Green grouting material for rapid repair of bridge cracks based on modified ceramic powder and preparation method thereof

Abstract

The application belongs to the technical field of bridge structure repairing materials, and provides a green grouting material for rapid repairing of bridge cracks based on modified ceramic powder and a preparation method thereof.The grouting material is a dry mixture, a cementing system of which is composed of ordinary Portland cement, slag powder, sulphoaluminate cement, gypsum and modified ceramic powder, and is matched with polycarboxylate superplasticizer, anti-segregation thickening agent and defoaming agent; the modified ceramic powder has a core-shell composite structure, the ceramic core is derived from waste ceramic powder grinding and grading, an inorganic reaction shell layer is generated in situ under slurry conditions, the shell layer contains calcium-silicon-aluminum gel phase, and a sulphate source is introduced during preparation; the preparation method comprises the following steps: preparing a ceramic core slurry, adding calcium-containing and silicon-containing components to form a shell layer, adding an aluminum-containing component to regulate the composition of the shell layer, adding a sulphate source, solid-liquid separation, drying and depolymerization grinding to obtain the modified ceramic powder, then dry mixing the modified ceramic powder with each cementing component and adding the admixture to obtain the grouting material.

Description

Green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method Technical Field

[0001] This invention belongs to the technical field of bridge structure repair materials, and relates to a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method. Background Technology

[0002] During bridge service, concrete components are prone to developing various forms of cracks under environmental conditions such as vehicle loads, temperature gradients, wet-dry cycles, and freeze-thaw cycles. Once a crack penetrates or connects to the outside environment, moisture and chloride salts can enter, accelerating steel corrosion and interface deterioration, leading to problems such as spalling, leakage, and decreased durability. To restore the integrity of the component and block the corrosion pathway, pressure grouting is often used to repair cracks in engineering. The grouting material needs to balance injectability, stability, and post-hardening performance: it must be able to penetrate smoothly into smaller cracks and maintain continuous flow, while avoiding bleeding, segregation, and settlement blockage during injection. Simultaneously, the hardened material should possess mechanical and volumetric stability characteristics compatible with the existing concrete to reduce the risk of re-cracking after repair.

[0003] Existing crack grouting systems mainly include epoxy-based, organic acrylate-based, and cement-based inorganic materials. Epoxy-based and acrylate-based grouting materials generally have good permeability and adhesion, but they suffer from high cost, high construction sensitivity, limited adaptability to damp interfaces, and some systems may introduce volatility or safety management requirements. Cement-based grouting materials have a wide range of raw material sources, good durability, and strong compatibility with concrete, making them widely used in engineering. However, in the grouting of micro-cracks, they still face the contradiction between particle size and rheological control. Furthermore, common systems are prone to insufficient flow retention, difficulty in controlling segregation and bleeding, and early volume changes leading to interfacial micro-cracks under low water-cement ratio conditions.

[0004] To address these issues, existing technologies typically optimize grouting by employing fine cement, incorporating mineral admixtures, introducing early-strength or expansive components, and combining polycarboxylate superplasticizers and thickeners. However, relying solely on additives or conventional admixtures often fails to simultaneously meet the synergistic requirements of groutability, anti-segregation, and early structure formation. Furthermore, while the recycling of solid waste such as waste ceramics for cement-based materials offers environmental and cost advantages, their powders are often irregularly shaped and have strong interfacial inertness. Direct use as admixtures can easily lead to reduced fluidity, insufficient particle dispersion, and weakened interfacial transition zones, limiting their application in crack grouting materials. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method. This grouting material is a dry-mix system, comprising a cementitious system composed of cement, slag powder, sulfoaluminate cement, gypsum, and core-shell structured modified ceramic powder, along with water-reducing, thickening, and defoaming additives. The modified ceramic powder is obtained by grinding and classifying waste ceramics to obtain ceramic core powder. Under slurry conditions, an inorganic reactive shell layer containing a calcium-silica-alumina gel phase is generated in situ, and a sulfate source is introduced. After solid-liquid separation, drying, and deagglomeration grinding, the resulting material is dry-mixed to obtain the grouting material, thus meeting the needs of actual production.

[0006] To achieve this objective, the present invention adopts the following technical solution:

[0007] In a first aspect, the present invention provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder. The green grouting material is a dry mix comprising a cementitious material and an additive. The cementitious material is composed of the following components by mass: 25-45 parts of ordinary silicate cement, 5-25 parts of slag powder, 3-15 parts of sulfoaluminate cement, 1-6 parts of gypsum, and 20-45 parts of modified ceramic powder. The sum of the mass parts of each component of the cementitious material is 100 parts.

[0008] The admixtures, calculated per 100 parts of cementitious material, include: 0.20-0.80 parts of polycarboxylate superplasticizer, 0.01-0.10 parts of anti-segregation thickener, and 0.005-0.08 parts of defoamer;

[0009] The modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reactive shell layer, wherein:

[0010] The ceramic core powder is waste ceramic powder;

[0011] The inorganic reaction shell coats the surface of the ceramic core powder, and the shell thickness is 0.05-3.0 μm;

[0012] The inorganic reaction shell contains a Ca–Si–Al gel phase;

[0013] A sulfate source is added during the preparation of the modified ceramic powder. The sulfate source is gypsum and / or sodium sulfate. The amount of sulfate source added is 0.2-8.0 wt.% based on the mass of the ceramic core powder and the solid content.

[0014] Preferably, the specific surface area of ​​the modified ceramic powder is 1.5-8.0 m². 2 / g, the particle size distribution of the waste ceramic powder satisfies D50 of 3-12μm and D90≤35μm.

[0015] Preferably, the inorganic reaction shell further comprises an ettringite crystalline phase and / or a calcium carbonate crystalline phase.

[0016] Preferably, the gypsum is dihydrate gypsum and / or hemihydrate gypsum.

[0017] Preferably, when the green grouting material for rapid repair of bridge cracks based on modified ceramic powder is mixed with mixing water to prepare the grouting slurry, the water-cement ratio is 0.26-0.36.

[0018] Secondly, the present invention provides a method for preparing a green grouting material for rapid repair of bridge cracks based on modified ceramic powder, comprising the following steps:

[0019] S1. Waste ceramics are ground and classified to obtain ceramic core powder, wherein the particle size distribution of the ceramic core powder satisfies D50 of 3-12μm and D90≤35μm;

[0020] S2. Mix the ceramic core powder with water to form a slurry;

[0021] S3. Add calcium-containing components and silicon-containing components to the slurry and stir to react, so that an inorganic reaction shell layer is formed on the surface of the ceramic core powder to obtain system A, wherein the calcium-containing components are calcium hydroxide and / or calcium oxide, and the silicon-containing components are sodium silicate and / or silica sol.

[0022] S4. Add aluminum-containing components to system A and stir to react, to obtain system B, wherein the aluminum-containing components are aluminate cement and / or sodium aluminate.

[0023] S5. Add a sulfate source to system B and mix and react to obtain system C. The sulfate source is gypsum and / or sodium sulfate.

[0024] S6. Solid-liquid separation and drying of system C, followed by deagglomeration and grinding to obtain modified ceramic powder;

[0025] S7. Weigh and dry mix ordinary silicate cement, slag powder, sulfoaluminate cement, gypsum and the modified ceramic powder according to the mass fractions specified in claim 1 to obtain a cementitious material mixture.

[0026] S8. Add polycarboxylate superplasticizer, anti-segregation thickener and defoamer to the cementitious material mixture and mix evenly to obtain green grouting material.

[0027] Preferably, in S2, the solid content of the slurry is 15-45 wt.%, and in S3, based on the mass of the ceramic core powder, the amount of calcium-containing component added is 0.5-8.0 wt.%, and the amount of silicon-containing component added is 0.2-6.0 wt.% based on the SiO2 solid content.

[0028] Preferably, in S4, based on the mass of the ceramic core powder, the amount of aluminum-containing component added is 0.05-3.0 wt.% according to the Al2O3 solid content.

[0029] Preferably, in S3-S5, the reaction temperature is 15-60℃ and the reaction time is 10-180min.

[0030] Preferably, in S6, the drying method is one of spray drying, fluidized bed drying or belt drying, and the deagglomeration grinding is an air jet mill or a classifying mill.

[0031] In the preparation stage of modified ceramic powder, the surface of waste ceramic powder is mainly composed of silicon-oxygen and aluminum-oxygen frameworks, with hydroxylation sites and defect sites present. Calcium-containing components undergo hydration and dissociation upon entering the aqueous phase, providing calcium ions and a high-alkalinity environment. Silicon-containing components exist under alkaline conditions as soluble silicate or silanol condensation precursors. Calcium ions and silicate undergo heterogeneous nucleation and deposition at the solid-liquid interface, preferentially forming a calcium-silicon hydrated gel phase on the ceramic particle surface. When aluminum-containing components are added, aluminate or aluminate hydrates participate in the coordination and polymerization of the gel network, forming a calcium-silicon-aluminum hydrated gel phase, transforming the deposited layer from a single calcium-silicon hydrated network into an aluminum-containing cross-linked network. Because the reaction occurs on the ceramic particle surface, a chemical connection is established between the deposited layer and the ceramic substrate through surface hydroxyl condensation of the silicon-oxygen framework, calcium bridging coordination, and local dissolution and redeposition processes. This transforms the shell from a simple physical cover into a continuous inorganic phase generated by interfacial reactions. After the introduction of the sulfate source, a calcium aluminate hydrate phase containing sulfate is formed in the local environment where calcium ions and aluminate ions coexist. Some of these hydrates precipitate out as ettringite crystals and coexist with the gel phase. Sulfate ions can also exist in the gel pores and surface adsorption layer in ionic form, forming a migratory sulfate reservoir. After solid-liquid separation, drying, and deagglomeration grinding, the resulting powder retains a core-shell structure: the core is ceramic particles, and the outer layer is a composite shell consisting of a calcium-containing silica-alumina gel phase and a sulfate-containing aluminate hydrate phase.

[0032] When the green grouting material comes into contact with the mixing water, the ordinary silicate cement mineral phase dissolves and releases calcium ions, hydroxide ions, and silicate ions, while the sulfoaluminate cement dissolves and releases aluminate ions and calcium ions, forming ettringite in the presence of sulfate ions. The slag powder undergoes latent hydration under alkaline conditions and with the help of a calcium source, forming an aluminum-containing calcium-silica hydration gel phase. The modified ceramic powder plays a role in this system through interfacial hydration bonding and local ion regulation. Its shell itself contains a calcium-silica-alumina gel phase, which can serve as a heterogeneous nucleation substrate for the deposition of hydration products. The calcium-silica hydration gel and aluminum-containing gel generated during the cement and slag hydration process continue to deposit on the shell surface, resulting in interconnected gel networks. This creates a continuous inorganic phase connection between the ceramic particles and the matrix hydration products, eliminating the need for physical interlocking at the interface to transfer stress and block pathways. In the early stages, sulfate ions introduced into the shell react with calcium ions and aluminate ions in the solution to form ettringite, which grows in the pore space, accompanied by changes in the ionic strength of the solution and adjustments in the volume distribution of hydration products. This process alters the bridging and flocculation state between particles in the slurry and, together with the anti-segregation thickener, restricts free water migration and solid-phase sedimentation. In the early stages of hydration, the polycarboxylate-based water-reducing agent adsorbs onto the solid surface through carboxyl groups and calcium ions, providing steric hindrance dispersion. The calcium-containing silica-alumina gel phase and surface hydroxyl sites in the modified shell participate in the adsorption equilibrium of the water-reducing agent, enabling a repeatable adsorption and desorption process between the ceramic powder and cement particles, thereby affecting the particle dispersion and flow retention. The defoamer alters the gas-liquid interfacial tension and promotes bubble coalescence and escape, reducing the pore volume occupied by bubbles in the slurry, ultimately forming a multiphase solidified structure composed of the calcium-silica-alumina gel phase, the ettringite phase, and unreacted ceramic cores.

[0033] Compared with existing technologies, the beneficial effects of this invention are as follows: The green grouting material of this invention adopts a core-shell structure modified ceramic powder, cement, slag powder, sulfoaluminate cement, and gypsum to form a composite cementitious system. The inorganic reaction shell of the modified powder acts as a heterogeneous nucleation and deposition interface during the material hydration process, allowing hydration products to grow continuously on the surface of ceramic particles and connect with the matrix gel network, reducing the interfacial discontinuity between ceramic particles and cement stone, and reducing the formation of permeation channels at the interface. The sulfate source introduced into the shell works in conjunction with the aluminate hydration reaction to regulate the early ionic environment and the hydration phase formation path, and, together with the thickening system, inhibits grout bleeding and particle sedimentation, which is beneficial to stable transport and filling during the grouting process. The modified ceramic powder is derived from the resource-based treatment of waste ceramics, reducing the consumption of natural mineral admixtures and the pressure of solid waste storage. The material system is an inorganic cementitious system, suitable for the durability requirements of bridge crack repair scenarios. Attached Figure Description

[0034] Figure 1 is a SEM image of the microstructure of the grouting material after hydration and hardening provided in Embodiment 1 of the present invention.

[0035] Figure 2 is a microstructure SEM image of the contact area between the grouting material and the substrate provided in Embodiment 1 of the present invention. Detailed Implementation

[0036] The technical solutions of the present invention will be described in detail below with reference to specific embodiments and accompanying drawings. The embodiments described herein are specific implementations of the present invention, used to illustrate the concept of the present invention; these descriptions are explanatory and exemplary, and should not be construed as limiting the implementation methods or the scope of protection of the present invention. In addition to the embodiments described herein, those skilled in the art can employ other obvious technical solutions based on the content disclosed in the claims and specification of this application. These technical solutions include those that make any obvious substitutions and modifications to the embodiments described herein.

[0037] The chemical reagents used in the embodiments and comparative examples of this invention are all commercially available products and have not undergone any further purification treatment.

[0038] Example 1

[0039] This embodiment provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method, specifically including:

[0040] The green grouting material is a dry mix, comprising cementitious materials and additives; the cementitious materials are composed of the following components by mass: 25 parts ordinary silicate cement, 25 parts slag powder, 15 parts sulfoaluminate cement, 5 parts gypsum, and 30 parts modified ceramic powder.

[0041] The admixtures, calculated per 100 parts of cementitious material, include: 0.80 parts of polycarboxylate superplasticizer, 0.01 parts of anti-segregation thickener, and 0.08 parts of defoamer;

[0042] The modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reactive shell layer, wherein:

[0043] The ceramic core powder is waste ceramic powder, and the particle size distribution satisfies D50 of 12μm and D90≤35μm;

[0044] The inorganic reaction shell is coated on the surface of the ceramic core powder, and the shell thickness is 0.05 μm;

[0045] The inorganic reaction shell contains a Ca-Si-Al gel phase;

[0046] A sulfate source, gypsum, is added during the preparation of the modified ceramic powder. The amount of sulfate source added, based on the mass of the ceramic core powder and calculated by solid content, is 8.0 wt.%.

[0047] The specific surface area of ​​the modified ceramic powder is 1.5 m².2 / g;

[0048] The inorganic reaction shell also contains an ettringite crystalline phase;

[0049] The gypsum is dihydrate gypsum;

[0050] When the green grouting material for rapid repair of bridge cracks based on modified ceramic powder is mixed with mixing water to prepare the grouting slurry, the water-cement ratio is 0.36.

[0051] The preparation method of green grouting material for rapid repair of bridge cracks based on modified ceramic powder includes the following steps:

[0052] S1. Waste ceramics are ground and classified to obtain ceramic core powder, wherein the particle size distribution of the ceramic core powder satisfies D50 of 3-12μm and D90≤35μm;

[0053] S2. Mix the ceramic core powder obtained in step S1 with water to form a slurry with a solid content of 45 wt.%;

[0054] S3. Add calcium-containing components and silicon-containing components to the slurry and stir to react, so that an inorganic reaction shell layer is formed on the surface of the ceramic core powder to obtain system A, wherein the calcium-containing component is calcium hydroxide and the silicon-containing component is sodium silicate;

[0055] S4. Add aluminum-containing components to system A and stir to react, to obtain system B, wherein the aluminum-containing components are aluminate cement;

[0056] S5. Add a sulfate source to system B and mix and react to obtain system C, wherein the sulfate source is gypsum.

[0057] S6. Solid-liquid separation and drying of system C, followed by deagglomeration and grinding to obtain modified ceramic powder, wherein the thickness of the inorganic reaction shell is 0.05-3.0 μm;

[0058] S7. Ordinary silicate cement, slag powder, sulfoaluminate cement, gypsum and the modified ceramic powder are measured and dry-mixed according to the mass parts to obtain a cementitious material mixture;

[0059] S8. Add polycarboxylate superplasticizer, anti-segregation thickener and defoamer to the cementitious material mixture and mix evenly to obtain green grouting material;

[0060] In step S3, based on the mass of the ceramic core powder, the amount of calcium-containing component added is 0.5 wt.%; the amount of silicon-containing component added is 6.0 wt.% based on the SiO2 solid content.

[0061] In step S4, based on the mass of the ceramic core powder, the amount of aluminum-containing component added is 3.0 wt.% based on the Al2O3 solid content.

[0062] The reaction temperature for steps S3-S5 is 60℃, and the reaction time is 10 min.

[0063] The drying method in step S6 is spray drying, and the deagglomeration grinding in step S6 is air jet milling.

[0064] Figure 1 is a SEM image of the microstructure of the grouting material after hydration and hardening provided in this embodiment; Figure 2 is a SEM image of the microstructure of the contact area between the grouting material and the matrix provided in this embodiment. It can be seen that the hydration products are continuously generated in the particle / matrix neighborhood and are connected in a bridging manner.

[0065] Example 2

[0066] This embodiment provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method, specifically including:

[0067] The green grouting material is a dry mix, including cementitious materials and additives; the cementitious material is composed of the following components by mass: 45 parts ordinary silicate cement, 10 parts slag powder, 3 parts sulfoaluminate cement, 1 part gypsum, and 41 parts modified ceramic powder.

[0068] The admixture, calculated per 100 parts of cementitious material, includes: 0.20 parts of polycarboxylate superplasticizer, 0.10 parts of anti-segregation thickener, and 0.005 parts of defoamer;

[0069] The modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reactive shell layer, wherein:

[0070] The ceramic core powder is waste ceramic powder, and the particle size distribution satisfies D50 of 3μm and D90≤35μm;

[0071] The inorganic reaction shell is coated on the surface of the ceramic core powder, and the shell thickness is 3.0 μm;

[0072] The inorganic reaction shell contains a Ca-Si-Al gel phase;

[0073] A sulfate source, sodium sulfate, is added during the preparation of the modified ceramic powder. The amount of sulfate source added, based on the mass of the ceramic core powder and calculated by solid content, is 0.2 wt.%.

[0074] The specific surface area of ​​the modified ceramic powder is 8.0 m². 2 / g;

[0075] The inorganic reaction shell also contains a calcium carbonate crystalline phase;

[0076] The gypsum is hemihydrate gypsum;

[0077] When the green grouting material for rapid repair of bridge cracks based on modified ceramic powder is mixed with mixing water to prepare the grouting slurry, the water-cement ratio is 0.26.

[0078] The preparation method of green grouting material for rapid repair of bridge cracks based on modified ceramic powder includes the following steps:

[0079] S1. Waste ceramics are ground and classified to obtain ceramic core powder, wherein the particle size distribution of the ceramic core powder satisfies D50 of 3-12μm and D90≤35μm;

[0080] S2. Mix the ceramic core powder obtained in step S1 with water to form a slurry with a solid content of 15 wt.%.

[0081] S3. Add calcium-containing components and silicon-containing components to the slurry and stir to react, so that an inorganic reaction shell layer is formed on the surface of the ceramic core powder to obtain system A, wherein the calcium-containing component is calcium oxide and the silicon-containing component is silica sol;

[0082] S4. Add an aluminum-containing component to system A and stir to react, to obtain system B, wherein the aluminum-containing component is sodium aluminate;

[0083] S5. Add a sulfate source to system B and mix and react to obtain system C. The sulfate source is sodium sulfate.

[0084] S6. Solid-liquid separation and drying of system C, followed by deagglomeration and grinding to obtain modified ceramic powder, wherein the thickness of the inorganic reaction shell is 0.05-3.0 μm;

[0085] S7. Ordinary silicate cement, slag powder, sulfoaluminate cement, gypsum and the modified ceramic powder are measured and dry-mixed according to the mass parts to obtain a cementitious material mixture;

[0086] S8. Add polycarboxylate superplasticizer, anti-segregation thickener and defoamer to the cementitious material mixture and mix evenly to obtain green grouting material;

[0087] In step S3, based on the mass of the ceramic core powder, the amount of calcium-containing component added is 8.0 wt.%; the amount of silicon-containing component added is 0.2 wt.% based on the SiO2 solid content.

[0088] In step S4, based on the mass of the ceramic core powder, the amount of aluminum-containing component added is 0.05 wt.% based on the Al2O3 solid content.

[0089] The reaction temperature for steps S3-S5 is 15℃, and the reaction time is 180 min.

[0090] The drying method in step S6 is fluidized bed drying, and the deagglomeration grinding in step S6 is a classifying mill.

[0091] Example 3

[0092] This embodiment provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method, specifically including:

[0093] The green grouting material is a dry mix, including cementitious materials and additives; the cementitious materials are composed of the following components by mass: 35 parts ordinary silicate cement, 18 parts slag powder, 8 parts sulfoaluminate cement, 4 parts gypsum, and 35 parts modified ceramic powder.

[0094] The admixtures, calculated per 100 parts of cementitious material, include: 0.50 parts of polycarboxylate superplasticizer, 0.05 parts of anti-segregation thickener, and 0.04 parts of defoamer;

[0095] The modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reactive shell layer, wherein:

[0096] The ceramic core powder is waste ceramic powder, and the particle size distribution satisfies D50 of 9μm and D90≤35μm;

[0097] The inorganic reaction shell is coated on the surface of the ceramic core powder, and the shell thickness is 1.5 μm;

[0098] The inorganic reaction shell contains a Ca-Si-Al gel phase;

[0099] A sulfate source is added during the preparation of the modified ceramic powder. The sulfate source is a mixture of gypsum and sodium sulfate. The amount of sulfate source added, based on the mass of the ceramic core powder and calculated by solid content, is 4.0 wt.%.

[0100] The specific surface area of ​​the modified ceramic powder is 4.0 m². 2 / g;

[0101] The inorganic reaction shell also includes ettringite crystalline phase and calcium carbonate crystalline phase;

[0102] The gypsum is a mixture of dihydrate gypsum and hemihydrate gypsum;

[0103] When the green grouting material for rapid repair of bridge cracks based on modified ceramic powder is mixed with mixing water to prepare the grouting slurry, the water-cement ratio is 0.30.

[0104] The preparation method of green grouting material for rapid repair of bridge cracks based on modified ceramic powder includes the following steps:

[0105] S1. Waste ceramics are ground and classified to obtain ceramic core powder, wherein the particle size distribution of the ceramic core powder satisfies D50 of 3-12μm and D90≤35μm;

[0106] S2. Mix the ceramic core powder obtained in step S1 with water to form a slurry with a solid content of 30 wt.%;

[0107] S3. Add calcium-containing components and silicon-containing components to the slurry and stir to react, so that an inorganic reaction shell layer is formed on the surface of the ceramic core powder to obtain system A, wherein the calcium-containing component is a mixture of calcium hydroxide and calcium oxide, and the silicon-containing component is a mixture of sodium silicate and silica sol.

[0108] S4. Add aluminum-containing components to system A and stir to react, to obtain system B, wherein the aluminum-containing components are a mixture of aluminate cement and sodium aluminate;

[0109] S5. Add a sulfate source to system B and mix and react to obtain system C. The sulfate source is a mixture of gypsum and sodium sulfate.

[0110] S6. Solid-liquid separation and drying of system C, followed by deagglomeration and grinding to obtain modified ceramic powder, wherein the thickness of the inorganic reaction shell is 0.05-3.0 μm;

[0111] S7. Ordinary silicate cement, slag powder, sulfoaluminate cement, gypsum and the modified ceramic powder are measured and dry-mixed according to the mass parts to obtain a cementitious material mixture;

[0112] S8. Add polycarboxylate superplasticizer, anti-segregation thickener and defoamer to the cementitious material mixture and mix evenly to obtain green grouting material;

[0113] In step S3, based on the mass of the ceramic core powder, the amount of calcium-containing component added is 4.0 wt.%; the amount of silicon-containing component added is 3.0 wt.% based on the SiO2 solid content.

[0114] In step S4, based on the mass of the ceramic core powder, the amount of aluminum-containing component added is 1.5 wt.% based on the Al2O3 solid content.

[0115] The reaction temperature for steps S3-S5 is 40℃, and the reaction time is 90 min.

[0116] The drying method in step S6 is belt drying, and the deagglomeration grinding in step S6 is air jet milling.

[0117] Example 4

[0118] This embodiment provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method, specifically including:

[0119] The green grouting material is a dry mix, including cementitious materials and additives; the cementitious materials are composed of the following components by weight: 40 parts ordinary silicate cement, 15 parts slag powder, 10 parts sulfoaluminate cement, 5 parts gypsum, and 30 parts modified ceramic powder.

[0120] The admixtures, calculated per 100 parts of cementitious material, include: 0.60 parts of polycarboxylate superplasticizer, 0.08 parts of anti-segregation thickener, and 0.06 parts of defoamer;

[0121] The modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reactive shell layer, wherein:

[0122] The ceramic core powder is waste ceramic powder, and the particle size distribution satisfies D50 of 10μm and D90≤35μm;

[0123] The inorganic reaction shell is coated on the surface of the ceramic core powder, and the shell thickness is 2.0 μm;

[0124] The inorganic reaction shell contains a Ca-Si-Al gel phase;

[0125] A sulfate source, gypsum, is added during the preparation of the modified ceramic powder. The amount of sulfate source added, based on the mass of the ceramic core powder and calculated by solid content, is 6.0 wt.%.

[0126] The specific surface area of ​​the modified ceramic powder is 6.0 m². 2 / g;

[0127] The inorganic reaction shell also contains an ettringite crystalline phase;

[0128] The gypsum is hemihydrate gypsum;

[0129] When the green grouting material for rapid repair of bridge cracks based on modified ceramic powder is mixed with mixing water to prepare the grouting slurry, the water-cement ratio is 0.32.

[0130] The preparation method of green grouting material for rapid repair of bridge cracks based on modified ceramic powder includes the following steps:

[0131] S1. Waste ceramics are ground and classified to obtain ceramic core powder, wherein the particle size distribution of the ceramic core powder satisfies D50 of 3-12μm and D90≤35μm;

[0132] S2. Mix the ceramic core powder obtained in step S1 with water to form a slurry with a solid content of 40 wt.%;

[0133] S3. Add calcium-containing components and silicon-containing components to the slurry and stir to react, so that an inorganic reaction shell layer is formed on the surface of the ceramic core powder to obtain system A, wherein the calcium-containing component is calcium hydroxide and the silicon-containing component is silica sol;

[0134] S4. Add aluminum-containing components to system A and stir to react, to obtain system B, wherein the aluminum-containing components are aluminate cement;

[0135] S5. Add a sulfate source to system B and mix and react to obtain system C, wherein the sulfate source is gypsum.

[0136] S6. Solid-liquid separation and drying of system C, followed by deagglomeration and grinding to obtain modified ceramic powder, wherein the thickness of the inorganic reaction shell is 0.05-3.0 μm;

[0137] S7. Ordinary silicate cement, slag powder, sulfoaluminate cement, gypsum and the modified ceramic powder are measured and dry-mixed according to the mass parts to obtain a cementitious material mixture;

[0138] S8. Add polycarboxylate superplasticizer, anti-segregation thickener and defoamer to the cementitious material mixture and mix evenly to obtain green grouting material;

[0139] In step S3, based on the mass of the ceramic core powder, the amount of calcium-containing component added is 6.0 wt.%; the amount of silicon-containing component added is 4.0 wt.% based on the SiO2 solid content.

[0140] In step S4, based on the mass of the ceramic core powder, the amount of aluminum-containing component added is 2.0 wt.% based on the Al2O3 solid content.

[0141] The reaction temperature for steps S3-S5 is 50℃, and the reaction time is 60 min.

[0142] The drying method in step S6 is spray drying, and the deagglomeration grinding in step S6 is a classifying mill.

[0143] Comparative Example 1

[0144] This comparative example provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method. The difference between this example and Example 1 is that the ceramic core powder is not subjected to core-shell modification treatment, and no calcium-containing components, silicon-containing components, aluminum-containing components, or sulfate sources are added during the preparation of the modified ceramic powder. Specifically, S3, S4, and S5 are not performed during the preparation of the modified ceramic powder, while other process parameters and operating conditions are exactly the same as in Example 1.

[0145] Comparative Example 2

[0146] This comparative example provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method. The difference between this example and Example 1 is that no sulfate source is added during the preparation of the modified ceramic powder. Specifically, no sulfate source is added in step S5, while other process parameters and operating conditions are exactly the same as in Example 1.

[0147] Comparative Example 3

[0148] This comparative example provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and its preparation method. The difference between this example and Example 1 is that no aluminum-containing components are added during the preparation of the modified ceramic powder. Specifically, step S4 is not performed, that is, no aluminum-containing components are added in step S4. Other process parameters and operating conditions are exactly the same as in Example 1.

[0149] The objects of the various effects and performance tests of this invention are the green grouting materials prepared in Examples 1-4 and Comparative Examples 1-3, which are mixed with mixing water to form a grout, and then solidified grouting bodies obtained by molding and completing the specified curing, and / or grouting repair bodies formed by injecting the grout into existing precast concrete cracks and curing them.

[0150] The compressive strength was tested in accordance with the "Standard for Test Methods of Mechanical Properties of Ordinary Concrete" GB / T 50081;

[0151] The interfacial bond strength was tested in accordance with the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T 70-2009;

[0152] The impermeability was tested in accordance with the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T 70-2009.

[0153] The test results are shown in Table 1.

[0154] Table 1. Test results of green grouting materials for rapid repair of bridge cracks based on modified ceramic powder in Examples 1-4 and Comparative Examples 1-3.

[0155] Compressive strength (MPa) Interfacial bond strength (MPa) Permeability pressure (MPa) Example 1 63.4 2.5 1.65 Example 2 65.2 2.4 1.60 Example 3 67.6 2.2 1.70 Example 4 64.5 2.6 1.75 Comparative Example 1 56.7 1.6 1.05 Comparative Example 2 59.3 1.9 1.20 Comparative Example 3 57.8 1.8 1.15 surface

[0156] As shown in Table 1, compared with Example 1, the compressive strength, interfacial bond strength and impermeability pressure of Comparative Example 1 decreased; the compressive strength, interfacial bond strength and impermeability pressure of Comparative Example 2 decreased; and the compressive strength, interfacial bond strength and impermeability pressure of Comparative Example 3 decreased.

[0157] This is because Comparative Example 1 did not construct a core-shell inorganic reaction shell, and the ceramic powder surface lacked a calcium-containing silica-alumina gel phase as a heterogeneous nucleation and deposition substrate. The continuous growth of hydration products near the ceramic particles was limited, and discontinuous regions and interconnected pore channels easily formed at the interface, leading to reduced interfacial bonding strength, decreased densification of the solidified body, reduced impermeability pressure, and reduced compressive strength. Comparative Example 2 did not introduce a sulfate source, and the insufficient early sulfate supply altered the formation pathway and distribution of aluminate-related hydration phases, weakening the bridging and pore-filling capacity of hydration products between the shell and the matrix. Simultaneously, insufficient local ionic strength and flocculation state control reduced slurry stability and microstructure uniformity, making it easier for interconnected permeation channels to form in the interfacial region and pore structure. Therefore, interfacial bonding strength, impermeability pressure, and compressive strength all decreased. In Comparative Example 3, without the addition of aluminum-containing components, it is difficult to form an aluminum-involved calcium-silica-alumina gel network in the shell. The shell structure is closer to a single calcium-silica hydration gel phase, with reduced cross-linking and coordination structures. The interfacial reaction layer's ability to induce subsequent hydration product deposition and network connectivity is weakened. At the same time, the lack of aluminum source participation restricts the formation of sulfate-related hydration phases, reduces pore filling and interfacial continuity, resulting in reduced interfacial bonding strength. The reduced density of the cured body leads to a decrease in impermeability pressure and compressive strength.

[0158] The above description is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Those skilled in the art should understand that any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention fall within the protection and disclosure scope of the present invention.

Claims

1. A green grouting material for rapid repair of bridge cracks based on modified ceramic powder, characterized in that, The green grouting material is a dry mix, comprising cementitious materials and admixtures. The cementitious material, by weight, consists of the following components: 25-45 parts ordinary Portland cement, 5-25 parts slag powder, 3-15 parts sulfoaluminate cement, 1-6 parts gypsum, and 20-45 parts modified ceramic powder, with the sum of the weight parts of all components being 100 parts. The admixtures, based on 100 parts of cementitious material, include: 0.20-0.80 parts polycarboxylate superplasticizer, and anti-segregation agent. Thickener 0.01-0.10 parts, defoamer 0.005-0.08 parts; the modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reaction shell layer, wherein: the ceramic core powder is waste ceramic powder; the inorganic reaction shell layer coats the surface of the ceramic core powder; the inorganic reaction shell layer comprises a Ca-Si-Al gel phase; a sulfate source is added during the preparation of the modified ceramic powder, the sulfate source being gypsum and / or sodium sulfate.

2. The green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 1, characterized in that, The modified ceramic powder has a specific surface area of ​​1.5-8.0 m². 2 / g, wherein the particle size distribution of the waste ceramic powder satisfies D50 of 3-12μm and D90≤35μm, and the thickness of the inorganic reaction shell is 0.05-3.0μm.

3. The green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 1, characterized in that, The inorganic reaction shell also contains ettringite crystal phase and / or calcium carbonate crystal phase, and the sulfate source is added in an amount of 0.2-8.0 wt.% based on the mass of the ceramic core powder and the solid content.

4. The green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 1, characterized in that, The gypsum is dihydrate gypsum and / or hemihydrate gypsum.

5. The green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 1, characterized in that, When the green grouting material for rapid repair of bridge cracks based on modified ceramic powder is mixed with mixing water to prepare the grouting slurry, the water-cement ratio is 0.26-0.

36.

6. A method for preparing a green grouting material for rapid repair of bridge cracks based on modified ceramic powder as described in any one of claims 1-5, characterized in that, The process includes the following steps: S1, grinding and classifying waste ceramics to obtain ceramic core powder; S2, mixing the ceramic core powder with water to form a slurry; S3, adding a calcium-containing component and a silicon-containing component to the slurry and stirring to react, so that an inorganic reaction shell layer is formed on the surface of the ceramic core powder to obtain system A, wherein the calcium-containing component is calcium hydroxide and / or calcium oxide, and the silicon-containing component is sodium silicate and / or silica sol; S4, adding an aluminum-containing component to system A and stirring to react to obtain system B, wherein the aluminum-containing component is aluminate cement and / or sodium aluminate; S5, adding a sulfate source to system B and mixing to react to obtain system C; S6, performing solid-liquid separation and drying on system C, and then deagglomerating and grinding to obtain modified ceramic powder; S7. Weigh and dry mix ordinary silicate cement, slag powder, sulfoaluminate cement, gypsum and the modified ceramic powder according to the mass fractions specified in claim 1 to obtain a cementitious material mixture; S8. Add polycarboxylate superplasticizer, anti-segregation thickener and defoamer to the cementitious material mixture and mix evenly to obtain a green grouting material.

7. The preparation method of the green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 6, characterized in that, In S2, the solid content of the slurry is 15-45 wt.%, and in S3, based on the mass of the ceramic core powder, the amount of calcium-containing component added is 0.5-8.0 wt.%, and the amount of silicon-containing component added is 0.2-6.0 wt.% based on the SiO2 solid content.

8. The preparation method of the green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 6, characterized in that, Based on the mass of the ceramic core powder in S4, the amount of aluminum-containing component added is 0.05-3.0 wt.% according to the Al2O3 solid content.

9. The preparation method of the green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 6, characterized in that, In S3-S5, the reaction temperature is 15-60℃ and the reaction time is 10-180min.

10. The preparation method of the green grouting material for rapid repair of bridge cracks based on modified ceramic powder according to claim 6, characterized in that, In S6, the drying method is one of spray drying, fluidized bed drying or belt drying, and the deagglomeration grinding is air jet milling or classifying milling.

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