CN-122010452-A - Internal curing agent suitable for ultra-high performance concrete and preparation method thereof

Abstract

The invention belongs to the technical field of concrete additives, and particularly relates to an internal curing agent suitable for ultra-high performance concrete and a preparation method thereof, wherein the internal curing agent is prepared from, by weight, 3-5 parts of tapioca powder, 1-2 parts of porous analcite spheres, 1-2 parts of gamma-type nano alumina, 5-12 parts of anionic monomers, 55-100 parts of nonionic monomers, 0.2-0.5 part of an initiator, 0.2-0.5 part of a cross-linking agent and 100-300 parts of deionized water. The internal curing agent for concrete, which is prepared by the preparation method, is spherical negative-nonionic internal curing agent for concrete, has the water absorption rate of 80-100, has hydrophilic and alkali-resistant groups, has the particle size of 20-50 mu m, has small influence on the mechanical properties of the concrete, can effectively inhibit early shrinkage of the concrete, and further improves the volume stability of the concrete and reduces the cracking risk.

Inventors

• MING YANG
• LIU JIANZE
• LI LING
• SHAO SHIFENG
• HU CHENG
• XIANG WEIHENG
• LI QING
• ZHENG QUANXING
• ZHU XUEQIN

Assignees

• 桂林理工大学

Dates

Publication Date

20260512

Application Date

20251231

Claims (8)

1. 1. The internal curing agent suitable for the ultra-high performance concrete is characterized by being prepared from the following components in parts by weight: 3-5 parts of tapioca flour, 1-2 parts of porous analcite sphere, 1-2 parts of gamma-type nano alumina, 5-12 parts of anionic monomer, 55-100 parts of nonionic monomer, 0.2-0.5 part of initiator, 0.2-0.5 part of cross-linking agent and 100-300 parts of deionized water.
2. 2. The internal curing agent for ultra-high performance concrete according to claim 1, wherein said anionic monomer is one or more of sodium methallyl sulfonate and 2-acrylamido-2-methylpropanesulfonic acid.
3. 3. The internal curing agent for ultra-high performance concrete according to claim 1, wherein said nonionic monomer is one or more of acrylamide, methacrylamide, N-methylacrylamide and N, N-dimethylacrylamide.
4. 4. The internal curing agent for ultra-high performance concrete according to claim 1, wherein said initiator is one or more of potassium persulfate and ammonium persulfate.
5. 5. The internal curing agent for ultra-high performance concrete according to claim 1, wherein the particle size of the porous analcite sphere is 10-20 μm, the specific surface area is not less than 600m 2 /g, and the porosity is 50-60%.
6. 6. An internal curing agent for ultra-high performance concrete according to claim 1, wherein the particle size of the gamma-type nano-alumina is 150-300nm.
7. 7. An internal curing agent for ultra-high performance concrete as defined in claim 1, wherein said cross-linking agent is one of N, N' -methylenebisacrylamide, ethylene glycol dimethacrylate or ethylene glycol diglycidyl ether.
8. 8. A method for preparing an internal curing agent for ultra-high performance concrete according to any one of claims 1 to 7, comprising the steps of: (1) Respectively weighing 3-5 parts of tapioca powder, 1-2 parts of porous analcite spheres, 1-2 parts of gamma-type nano alumina, 0.2-0.5 part of initiator and 0.2-0.5 part of cross-linking agent, dissolving in 100-150 parts of deionized water, and fully stirring to obtain a mixed solution A; (2) Respectively weighing 5-12 parts of anionic monomers and 55-100 parts of nonionic monomers, dissolving in 100-150 parts of deionized water, and fully stirring to obtain a monomer solution B; (3) Dropwise adding the monomer solution B prepared in the step (2) into the mixed solution A prepared in the step (1) at 60-80 ℃ for reaction, wherein the dropwise adding time of the monomer solution B is controlled to be 1-2 hours, and the reaction time is 4-6 hours; (4) And (3) filtering and washing the copolymer prepared in the step (3), carrying out atomization drying for 2-4 hours at 220-250 ℃, then carrying out constant-temperature drying for 20-24 hours at 70-80 ℃ until the copolymer is completely dried, and carrying out atomization drying until the copolymer has a spherical structure with an average particle size of 20-50 mu m, thus obtaining the internal curing agent.

Description

Internal curing agent suitable for ultra-high performance concrete and preparation method thereof Technical Field The invention belongs to the technical field of concrete additives, and particularly relates to an internal curing agent suitable for ultra-high-performance concrete and a preparation method thereof. Background The super absorbent resin (UHSAP) is a novel polymer material and can absorb water with the dead weight of tens or hundreds of times. The ultra-high performance concrete has ultra-high durability and ultra-high strength, the compressive strength exceeds 120MPa, the ultra-high performance concrete is a novel cement-based material developed in recent years, the water-gel ratio is usually 0.14-0.20, and the self-shrinkage is large due to the low water-gel ratio, so that early cracks are easy to occur. The adoption of the internal curing agent is an effective way for solving the problem, but the existing research shows that the internal curing agent doped with the super absorbent resin can reduce the strength of the concrete while reducing the self-shrinkage of the ultra-high-performance concrete, and the development of a new internal curing agent without reducing the strength of the concrete is urgently needed. The internal curing agent material is added into the concrete in an internal mixing mode, has the functions of reducing shrinkage, inhibiting cracking, improving water retention and the like, ensures that the concrete has better pouring performance, realizes long-acting internal water retention curing, and obviously reduces the cracking risk of the concrete. At present, the commercial super absorbent resin is generally prepared and synthesized by adopting acrylic acid as a raw material, the water absorption rate of the product is too high, the liquid absorption rate is too high, excessive mixing water is easily absorbed in early stage when the product is used as an internal curing agent, the working performance of concrete is greatly reduced, the actual construction requirement cannot be met, and the application of the super absorbent resin in the field of construction is further limited, so that the internal curing agent of the concrete must have slower liquid absorption rate and lower water absorption rate. However, the existing internal curing agents mostly use porous lightweight aggregates such as kaolin, bentonite, and the like. As disclosed in CN201110195132.0, a preparation method of water-retaining, salt-resistant and alkali-resistant concrete internal curing agent is disclosed, which uses plant starch, inorganic powder with layered structure, anionic monomer, nonionic monomer and water as main raw materials, and under the action of initiator, cross-linking agent and a certain temperature, the 75-150 μm internal curing agent is prepared through dissolution, reaction, filtration, washing, drying and crushing, thus solving the problem of limited internal curing effect caused by poor salt-resistant and alkali-resistant properties of the traditional SAP, but after swelling, the particle size becomes at least 5 times of the original one, the pore diameter is bigger after water release, and larger pores are left in the concrete, thereby bringing adverse influence factors to the mechanical properties of the concrete. Therefore, how to provide an internal curing agent suitable for ultra-high performance concrete is a technical problem to be solved. Disclosure of Invention The invention aims to provide an internal curing agent suitable for ultra-high performance concrete and a preparation method thereof, so as to solve the problems in the background technology. In order to achieve the aim, the invention provides the technical scheme that the internal curing agent suitable for the ultra-high performance concrete is prepared from the following components in parts by weight: 3-5 parts of tapioca flour, 1-2 parts of porous analcite sphere, 1-2 parts of gamma-type nano alumina, 5-12 parts of anionic monomer, 55-100 parts of nonionic monomer, 0.2-0.5 part of initiator, 0.2-0.5 part of cross-linking agent and 100-300 parts of deionized water. Further, the anionic monomer is one or more of sodium methacrylate and 2-acrylamido-2-methylpropanesulfonic acid. Further, the nonionic monomer is one or more of acrylamide, methacrylamide, N-methylacrylamide and N, N-dimethylacrylamide. The acrylamide compound belongs to a nonionic monomer, has strong saline-alkali resistance and weaker water absorption capacity, but has higher water absorption rate than the acrylic compound, and improves the gel strength and strong alkali resistance of the synthetic resin by copolymerizing the acrylamide compound according to a certain proportion. The internal curing agent for concrete obtained by the preparation method is spherical negative-nonionic internal curing agent for concrete, has the water absorption rate of 80-100, has hydrophilic and alkali-resistant groups, has the particle size of 20-50 mu m, is placed in