Alkalinity refers to the capacity of an aqueous solution to neutralize acids, a critical factor in the chemistry of cement and concrete. In concrete, the alkalinity is primarily derived from the presence of calcium hydroxide, a byproduct of the hydration of Portland cement, and is crucial for maintaining a high pH environment. This high pH environment is essential for the protection of steel reinforcement from corrosion. Moreover, alkalinity in concrete influences various durability aspects, particularly its resistance to acid attack and the mitigation of potential deleterious reactions such as alkali–silica reaction (ASR), which can lead to structural damage under specific conditions.