Many staff who do not understand the construction chemical industry said: Testing the effectiveness of concrete admixtures requires repeated tests based on actual local floor materials, etc., which is affected by raw material quality, environmental changes and Affected by various factors such as local temperature changes, current concrete generally has poor initial fluidity, large slump loss, shrinkage and cracking, etc. Concrete admixtures have problems with poor adaptability, which can be determined from the structure-activity relationship of admixture molecules. Solve the problems of high dispersion, high adaptability, fast dispersion, fluidity maintenance, shrinkage reduction and crack resistance of concrete.
The main formulas of ordinary pumping admixtures are admixture masterbatch, retarder, air-entraining agent, etc. The specific formula should be determined through experiments based on your local raw materials and your construction requirements. Local differences vary greatly. Generally, masterbatch manufacturers will produce finished products. You can ask the masterbatch manufacturer to provide you with the formula. You can make more experiments and make specific adjustments. Retarder generally uses sodium gluconate, sugar, etc.
The key technologies involved are as follows:
1. High dispersion key technology
High water-reducing polymer additives increase the steric hindrance effect and are effective Improve the adsorption characteristics, increase the saturated adsorption capacity, and increase the ultimate water reduction to more than 50%, providing technical support for low water-binder ratio and ultra-high-strength concrete.
2. Highly adaptable key technologies
Highly adaptable polymer admixtures increase the preferential adsorption driving force and weaken hydrogen bonds to solve the problem of high mud content and SO42- content in aggregates. The problem of insufficient initial fluidity of concrete under certain conditions.
3. Fast-dispersing key technology
Fast-dispersing viscosity-reducing polymer concrete admixture increases charge density, improves initial adsorption driving force, increases multi-branched long side chains and increases water film Layer thickness, viscosity-reducing monomer reduces solution viscosity, solving the problems of slow initial dispersion and high viscosity of complex component concrete with low water-binder ratio (W/B=0.18) and large amounts of industrial waste residue (more than 50%).
4. Key technologies for fluidity maintenance
The long side chain (M=2000~5000) of the high-temperature and long-term slump-preserving admixture can reduce early hydration and burial. The side chains quickly compensate for high-temperature losses, and the slow-release group main chain continuously compensates for long-term losses, achieving multi-stage regulation of the fluidity of complex component concrete in high-temperature environments; the hydrophilic network of medium-low slump slump-preserving admixtures Cross-linking technology reduces the sensitivity to water consumption and gradually hydrolyzes to provide slump protection. The rapid release of rapidly hydrolyzable polyether monomers makes up for early losses, meeting the special needs of maintaining the fluidity of nuclear power and hydropower concrete.
5. Key technologies for reducing shrinkage and cracking The structure-activity relationship clarifies the regulation mechanism of single-molecule membrane assembly: micelle demulsification and emulsifier collaborative migration and aggregation.
The "narrow" emulsifier of the evaporator improves the film-forming rate and the density of the monomolecular membrane, and the highly elastic long side chain amphiphilic compound improves the stability of the monomolecular membrane and effectively inhibits the formation of monomolecular membranes under complex and harsh conditions. The evaporation of concrete water can effectively reduce the risk of plastic cracking and provide solutions to the plastic cracking and encrustation problems of high-performance concrete under high temperature, low humidity and strong wind conditions
6. Special polyether key technology
The above five key technologies all rely on the application of special polyethers to achieve multi-element heterogeneous catalysis, binary synergistic polymerization inhibition, efficient three-dimensional ultra-fine atomization, changing the molecular structure, breaking through the existing technical bottlenecks, and special-purpose The independent preparation of polyether has laid the foundation for the development of functional admixtures with excellent properties.
The successful development of concrete admixtures has solved the technical problem of maintaining medium slump in nuclear island thin-walled structures that are prone to cracking for nuclear power projects, such as Haiyang Nuclear Power Plant; and has solved the problem of high-temperature construction fluidity in summer for high-speed railway projects. Technical problems such as large losses, slow initial dispersion of large amounts of industrial waste residue, and high viscosity, such as the Beijing-Shanghai and Wuhan-Guangzhou high-speed railways; meet the comprehensive requirements of high water reduction, high slump protection, and low viscosity for bridge projects, such as the Hong Kong-Zhuhai-Macao Bridge; It also meets the requirements of normal concrete slump maintenance with low glue consumption and efficient dispersion and dispersion maintenance of complex component concrete in hydropower projects, such as Xiluodu, Jinping Hydropower Station, etc.
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