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.
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.