Rammed Earth Wall + Rubble Trench Footer

Hello all, I am currently designing a home/structure in Southern AZ on 40Acre's. Currently testing the soil for Rammed Earth Walls and so far it's looking prime. However my budget doesn't support concrete footers & I cant seem to find info/engineering for rubble trench footers under these walls. Any direction would be greatly appreciated.

Concrete foundations are the best.
You plan to build a house but cannot fund the foundations?
Something is all wrong about this plan?
Either;
- house too big
- importance of foundations not accepted

Welcome to the Forums T!
Please give us a little more info about your, "home/structure in Southern AZ" so we can be more helpful. People have been building earthen homes/structures in your area for thousands of years without concrete footers and many are still standing as US National Parks and historic monuments. There are many ways to build out in the Southwest using materials at hand.
How big is the structure? Have you drawn up a plan yet? What kind of "rubble" is available? What is the drainage like on your site? Is this a forever home or a building that will be repurposed when funds increase for a more permanent home down the road? What county are you in?
Info/engineering data for rubble trenches is available but help us narrow down the subject by telling us more about your plan.

Thank you for the replies  let me clarify by what I meant about budget, I'd rather not spend.... for numerous other reasons I prefer exploring all avenues when creating. Instead of living in the confines of a 1 way mentality. I believe F.L.W used Rubble Trench Foundations, among many of the ancients whom structures still stand firm.

Mainly from a sustainable and flexibility stand point, It would be great to utilize the various materials on my property in Cochise county. Zoned RU, having already opt'd out of inspections and building permit has been approved. Standard Septic was one of the requirements in order for approval and once every 6 months a fire inspection, verified by photo submittal.

All other utilities are roughed in, I can't go full solar as my CNC's require constant power and no one seems to know the solar calc convertions at a base point. Money can buy pretty much anything but I am not the LEGO factory. Ill have to figure that one out as I go.

I have the freedom to build finally without inspectors dictating everything. More importantly, Id like to have some fun with the freedom. As we as flexibility with a building method to add as i see fit. This won't be you traditional house, more of a livable flex space.

How often does one get to submit only a site plan with minimal requirements in order to obtain a 5 year building permit. While opting out of inspections? besides set backs, septic, all they wanted to know is how big the site will be, which is 100'x100', porch space 3000sqft, garage space, 3,500sqft, Living space 3,500sqft. Wall heights not to exceed 30'.

I may do containers still, however I am somewhat bored of heavy metal welding and grinding knowa days. Besides the market it flooded and that usually detours my efforts down an avenue, I'm not into the tiny super Adobe's or Hay methods, maybe CMU, maybe cast my own block. Self made soil samples seem to be the the correct ratio for RE, pottery is all over the place so I think this is the right spot. I will send some core samples off the Vann engineering for a compression test and soil analysis.

Different areas of the property have slightly different earth, sandy loamy with other areas that have plenty of rock. I can build sifters to acquire the appropriate sizes for the foundation/Footers with a grade beam.

I do draft plans in autoCAD, by trade an industrial designer. This will be the first project I get to build the actual structure, I have designed and built pretty much everything else and usually do when contracted to build out commercial or residential space.

As for now I want to affirm the system before actually spending the time drafting the floor plan. After this foundation is figured i'd like to move onto a waffle grid ceiling, also limited info per "residential" application. However I will have the ability to make my own moulds, same goes for the RE, in which I would like to incorporate a pattern into. Lots of fun things to play around with come the build.

Just because i get to bypass inspections and some code reg's doesn't mean I want to cut corners. When developing anything I care most about safety and liabilities. I won't sleep at night building garbage, let alone putting something out into the world that may hurt someone. If I can't build it to an engineered and safe quality I won't do it. With the weight of these walls the foundation is critical, especially if I'm able to go up 30'.

Hi T,

Welcome to Permies.

pardon the typos, spell check on my phone likes to fight.

Thank you again for any professional advice and or positive solutions.

Thank you for providing background info and perspective T.
Given that you are a design engineer and you have the freedom to examine ideas beyond Cochise County, I'm guessing that you might find New Mexico's Earthen Buildings Materials Code useful as a data point for your inquiry. Yes, the code does specify some concrete for the grade beam that is built atop the rubble trench:
"Concrete grade beam.  Rubble filled foundation trench designs with a reinforced concrete grade beam above are allowed to support rammed earth wall construction.  An architect or engineer registered in the state of New Mexico shall certify the grade beam/rubble-filled trench design portion."
The rubble trench specifications could be ascertained by contacting a certified architect or engineer. The next exploration could examine concrete alternatives or, at the very least, ways to minimize the length of the concrete beam atop that trench.
I look forward to hearing from the professionals who might share ideas here.

T Land wrote:Hello all, I am currently designing a home/structure in Southern AZ on 40Acre's. Currently testing the soil for Rammed Earth Walls and so far it's looking prime. However my budget doesn't support concrete footers & I cant seem to find info/engineering for rubble trench footers under these walls. Any direction would be greatly appreciated.

For CEB walls Jim Halleck recommends the rubble trench be one foot wider then the wall thickness. Here's his video:


I built a 2x6 stud framed wall infilled with cob and light clay straw on an 18" wide rubble trench. Here's my video:


You're probably going to need some conventional concrete for the grade beam but it will be significantly less than a whole footer. Lately, I've been tinkering with lime cement stabilized grade beam but wouldn't feel confident to use it for a house.  

You certainly  have a good concept of what your plans are.
I suggested concrete to save time collecting rocks.
But time does not seem to be an issue when I see plans for a tremmel to sift rocks and the abundance of them.
What will you cart the rocks with and would you hand load them or use a loader.

Would you be able to collect rainfall and use it, my signature has some details?
Rammed earth is easier with a bot cat style of loader to lift soil and shift the boxing required.
Also a large compressor and air rammer saves time over a simple tamper, would you be going all hand
operation or use some mechanical assistance.

wow! thank you all! @ Amy, this will be a permanent structure, site is flat, with about a 5degree slope behind (North) to the well 100' away, Flood zone X, figured of directing water catchment back to it. Not sure if that creates a sink hole. I plan on building staggered RE basins to hold and or re direct the RE Gardens and general landscaping. Up the driveway etc.

I'm reading your previous message and answering some questions you had, my apologies for being all over the place. I am in Cochise County, by the way!! look at New Mexico's code on the various building methods, how cool is that. I just took a read but will have to revisit it probably many times. I don't need any stamped plans but would happily engage with a engineer to design the foundation.

Ultimately what Id like to know is various footing sizes for various wall heights and loads. Seems like a 24" min wall is the way to go, as it is self buttressing, aesthetically buttress's can be neat, I don't mind over engineering this thing either. By the way, do you know of an engineer familiar with this method? I'd probably engage them for the concrete ceiling's etc.

Worst case scenario i will frame it out of steel and pour or just do metal roofs. I'm hoping to figure out a waffle or ribbed concrete system, thought about aircrete but i've seen some people have serious issues with that method. I'd like to have some transparency between levels to allow light in, maybe some glass sections in between the ribs type of thing.

@ Aaron Thank you for the vid's I did see that one with Jim, your video is neat. How is your structure holding up? Yes concrete has its place, I will use it for the beams and Lintels, Most likely I will also frame out all opening in some sort of steel system, as i plan on making the windows.

@ John Thank you also, it would be great to be able to sorta build as we go, a general concept for cost and engineering purposes but you know how it goes. Sometimes you start building something then come up with a new idea or change.
Time is not an issue, other then getting out of this Airstream! haha, normal size shower etc. I do love concrete, i've made lots of stains, stamps and cast tile and blocks, it does give peace of mind. Seems like a batch plant is in the works, i'll weld up so sifts for whatever sizes I need. Also for the driveway, approx 200'x 40', i graded the driveway and site last month with a Kubota L47 Backhoe, first time, had lots of mesquite's. Some of those roots were an easy 20'!!

I think this is a job for a backhoe, as I can probably use it to lift atleast up one level, idk, depending on Level1 flooring which will probably be concrete, maybe RE... would be great to get a forklift to lift way up.

Rainfall is abundant during the summer, I had an idea of collecting rainwater in the roof design, dropping into internal catches within the structure, gravity feed applications... I know RE cant be subject structurally for such, but maybe a bladder of sorts. I've been looking at the pneumatic rammers and eventually stumbled across one from the UK. It is so sweet, reduces arm vibration 70%, compared to all the others. I see people do the dry mix with the buckets on machines but potential inconsistencies are already giving me nightmares! Some sort of mixer for that job starts to make me feel better. Seems like a waste of fuel also?

@Autobot super funny

Thank you all, I'll upload my site plan so you all can see. It's as vague as was required, sorta not true, i heard of people getting approved off napkins but that's not really my style. I've been drawing for a decade but I really don't like to until material calcs are needed, rough designs,most of the time I prefer spending that time on physically doing. Drawing for machine uploads is fun though.

I kind of rushed this drawing the day before moving down but it served its purpose.

Are you speaking of a concrete roof structure, or is it a first floor?
Reinforced Earth is not the same as rammed earth!
Water storage is best done in tanks, and maybe circulated with a 12V RV pressure pump.
Pan mixers are best for mixing rammed earth, because it seems pretty dry where you are building, the addition of a set volume of water
to each batch and if the loose soil is kept covered, that water volume will be consistent.
And the moisture content of your soil will be consistent which is important.
https://www.rammedearthenterprises.com.au/rammed-earth-information-for-professionals/

https://www.naturalbuildingcollective.com/from-the-ground-up-approaches-to-building-a-foundation-for-your-natural-building/

Good evening John! I am thinking about some sort of concrete 1st floor and roof, possibly concrete 2nd floor and roof. Waffle grid or ribbed. Probably ribbed, seems like a more manageable design as most existing waffle moulds are for massive commercial applications and I'm not sure developing my own mould with a engineer is possible for structural applications. I'm confident in developing such a thing for aesthetics, such as a type of patio lid or block style screen walls.

I googled reinforced earth vs rammed earth, nothing popped up. I'm wanting to do reinforced earth walls, like the SIRE wall, lifts of earth with rebar & concrete lintels. Not Compressed blocks walls, is that what you are talking about?

I have thought about compressing or casting blocks for level 1 flooring. Instead of a concrete floor. This is sorta 2nd on the priority list. I say sorta because if creating a second level which i'm really looking to do, ends up not feasible, I'll go sub level 1, possibly 2. A compressed block would be great if applicable, CMU at the least,   Figuring out the footers per my soil and the roof or 2nd floor options is what i'm pretty fixated on.

Water storage tanks seem to be the most practical application. With the various things developing I'll end up purchasing some of the components for ease and peace of mind. I will still build around the tanks for security and aesthetic purposes. Or put in ground.

I have not seen a pan mixer before, i'll start digging into that but sounds like the way to go, as you said i have to have consistent batching and ramming. One popped up on ebay, i'll attach a photo to see if this is what your talking about. However this goes It just needs to be scaled right, from the backhoe etc. bucket size to the mixer. Surprisingly as dry as it is out here, the earth holds moisture from about 3" down to atleast 5' i'm sure its damp well beyond.

I mentioned before I just did a model size rammed earth test. I literally dug a 1' deep hole, and packed a 1"deep 5"wide 8"high mould. Without no additive and the moisture that was already in it. Which looked like the consistency people show online per the drop test. Let it cure over night and it was pretty solid, i was able to snap it apart shear ways to notice some moisture still inside, the 2x4's i used didn't let it breath enough i suppose, also temps that night got to about 18f. After it sat in the sun it really hardened up. I weigh about 180lbs and can stand on it without any break, even the shear strength is impressive with no cement.

Those links are great, i just did a quick read through but will keep revisiting. Some important engineering consideration per the soil. type. I was thinking you couldn't possible over engineer footer, turns out you can. Per sandy soil with rubble, one would think you could just dumb an unthinkable amount of large rocks and it would be stable. When really it's just a matter of time before that spreads out into the surrounding damp sand? it's like a bond beam need to be not just on top but below also? i'm going to get back to those links right now actually.  

Thank you John i'll keep getting back on here in the evenings to check posts and give  update aswell.

As a Civil Engineer, I have been thinking about the comment you made about the rocks and sand slowly moving.
It could be that in the past walls were 24 inches wide or wider and the pressure exerted on the rubble foundation may have been really low.
Just like a earthmoving dozer, they actually have a low psi on the ground surface.
Rammed earth which I think you will getting an understanding of from my link, usually has walls that are narrower, and thus rubble foundations may not work.

I had suggested concrete because it covers a lot of mistakes, takes a short time compared with rock collection and sorting and works generally.
I have built many homes and buildings.
About number 4 was timber entirely by hand tools.....!!! NEVER AGAIN because of the time factor.
I would not have done half what I have achieved if I took the slowest way to do things.
Amongst my Engineering work, I build sports cars, race sidecars, run a small farm, have a flyscreen repair business and I travel
about 500 kilometers per week and get all things done in a rambling way.
Using hand tools etc I did nothing but build.
I guess the moral for me is, that even my time has a worth greater than zero.
I achieve other things instead of sorting rocks for 3 weeks by hand.

Yes I am thinking of the walls at 24"+ thick. Lifts of the mix with portland cement, in 5"-8" increments. It looks like those diagrams are referring to narrow walls, I don't see a footer design with a 24" thick wall sitting on top.
  per your analogy that must be how the megalithic structures have stood so long without much movement. Massively thick walls 3'+? I know various parts of the world used different combinations of materials or shaped rock walls but still extremely thick, I think I don't know for sure but appears some of those structures were just sitting on the earth with no footer.
Like the pyramids, not a living structure and few rooms/tunnels so at there base the weight distribution spreads out at around 95+%at ground level?
I wonder how much those structures have actually sank during settling.

Anyway I'm thinking the 24" thick wall, maybe tapered, 24" at the bottom at 18" up top. If you don't think i'm crazy already you probably will after saying I was trying to figure out how to make these forms in a way to actually make a pyramid. That wasn't solid as the pyramids were built. Actually living space inside. It's a tricky one.

I think with a large enough backhoe and a few screening grids to separate the different size rocks it could go quick enough. At least 250' linear of footing. Defiantly not doing this by hand, your timber job sounds like my last project. I'm beat from it, funny how some people think laborious work only makes you physically stronger.

I am finally able to hand a lot of the work off to machines now. Extremely grateful for that but this is still going to be a lot of work. Hopefully just less on my back. Sounds like you have quit  the operation going on and are well versed, knowledgeable. Are you still civil engineering?

I try an develop as much product, tooling or techniques during my process of building something. It's like instead of the time and money just going out towards something that already exists. May aswell try to develop something that may yield an additional return.

There are some attempts in building around this area but not much. It's possible this project inspires people. Biggest difficulty is availability of equipment and resources. That's why i'm not spoofed to actually creating a small batch plant and acquiring the machines and tools for this build. I'll be able to rent equipment out or just do the builds for them. At the least, i'll be able to continue building as I feel like it.

Are you located in the states? I have to reach back out to the engineering firm in Tucson AZ tomorrow. I don't know what they want from me to test compaction. I imagine a tube packed in the manner im planning on building with. I think i'll search for a structural engineer for some designs on the footer and possibly the additional levels/roof sections.

I would look into CEBs Compressed Earth Brick (unfired). I believe this is what you may be looking for as a solution to your foundation.  There are plenty of ways to weather proof these bricks too. A little bit a digging (no pun intended) on the internet will reveal the various means to weatherize these bricks. Bonus for you is that you are in an already drier environment which makes things work cheaper, faster and overall easier. I have high quality clay (potters / china grade) and will be making roughly a hundred to hundred fifty CEBs a day through the months of June and July to use in a house this year and I am located in up state Ny. Good luck to you.

At our school SECMOL, we built most of the buildings 25 years ago in rammed earth with stone foundations, and no concrete in the foundations. Stone masonry, not random rubble, I think, if I understand what that means.

In our most recent buildings, we put in a concrete tie beam on top of the stone foundation, and at window lintel level, and under the roof, because over the years we've experienced the news of major destructive earthquakes in neighboring regions, despite there not being major or destructive earthquakes in our region in recorded history.

I still work as a Civil Engineer, and I do lots of other things. as well.
I actually manufacture and sell  a Compressed earth Press and have done so since 1972!
I live in Australia where the rainfall is about 16 inches.

Rammed earth can have insulation set inside a 24 inch wall.
Lime can be used instead of portland cement.

The alternative to concrete foundations often mentioned are masonry slabs.
I have seen a 5 storey brick hotel built in the 1890's in Australia built on basalt slabs 15 " x 12" x 48" and
they worked well.
But the effort to move them was immense. Thats why I always look at concrete!

Good evening! and thank you all, I was seriously confide ring CEB's prior to rammed earth walls. I am familiar with the auto machines and some of the manual ones. its crazy how many other countries are manufacturing the various types. In the states seems like there are a couple options and no mould packages.

So if the compression on a CEB is the same as the packing of rammed earth walls (SIRE Wall)  is the same. What makes a CEB applicable for the footer instead of rammed earth with rebar?

@ John, by concrete masonry slab do you mean a hollow core CMU footer? cells filled with concrete? I've always wanted to go to Aus, i've met lots of Australians and were all very cool. Most of the rammed earth wall literature i've read has been from builders out there. What machine do you make?

I'm thinking i'll have do to a combination between these systems. I do want to go sub level also, maybe 1 floor up and 1 down, or two up and two down. Being it seems rammed earth walls never go underground? i'll have to go block underground. I was originally thinking CMU for anything underground, however i don't want to be reliant on someone else producing a building product for me. Also the QC issues those blocks seem to have and the excess mortar to keep it square. CEB's instead get a little earth slurry in between correct?  

our annul precipitation is about 14.2", monsoons during the summer. Crazy high winds. unpredictable, as if this build wasn't going to be tricky enough. Made contact with the engineering firm for compression testing, seems pretty inexpensive for that.

Just rolling the CEB's around my head again, I kinda took a break from them for awhile while i focused on the SireWall method. I submitted some RFP from some companies here. machines that only produce one block style.

Do you send out to a lab for soil analysis before starting? what are the critical tests i should do or send out for ? and this is the same whether it be a CEB or Sire wall correct? the soil mix is identical between the two isnt?

T,

I built CEB house. In California it's required to test the bricks made on site by the owner. I purchased a hydraulic, motorized machine, but it turned out to be so much labor. The worst part was soil preparation. It had to go though a sieve an it would take eternity, so I purchased a rock crusher. Even if I bought clay separately I still would have to use the crusher, because it had granules. Even with crusher it would still take way, way too long. None of my bricks would pass the laboratory test. I was stabilizing them with cement and they still had too much water absorption. I decided to buy blocks in Arizona. Machine was eventually stolen. Since then I decided that I will be building custom structures but will not making materials from scratch. My time has value.
Nonetheless I still mill lumber, carve granite slabs, but making bricks - no.
I have found one brick that I made, it was left in the grass for 8 years and it's much, much more resistant to moisture than the bricks I purchased, so probably they would also fail the test.

As far the mortar between courses, we did not use any slurry. just clay mortar also stabilized with cement. The CEB blocks have variating height depending on the force, current mix, moisture during pressing, so regular laying approach was used to lay them on 4" height.

T, what does the T stand for?

@ John, by concrete masonry slab do you mean a hollow core CMU footer? cells filled with concrete?.........
 Most of the rammed earth wall literature i've read has been from builders out there.
  What machine do you make?

I actually did not mention 'concrete masonry slabs.' This error is why there is often confusion.
I used the terms;
Concrete slab - a solid reinforced concrete slab usually of a consistent thickness, maybe with thickened 'edge beams'.
Masonry slab - solid basalt blocks 15 x 12 x 48 inches.
I build the "Dalrac mud brick press" it is similar but bigger than a cinva ram.

@ Cristo This county in AZ has an opt out for builder owners, no inspections.   Regardless i am seeking professional advise especially with structural related components. Currently waiting on a nearby geotech firm to get back with what type of service i need from them in regards to testing my soil psi.

@ everyone i'll upload the form and see who knows what service I need to gauge the psi strength test. It's under lab testing, is it the soil and agg proctor? they seem super busy and are taking forever just telling me what it is that i want. I still need to know how they want the sample.... i'm assuming a prepackaged cylinder of a certain diameter and length.    

So far my crude blocks/mini walls are extremely strong. Without any additives, i just dug a hole and used the already damp clay/sand with fine agg. I don't think it matters which method it's used for, seems to be the ideal everything. When I graded the site i left piles of dirt that were essentially dust only, like baby powder. After dampened and dried they have hardened solid. I was born and raised in Nor Cal, anywhere I lived that soil to me would have been better for pre cast mud bricks.

I don't know though, that's why i'm here, figuring it out with all you good people.

@John my name is Travis, idk where conc masonry slab came up

I am thinking about keeping the footer and main slab somewhat separate jobs, i'd like to attempt some alternative flooring. It may end up being concrete  but something I'll have to do in sections if I can't get a truck out here, Last I checked the nearest place could not deliver.
    I'm still working on the concrete ceiling/level options. Besides aesthetic it is a big reason I'm looking at Ribbed conc ceilings/joist. I can go one beam at a time without running into a continuous pour curing issue. Using maybe the product called the MidMixer. Either precast the beams or pour in place, if the additives required etc end up costing the same as H beams or a C Chanel design I'll probably opt out the concrete ribbs. wood costs here are outrageous and termites. I searched for your machine, I don't think i found it, i searched Google.Au also, do you have a site for it?


Back to a question from my last post, If sire wall compaction&mixture is the same as CEB's. How is there a difference when it comes to footers? assuming both have ample rebar reinforcement and a bond beam on top prior to wall erection. If i need to go with CEB's for anything from the frost level down and sire walls above i'll do that. Just wondering what the actual difference is.

I deleted the post about not being able to post. The reason was that I typed "U shaped" instead of "U-shaped".

still grinding this out, CEBs psi rating is much greater but the mix can be the same as rammed earth walls.

With solid CEBs used for the footers i see how that could be much more form then a rubble foundation. Does this approach eliminate rebar reinforcement? or is the rebar situated in the bond beam and up through the wall?

Been looking a lot at the various machines, wondering how critical it is to have a machine that produces a hollow core "brick" that accepts rebar and conc reinforcement. Seems the difference between a Automatic solid brick machine 8-18k vs hollow variable machines 50-80k. Unless it's an Alibaba import then there are a couple automatic machines with various mould sets for under 10k.

@John, how high would you go with solid CEBS? what methods of reinforcement? or do you hollow core so you can reinforce?

Travis,

I give you some structural answers based on the design by the structural engineer.

Footings: four 5/8" rebars with 3/8" stirrups every 16". Concrete 12" deep, 6" above the grade. In my case all walls are treated as structural, so I have footings under all walls.
I would definitely not recommend any solid compressed blocks for footings. They are not water resistant enough and that's why 6" above grade footing is required and for a reason. The footing has to be solid material.

Vertical reinforcement: 1/2" rebars hooked in the footings, all corners, ends of openings, and every 32" in continuous wall. I used two kinds of 8x4x16 blocks: solid and with two 3" diameter holes for vertical rebars. Holes with rebars I grouted with pea gravel mix, holes without rebars I packed with slightly moist mortar mix.
In case of 16/24" wall I used two rebars on the outside and inside part of the wall, so the rebar in footing was U-shaped.

Horizontal reinforcement: galvanized ladder mesh 3/16" thick every third course (assuming course is 4" high). It had to be made per order, because nobody stocks them for 24" thick (exterior) and 16" thick (interior) walls.
General rule for adobe is not to go higher than 10 x wall thickness, for compressed earth blocks it could be probably higher depending on compressions strength, so I could probably have interior/exterior walls 8" thick instead of 24" or 16", but I love thick walls and that was my choice.

Concrete bond beam: four 1/2" bars and 3/8" stirrups every 16". It was required to be 8" minimum, I poured it 10". Forming it took some time, because the bond beam was going at the angle on interior walls (the roof is two slopes) and I also had to position anchors (custom made from 316 steel) for the roof top plates.

All of this was required per seismic design, but I'm in the area with lowest seismicity in California.
I have used a few pieces of carved granite: portal with pilasters, two windows, bathroom shelves. All of them also had drilled holes to become structural part of the wall.
All doors have arches - from small bricks and from blocks. Over each arch I put 3 rebars 3/8" spanning the width of the arch plus 32" on each side.

If I had to change something I would opt for Catalan vaults, so everything would be 100% masonry. I don't like wood, except in heavy beam version and for door/window/furniture, but still making the heavy beam roof was a bigger challenge than building all walls, which I did with my mason.
Interface between incompatible materials is always a challenge - anchors, barriers, seals, uneven expansion, etc. Because of that I decided that for all small structures that I'm building I will be always erecting vaulted brick ceiling resting on solid and well reinforced concrete beam.

I can provide more details regarding plumbing, electricity, chimney, roofing, if it would help you to make a choice.

Thank you for that info, i'll dig into more once I get the Soil Analysis back from the engineering firm.

Did you submit tests at a Geotechnical firm also?


sand to clay ratio & compressions test to determine psi?

I concur with Cristobal about the Compressed earth blocks.
They will not survive any moisture around them.
Sand / clay ratio depends of types of clay involved.
The info I gave you about rammed earth should cover that point and the simple tests involved.

Travis,

I was using a geotechnical lab when I was trying to make my own bricks.
As far as geotechnical test of the soil compaction for the footing/slab it was waived due to records of tests from that area and known type of soil (sandy loam). It's so hard in its virgin state that when I was trying to dig footers for my barn/coop in summer 2021 I had to use vibration hammer and diamond grinding cup.
Regarding your search for machines I see it this way: either a manual one for a poor guy or a 30-50k for a wealthy guy. Mine was 8k and required a lot of labor, was leaking oil despite new and US made. Expensive machine allows to load with a bucket of a skidsteer or a tractor and the bricks are coming on a belt. Mine was intermediate and would not allow me to make more than 20 bricks an hour with two helpers and I needed 9500 pieces and I also value my time (now more than before). On top of that the soil preparation - the part that nobody is talking much about. Like I said before - my soil had crumbles/nuggets of compacted soil - they look like rocks and needed to be removed with a sieve or crushed. For all of this one needs more hands than just two and it adds to the total cost. Because i don't have unlimited amount of free time it forced me to buy blocks.