Andesite and rhyolite are volcanic rocks used as aggregates in concrete production. Andesite, characterized by its intermediate silica content, offers moderate strength and good durability. Rhyolite, being more siliceous, typically displays higher strength and excellent durability, but it also has a higher potential for alkali–silica reaction (ASR), a common problem in concretes exposed to severe environmental conditions. The choice of these aggregates in concrete mix design is often influenced by their local availability and their physical and chemical properties, which can significantly affect the overall performance of concrete structures.