My miscrete experiment

Discussion in 'Designing, building, making and powering your life' started by antonius, Aug 1, 2017.

  1. antonius

    antonius Member

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    Although hemp bales are to be found in ireland they are all imported from europe and the uk, prices per bale have varied from 16 euro to 22 euro and while it is legally possible to grow a hemp crop here ,the terms and conditions imposed are hard to meet ,then as far as i can establish there is no processing plant to remove the fiber layer. The shed i want to insulate is timber framed --untreated -- and has a corrugated sheet iron skin , by my rough calculations i would need to use 400 bales so costs for using hemp soon put this project down as a dream. Then after speaking to a few people with hempcrete experience i was advised not to try and use anything else as a substitute , but all of this well meaning and help full advise centers around hemp shiv as the only plant based material with a very high silica content , this element is reported to be responsible for the lime binder being able to react and start its set up process. Lots of reading later and some of this information that is reported as fact seems to be a little mis- understood well by me at least, hemp plant does not have the highest silica percentage content, that first prize goes to most of the cerial based stalk type plants with rice hull/husks being the highest. Some further reading and sifting out of facts later and i purchased 10 bales of miscanthus grass to do my own test batches and blocks of m/crete , settling on a recipe or formula was not easy as each internet sourced formula and mix was different , but a study done in sweden on hemp binder and ratios gave me a starting point .I first mixed up each batch by hand and found the easier way was to use a pitchfork and an old bathtub , not as heavy on the back as trying to do this with a shovel and the plug hole meant if i had to much water some could be leaked out.
     
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  2. antonius

    antonius Member

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    My first 3 batches were failures , i failed to measure and control the ratio of the 4 ingredients - 1st too dry and not enough binder -2nd to much hydrated lime , 3rd too much water - , each failed to set up so were put aside then spread out to dry on the shed floor and crumbled up into my latest mixes. I found trying to mix small amounts too much messing around with bucket and jugs and then weighing it up was slow and boring , and with the 400 bales i now have in my shed this process would take a very long time. So i now use this , it knocks out a 100 liter batch for now as the belt drive is slipping and needs some further tinkering or going to chain drive would solve that problem mgrassbuild 007.JPG mgrassbuild 016.JPG mgrassbuild 015.JPG
     

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  3. antonius

    antonius Member

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    Yes it does look a bit rough and ready , its made from my scrap pile and scrounged up parts with some small made up bits by a local engineering guy , turns at 45 rpm , no major design or CAD envolved and mostly "lets just give it a try" , not everyone would have access to a telehandler--i am a one man operation and would be lost with out it ,if anyone wants more info just ask .The m/crete -ing is going well and sets up with out problems i keep a little lump of it next to the computer as an unexpected bonus--its smells nice --has a faint vanilla aroma to it , a reaction of the alkaline binder on the lignin i think. My formula for mixing is based on the percentages , 19% grass 31% binder 50% water , there is another one for a roof insulation version which i have not tried out at 21% grass 28% binder and 50% water. these are by weight and not by volume or parts as most recipes are using , my binder is 70% hydrated lime and 30% hydraulic lime --nothing else --no sand no clay no other chems. My hydraulic lime is NHL5 type but i will be trying out a batch of lower grade to bring my costs down a bit , this m/crete is for insulation only no structual purpose at all. Again anyone wants more explanation or reasons as why i believe miscanthus can be used , just ask , and no i dont think its a replacement for hemp--nothing comes close to the usefullness of that crop plant, cheers
     
  4. Sono Io

    Sono Io New Member

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    Excuse my ignorance but just what are you trying to make and what is the criteria selected to make it
     
  5. antonius

    antonius Member

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    Its a type of building material used for insulation ,with a lower carbon footprint and less toxic to the enviroment and a bit easier to work with . mgrassbuild 006.JPG
     
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  6. antonius

    antonius Member

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    Whilest looking at some ideas for a weed cutting rake , these leaf hand rakes caught my attention ---what if they were used to mix miscrete or h empcrete in the bathtub --adapt this idea to a pitchfork and become your own human powered mixer---a bit frightening --dont wear them with the neighbours watching ---get your self covered in a bit of lime dust and grass--and you will look like freddie kruger
     

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  7. Pop Alexandra

    Pop Alexandra New Member

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    Props to you. I'm curious how durable it is. What is the expected life span?
     
  8. antonius

    antonius Member

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    i would estimate it to be as durable as hempcrete, made by using the same binding material of lime --with the same method , other hemp substitutes like coir ,reed grass, rice stem and so on have been used in tests and found to be just as good , but are all local solutions to the lack of hemp in most countries .Its got to be used in the same way as hemp , its not load bearing and its not weatherproof on its own , yes i suppose if you built it into 600 mm wide walls they could be load carrying to some degree --but thats not its purpose.I am expecting this stuff to out live the iron cladding of the shed--provided its kept dry /weatherproof, it has no base sugars in it so has no feed value --does not attract insects or rodents -- to alkaline-- its fireproof past the industry standards-- which i tested out my self ---home diy style with blowtorch and firebrick oven and my watch -can recover from water ingress if allowed to dry out--so it will out do the current practice of dry lining , battens and fibreglass -rockwool i think. I am not an expert of course , and i have no commercial interests in this process--its all at my own risk and expense, cheers tony
     
  9. antonius

    antonius Member

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    there is a commercialized product made in the netherlands , from short chopped and sifted miscanthus grass added into concrete, intended for load bearing use and as a green alternative to fiber reinforced concrete --most are using glassfibre and similar manufactured fibers for this. Although this miscanthus is called elephant grass by some --its not the same plant--that does have a feed value --for animals ---miscanthus is a sterile hybrid(at the moment)--a designer grass you could say --selectively bred for fuel-- its original intention was to supply bio mass for furnaces in electrical generation --a drawback was its high silica ash content with low melting point --this forms globules in the airdraw grates --clogs up the system--it was rejected by all the furnace plants as the only way to use it requires adding lime power ,hardwoods or/and coal into the mix --to create a higher temperature burn --they figured it wasnt worth the extra expense. Its next touted use is for bio fuel--digesters -to convert its cellulose to starch for ethanol production--but i dont think thats going to happen over here. The parent species used to create miscanthus are being hybridized with the sugar cane(another hybrid itself of several species) to try and create a cold tolerant sugar cane of commercial value---so industry is hard at work to create a possible frankenstein that could become invasive if viable seed becomes a possible.
     
  10. mischief

    mischief Senior Member

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    Hi Antonius,
    I am puzzled by why you are trying to use concrete with your plant material to insulate walls.

    I have heard of people using straw that has had a slurry of clay worked through it to do this.
    One I remember hearing about- they worked the clay slurry on a tarpauline on the ground then pressed this into 'forms'- a frame that had been made to the dimensions of the walls. When these had dried enough to move into place, they were taken out of these and slipped into place between the studs.
    I dont recall what was used to keep them in place but I assume it would have been something like galvanised chicken mesh.
    This was then plastered to finish the walls.
     
  11. antonius

    antonius Member

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    sorry --i am not using concrete--i only mentioned a dutch company is making a form of concrete with added in miscanthus---not for insulation properties-- but for its reinforcement qualities of the plants stem fibers---its just a mention of this --as i have been told that you can not use miscanthus in any crete product -- "as it will rot away from the moisture" --well then someone(not me) has done a lot of research and development plus a patent application for nothing in that case --as well as launching their product on the european market. Lime mortar --is basicly what i am using with chopped miscanthus grass ---a version of hempcrete---generic trade or product description names for a mix of two types of lime with a plant based aggregate---the lime sets up by loss of moisture and exposure to carbon dioxide from our atmoshere -- and encapsulates the chopped grass----the calcified end product with lots of air gaps trapped inside. Concrete is cement based with crushed stone and sand--- and not an insulating material --much to dense --but it can be a mass heat storage material. The clay slip or slurry and straw is a different product and method --its like a quick version of cob---i have no experience of either --but they would seem to mostly use an internal woven wooden lath frame in stead of mesh to be eco friendly--which lime and cement products are not. The tarp mixer is also for eco friendly reasons --but not sure if it could work for miscrete--i am guilty of being lazy and mixing very batches of any thing by hand ---long ago --the novelty wore off --i use diesel power for that--yes its bad --so i plant trees to lessen the guilt and as atonement. I had looked at building a handpowered mixer for my purposes --i think it could be viable as miscrete or hempcrete require low speed mixing plus more of a folding over and into action so the binder does nt seperate from the grass ---but mines a one off adventure into this process so i wont go this route ---once my house is done --another project --my mixer will be recycled into something else or re purposed.
     
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  12. Brian Knight

    Brian Knight Junior Member

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    Love the innovative spirit! In our region, miscanthus is a major invasive so it would be great to see it torn out and repurposed for something useful, just don't spread the seeds in the process! Didn't realize it's also sold in bales?

    I question the R-value and performance claims of hempcrete and by extension, any composite wall material incorporating heavy amounts of lime. Pure wood is more thermal mass than insulation. By chopping cellulose up and surrounding it with lime, pushes the composite even further into thermal mass territory. Thermal mass performs best when completely surrounded by insulation. Using only thermal mass for exterior walls results in poor cold climate performance compared to a true insulation.

    Then there is the air-leak problem. I was brought in on a hempcrete wall, SIP roof project to help tighten up the SIP panels. I think it was one of the first hempcrete projects in the US. They were going for passive house certification but fell short because they couldn't meet the airtightness requirements. The project developers thought that air was leaking through the hempcrete, and apparently even three layers of plaster was not enough to make the walls airtight. I think the leakage could have been from other locations but these airtightness issues need to be addressed for good energy performance.

    Have you considered calling it Miscanthuscrete? I know it's more cumbersome but Miscrete has questionable marketing undertones. Reminds me of Chevy's "Nova" issues in spanish speaking countries.
     
    Last edited: Mar 7, 2018
  13. antonius

    antonius Member

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    hello, well i wont be marketing this --and the name is a bit tongue in cheek---i havent invented a new process here as it has been used/trialed before , and as i was told by some that it was not possible to use --as nothing else has the mythical level or content of silica as hemp --i thought i would give it a go as most of the material information and use on the net just seems to be a puke up of a few similar articles rehashed many times.The air leakage and thermal mass levels established by modern testing combined with modern industrial products ---which has gotten us where we are today with a legacy of some serious health issues .Has also given us several definitive expert solutions,answers and methods before and will no doubt give us many more again. As experienced here in ireland ,the current levels of insulation and heat loss were found to be a bit wrong , in the re-calculations and from data in everyday real life measurements , which the engineers of industry blamed on the incorrectly rated double glazing --so to get back to an accepted level --- so he/she can apply their signature to a form as an expert on this --again ----so we changed the way in how (the calculation) the glass is rated to improve its level for insulation ,So now a certificate can then be issued for how energy efficient your home is ,(for a fee of course ) , and everyone is happy and you can then avail of a grant to help pay for insulation work or sell your house to a prospective buyer --which is now a legal requirement . Air tight house issues arent my objective, i want a slightly more greener friendly ,diy approach, and possibly a much healthier product to live under , i cant speak for others --this is my folly ---and its my own highly opinionated opinion/s. The miscanthus currently grown in ireland is a hybrid of 2, maybe 3 species that sets infertile seed , it has to be propagated by root pieces --but nature is always scheming and cunning--so perhaps it might fool us again, my current conspiracy theory is based on the experiments of a sugarcane with miscanthus cross breeding program to create a cold tolerant cane sugar. Sugarcane its self is a hybrid of several grasses with a complex parentage so who knows what could happen . Irish miscanthus is an orphaned crop , cast aside by the same industry and green politcs that brought it in , its currently grown ,chipped and dried for pet and livestock bedding --horse breeders use it now as cheaper alternative to hemp --but it has to be de dusted to stop them coughing and sneezing--allergic horses ? or allergic breeders /owners i dont know --i didn t think to ask at the time of purchase
     
  14. antonius

    antonius Member

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    Had a slight set back , blew out a hydraulic hose on the machine ,its old and had worked a long life ,this meant wrestling out the ram and hose from inside the boom --had to dismantle the whole front off it , so painfully slow progress for a few weeks by hand mixing , but it meant time to ponder .Once up and running I tweaked the mixer drive belt mechanism a bit ,to get a better wrap around of the v- belts on the smaller drive pully ,this gives more drive friction so now i have able to mix a larger ( heavier) batch and do some catching up of lost time wise , now capable of a 200 liter by volume mix at a go--thats one 25kg bale chopped m/grass , one bag 25 kg hydrated lime , half a 25 kg bag hydraulic lime and 60 liters water in about 15 minutes--then 4 wheel barrow loads of it into place and start again .
     

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