What are the Properties Bricks you should know about?

A Complete Guide on Properties and Composition of Bricks

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Bricks are one of the oldest and most common types of building material which are generally used to construct walls, pavements, flooring, foundation cover, etc.

Physical and mechanical properties of bricks are the most vital ones. Durability, strength, size, shape, hardness plays a key role in the properties of bricks.

Due to the features like durability, cheapness, strength, hardness bricks are widely accepted and used worldwide.

After the completion of this article, you'll be able to answer the following:

• What are the bricks?
• What are the Properties of bricks?
• What are bricks made of?

Do you know what makes the bricks so durable, cheap and easily available material?

Well, the answer lies in the chemical composition of brick.

Not only that I will tell you more about the properties, composition, and uses of bricks.

Give me some moment you will definitely gain more knowledge about bricks.


Bricks can be defined as a rectangular building material used with mortar. Traditionally it referred to a construction element produced by clay but now it can be made of concrete, fly-ash, etc.

In the modern era, the traditional clay burnt bricks are evolved very much in terms of composition, quality, features, shape, etc.

Let's come to the point where we will find out the things that make the bricks so popular.

-Properties of bricks are also the major key role in brick's popularity.

➤ Properties of Bricks

PROPERTIES OF BRICKS

Before going into the discussion of properties of bricks, let me know you that there are three types of Clay-Burnt clay available.

• First-class bricks
• Second-class bricks
• Third-class bricks
• Fourth-class bricks.

Where the first-class refers to the most superior quality of bricks and the fourth-class represent the worst one.

All have their own uses in construction which I will discuss in another article.

The most important properties of bricks can be classified into three division:

1. Physical.
2. Mechanical.
3. Thermal.

➣ Physical Properties:

Well, physical properties can be defined by the characteristic of any substances which can be observed and measured without changing its composition.

Good quality bricks should have the following properties-

1. Colour

• Well, the first thing that we notice is its color. Reddish type of color is ideal for first-class bricks. 

•  Uniformity and the brightness of color should be maintained properly.

•  We must avoid dark blue and light yellow color of bricks as this indicates over-burning and under-burning respectively.

2. Size

• As per the Indian Stanard, the Size of bricks is  190 mm x 90 mm x 90 mm.

• The standard size of a brick( A/c to the US Standard) is 200 x 100 x 100 mm.

• It is necessary to maintain the standard size of bricks for construction work.

3. Shape

• It is already described that the ideal shape of bricks is the rectangular shape.

• It should have sharp and well-defined edges.

• Bricks surface should be even and regular.

4. Density

• The standard range of density of bricks is 1600 kg/cubic meter to 1900 kg/cubic meter.

• The density or weight/Unit volume depends upon the type of material used and the molding method.

5. Hardness

• One simple and easy way to test the hardness of bricks is the nail-scratching test.

• In this test, fingernail is used to scratch on the brick surface. If no scratch impression occurs on the surface then it is a type of hard bricks.

6. Soundness

• From the soundness test, you can judge a brick's quality. 

• When two bricks are rubbed with each other, it should produce a metallic sound.

➣  Mechanical Properties

Brick Wall

When we talk about the mechanical properties of bricks, strength comes first.

1. Compressive strength

This strength defines how much a matter can withstand compressive force without showing any significant failure.

There is a standard number for compressive strength of brick.

• As per Indian standard, Brick should have a minimum compressive strength of 35 kg/cm2

• You should remember that the strength of bricks depends upon the composition of brick and also the burning process.

• This strength may vary from 35 kg/cm2 to more than 200 kg/cm2 in India.

• Other than Compressive strength, flexural strength is also unavoidable.

• For residential purposes, the Minimum flexural strength of brick should not be less than 10 kg/cm2

• Whereas, that strength of first-class brick may vary from 50-70 kg/cm2

➣ Thermal Properties

• Thermal properties refer to the conductivity of brick. It is necessary that brick should have low thermal conductivity.

• This characteristic of bricks helps houses to keep warm in winter and cool in summer.

• In the case of Fire, the temperature can be controlled up to some extent.

There are some other properties such as water absorption, Frost resistance, efflorescence which defines the quality of good bricks.

➪ Water absorption

By using this test we can identify many characteristics of bricks such as weather resistance, durability, quality, etc.

Water absorption of bricks can be determined by the following formula:

Absorption=(W2 – W1 / W1) x 100

Where,
 W1= Dry weight of the brick sample
 W2= Weight of brick after 24 hours of water immersion.

This absorption value depends upon the ratio of the volume of pores in brick to the gross volume of brick.

In simple words, higher absorption value means that the brick sample can absorb a high amount of water.

-The problem occurs if the bricks sample gives high absorption value:

• Strength gets reduced
• Frost-action and efflorescence may occur due to a high water amount.
• The dampness of the brick sample.

For first-class bricks, the absorption value should not be more than 20%.

➪ Frost-resistant 

To know this defect you need to know that when water turns into ice, a 9% increase in its volume occurs.

This expansion is the main culprit for Frost defect in brick.

Due to the expansion, stress-induced within the brick which further leads to crumbling bricks.

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➪Efflorescence

Efflorescence defects in brick

Sometimes you may notice that a wall is covered with white powder.

The engineering term of the white powder is Efflorescence.

Efflorescence occurs in presence of water and makes a salty deposition on the brick surface.

High moisture content is the reason for efflorescence defect in brick.

➤What are The Bricks Made of?

The composition of bricks (%)

Here we will talk about the most classic form of brick- Burnt Clay Bricks.

Required Ingredients to make the bricks are the real reason behind its durability and cheapness.

Here I have provided a list of percentage of constituent materials presents in brick-

[ PEOPLE ALSO READ: Grade of concrete ]

As you can see the basic ingredients of Burnt clay brick are- Sand, Clay.

Let's discuss in brief about the role of each ingredient.

Silica

• Silica plays a key role in deciding the properties of bricks.

• A major component of burnt clay brick is silica as it covers more than 50% of brick weight.

• Silica presents in a free or combined form which helps to prevent the bricks from shrinkage, Cracking, and Warping.

• Percentage of silica present in brick is directly related to the uniformity. The more silica presents in brick mean it will be more uniform in texture.

• But, One thing you need to remember is that the excess amount of silica leads to a brittle and weak brick.

• So the right proportion of sand is very essential to make a good quality brick.

[Excess of anything is not good]

Alumina

• The 2nd most basic component in brick ingredients is Alumina. It is a must needed element for a brick formation which acts as a  binding or cementing material in raw brick.

• Usually, alumina is the main component of clay which imparts plasticity to the bricks.

• This plasticity characteristic of bricks ensures it can be molded in desired shape and size.

• If alumina presents more than permissible limit then it may lead to dry shrinkage and warping of raw bricks during the drying process.

Iron-Oxide

• Even though Brick contains very little amount of (Fe2O3),  it increases the overall durability, strength, and impermeability.

• Iron-Oxide imparts a reddish color to the brick.

• It helps to dissolve lime.
• Deficiency of Iron-Oxide brings yellowish color whereas the surplus of it causes the dark blue color of bricks.

Magnesia

• It is a well-known element used to reduce the shrinkage in brick.

• It gives a yellow shine to the brick.

• The overdose of MgO can lead to corrosion of brick.

• It enhances the properties of bricks.

Lime

• The brick contains a little amount of Lime in powdered form.

• It enhances the melting process for silica.

• During the burning process of brick, it helps to bind other components together.

• Which makes the bricks more durable and stronger.

Apart from the general components of bricks, some harmful ingredient also presents in brick which may affect the properties of bricks.



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Conclusion

In this article, we have discussed the following:

• What are the basic concepts of bricks?
• Physical, mechanical, thermal properties of the brick.
• Composition of bricks

Other than that Durability of bricks is also an important part of the properties of bricks.

Comment below your question.

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