Brief Introduction to concrete admixtures

Brief Introduction to concrete admixtures

Keywords

Concrete admixtures, polycarboxylate superplasticizer, accelerator, amorphous calcium aluminate

Concrete admixtures are materials added before or during concrete mixing to improve the properties of fresh concrete and (or) hardened concrete. These admixtures can significantly improve certain properties of concrete, such as workability, strength, durability, etc., and the dosage is generally not more than 5% of the amount of cement. According to their main functions, concrete admixtures can be divided into the following categories:

Admixtures that improve the rheological properties of concrete mixtures:

Water reducers: including ordinary water reducers and high-efficiency water reducers, which can reduce the amount of mixing water and improve the fluidity and strength of concrete.

Air entraining agent: introduces a large number of evenly distributed tiny bubbles to improve the workability and frost resistance of concrete.

Pumping agent: improves the pumping performance of concrete and is suitable for large-scale mechanized construction.

‌Admixtures for adjusting the setting time and hardening properties of concrete:

‌Retarder: Extends the setting time of concrete, suitable for large-volume concrete and high-temperature construction.

‌Early strength agent: Accelerates the early strength development of concrete, suitable for rapid construction.

‌Fast setting agent: Makes concrete set and harden quickly, suitable for emergency repair projects.

‌Admixtures for improving the durability of concrete:

‌Air entraining agent: Improves the frost resistance and impermeability of concrete.

‌Waterproofing agent: Improves the water penetration resistance of concrete.

‌Rust inhibitor: Prevents the corrosion of steel bars in concrete.

‌Admixtures for providing special properties to concrete:

‌Antifreeze agent: Allows concrete to harden normally at low temperatures.

‌Expansion agent: Makes concrete expand to a certain volume, suitable for compensating for shrinkage.

‌Colorant: Used to prepare concrete with a specific color.  Each admixture has its specific mechanism of action and scope of application. By rationally selecting and using admixtures, various properties of concrete can be effectively improved, and the quality and durability of the project can be improved.