Preparation method of high-adaptability polycarboxylate superplasticizer suitable for low-quality aggregate

Abstract

The invention discloses a preparation method of a high-adaptability polycarboxylate superplasticizer suitable for low-quality aggregate. The high-adaptability polycarboxylate superplasticizer is prepared from an unsaturated polyoxyethylene ether monomer a, an unsaturated carboxylic acid monomer b and an unsaturated phosphate ester monomer c in a molar ratio of 1:(3.0-4.5):(0.5-1.0) under the action of a redox initiator and a chain transfer agent by carrying out an aqueous solution free radical polymerization reaction, wherein the dosages of the oxidant, the reducing agent and the chain transfer agent are respectively 0.4-1.2%, 0.1-0.5% and 0.2-0.8% of the total dosage of the monomer. The preparation method disclosed by the invention has the advantages of simple process, easily controlled conditions, short reaction time, low energy consumption and the like. The prepared high-adaptability polycarboxylate superplasticizer has extremely high adaptability when being applied to gravel aggregate with poor quality, high mud content and machine-made sand concrete, and shows excellent dispersing performance and slump retention capacity.

Description

technical field [0001] The invention belongs to the technical field of concrete water reducers for building materials, and in particular relates to a preparation method of a highly adaptable polycarboxylate water reducer suitable for low-quality aggregates. Background technique [0002] Polycarboxylate superplasticizer is a new generation of high-performance superplasticizer after lignosulfonate superplasticizer and naphthalene-based high-efficiency superplasticizer. It has the advantages of adjustable structure, green and environmental protection, and has been widely used in concrete. However, in recent years, the shortage of sandstone resources, quality deterioration, low-quality aggregates such as high mud content, high stone powder content, and poor gradation have greatly affected the dispersion and dispersion retention of polycarboxylate superplasticizers. Concrete workability is greatly reduced, slump and expansion are lost rapidly, and strength is reduced, which seri...

AI Technical Summary

Problems solved by technology

However, this method needs to use a large amount of expensive silane monomers as raw materials, which is costly and unfavorable for industrialization

[0005] At present, most of the polycarboxylate superplasticizers designed for high mud content natural sand and machine-made sand use vinyl alcohol 4C (methallyl polyoxyethylene ether HPEG) and 5C (isopentenyl polyoxyethylene ether) TPEG) macromonomer is synthesized, affected by the low reactivity of its unsaturated double bond, the polymerization reaction generally needs to be carried out under high temperature conditions. Although the redox agent initiating system realizes normal temperature polymerization, the reaction time is also up to 3-5h. The production cycle is long, the energy consumption is high, and the polycarboxylate superplasticizer synthesized by HPEG and TPEG is still difficult to solve the problem of poor workability of machine-made sand freshly mixed concrete

Images