Green grouting material for rapidly repairing bridge cracks based on modified ceramic powder and preparation method of green grouting material

Abstract

The invention 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 of the green grouting material. The grouting material is a dry mixture, ordinary Portland cement, slag powder, sulphoaluminate cement, gypsum and modified ceramic powder form a gelling system, and the gelling system is matched with a polycarboxylic acid water reducing agent, an anti-segregation thickening agent and a defoaming agent. The modified ceramic powder is of a core-shell composite structure, a ceramic core is obtained by grinding and grading waste ceramic, an inorganic reaction shell layer is generated in situ under a slurry condition, the shell layer contains a calcium-silicon-aluminum gel phase, and a sulfate source is introduced in the preparation process; the preparation method comprises the following steps: preparing ceramic core slurry, adding calcium-containing and silicon-containing components to form a shell layer, adding an aluminum-containing component to regulate and control the composition of the shell layer, adding a sulfate source, carrying out solid-liquid separation and drying, depolymerizing and grinding to obtain modified ceramic powder, then carrying out dry mixing on the modified ceramic powder and each gelling component, and adding an additive to obtain the grouting material.

Description

TECHNICAL FIELD

[0001] The application 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 a preparation method thereof. BACKGROUND

[0002] During the service of a bridge, different forms of cracks are prone to occur in concrete components under the action of environmental factors such as vehicle load, temperature gradient, dry-wet cycle and freeze-thaw. Once the cracks are connected or connected with the outside world, water and chloride ions and other media will enter, which will accelerate the corrosion of steel bars and the deterioration of the interface, and then cause problems such as spalling, leakage and durability decline. In order to restore the integrity of the component and block the erosion channel, pressure grouting and other methods are often used to repair the cracks. The grouting material needs to consider the injectability, stability and performance after hardening: it not only needs to smoothly penetrate into small cracks and maintain continuous flow, but also needs to avoid bleeding, segregation and settlement during the injection process, and the hardened body should also have mechanical and volume stability characteristics compatible with the existing concrete to reduce the risk of re-cracking after repair.

[0003] The existing crack grouting system mainly includes epoxy, organic acrylate and cement-based inorganic materials. Epoxy and acrylate grouting materials usually have good permeability and adhesion, but have problems such as high cost, strong construction sensitivity, limited adaptability to wet interfaces, and some systems may bring volatility or safety management requirements. Cement-based grouting materials have wide raw material sources, good durability and strong compatibility with concrete, and are widely used in engineering, but they still face the contradiction between particle size and rheological control in the injection of micro-cracks, and the common system often has problems such as insufficient flow retention, difficult segregation and bleeding control, and early volume change leading to interface micro-cracks under low water-binder ratio conditions.

[0004] In order to improve the above problems, the existing technology usually optimizes by using micro-cement, complexly mixing mineral admixtures, introducing early strength or expansion components, using polycarboxylic acid water reducer and thickener, etc. However, simply relying on external agent regulation or conventional admixture replacement often cannot simultaneously meet the requirements of injectability, segregation resistance and early structure formation. In addition, although the resource utilization of waste ceramics and other solid wastes in cement-based materials has environmental and cost advantages, the powder of waste ceramics is usually irregular and has strong interface inertia, which may cause problems such as flowability reduction, insufficient particle dispersion and interface transition zone weakening when directly used as an admixture, thereby limiting its application in crack grouting materials. SUMMARY

[0005] In view of the deficiencies of the prior art, the purpose of the present application is to provide a green grouting material for rapid repair of bridge cracks based on modified ceramic powder and a preparation method thereof, which is a dry mixing system and is composed of cement, slag powder, sulphoaluminate cement, gypsum and a core-shell structure modified ceramic powder to form a cementing system, and is matched with water reducing, thickening and defoaming additives. The modified ceramic powder is obtained by grinding and grading waste ceramic powder to obtain ceramic core powder, in-situ generating an inorganic reaction shell containing calcium-silicon-aluminum gel phase under slurry conditions and introducing a sulfate source, and then obtaining by solid-liquid separation, drying and depolymerization grinding, and then dry mixing to obtain the grouting material, thereby meeting the needs of actual production.

[0006] To achieve this purpose, the present application adopts the following technical solutions:

[0007] In a first aspect, the present application provides a green grouting material for rapid repair of bridge cracks based on modified ceramic powder, which is a dry mixing material and comprises cementing material and additive; the cementing material consists of the following components by mass fraction: ordinary Portland cement 25-45 parts, slag powder 5-25 parts, sulphoaluminate cement 3-15 parts, gypsum 1-6 parts, and modified ceramic powder 20-45 parts, and the sum of the mass fractions of the components of the cementing material is 100 parts;

[0008] The additive comprises, based on 100 parts of cementing material: polycarboxylic acid water reducing agent 0.20-0.80 parts, anti-segregation thickening agent 0.01-0.10 parts, and defoaming agent 0.005-0.08 parts;

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

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

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

[0012] The inorganic reaction shell comprises 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, and the addition amount of the sulfate source is 0.2-8.0 wt.% based on the mass of the ceramic core powder as solid content.

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

[0015] Preferably, the inorganic reaction shell further comprises ettringite crystal phase and / or calcium carbonate crystal 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 water to obtain a grouting slurry, the water-binder ratio is 0.26-0.36.

[0018] In a second aspect, the present application provides a preparation method of the green grouting material for rapid repair of bridge cracks based on modified ceramic powder, comprising the following steps:

[0019] S1, grinding and classifying waste ceramic to obtain ceramic core powder, wherein the particle size distribution of the ceramic core powder satisfies D50 of 3-12 μm and D90≤35 μm;

[0020] S2, mixing the ceramic core powder with water to form a slurry;

[0021] S3, adding a calcium-containing component and a silicon-containing component to the slurry and stirring to form an inorganic reaction shell 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;

[0022] S4, adding an aluminum-containing component to system A and stirring to obtain system B, wherein the aluminum-containing component is aluminate cement and / or sodium aluminate;

[0023] S5, adding a sulfate source to system B and mixing to obtain system C, wherein the sulfate source is gypsum and / or sodium sulfate;

[0024] S6, performing solid-liquid separation and drying on system C, and performing deagglomeration and grinding to obtain modified ceramic powder;

[0025] S7, weighing and dry mixing ordinary Portland cement, slag powder, sulphoaluminate cement, gypsum and the modified ceramic powder according to the mass parts in claim 1 to obtain a cementitious material mixture;

[0026] S8, adding polycarboxylate superplasticizer, anti-segregation thickener and defoaming agent to the cementitious material mixture and mixing uniformly to obtain the green grouting material.

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

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

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

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

[0031] In the preparation of the modified ceramic powder, the surface of the waste ceramic powder is mainly composed of silicon-oxygen and aluminum-oxygen frameworks, and there are hydroxylated sites and defect sites on the surface. The calcium-containing component undergoes hydration and dissociation after entering the aqueous phase, providing calcium ions and a high-alkalinity environment; the silicon-containing component exists in the form of soluble silicate or silicic acid alcohol condensation precursor under alkaline conditions. Calcium ions and silicate undergo heterogeneous nucleation and deposition at the solid-liquid interface, and a calcium-silicon hydrate gel phase is preferentially generated on the surface of the ceramic particles; when the aluminum-containing component is added, aluminate or aluminate hydrate participates in the coordination and polymerization of the gel network, forming a calcium-silicon-aluminum hydrate gel phase, and the deposition layer changes from a single calcium-silicon hydrate network to an aluminum-containing cross-linked network. Since the reaction occurs on the surface of the ceramic particles, the deposition layer and the ceramic substrate are chemically connected through the condensation of surface hydroxyl groups of the silicon-oxygen framework, calcium bridge coordination, and local corrosion and redeposition processes, so that the shell layer no longer behaves as a simple physical covering, but as a continuous inorganic phase generated by interfacial reaction. After the introduction of a sulfate source, a calcium aluminate hydrate phase containing sulfate is formed in the local environment where calcium ions and aluminate coexist, and part of it is precipitated in the form of ettringite crystal phase and coexists with the gel phase; sulfate can also exist in the form of ions in the gel pores and surface adsorption layer, forming a migratory sulfate reservoir. After solid-liquid separation, drying, and deagglomeration grinding, the obtained powder maintains a core-shell structure: the inner core is a ceramic particle, and the outer layer is a composite shell of a calcium-silicon-aluminum gel phase and a sulfate-containing aluminate hydrate phase.

[0032] When the green grouting material is contacted with mixed water, the ordinary portland cement mineral phase dissolves to release calcium ions, hydroxyl ions and silicate ions, the sulphoaluminate cement dissolves to release aluminate ions, calcium ions and generates ettringite in the presence of sulfate ions, and the slag powder undergoes potential hydration under the action of alkalinity and calcium source and forms an aluminum-containing calcium-silicon hydrated gel phase. The role of the modified ceramic powder in the system is interface hydration connection and local ion regulation. The shell layer itself contains a calcium-silicon-aluminum gel phase, which can act as a heterogeneous nucleation substrate for the deposition of hydration products; the calcium-silicon hydrated gel and the aluminum-containing gel generated during the hydration process of cement and slag continue to deposit on the surface of the shell layer and form a gel network that penetrates each other, forming a continuous inorganic phase connection between the ceramic particles and the matrix hydration products, and the interface does not need to rely on physical interlocking to transfer stress and block channels. The sulfate ions introduced in the shell layer react with calcium ions and aluminate ions in the solution during the early hydration of the aluminate hydration phase, generating ettringite and growing in the pore space, accompanied by changes in the ionic strength of the solution and adjustments in the volume distribution of the hydration products; this process changes the bridging and flocculation state between particles in the slurry and works together with the anti-segregation thickening agent to limit the migration of free water and the settlement of solid phase. The polycarboxylic acid-based water reducing agent is complexed with calcium ions through carboxyl groups and adsorbed on the surface of the solid phase in the early hydration stage, providing steric hindrance dispersion; the calcium-silicon-aluminum gel phase and the surface hydroxyl sites of the modified shell layer participate in the adsorption equilibrium of the water reducing agent, allowing the water reducing agent to establish a repeatable adsorption and desorption process between the ceramic powder and the cement particles, thereby affecting the particle dispersion state and flow retention. The defoaming agent changes the gas-liquid interfacial tension and promotes the coalescence and escape of gas bubbles, reducing the pore volume occupied by gas bubbles in the slurry, and finally forming a multi-phase solidified structure composed of calcium-silicon-aluminum gel phase, ettringite phase and unreacted ceramic core.

[0033] Compared with the prior art, the green grouting material of the present application adopts a core-shell structure modified ceramic powder and cement, slag powder, sulphoaluminate cement and gypsum to form a composite cementitious system. The inorganic reaction shell layer of the modified powder acts as a heterogeneous nucleation and deposition interface during the hydration process of the material, allowing the hydration products to grow continuously on the surface of the ceramic particles and penetrate the matrix gel network, reducing the interface discontinuity between the ceramic particles and the cement stone, and reducing the formation of penetration channels at the interface. The sulfate source introduced in the shell layer cooperates with the aluminate hydration reaction phase to adjust the early ion environment and hydration phase generation path, and cooperates with the thickening system to inhibit the bleeding of the slurry and the settlement of the particles, which is beneficial to the stable delivery and filling during the grouting process; the modified ceramic powder is derived from the resource utilization of waste ceramic, reducing the consumption of natural mineral admixtures and the pressure of solid waste storage, and the material system is an inorganic cementitious system, which is suitable for the durability requirements of bridge crack repair scenes. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The SEM image of the microstructure of the grouting material after hydration and hardening of Example 1 of the present application;

[0035] Figure 2 This is a SEM image of the microstructure 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 This is a SEM image of the microstructure of the grouting material after hydration and hardening, provided in this embodiment. Figure 2 The image shows the microstructure of the contact area between the grouting material and the matrix 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) Permeation resistance 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

[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 is composed of the following components by mass: 25-45 parts of ordinary Portland 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, and the sum of the mass parts of each component of the cementitious material is 100 parts. 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; The modified ceramic powder is a core-shell composite powder, comprising a ceramic core powder and an inorganic reactive shell layer, wherein: The ceramic core powder is waste ceramic powder; The inorganic reaction shell layer is coated on the surface of the ceramic core powder; The inorganic reaction shell contains a Ca-Si-Al gel phase; A sulfate source is added during the preparation of the modified ceramic powder, wherein the sulfate source is 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, Includes the following steps: S1. Waste ceramics are ground and classified to obtain ceramic core powder; S2. Mix the ceramic core powder with water to form a slurry; 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. 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. S5. Add sulfate source to system B and mix and react to obtain system C; S6. Solid-liquid separation and drying of system C, followed by deagglomeration 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 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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