First off, an apology for not finishing the geopolymer experiments past the first round. I ended up moving from Florida back to California, things got packed, and then other priorities stepped in front.
Starting to look at it again, I did my usual “what has been done” look about. Also, being a bit more video oriented now, bothered to look at YouTube. Turns out the Geopolymer Institute has a youtube channel AND has shown just how to DIY and make your own limestone or harder artificial stones from natural materials.
I ran into these in reverse order. The newer video (March 2019) on Tiawanaku and hard “volcanic” stones first, the limestone second. As the pyramid limestone is the older video (12 years ago!), I’m going to present it first.
In it, they use old disaggregated (rotted) limestone rubble as their major material at 95% of solids. The binder is made from a mixture of kaolin clay, natron (sodium carbonate aka washing soda) and lime in water. The natural limestone in Egypt contains the kaolin already, but their source in the video didn’t have it, so it was added. Natron is found in the Egyptian desert, and lime is made by burning limestone. All inside the Egyptian technical wheelhouse.
The water (12-17% of solid volume), natron, clay and lime are mixed in a large tub, then the limestone aggregate is added. As a damp squishable material like wet beach sand, it is dumped in layers into a wooden mold and tamped. In 4 hours it sets up and in a few days it is fully hardened. It looks like real limestone.
A very quick under 5 minute demonstration:
Definitely a DIY backyard amenable process. Most folks don’t realize that native stone, exposed to weather, has a long slow “rotting” process that turns it into a kind of stone rubble. Eventually the end point of sand and clay is reached. At the base of many exposed rocky areas you can find piles of the stuff. Not everywhere, but common near exposed rocks of some age in places where it doesn’t end up covered in plants. In another source, Davidovits points out that the weak limestone of below the Sphinx in the quarry will disaggregate on standing in water for 24 hours. He proposes that is what they did (as it is too soft for building and much softer than the pyramid blocks). Turn the soft marl into aggregate then back into harder stone blocks.
From that wiki:
Marl or marlstone is a calcium carbonate or lime-rich mud or mudstone which contains variable amounts of clays and silt. The dominant carbonate mineral in most marls is calcite, but other carbonate minerals such as aragonite, dolomite, and siderite may be present. Marl was originally an old term loosely applied to a variety of materials, most of which occur as loose, earthy deposits consisting chiefly of an intimate mixture of clay and calcium carbonate, formed under freshwater conditions;
The Egyptians did know their mud ;-) Having two of the ingredients already mixed and the third in piles in the desert, all that is missing is lime. Use a chunk of limestone for a fire pit liner and you will form that. Now all that is needed is to pitch some of this stuff on a trash heap / ash pile and have it get wet. And observe…
So, pyramids done, how about those Space Aliens in South America? Seriously, though, why is it any unexplained constructed thing, the “Go To” answer is Space Aliens or a Pan-Global High Tech Lost Culture. Can’t it just be they knew a little chemical trick we’ve forgotten?
In this one, the technology used to unravel the source of material is much more advanced. Scanning Electron Microscopes (SEM) and X-ray spectrometer (EDS) analysis of minor specs in the rocks. Using this, they trace the origin of the rubble used to a particular site. There is a red “sandstone” and a harder “volcanic” andesite. For the harder “volcanic” stones, they have not yet had permission to test the likely source volcano just over the border in Peru, but do find that the use of phosphate causes the proposed mixture to precipitate to stone. But where to get phosphate? How about a guano island?
Then they show the historic shipment routes of the guano, and upon mass spec. analysis of the inclusions in the “volcanic” stone, find organic bits and the same elemental signature as the source guano. Pretty much nails it down.
The sandstone is made fairly simply with an alkaline binder and the andesite in a more complicated way with an acidic binder.
Rotted stone (sand / clay mix), Natron (Sodium Carbonate / washing soda), water.
His accent is a bit thick and my ears not so good, but I think he called it weathered sandstone and clay. (Also note he pronounces llama properly as YaMa…) As sandstone is a mix of quartz, feldspar and clay bits, and those are in just about all rocks in various degrees, this technique ought to generalize to several kinds of source materials. Even rotted granite has similar basic materials in it, you just need to make up whatever is missing to the “right” degree.
Note that when he talks about albite, it is a Sodium Aluminum silicate, likely formed from the sodium polysilate in the mixture when first made. https://en.wikipedia.org/wiki/Albite
Unknown volcanic rubble, water, organic carboxylic acid (vinegar or oxalic or similar carboxylic acids) then neutralized with phosphate / guano. As you can buy both vinegar and oxalic acid by the gallon these days and phosphate is as close as the garden store, this, too, becomes a simple DIY at home technique. Many folks have explored the native legend of using plants to soften stones, and succeeded at making the stone into mush, but then could not harden it again. They key bit there is the phosphate.
My speculation on the “tube drill” holes in Egypt (where they have spiral cuts in hard stone that would require diamond drills and tons force with current tools) is that they simply used an organic carboxylic acid to make the stone softer and as a lube while they did the cutting. Davidovits (who knows far more about this than I do) says this only works to dissolve limestone, so it may require a different material as the softening agent, or maybe it still softens ‘just enough’ for a hard tipped drill).
A VERY detailed scientific analysis of the entire local geology, potential source sites, microscopic, spectrographic and SEM analysis of it all and more.
1 hour+ a minute:
As I’d often said I thought the stones looked like they were cast, not carved, I’m happy.
Think if maybe we used stone bowls and pestles and cups and all for processing and cooking our plants, we might have noticed a long time ago that they softened under carboxylic acid mixes? Note that Citric Acid is one of this class. We can now buy it in small bottles in the canning department of stores (where folks still do canning…). So what happens when some “primitive” housewife complains to her stone working husband that his pestle isn’t so good as it wears very quickly when making orange juice? Hmmmm? Or maybe she just figured out to use the softened end bits to make some pretty beads with easy to form holes in them and then hubby asked “Hey, how’d you do that!?”…
Never underestimate the power of simple observation over long periods of time. I don’t care much how smart or educated someone is; it is far more valuable that they are a keen and objective OBSERVER. Nature gives us a thousand “experiments” a day, all we need to do is observe well and consider.
So now, armed with a much better theoretical foundation, I can set about trying to make my own small bit of geopolymer and maybe catch up to where the state of the art was 30 years ago (or 3000 years ago…) For “only” $130 you can get his book on how the chemistry works…
So I think I’ll be using the old trial and error and internet approach instead…