The selection of admixtures should be determined through trial-matching tests according to the engineering materials and construction conditions. Various admixtures have their own characteristics. When used, they should be used according to the characteristics of the admixture and combined with the purpose of use, such as saving cement, improving concrete performance, accelerating the turnover of formwork and other comprehensive indicators, that is, determining the admixture through technical and economic comparisons. The variety of use.
2. Analysis of several concrete application admixtures
(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 in the concrete, block the leakage channels, and apply water-reducing agents and air-entraining agents.
(2) The key to mass concrete construction technology is to ensure a good combination of layered concrete during initial setting, reduce temperature rise during concrete hardening, and avoid concrete cracking. The use of retarding water reducer can meet the above requirements. , That is to retard the setting and reduce the temperature rise during the hardening of the concrete, thereby improving the quality of the 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. A high-efficiency water-reducing agent should be selected. It can greatly reduce the unit water consumption and increase the strength of concrete.
