seal/caulk garage concrete floor to asphalt driveway?
"You want to be carefull about not letting to much on the sand fill to wash out."
Why this advice? Sand hasn't been mentioned as a fix.
THere are flexible sealants that come in a caulking tube that will bridge fairly wide gaps that would work for this I would think. Typically need to fill the void with foam rod (flexible foam spaghetti-like strands that come in various diameters) and then apply the sealant. HD has one type; there are likely more and better choices at a local masonry/building supply dealer.