Multifunctional carboxylic-acid comb-shape graft copolymer concrete superplasticizer

Abstract

The multifunctional super concrete plasticizing agent of carboxylic acid comb grafting copolymer is prepared through the water free radical copolymerization of the following monomers: monomer A with the general expression I in 10-40 wt%, monomer B with the general expression II in 30-70 wt%, monomer C with the general expression III in 10-50 wt%, monomer D with the general expression IV in 3-15 wt%, monomer F with the general expression VI in 0-15 wt%, and reactive defoaming agent E in 0.2-2 wt% of the sum of foregoing five kinds of monomer. The present invention can reduce the shrinkage of concrete, and has good adaptability on cement and admixture material, good dispersivity and slump maintaining performance, high weeping resistance and resolution resistance, small pumping drag, product yield near 100 % and no waste produced in the production process.

Description

technical field [0001] The invention relates to a multifunctional carboxylic acid comb-shaped graft copolymer that can be used as a concrete superplasticizer and a preparation method thereof, belonging to the technical field of concrete admixtures Background technique [0002] Concrete is a very widely used structural material in civil engineering, construction, water conservancy and many projects. In modern building construction, ready-mixed concrete has accelerated the construction progress and With the improvement of engineering quality, the application is becoming more and more common, and concrete superplasticizer is the fifth component that is indispensable for preparing ready-mixed concrete. [0003] Concrete superplasticizer, also known as high-efficiency water reducer, mainly plays three different roles in concrete production technology: ① Improve the workability of concrete construction, reduce physical labor intensity, and facilitate mechanization without changing...

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Problems solved by technology

EP1304314, US5911820, US6444780 use mercaptoethanol, dodecyl mercaptan and mercaptopropionic acid to prepare low-molecular-weight water-based polymers as chain transfer agents, but mercaptoethanol and dodecyl mercaptan have stench and pollute the environment, while mercaptopropionic acid is very expensive Expensive, and these substances do not function as necessary components of the product

In addition, polymerize in a water-isopropanol mixed solvent, and use isopropanol to control the molecular weight of the product. This method requires a cumbersome post-treatment process for removing isopropanol. The part of isopropanol remaining in the copolymer not only has Odor, and will affect the application performance of the product

[0009] In addition, a concrete superplasticizer with excellent performance must have both good dispersibility and good dispersibility retention ability. CN1261599 discloses the synthesis of ethyl vinyl ether-maleic anhydride copolymer in methyl ethyl ketone or tetrahydrofuran medium. Grafting with polyether in a dehydrating solvent, the product has good slump retention performance, but the dispersion performance is not good, and organic solvent is used as the reaction medium, which is not only uneconomical but also not conducive to environmental protection

[0010] CN1058474 has reported a kind of new dispersive composition that is used for the excellent slump loss characteristic of cement, and this composition is by alkenyl ether, dialkenyl ether and maleic anhydride as monomer, with Azobisisobutyronitrile is polymerized in toluene solvent as an initiator. The product has good slump retention ability, but the dispersion performance is not very satisfactory, and the production process is not conducive to environmental protection

[0011] EP0924174 has synthesized different polymers with two kinds of branched chains with different lengths. The polymer with long br...

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