunnel kilns for brick, tile, sanitaryware, and technical ceramics, the kiln car deck carries the product load through heating and cooling cycles. Insulation brick forms the deck's thermal barrier layer, reducing heat storage in the car structure — critical for intermittent kilns where the car is heated and cooled each cycle. Lower heat storage means faster cycle times and lower energy consumption. HCS-60 at 1100°C rating is recommended for the upper deck layer.
Furnace Backup Lining
Behind the dense refractory working lining in glass furnaces, steel ladles, aluminum reduction cells, and cement kilns. The calcium silicate brick backup layer provides thermal insulation while supporting the weight of the refractory above it. Grade selection depends on compressive load: MFBL for moderate loads, MFGB for high-load steel ladle applications, MFDJ for aluminum cell environments, and HCS for the highest-temperature zones.
Tunnel Kiln Insulation
Tunnel kiln walls and roof insulation where the kiln structure operates continuously at 1000-1200°C internal temperature. Calcium silicate insulation brick installed behind the hot-face refractory reduces heat loss through the kiln structure, improving thermal efficiency and reducing fuel consumption. The brick format integrates with the masonry construction, and the low thermal conductivity means a thinner backup layer achieves the same insulation value as thicker IFB.
5. Installation: Dry Lay & Mortar Joint Methods
Two installation methods are used for calcium silicate brick, chosen based on the structural requirements of the lining.
Dry Lay Method
When to use: When the brick course is contained within a steel shell that provides structural constraint, such as steel ladle safety linings and furnace shells with retaining plates. Bricks are laid without mortar — the steel shell holds them in place.
Advantages: Faster installation (no mortar mixing or curing time), allows free thermal expansion at each brick-to-brick interface, simplifies brick replacement during maintenance. Expansion allowance is inherent because each joint can close slightly as bricks expand.
Best practice: Stagger vertical joints between courses (running bond pattern). Leave 1-2mm gaps between bricks in each course to accommodate thermal expansion. Ensure the steel shell or retaining plate applies uniform compression to prevent brick movement.
Mortar Joint Method
When to use: When the brick course is free-standing or must be structurally bonded, such as tall vertical walls, arches, domes, and areas where the steel shell does not provide full constraint. A high-temperature inorganic mortar (silicate-based, rated for the brick's service temperature) bonds the bricks.
Advantages: Creates a structurally integrated brickwork that can span openings, form arches, and support its own weight without external constraint. Mortar joints prevent gas bypass through the insulation layer.
Best practice: Mortar joints 1-2mm thick, fully filled. Allow 1mm of expansion gap per linear meter of brickwork at the perimeter and at intermediate intervals for walls longer than 3 meters. Fill expansion joints with ceramic fiber blanket or paper.
6. Custom Sizes & Shapes Available
Beyond standard 230 × 114 × 65 mm bricks, Mingfa produces custom dimensions and shapes to match specific furnace designs.
Custom Dimensions
Non-standard brick sizes are produced with custom press molds. Mold setup time: 2-3 weeks. Typical minimum order quantity for custom dimensions: 5,000 bricks, depending on mold complexity. Available custom formats include larger-format bricks for faster installation, thinner bricks for space-constrained applications, and dimension combinations matched to specific furnace construction drawings.
Custom Shapes
Tapered bricks for curved walls (inner and outer face dimensions differ), radial bricks for domes and arches, and shaped bricks for furnace details such as burner quarls, flue openings, and thermocouple penetrations. Shapes are pressed to drawing in custom molds. Minimum order quantities vary by complexity; contact Mingfa with your drawings for a feasibility assessment and quotation.
7. Ordering Information
Practical details for ordering calcium silicate insulation brick from Mingfa.
Stock Availability & MOQ
- Standard sizes from stock: 230×114×65mm bricks in MFBL, MFDJ, and MFGB series maintained in stock for orders up to 10,000 bricks without production scheduling.
- Larger quantities: Standard lead time 15-25 working days.
- Custom dimensions: MOQ typically 5,000 bricks; custom shapes quoted per project.
- Sample bricks: Available at no charge; customer arranges freight.
Packaging & Shipping
- Pallet packing: ISPM 15 fumigated wooden pallets with corner protection and waterproof PE film wrap. Steel or PET strapping. 500-700 bricks per pallet depending on size.
- Container loading: 20-foot container: 10-12 pallets (5,000-8,400 bricks). 40-foot container: 22-24 pallets (11,000-16,800 bricks).
- Combined shipments: Board and brick products can ship together in a single container package for furnace rebuild projects.
- Documentation: Batch Certificate of Analysis, packing list, commercial invoice included with every shipment.