Misconception 2: Concrete admixtures are used arbitrarily without considering the actual situation of the project
1. The purpose of use should be considered when selecting admixtures. When selecting admixtures, they should be determined through trial mixing tests based on engineering materials and construction conditions. Various admixtures have their own characteristics. When using them, they should be based on the characteristics of the admixtures and the purpose of use, such as considering comprehensive indicators such as saving cement, improving concrete performance, and accelerating formwork turnover, that is, determining the type of admixture to be used through technical and economic comparisons.

2. Analysis of the application of admixtures in several concretes (1) The purpose of applying admixtures to waterproof concrete is to improve the impermeability of concrete. To improve the impermeability of concrete, the key is to reduce the pores inside the concrete, block the leakage path, and apply water reducers and air entraining agents. (2) The key to large-volume concrete construction technology is to ensure good bonding between layered concrete during initial setting, reduce the temperature rise during the concrete hardening process, and avoid concrete cracking. The use of slow-setting water reducers can meet the above requirements, that is, slow setting and reduce the temperature rise during the concrete hardening process, thereby improving the quality of concrete. (3) In large-span prestressed concrete structures, the self-weight of the structure is often the main contradiction. Therefore, the purpose of using admixtures is to prepare high-strength concrete, reduce the weight of the structure, and effectively utilize the stress of high-strength steel bars. It is advisable to use high-efficiency water reducers, which can greatly reduce the unit water consumption and improve the strength of concrete.