Preparation method of viscosity-reducing type polycarboxylic acid water reducer

Abstract

The invention discloses a preparation method of a viscosity-reducing type polycarboxylic acid water reducer. The preparation method comprises the following steps: (1) adding 4-hydroxybutyl vinyl polyoxyethylene ether, phosphoric acid with a concentration of 85% and phosphorus pentoxide into a reaction container for a reaction in a temperature of 40 DEG C for 3-4 hours; (2) adding a proper amount of water, performing stirring for dissolution, adding part of unsaturated carboxylic acid monomers and controlling the pH value in a range of 4-5; (3) controlling the temperature in a range of 15-30 DEG C, adding an oxidant solution and performing full stirring; and (4) separately dropwise adding remaining unsaturated carboxylic acid monomers, unsaturated aromatic monomers, a mixed solution of fluorine-containing unsaturated monomers and a chain transfer agent, and a water solution of a reducing agent, after the adding, performing curing for at least 1 hour, and finally adding a water solution of sodium hydroxide for neutralization to obtain the polycarboxylic acid water reducer. The product provided by the invention can effectively reduce the thickness of the Stem layers on the surfaces of glue material particle dispersion, weaken the bridging effects between neighbouring dispersion, greatly reduce the backflow time of high-viscosity concrete, and improve the construction properties of concrete.

Description

technical field [0001] The invention belongs to the technical field of building admixtures, and in particular relates to a preparation method of a viscosity-reducing polycarboxylate water reducer. Background technique [0002] With the continuous expansion of the scale of civil engineering and the continuous improvement of the level of science and technology, some important buildings with high-rise large-span and special functional requirements continue to appear, such as skyscrapers, super-long-span bridges and giant water conservancy projects. High strength, better durability, and better stability, these demands have led to the gradual development of concrete from ordinary to high performance and even ultra-high performance. The improvement of concrete strength is mainly achieved by reducing the water-binder ratio, which also leads to higher viscosity of concrete, causing a series of construction problems such as concrete mixing, transportation, and pumping, which largely ...

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Problems solved by technology

However, when it is actually applied to high-strength concrete with low water-binder ratio, its effect is similar to that of polycarboxylate superplasticizers branched with polyethylene glycol monomethyl ether methacrylate, and it cannot be hydrolyzed well. The slump and fluidity are maintained; at the same time, due to the limited slump retention ability of methallyl polyoxyethylene ether, this product cannot really meet the requirements of high-strength concrete that needs to have excellent flow properties; and due to the double bond of raw materials Because of the activity and the initiation system, the temperature required for the polymerization reaction is also high, and it is impossible to achieve low temperature energy saving

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