First I have a question :?: :?: :?: does your beardie have a hide? If he doesn't have someplace dark to hide in that may be why he is burrowing. If he has a hide and is still at it then maybe he is trying to dig.
I personally have seen the difference sand can make to a dragon who likes to dig. When I adopted my dragon he was on reptile carpet. He was depressed and grumpy. I noticed him trying to dig in his cage quite often and after reading the care sheets here decided I would change him to play sand. He was so happy to have somewhere to dig! The change in his personality was amazing! He was alert and active, which was something I had not seen since I brought him home. And friendly! And he actually seemed to genuinely like it. For the first time since I brought him home he actually seemed happy!
I'm going to slate tile as soon as I find some I like around here but I plan to make a little sandbox for Bob. I couldn't take it all away from him! Not after seeing the change sand made to his personality. I'm actually kinda worried changing him to tile will be really upsetting to him, but I am far more concerned about him eating too much sand and getting impacted not to. I know leaving some sand in there I still have that chance, but that chance is greatly reduced. I know there are several opinions on this but I'm all for a sandbox. I think it's good for Bob's state of being. And if they like to dig it's great exercise!
You'll always get people telling you no sand, it's bad, it's evil, sand = devil :evil: , it can lead to impaction which can kill your dragon. Which I agree is an issue, but a few simple steps and the risk is greatly reduced (
bathing regularly and not using calci sand namely). Sand seems to be a heated debate here. In the end I think you should go with what you feel.... and if you feel your dragon needs a sandbox I'd give him one. Now if you see him eating sand after the initial tasting process then I would consider taking it out. And I wouldn't suggest using calci sand because it clumps like cat litter. Play sand is fantastic! And cheap!
In the end no, dragons don't NEED sand. But it if makes them happy, how can you deny that? It's like a kid with a skateboard. Yes there are risks, but if do your best to eliminate the risks as much as possible and are a responsible parent then how can you deny something they enjoy? That's my honest opinion