Mud-resistant and slump-retaining polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses a mud-resistant and slump-retaining type polycarboxylate superplasticizer. The method comprises the following steps: firstly, performing esterification reaction on maleic anhydride and 2-hydroxyphosphonoacetic acid under heating and stirring conditions to obtain a mud-resistant functional monomer; and then introducing a hydrophobic polyether macromonomer, acrylic acid and amethyl methacrylate monomer to carry out free radical polymerization. According to the mud-resistant and slump-retaining type polycarboxylate superplasticizer, the mud-resistant and slump-retaining properties of the obtained fresh concrete can be effectively guaranteed, and the workability and mechanical properties of the obtained fresh concrete are further improved; the applicability to cement types, gravel quality and the like is high, and technical support can be provided for application of the gobi material in the Xinjiang region in concrete; and the related preparation method is simple,mild in reaction condition, environment-friendly and suitable for popularization and application.

Description

technical field [0001] The invention belongs to the technical field of admixtures, and in particular relates to a mud-resistant and slump-retaining polycarboxylate water reducer and a preparation method thereof. Background technique [0002] Polycarboxylate superplasticizer has the advantages of low dosage, high water reducing rate, and strong designability of molecular structure. It has become one of the mainstream concrete admixtures in the world. However, with the rise of the construction industry and the rapid increase of infrastructure projects, the consumption of sand and gravel aggregates is huge, but high-quality sand and gravel resources are increasingly scarce, and the use of degraded sand and gravel resources faces problems such as large mud content and high impurity content in aggregates. In particular, the Gobi materials distributed in Xinjiang are usually mainly natural sand and pebbles, and the sand fault gradation phenomenon is serious, the pebbles are too la...

AI Technical Summary

Problems solved by technology

However, with the rise of the construction industry, infrastructure projects have increased dramatically, and the aggregate consumption of sand and gravel is huge. However, high-quality sand and gravel resources are increasingly scarce. The use of degraded sand and gravel resources is faced with problems such as large mud content and high impurity content in aggregates.

In particular, the Gobi materials distributed in Xinjiang are usually mainly natural sand and pebbles, and the sand fault gradation phenomenon is serious, the pebbles are too large (20-40mm), and the aggregate mud content is large (up to 19wt%), and the mud content is mainly Mainly montmorillonite and silty clay; when it is applied to the preparation of concrete mixture, it will absorb a large amount of admixtures and water, causing the volume of the concrete mixture to expand and turn into a paste, and the fluidity and workability will change. Poor, and the volume shrinkage is obvious after hardening and dehydration, and the strength is far lower than the design strength

Ordinary polycarboxylate superplasticizers are very sensitive to the mud content in sand and gravel. With the increase of mud content in sand and gravel, polycarboxylate superplasticizers are adsorbed by clay in large quantities during use, making polycarboxylate superplasticizers The dispersibility and dispersion retention ability of the water agent are reduced, resulting in a substantial decrease in the fluidity of the concrete, and an increase in the loss of slump and expansion over time

[0003] In response to the above technical problems, improvement measures such as increasing the dosage of polycarboxylate superplasticizers or introducing mud-repelling agents are usually adopted: traditional mud-resistant polycarboxylate superplasticizers are difficult to cope with the high-mud environment of Gobi materials in Xinjiang, and Poor adaptability, the dispersibility and slump retention performance of the superplasticizer in the mixture are severely reduced, and the mud in the aggregate will absorb a large amount of superplasticizer, which will cause the superplasticizer to lose its water reducing performance; increasing the dosage of superplasticizer will inevitably reduce It increases production and operation costs, and cannot substantially solve the problems of low water reducing rate and poor slump retention ability. On the other hand, it will also cause problems such as segregation, bleeding, and abnormal setting time of the concrete mixture; It will cause the performance of polycarboxylate superplasticizer to decline, and there will be problems such as poor compatibility with sand and gravel aggregates

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