Autoclaved Fly Ash and Sand-Lime Brick Production Line
Large-scale brick lines that press fly ash or sand with lime into bricks and cure them in autoclaves — high-strength bricks that put industrial by-products to use.
Autoclaved Fly Ash and Sand-Lime Brick Lines We Supply
Autoclaved Brick Production Process
Raw material storage and batching → lime slaking → mixing → pressing → setting onto autoclave cars → autoclave curing → unloading and packing.
Bricks pressed from fly ash or sand with lime are cured in autoclaves under high-pressure saturated steam. The reaction between lime and silica under these conditions gives the bricks their strength — high and consistent, without firing. Sand-lime bricks are also known as calcium silicate bricks.
Raw Materials: Fly Ash or Sand-Lime Bricks
A fly ash brick plant uses large volumes of fly ash from coal-fired power plants, turning a disposal problem into a raw material. Where fly ash is not available, sand-lime bricks use silica sand instead.
| Brick | Typical mix |
|---|---|
| Sand-lime bricks | Lime 8–12%, the rest sand (about 11 : 89 lime to sand) |
| Fly ash bricks | Fly ash 60–70%, lime 8–12%, gypsum 2–3%, and sand or slag aggregate 20–30% |
Fly ash varies from one power plant to the next, and sand and lime vary by source. A raw material test decides the mix and the curing schedule before the line is configured.
Brick Press, Autoclaves and Line Equipment
| Equipment | Typical configuration |
|---|---|
| Brick press | Double-sided hydraulic presses in the 500–800-tonne class; bricks pressed from both sides in two stages at 20–25 MPa; 26 standard bricks per cycle in 18–22 seconds. A 30-million-brick line runs one or two presses. |
| Autoclaves | φ2 × 21 m as standard: two on a 30-million-brick line, three or four on a 60-million-brick line |
| Curing cycle | About 1.4 MPa and 195 °C, about 7 hours per cycle |
| Steam boiler | 2–4 t/h, with steam distribution to the autoclaves |
| Other equipment | Raw material silos, feeders and batching; lime slaking (digester); mixer; autoclave cars and transfer system; unloading and packing |
Brick Types, Strength and Standards
| Standard solid brick | 240 × 115 × 53 mm |
| Multi-hole brick | 240 × 115 × 90 mm — a mould change switches the product |
| Strength classes | MU10–MU25 per GB 11945; MU15 and above for foundations and load-bearing walls |
- ASTM C73 (US) covers calcium silicate (sand-lime) brick in two grades: SW, for exposure to freezing in the presence of moisture, and MW, for freezing but unlikely saturation.
- EN 771-2 (Europe) specifies calcium silicate masonry units for inner and outer walls, cellars and foundations.
- IS 12894 (India) specifies pulverized fuel ash-lime bricks — fly ash bricks — for masonry.
Tell us the brick sizes and the standard your market uses: the press moulds and the curing schedule are set for them.
Capacity, Site and Project Timeline
| Output | 30–120 million bricks a year |
| Site | About 1.0–1.3 ha for a 30-million-brick line; 2.7–4 ha for 100 million bricks a year |
| Delivery | About 2–3 months |
| Installation and commissioning | Usually 3–4 engineers on site for about 3 months, including an experienced autoclave and steam specialist |
These are typical figures; your output, products and site decide the final configuration and schedule. Autoclaved bricks use the same autoclave technology as our AAC block production line.
Which Brick Line Fits Your Project?
| Concrete block / non-fired brick | Autoclaved brick | Fired clay brick | |
|---|---|---|---|
| Raw materials | Cement, sand, crushed stone, fly ash, slag | Fly ash or sand with lime | Clay, shale, coal gangue, fly ash |
| Forming | Vibration and hydraulic pressing | High-pressure pressing | Vacuum extrusion |
| Curing / firing | Curing chambers, no steam | Autoclave (high-pressure steam) | Tunnel kiln |
| Investment | Lowest; quick start | Medium to large | Largest; kiln built on site |
| Typical buyer | County-level — local producers and small building-materials businesses supplying housing in their area | Government-backed — projects that consume fly ash and other industrial solid waste, often next to power plants or in circular-economy parks | Commercial-scale — large building-materials groups supplying urban housing |
| Best for | A first plant for the local market, 30–60 million bricks a year | Large-scale use of fly ash or sand, 30–120 million bricks a year | Large clay-based plants, 60–100 million bricks a year |
| See the concrete block / non-fired brick line → | This page | See the fired clay brick line → |
What to Send for a Quotation
- Target output (bricks a year)
- Brick types and sizes, and the standard your market uses
- Raw materials available: fly ash (with the power plant source), sand, lime — with analyses
- Fuel available for the steam boiler
- Power supply and site dimensions
- Destination country and target timeline
With your output target, destination country and timeline we can start, and you receive a written sourcing report within 48 hours of a complete requirement brief. For other plants, see our building material production lines.
One Partner from Requirement to Running Line
- Requirement review — capacity targets, site conditions and budget
- Equipment selection and supplier matching — vetted Chinese manufacturers
- Plant layout planning — civil works drawings issued early
- Quality inspection and factory acceptance testing before shipment
- Export documentation and freight coordination
- Installation, commissioning and operator training
Frequently Asked Questions
Fly ash or sand?
Both work. Fly ash bricks suit sites near coal-fired power plants; sand-lime bricks use silica sand where fly ash is not available. Send us samples and we will test them.
Why autoclave curing?
Curing under high-pressure steam lets lime react with the silica in fly ash or sand, giving high, consistent strength without firing.
What utilities does the plant need?
A steam boiler for the autoclaves, plus power and water. We size the boiler and autoclaves to your output.
What strength can the bricks reach?
MU10 to MU25 per GB 11945. MU15 and above can be used for foundations and load-bearing walls.
How many presses and autoclaves does a line need?
A 30-million-brick line uses one or two 500–800-tonne double-sided hydraulic presses and two φ2 × 21 m autoclaves; a 60-million-brick line uses three or four autoclaves.
How long does a project take, and who do you send?
Delivery takes about 2–3 months. We usually send 3–4 engineers, including an experienced autoclave and steam specialist, for about 3 months on site.
Should I choose a block line, an autoclaved brick line or a fired clay brick line?
It depends on your raw materials, market and budget. See the comparison above, or send us your project details for a recommendation.
What do you need to prepare a quotation?
Your target output, brick types and sizes, raw materials available (fly ash, sand, lime), fuel for the boiler, project location and planned timeline.
Request an Autoclaved Brick Line Proposal
Tell us your target output, raw materials and brick types. We respond within one business day.
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