Calcium deficient hydroxyapatite (CDHA) is a variant of hydroxyapatite with a lower calcium to phosphate ratio compared to the stoichiometric hydroxyapatite, commonly found in the bone and tooth enamel. In the realm of cement and concrete, CDHA is utilized for its bioactivity and compatibility, particularly in biomedical applications such as bone cements and implants. The adaptability of CDHA to harsh environments, such as biological fluids with varying pH and ionic strengths, offers insights into its potential for enhancing the durability of concrete structures under severe environmental conditions, such as in bioreactive or chemically aggressive environments.