"Am I crazy?" Um ... let's see. Why don't you describe "the look" of a recycled concrete retaining wall and we'll see if you really know what you don't like the look of. I'm thinking that you're envisioning a wrong-way use of the material because, as a rule, it's a great looking material. The problem is usually getting enough of it, right size pieces and handling them. Do you NEED a retaining wall or are you just trying to find a way to use a material that you already have? How high the wall? The schemes you describe of using the concrete sounds inferior to using it another way. The quality of the concrete is good? (meaning that it's not a thin plaster of concrete done by a penny pinching homeowner and is broken up already to smithereens... crumbles?)

Yeah, I don't love the look either.
I've seen only one recycled concrete wall that looked decent ( by Shirley Watts ,East Bay designer ) and they took pains to cut the concrete edges smoothly and lay it up nicely.

There is no reason to use the recycled concrete to add stability to a new poured in place retaining wall. The new wall has to stand on its own structurally .

if you don't want to pay for a rock box dumpster you can stack the concrete and face it with corrugated metal + 4x4's . We've done this in Mill Valley ( just down the road from Novato) and it's a somewhat sustainable way of reusing the the concrete chunks on site - but it is a fair amount of labor vs. a rock debris box that is just a couple hundred bucks.

For all practical purposes, broken concrete is little different than just another type of stone. As with every material, it makes a difference how one uses it. Here's a couple of examples, that while not ideal, are pretty decent. Putting more batter on the wall would help its stability and appearance.

you can call it "urbanite" like the cool kids do but it's still just busted-up patio pieces.

The poured concrete thing is fraught with problems if you skimp on footer and pour thickness, and is needlessly spendy if you don't (unless you like the look and you dumpster the concrete debris).

The metal thing? Sure, it's a neat look, but how much planting space are you losing by doing the panels, a gap for aggregate, and then the wall?

If faced with doing a recycled concrete wall again I would take the tack of dressing the face. I think it gives the product a more elegant finished look.
{{gwi:25846}}From AIA garden tour 2009
{{gwi:25848}}From AIA garden tour 2009

Above work by Shirley Watts

It might even work well to combine a nice saw cut face with a corrugated walls or a core ten steel wall. Marcinde has a point that there is some space lost when using the "urbanite" as the structural lay-up of the wall behind the metal. But It might be something worth considering if that is a look that appeals to you.

I would definitely check out core ten too. Van Bebber up in Petaluma can give you some prices.

How much concrete are you trying to get rid of, and how thick is it? What is the quality of the old patio's concrete, and how do you intend to break it up? How high will the visible portion of the retaining wall need to be?

I physically and mentally can relate to the pain. My husband and I are in the process of removing more than 1500sq' of 4-5" thick concrete of varying quality. Roughly 85-90% of which has to be reworked into the landscape design. Cascading plants are going to have to do their work to soften the raised beds.

If your patio is not large, you may want to seriously consider just having it hauled away...

Concrete slab can also be saw cut as in the Shirley Watts garden, but laid vertically, if you were to cut the slab into 3 foot wide by 6 to 8 foot long pieces and sunk 1/3 into the ground, it could also give a cleaner look.

Looks like ahirasaki may have abandoned the thread since no feedback on anyone's comments.

To be sure, installing sizable slabs vertically will add significantly to the cost as this isn't something one or two people would be physically able to do. It would require some type of mechanized lifting equipment and access to the site for the machinery. It would also require some precision work in order to obtain uniform level at the top of the slabs. Seems like it would be a difficult method for typical DIY.

"... a cleaner look..." comes down to whether a person wants reused concrete to continue to look like concrete ... or if they want it to look like stone. Retaining walls of recycled concrete are used extensively on the U of Illinois campus. Almost everyone thinks it's stone because that's what it looks like after it ages out a little. They're handsome walls because of their design and workmanship.

Concrete ... or stone ...?
{{gwi:25849}}