Polycarboxylic superplasticizer and application thereof

Abstract

The invention relates to a polycarboxylic superplasticizer. The polycarboxylic superplasticizer is prepared by copolymerizing a monomer A and a monomer B in the aqueous solution in the presence of a redox initiator and a chain transfer agent, wherein the molar ratio of the monomer A to the monomer B is 2 to 10: 1. The polycarboxylic superplasticizer is high in dispersing performance under lower amount of admixture, high in slump holding capacity and high in material adaptability, and can effectively avoid the shortcoming that common polycarboxylic superplasticizer is insufficient in slump holding capacity, so that the shortcomings that extra special slump holding agents for improving the concrete slump holding capacity are added and result in reduction of dispersion, reduction of economy and more difficulty in construction can be avoided.

Description

technical field [0001] The invention relates to a polycarboxylate cement concrete dispersant which has molecular structure activity in cement alkaline environment and thus has double-layer action driving force, and belongs to the technical field of concrete admixtures. Background technique [0002] In recent years, with the construction of large-scale infrastructure in the country, a series of major projects including large bridges, nuclear power, hydropower, super high-rise buildings and other major projects have put forward higher requirements for concrete, especially the construction time of high-performance concrete is increasing. Therefore, the fluidity retention ability of high performance concrete is particularly important. In addition, due to regional factors in China, there are large differences in the quality of building materials in different regions, and the quality of sand aggregates in the same region also fluctuates to a certain extent. These factors will cau...

AI Technical Summary

Problems solved by technology

These polymer molecules are adsorbed on the surface of cement particles through ionic bonds. Once adsorbed, they cannot be separated from the surface, and are gradually buried with the gradual generation of cement hydration products, so that the dispersion ability of polycarboxylate superplasticizer gradually increases. Loss, resulting in the reduction of concrete flow capacity, resulting in obvious loss of concrete slump

[0005] Conventional polycarboxylate dispersant can provide good dispersing ability due to its strong adsorption ability, but at the same time, it will inevitably cause insufficient number of remaining superplasticizer molecules in the concrete system, resulting in insufficient slump retention ability

At present, the most effective way to alleviate the fluidity loss of high-performance concrete mixed with polycarboxylate dispersants is to over-dope admixtures or add additional slump-retaining components. The cost of concrete is increased, and at the same time, the initial fluidity and later fluidity of concrete cannot be accurately controlled, thus increasing the difficulty of operation

In addition, because the conventional polycarboxylate dispersant mainly uses carboxyl group as the main adsorption group, it has great sensitivity to the sulfate ion and mud content introduced by the gypsum contained in cement and other components, thus reducing its effect. effects, especially reduced fluid retention

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