Roman concrete secret and cement-based marine structures

Thanks. found it.

 

You can also get pozzolan from other sources - ag. The FlyAsh from coal power stations. Thats the more common source for Ferrocement yachts.

The article discusses the adavantages of the two types
Natural Pumice Pozzolan Significantly Improves Concrete Performance http://www.hesspumice.com/pumice-pages/pumice-uses/pumice-pozzolan.html

 

Basalt Mesh and or Re-bar is the latest and greatest. Basalt Mesh Geo-Grid reinforcement is better than steel https://basalt-mesh.com/

Basalt Rebar reinforcement is an alternative to steel and fiberglass for reinforcing concrete https://basalt-rebar.com/

 

Hmmm - not quite a sub. It has no provision for human life support, I presume the scuba divers sheltered behind the open cockpit, and pulled levers to empty the two flotation pods on each side to surface. Still. it was very innovative and a bit more interesting than just some sort of boat.

 

Technically, they've had the "secret" to Roman concrete for a while. It's marketed as "reactive powder concrete", and uses a different chemistry to portland cement. It's advantages are that it can be combined with Portland cement to make a concrete that's stronger than either would be by itself. It's also capable of being impermeable to ionic penetration. In other words, seawater won't leach into it. Here's an example of some of the stuff available to purchase:

Silica Fume, White, 50lb bag - Fishstone - Concrete Countertop Supplies http://www.concretecountertopsupply.com/Item/SilicaFumeBrightWhite50lb

 

Non-reactive fiberglass and basalt are both options.