81. The tolerance in the width of mould of a class I brick is about

1. ± 6 mm
2. ± 3 mm
3. ± 12 mm
4. ± 10 mm

82. The maximum allowable water absorption (% by weight) of bricks conforming Class 17.5 of IS 1077 (1992) is

1. 8.25 %
2. 17.50%
3. 15%
4. 33%
5. 20%

83. Usually there is an increase in the volume of sand caused by the films of water pushing the sand particles apart. This effect is called as

1. Efflorescence
2. Caving
3. Boiling
4. Bulking
5. Expansion

84. A good brick earth should contain Iron oxide in the range of

1. 5-7%
2. 15-20%
3. 12 -15%
4. 20-25%

85. The process of mixing clay, water and other ingredients to make bricks is known as

1. Moulding
2. Kneading
3. Blending
4. Pugging

86. Heavy duty bricks used for bridges, foundation of industrial buildings, multi-story building, etc. have a compressive strength

1. less than 25 N/mm²
2. between 25 N/mm² and 30 N/mm²
3. between 30 N/mm² and 40 N/mm²
4. more than 40 N/mm²

87. Charpy’s V notch test is done on a building material to determine

1. Brittleness
2. Abrasion
3. Hardness
4. Elasticity

88. Pug mill is used for

1. Clay preparation
2. Clay moulding
3. Brick drying
4. Brick burning

89. The main function of Alumina in brick earth is to

1. impart plasticity
2. increase durability
3. prevent shrinkage
4. increase impermeability

90. What are the actual dimensions of a brick used in construction?

1. 20 × 9 × 9 cm
2. 9 × 9 × 9 cm
3. 10 × 9 × 9 cm
4. 19 × 9 × 9 cm