Comment by erikpukinskis | Hacker News Reader

Comment by erikpukinskis | Hacker News Reader

Cement is cool. But you know what’s really cool?

Rammed earth.

It won’t crack like cement. It doesn’t require any special chemicals like cement. Doesn’t need to be shipped anywhere...

At least not... as much of it. If you built a rammed earth structure you will use a little cement actually. So everything that’s in cement, there will be a little of it in your rammed earth home.

But mostly you’ll just use readily available local-ish materials. Now for the benefits:

- Will last 1000 years

- Perfectly finished on the inside and outside with no fussy carpentry, mudding, or painting

- Thermal mass for free

- Load bearing

- Sheds water

- Breathable

- Insects won’t bother

- Basically as strong as stone

- Stunningly beautiful

- Largely free of odd vapors and perfumes

I am a fan.

There are downsides. It’s not right for every application. It is labor intensive. And it’s skilled labor bordering on artistry. But from my research, it’s the ultimate wall there is.

You aren't exactly correct. Cement is a binder. Cement can be used to bind rammed earth. I think you mean to say "Concrete." There is a difference.

Rammed earth will crack in a flat application just like concrete, which also will not crack as bad in a wall formation as it will in a flat foundation type application. This is due to rammed earth and concrete having excellent resistance to compression, as gravity does to a wall, but they are both weak in tension.

Sometimes rammed earth does require binders like I said before depending on locally available materials. There is fussy carpentry involved because you need to make forms for the walls within which you ram the earth.

It's not as strong as stone, unless you use the appropriate binders and you should get your finished product tested for strength before using it in a load bearing capacity.

It's still a good building material, I do agree with that, but it is not just as good as concrete and it only approaches the strength of concrete when cement is used as a binder. No readily available natural materials come close to the strength of cement bound aggregates.

Not totally weather resistant. And you likely need to stand it up on stone, or waterproof foundation. Walls need good capping. Good eaves help, but once you are at this kind of structure, tmberframe or concrete column, with any old in fill may do. Many modern concretes are blends, papercrete, hempcrete, timbercrete, benefit from breathability. Rammed earth at least benefits from reusable form work. And I reckon could easily be automated. Clay and straw is a classic too. A mix of materials a good idea, especially given building sand scarcity and environmental destruction.

I agree with most of that.

Primarily, I agree that concrete is easier if you are looking for a “no brainer”, just pay someone and forget about it type project.

But if you are willing to do some more leg work to find good people and can afford to pay them, rammed earth will be a better result for most small (<10,000 sqft) “sub-urban” applications.

I am in the planning stages of building a 25 foot obelisk on my property. I was planning to use concrete and hadn't heard of rammed earth. Is rammed earth an appropriate material for my project?

(Everything thinks I am joking about this but I am 100% serious)

Does it have some sort of purpose? Personally I would choose granite since I don't want people to think my god is poor.

GP could use Wallington's technique and place a monolith: https://en.wikipedia.org/wiki/Wally_Wallington

No, just something aesthetically appealing and it would remind me of my favorite computer game as a kid, Heroes of Might & Magic 3

Where are you located? I hope to put a variety of sculptures (and maybe an obelisk or two) on my 5 acres in South Florida

New Jersey

No, rammed earth needs a roof above.

Ok, thanks

I am not an expert, but why then most of the world has switched to cement, when cement is available at the right price?

According to the wiki[1]:

> Interest in rammed earth declined after World War II when the cost of modern construction materials decreased.[citation needed] Rammed earth was considered substandard, and still is opposed by many contractors, engineers, and tradesmen who are unfamiliar with earthen construction techniques.[7] The prevailing perception that such materials and techniques perform poorly in regions prone to earthquakes has prevented their use in much of the world.[citation needed] In Chile, for example, rammed earth edifices normally cannot be conventionally insured against damage or even be approved by the government.[citation needed]

Lots of missing citations, but seems reasonable. I for one had never heard of this construction technique until today.

[1] https://en.wikipedia.org/wiki/Rammed_earth

David Suzuki profiled a rammed earth house on Vancouver Island that's a neat overview of it in action: https://www.youtube.com/watch?v=ra4Pldetd_M

I am native german, surely did a lookup what rammed earth is, but didn't come to a conclusive result. Is rammed earth the same as clay plaster?

This is the high end: https://youtu.be/hLu2gxsVBe0

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