The concrete admixture content is generally not more than 5% of the cement mass.
Concrete admixtures refer to substances added to improve and adjust the performance of concrete. The application of concrete admixtures in engineering has received more and more attention. The addition of admixtures can play a certain role in improving the performance of concrete, but the selection, addition method and adaptability of admixtures will seriously affect its development.
Concrete admixtures are substances that are mixed in the process of mixing concrete to improve the performance of concrete. The mixing amount is not more than 5% of the cement quality (except for special circumstances).
Concrete admixtures are divided into four categories according to their main functions:
2.1 An admixture to improve the rheological properties of concrete mixtures. Including various water reducers, air-entraining agents and pumping agents.
2.2 The admixture that adjusts the setting time and hardening performance of concrete. Including retarder, early strength agent and accelerator, etc.
2.3 Additives to improve the durability of concrete. Including air-entraining agents, waterproofing agents and rust inhibitors.
2.4 Additives to improve other properties of concrete. Including air entraining agent, expansion agent, coloring agent, antifreeze agent, waterproof agent and pumping agent.
The initial use of admixtures was just to save cement. With the development of construction technology, admixtures have become the main measure to improve the performance of concrete.
Thanks to the superplasticizer, high-fluidity concrete, self-compacting concrete, and high-strength concrete are used; thanks to the thickener, the performance of underwater concrete is improved: thanks to the retarder, the setting time of cement is prolonged , It is possible to reduce the slump loss and extend the construction operation time: because of the antifreeze, the freezing point of the solution can be lowered, or the ice crystal structure will not cause frost damage, and then it is possible to carry out construction at negative temperature.