Talk:Hempcrete

Sources

I'm having trouble finding reliable sources. Here are some sites I looked at, which may not be reliable:

• http://www.greenbuildingforum.co.uk/newforum/comments.php?DiscussionID=24
• http://www.constructireland.ie/articles/0215limehemp.php
• http://www.life.ca/nl/108/hemphouse.html
• http://www.natural-environment.com/blog/tag/hempcrete/

Bodhi.peace (talk) 04:22, 3 April 2008 (UTC)

• I personally think that if the sources you find seem to agree with each other, but don't seem to be directly quoting from each other, any would do. I linked the life.ca page, mainly because it seemed to cover the main points given in the stub so far. Trxi (talk) 03:55, 24 April 2008 (UTC)

More sources: http://www.bath.ac.uk/news/2009/04/08/hemp-houses/ and http://www.building.co.uk/story.asp?storycode=3125625 Smartse (talk) 21:42, 22 April 2009 (UTC)

Merge

I think that Cannabrick construction should be merged with this article as it seems to discuss the same topic. Smartse (talk) 21:39, 22 April 2009 (UTC)

I'll go ahead and redirect Cannabrick construction here - there doesn't seem to be any content in that article that isn't already here. Smartse (talk) 15:22, 28 August 2009 (UTC)

strength

It says that Hempcrete is up to seven times as strong as concrete, but does not say whether it means compressive strength or tensile strength, compressive strength being the important characteristic for concrete. —Preceding unsigned comment added by Carltheshivan (talk • contribs) 05:42, 28 August 2009 (UTC)

At the bottom of the article: http://www.inhabitat.com/2009/08/24/hemcrete-carbon-negative-hemp-walls-7x-stronger-than-concrete/ "Inhabitat >> Carbon Negative Hemp Walls are 7x Stronger than Concrete" there is a retraction from the article author Daniel Flahiff on August 25th, 2009 so I edited it out of this wikipedia article. Peace, rkmlai (talk) 06:05, 28 August 2009 (UTC)

The compressive strength is given in the reference as 1.0MPa. Typical concrete has a compressive strength of at least 30 MPa. —Preceding unsigned comment added by DBordello (talk • contribs) 20:47, 31 August 2009 (UTC)

Right. See [1], from American Lime Technology, which sells the stuff. It's not a structural material. It's more like wallboard. Here's a serious analysis of the material [2] but it's behind Elesvier's paywall. --John Nagle (talk) 06:24, 4 September 2010 (UTC)

See also "Sustainable Masonry Constructions: Initial structural tests of brick and hemp-lime composite walls". [3]. "Hemp-lime provides sufficient thermal resistance to act as the insulative material in a wall construction. Due to its low structural strength and stiffness it has not been used in structural applications to date. Results from preliminary testing suggest that combining structural brickwork with a hemp lime inner leaf can result in some structural benefits despite its low strength." Also, the suggestion in the article that hempcrete foundations would have advantages is uncited. The manufacturer of the product says it is inappropriate for below-ground applications. --John Nagle (talk) 17:14, 19 November 2010 (UTC)

Elasticity

It was added that hempcrete is "three times as elastic as traditional concrete".

The term "three times as elastic" does not make sense in this context. Is this referring to Young's Modulus? Stress at the proportional limit? Strain at the proportional limit? I have not seen the constitutive relationships for hempcrete analyzed. —Preceding unsigned comment added by DBordello (talk • contribs) 20:50, 31 August 2009 (UTC)

Carbon sequestration

The lime binder used in Hempcrete is made by heating calcium carbonate to 900 degrees Centigrade, which drives off CO₂ gas into the atmosphere. This same CO₂ gas is re-absorbed in the setting process, which converts the lime back to calcium carbonate. So the net effect on the CO₂ content of the atmosphere is zero. The claim that Hempcrete can equester CO₂ gas is pure balderdash.Koilon (talk) 03:03, 17 August 2010 (UTC)

I think you're missing the point somewhat, the CO₂ would be sequestered when the hemp grows in the first place and fixes carbon in the atmosphere. Smartse (talk) 11:34, 17 August 2010 (UTC)

Wilkinson 2009 questions carbon negativity (chapter 2.7 Hemp Lime - Carbon Negative?) source: Wilkinson (2009): A Study of the Moisture Buffering Potential of Hemp in Combination with Lime and Clay-Based Binders http://gse.cat.org.uk/public_downloads/research/hemp/Simon_Wilkinson.pdf 80.222.54.21 (talk) 15:35, 22 March 2012 (UTC)

Could someone do the math for the article regarding the carbon footprint? Some may not realize how the whole process works. — Preceding unsigned comment added by 174.126.76.44 (talk) 11:56, 24 January 2014 (UTC)

Durability

Discussed in the book: The Emperor Wears No Clothes by: Jack Herer

quote:

" Isochanvre, a rediscovered French building material made from hemp hurds mixed with lime, actually petrifies into a mineral state and lasts for many centuries. Archeologists have found a bridge in the south of France, from the Merovingian period (500–751 A.D.), built with this process. (See Chènevotte habitat of René, France in Appendix I.) "

source: http://www.jackherer.com/thebook/chapter-two/ — Preceding unsigned comment added by 50.93.56.54 (talk) 19:29, 29 May 2011 (UTC)

Much information from Jack Herer is bogus. Can you find some reference to that bridge? Searching only turns up references to promotional sites for hemp. --John Nagle (talk) 15:08, 1 July 2011 (UTC)

Dear John, here is an print reference: Chènevotte habitat of René, France in Appendix I. You can get an copy for 10 EUD from here: http://www.chanvre-info.ch/info/de/Isochanvre-Verkaufsinformation-nur.html — Preceding unsigned comment added by Tribble (talk • contribs) 18:11, 3 January 2014 (UTC)

You kind of beat me to it. When you, people, can't find proper information on a thing that is not in the English language sphere try using the language where it happens. If you do not know this language try another one that you know or ask a friend. You can also look at the left pane with languages which tells you in which language the same thing has an article on wikipedia. Contrary to popular belief, the left pane leads to the topic, not the main page for that language. Example: Someone recently wrote 'the zoo in Tblisi (where the hippo stood in the street after the floods) does not have a website'. Wrong, I checked and found one in the local language, Georgian.

Please do not assume that when you do not find something in English, it does not exist. 58.174.193.115 (talk) 05:08, 16 July 2015 (UTC)

Found a reference to a petrified-lime bridge in France from the 1867 Commercial Handbook of France.[4] "A spring, highly charged with carbonate of lime, issues from the side of a hill, and deposits along its course a constantly increasing mass of white travertin. ... terminating in a rude but picturesque arch of the same material." There was a mini-industry at the time of placing objects to be "petrified" where the stream's water would run over them, depositing limestone over the surface. This is the extreme case of the process by which pipes in hard water areas clog. It has little to do with hemp. John Nagle (talk) 06:15, 16 July 2015 (UTC)

Contested content

This evening I removed two lines of text that appeared to be editorial comments typed right into the main page. The first one referred to the strength of hempcrete and I believe that issue was resolved above. The second one however sounds like a legitimate question about the reliability of one of our sources, and present the comment along with the contested content (both of which I removed from the article proper):

Tests in Sweden showed disappointing thermal performance: "The hempcrete building system showed to have a thermal performance similar to that of passive houses in more southern climates. In the north of Sweden however the hempcrete building required up to 20% more energy than the passive house to maintain comfortable indoor temperatures." - This is speculative and based on a software simulation that a student performed for his university project that takes into account only the U values, not the thermal mass of hempcrete.

Can we discuss whether any part of this belongs back in the article?

Thanks, Dusty|💬|You can help! 00:52, 26 January 2015 (UTC)

References

"virtually waste-less"?

What does that mean??? Doesn't that basically mean "no waste"? SnappingTurtle (talk) 03:21, 20 October 2015 (UTC)

Took out the ad-like material for "hempstone", which is a proposal for funding, not a product.[5]. WP:CRYSTAL applies. John Nagle (talk) 06:34, 20 October 2015 (UTC)

Insulation

As a novice to hempcrete i'm making the following observations:

The mentioned R value per cm or inch (0.67/cm to 1.2/cm) seems really high to me (as a building professional) and is also in contradiction with the mentioned thermalconductivity. A thermal conductivity of 0.05 W/mK to 0.138 W/mK converts to a R value of between 0.2/cm and 0.07/cm.

I don't have access to 'Stanwix, William (2014). The Hempcrete Book: Designing and Building with Hemp-Lime. Green Books'. The other links are dead and I can't find them anywhere else either. ('Magwood, Chris (January 7, 2016). "Building with Hempcrete or Hemp-Lime http://endeavourcentre.org/2014/11/building-with-hempcrete-or-hemp-lime/' and 'Kenter, Peter (2015). "Championing Hemp: Ontario Builder Promoting Use of Hempcrete". http://endeavourcentre.org/2014/11/building-with-hempcrete-or-hemp-lime/') Aldo.15 (talk) 08:20, 11 July 2023 (UTC)

Please rewrite this

In addition, hempcrete's mechanical properties, when used in prefabricated blocks specifically, act as a carbon sink throughout its lifetime.

Mechanical properties cannot act as a carbon sink. Nankai (talk) 00:14, 5 October 2023 (UTC)