The carbonation test, using phenolphthalein indicator, assesses the depth of carbonation in concrete. A solution is sprayed on a freshly exposed concrete surface; it turns pink in alkaline (non-carbonated) areas and remains colorless in carbonated zones. Carbonation reduces concrete’s alkalinity, increasing the risk of reinforcement corrosion. This test helps determine the extent of carbonation, guiding repair strategies to protect and extend the structure’s lifespan. It’s a simple, effective way to evaluate concrete durability and plan necessary interventions.