High-fluidity self-compacting grouting dry-mixed mortar and preparation method thereof

Abstract

The application discloses a high-flow-state self-compacting grouting dry-mixed mortar and a preparation method thereof, and belongs to the technical field of building materials. The mortar comprises, in parts by weight, cementing material 350-450 parts, modified spherical steel slag sand microbeads 500-600 parts, water reducing agent 4-8 parts, plastic expansion agent 0.1-0.5 parts and defoaming agent 0.1-0.5 parts. The alkali-responsive ionized modified warm rubber is pre-anchored on the surface of the spherical steel slag sand through a chemical bond, the ball rolling effect during mixing is fully played, the anti-segregation effect during the standing period is fully played, and the automatic triggering under the alkali condition is realized. The application solves the problems that the flowability and the anti-segregation property of the existing grouting mortar are difficult to be considered, the anti-segregation agent is directly mixed to easily cause a large loss of the flowability, and the dispersion is uneven. The obtained mortar has an initial flowability of greater than or equal to 325 mm, a bleeding rate of zero and a 28d compressive strength of greater than or equal to 85 MPa.

Description

Technical Field

[0001] This invention relates to the field of building mortar materials technology, specifically to a high-fluidity self-compacting dry-mixed mortar and its preparation method. Background Technology

[0002] High-fluidity self-compacting grouting mortar is a key material for ensuring the integrity of prefabricated building structures and is widely used for secondary grouting of large equipment foundations and engineering reinforcement. High-fluidity self-compacting grouting mortar possesses extremely high fluidity, enabling it to fill dense, complex, and narrow grouting cavities under its own weight. Simultaneously, it must possess excellent anti-segregation capabilities to prevent fine aggregate settling and bleeding, ensuring stable volume and uniform strength of the hardened grout. While high fluidity allows for self-compacting filling, it often reduces anti-segregation properties, leading to easy settling and bleeding of fine aggregates. Conversely, increasing anti-segregation properties significantly reduces fluidity, making it difficult to meet the requirements of self-compacting grouting. In particular, if anti-segregation agents are added on-site, they are prone to uneven dispersion and localized clumping, making it impossible to construct a uniform and effective anti-segregation mortar system. Therefore, there is an urgent need to develop a dry-mixed grout that can maintain ultra-high fluidity during the mixing and grouting stages to achieve high-fluidity self-compacting filling, and has excellent anti-segregation performance after grouting, so as to fundamentally solve the problem of the difficulty in achieving both fluidity and anti-segregation. Summary of the Invention

[0003] To address the above problems, this invention provides a high-fluidity self-compacting dry-mixed grout and its preparation method, which solves the problems of difficulty in simultaneously achieving fluidity and anti-segregation properties in grouting mortar, and the tendency for direct incorporation of anti-segregation agents to lead to significant loss of fluidity or uneven dispersion.

[0004] To achieve the above objectives, the technical solution adopted by the present invention is as follows: A high-fluidity self-compacting dry-mixed grouting mortar comprises the following raw materials by weight: 350-450 parts of cementitious material; 500-600 parts of modified spherical steel slag microspheres; 4-8 parts of water-reducing agent; 0.1~0.5 parts of plastic expander; 0.1 to 0.5 parts of defoamer.

[0005] Preferably, the cementitious material comprises cement and fly ash microspheres, wherein the mass ratio of cement to fly ash microspheres is (1~3):1.

[0006] Preferably, the cement is P·II 52.5 silicate cement, and the fly ash microspheres have a sphericity ≥0.90.

[0007] Preferably, the plasticizing agent is azodicarbonamide or benzenesulfonyl hydrazine, and the defoamer powder is a polyether-modified organosilicon powder defoamer.

[0008] Preferably, the water-reducing agent is a powdered polycarboxylate high-performance water-reducing agent with a solid content ≥95%.

[0009] Preferably, the method for preparing the modified spherical steel slag sand is as follows: (1) Soak the spherical steel slag sand microspheres in dilute hydrochloric acid, clean and dry them, then immerse them in an ethanol aqueous solution of silane coupling agent KH-570, stir in a water bath to carry out the reaction, filter out the solid, dry and solidify to obtain coupling agent pretreated microspheres. (2) Prepare an aqueous solution of the anti-segregation agent, add hydrogen peroxide for oxidative degradation, and add acrylic monomer and ammonium persulfate initiator under nitrogen protection to react and obtain an ionized modified anti-segregation agent solution; (3) The microspheres pretreated with coupling agent in step (1) are mixed with the solution of ionized modified anti-segregation agent in step (2), and the crosslinking agent N,N'-methylenebisacrylamide is added at the same time. The mixture is then fluidized and dried to form a film, thus obtaining modified spherical steel slag sand microspheres.

[0010] Preferably, the spherical steel slag microspheres have a particle size of 0.3mm~2.36mm and a sphericity ≥0.85.

[0011] Preferably, the antisegregation agent is glutaraldehyde.

[0012] Preferably, in step (2), the anti-segregation agent undergoes oxidative degradation, reducing its molecular weight to 1 / 3 to 1 / 2 of its original molecular weight.

[0013] The second objective of this invention is to provide a method for preparing any of the above-mentioned high-fluidity self-compacting dry-mixed mortars, comprising the following preparation steps: (1) Weigh the cementitious material, modified spherical steel slag sand microspheres, water-reducing agent, plastic expansion agent and defoamer according to the proportion, put them into the dry powder mixer and mix them until uniform to obtain the dry-mixed mortar finished product; (2) Add clean water at a water-to-material ratio of 0.25~0.3, stir evenly, and after standing and maturing, stir evenly again to make high-flow self-compacting grouting mortar that can be used for gravity grouting or pressure grouting.

[0014] The working mechanism of this invention is as follows: During the dry mixing and storage stage, the polymer film shell on the surface of the modified spherical steel slag sand microspheres is in a dry and dense state, with stable chemical properties, and does not absorb moisture or stick together.

[0015] In the initial stage of water mixing, water molecules preferentially wet the cementitious materials and additives. The polymer film on the surface of the microspheres remains intact for a short time, and the rolling friction and ball effect between the spherical particles are fully utilized, enabling the mortar to achieve high fluidity with low water consumption and realize self-compacting grouting.

[0016] After grouting is completed, as the cement hydrates, the alkalinity of the mortar's liquid phase continues to increase, and the OH- - Ions begin to gradually attack the cross-linking bonds between the coupling agent and the polymer, as well as the Si-O-Si bonds between the coupling agent and the steel slag surface, causing the membrane shell to slowly swell and dissolve from the surface. The ionized modified styrene macromolecules continuously enter the slurry pore solution in a slow-release manner. The released styrene macromolecular chains carry a large number of carboxyl anions introduced by acrylic acid copolymerization. These groups react with the large amount of Ca produced during cement hydration. 2+ Complexation and bridging occur, forming "-COO" - ···Ca 2+ ··· - OOC- ion crosslinking nodes, with multiple macromolecular chains interconnected, form a relatively continuous three-dimensional crosslinked structure in the interstitial solution of the slurry. This significantly increases the yield stress of the slurry and effectively inhibits the settling of fine aggregates and the exudation of water in the mortar.

[0017] The beneficial effects of this invention are as follows: This application pre-anchors the anti-segregation agent to the surface of spherical steel slag sand microspheres through chemical bonds, forming a slow-release functional aggregate. Specifically, during the mixing period, the membrane shell of the spherical steel slag sand microspheres remains intact, and the mortar has ultra-high fluidity under the ball effect. During the settling period, the alkaline environment formed by cement hydration allows the anti-segregation agent to be slowly released into the mortar system, thereby improving the anti-segregation properties of the mortar.

[0018] This application utilizes the residual free calcium oxide in the steel slag sand microspheres as an auxiliary alkali source to form a dual alkali source with cement hydration, creating alkaline conditions. Specifically, after the cement hydration alkali solution penetrates to the interface between the membrane shell and the steel slag core, the free calcium oxide inside the steel slag further hydrates to generate calcium hydroxide. This not only continuously replenishes the alkalinity required for membrane hydrolysis, but its solid phase volume expansion effect can also accelerate the peeling of the outer polymer membrane and the release of the anti-segregation agent, forming a synergistic effect of alkali activation and slow release.

[0019] (3) This application introduces a large number of carboxyl anions through the ionization modification of the anti-segregation agent, thereby increasing the complexation and cross-linking ability of calcium ions in the slurry. Specifically, during the settling stage, the modified gluten macromolecular chains carrying -COO are slowly released into the slurry interstices. - Groups and Ca dissolved from cement hydration 2+ It forms ion-bridged nodes, and multiple macromolecular chains are interconnected to rapidly build a cross-linked network, which greatly improves the yield stress of the slurry, effectively inhibits the settling and bleeding of fine aggregates, and the reversible nature of physical cross-linking does not affect the continuous hydration of cement. Detailed Implementation

[0020] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be described in detail below. The description in this part is only exemplary and explanatory, and should not be used to limit the scope of protection of the present invention in any way.

[0021] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, specific embodiments of the present invention are described in detail below. Many specific details are set forth in the following description to provide a thorough understanding of the present invention. However, the present invention can be practiced in many other ways different from those described herein, and those skilled in the art can make similar modifications without departing from the spirit of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0022] Example 1: (1) Preparation of modified spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0023] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0024] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0025] The coupling agent-pretreated microspheres were placed in a fluidized bed equipped with a spraying device. An ionized modified anti-segregation agent solution was sprayed on, with the amount calculated as 0.10% of the dry weight of the slag binder to the mass of the microspheres. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, was sprayed on, accounting for 6% of the dry weight of the slag binder. After spraying, the microspheres were fluidized and dried at 60°C for 50 minutes, yielding the modified spherical steel slag sand microspheres.

[0026] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of modified spherical steel slag sand microspheres, 6 parts of polycarboxylate superplasticizer powder (96% solid content), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0027] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0028] Example 2: (1) Preparation of modified spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0029] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0030] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0031] The coupling agent-pretreated microspheres were placed in a fluidized bed equipped with a spraying device. An ionized modified anti-segregation agent solution was sprayed on, with the amount calculated as 0.10% of the dry weight of the slag binder to the mass of the microspheres. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, was sprayed on, accounting for 6% of the dry weight of the slag binder. After spraying, the microspheres were fluidized and dried at 60°C for 50 minutes, yielding the modified spherical steel slag sand microspheres.

[0032] (2) Preparation of dry-mixed mortar: 210 parts of P·II 52.5 silicate cement, 140 parts of fly ash microspheres (sphericity 0.92) (cement:fly ash microsphere mass ratio 1.5:1), 580 parts of modified spherical steel slag sand microspheres, 7 parts of polycarboxylate superplasticizer powder (solid content 96%), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0033] (3) Construction and testing: Add water at a water-to-material ratio of 0.26, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0034] Example 3: (1) Preparation of modified spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0035] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0036] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0037] Pretreated microspheres with coupling agent were placed in a fluidized bed equipped with a spraying device. An ionized modified anti-segregation agent solution was sprayed on, with the amount calculated as 0.15% of the dry weight of the slag binder to the mass of the microspheres. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, was sprayed on, accounting for 6% of the dry weight of the slag binder. After spraying, the microspheres were fluidized at 60℃ for 50 minutes, and the modified spherical steel slag sand microspheres were obtained.

[0038] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of modified spherical steel slag sand microspheres, 6 parts of polycarboxylate superplasticizer powder (96% solid content), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0039] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0040] Example 4: (1) Preparation of modified spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0041] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0042] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0043] The coupling agent-pretreated microspheres were placed in a fluidized bed equipped with a spraying device. An ionized modified anti-segregation agent solution was sprayed on, with the amount calculated as 0.10% of the dry weight of the slag binder to the mass of the microspheres. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, was sprayed on, accounting for 6% of the dry weight of the slag binder. After spraying, the microspheres were fluidized and dried at 60°C for 50 minutes, yielding the modified spherical steel slag sand microspheres.

[0044] (2) Preparation of dry-mixed mortar: 337.5 parts of P·II 52.5 silicate cement, 112.5 parts of fly ash microspheres (sphericity 0.92) (cement:fly ash microspheres mass ratio 3:1), 500 parts of modified spherical steel slag sand microspheres, 5 parts of polycarboxylate superplasticizer powder (solid content 96%), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0045] (3) Construction and testing: Add water at a water-to-material ratio of 0.25, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0046] Example 5: (1) Preparation of modified spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0047] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0048] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0049] The coupling agent-pretreated microspheres were placed in a fluidized bed equipped with a spraying device. An ionized modified anti-segregation agent solution was sprayed on, with the amount calculated as 0.10% of the dry weight of the slag binder to the mass of the microspheres. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, was sprayed on, accounting for 6% of the dry weight of the slag binder. After spraying, the microspheres were fluidized and dried at 60°C for 50 minutes, yielding the modified spherical steel slag sand microspheres.

[0050] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of modified spherical steel slag sand microspheres, 4 parts of polycarboxylate superplasticizer powder (96% solid content), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0051] (3) Construction and testing: Add water at a water-to-material ratio of 0.28, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0052] Comparative Example 1: (1) Preparation of spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C to obtain ordinary spherical steel slag sand microspheres without any surface chemical modification, for later use.

[0053] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of the above-mentioned ordinary spherical steel slag sand microspheres, 6 parts of polycarboxylate superplasticizer powder (96% solid content), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Additionally, 0.10% of the dry weight of the PVC-U adhesive is directly added. All components are mixed in a dry powder mixer for 20 minutes until homogeneous, then sealed and packaged.

[0054] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0055] Comparative Example 2: (1) Preparation of spherical steel slag sand microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C to obtain ordinary spherical steel slag sand microspheres without any surface chemical modification, for later use.

[0056] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of the above-mentioned ordinary spherical steel slag sand microspheres, 6 parts of polycarboxylate superplasticizer powder (96% solid content), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. No anti-segregation agents are added. All components are added to a dry powder mixer and mixed for 20 minutes until homogeneous. The mixture is then sealed and packaged.

[0057] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0058] Comparative Example 3: (1) Preparation of modified spherical steel slag microspheres: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0059] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0060] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0061] The coupling agent-pretreated microspheres were placed in a fluidized bed equipped with a spraying device. An ionized modified anti-segregation agent solution was sprayed on, with the amount calculated as 0.10% of the dry weight of the slag binder to the mass of the microspheres. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, was sprayed on, accounting for 6% of the dry weight of the slag binder. After spraying, the microspheres were fluidized and dried at 60°C for 50 minutes, yielding the modified spherical steel slag sand microspheres.

[0062] (2) Preparation of dry-mixed mortar: 400 parts of finely ground limestone powder (inert filler), 550 parts of the above-mentioned modified spherical steel slag sand microspheres, 6 parts of polycarboxylate superplasticizer powder (96% solid content), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether-modified silicone defoamer powder. The inert filler completely replaces cement and fly ash microspheres. The system contains no hydraulic cementitious materials, and after adding water, there is no cement hydration alkali source; the only alkalinity relies on the weak alkalinity of residual free calcium oxide in the modified sand. All components are added to a dry powder mixer and mixed for 20 minutes until homogeneous, then sealed and packaged.

[0063] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0064] Comparative Example 4: (1) Preparation of pre-swollen steel slag sand microspheres Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0065] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0066] An 8% aqueous solution of the anti-segregation agent, sorbitol, was prepared. 4% (by weight of the sorbitol) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade the sorbitol. The intrinsic viscosity was measured to have decreased to 38% of its original value. Nitrogen gas was then introduced to remove oxygen. 15% (by weight of the sorbitol) of acrylic monomer and 0.3% (by weight of ammonium persulfate) were added, and the mixture was reacted at 65°C for 3 hours under nitrogen protection to obtain an ionized modified anti-segregation agent solution.

[0067] The coupling agent-pretreated microspheres were immersed in an ionized modified anti-segregation agent solution at a dosage of 0.10% of the dry weight of the sorbent polymer to the mass of the microspheres, while N,N'-methylenebisacrylamide, a crosslinking agent, was added at 6% of the dry weight of the sorbent polymer. After uniform immersion, the microspheres were removed and allowed to air dry naturally at room temperature (without fluidized bed drying). The resulting microspheres did not form a dense film on their surface and remained in a pre-swollen state.

[0068] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of the above-mentioned pre-expanded steel slag sand microspheres, 6 parts of polycarboxylate superplasticizer powder (solid content 96%), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified silicone defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0069] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0070] Comparative Example 5: (1) Preparation of steel slag sand microspheres coated with unionized modified warm wheel adhesive: Spherical steel slag sand produced by the plate-splashing water quenching process was crushed and screened to obtain particle sizes ranging from 0.3 mm to 2.36 mm, with a sphericity of 0.88. The microspheres were then immersed in 5% dilute hydrochloric acid for 30 minutes, washed with deionized water, and dried at 105°C.

[0071] A 1.8% KH-570 coupling agent solution was prepared using an ethanol-water mixture with a volume ratio of 9:1. The pH was adjusted to 4.5 with acetic acid, and the solution was stirred and hydrolyzed for 30 min. The pretreated microbeads were then added to the coupling agent solution and reacted in a 50°C water bath with stirring for 2 h. The solid was filtered off and dried and cured in an oven at 110°C for 1.5 h to obtain the coupling agent pretreated microbeads.

[0072] An 8% aqueous solution of the anti-segregation agent, acetone, was prepared. 4% (by mass) of a 30% hydrogen peroxide solution was added, and the solution was stirred at 40°C for 2.5 hours to degrade it. The intrinsic viscosity was measured to have decreased to 38% of its original value. This acetone only underwent oxidative degradation and did not undergo subsequent acrylic copolymerization ionization modification (i.e., no carboxyl anions were introduced, affecting Ca2+). 2+ (No complexation or cross-linking).

[0073] The coupling agent-pretreated microspheres were placed in a fluidized bed equipped with a spraying device. A solution of only oxidatively degraded urethane was sprayed onto the microspheres at a rate of 0.10% of the dry weight of the urethane. Simultaneously, an aqueous solution of N,N'-methylenebisacrylamide, a crosslinking agent, at 6% of the dry weight of the urethane, was sprayed in. After spraying, the microspheres were fluidized at 60°C for 50 minutes, and the resulting material was steel slag sand microspheres coated with unionized urethane.

[0074] (2) Preparation of dry-mixed mortar: 280 parts of P·II 52.5 silicate cement, 120 parts of fly ash microspheres (sphericity 0.92), 550 parts of steel slag sand microspheres coated with the above-mentioned unionized modified warm wheel rubber, 6 parts of polycarboxylate superplasticizer powder (solid content 96%), 0.3 parts of azodicarbonamide plastic expansion agent, and 0.15 parts of polyether modified organosilicon defoamer powder. Mix in a dry powder mixer for 20 minutes until homogeneous, then seal and package.

[0075] (3) Construction and testing: Add water at a water-to-material ratio of 0.27, stir at low speed for 3 minutes, let stand and mature for 2 minutes, then stir again until homogeneous. Test according to GB / T50448-2015.

[0076] Performance testing: Initial truncated cone flowability: According to Appendix A of GB / T 50448-2015 "Technical Specification for Application of Cement-based Grouting Materials", the truncated cone flowability (mm) was measured immediately after adding water, stirring, and allowing to stand for curing.

[0077] 30-minute truncated cone flowability: The truncated cone flowability was measured again at 30 minutes after adding water and stirring, which characterizes the ability of the flowability to be maintained over time.

[0078] Bleeding rate: According to the method specified in GB / T 50448-2015, the freshly mixed mortar is poured into a specified container, left to stand for 3 hours, the surface water is extracted and weighed, and the bleeding rate (%) is calculated.

[0079] Vertical expansion rate (3h / 24h): According to GB / T 50448-2015, the vertical expansion rate (%) of mortar in the plastic stage (3h) and the initial hardening stage (24h) is measured by dial gauge method.

[0080] Compressive strength (1d, 28d): Mold 40mm×40mm×160mm prism specimens, cure to the specified age according to standard, and test the compressive strength (MPa).

[0081] Table 1 shows the performance test data for the example.

[0082] Table 2 shows the performance test data for the comparative examples.

[0083] From Table 1 and Table 2, we can obtain: (1) The initial truncated cone flowability of the mortars in Examples 1 to 5 was all above 325 mm, the flowability retention rate after 30 minutes was all above 90%, and the bleeding rate was all zero. Compared with the initial flowability of 350 mm for the mortar in Example 1, the initial flowability of Comparative Example 2 was 345 mm, which is similar to the initial flowability of the mortar in Example 2. This indicates that the dense polymer membrane shell of this application effectively isolated the contact between the anti-segregation agent and the slurry in the early stage of mixing, so that the ball effect of the spherical steel slag sand microspheres could be fully released. At the same time, the bleeding rate of Example 1 was zero, while the bleeding rate of Comparative Example 2 was as high as 2.8%, indicating that the membrane shell of the mortar successfully released the ionized modified warm wheel colloid in the alkaline environment of cement hydration during the static stage, and reacted with Ca 2+ A three-dimensional anti-segregation network structure was constructed through complexation. The initial fluidity of Comparative Example 1 dropped sharply to 285 mm, which was a significant decrease compared to Example 1. This confirms that by pre-anchoring the anti-segregation agent to the surface of spherical steel slag sand microspheres through chemical bonds, the high fluidity of the mortar in the early stage and the high anti-segregation performance in the later stage can be achieved simultaneously and coordinated.

[0084] (2) Comparative Example 3 completely replaced the cementitious material with inert limestone powder. The system lacked an alkaline source for cement hydration. Although the initial fluidity reached 331 mm, the bleeding rate was 1.5%, and the 28-day strength was only about 8 MPa. Compared with the zero bleeding rate and 90 MPa strength of Example 1, both examples demonstrate that the high-alkaline environment provided by cement hydration is a necessary condition for triggering the hydrolysis of the polymer membrane and the release of the anti-segregation agent. The lack of an alkaline source renders the slow-release mechanism ineffective. Comparative Example 5, coated with unmodified ordinary styrene, had an initial fluidity comparable to Example 1, but a bleeding rate as high as 2.4%, close to the 2.8% bleeding rate of Comparative Example 2 without an anti-segregation mechanism. This indicates that even if the polymer membrane can release slowly under alkaline conditions, if the styrene molecular chain lacks the carboxyl anion introduced by acrylic acid copolymerization, it cannot react with Ca2+. 2+ Effective complexation and cross-linking cannot occur, and a three-dimensional network cannot be formed, resulting in insufficient anti-segregation performance.

[0085] (3) The dense polymer film shell of this application ensures the ball effect and initial high fluidity during mixing, the alkaline environment of cement hydration provides slow-release triggering conditions, and the ionization modification of the anti-segregation agent and Ca 2+ Complexation and cross-linking constitute the network structure, and all three are indispensable. The examples consistently achieved excellent comprehensive performance with an initial flowability ≥325 mm, zero bleeding rate, and 28-day compressive strength ≥85 MPa across a wide range of formulation ratios. It should be noted that, in this document, the terms “comprising,” “including,” or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0086] This article uses specific examples to illustrate the principles and implementation methods of the present invention. The above examples are only for the purpose of helping to understand the method and core ideas of the present invention. The above descriptions are only preferred embodiments of the present invention. It should be noted that due to the limitations of textual expression, while there are objectively infinite specific structures, those skilled in the art can make several improvements, modifications, or changes without departing from the principles of the present invention, and can also combine the above technical features in an appropriate manner. These improvements, modifications, changes, or combinations, or the direct application of the inventive concept and technical solution to other situations without modification, should all be considered within the scope of protection of the present invention.

Claims

1. A high-fluidity self-compacting dry-mixed grout, characterized in that, The following ingredients are included by weight: 350-450 parts of cementitious material; 500-600 parts of modified spherical steel slag microspheres; 4-8 parts of water-reducing agent; 0.1~0.5 parts of plastic expander; 0.1 to 0.5 parts of defoamer.

2. The mortar according to claim 1, characterized in that, The cementitious material includes cement and fly ash microspheres, and the mass ratio of cement to fly ash microspheres is (1~3):

1.

3. The mortar according to claim 2, characterized in that, The cement is P·II 52.5 silicate cement, and the fly ash microspheres have a sphericity ≥0.

90.

4. The mortar according to claim 1, characterized in that, The plasticizing agent is azodicarbonamide or benzenesulfonyl hydrazine, and the defoamer powder is a polyether-modified organosilicon powder defoamer.

5. The mortar according to claim 1, characterized in that, The water-reducing agent is a powdered polycarboxylate high-performance water-reducing agent with a solid content ≥95%.

6. The mortar according to claim 1, characterized in that, The method for preparing the modified spherical steel slag sand is as follows: (1) Soak the spherical steel slag sand microspheres in dilute hydrochloric acid, clean and dry them, then immerse them in an ethanol aqueous solution of silane coupling agent KH-570, stir in a water bath to carry out the reaction, filter out the solid, dry and solidify to obtain coupling agent pretreated microspheres. (2) Prepare an aqueous solution of the anti-segregation agent, add hydrogen peroxide for oxidative degradation, and add acrylic monomer and ammonium persulfate initiator under nitrogen protection to react and obtain an ionized modified anti-segregation agent solution; (3) The microspheres pretreated with coupling agent in step (1) are mixed with the solution of ionized modified anti-segregation agent in step (2), and the crosslinking agent N,N'-methylenebisacrylamide is added at the same time. The mixture is then fluidized and dried to form a film, thus obtaining modified spherical steel slag sand microspheres.

7. The mortar according to claim 6, characterized in that, The spherical steel slag sand microspheres have a particle size of 0.3mm~2.36mm and a sphericity ≥0.

85.

8. The mortar according to claim 6, characterized in that, The anti-segregation agent is gluten gel.

9. The mortar according to claim 6, characterized in that, In step (2), the anti-segregation agent undergoes oxidative degradation, reducing its molecular weight to 1 / 3 to 1 / 2 of its original molecular weight.

10. The method for preparing high-fluidity self-compacting dry-mixed grouting mortar according to any one of claims 1 to 9, characterized in that, The preparation steps include the following: (1) Weigh the cementitious material, modified spherical steel slag sand microspheres, water-reducing agent, plastic expansion agent and defoamer according to the proportion, put them into the dry powder mixer and mix them until uniform to obtain the dry-mixed mortar finished product; (2) Add clean water at a water-to-material ratio of 0.25~0.3, stir evenly, and after standing and maturing, stir evenly again to make high-flow self-compacting grouting mortar that can be used for gravity grouting or pressure grouting.

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