Polycarboxylic acid, use thereof and water reducer containing same

Abstract

The invention provides polycarboxylic acid, use thereof and a water reducer containing the same, belongs to the technical field of cement additives and solves the problems of low water reduction rate and slump keeping performance of the conventional water reducer. The polycarboxylic acid is an irregular copolymer formed by polymerization of 50 to 80 weight percent of unsaturated polyether of a general formula below, 15 to 30 weight percent of unsaturated carboxylate or unsaturated carboxylate and 0 to 25 weight percent of third monomer which has unsaturated double bonds and polar groups, wherein R1 and R2 represent hydrogen atom or methyl; R3 and R5 represent oxyalkylene; R4 and R6 represent hydrogen atoms or C1 to C20 alkyl; a and c are integers between o and 3; b and d are 0 or 1; and m and n are integers between 10 to 50. The water reducer provided by the invention consists of 40 to 60 weight percent of polycarboxylic acid and the balance of water. The invention also discloses the use of the polycarboxylic acid in water reducer. The water reducer can be used high-strength concrete.

Description

technical field [0001] The invention relates to the technical field of cement admixtures, in particular to a polycarboxylic acid and its application, and a water reducer containing the polycarboxylic acid. Background technique [0002] Water reducing agent is an important cement admixture, which is mainly used to reduce mixing water consumption and improve strength under the condition of concrete workability and cement dosage unchanged. The first and second generation water reducers are lignosulfonate water reducer and naphthalene sulfonate-formaldehyde condensation product respectively. They can be adsorbed on the surface of cement particles to charge the surface of cement particles, thereby The repulsive force disperses the cement particles. [0003] Polycarboxylate water reducer is the third generation of water reducer, which has such as figure 1 In the "comb structure" shown, the "teeth" of the "comb structure" are side chains of polyether. Due to the "comb structure"...

AI Technical Summary

Problems solved by technology

But the preparation process of this polycarboxylate superplasticizer comprises the reaction of unsaturated polycarboxylic acid and polyamide polyamine, in this reaction, carboxylate radical is except the polyamide polyamine that reacts with primary amino group to generate double bond, also It may react with the primary amine groups at both ends of the polyamide polyamine at the same time to form a structure with double bonds at both ends, or react with the secondary amine groups in the chain to form a structure with multiple double bonds. These structures are easy to polymerize in the next step. Forms a gel, making the reaction fail, so its preparation is very difficult

[0008] The inventors have found that the prior art has at least the following problems: most of the existing polycarboxylate water reducers have poor slump retention, and it is difficult to prepare and use products with better slump retention

At the same time, with the development of technology, the requirements for the strength and durability of building structures are getting higher and higher, and the application of high-strength concrete is becoming more and more extensive. Poor, so the water-reducing agent used for high-strength concrete requires a higher water-reducing rate, but the water-reducing rate of the existing polycarboxylate water-reducing agent cannot meet the requirements of high-strength concrete

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