TEST FOR BRICKS FOR BUILDING CONSTRUCTION | CIVIL ENGINEERING ONLINE QUIZ

Tests for the Acceptance of Bricks for Building Construction. | Civil Engineering Online Quiz

Tests for the Acceptance of Bricks for Building Construction. | Civil Engineering Online Quiz

Before accepting the bricks for building construction, the following tests are generally performed.

1. Dimensions and tolerances test 

2. Compressive strength test

3. Water absorption test

4. Efflorescence test

1. Dimensions and tolerances test. 

This test is per formed to know the accuracy of the dimensions of the bricks.

Procedure:

1.Take twenty bricks out of the given samples.

2. Remove loose particles of clay and small projections from the bricks.

3. Arrange them on a level surface in contact with cash other and in a straight line.

4. Measure the overall length of the bricks having size 19 x 9 x 9 cm laid by means of a steel tape.

5. The dimensions of 20 bricks should be within the fol- lowing limits:

Class A -

length - 368cm to 392cm, width - 174cm to 186cm , height - 174cm to 186cm

Class B -

length - 350cm to 410cm, width - 165cm to 195cm , height - 165cm to 195cm

2. Compressive strength test. 

This test is performed to determine the crushing strength of bricks

Procedure:

1. Take five bricks out of the sample at random.

2. Immerse the bricks in water at room temperature for 24 hours.

3. Take out the bricks from the water and wipe off surplus water from their surfaces.

4. Fill the frogs and all voids in the bed and face with cement mortar 1:1(1 cement: 1 clean sand).

5. Store the bricks under damp gunny bags for 24 hours and there-after immerse them in water for 72 hours.

6. Take out the bricks from water, wipe off dry. Place the bricks with flat surfaces horizontal and mortar filled frog face upward between two or three thin ply sheets and centre them between the plates of a compression testing machine.

7. Apply the load at a uniform rate cf 140 kg/cm² per minute till the brick fails.

8. Take the average value of the compressive strengths of the five bricks.

9. The compressive strength of a common brick should be 50 Kg/cm

3. Water absorption test.

 This test is performed to determine water absorption of the bricks. If the water absorbtion capacity of a brick is more, its strength will be comparatively low

Procedure:

1. Select five bricks at random out of the given sample.

2. Dry them in a ventilated oven at 105 to 110 till they attain practically constant weight.

3. Remove the bricks from the oven and cool them to room temperature.

4. Weigh the bricks in a balance. Let it be W1 kg

5. Immerse the five bricks in water completely at 27° ± 2C for 24 hours.

6. Remove one brick from water and wipe off its surfaces with a damp cloth.

7. Weigh the brick within three minutes after its removal from water. Let its weight be W2 kg,

8. Water absorption capacity =((W2-W1)/W1)x 100.

9. Take the average value of the water absorption capacities of the five bricks.

10. For First Class bricks, the water absorption capacity should not be more than 20% by weight.

4. Efflorescence test. 

This test is performed to know the presence of any alkaline matter in the bricks.

Procedure:

1. Take five bricks at random from the given sample.

2. Place each brick on end in a dish containing distilled water ensuring depth immersion at least 2.5 cm.

3. Keep the dish in a ventilated room (Temp. 20° to 30°C) till the whole of distilled water in the dish evaporates,

4. Again pour 2.5 cm depth of distilled water in the dish and keep it, till the whole of water gets evaporated.

5. Now, examine the bricks for efflorescence as detailed below :

Observation & Result:

(1) No perceptible deposit = Nil efflorescence

(ii) 10% area covered with thin deposit of salts=Slight-efflorescence

(iii) 50% area covered with deposit of salts without any powdering or flaking surface=Moderate-efflorescence

(iv) 50% area covered with deposit of salts accompanied by flaking of surface.=Heavy-efflorescence

(v) Heavy deposits of salts ac companies by flaking of the surface.=Serious efflorescence