Views: 10 Author: su Publish Time: 2018-11-13 Origin: Site
The polycarboxylate superplasticizer is designed according to the mechanism of dispersing cement to design an effective molecular structure to prevent concrete slump loss without causing significant retardation, high plasticizing effect, good fluidity and cement adaptation. Sexuality, concrete reinforcement effect is remarkable, reducing concrete shrinkage, extremely low content of harmful substances and other technical performance characteristics, thus giving concrete more excellent construction workability, good strength development, excellent durability, and good comprehensive technical performance advantages. And environmental protection features, in line with the needs of modern concrete engineering. Therefore, polycarboxylate superplasticizers are becoming the preferred admixture for the preparation of high performance concrete.
Engineering practice has proved that it is difficult to meet the construction requirements of high performance and multi-functionality with a single type of water reducing agent. Due to the differences in the composition of different types or types of water reducers, their application performance varies. Therefore, the compounding technology of water reducing agent has achieved unprecedented development and achieved good application results. Compounding (blending) technology (modification) of water reducing agent, that is, adding some fillers, additives, etc. in proportion. Preparation of polycarboxylic acid ester ether compound water reducing agent mother liquor and cement hydration process, the purpose is Improve the performance of the original water reducing agent or form a polymer system with new properties. Common compounding systems include water reducing agents (naphthalene, melamine, sulfamic acid, ester and etheric polycarboxylic acids), defoamers, air entraining agents, and the like. Polyester and polyether polycarboxylate superplasticizers have their respective advantages in terms of their preparation process and properties. The polyester type high performance water reducing agent has higher water reducing efficiency, and the fly ash has better adaptability, but the solid content is low, there is bleeding, and the loss over time is large. In addition, the synthesis process of the polyester type water reducing agent is complicated, and the esterification step is more than the polyether type water reducing agent, and the synthesis cost is high. The polyether type water reducing agent has high solid content, and has the advantages of low dosage, high water reduction rate, low cost, and small loss of time, but the adaptability is not good, and the raw material maleic anhydride is not easy to be polymerized. Polycarboxylate superplasticizer is a kind of cement dispersant used in cement concrete. The early development of the product is a polyester structure with a main chain of methacrylic acid, a side chain of carboxylic acid groups and MPEG. A polyether-type structure in which the main chain is a polymerized acrylic acid and a side chain is a polyether, and the polycarboxylic acid water reducing agent is a hydrophilic long side chain having a certain length and number and a main group having a strong polar active group A special molecular structure surfactant composed of chains. In the wetting environment, the polycarboxylate water-reducing agent product has a plurality of side chain-supported outwardly extending comb-tooth structures which provide sufficient spatial alignment effect for further dispersion of cement particles, enabling cement dispersibility and retention time. Different from other types of water reducing agent to meet the concrete construction fluidity and retention time. The structural diversity of polycarboxylate superplasticizers makes the development and development of such products more meaningful. The polyether type water reducing agent can be synthesized by using a polyether monomer, a plurality of functional groups to assist the main chain design, and a change in the production process to obtain a variety of excellent mother liquor products. The compounding scheme of the polycarboxylic acid water reducing agent includes the combined use of different mother liquors of the polycarboxylic acid water reducing agent, and the functional components of the polycarboxylic acid mother liquor and retarding, deflation, defoaming, state regulation, and mud resistance. Physical compounding. The combination of the mother liquor and the different functional mother liquors is the basis of the compounding technique, followed by additional functions. The fines are fine-tuned to obtain satisfactory concrete properties.