Geopolymer Concrete, the perfect seasteading material


(.) #204

Well, yes and more, because Cl2 chlorine gas gets dissolved after a reaction with
sodium hydroxide resulting sodium chloride and sodium hypo-chloride…


#205

Starting with a salt-water solution, (NaCl + H20), removing Chlorine and Hydrogen leaves Sodium Hydroxide. However, I have no idea, since it uses alternating current, how to sort the Chlorine gas from the Hydrogen. Both would form on both electrodes, so they would be mixed gases.


(.) #206

Diode will let current flow in one direction only.
Install a diode before one of the electrodes.


(.) #207

Are you using 110V AC for seawater electrolysis?


#208

Need alternating current to release the chlorine and create the lye. It’s a specific method.


(.) #209

You know abut this more than me.


#210

Weird. The alternating current method was the only one I could find, yesterday, now I’m finding Direct Current method… Grrr. I hate it when one site says it’s the only way to do it, and it’s a lie…

Bad joke: They lied about making Lye, so they were Lying about Lying…

http://science.jrank.org/pages/2351/Electrolysis-Production-sodium-hydroxide-chlorine-hydrogen.html


(.) #211

That is a common phenomenon, and not only about the lye.


(.) #212

In a seasteading environment it would be probably 12 V DC, provided by
photo voltaic solar panels.


#213

Here’s a good overview of the classic chloralkali (also chlor-alkali and chlor alkali) reaction:
https://en.wikipedia.org/wiki/Chloralkali_process

I urge you to purchase Sodium (or Potassium) hydroxide, rather than trying to make your own, because (1) the Chlorine is VERY TOXIC, (2) that reaction uses lots of energy, and (3) if you buy your lye in dry form, you can dilute to your preferred concentration. (After carefully reviewing how one safely dissolves lye in water.)


#214

Geopolymer experimentation continues…

Tonight, I mixed Charcoal Briquette ash in a 70/30 ratio with Diatomaceous Earth, with that mixed 40/60 ratio to general purpose sand. When mixed with water, to activate the process, this became mildly exothermic. It’s at roughly 78F, in a 73F room… Reached about 80*F, before I got it packed into the cup and packed down.

The purpose of Briquette ash is easy access to a source of metakaolin clay and wood ash as a source of lye.

Also mixed a batch of 3/3/4 Fullers’ Earth/Diatomaceous Earth/Wood ash, in a 40/60 ratio with sand. It’s holding at room temp.


#215

Addendum:

The Charcoal Briquette formula is a starting point for using common waste products. Metakaolinite is also commonly referred to as fly-ash, clay is to most common binder in charcoal briquettes, here, in the US; while wood ash is a common source for homemade lye (Sodium Hydroxide).

Metakaolin is a reactive clay, caused by high-temperature heat. the clay binder slows the overall burn rate for the carbon particles, but gets treated, so a cheap diy source of both is the briquettes…


#216

I suspect that your charcoal briquette ash has substantial Potassium Carbonate, maybe even more than it is -Hydroxide. Still pretty alkaline. And I sure hope you put those briquettes to good use (like some chicken and ribs. :wink:


#217

Water added, to activate the reactions would reduce Potassium Carbonate to Potassium Hydroxide, and CO2, which is a desired reaction. That one, I could smell starting to cook, which gives me high hopes.

Certainly want to avoid Calcium, though. The reactions involving that are generally reversible with heat added, and/or water soluble, so more prone to failure…


(Wilfried Ellmer) #218

It is probably a good idea to keep an open mind on the binder component of composite construction materials in general. The logical starting point seems to be portland cement but this is just a first step of a journey where we might end up with quite “exotical construction materials” in the end. (ref 86)


#219

The problems with OPC are multiple, from a practical point of view. For one, if using an iron based armature and components, such as a ferro-cement type hull, there will be Chlorine ion infiltration, in seawater, eventually leading to corrosion., another is bi-metallic corrosion, which can even be caused by making an electrical shore connection, in a marina. A third would be the potential loss of integrity, if there is a fire. if we are planning to build for centuries, rather than creating things that may last a couple hundred years, then we need to use the best materials available, not just the same old stuff that has failed to create permanent infrastructure. Just look at the reports of failed bridges and buildings, due to the internal corrosion of their steel armatures, as well as the acknowledged probability that, in the US, alone, it is estimated that 70,000+ of such existing structures are ready to fail.

The nice thing about the known chemistry of geopolymers, is that they are so Basic (High numeric pH value), as to prevent the corrosion, by inhibiting the infiltration of the ions, so long as there is structural integrity. Add that, in cases of repairs, OPC is difficult, at best, to get to adhere to cured OPC, while it has been demonstrated that geopolymers will bind to existing cured geopolymers with nearly the same strength as the original material, before the damage occurred.

Add that, by eliminating high concentrations of Calcium, geopolymers become mostly X-ray transparent, allowing for existing field technology to provide a complete examination of internal structure, for inspection purposes.


#220

In and amongst, I have a sample that turned-out well… Had to figure out the off-beat side reaction, but all in all, a nice, strong batch.

Used Charcoal briquette ash, in a 70/30 mix with Diatomaceous Earth
(quickie substitute for Fly Ash and Wood ash)

That was mixed 40/60 with Lowe’s General Purpose Sand
(all measurements by weight, using digital kitchen scale)

Added enough water to make a roughly mortar-thickness mud, and packed it into a 5oz plastic cup.

Mildly exothermic (~80F, in a 73F room). some mild off-gassing, primarily CO2, from the Potassium Carbonate, with water coming out, in dissolution, and evaporating, leaving behind what I presume is Potassium Nitrate, as a precipitate. unscientific, but mildly salty white powder, less salty that table-salt.

The mix hardened really well. Waiting for remaining off-gassing to end, before doing any testing.


#221

A novel method to produce dry geopolymer cement powder

H.A. Abdel-Gawwada, , , S.A. Abo-El-Eneinb

Open Access funded by Housing and Building National Research Center
Under a Creative Commons license

http://www.sciencedirect.com/science/article/pii/S1687404814000522


Building Barges Using Advanced Concrete Methods?
#222

Comparative Study of Geopolymer Paste Prepared from Different Activators
Debabrata Dutta , Suman Chakrabarty , Chandan Bose , Somnath Ghosh


(Wilfried Ellmer) #223

So what is the thread hypothesis - is geopolymer a perfect seasteading material ?..
Is it even a feasible large scale building material ?
How is it going to be combined to a composite material that works ?
Why it is not used already ?
Why not go with the “proven concrete engineering path” ?..