Production

Fly Ash Additive to Brick mix

pregusay — Mon, 09 Sep 2019 04:56:41 +0000

Fly Ash Additive to Brick mix

Do you have any experience using the residue coming from coal fired electric plants?
We have an abundance of that here in our area which are being thrown away.
And one of the big power plants has allowed us to take it for FREE.

Would that be a suitable material to use in making the interlocking bricks?

If so, what would be a good ratio to start with?

pregusay Mon, 09/09/2019 - 11:56

That is a great question. …

That is a great question. Anything that we can do to reduce the use of OPC (Ordinary Portland Cement) is useful for the health of the planet. OPC production is very energy intensive and responsible for a lot of greenhouse gas emissions:

" A single industry accounts for around 5 percent of global carbon dioxide (CO2) emissions. It produces a material so ubiquitous it is nearly invisible: cement. It is the primary ingredient in concrete, which in turn forms the foundations and structures of the buildings we live and work in, and the roads and bridges we drive on. Concrete is the second most consumed substance on Earth after water. On average, each year, three tons of concrete are consumed by every person on the planet. "

https://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/

Using fly ash can partially replace OPC and still give a concrete that is as strong as one made with 100% OPC.

" Typically, 15 percent to 30 percent of the portland cement is replaced with fly ash . . . "

https://www.fhwa.dot.gov/pavement/recycling/fach03.cfm

There are many more advantages to fly ash concrete; read the linked article to learn more. The curing time needed might be longer.

It is also possible to make a lime-fly ash mix. You can test the strength of your blocks with a compression tester from the CVBT.

Just a couple of additional notes on mix design: Make your blocks as strong as necessary for the application. Interior walls might not need any stabilization (addition of cement). A one-story building doesn't need blocks as strong as for a two-story building. You might find some information on different standards in

Compressed Earth Blocks Standards (CDI - CRATerre-EAG, 1998, 144 p.)

We hope you'll post the results of your production and construction here.

If you have a lime soil, try…

If you have a lime soil, try making some fly ash - lime blocks. Test the strength and mass loss over time (wetting and drying cycles).

Production

Brick colors

Clovis — Wed, 20 Mar 2019 23:54:10 +0000

Brick colors

I was interesting in knowing what particular material is used to produce brick with different colors

Clovis Thu, 21/03/2019 - 06:54

Earth Block Colors

Basically blocks receive their color from the raw materials used. The base color is that of the soil used. A soil with an attractive color is valued by block producers. At the CVBT, we use a mix of pulverized nodular laterite, fine sand and a fine orange soil. We use the orange soil to get a more orange color in our block.

Powdered pigments, such as Bayer's iron oxide line, can also be used. Usually, the pigment is added as a percent of the weight of cement used. For red this is a maximum of about 5%. Adding more pigment than that will not make the block redder - it is already saturated.

Using gray cement or white cement has an affect on the color of the block. If you want red blocks, using gray cement is sufficient. If you want yellow blocks, it will help to use white cement (although it is much more expensive).

Walls can also be painted after a building is built. Use a breathable water-based acrylic paint. Sealing earth walls is not advisable - they need to breathe.

Production

Embodied energy of CEBs vs other brick alternatives

Dan — Sat, 23 Jun 2018 08:57:01 +0000

Embodied energy of CEBs vs other brick alternatives

Hi Geoffrey

any comments on the embodied energy of CEBs vs fired clay mix bricks or other traditional alternatives would be much appreciated!

Cheers,

Dan

Dan Sat, 23/06/2018 - 15:57

Comparison of Embodied Energy in Load Bearing Walls

That's great cheers Geoffrey!

Production

Stabilising/binding agents in CEBs; Portland cement and possible alternatives?

Dan — Fri, 22 Jun 2018 11:59:34 +0000

Stabilising/binding agents in CEBs; Portland cement and possible alternatives?

Hi Geoffrey,

Just after some more general information regarding CEBs, especially the ratio of cement needed as an admixture and the potential of other less CO2 intensive materials like RHA to be partial or full replacements as stabilising/binding agents?

Kind regards,
Dan

Dan Fri, 22/06/2018 - 18:59

Appropriate mixes for CEBs.

CEBs can be made with no cement. Unstabilized earth blocks can be used where they will not be subject to moisture. For stabilized blocks, a typical mix is 1:8 cement to aggregate. Leaner mixes can be used if a compression tester is available to verify strength. There are 3 standards: 1 MPa, 2 MPa and 3 Mpa compressive strength. At our Center we a use a mix of 1:11. 30% of the cement could be replaced with finely ground rice husk ash (RHA). Lime or lime/RHA can also be used as binders.

Production

Compression strength tests

T_Nhien — Thu, 14 Jun 2018 13:48:11 +0000

Compression strength tests

Dear Geoffrey,

do you know whether there is a lab/institute in Chiang Mai who can conduct compression strength tests for blocks?

thanks & best regards,
Nhien

T_Nhien Thu, 14/06/2018 - 20:48

Compression Strength Testing of Compressed Earth Blocks

It is appropriate to test the compressive strength of compressed earth blocks when they are to be used in load-bearing walls. In Thailand blocks are typically of sizes: 25 x 12.5 x 10 cm or 30 x 15 x 10 cm. They should be between 1 and 3 MPa strength after 28 days. At the CVBT we test our blocks at 7 days to 2 MPa because we want feedback for production sooner and for confidence.

Unfortunately, compressive strength testing equipment designed for standard 15 cm concrete cubes (typically having compressive strengths of 20 to 40 MPa) will not give meaningful readings in the much lower strength range of compressed earth blocks. The Center for Vocational Building Technology makes a Compression Tester, model CT5, that works well with compressed earth blocks.

Thank you for your reply…

Thank you for your reply. The blocks I want to test are lightweight insulating concrete and therefore are not intended as load-bearing wall. I am looking at compressive strength between 0.35-0.6 MPa (30/60days) for these blocks. Is It possible to accurately test these blocks with your CT5 for low compressive strength blocks?

Compressive Test Specimen Cross-Sectional Area

Compressive strength is Force / Area. The area in question is the net cross-sectional area of the specimen you are testing. The nominal area is the length multiplied by the width. From this subtract the area of vertical corner chamfers, vertical grooves and vertical internal cavities. We actually have a variation of the CT5 that we use to measure very low forces. I'm sure that we have, or can come up with, a configuration of equipment that can meet your needs. I'd like to know the dimensions of your block so that I can know which configuration you need.

Please understand that we it is appropriate to test blocks for compressive strength. If you are making panels then the characteristic that we need to be interested in is the tensile (aka, bending) strength. That requires a very different setup for testing.

Compressive Strength Test

I have already done the tensile test but would like to do compressive strength test as well. the current dimension of my blocks are 35 x 14 x 8 cm, however for the compression strength test I can make blocks of 30 x 15 x 10 to match with the size of your CT5. Thank you for your support.

The CT-5 can accommodate…

The CT-5 can accommodate blocks up to 47 cm long. It might be necessary to cut steel plates to support the block. 30 x 15 x 10 cm blocks are readily accommodated.

Production

Non-stabilized compressed earth blocks

jgarcias.cr — Fri, 21 Jul 2017 09:41:29 +0000

Non-stabilized compressed earth blocks

Hello dear Geoffrey
Before I began to make stabilized ICEBs, I wanted to check if the soil-sand mix was good for compression and had the right proportions of each component. So I pressed a few samples that appeared to be fine.

My question is, do they need to be somehow cured or treated in any special way to become useful for interior walls or other not heavy load applications?
Cheers,
Joaquin.

jgarcias.cr Fri, 21/07/2017 - 16:41

Resources for mix design.

Joaquin.

Let me refer you to GATE/Craterre's 2 excellent publications:

COMPRESSED EARTH. BLOCKS: MANUAL OF PRODUCTION by Vincent

Rigassi, CRATerre-EAG. Volume I. Manual of production

https://www.researchgate.net/file.PostFileLoader.html?id=5687a6447eddd3a22

08b45 75&assetKey=AS%3A313394584850433%401451730499973

COMPRESSED EARTH BLOCKS: MANUAL OF DESIGN AND.

CONSTRUCTION by Hubert Guillaud, Thierry Joffroy,. Pascal Odul, CRATerre-

EAG. Volume II.

http://www.rivendellvillage.org/Compressed_Earth_Block_Design_and_Construction.pdf

Your basic methodology is good: design your mix without a stabilizer first. Then stabilize if needed.

And yes, not all blocks need to be stabilized. Adobe is unstabilized and holds up a large load.

The thickness of the wall must be adjusted. Lower strength blocks mean a thicker wall is needed for the same load. You can test your block strength with a compression tester - the CVBT makes and sells them.

It is nice to render a nonstabilzed wall. Many renders are possible.

Here are a couple links:

http://www.solucionespracticas.org.pe/Descargar/619/5318

http://repository.upenn.edu/cgi/viewcontent.cgi?article=1382&context=hp_theses

Thanks for the question, I hope this is helpful.

Please post some photos of your construction.

We're working on upgrading our site. We have to wait for some bugs to be worked out of the software.

Respectfully yours,

Geoffrey Wheeler

CVBT, Udon Thani, THAILAND

Production

Reviving a Block maker

jak — Wed, 22 Jul 2015 12:38:26 +0000

Reviving a Block maker

Greetings from sunny Kenya!
have acquired two derelict block making machines (which were used for CEB a while back) These machines have been unused for over a decade and are rather stiff. am looking for assistance as to how to service these machines and how to get the 'ram' section to raise as it would when 'dispensing' the block
Any advice would be greatly appreciated!

jak Wed, 22/07/2015 - 19:38

renovating a block press

Jak,
Start with cleaning the machine. Some cement may have built up so some hard work is needed.
Then measure the box width and length in several places. This will tell you what size blocks you will get from the press.
Oil where appropriate.
The rest of the renovation basically depends on good thinking about the design and how to restore the functionality.
The CVBT renovates block presses. The CVBT's model BP6 is designed for serviceability and is readily renovated.

Production

Seminar/training opportunities in 2015

bambam — Wed, 17 Dec 2014 12:27:06 +0000

Seminar/training opportunities in 2015

Greetings Geoffrey,
Will you be holding any seminars or other training opportunities for production of and/or construction with ICEBs in 2015?
Thank you!

bambam Wed, 17/12/2014 - 19:27

Production

Proper mix for making good CEB

bambam — Wed, 19 Feb 2014 11:36:27 +0000

Proper mix for making good CEB

Thank you, Geoffrey for answering my many questions. I appreciate you sharing your knowledge and experience.
I've read that the ideal soil mix for solid CEBs is:
15% gravel (2-20 mm)
50% sand (0.06-2 mm)
15% silt
20% clay
What are your thoughts on this ideal mix?
Our soil here is very sand with measurable amounts of silt and clay in various places (up to 20% clay and silt combined).
The remander of our soil is fine sand (80%) with essentially no gravel. Is some gravel essential to a strong CEB block? What minimum percentage would you suggest? Gravel will have to be purchased whereas the sand and clay can be found in vllagers' fields.
Also, I am finding it a challenge to distinguish clay from silt. Do you have any suggestions for doing so?
Thank you!

bambam Wed, 19/02/2014 - 19:36

CEB mixes

When I train people to develop an ICEB mix I start with the materials that are available locally. In your case I'd make several different mixes with different ratios (by volume using a standard measuring bucket) of soils and/or sand. After I found a mix that had the characteristics I liked (color, texture, mixability, compressability, ejectability and liftability), I'd add different ratios of cement and make at least 20 blocks from the one I felt was most promising. After curing (7 to 28 days) I'd check the expansion by lining up 20 blocks (soaked for 48 hours) on a flat surface and measuring the theoretical versus the actual length.

The maximum particle size I like in a mix is about 9 mm; I usually use a maximum of about 4 mm. A 20 mm in a corner would be problematic. You can try this manual for soil surveying: http://www.cvbt-web.org/uploads/Pubs/Suitability%20of%20Local%20Soil%20for%20Cost%20Saving%20Construction%20Techniques.pdf It is new and perhaps in need of a little more editing but I think it is worthy of trying.
This one is good: http://www.cvbt-web.org/uploads/Pubs/Compressed%20earth%20blocks_Vol1.pdf
When learning something new, expect to learn a lot. Respectfully yours, Geoffrey

Production

2014 Training Opportunities

bambam — Fri, 31 Jan 2014 08:49:56 +0000

2014 Training Opportunities

Greetings from West Africa,
Do you have any training opportunities scheduled for 2014? especially in Rhino block production and construction?
Thank you.

bambam Fri, 31/01/2014 - 16:49

Hip hop training

Good question. Right now my hip is healing from a break in the femur bone. I still have 3 months to a year of convalescence. I will update my training schedule once I'm off of crutches. I'm hoping to begen a training schedule in June.

Production