HAND MADE ADOBE BRICKS, WALLS AND FLOORS -
QUESTION: Is it possible to make your own bricks using adobe, or possibly fibrous cement formed in molds like brick? How low could you get the cost?
EXPERT: Sure you can do it and get the price down too. Mix Adobe with straw for better insulation and largely-unneeded tensile strength, not as strong as synthetic fibres(they don't insulate much in the quantities used) but more than strong enough for walls in one or two story structures---disregarding labor cost, but with purchased straw (chop it), purchased sand and onsite screened-clay, my estimate for a 4" x 10" x 14" would be ten cents for hand-mixed small quantities. Add for purchase or rental of a pugmill for mixing clay and straw (the hardest part of the operation). Running the straw through a garden-shredder would be easier and more readily available than an electric or hydraulic shear (rotary cylinder or reciprocating four-foot paper-cutter)
Add another five to ten cents for other additives---slaked lime, Portland and asphalt emulsion, depending on how you want to balance out the characteristics. Portland adds compressive strength, straw tensile strength, asphalt water-resistance. In earthen materials, labor cost is always the highest ingredient---and most homebuilders have a lot of unused labor which is valueless unless there are alternative moneymaking activities to invest it in.
Just one problem for me. I like the idea of brick in certain areas mud room, garden rooms, green house etc. but that surface is pretty hard on your legs, hurts a lot more if you fall on it, can be slippery, and dishes etc. will break. It can also appear quite cold. While rugs would help. I'm not sure that condensation, temperature differentials might not cause molds etc. to flourish under carpet, or padding.
EXPERT: The purpose of vapor-barrier is to prevent capillarity-wicking or vapor-transmission from earth (which would otherwise keep floor surfaces damp).
QUERENT: It's the damned dirt, airborne, spilled, tracked-in and ground into carpeting that transforms it into your own private Love Canal for living room, hallways and bedrooms. No wonder allergists get rich. Did I say I hate carpeting? That goes for padding too! A few small braided throw-rugs that you can wash, take outside in bright sunlight, hang over a clothesline or wall and beat hell out of is still my favorite way of putting something soft (and clean) underfoot. Don't know who sells carpet-beaters nowadays though---have to make your own if Lehman's doesn't carry them. In the interior living rooms I'd prefer wood, or possibly laminated wood surfaces, which appear warmer, are easier on the feet, can be covered with area rugs for interest, and are fairly easily maintained if properly sealed, and glazed. Again just my preferences.
EXPERT: Traditional full-thickness hardwood-strip flooring doesn't buckle, is level (unlike most wood-tiles), comfortable and good for low-traffic areas. If you do it, pay the price and do it right. And get those braided throw-rugs (with non-slip backing so you don't inintentionally go skiing)
However if fibrous cement were possible. and somehow could be cushioned by adding some other ingedients with a little give, colored and or patterned it might prove very exciting for groundfloor considerations. HMM...is that possible?
EXPERT: Yup. The Steen or Swearingen earthen floors are softer-feeling than wood, wear well, are easily repaired or replaced. Enjoy the luxury of Cordovan leather floors without the cost.
Wouldn't it be possible to build our own and save 5$ a block? Tiv, Gene, know of any formula for taking REAL ADOBE SOIL which is gummy, adding some concrete type product that is cheap to purchase by the truckload...and making a block which would either dry stack or mortar up and be strong. Any files out there, recipes for making our own HOMEY looking, rustic blocks out of clay soil?
EXPERT: if by "gummy", you mean clay, cheap lime is a better binder than Portland. Portland is more effective with clean, sharp sand and gravel. There's lots of ways to make adobe brick or formed walls, and any of them good enough if you have a wide roof overhang (which you should have anyway). You can "puddle" brick or a wall, add chopped straw for lighter weight and more strength.
Buy the Ken Kern book, "The Owner Built Home"---your best builders' library investment.
My favorite website on your particular question of numerous specialty adobe mixes is gone. Try googling the words ‘adobe mix’ http://shell.rmi.net/~adobeman/index.html (this is an 8 hour video on all phases of making and using adobe brick)---and any book by Paul Graham McHenry will be of great help.
(pumice, clay, bitumil (asphalt emulsion) makes a great adobe brick)
(and don't forget mud floors---a
favorite of mine)
(Canelo project---note the straw brick
and two-layered Carrizo (straw with light clay and perlite slip) with 3
inches of concrete over it in a vaulted roof.)
http://www.zetatalk.com/shelter/tshlt04c.htm (adobe recipe)
(adobe brickmaking in 1940 New
(preservation of historic
adobe buildings---and description of original processes)
(simple local materials
transformed into a work of art---the adobe, viga and latia way)
(Australian introduction of
asphalt emulsion in South Africa adobe brick)
The Wood Burning Adobe Barbecue
By AZ rancher, Boyd Crick
This adobe barbecue features a wood heated oven which is large enough to hold a turkey pan. The adobe fire box and main body of this barbecue can provide the grommet cook with any style of cooked meat: from steamy pit roasted to smoked (for authentic machaca). The choice is yours. This versatile barbecue also allows for regular up-draft cooking on wood or charcoal. (After three years of using mine, I find that I usually just put some charcoal in the built in hibachi and barbecue on it). I only roast on special occasions. The oven cooks a turkey in the same time as a regular oven. Do not be fooled by the slightly pink color of the meat. Smoked meat will give this appearance. Of course how long you cook it is up to you--only you. Do not let a committee help you.
The inside of the adobe fire box and heat vents will harden with use, unlike concrete which will only get soft when it has been heated. Also the adobe is easier to shape than fire bricks and can be formed into pleasing and functional shapes. Furthermore the adobe can always be altered or added on to. If you have ever tried to add new concrete to concrete which is already cured, you will know that it doesn't work well--even if you use the white concrete adhesive form the lumber yard. However, unfired adobe is not water-proof so some precautions must be taken.
The first precaution is the masonry base. Just like a house, the barbecue needs a masonry base because adobe will not support much weight when it is really wet through and through. The masonry base keeps the adobe elevated where it will not stand in water. You should consider the drainage of your yard when you locate your barbecue. The other necessity is a patio roof or colored stucco, or both. The patio roof is the most effective way of keeping the rain from gradually eroding your barbecue. If stucco is used, one must decide whether to use crack-control strips (lumber yard)--the barbecue will expand with heat--just enough to crack the stucco. I rather like the cracks as they make it look rustic. You can let the cracks develop and then just fill then with flexible tile grout. My choice was to just let the barbecue age a few years then build a roof over it. This way it looks like an Indian ruin which has been preserved. The look is just right for my yard. You can also whitewash the barbecue with quicklime and water. Ancient peoples kept their adobe structures protected by regular whitewashing. (A little red iron oxide or stucco coloring can be used for color). Some building codes require that houses built of adobe are really bitadobe. This means that a small amount of asphalt oil is added to the mixture to improve water resistance. I do not recommend this type of adobe for a barbecue because I think it would make the meat taste weird. ( would also caution against burning much pine or pitch pine for the same reason. Mesquite, Oak, other hard woods and prunings from nut or fruit trees work best. Even mulberry and hackberry work. )
Take time to think about work surfaces, sinks, storage and such things before you start. It always pays to spend plenty of time planning. Most of all, think and re-think about where you want to place your barbecue. If you have a portable barbecue you can test out parts of the yard before you commit to a location. Remember, you may even want to build a roof over it (make it tall enough or vented)
My barbecue is built on a concrete slab which is at least 6'x8' and 3" thick. If you already have a good patio you can skip part #1. If you live where it gets really cold, you should build your barbecue on a deep footing so ice cannot form between the slab and the base of the barbecue. If are careful when you finish the slab, you can make sure that it drains away from the barbecue. (See illustration #1 the basic concept of the updraft barbecue).
#(1). Be sure to prepare the sub-grade as necessary depending on the site. I use 6" of sub-grade. This means that you need a rectangular excavation at least six feet wide, eight feet long and nine inches deep. The first six inches of the excavation is filled with sub-grade. Contractors use stuff called ABC which is a compressible mixture of gravel, sand, and silt. They pack it with a pneumatic tamper or a special tractor roller. I use rammed concrete. Mix about three parts gravel + two parts sand (sub-grade sand does not need to be perfect) and one-half part Portland cement. Add ONLY enough water to dampen the mix. The trick here is to pack the crumbly mix with wooden tamps, or get your friends to stomp on it as it is added to the hole. COMPRESSION is the key and fluid mix will not compress. After all the sub-grade is in you can start pouring the slab. If you want to pour the slab later, be sure to sprinkle the rammed sub-grade as soon as you have packed it in. Sprinkle it every thirty minutes for about two hours, then cover it with water. Keep it wet until you pour the concrete. This sub-grade tends to suck the water out of concrete. Which is why I like to get the concrete poured before the sub-grade cures. If you want your slab to be elevated you can use more sub-grade and build a form for the concrete. The form can be made of oiled 2x4s. The form is supported with wooden or metal stakes inside and out. Earth from the excavation can be packed against the outside of the form. The wet concrete you will fill the form with is heavy and will exert pressure on your form. You should use a concrete mixer so the form can be filled quickly. For the slab, use just enough water to make the mix flow in the mixer. I start with a mixture of 2 parts pea gravel+1 part sand + 1 part cement. I fill the form evenly across the bottom. When I get close to the top, I use equal parts sand, pea gravel, and cement. This makes it easier to knock the gravel down below the surface (the end of a good rock rake will suffice if you do not have a tamper). You can strike off the concrete with a 2x4 which is worked across the form from one end to the other (get a helper to work the other end and use a sawing motion ) and finish it as much as you like. Obviously, most of your slab will be under the barbecue anyway. I like to add some extra concrete to the middle and work it with a finishing trowel so that the middle is raised slightly. Water should drain away from the barbecue base although it is also masonry.
Be sure to have plenty of help when you pour the slab. It takes at least one person to run the mixer, and one person to spread and pack the concrete. Otherwise, the concrete in the form might harden before you can spread it out and pack it down.
If all this seems like too much, you can just get some concrete blocks or large granite rocks to build your barbecue on. The idea is to keep the adobe elevated from rain water on the ground. I just built enough slab for my barbecue--then added other sections gradually to make a patio.
All concrete must be kept WET and cool. Depending on the weather, it will take about 4 weeks to cure the slab--the slower, the better. I use wet blankets and straw to keep concrete wet and cool. Remember, concrete gets hard because some of the water in the mix combines with the cement to form hard crystals. If the concrete is allowed to dry out before it is finished forming the crystals, it will just crumble. This is why concrete gets crumbly after it is exposed to too much heat. When the chemical water is driven out of the hydrate crystals, the concrete is ruined. On the other hand, adobe gets hard when it dries out. The clay in the mixture gets harder when it is dry. The silt and sand just reduce the shrinkage enough to prevent cracking. When heated, the adobe just gets harder.
A word or two about cement stabilized adobe. Rammed earth is a sandy soil which is stabilized by the addition of a little Portland cement. It gets its hardness by virtue of compression. (It can even be water proof). The catch is that you need really strong forms to withstand the pressure. DO NOT add Portland cement to your adobe. Rammed earth is packed into place as soon as it is mixed. However, your adobe will be added gradually. If you mix quicklime or cement to your adobe you will end up with a pile of hard mud which you cannot use. If you try to re-wet or reuse this stuff, it will just crumble. That is why you will see a good brick or stone mason really cleaning the old mortar out of the mixing boat between batches. You can add water to mortar only once. After that it must be dumped. The old mix will contaminate any new mix. Moreover, it will absolutely ruin your adobe. There it is: Masonry or concrete to protect against water and adobe to withstand heat and sculpt or form with. Remember, you need helpers--not a committee of "experts."
#2.When the slab is cured, construction of the actual barbecue can begin. The first step is to draw a rectangle on the slab where the barbecue goes. .Make it at least 6" oversized so you can see the lines. After the mortar is down. I use colored chalk. At this point you could use blocks or even fire bricks, but I have access to good hard granite rocks (actually they are Pinal Schist). You need good hard stones without cracks. Sedimentary rocks like sandstone or slate will also work. Just be sure to use rocks which are used for building or paving. Do not try untested rocks. In my area, one can get permission from the forest service to get rocks by the road-side in parts of the public lands. If you have a truck, it can make a fun outing.
The rocks should be soaked in water for at least 48 hours, then scrubbed with a stiff brush and a little dish soap. Rinse them well. This will insure that the rocks stick well and prevent them from sucking the vital water out of the mortar. Take your time and dry fit the rocks before you mix the mortar. Then remove the rocks from the slab and mix some mortar. You can then replace the rocks on the bed of mortar. I mix one part Portland cement to three parts coarse sand with the minimum amount of water. If your rocks are smooth, one-fourth part of quicklime can be added to make the mortar sticky. Hand mixing requires less water than the concrete mixer and is therefor preferable. If you must use a machine, A mortar mixer is better than a concrete mixer. Good mortar is just too sticky in a concrete mixer. I mix by hand in a wheelbarrow. The mortar must be stiff enough to stand at least 6" tall when shoveled onto the slab. Contractors use a slump test. The idea is that if you mix it long enough, it will be able to stand vertically instead of just running. Do not add excess water. It is best if you add water gradually as you mix. I know people who make a slurry and then add dry ingredients to stiffen the mix. While this will work, your mix will be better if you avoid it (more chemical reasons). Also this mortar can be colored by the addition of stucco color which you can get at a lumber yard.
The rocks can be placed in the perimeter. They should have at least 3" of mortar under them, and 2-3" of mortar between them. Once the perimeter is complete, the inside can be filled with rocks and mortar. This masonry base must be at least 12" high around the perimeter and elsewhere except beneath the fire box. Leave room for the 4 to 6" of adobe which insulates the masonry form the bottom of the fire box. Remember, heat is not good for cement. Also, don't allow any rocks to project up past the mortar (see illustration#2)
#3. While waiting for the base to cure, you can begin working on your adobe. Traditionally, adobe was very practical stuff. It was made from the earth which was dug-up as a result of digging a basement or other necessary hole. The fortunate builder found layers of clay, silt, and sand as he dug. The separate earth components were placed in separate piles. These piles would provide the equal parts of sand, silt, and clay which form the optional mix. When the best proportions are not present, straw or cow manure is used to bind the mix. I do not resort this method unless I want light-weight adobe. Bugs and small creatures like to make earth sheltered homes in the straw type adobe. If you use this method, make sure the barbecue is in a place where bugs will not bug you. You can make test batches of this type of mixture and test it by: Dropping, crushing, and heating it. I used equal parts of red clay, coarse sand, and silt. This is the strongest mixture. If you have a truck, you can haul the ingredients you need. Contractors and road crews often dig-up good clay. Sand and silt can be found in dry washes. Screen out rocks and clay lumps. You will probably find that your sand contains some silt, or that the clay (not always red) contains some sand ect. The way to sort this out is with the settlement test. Take each of your ingredients and dry it out completely. The clay should be broken into small pieces and dried then crushed and dried more. Dry it in a warm oven if you have to, but keep it below 200 F or it will blow little bits of clay all over the place. Do not even think about drying it in a microwave. Next get a jar with straight sides --like a graduated cylinder. Put enough of the sample and water in the jar to fill it about 2/3 full. Next, shake it, let it sit, and shake it again. You will have to shake the clay sample over and over. When the sample has been completely mixed, let it sit on a level surface until it is completely settled. The different components will settle into distinct layers. The sand will fall to the bottom. The next layer will be the silt, and the top layer will be clay. Now you can figure out the portions you need to get equal parts. Write down the portions you try and give the mixture the settlement test. When you get equal parts, you will know what it takes to get equal parts of clay, silt and sand. Now you can use a shovel to measure out the adobe mix. Good adobe does not have to be perfect. Just remember, if it has too much clay it will shrink a lot when it dries and this can cause it to crack. On the other hand if it has too much silt or sand, it will tend to crumble. Furthermore, if you cannot get your sediment test to work (ie the sample jells and will not settle into layers, you probably have soluble salts in the soil. this soil can make good adobe, but you need to test it. You can make test blocks by packing the mud into a small form made of 2x4's. I once used soil with a little caliche (calcium carbonate) to build a very nice adobe fireplace. Once you become accustomed to your local ingredients you can do like the primitive people and just eyeball it. Where I live there is red clay with decomposing granite sand in it (its called adobe soil). I just mix it with about two parts of silty sand from a dry wash, and I have a very strong mixture.
Once you have your dry ingredients on hand and have a little experience with them, you are ready to start mixing mud. After your piles of ingredients are screened, they can be mixed with plenty of water in a mixing boat with a mixing hoe or it can be mixed in a bowl shaped hole with the feet. Some people buy beer or sodas and invite some friends to stomp around in the mud. After the mud is completely mixed, take it out and pile it up for a while to cure. After it has dried and stiffened up a bit it will be easy to handle and pile on the base. I start a new batch soaking in the hole while the previous batch is curing on a slab. The adobe can be kept fresh by covering it with a plastic drop cloth.
After the base has about four inches of adobe on it, it is time to start building the sand form. You need damp sand which is sticky enough to hold its shape. Some adobe can be added to accomplish this. (Some artists use a few drops of the previously mentioned concrete adhesive in a shovel full of sand, but do not over do). Do not add more adobe than is needed, because you will have to dig the sand form out after the adobe has hardened. The sand should handle like sand-castle sand. The sand will form the needed cavities in the barbecue. The outside perimeter can be supported by forms made of concrete blocks and dirt stacked around it anything heavy. Don't worry about the outside much. It can be sculpted into shape after the main mass is built. In fact even the fire-box and the heat channels can be carved into it after the adobe mass is built, however that is the hard way. The beauty of this method is that the sticky sand is shaped to create the fire box and the heat vents. When the adobe is cured, the sand is removed and the inner parts are finished. once you get used to visualizing the empty spaces as solid, you can use this method to make neat sculptural stuff with adobe and concrete
If desired, this barbecue can be built without the oven or it can be added later. The great thing about adobe is that one can always alter it. I like the option of building in stages as I get the time and money. I can upgrade and use my barbecue at the same time. Your choice is not " set in stone," just be sure to leave plenty of room for possible expansion .
The oven arch can be built of light-weight adobe. This can be made by adding
straw, wood chips, cow manure, or vermiculite to the basic mix. (Adobe mixed
with some vermiculite can also be used to line the bottom of the fire-box for
better heating). However, I prefer to use fired bricks for this part. I was
fortunate to locate some good bricks from a quicklime plant. These are safe to
use because they have only been used to heat calcium carbonate into calcium
oxide. Never use bricks which have been used for smelting or other questionable
purposes--they absorb impurities. New clay arch-bricks can be purchased. Or
fired adobes can be bought inexpensively. If you want to make fired adobes for
the oven arch, you can mix two parts clay, one part silica sand (#30 lumber
yard) and one part wood chips or vermiculite. I use equal parts kaolin and ball
clay (pottery supply) for my clay--if you use adobe clay, you should test fire
a brick to be sure it will fire good. To fire the bricks, you will need a large
kiln or a place where you can stack a "clutch" and make a lot of
smoke. The bricks are stacked on edge with wood between them the whole thing is
fired like a bon fire. The bricks in the middle get hotter than the ones at the
perimeter. Instructions for firing the bricks can be found in a book called
"Pioneer Pottery" by Cardew. It is a common book should be in your local
Like the arch for the fire box, the arch for the oven can be made with a sand form. An arch this big will need some support. You can simply place a piece of 1/2 inch plyboard at the front and back of the arch. These pieces can be supported by the use of 2x4's which are angle cut at the ends and staked at the ground. Use nails to hold them at the pylwood (fig 5). This form can be covered with lightweight adobe or straight bricks which are adjusted with mud (see fig 3-b). After it dries awhile you can take the sand out.
Arch method #2
I do not recommend this method for this project, but I have included it for those who may need it. One easy way to use either fired or unfired adobes is to build a bent plywood arch form. This will make a barrel arch. take a piece of 1/4 inch pylwood and bend it so that the ends can be screwed onto the ends of two 2x4s The bricks are placed edge-wise. The mortar between the bricks will adjust the shape to the arch. In other words the mortar will be wedge shaped. This way you need not make arch bricks. You only need a block mold or a gang mold made of 2x4's to make the bricks. The gang mold looks like a ladder but the 2x4's are on edge. Use cement mortar for fired bricks, and adobe mortar for unfired adobes. The same adobe which is used for the bricks should be used for the mortar. If you choose this method, make your oven arch form first then build the adobe base to fit it. I test it with a turkey pan with the lid on.
One neat way to design a template for an arch is to hang a limp small-link chain in front of a piece of card board. First, draw a line which is as long as the base of the arch. Next, find the middle of this line and use a square to make a perpendicular line from the center point. This is the center line. This center line is as long an the arch is high. Next, hang the cardboard upside down on a wall and use a plumb bob to get the center line vertical. Now you can secure the cardboard and recheck for plumb. Next drive a small nail at each end to the base line. Now you can hang a limp-small-link chain from the nails. let it hang down to the end of the center line. Now you can make some marks or trace out the line made by the hanging chain. You now have a cantonary arch. Gravity will make it for you. If you cut out the arch, the remaining template can be dragged over the sand arch to check it.
the front and back of the oven arch. make a cardboard template of the finished
arch and lay it on a 3-1/2 inch slab of firm brick clay.
Cut out the form with an old butcher knife. Then cut the slab into bricks these can be fired. I glazed and fired mine in a small kiln. (If you know a potter, you have it made). If you fire bricks, be sure you dry them completely before firing. The wood chips and or vermiculite will help prevent them from exploding as the steam escapes. The bricks in the back of the oven part were mortared in except three at the top. They are removed during cooking for smoke draft. If you do not want to fire them, you can just stick them with adobe. The bricks in the front are left loose, I just remove them, put the meat in and restack them for cooking. This setup drafts perfectly and no chimney is needed--if you follow the diagrams. You may want to build an oven door if you want to cook bread. (I did not want to change the looks with iron parts). You can also just stack light weight adobe bricks and fresh lightweight mud in front after you put the meat into the oven. This provides the steamy atmosphere needed for pit roasting. It may be a bit of trouble, but it is way easier to close the oven with fresh adobe than it is to dig a hole in the ground for pit roasting. Be sure to leave a good ledge at the front of the oven so you can use a double course of bricks this will better insulate the oven. In designing this barbecue, I used my years of experience as a kiln builder to calculate the size and shape of the fire box and the heat chambers. You will actually see the fire drafting horizontally into the chambers. The oven will heat up quickly if you follow the plan for the innards. Do with the outside as you will. Do remember to let the barbecue dry good and break in with a small fire at first. And remember it is normal for it to crack a little.
Good luck, and if you need advise just write me or send me an email.
Boyd Crick firstname.lastname@example.org
RT 2 box 78
Globe, AZ 85501
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