The invention belongs to the technical field of building materials, and specifically relates to a polycarboxylic
acid water reducer with a high water-reducing rate and high
slump constant holding capacity, and its synthetic method and use method. The polycarboxylic
acid water reducer comprises 2-methallyl
polyoxyethylene ether (TPEG), 2-acrylamido-2-methylpropanesulfonic acid (AMPS),
methacrylic acid (MAA),
ammonium persulfate (APS),
sodium hydroxide and water. The synthetic method comprises the following steps that 1, TPEG, AMPS and MAA are prepared respectively into mixed solutions with concentrations in a range of 20 to 50%; 2, simultaneously, APS is added with a proper amount of water and is dissolved in the water; 3, the TPEG and AMPS
monomer mixed solutions prepared by the step 1 are added into a reactor;
nitrogen is fed into the mixture in the reactor; a condenser tube is mounted; the mixture is heated to a temperature of 60 to 100 DEG C with stirring; the MAA
monomer solution prepared by the step 1 and the APS solution prepared by the step 2 are respectively added dropwisely into the heated mixture, wherein dropwise addition time of the MAA
monomer solution is in a range of 1 to 5 hours and dropwise addition time of the APS solution is in a range of 1.5 to 5.5 hours; and after the dropwise addition is finished, the mixture with the MAA monomer solution and the APS solution undergoes a reaction at a constant temperature for 1 to 2 hours; 4, reaction products obtained by the step 3 are cooled and are neutralized by a NaOH solution to form desired products. The synthetic method of the polycarboxylic
acid water reducer is a one-step synthetic method and has simple processes. Products prepared through the synthetic method have the advantages of stable performances, low
doping quantity, high water-reducing rate, high
slump constant holding capacity and good market prospects.