Special cements are designed to meet the specific needs of particular engineering projects, and they possess a range of unique physical and chemical properties that make them excel in specific application areas. Here are some of the main characteristics of special cements:

1. **Low Heat of Hydration**: The hydration reaction of special cements generates less heat, making them suitable for large-volume concrete structures, such as dams and foundations, to reduce internal stress and cracks caused by heat.

2. **High Resistance to Sulfate Attack**: Certain special cements are designed to resist the erosion of sulfates, which is particularly important in coastal areas or regions with high sulfate content in the soil.

3. **Rapid Hardening and Early Strength**: These cements can harden quickly and develop early strength, suitable for projects that require rapid construction or work under adverse climatic conditions.

4. **Micro-Expansion**: Special cements may exhibit slight expansion during hardening, which helps reduce concrete shrinkage and improve its durability.

5. **High Impermeability**: Special cements have low permeability and can be used to prevent the penetration of water and harmful chemicals.

6. **Good Adhesion**: Special cements can adhere well to various substrates, including metallic and non-metallic materials.

7. **Chemical Resistance**: Special cements can resist the corrosion of a variety of chemicals and are suitable for the chemical industry and other applications requiring chemical resistance.

8. **Environmental Adaptability**: Special cements can be used under extreme temperature and humidity conditions, including in cold regions or high-temperature environments.

9. **Customizability**: Special cements can be customized according to specific engineering needs to meet particular performance requirements.

These characteristics of special cements make them an ideal choice for many critical engineering projects, but they also require professional knowledge to select and use correctly.