The unit is N/mm2 - This should be in between 10 and 12.5 for burned clay bricks.
The unit of density is Kg/m3 the density of normal clay products is 1200 to 1250.
Water absorption should not be more than 15% of the self weight of the product.
This is a white patches which will occur over the bricks due to the
The unit is Minutes - The material should not catch fire even it is exposed to fire up-tp 30 Mins.