SSC JE Civil Engineering 30-Oct-2020 Shift 2 Paper

Explanation:
The composition of good brick earth:
1) Silica
● Good brick earth should contain 50 – 60% of silica.
● It prevents cracking, shrinking and wrapping of raw bricks.
● Silica imparts uniform shape to the bricks.
● Excess of silica makes the bricks brittle.
2) Alumina
● Good brick earth should contain 20 – 30% of Alumina.
● Alumina imparts plasticity to the earth so that it can be moulded.
● If it is excess raw bricks shrink and warp during drying and burning.
3) Lime
● It should not be greater than 5% for good bricks
4) Iron oxides
● It should be in the range of 5 – 6% for the good bricks.
● It imparts colour to the brick.
5) Magnesia
● It imparts color to the brick.
● It also decreases shrinkage in the bricks.