Tricalcium aluminate (C 3A) is one of the four main compounds found in Portland cement, along with tricalcium silicate (C 3S), dicalcium silicate (C 2S), and tetracalcium aluminoferrite (C 4AF). C 3A is particularly significant for its role in the early stages of cement hydration and setting. It reacts rapidly with water and gypsum (added to cement to control set time) to form ettringite, which initially contributes to the early strength and heat release during cement hydration. The presence and quantity of C 3A in cement are critical factors in determining the cement’s reactivity and suitability for different environmental conditions, especially where chemical aggressiveness, such as sulfate exposure, is a concern.