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Hempcrete and Coco-crete - Possible Atlternative to Hollow Block/ Concrete Construction

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 Simple Hempcrete Binder Recipe


4 parts Hydrated Lime

1 part Mortar Sand

1 part Portland Cement

(find fresh hydrated lime that is no more than 3 months old and has high calcium, like 98% plus.)

Mixing Instructions for Wall


You can use either a drum mixer or a mortar mixer to mix your Hempcrete; whatever you have available. You can even mix by hand in a wheelbarrow but wear gloves as lime is caustic and will burn your skin.


1. Start by placing 1 part water into the mixer, bucket or wheelbarrow.

2. Add 1 part binder. Mix for 2-3 minutes till you have a slurry

3. Add 4 parts hemp and mix it all through.




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Just to add to your research load you may consider checking this guy out... http://www.timbercrete.com.au/


He utilizes sawdust but I can't see why the technique cannot be applied to any natural fiber such as hemp, coconut or whatever.


I contacted him about 5 years ago to inquire about getting a license but did not proceed at the time because it was beyond my capacity to organize the complete process at the time.


Given his 'green' credentials he may be interested in the publicity of supporting a Philippines development.


Here is an extract from their website,


Timbercrete walls offer exceptional bracing values and lateral strength and has a unique
         resilience that is unmatched by any other masonry wall system, making it the ideal choice
         when building or rebuilding after floods. It is the only masonry wall system tested in
         earthquake simulation tests in New Zealand that is proven to withstand contortion forces
         of earthquakes. It is not brittle like clay fired bricks or concrete, and it’s resilient (semiflexible)
         nature provides a number of unique advantages.


When rebuilding, Timbercrete can easily be nailed and screwed into just like timber,
         making the connecting of shelves, pictures and other fixtures a breeze.


Timbercrete is so resilient that it is even bullet-proof, while other masonry products
         shatter or explode when exposed to a various array of weaponry. It remains bullet-proof
         even when subjected to a powerful .50 calibre armour piercing projectile. Tests have
         demonstrated such projectiles will only penetrate to a depth of 50mm with a small entry
         point hole.


I have no financial connection with the company whatsoever and my lifelong interest in low cost alternate concrete building processes was inspired by the high cost of building Australian homes and 7 years involvement in R & D at an Australian hardwood sawmill.

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I looked into hempcrete myself for some time. From what I can see the huge advantage to it is that hemphurd is VERY high in silica and when it is mixed with lime it PETRIFIES. Yes that's right it turns to rock and their are bridges still around made of it that are well over 1000 years old.


Downsides are in many places its hard to get hemphurd and when first built it, it is rather weak it takes several years maybe even decades to fully petrify.


I dont know anything about the other materials mentioned but I'm unaware of anything else that petrifies so easily.

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Here is an idea to help build your home cheaper and even start a small profitable business at the same time.



You can shape the mud mix into a metal brick molds and set side by side on the ground to sun dry. Then stack the mud bricks in an earthworks, as they do with copra dryers, and cover with a thick layer of rice hull and then burn the rice hull with will fire dry the bricks giving it strength. Remove the bricks and stack on site, scrap up the rice hull ash to be used to help make the next batch of bricks; repeat the process until you have the desired number of bricks.

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Don't need bricks for an underground tunneled structure but hempcrete to plaster the walls would probably be ideal.





Located at the base of a gently sloping hill and opening onto the
placid Eco-Village lake, MOTHER's "root cellar turned cave" (it was too
nice to leave to the vegetables) was the source of a good bit of
excitement when it was built in conjunction with last summer's
Earth-Sheltered Homes Seminar. Of course, part of the attraction of this
type of shelter is its simplicity . . . not only of construction and
design, but of maintenance as well. Because there are no exterior walls,
for example, the structure requires no summertime consuming paint jobs.
And two (hardworking) people took only five days to build the cave . . .
using some shovels, a mattock, an auger to dig the chimney and a tile
spade to smooth the interior.

Furthermore, with six to eight feet of soil "roof" providing insulation
and protection from cave-in, a solar chimney, and an air vent at the
threshold, our burrow will typically maintain a closed-door temperature
of between 45 and 60°F year round. So, if a similar cave were located in
a hillside next to your home, it'd be great not only for storing cool
loving vegetables, but for prechilling milk, and-with a smoldering fire
built outside the open door perhaps for smoking meat or fish as well.

The 6' X 7' X 10' chamber is all but airtight with the door, floor vent,
and chimney flue closed. When opened, though, the latter two provide
the grotto with a continual current of fresh air. You see, a 6"diameter
ABS plastic pipe-just inside the door-drops down to five feet below the
floor vent and then gradually slopes away from the entrance (running
within a gravel bed) before turning upward to end in an intake that
breaks the surface about 25 feet away. The cool pipe works, in
conjunction with the solar chimney, by drawing outside air down through
the intake to the buried tube and into the chamber.

The chimney
itself-a well casing that's been painted black to absorb solar
energy-projects four feet above the ground, and draws cool air from the
cave into its sun-heated metal length. As the rapidly warming air makes
its way up the chimney, the pressure inside the cave lowers, and more
ground-cooled air flows from the buried pipe into the cave to
reestablish atmospheric equilibrium within the chamber. This constant
give-and-take provides an effective and natural ventilation system. (See
MOTHER NO. 73, page 134"My Mother's House: Part IV"-for more details
about this type of setup. To order back issues, turn to page 68.)

The tube also keeps the cave nice and dry, since at the lowest point in
the pipe-there's a "T" which allows any moisture that has condensed
along the line to drain away.


A prospective cave dweller needs to be absolutely sure that the soil
he or she has chosen to dig into is of a composition that will permit
safe tunneling. The ceiling of the burrow will likely have to be at
least four feet below the surface to guarantee that the work will take
place in the dense subsoil that makes excavating such a passage
feasible. Our subterranean shelter was dug out of heavily weathered and
decomposed (yet very sound) rock that was 30 to 35% clay.

The most important consideration in the excavation of such a nook is to
maintain a perfectly arched ceiling during all phases of the
construction process. This can be accomplished by using a pattern, made
from either lumber or rebar, shaped to match the proposed arch of the
chamber. To form the initial curve, we simply placed our pattern against
the side of a cutaway hill . . . etched its outline into the soil . . .
removed the guide . . . and then dug out the doorway with shovels.
After every half-foot or so of forward progress, the pattern was moved
back into position to help us maintain the shape of the ceiling vault.
Painstaking accuracy is required because the structural integrity of the
entire cave is based on attaining an arch that is not at all tilted or
lopsided. Obviously, it's crucial to get it right the first time!

(Of course, since the retreat isn't intended for actual residence, it
may not tall under the jurisdiction of local building codes. But to be
on the safe side, you should investigate any such ordinances in your

In order to help maintain the correct curve and provide a dust-free
interior, it's best to protect the sculpted walls and ceiling with metal
lath and a plaster composed of one part portland cement and four parts
excavated dirt. This produces a smooth surface that won't flake or chip
off, and that allows the digger to follow his or her own decorating
fancy . . . adding murals, stucco, or even wallpaper!


total cost of MOTHER's project was approximately $60. This included $30
for the solar chimney's ten feet of well casing and $25 for the plastic
intake pipe. We've found that our cave stays quite dry and comfortable,
even after several days of prolonged heavy rains ("toad drowners", as
they're called here in western North Carolina). In fact, upon opening
the door after a period of many months, we were delighted to find not
only that all the interior surfaces were solid and dry, but that the air
within was cool, fresh, and thoroughly pleasant.

Whether the burrow is used as a demonstration during the seminars, as an
Eco Village workers' hideaway for a reprieve from the summer heat, or
simply as a private resting spot from which to watch the sun set over
the lake . . . this snug, appealing cave is a welcome addition to MOM's
property, and should be useful for many years to come.

Carter, who conducted the Earth-Sheltered Homes Seminar for the last
two seasons, will be back again this year. Dave has written three books
about underground construction. Digging In and The Grown Man's Tunneling
Guide are available, for $7.50 and $4.95 respectively-plus 95d shipping
and handling-from Mother's Bookshelf °, P.O. Box 70, Hendersonville,
North Carolina 28791. His newest book, Building Underground, will be
available soon.

Edited by littlejohn
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I plan in a couple of years to build a small cave room (10'x10'x8') into our hillside to be used to grow mushrooms.





Edited by JamesMusslewhite

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If you have a hillside with clayish soil that tunnel would be a lot cheaper and in my opinion better. No limit to how far you can go as long as its under your property or the neighbors don't find out.

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If you have a hillside with clayish soil that tunnel would be a lot cheaper and in my opinion better. No limit to how far you can go as long as its under your property or the neighbors don't find out.

I have two hillsides and my land is a valley system with clean flowing water running down both sides of the rice fields and caladium fields that run the length of the center of the bottom land between the hillsides. I do not know the composition of the soil to know at the depth I could bore into the hill side. Perhaps once I build the mushroom growery room into the hillside I will have a much better idea of the limitations. .

Edited by JamesMusslewhite

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This is just cool and would be easy to have fabricated to fit your specific requirements according to your need.


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I have one of that guys books and he mentions that many of those tunnels have been made into very nice houses. He even mentioned one decorated to look Victorian. Have been dreaming of something like that for years and haven't had the chance to try it.


Would be better than this guy had for sure. Makes you wonder if their aren't a few of them around no one knows about. lol




When authorities on Massachusetts's Nantucket Island recently discovered that
Thomas Johnson had spent the last decade secretly living in a
158-square-foot bunker beneath some of the priciest real estate on the
eastern seaboard, they were astonished at his amenities: Belgian stone
floors, cedar paneling, skylights, a queen-size bed. Intrigued, we
caught up with the 38-year-old recluse, who's staying
with a friend while he appeals his eviction notices.

So ... you're a hermit?

I don't fit the bill of an underground kook. And I'm not prejudiced against anybody. I hate everyone equally.

You were eight feet underground. Was it, you know, kinda dirty down there?

When people think underground, they think dirt. My place is not dirty at all. I'm a cleanness freak. People are envious.

What about the winters?

It never got colder than 52 degrees. The stove would

eventually heat up the stone floor. The stonework was beautiful. It
looked like I had a team of Aztecs come in there and lay it.

Must have been pretty lonely.

Every day I got to talk to the animals. Red squirrels. Chipmunks. Owls. They liked to listen to me talk.

Any critters you're not so fond of?

Rats. One time one dug in through the back vent into

an empty space behind the wall. God almighty, did that infuriate me! I
drilled holes and shot the space full of foam. I hope I nailed the son
of a bitch with foam.

Did you ever think, gee, it sure would be nice to order a pizza?

Hell, no.

So what happens next?

I've got a cliff dwelling in the Catskills and a

bunker near a waterfall in Pennsylvania. I'm like a beaver. I can carve a
place into the woods, and you'd never know it was there.

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Is the rice husk you are using carbonized or not? Carbonized rice husk can be used as a replacement for concrete to a point without losing any strength, but not plain rice husks.



I`ll use  non carbonized rice husk.. I have used it in a 2 inch render coat on my wood fired oven.. Still there with no cracks!.. 

From memory carbonised rice husk actually strengthens Portland cement in a 10% ratio so lots to think about right there.

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@ fred42,
Making Carbonized Rice Husk is easy to make and only takes 1-2 hours.




How to make your own carbonizer




Funny enough,I  built a rice husk cooker about 2 months ago.. It converts the gasses to a blue flame for cooking and produces excellent bio char..

Mine still doesn't have the top burner unit though.. Still trying to find a metal shop to give the design to..


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I thought those gasifier cookers were neat. Not generally available though.

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Ive got mine going now.. Turn on the fan and it boils a kettle full up in about 5 mins..

One day I`ll build a proper husk gasifier that runs a genny for free power.. Like this.. 


Then I`ll open a husk char hollow block factory... This time next year Rodney!!

Who says it can get boring here?

Edited by fred42
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Any one thinking of doing a business making mud-clay bricks need to look at this rig in Laos. They are using a process for the extrusion of the finished mud-clay into elongated blocks where it is than slid to a hand-pulled brick cutting unit. the Unit cuts the elongated blocks into single bricks and slides them over onto a piece of wood that is them removed and stacked. I bet 3 men could make over 500-1000 unfired bricks a day..


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