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Earthbag Building & Other Natural Building Methods

Bullet Resistance of Compressed Earth

Earthco Building Systems, Inc. performed some interesting bullet resistance tests on their compressed earth Megablocks. Their website says they used 50 caliber BMG armor piercing military ammunition. Densely compacted earthbag walls made with subsoil would likely have comparable results. Maybe someone with a rifle and spare time could conduct a similar test on earthbags. Please email me and I will provide a few suggestions.

Test results using 50 caliber bullets on an unprotected 8 month old wall that received 10” of rain:
- 5-1/2” – 7” penetration
- 10” penetration with two 50 caliber rounds fired into the same hole
- 5 shots in 6” circle without full penetration on 18” thick walls
- little to no cracking

More videos and information at Earthco Building Systems, Inc. website.

Bullet Resistance of Sandbags

Update and clarification from Larry Williamson of Earthco Megablock:

Gentlemen please let me clarify — Owen you made a slight miss- association error — On our website we state we have tested our Megablocks against armor piercing rounds but in this video we are not using “US military issue armor piercing ammo”. An easy assumption to make.

In this particular video we used 50 cal “BMG” 661 grain Full Metal Jacket over a stainless steel core — muzzle velocity of 3100 fps and delivering 12,400 foot pounds of energy. Let’s not get off track here. The important thing is that an 18″ thick natural earth wall (just soil and water — no cement or lime stabilizer) absorbed over 86,000 foot pounds of energy and remained structurally intact.

I would expect earthbag walls to perform with similar results — perhaps a little more penetration due to less density— but vastly superior to timber frame, CMU or ICF construction and the same ammo.

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8 Responses to “Bullet Resistance of Compressed Earth”

  1. Eagleclaw1 says:

    This is some valuable information. I thank you and yours for your time researching/testing and posting it.

    I am still looking around your site. But I do have a few thoughts.

    After watching the video tests and reading the article. I think the compressed earth blocks could be made even stronger. Besides easily adding cement or lime stabilizer .

    Never to withstand a missle or bomb strike/impact…. But the blocks could possibly take more [hammering] from .50 cal rounds and smaller arms fire without fracturing or blowing out as easily.

    I have seen some earth blocks made like these in the Sahara Dessert [Algeria Oil fields]. They were made for the same purposes and reasons. Some are ancient dwellings and time/wind has exposed some strengths/weaknesses.

    If people have the foresight or reason— or are preparing these types of dwellings.

    If you used a medium/smaller mesh chicken wire panel or panels in the middle or the length of each brick when being made.

    When the block is solid/hard and then turned face out. The mesh [might] would help stop fracturing and blowouts.

    If the mesh was to small— the impact/hammering might cause the bricks to fail/split?

    But— in watching the test with the .50 and .223 fire tests.

    I think— if the [cheap] mesh/chicken wire was done right you could increase the over all strength/stamina of the block.

    Especially around gun ports/air vents/doors/etc. If it is a closed type shelter/fortress.

    Just a few thoughts.

    Either way Keep up the good work patriots!

    mike/III
    Texas/Coastal

    • Owen Geiger says:

      Yeah, I am sure there are lots of ways to improve on the basic system. But it’s good to know that tamped/compressed earth is quite bullet resistant even without lots of added reinforcement, time and money.

      There are other blog posts that discuss ways of stabilizing the soil with lime, cement, gypsum and using naturally occurring caliche soil. This isn’t typically necessary, but is an option for added strength and water resistance.

  2. Gentlemen please let me clarify — Owen you made a slight miss- association error — On our website we state we have tested our Megablocks against armor piercing rounds but in this video we are not using “US military issue armor piercing ammo”. An easy assumption to make.

    In this particular video we used 50 cal “BMG” 661 grain Full Metal Jacket over a stainless steel core — muzzle velocity of 3100 fps and delivering 12,400 foot pounds of energy. Let’s not get off track here. The important thing is that an 18″ thick natural earth wall (just soil and water — no cement or lime stabilizer) absorbed over 86,000 foot pounds of energy and remained structurally intact.

    I would expect earthbag walls to perform with similar results — perhaps a little more penetration due to less density— but vastly superior to timber frame, CMU or ICF construction and the same ammo.

  3. [...] Bullet Resistance of Compressed Earth Earthco Building Systems, Inc. performed some interesting bullet resistance tests on their compressed earth Megablocks. [...] [...]

  4. Will Brown says:

    A Full Metal Jacket round doesn’t share the same terminal ballistics characteristics as an Armour Piercing round does (the brass jacket serves to keep the bullet’s lead core from fouling the barrel’s grooved rifling; FMJ and AP bullets are constructed quite differently), you really ought to correct your post’s attribution. The Earthco video correctly identifies the round fired as FMJ. Mis-attributing the construction material’s performance really does the product a (I’m sure unintended) dis-service as it’s recorded performance is quite impressive all on it’s own.

  5. [...] Earthco Building Systems, Inc. performed some interesting bullet resistance tests on their compressed earth Megablocks. Their website says they used 50 caliber BMG armor piercing military ammunition. Densely compacted earthbag walls made with subsoil would likely have comparable results. Maybe someone with a rifle and spare time could conduct a similar test on earthbags. Please email me and I will provide a few suggestions. Test results using 50 … Read More [...]

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