RicodJour writes:

Hydraulic cement expands as it sets, sets in the presence of
active water leaks, has about double the strength of ordinary cement
and is waterproof.

Read the MSDS of the product you cited:

http://www.unitex-chemicals.com/msds...lic_cement.pdf

Where the "hydraulic" cement is shown to be ... ordinary portland cement.

Ordinary portland cement is "hydraulic", whatever that means. In civil
engineering it just means "sets by addition of water". But at some point
is came to mean, "meaningless term that gets suckers to pay multiples of
the price for ordinary portland cement". Magic stuff to put in cracks to
stop leaks. It's just ordinary portland cement with an accelerant, folks,
which mixes with water and works in immersion just fine.