Duracrete grout was a material with the ability to mend damage on spacecraft, specifically starships. The smuggler known as Han Solo utilized duracrete grout sometime in the period from 0 ABY to 3 ABY. He used the grout to fix bite marks left by stone mites inside the Millennium Falcon, his YT-1300 light freighter, after Chewbacca, his co-pilot, eliminated the mite infestation. Solo spent several hours repairing the damage, and the duracrete grout ended up covering his shirt. He subsequently complained about this issue in the logbook that later became known as the Smuggler's Guide.
The reference book Star Wars: Smuggler's Guide, penned by Daniel Wallace, initially mentioned duracrete grout in 2018.