It's do-able, but probably pretty hard to make it look decent. I have a bunch of broken concrete and will try to put something together and see how it turns out. It can't look any worse than the pile it's in now. This may turn out to be fun!

Just a word of encouragement... a few years ago I attended a talk by Baldassare Mineo, who was then the owner of Siskiyou Rare Plant Nursery. He constructed a garden of broken cement at the nursery to show off the plants while avoiding the high cost of stone. He showed slides, and the garden looked lovely.

I second janet_e's comments. I probably saw the same slides.

I used broken cement chunks to edge my flowerbeds and also in two layers to make a psuedo rock garden across the front of my yard along the curb. 12 years later with many succulents and other plants fully grown, it looks fine to me. I could not afford all the rock it would have taken.

It might be interesting to use some concrete stain from Home depot/ Lowes to alter the color and make it blend with the surroundings more.

thanks for the encouragement... The snow is finnally gone and we are going to start our cement rock garden. We will keep you posted.