Research Progress and Prospect of Domestic Polycarboxylate Water Reducing Agents

Polycarboxylate superplasticizer can produce ideal water reduction and reinforcement effect when the dosage is low, less influence on concrete setting time, better slump retention, and adaptability to cement/mixture. It is relatively good, has little influence on the shrinkage of concrete does not use formaldehyde in the production process and does not discharge waste liquid, low content of sulfonate and chloride ion, etc. A new generation of water reducing agent after melamine, aliphatic and sulfamate water reducing agents. The polycarboxylic acid-based water reducing agent has a high water-reducing rate, excellent moisture retention performance, and good adaptability to cement, but its application range is limited due to its high price. By compounding, the price of the water reducing agent can be reduced, and some aspects of its performance, such as earlystrength,retardation, deflation, and defoaming, can be enhanced. The engineering community attaches great importance to compounding technology, and researchers have also done a lot of research to reveal the mechanism of the compounding action of water reducing agents.

As a new generation of water reducing agent, polycarboxylate water reducing agent is considered to have unparalleled performance as a water reducing agent such as naphthalene or lignin. It has a broad market prospect and is in the ascendant in the world. Based on the above summary of research on domestic polycarboxylate superplasticizers, this paper looks forward to the future research directions. The supply status of MPEG in the synthesis of macromonomers and water-reducing agents is basically dependent on imports, which increases the cost of polyester water-reducing agents in China to a large extent, thus realizing MPEG localization and localization. It is very important. At present, MPEG has national standards, and the stable supply of such monomers is a solid foundation for further research and production of high-quality polycarboxylic acid water reducing agents. The polyether water-reducing agent synthesized by TPEG is closer to the polyester water-reducing agent, and systematic research should be carried out. At the same time, we continue to explore the use of different macromonomers to synthesize water reducing agents to enrich the macromonomer source of polycarboxylate superplasticizers.

There are many researches on the synthesis process of polycarboxylate superplasticizers in China. On this basis, we continue to study and summarize the effects of various influencing factors in the synthesis, continuously optimize the synthesis process, seek the best industrial production conditions, and develop new synthetic processes. At present, the synthesis method for producing polycarboxylic acid-based water reducing agent is mainly free radical copolymerization. The synthesis conditions of this method are mild, but the distribution of various functional groups on the molecular main chain is uncontrollable and the molecular weight distribution is wide. Some domestic scholars began to try to synthesize water reducing agents by atom transfer radical polymerization , which inspired our research ideas; and domestically, aqueous solution polymerization, whether solvent polymerization can be considered. Compounding Compounding is the superposition of the properties of different components on the basis of mutual solubility of components, and it is necessary to solve both problems at the same time. Domestic research on the compounding of polycarboxylate superplasticizers mostly focuses on the selection of compound components, the amount of each component and the performance of the water reducing agent after compounding. There is no systematic compounding. The technique has not been studied in depth, so that the compounding has more empirical properties. Therefore, it is necessary to summarize the existing compounding techniques and deepen the research on the mechanism of compounding to meet various practical needs in the project. The relationship between the molecular structure of the polycarboxylate superplasticizer on the performance of concrete is mainly reflected in its influence on the hydration process of cement. At present, domestic research on the relationship between water-reducing agents mostly focuses on the relationship between molecular structure and concrete apparent properties. Therefore, future research can go deeper into "molecular-to-molecules." The level of water-repellent molecular structure affects cement hydration. In addition, in the preparation and application technology of polycarboxylate water reducer products, there are still many problems to be explored, such as the sensitivity of the effect of the water reducer on the cement/mixture, and the mixing of the water reducer. The sensitivity of the amount, the sensitivity to water consumption, and the sensitivity to the mud content of the aggregate. Only with the deepening of research work and the accumulation of application experience can these problems be finally solved, and the performance of products can be continuously improved and applied to a wider range of fields.