Can this tiles be installed directly on the sand? Will the sand slip through the holes when weight is applied?

We recommend installing our Rugged Grip-Loc Tiles over a hard, flat surface such as concrete, asphalt, or wood decking. If you place these over sand, they may not stay interlocked very well, and the sand would come through the vents in the tiles. Customers have installed these tiles over sand with success. So if you are ok with these inherent issues, these tiles will work perfectly for you.