Refractory bricks resists

• High temperature

• Dampness

• Chemical action

• Shocks and vibrations

The natural moisture formed in freshly quarried stone is known as  _________

The specific gravity of bitumen is

• 0.8

• 0.9

• 1.09

• 1.25

Efflorescence is caused by

• Low silica content of bricks

• High pH content of water used during pugging

• Presence of alkaline salts

• All of the above

The density of concrete is

• 28kN/m3

• 26kN/m3

• 20kN/m3

• 16kN/m3