Anti-cracking shrinkage-reducing type polycarboxylate superplasticizer and preparation method thereof

Abstract

The invention discloses an anti-cracking shrinkage-reducing polycarboxylic acid water reducer and a preparation method thereof. The weight-average molecular weight (Mw) of the anti-cracking shrinkage-reducing polycarboxylic acid water reducer is 10,000-100,000, and the structural formula of the anti-cracking shrinkage-reducing polycarboxylic acid water reducer is shown in the specification. The preparation method comprises the following steps: (1) introducing an unsaturated double-bond structure on the structure by taking gallic acid as a raw material to prepare a gallic acid derivative unsaturated small monomer, carrying out free radical copolymerization reaction on the water reducing agent prepolymer and carbonyl-containing unsaturated acid and derivative monomers thereof to obtain a water reducing agent prepolymer; (2) introducing a hydrophilic polyether side chain on the gallic acid derivative of the prepolymerization product to prepare the shrinkage-reducing polycarboxylic acid water reducer with excellent performance. The anti-cracking shrinkage-reducing type polycarboxylate superplasticizer prepared by the preparation method disclosed by the invention is good in stability and suitable for being stored under various extreme weather conditions; the dispersing effect in concrete is good, the shrinkage reducing effect is excellent, and cracking conditions caused by various types of shrinkage can be obviously controlled and retarded.

Description

technical field [0001] The invention relates to the field of polycarboxylate water-reducer for concrete, in particular to an anti-crack and shrinkage-reducing polycarboxylate water-reducer and a preparation method thereof. Background technique [0002] Polycarboxylate superplasticizers are now widely used in projects such as railways, bridges and houses. In terms of these infrastructure constructions, the market has higher and higher requirements for additives. However, due to unavoidable factors, concrete is prone to cracking during early hardening and later use, which affects its durability. At present, a series of protective measures have appeared on the market to deal with the cracking of concrete, such as improving the adhesive material components, adding expansion agents, mixing synthetic fibers, and formulating specific curing techniques for specific environments. However, from a comprehensive point of view, adding concrete shrinkage reducer is the simplest and most ...

AI Technical Summary

Problems solved by technology

[0004] Represented by Japan and the United States, some shrinkage reducers such as alcohols, ethers, and alcohol amines were reported in the early stage. Such shrinkage reducers have no water-reducing effect, and the required dosage is high, and they will also have side effects of reduced strength in the later stage. , which limits their use

For domestic research, patent CN103724567A discloses a shrinkage-reducing polycarboxylate water reducer and its preparation method. The preparation method is free radical polymerization after esterification. surface tension, but the esterification reaction used in it needs to be carried out at a high temperature for a long time, which also greatly reduces the feasibility of industrial production; A shrinkage-reducing water-reducer prepared by free-radical polymerization of polyoxyethylene / polyoxypropylene polydimethylsiloxane maleate and a shrinkage-reducing water-reducer and a synthetic method thereof, and the dispersion of the shrinkage-reducing water-reducer to concrete The impact on the slump retention performance is small, but the 28-day shrinkage rate is smaller than the relative benchmark, which lacks market competitiveness

Images