A couple of days ago, I needed a length of track to photograph my model of the RH&DR armoured train on.
"Ballast" was to be Chinchilla sand. When I've tried this in the past without glue, it exits the spaces between the sleepers rapidly. This time I used a method I emplyed many, many years ago for ballasting - double sided tape under the sleepers.
This helpd the track in place on the background plastic sheet AND kept sand where I wanted it.
Sand on the sleepers is perfectly prototypical and I quite like the effect. Best of all, the clean-up was quick with all the sand back in the carton 5 minutes after the photos were taken.
On a very early layout, I used carpet tape under the track and ballasted with cork granuals. OK, it was far too coarse, but the edges were lovely and neat. Recovering the track was a breeze too as it just peeled away, leaving the corky ballast behind.