What is the maximum limit of water-soluble content (percentage by mass) present in fly ash, which could be used as an additive to brick earth?

Question

Question

This question was previously asked in

BHEL Engineer Trainee Civil 24 Aug 2023 Official Paper

Answer 1

Explanation:

As per IS 11650:1991

5.2.1 Fly ask

Fly ash is a waste material available in large quantities from thermal power plants and can be mixed to the brick earth as alluvial, red, black, marine clays, etc, used for brick making.
The fly ash should preferably be fine textured, free from bottom ash, coarser and other extraneous material, with a fineness varying in the range of 2000 - 3000 cm²/gm.
The total water solubles in fly ash should be less than 0.1 percent and unburnt carbon preferably below 15 percent.
The Indian fly ashes contain amorphous glassy material, mullite, haematite, magnetite, etc, and show a chemical composition similar to that of brick earths. These silicates also help towards strength development in clay bodies on firing when mixed in optimum proportion depending on the physico-chemical and plastic properties of soils to be used for brick making.