Ferrocement Educational Forum
Welcome, Guest. Please login or register.
October 25, 2014, 05:30:11 PM

Login with username, password and session length
Search:     Advanced search
Welcome to the NEW Ferrocement Discussion Forum
2699 Posts in 407 Topics by 572 Members
Latest Member: Ross
* Home Help Search Calendar ArchivesFEN Home Login Register
Ferrocement Educational Forum  |  Related Discussions  |  Lightweight Concrete, Papercrete, EPS, etc.  |  Topic: cement slurry coated chopped straw mix for walls « previous next »
Pages: [1] 2 Print
Author Topic: cement slurry coated chopped straw mix for walls  (Read 7405 times)
Ron Davis
Full Member
***
Posts: 15


« on: August 13, 2010, 03:58:57 PM »

 Hi FerroFriends,
   
   For some time I have been thinking about a low cost building material produced from chopped straw mixed with a cement slurry of some kind. I envision that the straw pieces would be lightly but completely coated with this slurry.
The structural strength would be a result of the slurry  connections where the straws crossed each other.
 
 IDEALLY:

The resulting material would be mostly air.
It could be placed between lightweight form for walls.
It could be rapidly curing so forms could be reused in a short time.
It could be cut with  a saw.
It would be bug and fireproof.
It would have good insulating qualities.
It would have a good strength to weight ratio.
It would be very low cost.
  Has anyone tried this?
 Any comments?
 
  All the best, Ron Davis
 watermotor.net
Logged
Steve Millward
Full Member
***
Posts: 16


« Reply #1 on: August 14, 2010, 12:58:06 PM »

Hi Ron,
     Dr. Richard Austin (who apparently now goes by a new Indian sounding name) has done quite a bit of research in this area.  You might want to check this out.   http://PlanetaryRenewal.org/ipr/insulation.html

Also, check out the rest of his website - you might find out something useful.

Cheers

Steve Millward
Logged
Ron Davis
Full Member
***
Posts: 15


« Reply #2 on: August 16, 2010, 10:58:45 AM »

Richard:
Thank You very much for sending me to that site. It had a very simple well thought out method of coating the chopped straw with a clay slurry.

Just spread it out, spray it with liquid clay, rake it up and put it in the form.  WOW!

I wonder what would happen if there were about ten percent cement mixed with the clay?
 Wouldn't that make it much stronger and more waterproof?

  Would it be a good idea to mix an hardening accelerator with the clay/cement slurry mix to make it possible to remove and reuse the form quicker?

   Ron Davis
  La Paz, Bolivia
  Watermotor at watermotor.net
Logged
Ron Davis
Full Member
***
Posts: 15


« Reply #3 on: August 17, 2010, 02:11:00 PM »


 

 I took another look at the site Richard sent describing chopped straw with a very light coating of a clay slurry as a building material.

 http://PlanetaryRenewal.org/ipr/insulation.html

     Does anyone know of actual examples of this type of construction?
     I think the principle is very good.

 Ron Davis
   watermotor.net

   
Logged
Chris Glasspool
global Moderator 2
Sr. Member
*****
Posts: 498



« Reply #4 on: August 17, 2010, 04:00:14 PM »

Hi Ron,

I think you might be interested in the computer search words: cob construction. Cob is an ancient technique of building free form structures of clay and straw (and other tensile organic fibers - hair, pine needles, etc.) It seems to be getting a renewed interest, with of course some people updating the methods, and materials.

Cement does not make a good mix with clay, though Ken Kern wrote about using asphalt emulsion with clay. There has been a lot of research on cement mixed with sandy soil to a ratio of 10% cement, and not more than I think around 15% clay, with no organic matter.  I have heard of this being called soil-crete, but it may have other names too. The military has used a method of mixing 10% cement into a bare dirt strip with big tillers, and heavy rolling, and dampening to create very quick - inexpensive air strips that have then taken heavy use as a runway with heavy aircraft going in and out. Some building has been done with tamping this material into forms to create good looking earthen walls.
- chris
Logged
daurtanyn
Full Member
***
Posts: 28



« Reply #5 on: August 22, 2010, 10:43:20 AM »

Clay can make a good combination with cement when it has been calcined. 

Calcined Kaoline clay, or MetaKaolin is a widely used and available mineral admixture for concrete which can, because it is pozzolanic, replace a portion of the cement.

And, because the temperature needed to create the metakaolin is much lower (800-900C) than the temperature needed to make cement clinker (2,500C) there is a real environmental benefit.   Additionally, you save the CO2 outgassing from the clinker creation.

Hubert
Logged
Ron Davis
Full Member
***
Posts: 15


« Reply #6 on: August 23, 2010, 02:41:10 PM »


  Chris,
 Its good to hear from you. Interesting comments and suggestions.  And thank you Hubert for your input.
  I think I will have to experiment. What do you think of using a pure cement slurry to spray on the chopped straw?
The material I have in mind would be nearly all straw and as little cement slurry as possible.

   Can you think of any common material that would possibly help the cement slurry to stick evenly to the straw?
  Something from Sika? Just guessing.
Best,
Ron Davis
Logged
Jah3-Maniac
Newbie
*
Posts: 4


« Reply #7 on: September 02, 2010, 05:09:48 PM »

Chris,

It sounds to me like what you are talking about is "latex concrete" as recommended in 'Latex Concrete Habitat' (Albert Knott and George Nez).

I quote "A common slurry coat mix is 1.5 to 2 parts cement to 1 part of liquid latex. The slurry is mixed to a lump-free, creamy consistency. A slurry coat filler of fine screened sand can be added if desired, using a sand-to-cement ratio of up to 1."

The easiest form of liquid latex to find is common and garden emulsion paint. This slurry will coat and bond to a pane of glass so it will coat straw!

Paul
Logged
Chris Glasspool
global Moderator 2
Sr. Member
*****
Posts: 498



« Reply #8 on: September 06, 2010, 04:43:04 PM »

Paul,

I wasn't talking about Latex-crete, but maybe that's another option.

Ron is out with the Campasinos of Bolivia, where it is assumed that good quality materials are difficult to find, and/or expensive, and he has been trying to help things out there for quite awhile, so I grab at solutions for his questions that might fit the scene. Ron comes up with some very innovative solutions to many of the challenges he runs into.

I'm not actually enamored with using asphaltum for very much, but the author of owner built homes - Ken Kern sure was, and Ron does have that petrol option, where as I don't know what quality, availability, and price he has out in the sticks of Bolivia for cement in comparison to asphaltum.

It isn't easy to pitch ideas from this far away, maybe Latex Paints added to cement would actually be a good fit there?

- chris
Logged
Jah3-Maniac
Newbie
*
Posts: 4


« Reply #9 on: September 09, 2010, 06:40:39 AM »

Chris,

Petrol ... Hmm! ... How about emulsified asphalt then?

I don't remember where this was recommended but I have seen it proposed as an additive for clay slurries.

Paul
Logged
drginter
Full Member
***
Posts: 35


« Reply #10 on: September 09, 2010, 08:28:28 AM »

what exactly is "emulsified asphalt" anyway?

i've heard of it from Ken Kern's book, but never really understood what it is.

dennis
Logged
Chris Glasspool
global Moderator 2
Sr. Member
*****
Posts: 498



« Reply #11 on: September 09, 2010, 11:23:48 AM »

Dennis,

It is the left overs form oil processing (tar), and it is mixed (emulsified) with water in a very complicated manner since oil and water do not mix together easily. It requires a heated industrial soap to be injected into a high sheer mixer with the oil , and water. The temperature, and equipment, and ratios have to be perfect, or the process wont work well. Of course you don't make it, you buy it by  the drum.

Exactly how you use it I don't know. I imagine my prejudices towards using petrol chemical to stabilize my owner built house made me gloss over Ken Kern's advice on the subject; though Ken Kern was a smart guy, and I probably should of payed more attention. - chris
Logged
Colin King
Sr. Member
****
Posts: 105



« Reply #12 on: September 09, 2010, 04:13:57 PM »


Chris and all you others,  Thanks for the explanation of how oil and water get mixed.  I always wondered.  I saw it used in mixing the clay "mortar" to set adobe blocks.  The house was being built on the eastern slope of the hills behind the University at Berkeley.  The emulsified asphalt was mixed in with the water to water-proof the mortar.  This was in 1949-50 in a pricey neighborhood so I think there was an engineering stamp on the plans.  Kern has a chapter on composite materials that still bears reading.  Colin
Logged
Ron Davis
Full Member
***
Posts: 15


« Reply #13 on: November 08, 2010, 11:14:00 AM »


   What I was inspired by was these 500 to 1000 year old mud and straw structures, called chulpas,  commonly found  on the Bolivian highlands (13,000ft) and which are often still  in good condition. These are usually 2 to three meters square and three meters high,and  hollow inside to contain human remains. There is no roof, per se. It is just solid above (These can be seen on Google Images, search chulpas bolivia) No apparent foundations either.
The straw, a tough local grass, forms a very high percentage of the material. I think the straw wicks away moisture so it never goes soggy. The matrix, a type of mud, is extremely hard, almost like low grade cement. Perhaps they had an additive of some sort. Perhaps vegetable.
  I was wondering if  10% portland  cement added to ordinary soil would achieve something similar today. This mix is sometimes used in cinva ram earthen blocks.

 Ron Davis
 watermotor.net
 watermotorstory.blogspot.com
 watermotorturbine on Youtube
Logged
Steve Millward
Full Member
***
Posts: 16


« Reply #14 on: November 08, 2010, 12:39:09 PM »

Hi Ron,
     You might get some ideas from the Cast Earth website.  www.castearth.com  They cast clay soil into forms, much like concrete.  They use a calcined gypsum additive.  They also refer to certain mystery ingredients for accelerating and retarding the set.  I believe the main mystery ingredient is lignosulphate, which is derived from trees in the pulp mills.  It retards the mix and adds a lot of strength to the finished product.  I believe a man named Pliny Fisk used lignosulphate mixed with earth to cast a poor man's woodburning stove.  Sodium silicate (waterglass) is also used as an accelerator and for waterproofing.  Anyhow, checking out the website might give you some ideas.

Good luck

Steve Millward
Logged
Pages: [1] 2 Print 
Ferrocement Educational Forum  |  Related Discussions  |  Lightweight Concrete, Papercrete, EPS, etc.  |  Topic: cement slurry coated chopped straw mix for walls « previous next »
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.13 | SMF © 2006-2008, Simple Machines LLC Valid XHTML 1.0! Valid CSS!