Geopolymer Concrete, the perfect seasteading material


I see your point regarding blocky vs. torus design. BUT, there is a good reason behind my design:

Modularity (or such degree of it) cannot be achieved with a torus design.

Docking another boat(s) to the structure will be very difficult alongside a torus design.


Well, don’t you have to use rebar for the torus? If so,curving the rebar to the torus design wouldn’t be more expensive (in man hours) than a straight rebar set up and also more complicated?

(Wilfried Ellmer) #23

A donut shape torus looks like a feasible way.
The pictures show light surface floating structures.
consider: any light surface floating structure brings up unconfortable movements unless it is built to a beam of around 100m. Only things that float ballasted and do not track the waves (like the ocean sphere) can be small and comfortable at the same time. It has to do with intermittent air liquid contacts and the movements that they introduce.
Do not allow such contacts except on the central axis…

in short:

Look for a floating status where the hull is under water (out of intermittent contact) and only a tower near the metacenter is looking out.

Basic seastead construction principles movements and intermittent air liquid contacts

LOL, there’s nothing “light” about the shown structure,…It’s 420’ x 225’ (140 m x 75 m), it weights A LOT and the motor yacht pictured off the port quarter dock is 80’ LOA.

A similar LOA submarine as the seastead above, floating as shown in your picture, will be “all over the place” in a heavy seas, doing much, much worst than the seastead. Keep in mind that they are both FLOATING in that heavy seas, no matter how ballasted they are,…

No matter the size, nowadays gyro stabilizers can solve most of the stability problems. The main questions (leaving modularity aside) are:

  • How do you build a torus 420’ x 225’?

  • How do you dock anything around the torus’s “flared up” hull at the water line? (unless the torus’s water line is right in the middle - meaning that the draft is equal to the freeboard - which in maritime terms we call “sitting heavy in the water”, therefore making the whole section of the torus above the water line “wet & miserable” even in light seas - unless, of course, it is a totally enclosed torus with no open decks.

But who would want a seastead with no open decks? :smiley:

(Wilfried Ellmer) #25

open decks in open sea are overrated - a small area will do. Cruisships are NOT built for open decks, modern designs are oriented to the inside type patio…for good and practical reasons…when a Draupner washes over you will be happy to have not too many people on open decks exposed.

The ocean sphere has the openness of a shopping center not of a wind and salt spray barren boat deck.

ocean sphere from below

ocean sphere from above ( a small water washed sun deck to be there in nice climate)

ocean sphere inside

the light and openness equivalent to a shopping center



(Anenome) #27

[quote=“octavian, post:22, topic:240”]

You might need 1’ thick walls and thrice the rebar with the shown design to achieve the same strength as a few inches of concrete using a curve-based design.

A flat plane is like a beam. Put a load in the center of a horizontal beam and it breaks at say X lbs.

Now let’s imagine an arch. An arch is a much stronger shape, it converts the load into compression.

A tube is basically a self-supporting arch all the way around in two dimensions, then extruded.

A sphere is an arch in three dimensions, and thus stronger than the 2d arch.

If a sphere section requires X amount of reinforcement, a tube requires 2X for the same strength yield. A flat wall might require 4x or more for the same strength.

And while you say this is to simplify construction, it actually could prove to be much more expensive and much less simple than what I’m about to propose to you.

Well, don’t you have to use rebar for the torus?

Sure you do, but a whole lot less. You can likely get away with 8" squares for the torus–that’s what the Monolithic people use. A tube needs twice that amount. A flat wall, probably twice again.

Although, there is one mitigating factor that I haven’t talked much about. Basalt rebar is considerably stronger than steel rebar, measured in gigapascals of tensile strength. But again, it’s for an architect to do the math on.

If so,curving the rebar to the torus design wouldn’t be more expensive (in man hours) than a straight rebar set up and also more complicated?

Basalt rebar is far more flexible than steel rebar. Where steel rebar has to be actively bent, basalt rebar can do easy curves in about 5’ radiuses. In fact it ships in coils and readily straightens out, spring-like. So as long as you have a design which doesn’t require a tight curve, you’re fine.

(Anenome) #28

[quote=“octavian, post:24, topic:240”]
No matter the size, nowadays gyro stabilizers can solve most of the stability problems. [/quote]
Sure, but once you get to a these sizes you don’t have to bother with gyros anymore. US warships have no gyros, just rely on mass for wave resistance. But British warships are smaller and still use huge gyros.

I did the math on this once. Take an 8" sewer pipe and curve it all the way around the entire structure, say 80’ diameter. Fill it with water and you’ll have several tons of weight in that structure. Attach the pipe to the structure with something like rollercoaster rail, hardy and strong, and rotate the whole mass at a few miles per hour, that’s all you need to generate a very significant gyroscopic force with that much weight. It wouldn’t be able to do active stabilization, but it would tend to resist any rapid angular changes.

The main questions (leaving modularity aside) are:

  • How do you build a torus 420’ x 225’?

With an airform, basically an inflateable mold. Go read up on Unfortunately their airforms don’t come cheap.

Alternately you could slipcast it horizontally, but there’d have to be a join at one end–which might actually work with your design since you have this open fishtail at the back. Maybe that’s where you could have boats enter and dock in the center of the torus.

  • How do you dock anything around the torus’s “flared up” hull at the water line?

Cut a hole as big as you like and put a dock in there. Or check out the Candock system, you could have a modular dock.

Reviewing DeltaSync’s construction estimates on the simple square Concrete Caissons
(Wilfried Ellmer) #29

I agree on the said about strength of curved walls (shells) compared to flat walls…my tests confirm that.


The reality of boat building is that you will always have bulkheads and reinforcing beams(frames), no matter if a boxy or torus design,…Therefore, it is highly unlikely you will need a 1 foot hull thickness on the boxy one. Most of the oil tankers have a steel hull thickness of 1 (one) inch.

In terms of docking, is not as simple as “cutting a whole and putting a Candock there”. Tons of cargo and hopefully thousands of passengers would have to be hauled in and out and up and down using access ramps, cranes, etc. Candocks won’t last a minute out there :smile:

And what they call “severe weather” (LOL, 5 foot breakers…) in the video, it’s actually a really nice day in the middle of the ocean. Any open ocean seastead design should be based on the “realities on the ground”, with the NORM being 10’ -15’ waves and blowing 15-20 knts, most of the time.

Don’t get me wrong, I do understand your arguments regarding toruses, spheres and cylinders and you have valid technical points there. What I am analyzing here is their functionality and efficiency for routine seasteading activities under normal sea state conditions “on location”.

(Wilfried Ellmer) #31

@octavian i don’t see open saltwater washed decks on the Oasis of the Seas. The “most open decks” are quite protected and start 30m above the ocean surface…looks they included Draupner into the design.

If you check on the “total real estate square meters” of the structure the “open deck area” is minimum, even smaller than a ocean sphere concept. And keep in mind Oasis of the Seas is a “sunshine cruse concept” designed to avoid bad wether on its path at all cost and only go from port to port never stay at open sea longer than strictly necessary.
In fact the decks are used when being in port mostly - not at open sea.

Finally there is not much “open deck” in land based housing either - in fact skyscrapers have non and living there is still very enjoyable. - as said “open deck is overrated” modern shopping centers have abolished the concept towards a more sophisticated “inner patio” as you see it also emerging in the design of the Oasis of the Seas…


I never said anything about “open saltwater washed decks”,…I said open decks, as in “under the sun” are desirable (to me). I don’t know what is overrated or not.

Also, I don’t think that building a “mallstead” is the “key” to seasteading :smiley:

(Wilfried Ellmer) #33

In Draupner conditions any deck not protected by a 15 m high bow and a even higer superstructure is a “saltwater washed deck”

(Wilfried Ellmer) #34

I am not proposing a “specific single thing” i propose a wide range of things to choose from, by any investor according his preference. I also propose some “universal principles” for how to put permanent living space a sea like the ramform and the ocean sphere.

(Bob LLewellyn) #35

[quote=“ellmer, post:31, topic:240”]
Finally there is not much “open deck” in land based housing either - in fact skyscrapers have non and living there is still very enjoyable[/quote]

Living in the city is enjoyable? Will, what planet did you say you was from? Here’s a hint, cities suck. They make parks so people can pretend to be alright but it doesn’t help, cities still suck.

(Mark Stephan) #36

Cities are good in the fact that they can bring resources and opportunities. Good restaurants, entertainment, etc. But nobody likes being crowded, pollution, commuting, crime, etc. We’ll just have to have some good restaurants and entertainment on our seasteads :smile:


Bob’s my man!

A seastead by nature is going to be a tight community. More like a condo association than a city or acreage. A neighborhood that is a community, that is a town, city-state, and country.

Still, everyone needs their privacy, maybe a private porch or garden or something.

Likewise, the thing that drives me nuts about cruise ships is the “shopping mall” atmosphere. It is total hell to be locked in a mall even for a couple days. I love cruises, but dislike the mall atmosphere and spend as little time as possible on the shopping decks.

(Wilfried Ellmer) #38

Urban settlement is the only solution on a 7 billion planet…only the oceans can provide the space resources necessary to accomodate human needs on the planet. Landspace needs to be built back for nature.

(Bob LLewellyn) #39

[quote=“MarkStephan, post:36, topic:240”]
. We’ll just have to have some good restaurants and entertainment on our seasteads[/quote]

Think about what it would be like to live there, ocean world. Water slides for the children to play on. Babies will learn to swim before they learn to walk. We’ll kick ass at every swimming competition. There’s no transportation, we will walk or swim everywhere. Teenagers will look forward to their first jet ski.

The Olympic size swimming pool is a floating cage, so you can safely swim with the fishes. Bubble bars where the night life is. It will be like living in a touristy beach town where the living never slows down. And it will make money, which means it will be self sustaining. Spring break, wow, what a concept.

Envision life on a seastead | oceanic business alliance
Envision underwater living space - perception error correction | oceanic business alliance
(James) #40

Have you considered adding aerogel to the mix, possibly as a filler (like small rocks in some concrete)?

(Dave Pennington) #41

Thank you for posting such useful information on geopolymers. It’s hard to find on the internet in such a concise form!

In 2010 I developed an insulated fiber cement composite
which I call “EPIC” (EPS + Paper Infused with Cement). This material
has been used to build affordable dome homes (under $10/sq ft) insulated aquaponic tanks (its
original purpose) and conventionally shaped homes of over 6,000 sq ft. (built by one of my students)

EPIC is made almost entirely of commonly available waste materials.
“Styrofoam” (expanded polystyrene or EPS) makes up the majority of
the bulk, and cellulose (either paper or wood fiber) make up the majority of
the structure. A variety of cements can be used to glue the composite together,
usually portland cement is sufficient, but many other binders and admixtures
have been successfully tested.

The mix design can be adjusted from very lightweight to very
strong. Generally it is best suited to compression loads but it also has
significant tensile and ductile strength. My most commonly used formula
develops a compressive strength of around 1,500 PSI. When cast into compound
curves this material can withstand very large forces. Once cured it is
impervious to damage from water, fire, insects and mold. (Note that I only have five years of
testing results) Note also that EPIC is not water-tight, it is water proof (undamaged by water). The outer surface in a marine environment would need to be covered with a watertight layer such as geopolymers. The airform process utilizes watertight plastic “balloons” which can serve this purpose, and which allows the structure (the torus is ideal) to be built from inside the “balloon”. I have worked with the Monolithic Dome Institute since 2009 they can make these balloons any size we need, out of materials which are extremely durable.

EPIC can be cast into almost any shape and machined more
easily than soft wood. All machined material can be recycled into new mixes, so
it is a zero waste product. Cured material can be easily attached to new
material without the “cold joint” issues typical of concrete
products. The curing process does not require heat or pressure.

I have developed several related processes,
including pneumatic forming techniques, grinding/packaging equipment and
methods for engaging communities to efficiently harvest and utilize materials
they normally pay to be rid of. A wide array of products have been made with
EPIC, and many more have been designed. This material is useful for making
durable lightweight structures of great beauty in an extremely cost effective
manner. It can be combined with geopolymers to create whatever structures we can dream up.