I am building a large patio, the site is sloped. The soil is clay heavy. I'm in Colorado Springs for those that know our conditions.. also freeze thaw cycles.
I need a retaining wall about where it's highest point will be about 40" tall to hold back the fill to make the site level. Code says I can build 48" without approval/dwgs/stamps. Talking with code enforcement in person - they don't really care what we do, as anything we do to our yards under that is considered landscaping & as long as we don't change drainage easements they don't care about much. Most of the sections will be <30" tall.
So. I'm thinking tires. I will dig a shallow trench foundation (18"), fill with recycled crushed concrete & lay my 1st course 1/2 in the ground (about 5"). I will scrape the top soil of organics & compact a layer of the crushed concrete into the (moistened) ground to stabilize that earth. I will backfill/level the patio area with more crushed concrete... estimated to be 90 tons worth. This will be deep... 8" to about 38" deep... creating a giant drywell for rain & snow melt. On top of that will be standard patio sand & pavers.
Primarily -
1 - Can I use gravel/crusher run/crushed concrete to fill the tires instead of dirt/soil? I am concerned about a)having enough "dirt", b) swelling/shrinking due to high clay content, c) water drainage d)frost heave.
Secondarily -
2 - I have access to several hundred tires - should I use extras to further stabilize the back fill... like a giant geo grid... copying what is being done on some civil engineering projects where they call it "mechanical concrete"?
3 - Should I fill any of the tires in the wall with concrete? Perhaps the top course (I read Reynolds's books a long time ago - I believe that's how the bond beam is done on earth ships???).
4 - Would configuring the tire wall to match the angle of reprose for the crushed concrete be overkill/over thinking... or should I consider that when laying the tires for set back?
Thank you for your time & consideration in this.
