[fso301]

So, you essentially take a ground, highly porous material, saturate it with water and use it as a portion of the fines?

[decimon]

So, you essentially take a ground, highly porous material, saturate it with water and use it as a portion of the fines?

I don't know. There is a 5 meg PDF at the link for anyone sufficiently interested.

[absalom01]

It’s conventional lightweight structural aggregate — (regional — here in So Cali it’s expanded shale, but other areas may use slate or clay). So it’s not really “highly porous”, but it does absorb some percentage of water (say 5-15%) over a 24 hour period.