I happened to be reading about bentonite clay for reasons unrelated to ancient history. I noticed that it expands with amazing force. It will double it's volume even under 10,000 psi of weight on it, according to the first article pdf I will reference later in this post. You simply take dry bentonite and let it absorb water and it expands dramatically. Here's one quote about it that gives some information on how it takes place. It involves electrical charge forces, not just absorbing water and equaling the sum of the volumes of the dry clay and the water. It expands more that that.
"Bentonite is noted for its affinity for water and for tremendous swelling properties. It can be described as a bundled plate structure, the surface of which is populated by sodium ions. The addition of water causes the sodium ion to hydrate, generating a negative charge on the bentonite plate. Since like electric charges repel each other the platelets are moved apart causing a phenomena called "swelling". The rate of swelling depends upon the fineness, grade and how the bentonite is handled. All grades expand very slowly when water is poured on them, much faster when they are poured into water. Fine powdered bentonite grades absorb water slowly; intermediate and specially sized bentonite absorbs water more rapidly.
Bentonite absorbs nearly five times its weight of water and at full saturation it occupies a volume of 12 to 15 times its dry bulk weight. On drying it shrinks to its original volume. Swelling is reversible - it can be (wetted), swelled and (dried), shrunk an infinite number of times if the water used is fairly pure. This swelling is important, since the entire swollen mass - that is clay and water behave as if they were clay." [www.canadianclay.com]
There's a pdf of an article available, though I don't have a link, entitled Swelling of Clay Under Pressure, by Paul G Nahin, which gives some data on the expansion under pressure. I found it through Google (quite a while ago actually, which is why I don't have a link) so I'm others could also. Another is The Swelling Pressure of Bentonite and Sand Mixtures, Sandra Sanchez Gonzales.
Point being, it would probably be possible to force large heavy stone blocks upward using that expansive force. I obvioulsy don't know exactly how that would be done, maybe just putting it under the stone and adding water, or letting moisture from humid air gradually absorb. I don't know if it would have to be contained from the sides to result in upward force, or if it would work just as a free mass. I haven't actually worked on this theory or anything, just figured that it might be a way of raising stones, bit by bit, adding supports as you go up. Maybe the ancients noticed natural clay deposits heaving up large boulders. Nobody seems to have had any other good ideas of how those massive megaliths were raised, so this one is as good a possibility as any. Bentonite would certainly have been available in most regions. From my reading it appears that the force is at least in the range of 1500 psi. So a square foot of it could theoretically raise about 100 tons. A square yard could therefore raise a 1000 ton megalith.
"Bentonite is noted for its affinity for water and for tremendous swelling properties. It can be described as a bundled plate structure, the surface of which is populated by sodium ions. The addition of water causes the sodium ion to hydrate, generating a negative charge on the bentonite plate. Since like electric charges repel each other the platelets are moved apart causing a phenomena called "swelling". The rate of swelling depends upon the fineness, grade and how the bentonite is handled. All grades expand very slowly when water is poured on them, much faster when they are poured into water. Fine powdered bentonite grades absorb water slowly; intermediate and specially sized bentonite absorbs water more rapidly.
Bentonite absorbs nearly five times its weight of water and at full saturation it occupies a volume of 12 to 15 times its dry bulk weight. On drying it shrinks to its original volume. Swelling is reversible - it can be (wetted), swelled and (dried), shrunk an infinite number of times if the water used is fairly pure. This swelling is important, since the entire swollen mass - that is clay and water behave as if they were clay." [www.canadianclay.com]
There's a pdf of an article available, though I don't have a link, entitled Swelling of Clay Under Pressure, by Paul G Nahin, which gives some data on the expansion under pressure. I found it through Google (quite a while ago actually, which is why I don't have a link) so I'm others could also. Another is The Swelling Pressure of Bentonite and Sand Mixtures, Sandra Sanchez Gonzales.
Point being, it would probably be possible to force large heavy stone blocks upward using that expansive force. I obvioulsy don't know exactly how that would be done, maybe just putting it under the stone and adding water, or letting moisture from humid air gradually absorb. I don't know if it would have to be contained from the sides to result in upward force, or if it would work just as a free mass. I haven't actually worked on this theory or anything, just figured that it might be a way of raising stones, bit by bit, adding supports as you go up. Maybe the ancients noticed natural clay deposits heaving up large boulders. Nobody seems to have had any other good ideas of how those massive megaliths were raised, so this one is as good a possibility as any. Bentonite would certainly have been available in most regions. From my reading it appears that the force is at least in the range of 1500 psi. So a square foot of it could theoretically raise about 100 tons. A square yard could therefore raise a 1000 ton megalith.