I think your best method of amending and aerating is to add lots of compost to the native soil and then let your earthworm population do your aerating for you. Expanded shale might help to loosen the clay, but I don't think it will have much value beyond perhaps some trace elements and moisture retention (which your clay already has). As time goes by you may need to add more compost in the form of mulched tree leaves, grass clippings etc, but you will also get organic matter from your plants as they go through their life cycles. I can't imagine how a liquid aerator can work - I think it's probably hocus pocus stuff. Nothing works better than compost!

The problem with adding organic matter to improve soils is that you need to keep doing it. For the most part it degrades into water, carbon dioxide, and a relatively meaningless amount of minerals.

Expanded shale is a much more permanent fix, but you will need to till it into the top several inches of soil which means tearing up whatever is there now.

I know nothing about liquid aerators and seriously doubt they are efficacious. You could have you landscape core aerated and topdress with organic matter and coarse sand. That would be a major improvement.

We did use the liquid soil aerator, and it worked great for us.
The back of my yard was too shady for grass, so I bought some bulbs to plant last winter. You couldn't get an inch down in the soil. My husband tried a power drill with a wide drill bit, but even that wouldn't go into the soil.
I ordered the aerator on line, not expecting much. I am happy to say, we are now planting bushes and shrubs in the back with no problem. Also, we have used this in our entire yard, and our grass was beautiful last year.
Now, we did use it more than once. I think all together 4 times in the trouble spots, but after the first application, you could tell a very noticeable difference.

The expanded shale is okay, but after talking to someone who is a landscape supervisor, he has come to the conclusion that the clay will win over the expanded shale. He believes that eventually, the pourous texture of the expanded shale will fill up with the particles of clay and not be as much benefit as plain old compost. Yes, you do have to reapply compost occasionally, but it is what Mother Nature is already doing in our forests to feed all the plants and trees that grow wild. I am not familiar with the liquid aerator at all. I didn't even know anything like that existed. I'll keep adding compost to my garden since that is what keeps the soil the most friable.

msggie1, which product did you order? i saw a couple online. I spray the lawn and beds with with a seaweed mix and I'm trying to figure out if these products are similar. Thanks!

I believe it was called Aerify. The product we bought was used with a conditioner of some sort. We bought both and used as directed. It kind of foams when applied, then you have to water.

Aerify foams because it contains the same ingredient used in soap. ammonium laureth sulfate. (Label: http://www.natureslawn.com/aerify_label.pdf) I just ordered Lazyman Liquid Gold (Description: http://www.outsidepride.com/catalog/LazyMan-Liquid-Gold-p-18066.html)
Hopefully this will help out my concrete-like backyard. Plus I am considering buying several pounds of earthworms and putting them down to keep the lawn softer.
I'm planting Tall Fescue, which hasn't done so well up to this point, and a little white clover - which sprouted after three days.

Very useful for me as a mulch for my herb garden, patio potted plants. It has given me amazing results holding in moisture for areas and pots I have to water daily or twice daily. Now water every few days and use less water. Central Texas drought and 100 degree temps in May. Expanded shale to the rescue for me.

In 1950 my mother agonized over the front street corner of our lawn where the electric company had placed a pole and left a big circle of red clay.

I remember that she ordered something liquid that worked like magic. I have often wondered what it was.

I drove by that house recently and 60 years later that corner looks better than the rest of the yard.