CONCRETE blocks/cinder blocks. It is basically just removing air voids (mild pressure plus vibrations) so the chemical bond of the cement can make the strength.
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It looks to me there is a minimal amount of water in the mix, just enough to activate the lime. If it was dry there should be dust floating about when dumped into the form.
The form has a vibrating device either on the back side or inside one of the tubes. The vibrator is foot activated. Just as he begins to press down at 0:46 his right foot moves just a bit and the little hook on the far side of the form moves. When lifting the form the user activates the vibrator with his right finger to facilitate separation and removal. Combined with compression added by the user the material would pack tightly with no voids.
If the block is 8" x 16" and the central posts are 2" in diameter, the area being compressed would be about 118 square inches. When pushing down the guy is putting much of his weight into it, perhaps 118 pounds of force, this equates to 1 pound per square inch. Not a whole lot, but the vibration makes the material flow freely.
Give the block a few days to cure, I suspect it will hold up for many years.
A rig could be produced at home with off the shelf components. The inside of the form would do well with a smooth surface. PVC pipe for the tubes. Something to create a vibration-an orbital sander or jigsaw would probably work. After that, get the concrete recipe right.
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For all reading this thread, please note that this is an older video and much has happened since its creation. There is a huge push within the rather insidious global concrete industry to promote, even at the grass roots level, OPC based systems. Most of these are modern portland based amalgamation are not (not at all) better than traditional earth based systems of CEB (compressed earth block.) I have worked with, and studied these different systems for decades now, and some are very promising while others are just a way to "pretend" to jump on the "natural build" band wagon. Geopolymeres and the budding "green" industries behind this is one of the more positive offshoots of the OPC industries. The OPC industry at large is receiving great pressure from society to compete with the "more natural" trends in the building industry. Tectonicly stabilized form work (as seen in the video) is one of the many systems being studied with earth and lime matrix, geopolymeric formulas, and the related.
I really like that folks are "studying" the many bits and pieces on the wed... Do understand that over 80% or more of it is either highly experimental (very unproven) and/or not coming from experienced or credible sources with proven track records. Also remember if it is coming from a "Contractors" or "manufacture" they have no reason to show a products short comings.
Please apply "Caveat Emptor" to everything you read/see on the web...
These blocks would be produced in backyard or workshop settings without ideal conditions. With limited controls, I think these homemade blocks would not have the same tolerances, strengths and longevity. Blocks produced commercially, in optimum controlled conditions, last for decades. Concrete is tough stuff. Environmental conditions and how it is used will impact the longevity of the block. Freezing and thawing conditions can have the greatest impact, all you need is a small crack which water can get into and disintegration can start.
My father poured some concrete steps in the mid 70s. They are still there today holding up fine. They'll probably be there another 50 years.
My uncle poured a short concrete wall around the same time. It cracked and fell apart in a few years.
These homemade blocks have many applications.
Would I use them to build a shelter for livestock? sure.
Would I use them to build a home which children would live in? perhaps not.
These blocks are a fabricated material. They need to be proven and tested before one can place faith in their integrity. If they are packed tight, made from a proven recipe, allowed to cure, and placed well, I think they could be used for simple construction. A tool shed, livestock shelter, and containment walls would fit the bill. Multi-story construction would demand proven materials.
Seed the Mind, Harvest Ideas.
Good points made by all. I have worked with concrete over the years on small projects, and seen a lot of backyard gardeners do their own thing. From what I have observed and what I have been told, there are 3 variables that will shorten concrete's life significantly. The first, not having the right amount of water in the mix combined with not mixing adequately. Second, not preparing a proper foundation for the project. The third, perhaps a bit distant third, not having the right curing time. In the past couple of decades, sealers have become an important part of the concrete picture - I am guessing rammed earth would also benefit from them as well, but if the foundation is not properly laid, the bricks will crack, and no sealer is going to prevent that from happening.
If I were to undertake such a project, I would certainly consult a PE to give me advice, recommend a soil/mineral mix and give me useful skills to test the mix with, and would also contract out some testing of sample blocks. I have access to free/very cheap equipment rental through friends, so I would be using a big cement mixer to prepare the soil to obtain a very uniform standard.
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