Since the sleet and ice storm a few weeks back, our driveway and walks have been covered with about 1" of solidly frozen sleet. My snowblower wouldn't even make a dent, and whacking at it with my ice blade couldn't budge it. The next two weeks of snow and near-zero weather didn't help matters either.
I tried calcium chloride ice melter, which I don't like to use due to the harsh effect on concrete, but I was desperate. It dutifully melted down through the ice but still didn't weaken it enough that I could break it up with the ice blade.
Then a friend at work asked if I'd tried a pitchfork. I have one that I bought about 20 years ago to use in spreading tanbark. I was skeptical about using it for ice, but after several more days of futile chipping with the ice blade, I finally tried it.
Man does it work! Started inside the bare spot where my son's car was parked in the driveway, where the edges of the ice were a bit thinner. Sure enough, with a little effort, those pitchfork tines worked under the thick ice and broke it into pieces--most of which were big enough to easily pick them up with the fork and toss them off to the side. Had to clean up the smaller chips with a pusher shovel, but still.
I doubt it would work with a thin glaze of ice, like after a period of freezing rain. But on the thick stuff it really works, especially if the temps have gotten into the high 20s and there's been some sun.
It also helped break up the compacted snowplow remnants we'd been driving over at the very bottom of our driveway.
If you have brick sidewalks, especially clay brick pavers, you do need to wait until there have been a few warmer days. Our brick walks don't seem to transfer nearly as much warmth from the ground, even where exposed to sunlight. The thick ice was much easier to fork off the concrete after a warmer day than from the brick. It's gotten to mid 30s the last couple days here, and broke 40 today. Just today after getting home from work, I was finally able to break the ice off the brick walks with the pitchfork.