Is that sand as a grout type of thing? i can't tell from that picture.. it looks like it though if it is i think that your SC wouldn't be a good idea, what about DS some SH on it and letting it dwell then rinse?
Ive done pavers with sand inbetween without any problems, but they were super close... if it's just a construction dust,. a little SH and some rinse action might handle it.
Anyway you do it, it will leave a bigger mess than you may start with, hitting the cracks full of sand with a wand or a SC is not good....but I am sure u know this.