INormal cement and is around 2.5 kg/m^2  .  This is made of 5parts stone 2 parts sand and 1 part cement.

What is being proposed I think is that instead of using cement which is cooked limestone we use a fire resistant polymer and old crushed glass ceramics and tiles as the ballast.

My question is why not make breeze blocks from the scrap ballast and avoid polymer?  

The answer  could be the thermal insulation rating for house building is better.  Hope the OP PonsianR will enlighten us soon.

INormal cement and is around 2.5 kg/m^2  .  This is made of 5parts stone 2 parts sand and 1 part cement.

What is being proposed I think is that instead of using cement which is cooked limestone we use a fire resistant polymer and old crushed glass ceramics and tiles as the ballast.

My question is why not make breeze blocks from the scrap ballast and avoid polymer?  

The answer  could be the thermal insulation rating for house building is better.  Hope the OP PonsianR will enlighten us soon.