11-11-2013, 02:08 AM
I have pondered this at great length. What are you hoping to accomplish by using the rock, and I'm not being snide, just practical. Both for practical earthquake protection and to meet code you would need reinforced concrete. In fact, adding rocks would increase the amount of concrete and rebar needed not lessen it so from a pure sustainability standpoint you would lose rather than gain by using rocks. Stone walls don't have this problem, being dry stacked, but that is because the risk of being crushed beneath a 6' garden wall on the property line is so small compared to the risk from a 10' house wall that is also holding up the roof over your head while you sleep.