Cement additives are materials added to the basic cement mix to enhance or alter the properties of cement during the hydration process. These additives can include a wide range of materials such as fly ash, silica fume, slag, and various chemicals designed to improve the workability, set time, strength, and durability of concrete. The use of additives is particularly crucial in severe environmental conditions, where enhanced properties such as increased resistance to freeze-thaw cycles, chemical attack, and heat are necessary for maintaining structural integrity and extending the lifespan of concrete structures.