Preparation method for ester polycarboxylic acid slump retaining agent

Abstract

The invention discloses a preparation method for an ester polycarboxylic acid slump retaining agent. The method comprises the following steps: (1) performing esterification reaction; (2) performing copolymerization; (3) performing neutralization reaction. According to the preparation method disclosed by the invention, aliphatic hydroxyl esters, unsaturated anhydride esterified esterification products, unsaturated hydroxyl esters and unsaturated phosphate are copolymerized into the ester polycarboxylic acid slump retaining agent; the molecular structure simultaneously carrying carboxyl and dual ester group is introduced into a polycarboxylic acid molecular chain structure; the electrostatic repulsion effect of a water reducing agent is not influenced by the electronegative carboxylate radical; the problems of workability and sensitivity of the concrete can be solved; the dual ester group is hydrolyzed under an alkaline condition of cement paste and more carboxyl groups are slowly released, so that the slump retaining property of the concrete is improved; the unsaturated phosphate introduced into the molecular chain can endow the molecular chain with the phosphate radical; the phosphate radical has two negative charges and has higher adsorption capacity for cement, so that the competitive adsorption capacity with SO4<2-> in cement can be increased and the dispersity can be increased.

Description

technical field [0001] The invention belongs to the technical field of building admixtures, and in particular relates to a preparation method of ester polycarboxylic acid slump-retaining agent. Background technique [0002] With the rapid development of my country's economy and the improvement of construction level, the requirements for concrete quality are getting higher and higher. However, due to the wide variety of raw materials used in the production of concrete and the large regional differences, it is often easy to cause incompatibility between polycarboxylate superplasticizers and floor materials. In recent years, due to the gradual reduction of high-quality sand and gravel resources, a large amount of sand and gravel with high mud content is being increasingly used in concrete production. However, ordinary polycarboxylate superplasticizers are very sensitive to the mud content in sand and gravel, and the superplasticizer is easily absorbed by the soil, resulting in...

AI Technical Summary

Problems solved by technology

However, ordinary polycarboxylate superplasticizers are very sensitive to the mud content in sand and gravel, and the superplasticizer is easily absorbed by the soil, resulting in a decrease in the effective ratio of the water reducer that can function. The dispersion performance of the polycarboxylate superplasticizer and slump retention ability are significantly reduced, and the working performance of concrete is deteriorated

In addition, long-term transportation can also easily lead to excessive loss of concrete slump, which affects the construction performance of concrete, especially in hot weather seasons, the phenomenon of concrete slump loss is more obvious

In view of these problems, by increasing the amount of water-reducing agent or adding water to reshape the concrete before construction, the concrete can restore better working performance, but increasing the amount of water-reducing agent in the initial stage of mixing will cause concrete segregation and bleeding, which will affect the flexibility of concrete. and will greatly increase the production cost of concrete, while adding water will easily lead to an increase in the actual water-binder ratio of concrete, seriously affecting the strength of concrete, and may even cause quality accidents in concrete engineering