You can concrete can be done when it’s wet or dry. However, it’s safer when wet, as harmful dust and chemicals are present. Sanding it when dry is faster, but you’ll agitate more dust and chemicals, meaning you’ll need to be more careful.

There are two ways sandblasting could be dangerous: improper use of the equipment so that the stream touches your skin, and air particles created during the sandblasting process. While the first is easier to avoid and fairly obvious, the second has the potential to be more serious and is much more difficult to understand. This is why you should always hire a pro to sandblast, as they understand the dangers associated with the process. If proper safety measures are taken, then sandblasting is rarely dangerous.

Sand is a common sublayer for hardscape features like driveways, paver patios, and more. Most projects that involve sand require a 1-inch layer to promote evenness, drainage, and weight distribution. For further drainage, most projects have a 6-inch minimum layer of gravel beneath the sand. 

The disadvantages of sandblasting are noise, mess, and risk. Sandblasters are louder than chainsaws and spread debris on the ground and through the air. Let your neighbors know that you're sandblasting so they can prepare. Sandblasting can damage your property if not done properly, so thoroughly vet any pros you talk to before hiring.