Brick test

 TESTS FOR BRICKS

Different kind of test can be performed to check the quality of bricks for construction use. 

There are two places where you can perform the test

1. Laboratory 

2. On site

• Earlier the stone is main construction material but after the bricks are invented
• brick are more economical so the demand for bricks are increased.
• It also give the strength, durability reliability.
• To build good quality Structure good the quality of material also need to be good. To know the quality of bricks some test need to be performed to check the suitability of bricks for construction.

1. Absorption

Degree of burning ,quality and behavior of bricks in weathering can be determined by performing absorption test.Better resistance will be provided when water absorption is less than 7%.

Procedure:-

1) specimen of brick is first dried in a oven at the very temperature of 106 degree to 115 degree Celsius.

2) when the specimen is permitted to cool at room temperature.

3) The wait of the specimen and mass is noted (M1)

4) After specimen is submerged in water room temperature of 27 degree for 24 hours. 

5) Then specimen will be taken out and wipe the droplet present on specimen with clean cloth.

6) Specimen will be weighed.

for a period of 16 hours,

Formula for calculation:-

Result:-

In case, weight should not be surpassed:

(a) For first class bricks,20 per cent of weight of dry brick.

(b) 22.5 per cent for second class bricks,

(c) 25 per cent for third class bricks,

2. Crushing strength 

Bricks which are used for our construction are comes under compressive load so crushing strength of brickes need to be determined. It can also be called as compressive strength and it is a a chief test to find out brick behaviour under the compressive load.

Compression testing machine can be utilised to do perform crushing strength test.

1. Compression Testing Machine

2. Brick sample

3. Cement, sand, aggregate for specimen preparation.

Sample preparation:-

The brick sample is taken and all the unevenness should be removed.

The dimensions fully measured.

Then the sample is submerged in the water for as long as 24 hours and then after the 24 hours it allowed to dry up.

If the traces of of water droplet are present then it should be e wipe out buy a clean cloth.

After that cement mortar can be prepared and placed in the frog of specimen. But there may be some voice still present in the specimen it can be filled with cement mortar.

The mortar covered brick specimen is then stored in damp jute bags for 24 hours.

Bricks they need to to submerged inverter for 3 to 7 days to permit cement mortar to harden.

Procedure:-

Following steps should performed for the crushing strength test on bricks

1. The brick specimen which is filled with mortar which is in upward direction is placed in between  the the compression testing machine plates.
2. Then the load is applied uniformly at a rate of 14 Newton/mm^2 per minute until the specimen failed and the maximum load at failure is recorded.
3. Then the compressive strength of brick can be calculated by the formula
4. Minimum crushing strength for

• First class bricks      * 10 N/mm2 
• Second class bricks * 7.5 N/mm2

3. Hardness:-

• Hardness of the the brick can be determined by scratching with the help of fingernail. if no mark is produced on the brick surface, brick is treated to be relatively hard.

4. Presence of soluble salts

• Efflorescence on the surface of bricks can be caused if the soluble salts are present.
• It is immersed in water for 24 hours. It is then taken out and allowed to dry .
• Absence of soluble salts can be indicated by absence of grey or white deposit on the surface.
• If the white deposits cover about 10% surface, the efflorescence is said to be slight.
• When white deposit cover about 50% of surface thin it is said to be moderate.
• Efflorescence can be treated serious if the the grey and white deposit on the surface are more than 50%.

5. Shape and Size

• shape has to be true rectangular and sharp edges should be present.

• 20 bricks are randomly selected of standard size (19 x 9 x 9 cm) for good quality bricks, 

permissible limits:

Length - 368 cm to 392 cm

Width - 174 cm to 186 cm

Height - 174 to 186 cm

6. Soundness

•  Two bricks are struck with each other while performing the test.
•  The result in which brick specimen should not be  cut into two parts and clear ringing sound should be produced.

7. Structure

• The brick should be compact and without the defect such as lumps and holes.
• Temperature can be resisted by high duty fire clay are 1482°C to 1648°C.
• For medium duty fire-clay is 1315°C to 1482°C .
• And for low duty fire clays it can be up to 8 70 degree Celsius.

Classification of Bricks 

The bricks can broadly be classified into two categories: 

1. Unburnt Bricks: In this type of brick, bricks are dried with the help of of heat received from the Sun and this bricks can only be used for temporary and cheap construction. 

Those bricks cannot be used where rain is directly exposed.

2. Burnt Bricks: These are classified into following categories

 (i) First Class Bricks

This type of bricks are burnt in the kiln and are moulded with the help of table(stock board).

The surfaces and edges of the bricks are sharp square smoot and straight. 

All the qualities of good bricks are present in the first class brick and it is preferred for or chief and permanent construction works.

( ii ) Second Class Bricks

These bricks are ground shaped and they burnt in kilns. 

The surface of those bricks is some what  rough and shapes also slightly irregular. These bricks are generally utilised at places where bricks work is to be provided with the coat of plaster.

 iii ) Third Class Bricks are

These are ground shaped and they burnt in brace or Clamps .

Hardness of these bricks is less and they have rough surface and distorted edges .  

These bricks gives dull sound when struck together 

They are used for unimportant and temporary structures.

Size and weight of bricks:-

Standard size of bricks =19 cm x 9 cm x 9 cm 

Nominal size ( with mortar ) is 20 cm x 10 x 10 cm

 The largely adopted nominal size of traditional bricks is 23 cm x 11.4 cm x 7.6 cm .

 It is found that the weight of 1 m of bricks earth is about 1800 kg Hence the average weight of a brick will be about 3 to 3.5 kg

https://civilengineeringaasanhain.blogspot.com/ for More..