The recent update adds optical fibre as an ingredient in red circuits, I understand to provide a sink for excess sand.
I'm currently at the stage of the game where I'm making blue science (using red circuits) and sand is the only by-product I haven't bothered trying to recycle yet. Actually, sand is not a by-product of any science items; stone is but in very low quantities and there are some uses for that (bricks for military science + flooring; rail).
Personally I feel that the sand sink is unnecessary at this stage and the red-circuit complexity is slightly annoying, but it's not a big deal. Usage [of some stone derivative] in processing units does make sense.
Relevant mods I'm using: CI + alloy smelting + Lasing Around Agency + scrappy industry + scrappy chemistry
