August 8, 2020

Tests for the acceptance of bricks for building construction

Tests for the acceptance of bricks for building construction

1. Dimension and tolerance test
2. Compressive strength test
3. Water absorption test
4. Efflorescence test

1. Dimension and Tolerance Test: 

Take 20 bricks  out of given sample. The dimensions of 20 bricks  should be within the following limits

2. Compressive Strength Test:  
(i) Take five bricks out of the sample at random.  
(ii) Immerse the bricks in water at room  temperature for 24 hours.  
(iii) Fill the frags and all voids in the bed and  face with cement mortar 1:1.
(iv) Store the bricks under damp gunny bags for  24 hours and thereafter immerse them in  water for 72 hours.  
(v) Place compression testing machine  
(vi) Apply the load of a uniform rate of  140 kg/cm2 per minute till the brick foils  
(vii) Take the average value of the comp. strengths of the five bricks.  
(viii)The Compressive strength of a common brick  should be 50 kg/cm2.  
3. Water Absorption Test: 
If the water absorption capacity of a brick is more, its strength will be comparatively low. 
(i) Select ive bricks at random out of the given  sample.  
(ii) Dry them in a ventilated oven at 105 to 110C  till they attain practically constant weight.  
(iii) Remove the bricks from the oven and cool  them to room temperature.  
(iv) Weight the bricks in a balance. Let it be  W1 kg.  
(v) Immerse the five bricks in water completely  at 27± 2C for 24 hours.  
(vi) Remove one brick from water and wipe off  its surfaces with a damp cloth.  
(vii) Weight the brick within three minutes after  its removal from water. Let its weight be  W2 kg.  
(viii)Water absorption capacity =  (W2-W1/W1) x 100
(ix) Take the average value of the water  absorption capacities of the five bricks.  
(x) For 1st class bricks, the water absorption  capacity should not be more than 20% by wt.
4. Efflorescence Test: 
This test is performed to  know the presence of any alkaline malter in the  bricks. 
(i) Take five bricks at random from the given  sample.  
(ii) Place each brick on end in a dish containing  distilled water ensuring depth immersion at  least 2.5 cm.  
(iii)Keep the dish in a ventilated room (temp 20 to 30 C) till the whole of distilled water in the  dish evaporates. 
(iv) Again pore 2.5 cm depth of distilled water in the dish and keep it till whole of water gets evaporated.

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