What are Bricks Made Of? All Types of Brick Making Process

How Many Types Of Bricks Can Be Made?

Clay Bricks

You'll find that clay bricks are one of the most traditional and common varieties, manufactured by baking-shaped clay in a kiln. The brick is known for its classic appearance and has been a fundamental material for construction through the ages.

Concrete Bricks

Concrete bricks are formed by combining cement and fine aggregates, and unlike clay bricks, they do not require firing. These bricks are valued for their versatility and uniformity, making them a reliable choice for a range of building projects.

Sand Lime Bricks

Composed primarily of sand and lime, sand lime bricks undergo a chemical process brought on by high-pressure steam curing. They are known for their smooth texture and offer a more uniform finish compared to traditional bricks.

Fire Bricks

These bricks are specifically designed to tolerate extreme heat, making them essential for use in furnaces, fireplaces, and other high-heat environments.

Fly Ash Bricks:

Fly ash (a byproduct of coal combustion), combined with water and a binder.

Different Bricks Require Different Materials, Different Raw Material Ratios

The variety of bricks on the market is vast, each with unique compositions tailored to their intended use. Understanding the main ingredients and their ratios is crucial for choosing the right type of brick for your project.

The Ratio for Clay Bricks

Clay bricks are primarily made from clay and shale, materials rich in silicates. Proportions may vary, but a typical ratio is about four parts clay to one part shale. This ensures sufficient plasticity for molding and durability post-firing.

The Ratio for Concrete Bricks

Concrete bricks comprise Portland cement, sand, aggregate (gravel), and water. Ratios can differ, but a common solid-strength blend includes a 1:6 mixture of cement and aggregate combined with an appropriate amount of water to create a dense, structurally sound brick.

The Ration for Sand Lime Bricks

Sand lime bricks are produced using sand, lime, and water. The composition is typically about 90% sand and 10% lime, creating a smoother finish than clay bricks, with excellent compressive strength when cured.

The Ratio for Fire Bricks

For fire bricks, which must withstand high temperatures, the materials include refractory clay, alumina, and silica. A standard mixture might contain 50-75% alumina and 20-25% silica to ensure they maintain structural integrity at temperatures up to 1,700 degrees Celsius.

The Ratio for Fly Ash Bricks

Fly ash bricks, made from about 50-60% fly ash, 8-12% cement, and 30-40% sand or stone dust, are an eco-friendly choice in construction. Fly ash, a coal combustion byproduct, forms the bulk, while cement acts as a binder and sand or stone dust adds strength. This mix ensures durability and sustainability, making these bricks increasingly popular.

Different Bricks, Different Manufacturing Processes

Due to the different requirements for raw materials and their varying proportions, the same equipment cannot be used to manufacture all types of bricks. Different equipment is needed based on the specific production processes.

Clay Brick Making

https://www.youtube.com/watch?v=hT0M046Z2eA&embed=true

When you look into creating bricks, it's pivotal to know that various production methods demand specific types of equipment to achieve the desired quality and efficiency.

The extrusion method, which produces the majority of bricks, utilizes machinery that thoroughly mixes clay or shale with water before forcing the mixture through a die to form a long, continuous column, which is then wire-cut into individual bricks.
https://www.youtube.com/watch?v=VOyOD-6S2jc&embed=true

For the soft mud process, where a relatively moist clay mix is used, bricks are shaped using molds, adding a distinct textured effect. Equipment for this method is often simpler, and typically includes a molding machine that packs the mud into the molds.

The dry press process, often reserved for specialized or refractory bricks, involves machines that use high pressure to form bricks from a mix with minimal water content. The resulting bricks have a smoother finish and more precise edges than those from the previous methods.

Here's a succinct overview of the primary equipment by process:

• Extrusion:
  • Pug mill for mixing
  • Extrusion machine with die
  • Wire cutter
• Soft Mud:
  • Mixer
  • Molding machine
  • Molds with textures (optional)
• Dry Press:
  • Dry clay preparation equipment
  • Hydraulic press

Each technique may also involve secondary equipment, such as conveyors to move the cut bricks to drying areas, or kilns for firing. Your choice must align with the specific process and scale of your brick-making operation.

Concrete Brick Making

https://www.youtube.com/watch?v=vyazTccu0WQ&embed=true

Concrete bricks are a blend of cement, sand, water, and possible aggregates. The process involves mixing these materials and pouring them into molds where they are allowed to set. Unlike clay bricks, concrete bricks cure through a chemical reaction called hydration, which can take place at ambient temperatures.

Process of Concrete Brick Making:

1. Batching: Accurate measurement of cement, sand, aggregates, and water.
2. Mixing: These materials are mixed together in a concrete mixer to form a homogenous concrete mix.
3. Molding: The concrete mix is then transferred to a brick-making machine where it's molded into bricks.
4. Curing: The formed bricks are left to cure, gaining strength and hardness.
5. Quality Check and Storage: Final quality checks are performed before the bricks are stored and ready for use. 

Concrete Brick Making Machine: This is the main machine used for molding the concrete mix into bricks. It can be manual, semi-automatic, or fully automatic, depending on your budget and production needs. Options include stationary machines or mobile brick-making machines.

Sand Lime Brick Making

https://www.youtube.com/watch?v=YdMrW_wFZq8&embed=true

Sand lime bricks, as the name suggests, are manufactured from a mix of sand, lime, and water. The components undergo a chemical reaction during a high-pressure steam curing process called autoclaving. This process results in a brick with a smooth finish and a uniform shape, often used when a precise and aesthetic look is necessary.

Process of Sand Lime Brick Making:

1. Batching and Mixing: Sand, lime, and water are accurately measured and mixed. The sand is usually finely ground to ensure homogeneity, and the lime acts as the binding agent.
2. Molding: The mixture is then molded into the desired shape. This is typically done using a high-pressure brick press.
3. Autoclaving: The formed bricks are subjected to high-pressure steam curing in an autoclave. This process chemically reacts the lime with silica in the sand, resulting in strong, hardened bricks.
4. Quality Check and Storage: After autoclaving, bricks are tested for quality such as brick size standards , strength, and durability before being stored and dispatched.

The Main Machines:

1. High-Pressure Brick Press Machine: For molding the mixture into brick shapes under high hydraulic pressure.
2. Autoclave: A large, steam-heated vessel where the chemical reaction takes place, and bricks are hardened.

Fire Brick Making

Fire bricks, also known as refractory bricks, are specially made to withstand high heat. The essential ingredients include fireclay and alumina, which give the bricks their heat-resistant properties. After shaping, fire bricks are fired in a kiln at even higher temperatures than clay bricks, making them suitable for lining furnaces and kilns.

Process of Fire Brick Making:

1. Batching: Refractory clays, high alumina minerals, and other additives are measured and combined.
2. Mixing: The materials are mixed with water to form a pliable clay body.
3. Molding: The clay mixture is then molded into the desired shape, either through extrusion, pressing, or casting.
4. Drying: The formed bricks are air-dried to remove as much moisture as possible before firing.
5. Firing: The dried bricks are fired at very high temperatures in a kiln to vitrify the clay and form a strong, dense structure.
6. Sorting and Inspection: After cooling, bricks are inspected for quality and sorted based on size and shape.

The Main Machines:

1. Brick Forming Press Machines: For shaping the bricks.
2. Dryers: To remove moisture before firing.
3. Kiln: A high-temperature furnace for firing the bricks.

Fly Ash Brick Making

https://www.youtube.com/watch?v=CdlwCwL8JBo&embed=true

Fly ash brick making is the process of producing bricks using fly ash, which is a byproduct from burning pulverized coal in electric power generating plants. This method is an eco-friendly alternative to traditional brick manufacturing, which uses natural clay. The key steps in fly ash brick making are:

1. Raw Material Preparation: Fly ash is mixed with water, cement, and sand or stone dust. The proportions vary, but a common mix includes 50-60% fly ash, 10-12% cement, and 30-40% sand or stone dust.
2. Mixing: The ingredients are thoroughly mixed to form a uniform compound. The mixing process ensures that cement evenly binds the fly ash and sand or stone dust.
3. Molding: The mixed material is then fed into a brick molding machine. Depending on the machine, this can be done manually or automatically. The machine compresses the mixture into the shape of a brick.
4. Drying and Curing: The formed bricks are then dried to remove excess moisture. This can be done naturally under the sun or in drying chambers. After drying, the bricks undergo curing, which is a hydration process to achieve the desired strength. This is often done by keeping the bricks in a moist environment for a certain period.
5. Quality Checking and Storage: Once cured, the bricks are checked for quality in terms of size, shape, and strength. Substandard bricks are removed. The rest are stacked and stored, ready for use in construction.

Fly ash brick making is lauded for its low environmental impact, as it recycles industrial waste, requires less energy than traditional clay brick making, and reduces the excavation of topsoil for brick production. The end products are durable, have good thermal insulation properties, and are often more cost-effective.

If you found this information engaging, consider checking out our other articles that delve into Concrete Block vs. Cement Block vs. Cinder Block and How to Choose the Right Paver for Your Project.