Compressed earth block - Multiple questions

I have several questions about this topic. I hope they don't get lost in the conversation.

In northern NY we have a yearly average temperature of 40-45 degrees F. Average relative humidity is 68-72% with highs ranging from 72-87% in the mornings. (taken from City-data.com We wanted a structure that would be slow to change temperatures and be able to breathe naturally.

What kind of weight are we going to need to support?

Our exterior walls will be double walls constructed with compressed earth brick with an insulating cavity between the exterior and interior wall. All buildings are single story of approximately 10 feet. Assuming a compressed weight of 100 lb/ft3, that equates to 0.058 lb/in3. Now, multiply that by 120 inches (10 feet) and we arrive at 7 lb/in2 on the bottom of the bottom brick (grade beam). That doesn't seem like much, but we have to add the weight of the roof. On a conventional building, the lateral walls support most of the weight of the roof as the end walls do not normally support much of the weight. Also, for the sake of keeping figures simple, let us assume no interior walls are supporting the weight of roof. Our buildings will be 36' x 20' and roof pitch of 6/12. There is 50% more roof area than floor space. We add 2 feet of eve for each side and end to result in a roof area of 38' x 34'. We are in upstate NY where snow load is 55 lb/ft2. We desire a sedum roof so I will add 10 lb/ft2 for a total of 65 lb/ft2. 38' x 34' = 1292 ft2 x 65 = 83,980 lb.  Divide that by 2 to get weight supported by one wall. 83,980/2 = 41,990 lb. Divide that by the wall length in inches 41,990 / 408  (34' x 12) = 103 lb. Since this is shared by two 6" walls, divide that by 12. 103 / 12 = 8.6 lb/in2. Add this to the weight of the wall (7 lb/in2) and we arrive at a 15.6 lb/in2 for a value at the surface of the grade beam.

Am I good so far?

The exterior walls will be protected from rain splash up to 36" from the ground by field stone wall. There will be a lime plaster applied to the walls inside and out.

Now, for the making of the compressed earth bricks...

We have a retired sander body from a snow plow to use as a hopper. The chain that was used to dispense sand and salt will be used to convey our earthen mixture to a mini-hopper for mixing. It will then be loaded into the form to be compressed. Upon ejection from the press, the side of the brick will be scored to better hold a lime plaster.  We had the intention to ravage our 40 ton wood splitter as a base for our press. I have reservations about the size of the brick and the orientation of the compression of each.

12" x 6" x 6" brick gives 1,111 psi (12" x 6" side) and  2,222 psi (6" x 6" end).
12" x 6" x 4" press results in 1,667 psi (12" x 4" side) and 3,333 psi (4" x 6" end).

I tend to believe the smaller surface area press to be superior as it give a higher compression pressure. End pressures are highest, but I do not have the experience to know if the pressures are applied thoroughly throughout the brick, leaving the area opposite the moving foot/plate with an incomplete press. Has anyone compressed bricks from the small end with success?

All of which result in a compression that is at least 17 times the weight the bricks will be subjected to. I do not question the bricks ability to handle the weight when constructed. I do, though have reservations about the longevity. Moisture will be a BIG factor. in their ability to hold up over time. Will a lime plaster keep enough moisture out of the bricks to keep them from disintegrating? The bricks will be scored/scratched on one side as they come off the press to give the lime plaster a good surface to adhere to. Will scoring be enough to ensure proper adhesion of the plaster to the brick?

I know most of you are asking yourselves, "why aren't you mentioning stabilization?". Well, that's another question I have, Actually, I have a couple questions about that. I have seen CEB wall failures on the internet. They were all where the walls had penetrations where water was actively running into the wall from leaking pipes, either pressurized or drain. I do not know if they were CSEB (Compressed Stabilized Earth Brick) or CEB style or brick, but we have no wall penetrations intended carry water, or air for that matter. So, I still wonder if stabilization is necessary? I think it is a good safety measure. But my most pressing question on stabilizing bricks is when to place the bricks in the wall. It is very labor intensive to take the bricks off the press, place them on a (pallet) and place them in a location to be cured. Then bring them back to the building site for placement. I understand cement-based stabilized brick needing to be stored close to each other and covered (even kept damp) to cure. But would even lime stabilized CEB need the higher moisture storage to cure properly? Isn't lime plaster cured on the wall? Would the curing of the lime plaster on the lime stabilized CEB not bond them together ensuring the would need less maintenance? Also, what types of fibers would accentuate the strength of the plaster? We do have straw available as we intended to build with it but have since changed our minds.

I am not afraid of work, but I am curious if anyone has experience or input that I have not thought of. I have a very small crew including myself and my wife. Hopefully friends who are curious will be of assistance at least for a day.

Doors and windows are of concern for water penetration. They are always a concern, no matter the construction method. Do you have any advice on how to avoid issues with those as I have not found much on those subjects. Primarily because I spend so much time on materials, plans, excavation, building tools and equipment...etc,

Thank you.

Forgetting to include data in posts seems to be my specialty.

I also have to add that I have another question. Is there anything wrong with not stabilizing the interior section of the two wall system? This would cut the use of lime (5% mix) in half from 16 ton to 8 ton for a 34' x 20' dual wall exterior. Also, every "Nth" course chicken wire will be laid over the tops of the bricks to tie the inside and outside walls together. Perhaps a second, larger press mould could be made to have a larger block used to tie the two walls together? I have read that a bond beam is advised every "Nth" course, though I don't remember where that was mentioned.

There will be at least one interior wall tied/meshed with the interior exterior wall on the long sides of the rectangular building to keep lateral forces on the walls in check. Our house is designed to be a round building, again, with the dual wall system. Being round it is arched and therefore, very resistant to lateral forces.

I'm sure I have more data and questions. More to come.

You have far too much detail to find the questions and the information.
Mathmatics is usually set out so the equation can be seen by itself.
Could you consider rewriting the mathmatics, and pulling out the questions as line points please?

I can see how it could be too much information. I, most likely, have had much longer time to think about this than others here. Let's try this one at a time.

Building two walls with an insulating cavity between them, can I leave the lime stabilization out of the CEB mixture since it will not be exposed to the wind and rain of the exterior?

The lime is the stuff that helps hold the earth together. eave it out and the blocks may dry to sand like granules

Drying out could also change how solid the walls are if put in place to dry. I realize now, that depending on the shrinkage, gaps most likely appear between the bricks where there were none. Gaps aren't something I may care about as far as vertical strength, but it is the lime plaster I was thinking of placing on the brick before the blocks were dry/cured. The shrinking will cause problems with the plaster. Cracking it much more than it normally would. These cracks will allow water into the wall. Definitely not something I want.

I know there are steps in a process and they are usually done for very valid reasons. I would like to know the reasons. The more people I talk to and videos I watch, I slowly gain the knowledge of why certain steps have come to be and that shortcuts aren't conducive to quality finished products. Knowledge is king!

I would check out the open source earth block press if you have not already.

They have built homes with this and have real world data for results.

[youtube]
https://wiki.opensourceecology.org/wiki/CEB_Press[/youtube]

Now, for the pressing of the bricks.

Compression

Is there a preferred method? Meaning from which face of the brick? We want a brick that has the highest compression strength we can make. Considering the same force, the highest compression is a result of pressing against the smallest area, which is usually the end of a brick. But I am thinking something might be amiss with that idea. The end/side furthest from the hydraulic ram will be the least compressed since the soil will be forced toward the outside walls of the form and into the lateral points of the form. This reduces the pressure carried through to the furthest brick face.

-------------------------------
|------+-+-+-+-+++++++|
|------+-+-+-+-+++++++|  <---------- FORCE
|------+-+-+-+-+++++++|
-------------------------------

----------------
|--+-+-++++|
|--+-+-++++|
|--+-+-++++|
|--+-+-++++|  <---------- FORCE
|--+-+-++++|
|--+-+-++++|
|--+-+-++++|
----------------

Has anyone tried compressing from opposing sides to help maximize compression throughout the brick?

                            ------------------
                            |++++--++++|
                            |++++--++++|
                            |++++--++++|
FORCE ----------> |++++--++++|  <---------- FORCE
                            |++++--++++|
                            |++++--++++|
                            |++++--++++|
                            ------------------

Shrinkage

I understand clay shrinking. Considering a damp mixture, a 20-30% clay content would normally shrink 70-80% less than 100% clay, correct? Lime changes the clay at a molecular level? Two bricks the same dimensions and moisture level, will a lime stabilized brick shrink as much as a brick that is not stabilized?

Making CEB
You will make one brick at a time!
- avoid expansive clay it cracks badly
- moisture content is determined on the day. It needs to be squeezed in hand and not ooze like toothpaste
- make test bricks
- if using an hydraulic press allow 20% wastage because it takes time to ensure moisture content is correct and some get through with low MC.

Ways to make a CEB
Adobe or mudbrick, the most common method used world wide.
Sloppy mud pushed into forms and air / sun dried.
Adobe
Hand operated press
Dalrac, Cinva and others
Uses a drier mix and can be handled quickly
Hand press 3rd world
Hydraulic pressed using a power operated machine.
Works very quickly but some are too dry and break up over time.
Civa Ram or similar to a Dalrac Press

Yes, we will be using a hydraulic press. Please, allow me to me give a quick-over of our process so far. Please forgive my imperial measurements as we foolishly have not made the switch to metric.

I-beams and a set of tandem axles to put our machine on so it can be moved where it is needed.

I built a shaker/sifter to separate soil from rocks bigger than 3/8". Some 1/2" slender rocks do get through. I could go smaller screen, but I think this will be fine enough. This does a great job breaking up soil as well so that if flows very nicely...even after a winter sitting uncovered. This can process about 2+ yard of our soil per minute if I could get separated rocks away and unprocessed soil to it with enough speed.

The sifted product is moved by tractor into a 12 foot long, 4 yard hopper that, at its bottom, has a variable speed hydraulically driven ~16" wide chain. I believe this to be design that will ensure a proper soil flow. The hopper also has a variable aperture to aid in controlling the output. This will empty at a rate from zero to over a ton per minute.

This is as far as I have progressed.

I am at the point now that I need to design and build the press, but I want to be sure I am building, not the best press, but a press that will make the best brick. After all, it is the brick that will tell its story over time. Once the press is made, it will be placed in its position on a trailer.

We have a hydraulic wood splitter we can disassemble to make the press. It pumps 25 gallons per minute at 3,800 psi. It cycles its 24" cylinder's 78,000 lbs of force every 9.5 seconds. This will make a wonderful candidate for our press.

We own a 4 spool electrically actuated hydraulic valve/manifold assembly. Each output port can be manually adjusted for proper flow rate when actuated. I am able to build and program a controller for the unit's control, though i have never used limit or proximity switches. How hard can they be? IF AND OR ELSE DO WHILE ...

Somewhere along the process I need to mix water and lime in the soil fines. I'm not quite sure where they are going to occur. Moisture will even itself out (somewhat) within the brick, but lime will not. The lime must be mixed in thoroughly for a proper brick. I'm unsure it should be done in bulk in a mixing tank or by brick-by-brick batch in say....a 30lb mixing drum just prior to going into the press.

With 30,000 bricks for one building (I have 4 to build), I don't want to have 20% waste. If I could break the defective brick up and put them back through the process I could live with the minimal material recycling.

Experience of others is greatly appreciated.

And thank you, John, for hanging in there with me and my post.

HAHAHA, we are stuck with each other, I am an earth block guru!

Moisture will even itself out (somewhat) within the brick, but lime will not. The lime must be mixed in thoroughly for a proper brick. I'm unsure it should be done in bulk in a mixing tank or by brick-by-brick batch in say....a 30lb mixing drum just prior to going into the press.

Moisture within a block will not even itself out!
Lime and moisture must be evenly mixed through the raw material, because both components react on
the clay particles nearby and cause the granules to stick together creating a block that will not fall apart.
I have found getting the raw soil to an ok moisture content is best done in a large pile, and spraying with water,
rain etc until its completely soaked and then covering it, is the best way to have everything damp.
With no dry bits anywhere in the pile.[ weak points]
Then batch mixing in the lime and then using the brew.
BREAKING UP DUD BRICKS
That is the way hand pressed bricks have quality control.
If you cannot handle the block as soon as it comes off the press, break it up and check moisture content or volume of soil.
PRESSURE TO APPLY
As for what pressure is best, just enough to push enough particles to gether for the osmosis that takes place between particles and the moisture present.
If you use high pressure the blocks may look and feel good, but they will dry to a pile of granules over say, 3 years.
Test batches and check are the best way to do things right.

I'm glad i can communicate with someone who has done this before. Especially someone who has tried multiple ways of making bricks. I would have tended to measure individual brick material moisture and added water as needed. Mostly because I am maybe a micro kind of person and do not always see the bigger picture at times. Or...I just thought of this first. Measuring, mixing and controlling the moisture on a large amount of soil may seem like it is too large of a task to maintain moisture and properly mix the water and lime.

I can make things to measure, mix and dispense at proper levels in smaller batches. Something where I can add bulk materials and automatically dispense and mix before pressing. To me, this is the way to ensure a good brick. Though, admittedly, I have never made a earthen brick with anything other than a homemade Cinva ram. I also know nothing is perfect and there will always be something in the process to hold up production. I also know all too well, that I do not know everything and must accept advice from others who have experience. After all, that is why I am here. So, bulk mixing it is...luckily I have a rototiller for my tractor to help with the mixing of lime and water as needed. Maybe mix up in the morning what is required for the rest of the day. Please, excuse the math. 25lb brick x 6 bricks/min x 60 minutes x 6 hours = 54,000 lb /100 lb/ft3 = 540 yd to mix for the day? Ya know...maybe I was better off if I didn't know that. Maybe I'll start small and work up to a comfortable batch. I tend to get ahead of myself and get overwhelmed. Overwhelmed = bad. Fun/Comfortable = Good! If we don't have a building dried in this year, it isn't like we are going to be in the cold. We still have our current shelter that has been cozy for a while now. We aren't fighting with each other because quarters are too close...yet. My trouble will come when I try to pick up the mixture with the loader. I tend to dig too deep with the bucket and would most likely get unmixed soil and lots of it.

I know I have 4 different usable soils on our property but they are all pretty similar. Only two of which I have considered making bricks with, though all could be used if there is a situation where the mixing of soils would be required. But I have not checked moisture levels. Mostly because I know the levels will change by the time I am ready to start making bricks. A neighbor grows produce for his market. He has started watering daily. Water levels will drop considerably over the summer, drying my property and draining my well. I do not wish to strip the topsoil until I am ready to start producing so i do not lose moisture. We are planning to cover our bricks with tarps until they have cured. While they cure, we will put buried utilities in place and prepare the foundation(s).

I do wonder how to place the curing bricks. Most likely I should store them on pallets so I can move them to where they will be used. Is there a specific type of tarp material? Or can they be covered with 6 mil poly sheetingas it is much cheaper than tarps? Does heat affect the curing? Black cover vs clear will determine how much heat will be created under the cover material. Can the bricks be stored on the ground, on the ground on pallets? Summer max temperatures have been 90-92 (seems much hotter) with night time being 70-72. Covering the bricks will boost these temps greatly. I have heard of "Flashing" lime mortars if temperatures are high.

Also, I am concerned about wear in the press mold. I have 1" plate material to make the mold strong, but I am concerned about wear. If there will be considerable wear for the amount of bricks I will be making, I want to make room for a thinner replaceable wear plates on the surfaces so I do not need to rebuild my mold. With all of the building I expect to do over the next couple of years, I suspect about 200,000 bricks will be made. I have not seen numbers like this and wear being mentioned. What type of wear plate material should I be looking for and what thickness? How much wear should I expect to see before I need to replace these sacrificial plates?

Still rambling with your entry.
But I have read it all.
I am a Civil Engineer and like clear concise notes, but lets try and keep it happening.
My view is that no task is too big.
I do not allow myself to be overwhelmed, I break it down to smaller tasks that are manageable, and I line the tasks up in a row based on what needs to be done first etc.
We call it critical path analysis, some call it project management.

By example I am now 72 years young, have bought up a grand daughter since she was 3yo and is now 19.
I ran 3 retail businesses, a small farm and raced and maintained road racing sidecars.
Today I run a repair business, a welding business and still have the grand daughter and still race etc.
I do not allow other peoples opinions on being busy or not to concern me.
It takes a mind set to just keep moving, I waste time reading papers, watching TV and doodling in my ideas book. I spend time with friends so I am not a hermit.
BUT I am always thinking and planning how to do things better.
SERMON OVER
STEPS TO COMPLETE HOUSE
1 Have a toilet and a hot water shower
2 have a bench to prepare, cook and eat food from. With chairs for everybody
3 Keep mozzies and bauds away
4 Have good and easy water supply
5 have shade
6 take time out to chill
ACTUAL TECHNICAL STUFF
- Soil needs to sit and soak up the water with the soaking, that takes time
- Bricks can be left exposed to the atmosphere except if its raining
- dont rely on working bees
- expect about 100-200 bricks a day
- stack on pallets and move to where they will be used.
- Mix soil and water in a hole with the rota thing and leave to 'cook up'.
- lift out enough soil for the day or at least not too much that it dries during the day and mix in the lime
- make bricks and stack 2 or 3 high with air space everywhere. Slats of wood between layers.
- allow about a month to dry
- Drink beer each day for hydration only.
PLAN AHEAD
- I believe its best to construct a steel roof structure with steel poles which will form part of the completed house for shade, shelter and water catchment
- pour footings for all the walls needed for the first stage
- Drink beer for hydration purposes only
- As you collect building materials stack them under cover neat their ultimate location
- store bricks close to where you will use them
- Mix up brick making and brick laying times so you see progress.
- Drink beer for hydration purposes only.
- Allow a couple of years to complete the house.

Sorry Mart, I should have acknowledged your post. Yes, I have seen the videos. Many of them from many different press makers. Of course, they show the machine working flawlessly, or near perfect. I look for what would make my life very difficult so I can design for eliminating the difficulties I find. There aren't many videos that I have found of people who have purchased one of these machines and having the machine in use. I did find one video of a man and maybe his son who had purchased a hydraulic CEB machine. They were having a heck of a time, mostly with the soil not flowing. I felt bad for them, they had all new equipment and were frustrated. But I think that was a case of not knowing their soil, its properties and inexperience. They had money to buy expensive tools and equipment, but had not thoroughly studied the process or their raw materials. Unbiased videos are a great way to expand knowledge. Especially if you are not an abstract thinker but can be quite observant.

The vertical press is not feasible with what I am doing because my hydraulic cylinder taken from my wood splitter is too long. If i am to build my press on a trailer, the whole machine will be too tall or the bottom of the cylinder will be below the ground surface. I plan to build a horizontal press. Hopefully, I can place a likeness of the finished design and a few pictures of what I have and the process.

I talk to people and they say they are busy or busier then ever, but it is nearly impossible to see any change in their life. It is not for me to judge and I don't, usually. I understand that progress can be hard to see. Especially when one person is researching, imagining a tool or tweaking another design, building the tools to assist and assembling the final product (Which many times is never final, but is forever being adjusted). This process isn't always obvious to the outsider. But it isn't usually about the outsider? Their environment is their own and I can hope they are happy in it. But when they are in need they can look elsewhere for knowledge and thought provoking guidance. I hope that insight comes from a happy, healthy and well-meaning source. The more important that guidance is in the individual's life/environment, I would hope that person should find a variety sources for the knowledge sought and make decisions based on information attained.

I'm not directing this ramble toward anyone in particular. I watched Pelican Brief last night with my wife and I am still affected by it. I'm not going to get political or into any ideologies. I just know that my own thoughts and ideas may not be the best for everyone. Or even myself, for that matter.

I guess I'm done with this post. I type and delete, type and delete, type and delete..... I cannot continue without it reading like I'm being political or ideological.

I will return with images of goals and progress of hydraulic CEB machine.

My shaker/rock separator/sifter. Made from scraps around here and some metal pallet shelving supports. It has a 7HP gasoline engine. Currently has a worm gear drive from a snow blower auger/blower. I think I will be changing the drive system to a multiple pulley system for less wear as I think the worm gear drive is too light for the motion when loaded with soil. The engine is plenty strong enough even at half throttle and shaking at about 2-3 4" strokes/second. I can load about 1/2 yard at a time from my tractor with a 7' wide bucket. Expanded metal is used as a screen. I built it just wide enough to get the tractor bucket under the shaker. I should have made it a foot wider as I sometimes hit the sides and move the shaker when I get in a hurry and am not so careful. Still, it works well for having little invested. We cannot see spending $9,000 for a soil sifter.

I bought a slide-in sander at auction. At the time, I was intending to use the hydraulic chain drive as a log feeder of a firewood processor which would move a log to the proper place to be cut. Since then, I decided to build a automatic hydraulic compressed earth brick machine. I think it will work well and will not have an issue with plugging or bridging.

I am concerned its not big enough for the task???
Have you tried shifting clayey material with it?
I think it may not work efficiently.

John,

Not large enough? You are being sarcastic, surely.

Soil sifter: If I can load it fast enough I think I can sift 2 yards of soil per minute

CEB hopper: It holds about 4 yards of soil.

I have not sifted wet or moist soil in the sifter. Only damp and dry. We do not get enough rain during the summer to be a concern for sifting. At most, I would be put off by a couple days.

You have reminded me, though, I need to gather soil samples from a few places about the property.

We have a spot below where we are building that I wish to have a pond. Our foundations drain to this area.

Another would be up high, close to our small orchard where it seems to stay wet the longest in the spring. It would be out front of our house and would make a lovely spot to watch ducks and geese. And turtles. I cannot forget turtles. My wife loves them.

If we need to add sand, perhaps at the bottom of the field that contains the orchard has plenty of sand. It seems it is never wet there. Even after a big rain and the water flows down the hill

Also, John, what may not work efficiently? The sifter or the hopper I plan to use for the CEB press?

I was saying it with my tounge in my cheek!
The Hopper, is my concern, with the moisture content required I thought a screw feeder would be best.
BUT, an experiment may prove that theory incorrect.

John,

I thought you were kidding about not being big enough. It is difficult to distinguish between a jest and a proper inquiry over the internet when we cannot see facial or body expression and hear inflections in the voice. So, better to ask. :-)

I kind of agree with you on the chain not being the best choice, but at 10% moisture, the freshly sifted soil should flow fine. Time will tell. I'm crossing my fingers. If it doesn't work, I still have a decent log feeder for a firewood processor. I have another hydraulic motor to drive an auger and unfortunately there are plenty of defunct farms about and I should be able to find an old feed auger for a reasonable price for adapting.

I'm going out now to get my soil samples.

Got the samples all samples were obtained after removing two feet of soul to get below the topsoil and organics. They have been sifted, leaving the pebbles in the sample as I will use the soil in production.

I talked to the brother of the previous owner about a location for a pond. As a vegetable producer, he pays attention to soil and water. He stated that the soil at the top of the property would be the best place for a pond as it appears to have water for the longest duration of the year. It may need to be sealed with bentonite if dug there. Our well is about 400' north and 5' below this spot and I tend to agree with him as we have seen 3 out of 5 years we have owned this property that the water table is at or above ground level. When I dug in a water line from the well, it appeared to have a lot of sand down to at least 5' sub-grade. Why not put a pond there, you say? It is my well, and I also do not want water to follow the water line trench to saturate the soil and foundation below my house.

SS1) At top of orchard field - holds water or is wet throughout spring (Elevation 643)
Felt grainy
A few really small pebbles
Made palm ball - broke with a light quick poke of the finger

SS2) At bottom of orchard field - never really wet (Elevation 638)
Felt smooth
A few really small and medium pebbles
Made palm ball - broke with a light quick poke of the finger

SS3) Below house - has held water, but not through summer except for 4 years ago when I dug a test hole for water retention...foundation drains to daylight here (Elevation 586)
Felt smooth, cool and somewhat sticky
A few really small and medium pebbles
Made palm ball - did not break with a light quick poke of the finger

The one in the middle seems to have a grade from fine to course.
You need that so that all the granules have plenty of mates to stick too.
Sudden changes of grading shows a weak spot.

You need roughly 50 / 50 percent sand / clay

Roll a sausage of material say, 3/8 x 3 inches and let it dry.
If it remains solid after drying thats a good start.

Then rub some between you fingers,
you want some greasy clay and some sandy grit feeling when doing so.

The samples have settled overnight.

Results:

Soil sample 1 has 72% course sand and 28% clay

Soil sample 2 has no definitive line for me to see. As close as I can see...there is 89% fine sand and 11% clay

Soil sample 3 has 68% course sand and 32% clay

Now, I have never done CEB making before, I am not experienced with the proper clay to sand mixture. I have, had experience with working with sandy, silty and clay soils. I was a heavy equipment operator who has dug and refilled my share of holes and moved plenty of soils. Sandy and silty soils flow very well and won't support much weight before collapsing. The more clay in the soil, the more vertical the trench I could dig. Highly clayey soils can be undercut and still hold weight. BUT, if the hole was left open for a long time, the top and sides would dry out, crack and eventually become very hard, then brittle and crumbly. The more clay in the soil, the longer it would be before it would become unstable, but still, it would fail under moderate weight.

What is the clay "Goldilocks" percentage? That relies upon on the companion sand texture, right?

The overnight settlement is the important one.
#2 is no good and the percentages you provide show that some clay is in the #1 and 3 bottles.
Make the sausage and see what happens.

My wife and I went out today to test a Cinva Ram block from each of the locations of soil samples 1 and 3.

The first test at location 1 was a failure. The soil was so damp that it would not flow into the Cinva's cavity. It clumped and fell into the form rather than flow smoothly. There was too much air space in the mixture as a result. The block would not stick together. For the second test at location 1, we slightly packed the mixture before compressing. We packed too much as we could not make a complete stroke of the handle. I actually bent the handle I was using...a 1 inch piece of black iron pipe about 5' long. We tried to lift the resulting block from the Cinva and could not. There was so much moisture that the block was bending in the middle and was breaking mid-way from the bottom. We left soil to the air to let it dry before trying it again at a later time.

Next, we went down to location 3. Again, I cleaned off the topsoil to get away from the organics. The soil did not feel as damp as the 1st location. While the soil didn't flow like dry sand or water, it was easier to fill more completely with less space between the particles. The brick was solid enough to pick up from the ends without cracking. I was impressed! So much so that I had to stand on it to see if it would hold my weight.

I did say in another post somewhere that I had a Cinva Ram and was giving it away. This is it. It works about as well as the person using it. The brick dimensions are 11 1/2" x 6" x 3". Not quite a standard, but I made it with what materials I had...and I wasn't thinking ahead. Most likely the latter. I'm not sure, it was 7 years ago or so I built it. I do know it is very heavy. I am guessing close to 90 lbs. without handle and a supporting base the new owner would supply. Shipping would be expensive, though it would be a cheap alternative for those who have been looking at a $900 purchase price elsewhere...plus shipping.

My wife and I would happily give it to someone who would come here to pick it up. We are also going down the east coast late December, 2021, to Florida and could bring it with us if someone would like to meet us to receive it as we pass through.
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We know we will be building a hydraulic press as we will be requiring over 200,000 bricks for out buildings in the next couple years. While we have found this press works to create a brick, our limited attention spans combined ( and ability to build the hydraulic press ) will not allow us to make that many bricks manually.

Back to the task at hand...I have made some "soil sausages" by squeezing the soils from the two locations by hand. I now await the result once they dry in a couple days.

That moisture meter is clever.
I wish it was accurate.

I took a sample of the soil I used to make the brick from the second location. I weighed it to be 618 g in the container. I emptied the soil onto some aluminum foil, crushed the larger chunks and put the soil out in the sun to dry. After 4 hours in the sun, I brought the dry soil back in and placed the soil back into the container to weigh it again. I get 533 g. Subtract the weight of the container from both measurements.

I know...MATH...UGH!

618 g - 49 g = 569 g (Before drying)
533 g - 49 g = 484 g (After drying)

Subtract the two measurements to get the weight of the water that had been cooked/evaporated off to find the amount of water that was in the soil.

569 g - 484 g = 85 g (Water weight)

Divide the water weight by the original (damp) soil weight to find the percentage of water in the soil.

85 g / 569 g = 14.9 % (Water/Moisture)

Slightly more than I was expecting. Still, I think this location is the preferred location for me for two reasons. It has about the right amount of moisture, clay, PLUS when I sift the soil I get all the smaller rocks to place in my driveway! The other two locations appeared to have rocks that were larger than I wanted. I need lots of rocks smaller than 4". I have those in this area.

We still need to see what news the "sausage" delivers. I could not roll either location's soil into a sausage so I just had to squeeze them in my palm. Location 1 was far too wet. Location 2 was very close. I could roll the soil into a wiener, but could not roll a sausage.

I think that while I am digging for soil for our bricks, I will also pull some soil off to the side to separate out about 100 lbs of clay for my wife to make some bowls, tiles and other stuff for our house.

Hi Anthony,

I'm really curious how is your brick making progress. I wanted to make CEBs for my house but then realized that preparation of my soil - hard as rock in summer would take way too much of my time. You also mentioned that you need 200000 bricks. It's a huge number of bricks. I used 9500 for my house - slightly bigger than dimensions shared in your first post, and it took me 4 years - from foundation to roof and I'm still not living in it.

Hello Anthony Friot,
Thanks for sharing all this detailed information about your project.
I hope you were able to complete it successfully.

I'm working on a similar project in Upstate New York: double wall earthen wall with middle cavity for insulation (aircrete).

I already have good hydraulic brick press and want to customize my bric mold for a curved wall.
Do you have a good recommendation for a welder fabricator who could help making my brick mold?

What dimesions and radius do you require with a curved block?