Bricks are one of the oldest and most reliable construction materials used across the world. From small houses to massive historical monuments, bricks have stood the test of time because of their strength and durability. But not all bricks are the same. One of the key distinctions in brick manufacturing is between burnt bricks and unburnt bricks. Many people often wonder what exactly is the difference between the two, and which type is best suited for construction. In this detailed guide, we will explore everything about burnt vs unburnt bricks, their properties, advantages, disadvantages, and practical uses so you can make informed choices in construction.
What Are Burnt Bricks?
Burnt bricks are the traditional and most commonly used bricks in construction. They are manufactured by molding clay into rectangular shapes, drying them in the sun, and then burning them in kilns at high temperatures (around 1000°C). The process of burning gives them hardness, durability, and strength, making them suitable for permanent construction. Burnt bricks are classified into four types depending on quality: first-class, second-class, third-class, and fourth-class bricks.
Properties of Burnt Bricks
- Hard and durable
- Uniform reddish or copper color
- Fire resistant and weather resistant
- Higher compressive strength (above 3.5 MPa)
- Less water absorption (15–20%)
Types of Burnt Bricks
- First-class bricks: High strength, uniform shape, suitable for load-bearing walls
- Second-class bricks: Slightly irregular, used in plastered walls
- Third-class bricks: Poor quality, not suitable for permanent structures
- Fourth-class bricks: Over-burnt, used as aggregates in road works
What Are Unburnt Bricks?
Unburnt bricks, also called sun-dried bricks, are the earliest form of bricks used by humans. They are made from clay mixed with water and sometimes straw or husk, molded into shape, and then dried under the sun. They are not burned in kilns, which makes them less strong compared to burnt bricks. These bricks are still used in rural areas and temporary structures because they are cheaper and eco-friendly.
Properties of Unburnt Bricks
- Light in weight
- Low strength compared to burnt bricks
- Absorb more water
- Poor resistance to fire and weather
- Environmentally friendly and energy-efficient production
Burnt vs Unburnt Bricks: Key Differences
To understand clearly, let’s compare the two types of bricks side by side.
| Aspect | Burnt Bricks | Unburnt Bricks |
|---|---|---|
| Manufacturing | Molded and burned in kilns at high temperatures | Molded and dried in sunlight |
| Strength | High compressive strength (3.5 MPa and above) | Low strength, not suitable for heavy loads |
| Durability | Long-lasting, resistant to fire and weather | Less durable, easily damaged by water |
| Color | Uniform red or copper | Dull brown or light color |
| Water Absorption | 15–20% | Higher than 25% |
| Uses | Permanent structures, load-bearing walls, foundations | Temporary huts, rural housing, non-load-bearing walls |
| Cost | More expensive | Cheaper |
| Eco-Friendliness | Consumes fuel during burning | Environmentally friendly, no fuel required |
Advantages of Burnt Bricks
- High durability and long life
- Strong enough for load-bearing structures
- Resistant to fire and harsh weather conditions
- Uniform appearance and size for better aesthetics
- Widely available and trusted in construction
Disadvantages of Burnt Bricks
- More expensive compared to unburnt bricks
- Requires large amounts of fuel for burning, which impacts the environment
- Heavier in weight, leading to more dead load on structures
- Labor and time-intensive manufacturing process
Advantages of Unburnt Bricks
- Very cheap and affordable
- Easy to manufacture with simple tools
- Environmentally friendly as no fuel is required
- Lightweight and easy to handle
- Suitable for temporary and rural construction
Disadvantages of Unburnt Bricks
- Poor strength and not suitable for load-bearing structures
- High water absorption leading to dampness and erosion
- Not fire-resistant, can get damaged in high heat
- Short lifespan compared to burnt bricks
Uses of Burnt Bricks
- Permanent residential and commercial buildings
- Boundary walls and compound walls
- Foundations and basements
- Load-bearing and non-load-bearing walls
- Paving and flooring when used as over-burnt bricks
Uses of Unburnt Bricks
- Temporary huts and sheds
- Rural housing where cost is a major factor
- Partition walls in non-load-bearing structures
- Small storage units or cattle sheds
- Eco-friendly projects where sustainability is prioritized
Choosing Between Burnt and Unburnt Bricks
When deciding whether to use burnt bricks or unburnt bricks, consider the following factors:
- Purpose of construction: For permanent, strong structures, burnt bricks are the only reliable option. For temporary or rural projects, unburnt bricks may be acceptable.
- Budget: Burnt bricks cost more, but they ensure long-term durability. Unburnt bricks are cheaper but may lead to maintenance and repairs.
- Location: In areas with heavy rainfall or extreme climates, burnt bricks are more suitable because of their durability.
- Environmental impact: If sustainability is a priority, unburnt bricks can be used, but only in non-critical structures.
Environmental Impact of Burnt vs Unburnt Bricks
The production of burnt bricks consumes a lot of fuel (coal, wood, or gas), releasing carbon emissions into the environment. On the other hand, unburnt bricks are energy-efficient and eco-friendly, but they cannot replace burnt bricks in strength-demanding projects. Modern alternatives like fly ash bricks, concrete blocks, and AAC blocks are being developed to reduce environmental impact while maintaining strength and durability.
Burnt Bricks in Modern Construction
Despite the rise of modern alternatives, burnt clay bricks remain the most trusted material in construction. Their proven durability, local availability, and strength make them ideal for most projects. They are often used along with reinforced cement concrete (RCC) and steel to build safe, long-lasting structures.
Unburnt Bricks in Modern Context
While unburnt bricks are considered outdated for urban projects, they are still widely used in rural areas due to their affordability. With better technology, stabilized unburnt bricks (using lime or cement) are being developed, which improve their strength and reduce weaknesses. These stabilized bricks are now being promoted in eco-friendly housing projects.
Burnt vs Unburnt Bricks: Which is Better?
In terms of strength, durability, and safety, burnt bricks are clearly better and widely used in all major construction projects. Unburnt bricks, however, have their place in low-cost housing, temporary works, and eco-friendly applications. Choosing between them depends on the balance between budget, purpose, and longevity.
FAQs on Burnt vs Unburnt Bricks
What is the main difference between burnt and unburnt bricks?
Burnt bricks are fired in kilns at high temperatures, making them strong and durable, while unburnt bricks are sun-dried and weaker.
Are unburnt bricks suitable for permanent construction?
No, unburnt bricks are not suitable for permanent structures because they have low strength and poor resistance to water and fire.
Which bricks are more eco-friendly?
Unburnt bricks are more eco-friendly because they do not require burning and fuel consumption, but they lack durability.
Can unburnt bricks be improved for strength?
Yes, by adding stabilizers like lime, cement, or fly ash, unburnt bricks can gain better strength and durability. These are called stabilized soil bricks.
What is the compressive strength of burnt bricks?
First-class burnt bricks have compressive strength above 10 MPa, while common burnt bricks usually have at least 3.5 MPa.
Why are burnt bricks still preferred today?
They are preferred because of their proven strength, durability, fire resistance, and ability to withstand harsh weather, making them ideal for permanent structures.
Are there better alternatives than burnt bricks?
Yes, fly ash bricks, AAC blocks, and concrete blocks are modern alternatives that are strong, lightweight, and more eco-friendly.
