TYPES OF TEST ON BRICKS - IS code 3495 - civil engineering study

Types of Tests On Bricks IS code 3495 

Following tests are conducted on bricks to determine its suitability for construction work.

• Absorption test
• Crushing strength test
• Hardness test
• Shape and size
• Color test
• Soundness test
• Structure of brick
• Presence of soluble salts (Efflorescence Test)

 

 WATER Absorption Test on Bricks - 3495 PART 2

• Absorption test is conducted on brick to find out the amount of moisture content absorbed by brick under extreme conditions. 

Apparatus:

• Oven, 
• Weight balance, 
• Tray

PROCEDURE

• Take any five random bricks from a lot of brick as a specimen.
• Dry the specimen in a ventilated oven at a temperature of 105°C to 115°C till it achieves considerably constant mass.
• Cool the specimen to room temperature and take its weight (M1).

Testing:

• When the specimen is completely dry, then immerse it in the clean water at the room temperature (27 ±2°C) for 24 hours.
• Remove the specimen from the water after 24 hours and wipe out water with a damp cloth and weigh the specimen.
• Take the weight (M2) of the specimen after 3 minutes of removing from the water.
• Points to be Taken Care:

• When you take M1, If the Specimen is warm while touching, it shall not be used for the test. Test it when you feel it cool.

Result:

• Note down the M1 and M2.
• Percentage of Water absorption of brick by its mass, after 24-hour immersion in cold water is calculated by the following formula
• (M2-M1)/M1*100

• For a good quality brick the amount of water absorption should not exceed 20% of weight of dry brick.

TYPE                         WATER ABSORBTION

FIRST CLASS         < 20%     OR 15% AVERAGE

SECOND CLASS     < 22.5%  OR 20% AVERAGE

THIRD CLASS         < 25%      OR 25% AVERAGE

 

Crushing Strength or Compressive Strength Test on Bricks - IS 3495 PART 1

• Place the specimen with flat face s horizontal and mortar filled face facing upwards between plates of the testing machine.
• Apply load axially at a uniform rate of 14 N/mm2 (140 kg/cm2) per minute till failure occurs and note maximum load at failure.
• The load at failure is maximum load at which the specimen fails to produce any further increase in the indicator reading on the testing machine.

•  Compressive Strength of Bricks = Maximum Load at Failure (N)/Average area of bed face (mm2)
• The average of result shall be reported.

• Crushing strength of bricks is determined by placing brick in compression testing machine. 
• After placing the brick in compression testing machine, apply load on it until brick breaks. 
• Note down the value of failure load and find out the crushing strength value of brick. 

compressive strength in N/mm2

>10.5     first class

7.5  second class

5.5  third class

 

compressive strength of common bricks should not be used if it is  less than 3.5N/mm2

 

 

Bricks Class Designation	Average compressive strength of Bricks
	Not less than (N/mm2)	Less than (N/mm2)
350	35	40
300	30	35
250	25	30
200	20	25
175	17.5	20
150	15	17.5
125	12.5	15
100	10	12.5
75	7.5	10
50	5	7.5
35	3.5	5

 

Efflorescence Test on Bricks - IS 3495 PART - 3

• A good quality brick should not contain any soluble salts in it. 
• If soluble salts are there, then it will cause efflorescence on brick surfaces.

Type	area affected
Nill Effloresence	Very Low
Slight	0-10%
Moderate	10-50%
Heavy	>50%
Serious	>50% + deposit are  present in powder forms Heavy Flakes

 

WARPAGE TEST - IS 3495 PART 4

• check the bricks for warpage of brick like concave and convex warpage with the help of glass or stell surface

 

Hardness Test on Bricks

• A good brick should resist scratches against sharp things. 
• So, for this test a sharp tool or finger nail is used to make scratch on brick.
•  If there is no scratch impression on brick then it is said to be hard brick.

for any doubt finger nail means

 

Shape and Size Test on Bricks (dimension test) - IS 1077

• Shape and size of bricks are very important consideration. All bricks used for construction should be of same size. The shape of bricks should be purely rectangular with sharp edges.
• Standard brick size consists length x breadth x height as 19cm x 9cm x 9cm.
• To perform this test, select 20 bricks randomly from brick group and stack them along its length , breadth and height and compare. 
• So, if all bricks similar size then they are qualified for construction work.

 

Dimension Test

Dimension should not greater than below value Length -19×20= 380 ± 12 cm Breadth - 9×20 = 180 ± 6 cm Height - 9×20 = 180 ± 6 cm here 20 indicate 20 no of bricks used in sample

 

Color Test of Bricks

• A good brick should possess bright and uniform RED color throughout its body.

 

Soundness Test of Bricks

• Soundness test of bricks shows the nature of bricks against sudden impact.
• In this test, 2 bricks are chosen randomly and struck with one another. 
• Then sound produced should be clear bell ringing sound and brick should not break. 
• Then it is said to be good brick.Soundness Test of Bricks

 

Structure of Bricks

• To know the structure of brick, pick one brick randomly from the group and break it. 
• Observe the inner portion of brick clearly. It should be free from lumps and homogeneous.Structure of Bricks

 

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