**Compressive strength/ crushing strength of brick in N/mm2 & kg/cm2**, hi guys in this article you know about compressive strength of first class brick & fly ash brick in N/mm2, kg/cm2 and kN/m2 and also know about compressive strength of brick test.

**Compressive strength/ crushing strength** refers to the ability of a certain material or structural element to withstand loads that reduce the size of that material, or structural element, when applied. A force is applied to the top and bottom of a test sample, until the sample fractures or is deformed.

Once the deformation is concentrated in one area, the plastic flow stops and the material breaks. For ductile metals, tensile strength is usually the preferred indicator for measurement and comparison. This is because **tensile stress** measures the forces needed to pull a material apart, which is better suited to the plastic flow phenomenon.

**Compressive strength or crushing strength of brick in psi (pound square inches)**

In United States, based on Imperial measurement system, US customary units, compressive strength or crushing strength of brick measured in psi (pound square inches). Bricks are many types first class brick, second class brick, 3rd class brick, sun-dried brick, fly ash brick, AAC Block and concrete block.

Typically, compressive strength or crushing strength of brick is ranging between 1000 psi to 1500 psi, in general, compressive strength of 1st class brick is around 1493 psi, for common building bricks, their compressive strength is around 498 psi, for second class brick, their compressive strength is around 996 psi, for sun dried brick, their compressive strength is around 356 psi, for fly ash brick, their compressive strength is around 1422 psi and for AAC block, their compressive strength is around 570 psi.

**Compressive strength/ crushing strength of brick test** is calculated by using the equation, **F= P/A** Where, F= Compressive strength of the brick (in N/mm2). P= Maximum load applied to the brick (in N). A= Cross sectional area of the specimen (in mm2).

**Compressive /Crushing strength of bricks are very variable, and may vary from 30 kg/cm2 to 150 kg/cm2.**

**Compressive strength/ Crushing strength of brick**

1) compressive strength of first class Common building brick is 105 kg/cm2, 2) compressive strength of second class brick is 70 kg/cm2, 3) compressive strength of common building brick is 105 kg/cm2, 4) compressive strength of sun dried brick is 15 – 25 kg/cm2, 5) compressive strength of fly ash brick is 90 – 100 kg/cm2 and 6) compressive strength of AAC block — 30-40 kg/cm2.

Compressive strength/ crushing strength of brick calculated in N/mm2, kg/cm2 and kN/mm2.

**Fly ash bricks** are suitable for use in masonry construction just like Common burnt clay **bricks**. In fact, **Fly Ash Bricks** are twice stronger than normal clay b**ricks, compressive strength of fly ash brick is 120kg/cm2.**

And for hand-made burnt bricks, while Crushing strength of heavy duty bricks machine pressed (also called engineering bricks) may have compressive strength as high as 450 kg/cm2, and even 500 kg/cm2.

**Compressive strength/crushing strength of brick in kg/cm2**

Brick are of many type first class brick, second class brick,third class brick,sun dried brick, fly ash brick & AAC block.

**There are following compressive strength/crushing strength of different types of brick in kg/cm2**

● Common building bricks—35 kg/cm2

● Second class bricks—70 kg/cm2

● First class bricks— 105 kg/cm2

● sun dried bricks— 15 – 25 kg/cm2

● fly ash bricks— 90 – 100 kg/cm2

● AAC block — 30-40 kg/cm2.

**Compressive strength/ crushing strength of brick in N/mm2**

Brick are of many type first class brick, second class brick,third class brick,sun dried brick, fly ash brick & AAC block.

**As we know 1kg/cm2 = 0.0981N/mm2, so 35 kg/cm2 = 35×0.0981 =3.43N/mm2**

There are following compressive strength/crushing strength of different types of brick in N/mm2

● Common building bricks—3.43 N/mm2

● Second class bricks—6.867N/mm2

● First class bricks— 10.3N/mm2

● sun dried bricks— 1.47 – 2.45 N/mm2

● fly ash bricks— 8.82 – 9.81 N/mm2

● AAC block — 2.943- 3.92N/mm2.

**Compressive strength/ crushing strength of brick in kN/m2**

Brick are of many type first class brick, second class brick,third class brick,sun dried brick, fly ash brick & AAC block.

As we know 1N/mm2 = 1000kN/m2, so 3.43 N/mm2 = 3.43×1000 =3430kN/m2

**There are following compressive strength/crushing strength of different types of brick in kN/m2**

● Common building bricks—3430 kN/m2

● Second class bricks—6867kN/m2

● First class bricks— 10300kN/m2

● sun dried bricks— 1470 – 2450 kN/m2

● fly ash bricks— 8820 – 9810 kN/m2

● AAC block — 2943- 3920kN/m2.

**Compressive strength/crushing strength of 1st class brick**

The first class brick are used to form brick wall & retaining wall in masonry work, they emit a clear ringing sound when two bricks are struck each other.

105 kg/cm2 or (10.3N/mm2 and 10300kN/m2) is compressive strength/crushing strength of 1st class brick.

**105 kg/cm2 is minimum compressive/crushing strength of first class brick.**

Water absorption of brick : The strength of bricks decreases by about 25 per cent when soaked in water.

Water absorption of bricks after 24 hours immersion:>

First class bricks—20%,

Second class bricks—22 %,

Third class bricks—25%.

**Compressive strength/crushing strength of brick test**

These tests ( compressive strength of bricks have been described in detail in relevant codes prepared and published by Bureau of Indian Standards.

In this article, we give only an outline of most important points of these tests.

**Compressive Strength/crushing strength of Bricks Test. (ISS: 1077-1970)**

● Take five random bricks samples and immerse them in water for 24 hours at room temperature.

● After 24 hours, take them out, allow them to drain and then clean the surplus water. ‘

● Now, fill their frogs (and any other voids) by a layer of standard 1:1 mortar (1 part cement and 1 part sand).

Store these bricks under damp sacks for 24 hours (to allow setting of mortar).

● Place the bricks in water for seven days. (This is to allow the mortar to harden).

● Take the bricks out of the water, allow the water to drain and remove the surplus water. When surface dry, each brick is tested for compressive strength individually.

● Place the brick flat-wise, with frog end facing upward, between two plywood sheets.

● Brick so adjusted between the plywood sheets is placed on the bed of compressive strength of bricks testing machine and load is applied axially and at a uniform rate of 140 kg/cm2/minute. (This is very important).

● Note the load at which the brick fails (gets broken). This load (P) is divided by cross-sectional area (A) of the brick gives the compressive strength F.

F=P/A

● The arithmetic mean of the compressive strength/crushing strength of bricks values of all the five bricks shall be taken as the compressive strength of that lot of bricks represented by the test samples, (and not for all the bricks of a kiln).

● The brick shall be classified accordingly on the basis of the compressive strength obtained as above.

#Summary: Compressive Strength/ crushing strength of Bricks are follow:-

(i) Compressive Strength/ crushing strength of first class brick is 105 kg/cm2.

(ii) Compressive Strength/crushing strength of 2nd class brick is 70 kg/cm2.

(iii) Compressive Strength/crushing strength of common building brick is 35 kg/cm2.

(iv) Compressive Strength/crushing strength of sun dried brick is 15 to 25 kg/cm2.

**Compressive strength/crushing strength of fly ash brick**

Fly ash bricks are manufacturing by mixing Quarry Dust / River Sand , Stone aggregates less than 6mm in Size, Cement and Fly Ash ( Fly Ash quantity will be 10% to 20% of Cement ).

Normally the actual cement quantity required will be replaced with 10% to 20% Fly Ash. Any brick contains cement will increase the heat inside building.

Fly Ash Bricks with plastering on both sides will again increase more Heat . When we are manufacturing One Metric Ton of Cement equal quantity of CO2 ( Carbon di Oxide ) will also get generated . So we are poluting the atmosphere.

Compressive strength/crushing strength of fly ash brick calculated in kg/cm2,kN/m2 & N/mm2, their value are following:

● 90 – 100 kg/cm2 or 8.82 – 9.81N/mm2 or 8820 – 9810 kN/m2 is compressive strength/crushing strength of fly ash brick.

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M ramkumar says

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