Adding and mixing water to it harden this grey fine powder, and this is what makes it resistant to water and able to bare compressive strength, as well as resistant to sulphates that exist in soil, such as clay soil. In this type of cement it is necessary to decrease the ratio C3A less than 3.5%, because this component reacts with Ca SO4, which exists in soil or water. The result of this reaction is called Ettringite, which causes increasing in the concrete volume then causes cracks that lead to concrete failures.