Cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent and preparation method thereof

The invention belongs to the technical field of concrete water-reducing agents, specifically to a cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent and a preparation method thereof. The preparation method provided by the invention comprises the following steps: subjecting an unsaturated double bond containing terminated cross-star-shaped structure core, an unsaturated macromonomer, an unsaturated carboxylic acid monomer and water to mixing, then carrying out heating, adding an initiator and a chain transfer agent, carrying out a heat-preserving reaction, and carrying out cooling and neutralizing so as to obtain the cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent. The cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent provided by the invention uses a hyperbranched molecule as a core and a comb-shaped structure as an arm, so properties of the hyperbranched molecule and a comb-shaped polycarboxylic-acid water-reducing agent are obtained, and good slow-release and slump-retaining performances are achieved; the cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent is based on electrostatic interaction and steric hinderance effect, so excellent dispersibility to concrete is obtained; an ester group of the cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent is gradually hydrolyzed, so a slow-release effect is achieved; and the cross-star-shaped slow-release slump-retaining type polycarboxylic-acid water-reducing agent is applied to concrete and construction industry, and has low dosage, high water reducing rate, excellent dispersibility, good slow-release and slump-retaining performances, and extensive application prospects.