Delamination on geopolymer blocks in Peru

2024 Author: Seth Attwood | [email protected]. Last modified: 2023-12-16 15:55

Detachments in block rock have been observed in clutches at Cuzco and Ollantaytambo. The rock exfoliates from the surface, and does not delaminate horizontally, diagonally or at any other angles. There were no examples of rock delamination in the photographs - only thin surface layers fall off the blocks like shells.

Not only do the blocks have a convex shape, but this "shell" peels off from their surface, repeating the curvature of the surface. In rocks, the layers are usually arranged in horizontal layers. And when laying blocks cut from natural rocks, the builders tried to orient the block exactly horizontally - this is how the block has the greatest compressive strength. With a different arrangement of layers, it breaks down faster.

Arcuate detachments are not isolated. But not without exception in all blocks.

Delamination is very similar to plaster breakdown. But it has the same color and kind of the same breed as the block itself. These delaminations resemble local stresses in the rock, or rather, stresses and strains in the near-surface areas of blocks. And this may be the case - if the volume of the block in this place changes its size in the direction of increase.

I had previously posted article with versionexplanations of the reasons for the increase in the volume of trowant stones. In short, the reason may be hidden in the presence of bentonite clays in the composition of the rock. When moisture gets inside, the stone slowly, but still increases in size. Rock delamination also occurs on trovants. The same mechanism can be in the case of delamination on blocks of polygonal masonry.

My brief explanation (for those who are reading this article for the first time from a series about polygonal masonry construction technologies): the masonry was molded from plastic masses, geo-concrete (or, according to scientific research, cold fluidolites), which previously emerged from the bowels. Now the bowels are in relative calm and such phenomena do not occur, with rare exceptions, and then in the form of mud volcanoes.

The ancients saw that the rock turns to stone over time (probably on contact with CO2 in the air), first becoming covered with a crust. Because any rock is vapor-permeable, then stone formation also occurred inside, but more slowly. Due to the presence of a certain percentage of bentonite clays in the plastic rock, the stones in the masonry expanded, became convex and the seam between them practically disappeared.

When moisture falls into the pores of the block - if the inner mass has not yet completely petrified - it pressed on the outer layers. And those by that time had already turned into a solid breed, which exfoliated like a shell. In short, something like that.

Blocks of different shades. Perhaps there were several sources of geo-concrete.

This photo gave me another version. It is possible that the formwork in which these blocks were molded (in fact they were shields) was coated with something in the form of ordinary clay (for better separation from the blocks). This is what we do in industrial construction, when concreting buildings - we coat the formwork with a special lubricant.

There was a diffusion of the composition of this clay with geo-concrete to a certain depth. The rock changed its properties, decreased strength, and the thermal volumetric expansion of this layer changed. And with temperature drops, this layer began to peel off gradually. This surface layer even differs in color from the rock inside. It is more clayey.

This is one more proof in the piggy bank of the version about the technology of forming such masonry from natural geo-concrete.