Search

CN-122010451-A - Composite additive for inhibiting ineffective adsorption of calcined clay on water reducer, and use method and application thereof

CN122010451ACN 122010451 ACN122010451 ACN 122010451ACN-122010451-A

Abstract

The application relates to the technical field of cement additives, in particular to a composite additive for inhibiting ineffective adsorption of calcined clay on a water reducer, and a use method and application thereof. The composite additive consists of a component A and a component B, wherein the component A is a biscationic sacrificial agent, and is prepared by reacting poly (N, N-dimethylallylamine) and tetrakis (hydroxymethyl) phosphonium sulfate in an aqueous solution at 60-80 ℃, and the component B is a polycarboxylic acid water reducer, and is prepared by carrying out free radical copolymerization on an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer and a phosphoric acid group-containing unsaturated monomer in the aqueous solution. According to the application, the synergistic effect of the component A biscationic sacrificial agent and the component B water reducer with a specific structure is utilized to strongly block ineffective adsorption of calcined clay on the water reducer, so that the dosage of the water reducer can be reduced, the initial fluidity and slump retention capacity of concrete are remarkably improved, the preparation process is mature, raw materials are easily available, and the method is suitable for large-scale industrial production and can be widely applied to green concrete.

Inventors

  • LAI HUAZHEN
  • CHEN HAO
  • WANG ZHAOPENG
  • GUO YUANQIANG
  • FANG YUNHUI
  • SHEN QIANG
  • ZHAO HUI
  • CHEN YIBIN

Assignees

  • 科之杰新材料集团有限公司

Dates

Publication Date
20260512
Application Date
20251223

Claims (10)

  1. 1. The composite additive for inhibiting ineffective adsorption of calcined clay to the water reducer is characterized by comprising a component A and a component B; the component A is a biscationic sacrificial agent, and is prepared by reacting poly (N, N-dimethylallylamine) with tetrakis (hydroxymethyl) phosphonium sulfate in an aqueous solution at 60-80 ℃; the component B is a polycarboxylic acid water reducer, and is prepared by carrying out free radical copolymerization on a monomer mixture through an aqueous solution, wherein the monomer mixture comprises an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer and an unsaturated monomer containing a phosphate group.
  2. 2. The composite additive according to claim 1, consisting of component a and component B; The component A is a biscationic sacrificial agent, which is prepared by reacting poly (N, N-dimethylallylamine) with phosphorus tetrahydroxymethyl sulfate in an aqueous solution at 60-80 ℃ and cooling, wherein the dry basis mass ratio of the poly (N, N-dimethylallylamine) to the phosphorus tetrahydroxymethyl sulfate is 1:0.20-1:0.35; Under the action of an initiator, a reducing agent and a chain transfer agent, the component B is prepared by the reaction of an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer and an unsaturated monomer containing a phosphate group at 15-40 ℃ through the free radical copolymerization of an aqueous solution.
  3. 3. The composite admixture according to claim 1 or 2, wherein the preparation process of the a-component comprises the steps of: Preparing a base material, namely mixing poly (N, N-dimethylallylamine) with deionized water, heating to 40-50 ℃, stirring for dissolution, and adjusting the pH of a system to 7.5-8.5; preparing a dripping solution, namely mixing the tetra-methylol phosphate deionized water; The reaction is that the dropping liquid is dropped into the base material for 1.5 to 2 hours, and the reaction is carried out for 1.5 to 2 hours at the temperature of 60 to 80 ℃ after the completion of the dropping.
  4. 4. The composite admixture according to claim 1 or 2, wherein the component B is a polycarboxylic acid water reducing agent having a polymer molecule containing structural units derived from an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer and a phosphoric acid group-containing unsaturated monomer.
  5. 5. The composite admixture according to claim 1 or 2, wherein, The unsaturated polyether macromonomer is at least two of isopentenyl alcohol polyoxyethylene ether, methyl allyl polyoxyethylene ether and ethylene glycol monovinyl polyethylene glycol ether, and the molecular weight is 1200-6000; the unsaturated carboxylic acid monomer is at least one of acrylic acid, methacrylic acid, methyl methacrylate and dimethylaminoethyl methacrylate; the unsaturated monomer containing the phosphate group is one or a combination of more of methacryloxyethyl phosphate and vinyl phosphonic acid.
  6. 6. The composite additive according to claim 1 or 2, wherein the unsaturated monomer containing a phosphate group accounts for 15% -35% of the total mass of the unsaturated carboxylic acid and the unsaturated monomer containing a phosphate group.
  7. 7. The composite admixture of claim 1 wherein the preparation of component B comprises the steps of: preparing a base material, namely mixing an unsaturated polyether macromonomer with deionized water; the first drip is prepared by mixing unsaturated monomer containing phosphate group with deionized water; preparing a second drop, namely mixing unsaturated carboxylic acid monomers with deionized water; the third drip preparation, namely, dissolving an initiator, a reducing agent and a chain transfer agent in deionized water; the copolymerization reaction is carried out, namely, a first drop, a second drop and a third drop are synchronously added at 15-40 ℃, the temperature is kept for curing for 0.5-1 hour after the addition, and the pH is regulated to 5-7.0 after the cooling, thus obtaining the copolymer; the total adding time of the unsaturated monomer containing the phosphate group is more than 80% of the total adding amount of the unsaturated monomer containing the phosphate group within the first third of the total adding time, and the total adding time is 1.5-3 h.
  8. 8. The composite additive according to claim 1 or 2, wherein the mass ratio of the unsaturated polyether macromonomer to the unsaturated carboxylic acid monomer is 200 (10-20).
  9. 9. A use method of a composite additive for inhibiting ineffective adsorption of calcined clay to a water reducer is characterized in that, In the concrete mixing process, firstly pre-mixing the component A in the composite additive according to any one of claims 1-8 with mixing water and a cementing material for 30-60 seconds, and then adding the component B to continuously stir uniformly; wherein the folding and solidifying doping amount of the component A is 0.05-0.2% of the total mass of the cementing material, and the folding and solidifying doping amount of the component B is 0.1-0.25% of the total mass of the cementing material.
  10. 10. Use of a composite admixture according to any one of claims 1 to 4 in green concrete.

Description

Composite additive for inhibiting ineffective adsorption of calcined clay on water reducer, and use method and application thereof Technical Field The application relates to the technical field of cement additives, in particular to a composite additive for inhibiting ineffective adsorption of calcined clay on a water reducer, and a use method and application thereof. Background Under the driving of the 'two carbon' strategy, calcined clay is increasingly widely used as an auxiliary cementing material in concrete, and can reduce the cement consumption and carbon emission. However, the layered silicate minerals (such as montmorillonite) remained in the calcined clay have extremely strong adsorption performance, and can generate strong ineffective adsorption on the polycarboxylic acid water reducer (PCE) molecules, so that the water reducer cannot fully play a role in dispersion, the workability of concrete is seriously deteriorated, and the consumption of the water reducer has to be greatly increased to ensure the workability of the concrete, and the cost is greatly increased. In the existing schemes, the schemes for coping with the problem mainly comprise three types: Firstly, the PCE consumption is simply increased, the method is high in cost and limited in effect; secondly, common micromolecular sacrificial agents (such as sodium sulfate and triethanolamine) are compounded, but the action of the sacrificial agents is not durable, and the continuous adsorption requirement of calcined clay is difficult to meet; Thirdly, a novel PCE is synthesized (such as adjusting the density of a side chain or carrying out quaternary ammonium salt modification), but the synthesis process of the quaternary ammonium salt modification PCE is complex, the stability in a high-alkalinity environment of a cement system is poor, the scheme for adjusting the density of the side chain essentially belongs to passive defense, and the effect is poor before calcining clay with strong adsorptivity. Therefore, developing a solution that can strongly block the adsorption sites without significantly increasing the cost and that is easy to industrialize has become an urgent need in the industry. Furthermore, while there are reports of using cationic polymers (such as poly (N, N-dimethylallylamine)) or quaternary ammonium salt modified PCEs to cope with clay adsorption in the prior art, these schemes have significant limitations in that 1) the effect of small molecule cationic sacrificial agents is not durable, 2) the adsorption strength and coverage efficiency of poly (N, N-dimethylallylamine) on clay are still insufficient to completely protect PCEs when used alone, and 3) the synthesis of quaternary ammonium salt modified PCEs is complex and may not be stable in high alkalinity environments. In particular, for calcined clay added as the main gelling component, the total adsorption amount and the duration thereof are far higher than those of clay accidentally mixed in the aggregate, resulting in rapid attenuation of the effect of the existing anti-mud technology. Therefore, developing a novel additive scheme with strong adsorption, lasting effect and good compatibility with a cement system to inhibit ineffective adsorption of calcined clay on the water reducer is a technical problem to be solved in the field. Disclosure of Invention Aiming at the technical problems, the application provides a composite additive solution based on a double synergistic mechanism. The application provides a composite additive for inhibiting ineffective adsorption of calcined clay to a water reducer, which comprises the following components: The composite additive comprises a component A and a component B, wherein the component A is a biscationic sacrificial agent, the biscationic sacrificial agent is prepared by reacting poly (N, N-dimethylallylamine) with tetrakis (hydroxymethyl) phosphonium sulfate in an aqueous solution at 60-80 ℃, the component B is a polycarboxylic acid water reducer, and the polycarboxylic acid water reducer is prepared by carrying out free radical copolymerization on a monomer mixture through the aqueous solution, and the monomer mixture comprises an unsaturated polyether macromonomer, an unsaturated carboxylic acid monomer and an unsaturated monomer containing a phosphoric acid group. The core design idea is as follows: 1. The first synergy was innovatively using a biscationic synergistic sacrificial agent (component a) made by reacting poly (N, N-dimethylallylamine) with tetrakis (hydroxymethyl) phosphonium sulfate. Poly (N, N-dimethylallylamine) provides a long-chain cation framework and high charge density, THPS is used as a cross-linking agent and a phosphorus cation source, a reaction product of the THPS has stronger positive electricity, a quaternary ammonium salt group and a phosphoric acid group on a molecular chain of the THPS can generate a double-cation synergistic adsorption effect, the combination of the quaternary ammonium