According to the bags of 'lime binder' you're using, this is not a lime based binder but a very strong portland cement mortar with very little accrual 'lime' and then the lime used in the bag is not the type you need. You're adding portland cement to an already high ratio of portland and hydrated lime with very little sand. you're getting into the Type M range here. I'm sure it will produce a 'hempcrete, but this mix is not as 'green' as you think it is. Lime mortars are very complicated and still very few people understand the way it carbonates and reacts to pozzolans. Hydrated masonry lime is NOT a 'lime binder', btw.
@@AllTraderKorea The whole premise of 'green concrete' is to reduce or eliminate portland cement. The lime used in hempcrete is slaked high calcium lime either in putty or powdered form. 'Hydraulic lime' already has a natural impurity, clay, containing alumina silicate which is in the hemp fiber already, and only comes in powdered form but it works. Putty is better than powdered as it already contains the water needed for mixing while powder needs water added and tap water reduces the pH considerably, reducing performance by reducing the acid-base reaction between the lime and the hemp fiber. Powdered limes also are in bags that are rarely airtight so begin to carbonate in the bag on the pallet which reduces performance, while putty is typically in sealed containers and the putty form is far less vulnerable to air contamination. But non-hydraulic lime is the only type shipped or stored in putty form, because the hydraulic sets up even in airtight containers. No portland cement should be used in real hempcrete that is suppose to be 'green'. When used in portland based hempcrete the hemp fiber acts as a pozzolan that will react to the by-product, calcium hydroxide, of the portland hydration process making it more stable and will add fiber strength and reduce the weight by volume, but will also open the cement up to water intrusion through the fibers, but will act as an expansion buffer in extreme thermal cycles so can reduce cracking. Using something like hempcrete should be analyzed/considered carefully before large scale installation as the results can be detrimental to your project if not used carefully. When building a home, make sure you use the proper materials because fixing your mistake is expensive not 'green'. 'Lime' is both the oldest and most basic but also the most misunderstood material in all of the construction industry.
@@AllTraderKorea hello, I've been using 40% MK to 60% hydrated lime. Though it's not exact at all. We are currently doing all the hemp work and all the mixes so far have set really fast.
@@EastyUKhave you tried using less MK? Here is an interesting info. Natural hydraulic lime (NHL) is classified for different uses[2] the first two of which are sometimes called semi-hydraulic lime because they initially set with water but continue to set in contact with carbon dioxide in the air. Feebly hydraulic lime Edit Feebly hydraulic lime (NHL 2) is used for internal work and external work in sheltered areas. Feebly hydraulic lime contains up to 10% clay / clay mixed with other impurities. It might take one week or more to set after the addition of water. Setting is the process of permanently taking the shape into which lime has been moulded. Moderately hydraulic lime Edit Moderately hydraulic lime (NHL 3.5) can be used for external work in most areas. Moderately hydraulic lime contains clay in the range of 11% to 20%. This type of lime sets (assumes given shape) within a few days after the addition of water. Eminently hydraulic lime Edit Eminently hydraulic lime (NHL 5) is used for external work in exposed areas, such as chimneys and for floor slabs/underpinning. Eminently hydraulic lime contains clay in the range of 21% to 30%. Properties of eminently hydraulic lime are close to those of cement. Eminently hydraulic lime sets within one day after the addition of water. But in another place I read, " the most appropriate for use in hemp-lime material was to be chosen - a dolomitic lime DL60 with 40% metakaolin additive. The ratio of hemp/binder 0.38 gave the best results - compressive strength of 0.221 MPa at 10% deformation and thermal conductivity of 0.0757 W/m2k, which is considered a good result and shows a possibility for this material to be used as self-bearing thermal insulation building material."
@@AllTraderKorea if they are using hydraulic lime then it's going to be very different cure process as it's far more reactive. Hydrated lime just won't cure like hydraulic lime. I've not a clue what exactly the difference a dolomite labelled lime has on the process, I understand it just has magnesium added to it. Maybe worst for fire proofing? ;) I've not tested various mix ratios, I guess reducing the clay would increase insulation value. We have been pretty variable with our ratios probably from 25%-50% mk and not noticed a huge difference in how it's drying. Be interesting to trial a really low mix as mk is harder to procure than the lime.
It's really good but I've a doubt, hemp is all about "No carbon emission" that's why hemp is used instead of cement. So why do you use cement and sand?
Thank you! I really enjoyed learning about this material, and my dog loved it while she was able to use it. I donated it to my college program for educational reference, so her hemcrete haven was short llived. Sorry I didn't specify, but yes, you are correct. The ratio is by volume :)
Drum mixers can be used but the order of materials added to the drum should be water - binder (mix well) - then the Hemp. see "Building with Hemp" ISBN 9780955110917. But Pan mixers or Paddle mixers are easier as the materials can be put in together. However your enthusiasm is wonderful and I hope you get to progress your interest.
It's a building with no seams and if you do very little research on hemp buildings you could have your answers instead of being so quick to judge!! IT'S FAR FROM WORTHLESS STEPHEN!!!
Properly mixed and used hempcrete is perfect as a breathable insulation, especially for old buildings and can be used within well built wood framing to sustain a reasonable amount of weight. It's not made for making load bearing walls. This video is not a very good example, but you should do your research before calling this material worthless :)
Thanks Leigh from the UK . That was excellent . I'm about to build a hemp crete house and that was really useful. You should do more x
nice simple video!
looks like a kiln!
Great Job!
I'm inspired!
This looks like a fun and well-completed project. Have you been able to do anything since?
You did an amazing job documenting this! Thank you, and how does the dog like it??
you're awesome!
According to the bags of 'lime binder' you're using, this is not a lime based binder but a very strong portland cement mortar with very little accrual 'lime' and then the lime used in the bag is not the type you need. You're adding portland cement to an already high ratio of portland and hydrated lime with very little sand. you're getting into the Type M range here. I'm sure it will produce a 'hempcrete, but this mix is not as 'green' as you think it is. Lime mortars are very complicated and still very few people understand the way it carbonates and reacts to pozzolans. Hydrated masonry lime is NOT a 'lime binder', btw.
What type of lime should be used? Can you tell a better recipe for hempcrete? I heard that hydraulic lime is the one to use.
@@AllTraderKorea The whole premise of 'green concrete' is to reduce or eliminate portland cement. The lime used in hempcrete is slaked high calcium lime either in putty or powdered form. 'Hydraulic lime' already has a natural impurity, clay, containing alumina silicate which is in the hemp fiber already, and only comes in powdered form but it works. Putty is better than powdered as it already contains the water needed for mixing while powder needs water added and tap water reduces the pH considerably, reducing performance by reducing the acid-base reaction between the lime and the hemp fiber. Powdered limes also are in bags that are rarely airtight so begin to carbonate in the bag on the pallet which reduces performance, while putty is typically in sealed containers and the putty form is far less vulnerable to air contamination. But non-hydraulic lime is the only type shipped or stored in putty form, because the hydraulic sets up even in airtight containers. No portland cement should be used in real hempcrete that is suppose to be 'green'. When used in portland based hempcrete the hemp fiber acts as a pozzolan that will react to the by-product, calcium hydroxide, of the portland hydration process making it more stable and will add fiber strength and reduce the weight by volume, but will also open the cement up to water intrusion through the fibers, but will act as an expansion buffer in extreme thermal cycles so can reduce cracking. Using something like hempcrete should be analyzed/considered carefully before large scale installation as the results can be detrimental to your project if not used carefully. When building a home, make sure you use the proper materials because fixing your mistake is expensive not 'green'. 'Lime' is both the oldest and most basic but also the most misunderstood material in all of the construction industry.
can you screw (non wood) siding onto the hemp? or will the screws strip out?
If your looking for a pozzolan for the hydrated lime use meta kaolin (not kaolin clay). You can then drop the cement.
Do you know an appropriate ratio for metakaolin in lime for hempcrete?
@@AllTraderKorea hello, I've been using 40% MK to 60% hydrated lime. Though it's not exact at all.
We are currently doing all the hemp work and all the mixes so far have set really fast.
@@EastyUKhave you tried using less MK? Here is an interesting info.
Natural hydraulic lime (NHL) is classified for different uses[2] the first two of which are sometimes called semi-hydraulic lime because they initially set with water but continue to set in contact with carbon dioxide in the air.
Feebly hydraulic lime Edit
Feebly hydraulic lime (NHL 2) is used for internal work and external work in sheltered areas.
Feebly hydraulic lime contains up to 10% clay / clay mixed with other impurities. It might take one week or more to set after the addition of water. Setting is the process of permanently taking the shape into which lime has been moulded.
Moderately hydraulic lime Edit
Moderately hydraulic lime (NHL 3.5) can be used for external work in most areas.
Moderately hydraulic lime contains clay in the range of 11% to 20%. This type of lime sets (assumes given shape) within a few days after the addition of water.
Eminently hydraulic lime Edit
Eminently hydraulic lime (NHL 5) is used for external work in exposed areas, such as chimneys and for floor slabs/underpinning.
Eminently hydraulic lime contains clay in the range of 21% to 30%. Properties of eminently hydraulic lime are close to those of cement. Eminently hydraulic lime sets within one day after the addition of water.
But in another place I read, " the most appropriate for use in
hemp-lime material was to be chosen - a dolomitic lime DL60 with 40% metakaolin additive. The ratio of hemp/binder
0.38 gave the best results - compressive strength of 0.221 MPa at 10% deformation and thermal conductivity of
0.0757 W/m2k, which is considered a good result and shows a possibility for this material to be used as self-bearing
thermal insulation building material."
@@AllTraderKorea if they are using hydraulic lime then it's going to be very different cure process as it's far more reactive. Hydrated lime just won't cure like hydraulic lime. I've not a clue what exactly the difference a dolomite labelled lime has on the process, I understand it just has magnesium added to it. Maybe worst for fire proofing? ;)
I've not tested various mix ratios, I guess reducing the clay would increase insulation value. We have been pretty variable with our ratios probably from 25%-50% mk and not noticed a huge difference in how it's drying. Be interesting to trial a really low mix as mk is harder to procure than the lime.
@@EastyUK What ratio by volume do you use 4:1:1 or 2:3:3 - hemp hurd : hydrated lime&MK : water?
cement in a hempcrete mix?..
It's really good but I've a doubt, hemp is all about "No carbon emission" that's why hemp is used instead of cement. So why do you use cement and sand?
She used the wrong ingredients. No Cement or sand should have been used.
Ok, so the ratio is by volume not weight? Cause I did by weight and could tell I did it incorrectly. Live and learn;)
Thank you! I really enjoyed learning about this material, and my dog loved it while she was able to use it. I donated it to my college program for educational reference, so her hemcrete haven was short llived.
Sorry I didn't specify, but yes, you are correct. The ratio is by volume :)
thanks too much. please ingredients and proportion
Drum mixers can be used but the order of materials added to the drum should be water - binder (mix well) - then the Hemp.
see "Building with Hemp" ISBN 9780955110917. But Pan mixers or Paddle mixers are easier as the materials can be put in together. However your enthusiasm is wonderful and I hope you get to progress your interest.
Good to know. Thanks for the info!
sorry to say but, you're not using True Lime binder, and Cement should Never be used for hempcrete! Nice effort though.
You just cancelled your environmentally friendly building material with adding quickrete concrete, not necessary
how is it safe if you can get chemical burns?
100% safe. Hempcrete doesn't burn. No dangerous reactions. No scents.
It is the limestone that might cause skin reactions. Wear gloves.
You need a drying agent! It must achieve 0 moisture. It's impractical for commercial use.
Meta kaolin..
If it's not a load bering material , it's worthless!
Stephen Canas
Insulates. Pest, fire and mold resistant! Pretty big deals!
It's a building with no seams and if you do very little research on hemp buildings you could have your answers instead of being so quick to judge!! IT'S FAR FROM WORTHLESS STEPHEN!!!
Properly mixed and used hempcrete is perfect as a breathable insulation, especially for old buildings and can be used within well built wood framing to sustain a reasonable amount of weight. It's not made for making load bearing walls. This video is not a very good example, but you should do your research before calling this material worthless :)