Building Material and Construction: Bricks
Contents
Recall the composition of Brick Earth 2
Recall different Defects in Bricks: i. Chuffs, ii. Bloating, iii. Cracks, iv. Blistering 12
Define the term Brick
The term “brick” refers to a rectangular building block made from fired clay or other ceramic material, such as concrete or glass. Bricks are used in a wide range of construction projects, from houses and apartment buildings to commercial and industrial structures.
Bricks have been used for construction for thousands of years, with some of the earliest examples dating back to ancient civilizations in Mesopotamia and Egypt. The process of making bricks has evolved over time, but the basic principles remain the same. Clay or other raw materials are mined or sourced, then ground and mixed with water to form a cohesive mixture. This mixture is then shaped into bricks and fired at high temperatures to harden and strengthen the material.
Bricks are an enduring and versatile building material, and are used in a wide range of construction methods. Some of the most common ways that bricks are used in construction include:
- Load-bearing construction: In this method, bricks are used to support the weight of the structure above. This is the most common use of bricks in traditional construction methods.
- Veneer construction: In this method, bricks are used as a decorative facade over a structural frame made of wood or steel.
- Infill construction: In this method, bricks are used to fill in the gaps between a structural frame, providing insulation and additional structural support.
Bricks come in a wide range of sizes, shapes and colors, and can be used in a variety of creative ways to add visual interest to a structure. Moreover, Brick is also a good insulator, and helps to keep buildings warm in the winter and cool in the summer.
One of the main advantages of bricks as a building material is that they are extremely durable and long-lasting. Bricks are resistant to fire, pests, and weathering, and can last for many decades with proper care and maintenance. They are also relatively low-maintenance and do not require regular painting or staining like other building materials.
On the other hand, the main disadvantage is the weight of the bricks, which require a well-designed foundation to be supported, and that can make the construction process more complex and costlier. Additionally, bricks can be relatively heavy and difficult to work with, which can be a limitation for certain types of construction projects.
In summary, “Brick” refers to a rectangular building block made from fired clay or other ceramic material that is commonly used as a building material in construction projects due to its durability, low maintenance, and ability to withstand different environmental factors like fire and weathering.
Recall the composition of Brick Earth
i. Alumina
* It is the main principal constituent of every kind of brick. It acts as a cementing material in raw brick.
* It gives plasticity to the earth and makes the brick hard.
* Good brick contains about 30% of alumina.
* Excess alumina may result in the shrink, warp, or crack in the brick on burning or drying.
ii. Silica
* Silica imparts hardness to the brick.
* Addition of silica also increases durability and resistance to heat.
* Good brick contains about 55% of silica.
* Excessive silica may lead to brittle or weak bricks.
iii. Lime
* When lime is present in small quantities in freely divided states, it reduces the shrinkage of bricks, helps silica melt at a lower temperature, and binds the particles of the brick together, resulting in greater strength of the brick.
* Excess lime causes the brick to melt and lose shape.
* Good brick contains about 1% of lime.
iv. Iron Oxide
* Iron Oxide imparts a red colour to the bricks.
* Good brick contains about 8% of Iron oxide.
* It helps silica to fuse at a low temperature.
v. Magnesia
* A small proportion of magnesium decreases shrinkage and gives a yellow tint to the bricks.
* An excess amount of magnesia causes bricks to decay.
* Good brick contains about 5% of magnesia.
Recall the manufacturing procedure of the clay bricks: i. Preparation of clay, ii. Moulding iii. Drying iv. Burning
The manufacturing procedure for clay bricks involves several steps, including the preparation of clay, moulding, drying, and burning. These steps are essential to ensuring that the bricks are strong, durable, and suitable for use in construction.
- Preparation of clay: The first step in the manufacturing process is to prepare the clay. This typically involves sourcing raw clay from a clay pit or quarry. The clay is then transported to the brick factory where it is ground, crushed, and mixed with water to form a cohesive mixture. The mixture is then screened to remove any impurities or foreign materials, and may be blended with other materials to improve the quality of the bricks.
- Moulding: After the clay mixture is prepared, it is ready to be moulded into bricks. Bricks are typically formed using a machine called a brick press or extruder, which compacts the clay mixture into a rectangular shape. The moulded bricks are then removed from the press and placed on pallets or racks to dry.
- Drying: Before the bricks can be fired, they must be dried to remove excess moisture. The drying process can be done in one of two ways: sun-drying or kiln-drying. Sun-drying is the traditional method, where the bricks are left outside to dry naturally under the sun. However, this method can take weeks or even months, depending on the weather conditions. On the other hand, kiln-drying is a faster method in which bricks are dried in a special oven called a kiln, which circulates hot air around the bricks to speed up the drying process. Drying process is critical to the final properties of the brick, as it can affect the porosity, strength and shrinkage of the bricks.
- Burning: After the bricks have been dried, they are ready to be fired or burned. The burning process is typically done in a kiln, which is a large, industrial oven that can reach temperatures of up to 1,400 degrees Celsius (2,550 degrees Fahrenheit). The bricks are placed in the kiln, and the temperature is gradually increased over the course of several days. The high temperatures cause chemical changes to take place in the bricks, which harden and strengthen them. The duration and temperature of firing are critical factors that affect the quality of the bricks.
In summary, the manufacturing process of clay bricks involves several steps, including the preparation of clay, moulding, drying, and burning. Each step is essential to ensuring that the bricks are strong, durable, and suitable for use in construction. The bricks are formed by moulding the clay mixture, dried to remove the excess moisture and finally, the bricks are fired to harden and strengthen the material, resulting in a product that is suitable for use in construction.
Recall the following tests of Brick: i. Dimension test, ii. Compressive strength test, iii. Water absorption test iv. Efflorescence test
Bricks are an important building material and must meet certain standards to ensure that they are suitable for use in construction. To evaluate the quality and suitability of bricks, several tests are conducted to measure their properties and performance. Some of the most common tests of bricks include:
- Dimension test: The dimension test is used to measure the size and shape of a brick. This test is conducted to ensure that the bricks are of uniform size and shape and conform to the standard specifications. The bricks are measured for their length, width, and height to ensure that they meet the specified dimensions.
In India, Bricks are made by burning clay in a kiln. Standard Size of Burnt Clay Brick has been mentioned in IS: 2691:1988 Revision 2 (Clause 4.1 & 4.2) as 190 x 90 x 90 mm or 19 cm x 9 cm x 9 cm. - Compressive strength test: The compressive strength test is used to measure the ability of a brick to resist compressive forces. This test is conducted by placing a brick in a compression testing machine and applying a load until the brick is crushed. The compressive strength of the brick is calculated by dividing the load at failure by the area of the brick. The compressive strength test is an important indicator of the quality of the bricks, as it helps to ensure that the bricks are strong enough to support the weight of the structure.
The minimum crushing strength of common burnt clay brick is 3.5 MPa. - Water absorption test: The water absorption test is used to measure the amount of water a brick can absorb. This test is conducted by immersing a brick in water for a specific period of time and then measuring the weight of the brick before and after immersion. The water absorption rate is then calculated as the percentage of weight increase of the brick. The water absorption test is important as bricks that absorb a lot of water can be more prone to damage and deterioration over time.
Percentage of Water absorption of brick, after 24-hour immersion in cold water is calculated by the following formula
(W2-W1)/W1*100
For first class bricks, should not more than 15 %
For second class bricks, it should not more than 20 %
For third class bricks, it should not more than 25 %
- Efflorescence test: Efflorescence is the presence of a white powdery substance on the surface of the bricks caused by the presence of salts. The efflorescence test is conducted by immersing the brick in water and observing the presence or absence of efflorescence. Efflorescence can be indicative of poor quality bricks that may have been made using substandard raw materials or manufacturing processes.
In summary, bricks must meet certain standards to ensure they are suitable for use in construction. There are several tests that are conducted to measure the properties and performance of bricks, including Dimension test, Compressive strength test, Water absorption test, and Efflorescence test. Dimension test is used to ensure that the bricks are of uniform size and shape, Compressive strength test measures the ability of a brick to resist compressive forces, Water absorption test measures the amount of water a brick can absorb and Efflorescence test measures the presence of a white powdery substance on the surface of the bricks caused by the presence of salts. These tests are important for evaluating the quality and suitability of bricks for construction.
Recall the following types of Brick: i. On the basis of the burning, ii. On the basis of the Compressive strength iii. On the basis of the Physical property, iv. On the basis of special types of Bricks
Recall the following types of Brick:
i. On the basis of the burning:
Bricks can be classified into two categories on the basis of burning:
- Soft mud bricks: These bricks are made from a mixture of clay, water, and sand. They are not fired at high temperatures, so they are relatively soft and weak. They are not suitable for use in load-bearing walls or in areas with high precipitation or freeze-thaw cycles.
- Hard fired bricks: These bricks are made from a mixture of clay and other minerals that are fired at high temperatures (usually around 1,200-1,400 degrees Celsius) in a kiln. They are much harder and stronger than soft mud bricks, and are suitable for use in load-bearing walls and in areas with high precipitation or freeze-thaw cycles.
ii. On the basis of the Compressive strength:
Bricks can be classified on the basis of their compressive strength:
- Class A bricks: These bricks have a compressive strength of more than 75 N/mm²
- Class B bricks: These bricks have a compressive strength between 50 N/mm² and 75 N/mm²
- Class C bricks: These bricks have a compressive strength of less than 50 N/mm²
iii. On the basis of the Physical property:
Bricks can be classified on the basis of their physical properties:
- Water-resistant bricks: These bricks are made from clay that is naturally resistant to water or has been treated to make it water-resistant. They are suitable for use in areas where there is a high risk of water damage.
- Insulating bricks: These bricks have insulating properties, meaning they can reduce heat loss through walls. They are made from lightweight materials such as cellular concrete, perlite or vermiculite.
iv. On the basis of special types of Bricks:
- Pressed bricks: These bricks are made by pressing a mixture of clay and other minerals under high pressure. They are stronger than standard bricks and have a smooth, uniform surface.
- Reinforced bricks: These bricks have steel or other reinforcement materials embedded in them to increase their strength. They are suitable for use in load-bearing walls and in areas prone to natural disasters.
- Face bricks: These bricks are mainly used as a decorative facing material, due to their attractive and smooth finish. They are often made from high-quality clays and fired at high temperatures.
It is worth mentioning that, in some regions and areas, the classification of bricks could vary based on the standard and guideline applied by the particular area. This above explanation is based on general classification
Recall the following Harmful Ingredient in Bricks: i. Sulphur, ii. Pyrite, iii. Pebbles, iv. Alkalis, v. Lumps of Lime
Harmful ingredients in bricks can negatively impact the strength, durability, and overall quality of the brick, and can also cause problems during construction. The following are five harmful ingredients in bricks that it is important to recall:
- Sulphur: Sulphur can be present in bricks as a result of using coal or oil as fuel in the brick-making process. When exposed to moisture and air, sulphur can react and form sulphuric acid, which can cause the bricks to weaken and become brittle. This can lead to cracking and structural failure, making the bricks unsafe to use.
- Pyrite: Pyrite, also known as iron sulphide, is a mineral that can be present in clay used to make bricks. When exposed to moisture and air, pyrite can react and form sulphuric acid, which can cause the same issues as sulphur. Additionally, pyrite can cause staining, discoloration, and efflorescence (white powdery deposit on the surface) on the bricks.
- Pebbles: Pebbles or other large particles in the clay used to make bricks can create weak spots in the brick and make it more susceptible to cracking and breaking. Additionally, pebbles can cause problems during construction, as they can make the brick more difficult to lay and can lead to uneven surfaces.
- Alkalis: Alkalis, such as sodium and potassium, can be present in bricks as a result of using certain types of clay or by adding chemicals during the brick-making process. Alkalis can react with certain types of minerals in the brick, such as alumina and silica, causing the brick to expand and crack. This can cause structural issues and make the brick unsafe to use.
- Lumps of Lime: Lime is a common ingredient added to bricks to help strengthen and harden them. However, if the lime is not properly mixed in the clay and forms large lumps, it can create weak spots in the brick and make it more susceptible to cracking and breaking. Lumps of lime can also cause problems during construction, as they can make the brick more difficult to lay and can lead to uneven surfaces.
Overall, when bricks have one of these harmful ingredients, it can result in poor quality, strength and durability. Hence, it’s crucial to be aware of them and select bricks with minimal or no presence of these harmful ingredients.
Recall different Defects in Bricks: i. Chuffs, ii. Bloating, iii. Cracks, iv. Blistering
Defects in bricks can negatively impact the strength, durability, and overall quality of the brick, and can also cause problems during construction. The following are four common defects in bricks that it is important to recall:
- Chuffs: Chuffs, also known as “chicken heads” or “bullnoses,” are raised bumps or protrusions on the surface of a brick. They are caused by a buildup of gas in the clay during the brick-making process, which causes the surface of the brick to bulge. Chuffs can weaken the brick and make it more susceptible to cracking, and can also make the brick more difficult to lay and can lead to uneven surfaces.
- Bloating: Bloating occurs when the clay in the brick contains too much water or organic material. As the brick is heated during firing, the water or organic material expands and causes the brick to puff up, creating a distorted shape. Bloating can weaken the brick and make it more susceptible to cracking, and can also make the brick more difficult to lay and can lead to uneven surfaces.
- Cracks: Cracks can occur in bricks due to a variety of reasons such as overheating, thermal movements, contraction or expansion due to weather conditions, improper mixing of ingredients, or improper curing. Cracks can weaken the brick and make it more susceptible to breaking, and can also make the brick more difficult to lay and can lead to uneven surfaces. Cracks can also allow the entry of moisture and water into the bricks, which can cause issues with freeze-thaw cycles and can lead to structural failure.
- Blistering: Blistering is the formation of bubbles or raised areas on the surface of the brick. It is usually caused by the presence of water in the clay during the firing process, which causes the surface of the brick to bulge and blister. Blistering can weaken the brick and make it more susceptible to cracking, and can also make the brick more difficult to lay and can lead to uneven surfaces.
Overall, defects in bricks can make them weaker, lower quality and less durable. Also, defects can make it more difficult and costly to lay them, and can lead to uneven surfaces, therefore it’s crucial to be aware of these defects and select bricks with minimal or no presence of these defects.