Posted on 12/01/2023 1:18:27 PM PST by Red Badger
It sounds like a headline from the future: the weekend before Thanksgiving, a bulldozer came for the first example of a printed home that was supposed to help the housing crisis in the city of Muscatine. Fortunately, it hadn’t been completed and sold yet.
Printing of this first house began in May 2023, and nine more were to be completed by the end of the year. The house was being constructed from Hempcrete, which a biocomposite of hemp hurds, and either lime, sand, or pozzolans that is used in Europe and Canada.
In tests, the hempcrete was capable of reaching a compressive strength of 6,000 to 8,000 PSI. But in actuality, it didn’t even meet the 5,000 PSI minimum required for the project.
The project is a collaborative effort between the Community Federation of Greater Muscatine (CFGM), Muscatine Community College, and Alquist 3D. Although not as proven a printing material as traditional concrete, Hempcrete was chosen in part because Muscatine Community College has Iowa’s only hemp program. One of the goals for the project was to have students research hemp’s properties, and launch a 3D printed construction curriculum in partnership with Alquist 3D.
The project’s leaders haven’t given up hope yet. Although it was back to the drawing board to get the hempcrete just right, it should now meet the 5,000 PSI requirement. The plan is to start building the originally-planned second house in the spring, and begin construction on this first site after that.
Want to know more about the state of 3D printing when it comes to housing? Check out our handy guide.
VIDEOS AT LINK.....................
Hard to believe they actually went to production BEFORE lab testing the material. And this is being run by a college?
According to the article, they did test it. It performed differently in real life from testing.
In tests, the hempcrete was capable of reaching a compressive strength of 6,000 to 8,000 PSI. But in actuality, it didn’t even meet the 5,000 PSI minimum required for the project.
Something wrong with their test protocol? Something wrong with how they deployed the stuff on site?
Have they thought of constructing the with adobe?
They did. According to the article, it tested between 6,000 and 8,000 psi. But when they tried to use it for an actual structure, its compressive strength was below the 5,000 psi it needed to be.
This is how science works; experiments can go wrong many times before the researchers figure out why. If it were easy, we'd have figured everything out millennia ago.
“It seems as though the alkali in concrete could negatively affect hemp cellulose; it wouldn’t be my choice of reinforcement.”
and there’s this:
after it was discovered, sisal fiber replaced the use of hemp fiber for marine ropes and hawsers because hemp fibers are hollow and tend to absorb water when wetted ... to keep hemp ropes from rotting, they were heavily coated with tar, which of course got all over everything, especially the sailors, thus the slang term “tars” for sailors ... and all because hemp fiber rots when wet ...
> One of the goals for the project was to have students research hemp’s properties,
And while the students never produced a finished paper, they did run up an astronomical bill at the local Domino’s Pizza.
“Something wrong with their test protocol? “
probably didn’t do testing after the hempcrete aged a while and the hemp fibers rotted from the moisture in the mix ...
I wonder if 3d printing a foam encased cavity and then pouring concrete would be a better option.
You know a lot of times at work they want you to use the same material for different applications.
This just happened to me. I told them we could not radiation sterilize our product but they insisted. Of course after thousands of dollars spent the experiment was a bust.
The material is of the same class as hemp cellulose but comes from a marine source. After reading the article it seemed this must be the problem: so they had a hemp farm and hemp had to work because that’s what they wanted. You can’t substitute one material for another just because you grab whatever you have.
I liken it to watching a carpenter using a hammer and asking him to precision cut boards. But you don’t want to pay for a saw so you tell him to use his hammer.
It doesn’t work that way.
The technique of printing structural materials is okay when cost effective. Use concrete, it works. Organics should be left out of the mix unless it is Adobe Brick which is not suitable for 3D printing. Adobe is great in the Southwest and a cheap material. It is not suitable for a wet climate.
snow loads I can understand the concern, but building one stories down south shouldnt be an issue...
Building a better mud hut with pot - maybe.
Brought to you by White Rabbit Timothy Leary Construction, more or less.
Hemp, another solution to every problem known to man except it’s desperately looking for a single problem it can solve well.
The only reason we have this raw material is dope growing operations.
Hemp used to be grown commercially, mainly to make rope and canvas. But the material has been superseded with other better materials.
A fraternity buddy in Missouri had lots of old hemp fields on the family farm. It had been grown commercially decades earlier to produce rope. Helpful hint: don’t try smoking the stuff.
The mechanical properties of hemp have been studied for decades. It’s well-known to have very poor compressive strength and it needs the support of some structure around it. Apparently it does have good thermal and acoustic insulating properties, but you have to build it into a surrounding structural wall.
Sounds like the “tests” weren’t very real-world.
Check out what is used for aggregate in the lightweight concrete used in floors in multi-floor buildings.
Then you’ll know why so much dust was generated when the Twin Towers collapsed.
The Pantheon in Rome has only stood for 2000 years, probably going to dissolve any day now...
1400 sf for $300,000? You gotta be kidding me. I’ll bring in a 1,000 sf addition with bathroom and septic for less than $90 a square.
Would aircrete work?
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