All the answers and much more, can be found on Davidovits website Geopolymer Institute
It is highly technical chemistry discussion but I will try to generally address the questions.
There is always extreme danger of one amateur, relaying information to another, but:
Open mind Wrote:
> Corpuscles Wrote:
> "Note the only andesite is in the renovated back
> fill. The structure is essentially reconstituted
> limestone, so no igneous component, derr….
> despite dipstick comments in the thread."
> I have had a hard time keeping straight which rock
> is which in the various sites around the world. I
> had thought for the longest time that Sacsayhuaman
> was igneous. And it was a nice convenient way to
> perceive the work simplistically segmented into
> pillow stones = igneous. Then you can
> oversimplify the 'magic' to being a material
> manipulation of the crystal structure totally
> uniformly, where as in limestone, if you only
> manipulate the crystalline content of that rock,
> then it will look different, like the core blocks
> of GP.
> But its not that simple clearly.
One of the big problems in "mysteries" around the world is that the stone is often inadvertently incorrectly identified.
> Limestone is formed by pressure. And you can't
> melt it and reform it to appear the same like
> igneous might be able to. But to reconstitute it
> back into typical limestone hardness, you need to
> simulate that pressure somehow. Or, as the
> geopolymer theory suggests, that hardness is
> entirely based on the properties of the binder. A
> 'magic' binder of sorts, that survives thousands
> of years, so we're all vulnerable to the WOO
> moniker, to be fair.
Limestone is not entirely a product of pressure (some yes). In nature further up the family tree it becomes more important or critical (marble) but harder forms (such as Dolomite) is a function of whether traces of alkali metals are present in the sea water especially a magnesium compound.
Natural stone has its own small percentage of naturally formed binder. Geopolymer and some Alkali Activated Materials (AAM) merely mimic nature. However modern man has incorporated other irrelevant stuff in modern science like blast furnace slag (to find a reuse for it)
As for long lasting. I think you are in USA? There is no man made concrete over 300 years old there? Yet you have likely seen many old building sites where concrete has perished, crumbled decayed with concrete cancer or weathering etc?
On the other hand Roman concrete (based on a mimic of nature formula) is still going strong 2000 years later.
> So I guess my next big question to the geopolymer
> camp is this: Are you proposing that the ancients
> invented a compound from available sources that
> cures so hard as to simulate the hardness of
> natural rock, which by far outperforms most
> typical modern day concrete, even with the
> advantage of steel bar reinforcement inside?
In geopolymer the component of the binder is generally about 3% to max 7% of the stone.
Davidovits has several vids or papers showing the comparative strength attributes.
Compressive strength is roughly equivalent., because it is the natural aggregate or stone that provides that. The steel reinforcement largely is there to provide some tensile strength.
If your driveway at your house was extremely professionally done, it will have a hardness of circa 40 MPA. If you have hand mixed a path or such likely circa 20 MPA max.
Davidovits standard for limestone based geopolymer concrete is 90 MPA and he claims they have achieved 150 MPA.
In slabs they still sometimes put in steel reinforcement but Geopolymer has extraordinary tensile strength already.
It is a polymer. A 3 dimensional molecular repeating chemical arrangement. Sometimes like helical DNA therefore "living stones"
> If I consider the possibility that we can, at
> present, duplicate that binder performance, then I
> have to assume the reason why it hasn't taken over
> the global industry is because its so cost
> preventative a process to make. And that
> potential high cost is either because of extremely
> expensive and complex advanced processing plants
> to produce it, OR, that its constituent material
> components are rare enough to make it very costly
> to find and extract in large enough volumes.
At present it is more expensive. However that is to do with volume more than ingredients.
Eventually it will take over Portland cement in many parts of the world. There is an Australian company (working closely with Davidovits) to address the Middle East / Mediterranean market. The climate and conditions are extremely harsh on concrete there they need something far more durable. (Think Dubai)
Also geopolymer is extremely fire resistant. Normal concrete explodes at approx. 200 C, geoploymer is not degraded at all till over 700 C
The hoohar over Global warming - geopolymer does not emit Co2 - One of mans main producers of Co2 is concrete.
> And that cost calculation is also presumably
> taking into account the significantly reduced
> amount of material necessary, (as it so thoroughly
> outperforms regular concrete 1:1), while used in
> conjunction with rebar to give it every advantage,
> to duplicate the present day concrete performance
> industry standards. So even having to use far
> less of this material, its still financially
I have not explored all the cost benefit stuff. I refer you to his website it is there in library of papers.
> If the answer to the above question is yes, then I
> have to assume you are open to the existence of a
> highly advanced ancient global civilization.
> Because building materials should be the spear tip
> of our best applications of the highest level of
> material science, and if we haven't even worked
> through the economies of scale to implement today,
> what they used all over the world in ancient
> times, then our present level of advancement pales
> in comparison.
You are touching on some areas which restricts many from accepting/ considering the possibility of geopolymer use by Ancients.
We think one needs a chemistry degree, a lab coat, an electron microscope, X ray and spectrographic analytic machine to do it. That is how it is done in 20th/ 21st Century.
But all it is doing is replicating and understanding what happens in nature.
The ancients … let me be hypothetical... (my fantasy not Davidovits endorsed)
Ancients see limestone is full of seashells. It is far away from the sea. They think how does this happen???? must have something to do with the sea. They go to a dried up salt water lake. They observe that some of the "stone" saturated in water is soft and malleable (has kaolinic clay combined ) They find natron, they find lots of looses shells they "give it a go" mix it all up make a block, like they did with mud and straw before, and eventually find the mix that like magic hardens to better or equivalent to the natural stone
Similar story for decomposed igneous volcanic ash, involving acids and bird guano (potassium)etc
They didn't have to be super civilized nor high tech , just very observant of nature.
All the ingredients were readily available in vast quantities no smashing up of rocks to powder was necessary.
I should stop there or I will rant on to book length! LOL! there is so much more to it than is covered by intrepid 'mystery' hunters