Preparation method of slump-preserving polycarboxylate water reducer

Abstract

The invention discloses a preparation method of a slump loss resistant polycarboxylate water reducer. The preparation method comprises the following steps: (1) preparing a polycarboxylate water reducer prepolymer: carrying out oxidation-reduction free radical polymerization reactions between unsaturated alpha-haloketone micro-monomers and unsaturated macro-monomers in the presence of an initiator, a reducing agent, and a chain transfer agent so as to obtain a polycarboxylate water reducer prepolymer containing alpha-haloketone; and (2) carrying out Favorskii rearrangement between the polycarboxylate water reducer prepolymer containing alpha-haloketone and an alkali to generate carboxylic acid / carboxylate, adjusting the pH value to 5-6, and adding water to obtain the slump loss resistant polycarboxylate water reducer. The prepared slump loss resistant polycarboxylate water reducer has the advantages that the adaptability between the water reducer and cement is good, the dispersibility of cement is improved, the water reducing performance is strong, and the slump loss resistant performance is strong too.

Description

technical field [0001] The invention relates to the technical field of a polycarboxylate water reducer for cement concrete, in particular to a preparation method of a slump-preserving polycarboxylate water reducer. Background technique [0002] Polycarboxylate water reducer, as a new type of high-performance water reducer following the aliphatic, naphthalene and sulfamate-based water reducers, because of its low dosage, high water-reducing rate, and adjustable molecular structure Excellent properties such as strong tonality and green environmental protection, are more and more widely used in a series of concrete projects such as high-speed railways, bridges, tunnels, dams, etc., but in the face of domestic complex and changeable cement and concrete materials, polycarboxylate Water reducers often do not reflect the advantages of their high performance. With the reduction of high-quality sand and gravel resources in our country, the complexity of concrete components has incre...

AI Technical Summary

Problems solved by technology

[0002] Polycarboxylate water reducer, as a new type of high-performance water reducer following the aliphatic, naphthalene and sulfamate-based water reducers, because of its low dosage, high water-reducing rate, and adjustable molecular structure Excellent properties such as strong tonality and green environmental protection, are more and more widely used in a series of concrete projects such as high-speed railways, bridges, tunnels, dams, etc., but in the face of domestic complex and changeable cement and concrete materials, polycarboxylate Water reducers often do not reflect their high performance advantages

With the reduction of high-quality sand and gravel resources in our country, the complexity of concrete components has increased. In the ready-mixed concrete industry, the slump loss of freshly mixed concrete has always been a problem that plagues engineering construction, especially long-term transportation will cause concrete to slump. Excessive loss of strength will affect the workability of concrete

It can effectively solve the compatibility problem between sand and gravel materials with large mud content and water reducing agent, but its reaction raw materials are many, the synthesis process is complicated, and the effect is greatly affected by temperature and pH

[0004] Chinese patent CN102153711A reports a macromer of allyl sulfonate monomer, acrylic acid monomer, polyethylene glycol monomethyl ether methacrylate and maleic anhydride grafted β-cyclodextrin A retarded polycarboxylate superplasticizer is obtained through free radical copolymerization, so that the obtained polycarboxylate superplasticizer has better retarding performance, micro air-entraining performance and better flow performance, but this The inventive maleic anhydride grafted β-cyclodextrin macromonomer has a low graft rate and is greatly affected by temperature, so it cannot fundamentally solve the problem of concrete slump loss under different conditions, which is not conducive to large-scale production and application

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