Novel melamine water reducer and preparation method

Abstract

The invention relates to a novel melamine water reducer which comprises the following raw materials by mass: 18.7-23.2% of melamine, 38-42.6% of formaldehyde, 20-27% of sodium bisulfite, 2-3% of sulfuric acid, 3-5% of liquid alkali, and 20-30% of water. The method of the invention comprises the following steps: adding water, melamine, the formaldehyde solution into a reaction vessel, stirring and heating to 50-60 DEG C for reaction for 1-3 hours, performing heat preservation and reaction at 60-75 DEG C for 1-5 hours, adjusting the pH of the solution to 8.5-9.5 by the liquid alkali solution; adding sodium bisulfite, heating, reacting at 84-90 DEG C for 1-3 hours, maintaining the pH at 10-11; finally cooling the solution to 50 DEG C, adjusting the pH value to 5-6.5 by 30% sulfuric acid, continuing the reaction for 1-2 hours, neutralizing the solution to obtain a pH of 7, discharging to obtain the finished product. The water reducer prepared by the invention has strong water retention capacity for concrete, a high water-reducing rate, high early strength of concrete, low air entraining, and less slump loss.

Description

technical field [0001] The invention relates to the technical field of concrete admixtures, in particular to a novel melamine water reducer and a preparation method thereof. Background technique [0002] Cement concrete is the most used building material in the world, but cement concrete has weaknesses such as heavy weight, low strength and brittleness. With the rapid development of the construction industry, new requirements have been put forward for the performance of concrete in various aspects, such as improving the strength of concrete and improving the slump loss during the transportation of concrete. Ordinary concrete has been difficult to meet the new construction technology requirements. Adding admixtures to concrete is an effective, convenient and economical method to increase concrete strength and improve various properties of concrete. Water reducer is the most widely used admixture in concrete. [0003] With the development of the concrete admixture industry,...

AI Technical Summary

Problems solved by technology

As far as the country is concerned, in order to meet different construction requirements, the admixture industry still generally adopts the method of compounding, and there are still few single high-efficiency water reducers with high performance and multiple functions.

At present, the types of domestic superplasticizers mainly include: polycarboxylate superplasticizers, sulfamate superplasticizers, and naphthalenesulfonate superplasticizers. There are also problems of varying degrees: although the polycarboxylate high-efficiency water-reducing agent has a high water-reducing rate, it is sensitive in response and difficult to control during construction; due to the molecular structure of the sulfamate high-efficiency water-reducing agent, concrete bleeding is serious, It is difficult to guarantee the quality of the project; naphthalenesulfonate superplasticizer is the most commonly used superplasticizer, and the low-concentration product naphthalenesulfonate superplasticizer contains as much as 20% sodium sulfate, which is easy to precipitate and cause plugging at low temperature pipes, which have a greater impact on engineering construction

However, compared with the previous melamine high-efficiency water-reducing agent, its water-reducing and water-retaining effects are not significantly improved

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