Carboxylic acid copolymer concrete slump retaining agent

Abstract

The invention discloses a carboxylic acid copolymer concrete slump retaining agent. The slump retaining agent is a copolymer which has the molecular weight of between 10,000 and 100,000 and is synthesized by using modified polyester, unsaturated carboxylic acid and cross-linking agent and by adopting a redox system and an initiator; 30 percent liquid alkali is added into the copolymer at the temperature of 45 DEG C to neutralize the copolymer and the concentration of the neutralized solution is diluted to 45 percent by softened water, and the pH value of the mixed solution is controlled to be between 6.0 and 7.0. Compared with the prior art, the slump retaining agent is directly prepared by polymerization which is performed by using the modified polyester, the unsaturated carboxylic acid and the cross-linking agent and by adopting the redox system and the water soluble initiator, activated macro-monomers of esters are not required to be prepared, the process is simple and the reaction temperature is low. The slump retaining agent has a good plastic retaining effect on middle and low slump concrete or high slump concrete and does not prolong the setting time of the concrete. Meanwhile, the cross-linking agent contained in the structure has a slow-release effect under the action of a strongly alkaline cement environment and slowly releases dispersive low-molecular polymers, so the problem of slump loss of the concrete is effectively solved.

Description

technical field [0001] The invention belongs to the field of concrete admixtures, in particular to a carboxylic acid copolymer concrete slump-retaining agent compounded with a polycarboxylic acid-based high-performance water reducer. Background technique [0002] With the rapid development of national infrastructure, especially the construction of high-speed railways in the next ten years, all require the use of high-performance concrete, and admixtures are not required to use traditional polycondensation products, such as naphthalene-based high-efficiency water reducers, melamine-based water reducers, Sulfamic acid-based water reducer. In order to meet the high durability requirements of high-performance concrete, the admixture requires the use of polycarboxylate-based high-performance water-reducers. Due to the late start of polycarboxylate water-reducers in my country, polycarboxylate water-reducers are widely available in the market The problem of large concrete slump lo...

AI Technical Summary

Problems solved by technology

[0005] 1. A large number of retarding components are used, but due to the excessive use of retarders, the concrete setting time is often too long, which affects the construction progress and project quality

Especially due to excessive retardation, if moisture protection measures are not taken in time, the concrete surface is easy to crack

[0006] 2. Secondary addition of water reducing agent (adding water reducing agent after the commercial concrete mixer truck arrives at the construction site) is likely to cause over-mixing of concrete admixtures and affect the quality of concrete.

[0007] 3. A variety of polycarboxylate water-reducing agents are used in combination. Although the problem of concrete slump loss can sometimes be solved, the molecular structure of the water-reducing agent determines that it cannot solve most of the problems of concrete slump loss.