BRICK INFORMATION PART 2

1.TESTING OF BRICKS:-

The following tests are to  done for  it's suitability of construction works.

 (A)DIMENSION TEST(IS: 1077):-

• According to the IS 1077, Standard size of bricks are use.
• Dimension test of brick is tested by lying 20 bricks as shown in the figure below-

                               

(B) WATER ABSORPTION TEST(IS: 3495-PART-III):-

Percentage of water absorption given the indication of compactness which is induced from burning.

     

   (I) 24 HOURS IMMERSION COLD WATER TEST-

• Dry bricks are kept in oven (110-115℃) up to gain constant mass.
• After cooling the brick to the room temperature and recorded the weight as W1 .
• Bricks are now immersed in water at a temperature 27०±2०C for 24 hours.
• After that bricks are removed and recorded the weight as W2 after 3 min.

                                             

  Limitation of water absorption of some bricks

     (II) 24 HOURS IMMERSION COLD WATER TEST-

•  Weight the oven dried brick as W1 and then it is immersed in the water and boiled for five hours.After five hours it is cooled down to 27०±2०C by natural loss of heat within 16-19 hours and then taken out and wiped with wet cloths and recorded weight as W3 

                                         

(C)COMPRESSION STRENGTH TEST (IS:3495-PART-I):-

Compressive stress of bricks provide idea if compressive property of the bricks but practically it's very little value in  determining the strength of wall, though the strength of the wall is mainly provided by the morter.

• Brick is immersed in the water for 24 hours.
• After that the frog of the brick is filled flush with 1:3 morter and stored under damp jute bag for 24 hours and followed by immersed in water for 3 days.
• Now bricks are placed in compression testing machine and loading applied at uniform rate of 14 N/mm^{2  and maximum load at when the brick is fails, is recorded as compressive strength.}

(D)EFFLORESCENCE TEST(IS: 3495-PART-III):- 

• Brick is kept on 150 mm dia glass plate with 25 mm depth water at temperature of 20-30°C till the whole water is absorbed or evaporated.
• Now again water is filled up to 25 mm depth and allow to absorbed or evaporated by the bricks.
• After the bricks are examined after second evaporation and area of white pitches is measured on bricks.                                     
• Specification limit the efflorescence to be not more than moderate (10-50%) for up to class 12.5 and not more than slight (<10%) for higher class. 

(E) WARPAGE TEST(IS: 3495-PART-IV):-

Warpage of bricks is measured by a flat steel or glass surface.Measuring ruler graduated in 0.5 mm division or wedge of steel 60 x 15 x 15 mm.

   (I) CONCAVE WARPAGE:

• Flat surface of the brick is placed along the surface and measured selection location that gives the greatest deviation from straightness greater distance of brick surface from the edge of straightness is measured by a steel ruler or wedge.

     (II) CONVEX WARPAGE:

• Brick placed on the plane surface with the convex surface in contact with the flat surface and the distance of form corner of brick are measure from flat surface,largest distance is reported as warpage.

   Higher value of the distance measured in concave and convex warpage tests is taken is warpage.

2.DEFECTS OF BRICKS:-

 There are various type of defects are occurred in bricks.

(A) OVER-BURNING OF RICKS:-

• When bricks are over burnt, a soft molten mass is produce and the bricks loose their shape. this type bricks are not use for construction uses.

(B)UNDER-BURNING OF BRICKS:-

• If the brick is under burnt the clay is not properly softened because of insufficient of heat and the pores are not close. In this phenomena the bricks are not gain their actual compressive strength and the degree of water absorption is also increase.Such bricks are also not for construction works.

(C)BLOATING:-  

• A spongy swollen mass is produced over the surface of burned bricks. Due to the presence of of excess carbonaceous matter and sulphur in brick clay this phenomena is occurred.

(D)BLACK CORE:-

• If bituminous matter and carbon contains in brick clay and they are not completely oxidation, the brick results in black core.It is  mainly due to improper of burning.

(E)EFFLORESCENCE:-

• Grey or white powder patches appear on the brick surface because of alkalies present in bricks.When bricks come in contact with moisture, water is absorbed and the alkalies crystalise.

 

(F)CHUFFS:-

• Deformation of the shape of the bricks due to rain water falling on hot bricks.

(G)CHECKS:-

• When bricks come in contact with water, the absorbed water reacts with lime nodules causing expansion and consequent disintegration of bricks. Also Shrinkage and burning cracks result when excess of water is added during manufacturing of bricks.

(H)SPOTS:-

• If sulphide is present in brick, it cause dark spot on the brick surface, which is not suitable for open masonry.

(I)BLISTER:-

• Broken blisters are generally caused on the surface of sewer pipe and drain tiles due to air imprisoned in the time of moulding.

(J)LAMINATION:-

• Lamination generally cause due to entrapped air in the voids of clay and produce thin lamina on the brick surface which is weather out on exposure.Such type of bricks are not suitable for structure.