ZONOLITE products for light weight concrete
The Perlite of choice is Industrial A light or a bit stronger and heavier choice is Industrial A Heavy.
Both are like course sand and used in applications where light weight is important.
For vermiculite Pool Pad is a great choice.
All the above come in 4 cubic foot bags and are usually cheaper than the garden center varieties so worth looking around for.
In fact you can buy a Readymix of Pool Pad Vermiculite Portland cement and admix.
It's used in swimming pool construction.