One cannot imagine a construction sector without the use of bricks. People have been using bricks for thousands of years to construct versatile buildings. Their durability and compressive strength make them apt for construction and civil engineering projects. In earlier days, the brick forms used were unburnt and dried naturally using sunlight. This factor reduces their overall strength and is not widely used in modern construction and civil engineering. While we have many types of bricks suitable for various construction plans, this article gives a brief description of red brick. Red bricks are one of the oldest and most traditional construction materials that can be found in practice.
What are Red Bricks?
This type of brick is fired in a kiln or dried in the sun. Like other types, they appear to be rectangular blocks. Their hard and dense strength has made them preferable over other materials for centuries as a structural building material. In many cases, the strength produced by these bricks negates the need for reinforcement supports on roofs and floors. This traditional brick is mainly made of natural clay. They not only provide durability but also offer classic aesthetic appeal.
Types of Red Bricks
While bricks themselves can be divided into various types, the manufacturing method employed in the creation of red bricks classifies them into several kinds. The classification based on the manufacturing of red bricks is,
- Unburnt or Sun-dried Bricks: This type of red brick is formed by exposing the moulded clay to the heat from the sunlight. This natural exposure to the sunlight does not provide the necessary strength to be used in a permanent structure. Their lower durability makes them suitable for temporary structures.
- Burnt Clay Bricks: Unlike sun-dried bricks, burnt clay bricks are made in a kiln inside the factory. In recent times, these bricks have been preferred by many construction projects. While they are good in quality, they have their shortcomings. These burnt clay bricks can be further classified into four different types of red bricks. They are,
- First Class Bricks: These bricks are manufactured from good-quality plastic earth that is free from saline deposits. The moulded clay is burnt in large kilns. They are well-known for their standardised size and colour uniformity. Some unique features of first-class bricks are straight edges and even surfaces, free from cracks, chips, flaws, and lime nodules, less water absorption, and greater strength.
- Second Class Brick: The ground moulded clays are burnt in kilns. While they conform to the standard size of first-class brick, they differ in shape and colour. They are not free from cracks, and their edges are not sharp and uniform as in the case of first-class brick.
- Third Class Bricks: Unlike the above two, this type is not fully burnt. This gives a reddish-yellow colour to the brick. While they have rough surfaces, distorted edges, and less strength, their high-water absorption capability makes this one among several choices of bricks.
- Fourth Class Bricks: This type is notorious for its poor quality. Considering their poor-quality characteristics, they are crushed and used as aggregate after over-burning. This leaves them in a state that is fragile and makes them preferred less often as a main element of buildings.
Properties of Red Bricks
- In terms of material composition, natural clay is moulded and fired at high temperatures, and the presence of iron oxide in the clay turns the clay red.
- The red bricks’ compressive strength ranges between 3.5 to 35 MPa. This makes them suitable for load-bearing. Their durability allows them to withstand harsh weather conditions.
- Thermal insulation provides good maintenance of indoor temperatures. The density of the red bricks resists noise transmission, contributing to acoustic comfort.
- It can absorb about 15-20% of their weight. The non-combustible property makes them ideal for use in fireplaces.
Advantages of Red Bricks
- The prevalence and usage of red bricks lasting through generations speak about the durability and longevity they possess.
- The thermal comfort provided by insulating the house reduces warmth in the summer and coldness in the winter.
- Their aesthetic versatility makes them suitable for both traditional and modern designs.
- Durability reduces the need for replacement very often, decreasing the overall cost in the long run.
- As they are made of natural clay, they can be recycled, a step towards eco-friendliness.
Disadvantages of Red Bricks
- In comparison to concrete blocks or lightweight blocks, their heavy weight poses challenges for the contractor in transporting and handling the bricks.
- Even though water absorption is a positive sign, there is always a likelihood of efflorescence which occurs when white salt will deposit if not treated properly.
- The labour-intensive work causes time consumption, increasing the possibility of delays in project completion.
- Temperature fluctuations may cause cracking in some instances.
Manufacturing Process of Red Bricks
- As the first step, the natural clay is extracted. Impurities attached to the raw clay are cleaned. Crushing and grinding are necessary to attain a fine texture. To achieve the desired moulding, water is added to the clay.
- Either hand moulding or machine moulding can be used to give the clay a constant size and shape to the bricks. In some cases, wires are used to cut them in uniform shapes.
- Prepared bricks are dried in controlled chambers to expedite the process. This helps in reducing moisture content and preventing cracks.
- The dried bricks are then heated in a kiln. They undergo a series of procedures such as water smoking, dehydration, and vitrification.
- Following all these steps, the prepared brick is cooled slowly to room temperature and the bricks are sorted and packed for transport and storage.
Conclusion
Red bricks have been, and continue to be, a common construction material, which is quite durable, beautiful and environmentally friendly. Although it is the inherent raw material and the way these are produced that makes them unique, there are drawbacks such as their weight and the risks of efflorescence. Knowing their merits and demerits, builders can incorporate them in specific construction works in a prudent manner that integrates the traditional aesthetics with the modern construction technology.