Superfine powder composite high-strength non-shrinkage grouting material

Abstract

The present application relates to the technical field of building materials, in particular to a kind of ultrafine powder composite high-strength non-shrinkage grouting material, which is composed of dry powder and mixed water, the dry powder includes main material, reinforcing material and functional additional material; the present application combines four typical solid wastes, i.e., construction waste regeneration powder, waste glass powder, waste plastics and agricultural straw waste, through specific physical and chemical treatment and ultrafine co-milling process, and granulates them into porous functional particles with specific functions; the design not only greatly improves the problem of low utilization rate of single solid waste, but also changes it from simple filler to active component capable of actively improving the microstructure of slurry and adjusting moisture distribution through functional design; this significantly reduces the dependence of grouting material on natural sand and high-performance mineral admixture, conforms to the development direction of green building materials, reduces the cost of raw materials, and realizes the unity of environmental and economic benefits.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to an ultrafine powder composite high-strength non-shrink grout. Background Technology

[0002] High-strength, non-shrink grout is a key material widely used in secondary grouting of equipment foundations, steel structure anchoring, and structural repair and reinforcement. Traditional grouts rely heavily on silicate cement, graded quartz sand, and various chemical admixtures (such as expanding agents and water-reducing agents) to ensure their core properties of high fluidity, early strength, high strength, and micro-expansion without shrinkage. In recent years, to improve economic efficiency and environmental friendliness, some research has begun to explore the introduction of industrial or construction solid waste into grout systems. High-strength, non-shrink grout is a key material in modern civil engineering for structural reinforcement, equipment foundation anchoring, and prefabricated building connections. Its core performance requirements include high fluidity, early strength, high strength, micro-expansion without shrinkage, and excellent durability. Traditional formulations typically use high-grade silicate cement, high-quality quartz sand, or manufactured sand as the main ingredients, and rely on chemical admixtures such as expanding agents, high-efficiency water-reducing agents, and early-strength agents to achieve the above properties.

[0003] For example, application number CN201710141371.5, with an authorization announcement date of 20190712, discloses a high-strength, non-shrink grouting material with high fluidity and its preparation method. The grouting material is composed of cement, mineral admixtures, dolomite composite powder, composite expansive agent, aggregate, polycarboxylate superplasticizer, and synergistic additives. The mass fractions of each component are: cement 30%-45%, mineral admixtures 5%-20%, dolomite composite powder 3%-10%, composite expansive agent 2%-8%, aggregate 40%-55%, polycarboxylate superplasticizer 0.2%-1.0%, and synergistic additives 0.2%-1.5%. This invention improves fluidity and strength through the close packing technology of powder system and aggregate; it introduces synergistic additives to regulate moisture distribution through the thickening and water absorption and release effects of composite anti-segregation agent, solving the problems of segregation, bleeding, and water sensitivity of large-flow grout; and it introduces plastic expansion agent, composite expansion agent, etc. to adjust the expansion performance at different stages, solving the shrinkage and settlement problems of grout.

[0004] For example, a high-strength non-shrink grouting material and its production method, with application number CN201710588849.9 and publication date 20170919, is characterized by comprising the following raw materials in parts by weight: 50-70 parts cement, 55-75 parts fine aggregate, 2-5 parts high-efficiency water-reducing agent, 0.5-2 parts early-strength agent, 0.1-0.5 parts expanding agent, 0.1-0.5 parts hydroxypropyl starch ether, 0.05-0.1 parts composite retarder, 0.1-0.5 parts water-retaining agent, and 0.05-0.1 parts defoamer; wherein the fine aggregate is quartz sand with a particle size of 20-80 mesh, of which 20-30 mesh accounts for 25%, 31-50 mesh accounts for 50%, and 51-80 mesh accounts for 25%. The high-strength, non-shrink grouting material of this invention is low in cost and easy to construct. The grouting material has high fluidity, high strength, no shrinkage, slight expansion, zero bleeding, no cracking, and no strength reduction. It has excellent high-strength construction performance and can meet the construction purpose of rapid construction and rapid use.

[0005] However, traditional or existing high-strength non-shrink grouting technologies still have several limitations and challenges, mainly reflected in: First, the reliance on high-performance natural raw materials remains high, which not only leads to high costs but also falls short of the industrial orientation of comprehensive resource utilization and the development of green building materials. Secondly, although some studies have attempted to introduce solid waste, they are usually limited in type and utilization rate. They have failed to systematically design and synergistically combine various solid wastes with different physicochemical properties to fully realize their potential in improving microstructure and endowing special functions. Thirdly, in terms of precise performance control, existing technologies mostly rely on the physical mixing of conventional expansion agents and admixtures. The timing and rate of expansion sources and their matching with the strength development of the slurry may not be precise enough. Especially in high-strength systems with extremely low water-cement ratios, it is difficult to perfectly balance the performance requirements of ultra-high early strength, ultra-high final strength and no shrinkage throughout the entire process under complex service conditions. There is a risk of later shrinkage or the hidden danger of strength reduction due to improper expansion. Fourth, in terms of controlling the internal microstructure of materials and improving long-term durability, the methods are relatively traditional. There is a lack of design to actively introduce beneficial and controllable pores to buffer stress and optimize pore structure. The ability to control the initiation and expansion of internal micro-defects needs to be further strengthened, which poses a potential impact on crack resistance, impermeability and long-term durability.

[0006] In view of this, there is an urgent need to design an ultrafine powder composite high-strength non-shrink grout to solve the above problems. Summary of the Invention

[0007] The purpose of this invention is to provide an ultrafine powder composite high-strength non-shrink grout to overcome the above-mentioned shortcomings in the prior art.

[0008] To achieve the above objectives, the present invention provides the following technical solution: A high-strength, non-shrink composite grouting material made of ultrafine powder is composed of dry powder and mixing water. The dry powder includes a main material, reinforcing materials, and functional additives. The amount of mixing water is controlled so that the final water-cement ratio of the grout is between 0.12 and 0.20; The main material includes: A composite cementitious material made by mixing silicate cement and sulfoaluminate cement in a mass ratio of (7-9):(1-3); It should be noted that: In the composite cementitious material: The silicate cement is grade 52.5 or higher silicate cement; The sulfoaluminate cement is grade 42.5 rapid-hardening sulfoaluminate cement; Continuously graded fine aggregate with a particle size of 0.15-2.5mm; It should be noted that: The continuously graded fine aggregate is composed of refined quartz sand and waste glass fine sand that has been washed, impurity removed, and magnetically separated at a mass ratio of (6-8):(2-4). The fine aggregate has an overall mud content of ≤0.5% and a SiO2 content of ≥95%; The reinforcing material is a porous functional particle made from recycled micro powder of construction waste, waste glass micro powder, surface-modified plastic micro powder, and anti-corrosion treated straw micro powder. It should be noted that: The steps for fabricating the porous functional particles are as follows: The mixture is made of recycled micro powder from construction waste, waste glass micro powder, surface-modified plastic micro powder and anti-corrosion treated straw micro powder in a mass ratio of (50-60):(25-35):(5-10):(5-10), and 1%-3% of nano SiO2 is added to the mixture. Ultrafine co-grinding to a specific surface area ≥400 m² 2 / kg, and then granulated to form matrix particles, the matrix particles are surface treated and coated with a cement-based active coating; The porous functional particles have a particle size of 0.5-2.0 mm, a porosity of 30%-40%, and a 24-hour water absorption rate of 15%-25%. The surface-modified plastic micro powder is prepared by crushing waste PET or PP plastic, followed by alkaline washing and surface hydrophilic modification with silane coupling agent. The anti-corrosion treated straw powder is obtained by crushing rice straw and then treating it with alkaline solution and organosilicon preservatives for preservation and fiber dissociation. The functional additives include polycarboxylate superplasticizers, composite expanding agents, early strength agents, water-retaining agents, defoamers, and microcapsule foaming agents that release gas in a controlled manner upon contact with water; the composite expanding agent is a compound of calcium sulfoaluminate expanding agents and plastic expanding agents; It should be noted that: The water-reactive microcapsule foaming agent has a core material composed of a complex of sodium bicarbonate and citric acid in a mass ratio of 1:(1-1.2). The coating material for the water-reactive microcapsule foaming agent is water-soluble starch, and the coating layer thickness is 1-20 μm. The microcapsule foaming agent releases bubbles with a diameter ≤100 μm upon contact with water; In the aforementioned functional additive materials: The water reduction rate of the polycarboxylate superplasticizer is ≥25%; The composite expanding agent is composed of calcium sulfoaluminate expanding agent and plastic expanding agent in a mass ratio of (8-12):1; The early-strength agent is calcium formate; In another embodiment of the present invention, the dosage of each functional additive component, based on a percentage of the total weight of the dry powder, is as follows: Polycarboxylate superplasticizer 0.5%-1.2%; Composite expanding agent 1.5%-3.5%; Early-strength agent: 0.5%-1.5%; Water-retaining agent 0.05%-0.15%; Defoamer 0.05%-0.15%; The microcapsule foaming agent is 0.1%-0.5%.

[0009] In another embodiment of the present invention, the composition, based on the total weight percentage of the dry powder, includes: The composite cementitious material comprises 25%-35%; The continuously graded fine aggregate comprises 30%-45%; The porous functional particles comprise 15%-30%; The functional additives comprise 2.7%-6.8%; The balance is unavoidable trace impurities.

[0010] In another embodiment of the present invention, the grouting material meets the following performance indicators: Initial flowability ≥300 mm, flowability retention value ≥260 mm after 30 min; 1-day compressive strength ≥ 30 MPa, 28-day compressive strength ≥ 80 MPa; The vertical free expansion rate over 24 hours is 0.02%-0.10%; The water exudation rate is ≤1.0%.

[0011] In the above technical solution, the ultrafine powder composite high-strength non-shrink grouting material provided by the present invention has the following beneficial effects: (1) This invention combines four typical solid wastes, namely, recycled micro powder from construction waste, waste glass micro powder, waste plastics and agricultural straw waste, through specific physicochemical treatment and ultrafine co-grinding process, and granulates them into porous functional particles with specific functions. This design not only greatly improves the problem of low utilization rate of single solid waste, but also transforms it from a simple filler into an active component that can actively improve the microstructure of slurry and regulate the distribution of moisture through functional design. This significantly reduces the dependence of grouting material on natural sand and gravel and high-performance mineral admixtures, which is in line with the development direction of green building materials. At the same time, it reduces the cost of raw materials and achieves the unity of environmental protection and economic benefits.

[0012] (2) The present invention innovatively adopts a dual expansion source composed of a composite expansion agent and a controllable gas-release microcapsule foaming agent. The composite expansion agent provides multi-stage chemical and plastic expansion covering the early and middle stages, while the microcapsule foaming agent achieves controllable delay of gas release timing and rate through precise design of its coating thickness. This design enables the expansion effect to be precisely matched with the key stages of the slurry from plastic state to strength formation and development, thereby effectively compensating for various shrinkages generated by cement-based materials at different stages. This synergistic mechanism fundamentally solves the problem of volume shrinkage that often accompanies the pursuit of ultra-high strength, and avoids strength loss or later shrinkage risk caused by improper expansion.

[0013] (3) By introducing porous functional particles rich in pores and controllable microbubbles, the present invention actively constructs a dispersed and uniform microporous system inside the material. These pores can not only play an "internal curing" role in the hardening process, continuously supplying water to promote the full hydration of the cementitious material and reduce self-shrinkage, but also effectively buffer internal stress, refine and optimize the overall pore structure of the slurry. This active intervention in the microstructure enables the material to obtain ultra-high strength while significantly enhancing its crack resistance, impermeability and ability to resist external erosion, thereby greatly improving the long-term service performance and durability of the material in complex environments.

[0014] (4) Through careful design, this invention enables deep synergy among the composite cementitious system, functional aggregates, porous particles and various functional admixtures. The extremely low water-cement ratio and high-efficiency water-reducing agent ensure the basic fluidity and strength. The composite cementitious system and early strength component ensure rapid strength development. The functional particles and expansion system work together to ensure dimensional stability throughout the process. Other functional admixtures further optimize the construction performance. Each component performs its own function and promotes each other. In the end, the grouting material has excellent high fluidity and workability retention, extremely high early and long-term strength, and reliable anti-shrinkage performance, which meets the stringent requirements of modern engineering for the comprehensive performance of grouting materials. Attached Figure Description

[0015] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this invention. For those skilled in the art, other drawings can be obtained based on these drawings.

[0016] Figure 1 This is a schematic diagram of the composition of an embodiment of an ultrafine powder composite high-strength non-shrink grouting material of the present invention. Detailed Implementation

[0017] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings.

[0018] like Figure 1 As shown in the figure, an ultrafine powder composite high-strength non-shrink grouting material provided in this embodiment of the invention is composed of dry powder and mixing water. The dry powder includes a main material, a reinforcing material and a functional additive material. The amount of mixing water is controlled so that the final water-cement ratio of the grout is between 0.12 and 0.20; The main material includes: A composite cementitious material made by mixing silicate cement and sulfoaluminate cement in a mass ratio of (7-9):(1-3); It should be noted that: In the composite cementitious material: The silicate cement is grade 52.5 or higher silicate cement; The sulfoaluminate cement is grade 42.5 rapid-hardening sulfoaluminate cement; Continuously graded fine aggregate with a particle size of 0.15-2.5mm; It should be noted that: The continuously graded fine aggregate is composed of refined quartz sand and waste glass fine sand that has been washed, impurity removed, and magnetically separated at a mass ratio of (6-8):(2-4). The fine aggregate has an overall mud content of ≤0.5% and a SiO2 content of ≥95%; The reinforcing material is a porous functional particle made from recycled micro powder of construction waste, waste glass micro powder, surface-modified plastic micro powder, and anti-corrosion treated straw micro powder. It should be noted that: The steps for fabricating the porous functional particles are as follows: The mixture is made of recycled micro powder from construction waste, waste glass micro powder, surface-modified plastic micro powder and anti-corrosion treated straw micro powder in a mass ratio of (50-60):(25-35):(5-10):(5-10), and 1%-3% of nano SiO2 is added to the mixture. Ultrafine co-grinding to a specific surface area ≥400 m² 2 / kg, and then granulated to form matrix particles, the matrix particles are surface treated and coated with a cement-based active coating; The porous functional particles have a particle size of 0.5-2.0 mm, a porosity of 30%-40%, and a 24-hour water absorption rate of 15%-25%. The surface-modified plastic micro powder is prepared by crushing waste PET or PP plastic, followed by alkaline washing and surface hydrophilic modification with silane coupling agent. The anti-corrosion treated straw powder is obtained by crushing rice straw and then treating it with alkaline solution and organosilicon preservatives for preservation and fiber dissociation. The functional additives include polycarboxylate superplasticizers, composite expanding agents, early strength agents, water-retaining agents, defoamers, and microcapsule foaming agents that release gas in a controlled manner upon contact with water; the composite expanding agent is a compound of calcium sulfoaluminate expanding agents and plastic expanding agents; It should be noted that: The water-reactive microcapsule foaming agent has a core material composed of a complex of sodium bicarbonate and citric acid in a mass ratio of 1:(1-1.2). The coating material for the water-reactive microcapsule foaming agent is water-soluble starch, and the coating layer thickness is 1-20 μm. The microcapsule foaming agent releases bubbles with a diameter ≤100 μm upon contact with water; In the aforementioned functional additive materials: The water reduction rate of the polycarboxylate superplasticizer is ≥25%; The composite expanding agent is composed of calcium sulfoaluminate expanding agent and plastic expanding agent in a mass ratio of (8-12):1; The early-strength agent is calcium formate; In another embodiment of the present invention, the dosage of each functional additive component, based on a percentage of the total weight of the dry powder, is as follows: Polycarboxylate superplasticizer 0.5%-1.2%; Composite expanding agent 1.5%-3.5%; Early-strength agent: 0.5%-1.5%; Water-retaining agent 0.05%-0.15%; Defoamer 0.05%-0.15%; The microcapsule foaming agent is 0.1%-0.5%.

[0019] In another embodiment of the present invention, the composition, based on the total weight percentage of the dry powder, includes: The composite cementitious material comprises 25%-35%; The continuously graded fine aggregate comprises 30%-45%; The porous functional particles comprise 15%-30%; The functional additives comprise 2.7%-6.8%; The balance is unavoidable trace impurities.

[0020] In another embodiment of the present invention, the grouting material meets the following performance indicators: Initial flowability ≥300 mm, flowability retention value ≥260 mm after 30 min; 1-day compressive strength ≥ 30 MPa, 28-day compressive strength ≥ 80 MPa; The vertical free expansion rate over 24 hours is 0.02%-0.10%; The water exudation rate is ≤1.0%.

[0021] In another embodiment of the present invention, the fabrication steps of the porous functional particles are as follows: The mixture is made by mixing recycled micro powder from construction waste (mainly composed of hydrated calcium silicate, calcium hydroxide, etc., with a particle size ≤80μm), waste glass micro powder (particle size ≤75μm), surface-modified plastic micro powder (particle size ≤0.5mm), and anti-corrosion treated straw micro powder (length ≤1mm) in a mass ratio of 55:30:8:7, and then adding 2% of nano-SiO2 (specific surface area ≥200 m² / g) to the mixture. The above mixture was fed into a high-efficiency ultrafine co-grinding mill and ground to a specific surface area ≥400 m² / kg in order to fully activate the activity of solid waste micro powder and achieve uniform dispersion of nano-SiO2. Then, a disc granulator was used to roll the ultrafine powder into matrix particles with a particle size of 0.5-2.0 mm under the condition of atomized water spray. Subsequently, the matrix particles are fed into a surface treatment device, where a thin slurry composed of silicate cement, metakaolin, and water (water-to-solid ratio 0.3) is uniformly sprayed onto their surface, forming a cement-based active coating with a thickness of approximately 20-50 μm. After curing at low temperature (60℃) for 12 hours, the finished porous functional particles are obtained. The porosity of these particles is controlled at around 35%, and the water absorption rate after 24 hours is approximately 20%. These particles can quickly absorb some free water during grout mixing, reducing the risk of initial bleeding in the grout. During the hardening process, the stored water is slowly released, playing an "internal curing" role and effectively reducing autogenous shrinkage.

[0022] In another embodiment of the present invention, the surface-modified plastic micro powder and the anti-corrosion treated straw micro powder are described in detail. The surface-modified plastic micro powder is preferably waste PET bottle flakes mechanically crushed to below 0.5 mm. First, it is soaked and cleaned in a 5% sodium hydroxide solution at 60°C for 30 minutes to remove surface stains and perform slight etching, increasing specific surface area and hydrophilicity. After cleaning and drying, it is surface-sprayed with an ethanol solution (1% concentration) of KH-550 silane coupling agent and dried at 80°C to make the plastic... The surface of the micro powder is grafted with hydrophilic groups, which significantly improves its interfacial bonding with cement paste. The straw micro powder with anti-corrosion treatment is made by cutting and coarsely crushing rice straw, first treating it with 2% sodium hydroxide solution at 80℃ for 2 hours to achieve partial dissolution of hemicellulose and lignin and dissociation of fiber bundles. After treatment, it is washed until neutral and then soaked in organosilicon preservative (such as methyl hydrogen silicone oil emulsion) for 30 minutes, then taken out and dried. This treatment not only maintains the reinforcing effect of the fiber, but also greatly improves its corrosion resistance in alkaline cement environment.

[0023] In another embodiment of the present invention, the water-reactive microcapsule foaming agent is described in detail. Its core material is a dry composite powder composed of food-grade sodium bicarbonate and citric acid in a mass ratio of 1:1.1. The coating material is a water-soluble modified starch. A fluidized bed coating process is used, and by controlling the spray rate of the coating liquid, the temperature of the fluidized air, and the coating time, microcapsules with a coating layer thickness of approximately 10 μm are prepared. The coating layer thickness is crucial for controlling the gas release time; the thickness is adjustable within the range of 1-20 μm to meet different requirements, from several minutes to tens of minutes after mixing. When the microcapsules come into contact with water, the water gradually penetrates and dissolves the starch coating layer. The acid and alkali in the core material react to produce carbon dioxide gas. Through process control, the diameter of the released bubbles can be ≤100 μm, forming uniformly dispersed microbubbles. These bubbles can compensate for plastic settling shrinkage during the plastic stage of the slurry, and their delayed release characteristics can partially compensate for the chemical shrinkage and auto-shrinkage in the early stages of slurry hardening.

[0024] In another embodiment of the present invention, the composition and processing of the continuously graded fine aggregate are described in detail. The continuously graded fine aggregate is composed of commercially available refined quartz sand (SiO2 content ≥99%) and specially treated waste glass fine sand. The waste glass fine sand comes from waste glass bottles that have been crushed, washed, and have their labels and impurities removed. After magnetic separation to remove metal fragments, the 0.15-2.5mm particles are finally screened out. The refined quartz sand and the treated waste glass fine sand are physically mixed at a mass ratio of 7:3. The overall mud content of the aggregate after mixing must be strictly controlled to ≤0.5%, and the SiO2 content ≥95%. The waste glass sand has a smooth surface and high hardness. When mixed with quartz sand, it can optimize the particle size distribution and increase the bulk density. At the same time, its potential alkali reactivity problem is effectively suppressed in the low water-cement ratio and high calcium environment (provided by cement) of this system.

[0025] In another embodiment of the present invention, the selection and function of each functional additive are detailed. The polycarboxylate superplasticizer is a slow-release product with a water reduction rate ≥30% to ensure initial flowability and maintain good slump retention at low water-cement ratios. The composite expanding agent is a mixture of commercially available calcium sulfoaluminate expanding agent (UEA type) and plastic expanding agent (usually aluminum powder or hydroxide) in a mass ratio of 10:1. The calcium sulfoaluminate expanding agent mainly expands in the early hardening stage (1-7 days) by forming ettringite, compensating for hardening shrinkage. The plastic expansion agent releases hydrogen gas to produce micro-expansion while the slurry is still plastic (within a few hours after mixing), compensating for plastic shrinkage. The combination of the two achieves a connection between the expansion timing. The early strength agent is calcium formate, which can accelerate the early hydration of silicate cement, especially sulfoaluminate cement. The water-retaining agent is hydroxypropyl methylcellulose (HPMC), which can effectively reduce water evaporation and bleeding with a very low dosage. The defoamer is an organosilicon powder defoamer, which is used to eliminate excessively large air bubbles introduced by the high-efficiency water-reducing agent and microcapsule foaming agent, ensuring the quality of the air bubbles.

[0026] In another embodiment of the present invention, the specific dosage range of each functional additive component is specified (in percentage of the total weight of the dry powder): The dosages are as follows: polycarboxylate superplasticizer 0.5%-1.2%; composite expanding agent 1.5%-3.5%; early strength agent (calcium formate) 0.5%-1.5%; water-retaining agent (HPMC) 0.05%-0.15%; defoamer 0.05%-0.15%; and microcapsule foaming agent 0.1%-0.5%. These dosages are determined based on extensive testing to ensure the optimal balance of various properties at low water-cement ratios. For example, too low a dosage of water-reducing agent will result in insufficient fluidity, while too high a dosage may cause segregation. The dosage of microcapsule foaming agent needs to be precisely controlled; too little will result in insufficient expansion compensation, while too much may form harmful pores and reduce strength.

[0027] In another embodiment of the present invention, a typical dry powder composition ratio (by weight percentage of total dry powder) is provided: 30% composite cementitious material; 40% continuously graded fine aggregate; 25% porous functional particles; and 4.8% functional additives (total) (of which: 1.0% polycarboxylate superplasticizer, 2.5% composite expanding agent, 1.0% calcium formate, 0.1% water-retaining agent, 0.1% defoamer, and 0.1% microencapsulated foaming agent); the balance is unavoidable trace impurities (such as those introduced from the raw materials, <0.1%). This ratio reflects the coordination between the components. The cementitious material and fine aggregate constitute the main framework, the porous functional particles serve as functional fillers and reinforcements, and the functional additives precisely regulate various properties.

[0028] In another embodiment of the present invention, the performance indicators that the grouting material should achieve are specified as follows: Initial flowability ≥320 mm, 30 min flowability retention ≥280 mm; 1-day compressive strength ≥ 35 MPa, 28-day compressive strength ≥ 85 MPa; The vertical free expansion rate over 24 hours is 0.05%-0.08%; The water seepage rate is ≤0.5%; These indicators all exceed the requirements for the highest grade grouting material in the national standard, demonstrating the technical advantages of this invention.

[0029] In another embodiment of the present invention, the specifications of the two types of cement in the composite cementitious material are defined. The silicate cement is preferably P·II 52.5R type silicate cement, which has high early strength and stable chemical composition. The sulfoaluminate cement is 42.5 grade rapid hardening sulfoaluminate cement (R·SAC 42.5), which is characterized by rapid setting and hardening, extremely rapid early strength development and micro-expansion. The mixing ratio of the two (e.g., 8:2) needs to be finely adjusted according to the construction environment temperature and strength development requirements. When the temperature is low, the proportion of sulfoaluminate cement can be appropriately increased to accelerate the early reaction.

[0030] Example 1 (Preferred Formula) This embodiment demonstrates the optimal formulation of the present invention, reflecting the synergistic effect among the components.

[0031] Dry powder composition (by weight percentage): Composite cementitious material: 30.0% (of which P·II 52.5R silicate cement: 42.5 rapid hardening sulfoaluminate cement = 8:2); Continuously graded fine aggregate: 40.0% (of which refined quartz sand: treated waste glass sand = 7:3); Porous functional particles: 25.0% (composition: 55% construction waste powder, 30% waste glass powder, 8% modified PET powder, 7% anti-corrosion straw powder, and 2% nano-SiO2 added externally); Functional additives: 5.0%; Polycarboxylate superplasticizer (water reduction rate 30%): 1.0%; Composite expanding agent (calcium sulfoaluminate: plastic expanding agent = 10:1): 2.5%; Early-strength agent (calcium formate): 1.0%; Water-retaining agent (HPMC): 0.1%; Defoamer (silicone-based): 0.1%; Microencapsulation foaming agent (coating thickness ~10μm): 0.3%; Performance test results: Initial flowability: 335 mm; 30-minute flow retention: 285 mm; 1-day compressive strength: 38.5 MPa; 28-day compressive strength: 89.2 MPa; 24-hour vertical free expansion rate: 0.06%; 28-day drying shrinkage (compared to 24-hour age): +0.02% (slight expansion); Water seepage rate: 0.3%.

[0032] Example 2 (Proportioning endpoint A) This embodiment demonstrates the material's performance when the amount of cementitious material is relatively large and the amount of porous functional particles is relatively small.

[0033] Dry powder composition (by weight percentage): Composite cementitious material: 35.0% (cement ratio same as in Example 1); Continuously graded fine aggregate: 45.0% (sand ratio same as in Example 1); Porous functional particles: 15.0% (composition same as in Example 1); Functional additives: 5.0% (component ratios are the same as in Example 1); Performance test results: Initial flowability: 310 mm; 30-minute flow retention: 265 mm; 1-day compressive strength: 40.2 MPa (higher early strength); 28-day compressive strength: 92.1 MPa (highest ultimate strength); 24-hour vertical free expansion rate: 0.05%; 28-day drying shrinkage rate: -0.01% (virtually no shrinkage); Exudation rate: 0.8% (exudation increased slightly).

[0034] Example 3 (Endpoint B of the mixing ratio) This embodiment demonstrates the material's performance and its behavior under high solid waste content when the amount of cementitious material is small and the amount of porous functional particles is large.

[0035] Dry powder composition (by weight percentage): Composite cementitious material: 25.0% (cement ratio same as in Example 1); Continuously graded fine aggregate: 45.0% (sand ratio same as in Example 1); Porous functional particles: 27.0% (composition same as in Example 1); Functional additives: 3.0% (adjusted as follows to maintain fluidity: water-reducing agent 1.2%, composite expanding agent 1.5%, calcium formate 0.5%, water-retaining agent 0.05%, defoamer 0.05%, microcapsules 0.1%). Performance test results: Initial flowability: 305 mm; 30-minute flow retention: 275 mm; 1-day compressive strength: 32.1 MPa (early strength is somewhat reduced); 28-day compressive strength: 81.5 MPa (still meets high strength requirements); 24-hour vertical free expansion rate: 0.07%; 28-day drying shrinkage: +0.04% (expansion maintained well); Water leakage rate: 0.2% (lowest water leakage rate).

[0036] Comparative Example 1 (Basic Control) This comparative example adopts the traditional high-strength grouting material approach, without using the porous functional particles and microcapsule foaming agent of this invention, in order to highlight the advanced nature of the overall technical solution of this invention.

[0037] Dry powder composition: P·II 52.5R Portland cement: 32.0%; Quartz sand (0.15-2.5mm): 58.0%; Silica fume: 5.0%; Polycarboxylate superplasticizer: 1.2%; Calcium sulfoaluminate-based expanding agent (single addition): 3.0%; Calcium formate: 1.0%; Defoamer: 0.1%; HPMC: 0.05%; Performance test results: Initial flowability: 320 mm; 30-minute flow retention: 250 mm; 1-day compressive strength: 35.0 MPa; 28-day compressive strength: 85.0 MPa; 24-hour vertical free expansion rate: 0.04%; 28-day drying shrinkage rate: -0.05% (significant shrinkage occurred); Water exudation rate: 1.5%.

[0038] Comparative analysis: Compared with Example 1, although Comparative Example 1 achieved higher strength, it showed shrinkage after 28 days and had a significantly higher water bleeding rate. This indicates that the dual expansion system of the present invention and the "internal curing" effect of porous particles, while ensuring ultra-high strength, achieve long-term volume stability and water bleeding resistance that are difficult to achieve with ordinary formulations.

[0039] Comparative Example 2 (without microcapsule foaming agent) This comparative example is based on Example 1, but the microencapsulated foaming agent is removed and replaced with an equal amount of quartz sand to verify the key role of the microencapsulated foaming agent in compensating for early shrinkage.

[0040] Dry powder composition: Except for not using 0.3% microencapsulated foaming agent and increasing the continuous graded fine aggregate to 40.3%, it is completely the same as in Example 1.

[0041] Performance test results: Initial flowability: 340 mm (slightly improved due to the absence of foaming agent interference); 30-minute flow retention: 290 mm; 1-day compressive strength: 39.0 MPa; 28-day compressive strength: 88.5 MPa; 24-hour vertical free expansion rate: 0.03% (significantly lower than in Example 1); 28-day drying shrinkage rate: -0.03% (shrinkage trend observed); Water exudation rate: 0.4%.

[0042] Comparative analysis: Compared with Example 1, Comparative Example 2 showed a significantly reduced early (24h) expansion rate and long-term shrinkage. This demonstrates that the micro-expansion provided by the microencapsulated foaming agent, precisely matched to the plastic-hardening transition stage, is crucial for compensating for the chemical shrinkage and auto-shrinkage during this stage, and is an indispensable part of achieving "shrinkage-free" results.

[0043] Comparative Example 3 (non-porous functional particles) Based on Example 1, this comparative example replaces all porous functional particles with ordinary quartz sand of equal mass to verify the role of porous functional particles in "internal maintenance," enhancing, and regulating microstructure.

[0044] Dry powder composition: 25% of porous functional particles are replaced with 25% (0.5-2.0mm) quartz sand, the total proportion of fine aggregate is adjusted to 65%, and the rest is exactly the same as in Example 1.

[0045] Performance test results: Initial flowability: 345 mm; 30-minute flow retention: 270 mm; 1-day compressive strength: 36.8 MPa; 28-day compressive strength: 86.0 MPa; 24-hour vertical free expansion rate: 0.08% (expansion rate is not low); 28-day drying shrinkage rate: -0.08% (most severe shrinkage); Exudation rate: 1.8% (severe exudation).

[0046] Comparative Analysis: Compared with Example 1, Comparative Example 3 exhibited the most significant problems with long-term drying shrinkage and water bleeding. Although the expansion agent system was still functioning (the 24-hour expansion rate was not low), the lack of "internal curing" moisture supply from the porous particles resulted in significant self-shrinkage and drying shrinkage of the slurry during the later hardening process. Simultaneously, its high water bleeding rate also demonstrates the crucial role of porous particles in absorbing free water and improving homogeneity.

[0047] Comparative Example 4 (Control for Imbalanced Proportions) This comparative example is intended to illustrate that it is not simply a matter of piling up the components of this invention; a reasonable ratio must be maintained between the components. This ratio is intentionally set to an unreasonable proportion (too little cementitious material and too much porous particles and additives).

[0048] Dry powder composition: Composite cementitious materials: 20.0%; Continuously graded fine aggregate: 40.0%; Porous functional particles: 35.0%; Functional additives: 5.0% (same proportion as in Example 1); Performance test results: Initial flowability: 280 mm (poor flowability); 30-minute flow retention: 230 mm; 1-day compressive strength: 25.4 MPa (low early strength); 28-day compressive strength: 65.0 MPa (not meeting high strength requirements); 24-hour vertical free expansion rate: 0.12% (expansion rate is too high); 28-day drying shrinkage rate: +0.06%; Water seepage rate: 0.1%.

[0049] Comparative analysis: Comparative Example 4 demonstrates that when there is too little main cementitious material and too much water-absorbing porous particles, workability deteriorates and the strength matrix is ​​insufficient. Although shrinkage control is acceptable, the core "high strength" indicator cannot be met. This conversely proves the necessity and scientific validity of the proportion range (25-35% cementitious material, 15-30% porous particles) defined in the claims and Examples 1-3.

[0050] Comparison Table of Examples and Comparative Examples in conclusion: 1. Example 1 has the best overall performance. Compared with the traditional Comparative Example 1, it has significant advantages in volume stability and water resistance while maintaining comparable strength. 2. Microcapsules (Comparative Example 2) and porous particles (Comparative Example 3) are key to achieving zero shrinkage and low water leakage; the absence of either will lead to performance degradation. 3. The proportions must be within a reasonable range (Comparative Example 4), otherwise the strength will not meet the standard, which confirms the scientific nature of the formula design; 4. Examples 2 and 3 demonstrate the flexibility of the formulation, which can be adjusted according to the needs and different engineering scenarios.

[0051] Working principle: Mixing stage: When dry powder is mixed with water, polycarboxylate superplasticizer quickly disperses cement particles and releases the encapsulated water, giving the paste high fluidity at an extremely low water-cement ratio (0.12-0.20). The porous functional particles quickly absorb some of the free water, reducing the risk of surface bleeding. The plastic expansion agent begins to react slowly, releasing trace amounts of gas to compensate for the plastic settling of the mixture when it is left to stand. Early stage of plastic hardening transition: Silicate cement and sulfoaluminate cement begin to hydrate, and calcium formate accelerates this process. The slurry gradually loses its fluidity, and calcium sulfoaluminate-based expansive agents begin to form ettringite, resulting in early expansion. At the same time, the coating layer of the microcapsule foaming agent is gradually dissolved by water, and the core material reacts to release carbon dioxide microbubbles. The timing of the introduction of these microbubbles is designed to match the slurry setting process, further compensating for the chemical shrinkage and plastic shrinkage at this stage. The moisture stored in the porous functional particles begins to slowly diffuse outward, providing an internal water source for the hydration of the surrounding cement particles. Hardening and Development Stages (Mid-to-Late Stages): As cement continues to hydrate, the strength of the paste increases rapidly. The active coating on the surface of porous functional particles participates in hydration, improving the interfacial transition zone. The moisture stored inside the particles continuously releases, providing an "internal curing" effect and promoting further hydration of unhydrated cement particles. This significantly reduces the autogenous shrinkage common in high-strength systems. The calcium sulfoaluminate component in the composite expansion agent continues to generate ettringite, providing a stable source of mid-term expansion and compensating for the drying shrinkage trend. The pores of the porous particles themselves and the microbubbles generated by the microcapsules form a uniform and closed microporous structure in the hardened paste. This not only does not significantly reduce strength (because the pore size is small and dispersed), but also buffers internal stress, inhibits the generation and propagation of microcracks, optimizes the pore structure, and thus improves crack resistance and durability. Long-term performance phase: The system is fully hydrated, forming a dense, high-strength matrix rich in micropores (beneficial pores). The porous functional particles are firmly bonded to the cement stone interface, the solid waste components are stabilized and solidified, and no harmful substances are leached out. The entire system achieves volume stability throughout the entire process from the plastic stage to long-term service, exhibiting ultra-high strength, high toughness and excellent durability.

[0052] The foregoing has only described certain exemplary embodiments of the present invention by way of illustration. Undoubtedly, those skilled in the art can modify the described embodiments in various ways without departing from the spirit and scope of the present invention. Therefore, the foregoing drawings and descriptions are illustrative in nature and should not be construed as limiting the scope of protection of the claims of the present invention.

Claims

1. A high-strength, non-shrink grouting material composed of ultrafine powder composite material, comprising dry powder and mixing water, wherein the dry powder comprises a main material, reinforcing material, and functional additive material, characterized in that: The amount of mixing water is controlled so that the final water-cement ratio of the grout is between 0.12 and 0.20; The main material includes: A composite cementitious material made by mixing silicate cement and sulfoaluminate cement in a mass ratio of (7-9):(1-3); Continuously graded fine aggregate with a particle size of 0.15-2.5mm; The reinforcing material is a porous functional particle made from recycled micro powder of construction waste, waste glass micro powder, surface-modified plastic micro powder, and anti-corrosion treated straw micro powder. The functional additives include polycarboxylate superplasticizers, composite expanding agents, early strength agents, water-retaining agents, defoamers, and microcapsule foaming agents that release gas in a controlled manner upon contact with water; the composite expanding agent is a compound of calcium sulfoaluminate expanding agents and plastic expanding agents.

2. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, The steps for fabricating the porous functional particles are as follows: The mixture is made of recycled micro powder from construction waste, waste glass micro powder, surface-modified plastic micro powder and anti-corrosion treated straw micro powder in a mass ratio of (50-60):(25-35):(5-10):(5-10), and 1%-3% of nano SiO2 is added to the mixture. Ultrafine co-grinding to a specific surface area ≥400 m² 2 / kg, and then granulated to form matrix particles, the matrix particles are surface treated and coated with a cement-based active coating; The porous functional particles have a particle size of 0.5-2.0 mm, a porosity of 30%-40%, and a 24-hour water absorption rate of 15%-25%.

3. The ultrafine powder composite high-strength non-shrink grouting material according to claim 2, characterized in that, The surface-modified plastic micro powder is prepared by crushing waste PET or PP plastic, followed by alkaline washing and surface hydrophilic modification with silane coupling agent. The anti-corrosion treated straw powder is obtained by crushing rice straw and then treating it with alkaline solution and organosilicon preservatives for preservation and fiber dissociation.

4. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, The water-reactive microcapsule foaming agent has a core material composed of a complex of sodium bicarbonate and citric acid in a mass ratio of 1:(1-1.2). The coating material for the water-reactive microcapsule foaming agent is water-soluble starch, and the coating layer thickness is 1-20 μm. The microcapsule foaming agent releases bubbles with a diameter ≤100 μm upon contact with water.

5. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, The continuously graded fine aggregate is composed of refined quartz sand and waste glass fine sand that has been washed, impurity removed, and magnetically separated at a mass ratio of (6-8):(2-4). The fine aggregate has an overall mud content of ≤0.5% and a SiO2 content of ≥95%.

6. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, In the aforementioned functional additive materials: The water reduction rate of the polycarboxylate superplasticizer is ≥25%; The composite expanding agent is composed of calcium sulfoaluminate expanding agent and plastic expanding agent in a mass ratio of (8-12):1; The early strength agent is calcium formate.

7. The ultrafine powder composite high-strength non-shrink grouting material according to claim 6, characterized in that, The dosage of each functional additive component, calculated as a percentage of the total weight of the dry powder, is as follows: Polycarboxylate superplasticizer 0.5%-1.2%; Composite expanding agent 1.5%-3.5%; Early-strength agent: 0.5%-1.5%; Water-retaining agent 0.05%-0.15%; Defoamer 0.05%-0.15%; The microcapsule foaming agent is 0.1%-0.5%.

8. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, Its composition, based on the total weight percentage of dry powder, includes: The composite cementitious material comprises 25%-35%; The continuously graded fine aggregate comprises 30%-45%; The porous functional particles comprise 15%-30%; The functional additives comprise 2.7%-6.8%; The balance is unavoidable trace impurities.

9. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, The grouting material meets the following performance indicators: Initial flowability ≥300 mm, flowability retention value ≥260 mm after 30 min; 1-day compressive strength ≥ 30 MPa, 28-day compressive strength ≥ 80 MPa; The vertical free expansion rate over 24 hours is 0.02%-0.10%; The water exudation rate is ≤1.0%.

10. The ultrafine powder composite high-strength non-shrink grouting material according to claim 1, characterized in that, In the composite cementitious material: The silicate cement is grade 52.5 or higher silicate cement; The sulfoaluminate cement is grade 42.5 rapid-hardening sulfoaluminate cement.

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