Preparation method for high-slump-retention polycarboxylate water reducer

Abstract

The invention discloses a preparation method for a high-slump-retention polycarboxylate water reducer. The preparation method comprises the following steps of: esterifying methoxylpolyethylene glycol monomethyl ethers with different molecular weights with methacrylic acid and a mixed polymerization inhibitor for a period of time under the action of a catalyst and at a certain temperature, then adding allyl alcohol in one time, further esterifying in the same conditions to obtain an esterified macromonomer MP containing crosslinking monomer allyl methacrylate; then performing aqueous solution polymerization on the MP, unsaturated sulfonate, (meth)acrylate unsaturated monomers and a chain transfer agent in a low-temperature condition and within a redox initiation system; and finally adding caustic soda liquid to neutralize, so as to obtain the polycarboxylate water reducer with a certain concentration. The high-slump-retention polycarboxylate water reducer prepared by the preparation method disclosed by the invention is a high-performance water reducer which is prepared at a low temperature by virtue of a molecular structure design, as well as is high in slump retention, excellent in dispersing performance, good in adaptability, simple in process, pollution-free, low in energy consumption, and easy to realize industrialized production.

Description

technical field [0001] The invention belongs to the technical field of building materials, and in particular relates to a preparation method of a high-slump polycarboxylate water reducer. Background technique [0002] With the country's increasing efforts in infrastructure construction, the demand and performance requirements for concrete are increasing year by year. Similarly, the demand for high-performance water-reducing agents with the advantages of high water-reducing rate, low dosage, low alkali content, and environmental friendliness is also increasing. As an important raw material in concrete—concrete high-efficiency water reducer has become an indispensable new material for national capital construction. [0003] Although the excellent water-reducing performance of polycarboxylate superplasticizers has been widely recognized by the industry, due to factors such as changes in cement, mud content in sand, and stone materials, polycarboxylate superplasticizers have al...

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Problems solved by technology

[0003] Although the excellent water-reducing performance of polycarboxylate superplasticizers has been widely recognized by the industry, due to factors such as changes in cement, mud content in sand, and stone materials, polycarboxylate superplasticizers have also appeared in practical applications. Problems such as excessive slump loss and poor workability

Moreover, with the increasing urban congestion, it often takes 1-2 hours for fresh concrete to be transported to the construction site. In high temperature weather, the hydration rate of concrete accelerates, resulting in significantly faster adsorption of admixtures, resulting in excessive loss of fresh concrete. Pouring, a great waste of manpower and material resources

There are mainly two factors that affect the slump retention of polycarboxylate superplasticizers: synthesis and compounding. The synthesis depends on its molecular structure, such as the composition of structural units, graft density, molecular weight and its distribution. In addition to the type of monomer, it also depends on the choice of synthesis process and the control of parameters; compounding mainly adopts the method of adding slump retaining agent and retarder. The disadvantage of this method is that the cost of slump retaining agent is high and the setting time Excessive extension, etc.

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