I think there could be something to it, but I was never a fan of "mechanic in a bottle" types of solutions. I understand that there could be situations, of a less serious nature, that might benefit from such a practice, but I've never been fortunate enough to have seen it work.
Limestone dust is just that..dust. I would put it somewhere between sugar, and flour as far as granular consistency. While it is certainly not concrete, when it gets wet it basically sets up....no real structural strength, but I've still needed a hammer and chisel to knock it loose on occasion.
