A new analysis reveals how damage progresses in concrete that's exposed to sulfate, a nearly ubiquitous compound. The work could lead to the design of concrete structures with improved durability, the report's author says.
Concrete is made with Portland cement, a powdery mixture of crushed limestone and clay or shale. When the cement is mixed with water and added to gravel and sand, the resulting slurry hardens into concrete.
Portland cement consists primarily of four minerals: tricalcium silicate, dicalcium silicate, tricalcium aluminate, and tetracalcium aluminoferrite. The chemical reactions among these compounds and water form a glue that binds the gravel and sand.