Cayce Grall, project manager-forward for the U.S. Army Corps of Engineers Nashville District’s Chickamauga Lock Replacement project in Chattanooga, Tennessee, points out alkali-aggregate reaction, a chemical process that causes concrete to expand and crack, threatening the structural integrity of Chickamauga Lock and Dam during a tour for students from the Concrete Fundamentals Prospect Course offered by the Huntsville Learning Center on Dec. 3, 2024. The students, made up of concrete materials engineers, construction quality assurance specialists, geologists, and civil engineers from districts across the Corps of Engineers, visited the construction project to see firsthand how the concepts they’re studying in class are applied in real-world construction projects. (USACE Photo by Noe Gonzalez)