Alkali metals, primarily sodium and potassium, are significant components in cement chemistry, influencing the hydration process and the physical properties of concrete. In the context of cement, these alkali metals can either be naturally present in the raw materials or introduced through admixtures and alkali–silica reaction (ASR) mitigators. The role of alkali metals is crucial, especially under severe environmental conditions, as they affect the durability and long-term performance of concrete. Their presence can lead to both beneficial effects, such as enhanced workability and acceleration of early strength gains, and detrimental impacts, such as potential for alkali–aggregate reactions.