GATE-2013 (28), The Void ratio (in percentage) of sandstone is 25. Its porosity in percentage is

28) The Void ratio (in percentage) of sandstone is 25. Its porosity in percentage is

(Thanks to Chandrasekhar, ANU)

Solution:

Given that the void ratio (e) = 25 % = 0.25

Porosity ($\phi$) = ?

We know the relation between the void ratio and the porosity as

$ porosity (\phi)=\frac{void ratio(e)}{1+ void ratio(e)}$

$\phi= \frac{e}{1+e}$

$\phi= \frac{0.25}{1+0.25}$

$\phi= \frac{0.25}{1.25}$

$\phi= 0.2$

$\phi$ = 20%

GEOPHYSICS