When it comes to bricks, not all of them are created equal. You’ve got your top-tier, shiny red bricks that are picture-perfect—and then there are the rugged, irregular, and somewhat misunderstood ones: fourth-class bricks. While they might not be winning any beauty contests, they sure do have their place in construction.
In this guide, we will break down everything you need to know about fourth-class bricks—how they’re made, what makes them unique, where they shine, and where they fall short.
What Are Fourth Class Bricks?
The Basics of Brick Classification
Bricks are usually categorized based on quality, finish, and strength. In India and many other countries, they’re divided into four classes:
- First Class: High quality, well-burnt, uniform shape.
- Second Class: Slightly irregular but still decent quality.
- Third Class: Poor finish, low strength, used in temporary works.
- Fourth Class: Overburnt, misshapen, and often broken.
Where Do Fourth Class Bricks Stand?
Fourth-class bricks are the leftovers, the by-products of over-firing or improper handling during the brick-making process. They’re typically distorted, brittle, and not fit for walls or load-bearing structures. But don’t write them off just yet—they’ve got some surprisingly useful applications.
How Are Fourth Class Bricks Made?
Manufacturing Process
Fourth-class bricks aren’t made intentionally—they’re the result of manufacturing flaws. During firing, bricks that are placed too close to the fire or exposed to uneven temperatures get overburnt. This leads to partial melting or excessive hardness, making them structurally unsound for standard masonry.
Common Causes of Imperfection
- Improper stacking in kilns
- Uneven heat distribution
- Using poor-quality clay
- Lack of moisture control
- Overfiring due to negligence or rushed production
Properties of Fourth Class Bricks
Physical Properties
Size and Shape
Unlike the sharp-edged, uniform bricks you’d use for building walls, fourth-class bricks are irregular in shape and often cracked or broken.
Texture and Appearance
They usually appear dark red or even black due to overburning. The surface is rough and sometimes partially vitrified.
Weight and Density
These bricks are usually heavier and denser because of the excessive firing. However, some may also be brittle and easy to crush.
Mechanical Properties
Strength and Durability
Not strong at all. They have poor compressive strength and break easily under pressure. Definitely not the type you want holding up your house.
Water Absorption Capacity
They can absorb a high amount of water, which makes them unsuitable for water-prone structures.
Fire Resistance
Ironically, due to overburning, they are somewhat fire-resistant. But this doesn’t compensate for their structural weaknesses.
Chemical Properties
Composition
They’re made of the same clay as regular bricks but have undergone chemical changes due to high temperatures. This changes their mineral structure.
Reaction to Environmental Conditions
They don’t fare well in freezing and thawing cycles and tend to crumble over time if exposed to weather.
Uses of Fourth Class Bricks
In Construction
For Foundation Filling
Believe it or not, fourth-class bricks are great for filling foundation trenches. They offer a cheap and effective filler before pouring concrete.
In Temporary Structures
Since they’re not meant to last forever, they’re often used in temporary sheds, storage areas, or boundary walls.
As Aggregates
In Concrete
Crushed fourth-class bricks work wonderfully as coarse aggregates in concrete for non-structural work.
In Road Construction
They are used under road pavements to create a base or sub-base layer, giving a decent compact foundation.
In Landscaping
Garden Paths and Pavements
Crushed bricks can be used in garden paths to give that rustic, earthy look.
Sub-base for Pavers
They act as an excellent sub-base material under interlocking pavers or tiles, especially in walkways or patios.
Limitations of Fourth Class Bricks
Structural Weakness
They’re too weak for walls, columns, or any load-bearing element.
Inconsistency in Quality
Every batch looks different. Some are strong, others crumble in your hand. This makes planning difficult.
Not Suitable for Load-Bearing Walls
Building a wall with these is like using sponge blocks—don’t even think about it.
Poor Aesthetic Appeal
Let’s face it: they’re not pretty. You wouldn’t want them anywhere visible in your home or office.
Low Resistance to Weathering
Rain, frost, and sun will wear them down faster than you can say “maintenance.”
Tips for Using Fourth-Class Bricks Effectively
How to Identify Fourth-Class Bricks on Site?
Look for:
- Irregular shapes
- Cracked or broken edges
- Dark or black colour
- Excessive weight
- Brittle nature
When and Where to Use Them
Use them when:
- Aesthetics don’t matter
- You need filler material
- You’re constructing a temporary structure
- Landscaping or garden designs need a rustic look
Mixing with Cement or Concrete
Crush them and mix them with cement or sand to form a granular base layer. They can add bulk to the mix without much cost.
FAQs
What is the difference between first-class and fourth-class bricks?
First-class bricks are strong, uniform, and suitable for load-bearing structures, while fourth-class bricks are overburnt, irregular, and mostly used as filler or aggregates.
Can fourth-class bricks be reused?
Yes, they can be crushed and reused as aggregates in non-structural concrete or road base layers.
Are fourth-class bricks safe for home construction?
Not for walls or main structures, but they’re safe to use in foundations or as fillers.
How do I identify fourth-class bricks on-site?
Look for overburnt, misshapen, broken, or black-coloured bricks with brittle texture.
What are some eco-friendly ways to use broken bricks?
Use them in landscaping, garden paths, drainage layers, or as recycled aggregates in concrete mixes.