A multi-stage release self-healing material, its preparation method and application

Abstract

This invention provides a multi-stage release self-healing material, its preparation method, and its application, belonging to the field of building materials technology. Through ingenious structural design, this invention combines solid waste resource utilization, material multifunctionality, and intelligent concrete maintenance to prepare a multi-stage release self-healing material. This multi-stage release self-healing material has a multi-layered spherical core-shell structure, comprising, from the inside out: a solid waste core layer, an inner self-healing layer, an intermediate barrier protective layer, an outer self-healing layer, and an activating functional protective layer. The self-healing material can be directly used as a functional aggregate during the concrete mixing stage. It exhibits good compatibility with concrete and can respond on demand and release repair agents in stages, achieving intelligent, efficient, and durable self-repair of concrete cracks. This provides an innovative, efficient, and green solution for improving the durability and safety of major infrastructure projects.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a multi-stage release self-healing material, its preparation method, and its application. Background Technology

[0002] Concrete, as one of the most widely used materials in modern construction, inevitably develops cracks during long-term service. These cracks not only affect the durability and aesthetics of building structures but also provide pathways for the intrusion of harmful media such as moisture, chloride ions, and carbon dioxide, accelerating the corrosion of internal steel reinforcement, leading to a decrease in structural load-bearing capacity, and ultimately shortening the lifespan of buildings. Therefore, developing self-healing technologies capable of automatically repairing concrete cracks has become a key research direction for improving concrete durability, achieving longer material lifespans, and promoting sustainable development.

[0003] Currently, common self-healing technologies mainly include: utilizing the continued hydration, crystallization and precipitation of unhydrated particles in the cement matrix, microbial-induced mineralization, and pre-placed repair agents (such as microcapsules, fiber tubes, and microvessels). Among these, the pre-placed repair agent method has attracted much attention due to its high healing efficiency and clear target. Microcapsule technology encapsulates a repair agent (such as epoxy resin or sodium silicate solution) in a polymer shell. When the crack propagates and causes the capsule to rupture, the repair agent flows out and solidifies to achieve repair. For example, patent CN113045283A provides a smart trigger-type self-healing microcapsule for microcracks in concrete, which releases the repair agent through capsule rupture. However, this approach has two key problems: First, the microcapsule wall material uses organic materials such as ethyl cellulose and chitosan, which have poor chemical compatibility with the cement matrix and cannot participate in the hydration reaction. This may form a weak interface in the concrete, thus affecting its mechanical properties. Second, due to the aforementioned compatibility issues, the dosage of the microcapsules in the concrete must be strictly controlled at a low level. This directly results in a limited total amount of effective repair components in the entire system, making it difficult to achieve a sufficient and reliable repair effect on dispersed or large-scale cracks.

[0004] It is evident that traditional microcapsules or repair carriers are typically designed for single-trigger, one-time release, which has significant limitations: First, once the repair agent is released, the affected area loses its subsequent repair capacity, making it unable to cope with potential re-cracking at the same location; second, different sizes and stages of crack development require different types and dosages of repair agents, and a single large release may result in waste or poor repair effectiveness; third, for deep or time-progressing cracks, a single release is insufficient for achieving continuous and deep effective repair. Furthermore, existing self-healing systems have relatively limited functionality, primarily focusing on the physical sealing of cracks, lacking multi-functional synergy such as strengthening the surrounding matrix and continuously improving impermeability. Additionally, some repair agents (such as some organic resins) have insufficient compatibility with the alkaline environment of concrete or exhibit poor long-term stability.

[0005] Therefore, there is an urgent need in this field for a novel self-healing carrier capable of responding to crack development in a phased and intelligent manner. An ideal self-healing particle should possess the following capabilities: 1) It should be able to trigger the graded and sequential release of different repair agents based on the width, depth, or stage of crack propagation, achieving precise repair; 2) It should possess multiple repair potential, improving the utilization efficiency of repair resources and the durability of the repair; 3) While releasing the repair agent, it should be well-compatible with the concrete matrix and may bring additional performance gains (such as reinforcement and corrosion protection). Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a multi-stage release self-healing material, its preparation method, and its applications. Through a unique structural design, this invention enables the on-demand, staged release of the self-healing material at different stages of crack initiation and propagation, significantly enhancing the intelligent, efficient, and durable self-repair capabilities of concrete cracks. It also holds promise for expanding the application prospects of self-healing materials in harsh environments, solving the technical problems of existing self-healing materials' inability to achieve multiple, time-controlled repair responses and their failure to be efficiently integrated with the resource utilization of large quantities of solid waste.

[0007] To achieve the above objectives, the specific technical solution of the present invention is as follows:

[0008] In a first aspect, the present invention provides a multi-level release self-healing material having a multi-layer spherical core-shell structure, comprising, from the inside out: a solid waste core layer, an inner self-healing layer, an intermediate barrier protective layer, an outer self-healing layer, and an excitable functional protective layer.

[0009] The raw materials for the solid waste core layer include: 90-80 parts of lithium slag-based solid waste material and 10-20 parts of filler.

[0010] The raw materials of the inner self-healing layer include: 20-25 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 15-20 parts of ethylenediaminetetraacetic acid, 10-15 parts of metakaolin, 8-12 parts of polybasic organic acids, and 3-5 parts of sodium fluorosilicate.

[0011] The raw materials for the intermediate barrier protective layer include: 50-80 parts of lithium slag ultrafine powder, 15-20 parts of anhydrous gypsum, and 10-15 parts of sodium-based bentonite.

[0012] The raw materials of the external self-healing layer include: 20-25 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 15-25 parts of nano calcium carbonate, 12-16 parts of sodium aluminate, 10-15 parts of nano silica, and 3-5 parts of sodium tripolyphosphate.

[0013] The raw materials for the activating functional protective layer include: 35-45 parts calcium hydroxide, 25-35 parts sodium fluorosilicate, 15-25 parts stone powder, 1-3 parts redispersible polymer powder, and 1-3 parts stearate.

[0014] Furthermore, the diameter of the multi-stage release self-healing material is 20-30 mm. The thickness or diameter range of each layer can be fine-tuned according to the actual application scenario (such as building concrete, mortar, waterproofing projects, etc.). After fine-tuning, the following mass ratio must be met: solid waste core layer, inner self-healing layer, intermediate barrier protective layer, outer self-healing layer, and activating functional protective layer: (4-6):(23-27):(13-17):(33-37):(18-22). This ratio ensures structural stability, sufficient repair material reserves, and reasonable release kinetics. The thickness of each layer must ensure the realization of its corresponding function (the core layer provides active components, the self-healing layer provides repair capabilities, the protective layer provides strength and stability, and the activating layer triggers release). At the same time, the thickness deviation of each layer should be controlled within ±0.2 mm to ensure the uniformity and stability of the multi-layer core-shell structure and avoid functional failure due to uneven thickness.

[0015] Furthermore, the solid waste core layer is a solid sphere with a diameter of 3-4 mm. The solid waste core layer uses lithium slag-based solid waste materials (such as spodumene slag and lepidolite slag) as the core and active carrier. These materials are rich in amorphous aluminosilicates, which can slowly participate in the pozzolanic reaction in an alkaline environment. However, because the core layer is tightly isolated by the inner and outer layers, it remains inert during concrete curing. Therefore, it is prepared in conjunction with appropriate fillers (such as fly ash and silica fume). The fillers are used to adjust the bulk density and mechanical strength of the solid waste core layer, preventing it from becoming too loose. Fly ash and silica fume provide a micro-aggregate filling effect, while stone powder acts as an inert diluent, ensuring the core layer maintains its spherical integrity during granulation and curing. The particle size design of the solid waste core layer considers both the resource utilization of solid waste and the feasibility of subsequent multi-layer coating, avoiding agglomeration due to excessively small particle size and difficulty in achieving uniform multi-layer coating due to excessively large particle size.

[0016] Furthermore, the lithium slag-based solid waste material includes, but is not limited to, at least one of spodumene slag and lepidolite slag. Specifically, the lepidolite slag, before being used to prepare the solid waste core layer, needs to undergo defluorination treatment (thermal activation at 500-600 °C to achieve defluorination) to eliminate the adverse effects of fluorides on cement hydration.

[0017] Furthermore, the filler includes, but is not limited to, at least one of fly ash, silica fume, and stone powder.

[0018] Furthermore, the internal self-healing layer covers the outer side of the solid waste core layer, and the thickness of the internal self-healing layer is 5-8 mm. The internal self-healing layer is the core functional layer that exerts the self-healing effect. The medium-dissolving sodium silicate gradually dissolves after cracks appear, releasing silicate ions, which react with calcium ions in the cement pore liquid to form CSH gel and calcium silicate precipitate, sealing the cracks. The high modulus of sodium silicate ensures a moderate dissolution rate, avoiding premature release. Ethylenediaminetetraacetic acid (such as disodium ethylenediaminetetraacetate) acts as a chelating agent, chelating calcium, aluminum, and other metal ions in the system, preventing the internal self-healing layer from prematurely gelling or precipitating due to accidental contact with moisture during storage or concrete mixing, significantly extending the material's shelf life. The material's shelf life is considered. Metakaolin is an active aluminosilicate mineral that can be activated in an alkaline environment to generate geopolymer gel, assisting sodium silicate in forming a denser healing product. It also regulates the slurry's rheology, facilitating granulation. Multi-element organic acids (such as fumaric acid) regulate the system's pH and reaction rate, preventing premature curing of the inner layer. Sodium fluorosilicate, as a potential activator for the inner layer, reacts with calcium hydroxide in the cement after crack initiation, generating loose calcium fluoride and soluble sodium silicate. Sodium silicate replenishes the self-healing agent, while calcium fluoride loosens the inner layer structure, promoting outward diffusion of the healing agent. The thickness design of the inner self-healing layer meets the release requirements of the self-healing material during crack repair, while ensuring dense coverage, avoiding premature breakage due to excessive thinness and affecting the coverage effect of subsequent layers due to excessive thickness.

[0019] Furthermore, the ethylenediaminetetraacetic acid salt includes, but is not limited to, at least one of disodium ethylenediaminetetraacetate and tetrasodium ethylenediaminetetraacetate.

[0020] Furthermore, the polybasic organic acids include, but are not limited to, at least one of fumaric acid, citric acid, and succinic acid.

[0021] Furthermore, the intermediate barrier protective layer covers the outside of the inner self-healing layer, and the thickness of the intermediate barrier protective layer is 3-5 mm. The intermediate barrier protective layer is composed of lithium slag ultrafine powder, anhydrous gypsum, and sodium-based bentonite, which endows the material with mechanical strength and environmental stability. In the early stages of concrete mixing and curing, this layer forms a dense waterproof layer through the formation of ettringite and the expansion of bentonite, preventing moisture from entering the inner layer. However, after cracks appear, with the continuous action of moisture, the ettringite gradually dissolves, and the repeated expansion and contraction of bentonite causes micro-cracks in the barrier layer, resulting in the barrier layer losing its sealing properties and releasing the inner self-healing material, thus achieving a delayed-trigger multi-stage release effect. The thickness design of the intermediate barrier protective layer needs to balance mechanical protection performance and overall particle size control to ensure effective protection of the inner self-healing material while avoiding excessive thickness that would increase the overall weight.

[0022] Furthermore, the outer self-healing layer covers the outside of the intermediate barrier protective layer, and the thickness of the outer self-healing layer is 6-10 mm. The raw materials of the outer self-healing layer differ from those of the inner self-healing layer. The raw materials of the outer self-healing layer include: fast-dissolving sodium silicate, nano-calcium carbonate, sodium aluminate, nano-silica, and sodium tripolyphosphate. The fast-dissolving sodium silicate dissolves rapidly after cracks appear, reacting with calcium ions to form CSH gel, achieving early and rapid crack filling. Its lower modulus contributes to higher alkalinity and faster dissolution. Nano-calcium carbonate provides a nano-scale calcium source, reacting with sodium silicate to form a nano-calcium carbonate-calcium silicate composite precipitate, improving the density of the healing product and its adhesion to the matrix. Simultaneously, the nanoparticles can fill microcracks. Sodium aluminate, as a strongly alkaline aluminum source, rapidly dissociates into [Al(OH)4] upon contact with water. - It reacts with sodium silicate to form geopolymer gel (NASH) and with calcium ions to form CASH, enhancing the mechanical properties and durability of the healing product; nano silica is a highly active nanofiller that dissolves rapidly in an alkaline environment and participates in condensation reaction, promoting the formation of dense calcium silicate / aluminosilicate gel, while filling pores and improving the strength and impermeability of the healing area; sodium tripolyphosphate acts as a retarder and dispersant, delaying the premature gelation of the outer self-healing material due to contact with a small amount of water during concrete mixing, while dispersing nanoparticles to prevent agglomeration and ensure uniform granulation.

[0023] Furthermore, the activating functional protective layer covers the outer side of the outer self-healing layer, and the thickness of the activating functional protective layer is 2-3 mm. As both an outer protective and activation layer, the thickness design of the activating functional protective layer must consider activation efficiency, environmental tolerance, and mechanical protection. This invention, by introducing activating components (such as sodium fluorosilicate and calcium hydroxide), ensures that the multi-stage release self-healing material ultimately prepared by this invention can be triggered and released under external stimuli (such as stress generated by cracks), while simultaneously resisting external environmental erosion (such as moisture and chloride ions), thus extending the material's service life.

[0024] The calcium hydroxide in the activating functional protective layer provides an alkaline environment and calcium source, reacting with sodium fluorosilicate: Na₂SiF₆ + 3Ca(OH)₂ → 3CaF₂ + Na₂SiO₃ + 3H₂O generates loose calcium fluoride crystals and soluble sodium silicate, leading to the disintegration of the protective layer structure. Simultaneously, calcium hydroxide itself is slightly soluble in water and gradually dissolves upon contact with water, further weakening the protective layer's strength. Sodium fluorosilicate is a key activator, reacting with calcium hydroxide under alkaline conditions to produce a disintegration effect. The resulting calcium fluoride lacks binding properties, causing the protective layer to crumble, while the generated sodium silicate can act as a supplementary self-healing agent, entering cracks and participating in the healing reaction. Stone powder (100-200 mesh) acts as an inert filler, adjusting the mechanical properties and brittleness of the protective layer, providing a volumetric skeleton, preventing premature damage during concrete mixing, and controlling the reaction rate to avoid excessive disintegration. Redispersible adhesive powder (VAE type) enhances the cohesion and adhesion to the inner layer of the protective layer, ensuring its integrity during concrete mixing and curing. Upon contact with water, the adhesive powder forms a polymer film with a certain degree of flexibility, preventing shrinkage cracking. Stearates (such as calcium stearate) act as hydrophobic agents, imparting hydrophobicity to the surface of the protective layer, delaying water penetration during the concrete mixing stage, preventing premature reaction of the protective layer during curing, and acting as a lubricant to facilitate the rolling and forming of particles during the granulation process.

[0025] Furthermore, the stearate includes, but is not limited to, at least one of calcium stearate, zinc stearate, and magnesium stearate.

[0026] Secondly, the present invention provides a method for preparing the multi-stage release self-healing material, comprising the following steps:

[0027] S1. Mixing of raw materials:

[0028] Mix 90-80 parts of lithium slag-based solid waste material and 10-20 parts of filler evenly to obtain solid waste core layer material;

[0029] Mix 20-25 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 15-20 parts of ethylenediaminetetraacetic acid, 10-15 parts of metakaolin, 8-12 parts of polybasic organic acid, and 3-5 parts of sodium fluorosilicate evenly to obtain the inner self-healing layer material.

[0030] Mix 50-80 parts of lithium slag ultrafine powder, 15-20 parts of anhydrous gypsum, and 10-15 parts of sodium-based bentonite evenly to obtain an intermediate barrier protective layer material.

[0031] Mix 20-25 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 15-25 parts of nano-calcium carbonate, 12-16 parts of sodium aluminate, 10-15 parts of nano-silica, and 3-5 parts of sodium tripolyphosphate evenly to obtain an external self-healing layer material.

[0032] Mix 35-45 parts calcium hydroxide, 25-35 parts sodium fluorosilicate, 15-25 parts stone powder, 1-3 parts redispersible polymer powder, and 1-3 parts stearate evenly to obtain an activating functional protective layer material.

[0033] S2, Granulation:

[0034] The solid waste core layer material is spherically granulated while simultaneously spraying in a first atomized water. The granulation time is controlled at 8-10 minutes to form core skeleton spheres with a diameter of 2-5 mm. The solid waste core layer mainly consists of lithium slag-based solid waste material, with a typical water absorption rate of 8%-12%. The atomized water sprayed during granulation must be sufficient to form uniform solid spherical particles while avoiding material powder agglomeration. The amount of the first atomized water sprayed is 10%-15% of the mass of the solid waste core layer material. This amount of water sprayed allows the lithium slag-based solid waste material and filler to be fully wetted and bonded, forming uniform core spherical particles with a diameter of 2-5 mm, which is suitable for subsequent coating processes.

[0035] S3. Preparation of the inner self-healing layer:

[0036] An inner self-healing layer material is added to the core skeleton spheres, and a second spray of atomized water is simultaneously injected. The granulation time is controlled at 6-8 minutes to form a double-layer structure sphere with a diameter of 6-12 mm. The inner self-healing layer mainly consists of active powder, with a water absorption rate slightly higher than that of the solid waste core layer material, approximately 12%-18%. The sprayed atomized water needs to ensure that the inner self-healing layer material is uniformly adhered to the surface of the core skeleton spheres to form a dense coating layer. The amount of the second spray of atomized water is 14%-19% of the mass of the inner self-healing layer material. This amount of water ensures that the inner self-healing layer material is completely wetted and tightly wrapped around the surface of the core skeleton spheres, forming a double-layer structure sphere with a diameter of 6-12 mm, without any shedding or core exposure.

[0037] S4. Preparation of the intermediate barrier protective layer:

[0038] A middle barrier protective layer material is added to the double-layer structured spheres, and a third atomized water is sprayed in simultaneously. The granulation time is controlled at 5-7 minutes to form a three-layer structured sphere with a diameter of 10-18 mm. The middle barrier protective layer is mostly composed of inert fillers with a low water absorption rate of about 6%-10%. The atomized water must ensure that the middle barrier protective layer material is uniformly coated without affecting the stability of the inner layer structure. The amount of the third atomized water sprayed is 7%-11% of the mass of the middle barrier protective layer material. This amount of water spraying can make the middle barrier protective layer material adhere tightly and form a protective layer of uniform thickness on the surface of the double-layer structured spheres, avoiding cracking and peeling, and ensuring the mechanical strength of the three-layer structured spheres.

[0039] S5. Preparation of the external self-healing layer:

[0040] An outer self-healing layer material is added to a three-layer structured sphere, and a fourth atomized water is sprayed simultaneously. The granulation time is controlled at 6-8 minutes to form a four-layer structured sphere with a diameter of 16-26 mm. The outer self-healing layer mainly consists of active powder material with a water absorption rate of approximately 12%-18%. The outer self-healing layer is slightly thicker, requiring more atomized water to be sprayed to ensure uniform and dense coating. The amount of the fourth atomized water sprayed is 15%-20% of the mass of the outer self-healing layer material. This amount of water is sufficient to fully wet and uniformly coat the outer self-healing layer material, forming a four-layer structured sphere with a diameter of 16-26 mm, thus achieving the structural basis for multi-stage release.

[0041] S6. Preparation of the protective layer for stimulating functional activity:

[0042] An activating functional protective layer material is added to a four-layer structured sphere, and a fifth atomized water is sprayed in. The granulation time is controlled to be approximately 7-9 minutes, resulting in a five-layer structured sphere with a diameter of 20-30 mm. The five-layer structured sphere is then covered and moisturized to obtain a multi-stage release self-healing material. The activating functional protective layer contains an activator and inert filler, with a water absorption rate between that of the protective layer and the self-healing layer, approximately 9%-13%. The sprayed atomized water must ensure that the activating functional protective layer is densely coated, while activating the potential activity of the activator and preventing cracking of the outer layer. The amount of the fifth atomized water sprayed is 10%-14% of the mass of the activating functional protective layer material. This amount of water spraying ensures that the outer protective layer is evenly coated, forming a five-layer structured sphere with a diameter of 20-30 mm, ensuring the environmental stability and activating performance of the outer shell layer.

[0043] In the preparation method of the multi-stage release self-healing material, the amount of atomized water injected is an estimated value under conventional processes. Those skilled in the art can make fine adjustments based on the actual granulation equipment (such as disc granulators, spray granulators), ambient humidity (20%~60%), and the actual water absorption rate of each layer of material. The fine adjustment range is controlled within ±0.2 kg. At the same time, the atomized water injected each time is injected intermittently, combined with stirring, to ensure that the material balls are formed uniformly, without sticking or breakage. The moisture content of the final finished material balls is controlled at 8%~12%, which is suitable for subsequent applications of building materials (such as concrete admixture, mortar mixing).

[0044] Furthermore, in step S1, the mixing speed during the process of mixing the raw materials is 20-60 r / min, and the mixing time is 15-30 min.

[0045] Furthermore, in step S6, the duration of the moisturizing and protective covering is ≥ 7 days.

[0046] Thirdly, the present invention provides the application of the multi-stage release self-healing material in the preparation of cement-based building materials (such as concrete), wherein the multi-stage release self-healing material is added to the building material at a dosage of 1% to 2% of the total mass of the gel material.

[0047] The working principle and advantages of the multi-stage release self-healing material described in this invention are as follows:

[0048] The innovative alternating structure of "solid waste core - functional layer - protective layer": This invention achieves "encapsulation" and "controlled release" of the repair components by constructing a five-layer spherical core-shell structure. The outermost activating functional protective layer acts as a physical barrier during concrete mixing and early service stages, preventing premature reaction of the internal active components. When microcracks develop in the concrete and progress to the activating functional protective layer, this layer gradually depletes or breaks down, triggering the release of active components from the self-healing layer it encapsulates. The active components migrate to the cracks with the infiltrated moisture, generating dense healing products such as calcium carbonate and CSH gel through complex chemical reactions, effectively sealing the cracks. The inner and outer self-healing layers enable the multi-stage release self-healing material to respond to cracks of different degrees and stages two or more times, achieving full-cycle intelligent maintenance from early microcrack control to later crack repair.

[0049] Synergistic utilization of solid waste resources and functionalization of materials: The core layer uses industrial solid waste such as lithium slag as the main raw material and forms a high-strength skeleton by composite specific fillers, realizing the high added value utilization of bulk solid waste, reducing material costs and reducing the consumption of natural aggregates; the activated solid waste core has good compatibility with cement matrix, which helps to improve the performance of concrete interface transition zone.

[0050] Enhancing the overall performance of concrete: The spherical particle shape is beneficial to improving the workability and pumpability of fresh concrete; the multi-stage release self-healing material is dispersed in the concrete as a "distributed repair micro-unit", and its multi-layer controlled release mechanism ensures the reliability and durability of the repair response, which can significantly improve the impermeability, durability and long-term service performance of concrete structures.

[0051] The process is feasible and easy to promote: the rolling granulation and layer-by-layer coating process adopted is mature and stable, the parameters are easy to control, and it is suitable for large-scale production, providing a solid foundation for industrial application.

[0052] Compared with the prior art, the advantages of the present invention are:

[0053] (1) This invention provides a multi-level release self-healing material with a unique five-layer core-shell structure that enables the time-controlled release of repair components, providing multiple and intelligent repair capabilities for concrete cracks and significantly extending the self-repair life of the structure.

[0054] (2) This invention realizes the large-scale resource utilization of industrial solid waste such as lithium slag in functional building materials, which has both environmental and economic benefits.

[0055] (3) The multi-stage release self-healing material provided by the present invention can be added to concrete as spherical aggregate to improve the construction performance of concrete and has good compatibility with cement matrix. While providing long-term self-healing function, it does not damage the basic mechanical properties of concrete.

[0056] (4) The preparation method of the multi-stage release self-healing material of the present invention is simple and controllable, easy to realize industrial production, and easy to apply, making it convenient to promote and use in various engineering projects. Attached Figure Description

[0057] Figure 1 This is a schematic diagram of the structure of the multi-stage release self-healing material of the present invention;

[0058] Figure 2 This is a physical image of the multi-stage release self-healing material of the present invention. Detailed Implementation

[0059] To enable those skilled in the art to clearly and completely understand the technical solution of the present invention, the present invention will be further described in detail below with reference to embodiments. Obviously, the embodiments described herein are only for explaining the present invention and are not intended to limit the scope of the present invention. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0060] Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art. Unless otherwise specified, the raw materials, methods and equipment used in this invention are conventional raw materials, methods and equipment in the art.

[0061] This invention provides a multi-stage release self-healing material, such as... Figure 1 As shown, the multi-stage release self-healing material has a multi-layer spherical core-shell structure, which includes, from the inside out: a solid waste core layer, an inner self-healing layer, an intermediate barrier protective layer, an outer self-healing layer, and an excitable functional protective layer.

[0062] The raw materials for the solid waste core layer include: 90-80 parts of lithium slag-based solid waste material and 10-20 parts of filler.

[0063] The raw materials of the inner self-healing layer include: 20-25 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 15-20 parts of ethylenediaminetetraacetic acid, 10-15 parts of metakaolin, 8-12 parts of polybasic organic acids, and 3-5 parts of sodium fluorosilicate.

[0064] The raw materials for the intermediate barrier protective layer include: 50-80 parts of lithium slag ultrafine powder, 15-20 parts of anhydrous gypsum, and 10-15 parts of sodium-based bentonite.

[0065] The raw materials of the external self-healing layer include: 20-25 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 15-25 parts of nano calcium carbonate, 12-16 parts of sodium aluminate, 10-15 parts of nano silica, and 3-5 parts of sodium tripolyphosphate.

[0066] The raw materials for the activating functional protective layer include: 35-45 parts calcium hydroxide, 25-35 parts sodium fluorosilicate, 15-25 parts stone powder, 1-3 parts redispersible polymer powder, and 1-3 parts stearate.

[0067] In some examples, the mass ratio of the solid waste core layer, the inner self-healing layer, the intermediate barrier protective layer, the outer self-healing layer, and the stimulating functional protective layer is (4~6):(23~27):(13~17):(33~37):(18~22).

[0068] In some examples, the diameter of the multi-stage release self-healing material is 20-30 mm.

[0069] In some examples, the diameter of the solid waste core layer is 2-5 mm, the thickness of the inner self-healing layer is 3-10 mm, the thickness of the intermediate barrier protective layer is 1-10 mm, the thickness of the outer self-healing layer is 2-14 mm, and the thickness of the stimulating functional protective layer is 1-4 mm.

[0070] In some examples, the lithium slag-based solid waste material includes, but is not limited to, at least one of spodumene slag and lepidolite slag. The lepidolite slag needs to undergo defluorination treatment (thermal activation at 500~600 °C to achieve defluorination) before being used to prepare the solid waste core layer, in order to eliminate the adverse effects of fluorides on cement hydration. The filler includes, but is not limited to, at least one of fly ash, silica fume, and stone powder.

[0071] In some examples, the ethylenediaminetetraacetic acid salt includes, but is not limited to, at least one of disodium ethylenediaminetetraacetate and tetrasodium ethylenediaminetetraacetate; the polybasic organic acid includes, but is not limited to, at least one of fumaric acid, citric acid, and succinic acid.

[0072] In some examples, the stearate includes, but is not limited to, at least one of calcium stearate, zinc stearate, and magnesium stearate.

[0073] The present invention uses a "rotary disk granulation-sequential encapsulation" preparation process to prepare the multi-level release self-healing material. The key is to achieve a multi-layered structure with distinct layers and strong bonding by precisely controlling the feeding sequence, atomized water volume and granulation time. Specifically, this invention first thoroughly mixes the raw materials for each layer; then, the solid waste core layer material is placed into a rotating granulation disc, and under the rotation of the disc, a first spray of atomized water is applied, causing the solid waste core layer material to agglomerate and spherical through capillary force, forming dense and uniform spherical core particles; then, based on the spherical core particles, an inner self-healing layer, an intermediate barrier protective layer, an outer self-healing layer, and an activating functional protective layer are constructed layer by layer: the inner self-healing layer material is continuously and uniformly added to the spherical core particles, and a second spray of atomized water is applied simultaneously, causing the material to adhere evenly to the surface of the core particles, forming a preliminary double-layer spherical structure; the intermediate barrier protective layer material is added to the double-layer spheres, and a third spray of atomized water is applied simultaneously, forming a three-layer spherical structure; the outer self-healing layer material is added to the three-layer spheres, and a fourth spray of atomized water is applied simultaneously, forming a four-layer spherical structure; the activating functional protective layer material is added to the four-layer spheres, and a fifth spray of atomized water is applied simultaneously, completing the construction of the final five-layer spherical particle structure. Each step requires precise control of process parameters to ensure clear interlayer interfaces, uniform thickness, and strong bonding. Finally, the five-layer spherical particles are placed under conditions of 20 ± 2 ℃ and relative humidity > 95% for more than 7 days of covering and moisturizing maintenance to give them the necessary initial strength and stability for easy storage, transportation, and use.

[0074] The multi-stage release self-healing material provided by this invention can be directly used as a functional aggregate during the concrete mixing stage. The recommended dosage is 1%-2% of the total mass of cementitious materials (cement and mineral admixtures) in the concrete. At this dosage, the multi-stage release self-healing material can be uniformly dispersed in the concrete, achieving optimal self-healing effects without negatively impacting the workability and basic mechanical properties of the concrete. Specifically, the effects of the multi-stage release self-healing material include:

[0075] Innovative multi-level release repair mechanism: The unique five-layer core-shell structure enables "on-demand release" and "multiple responses" of the repair behavior; the outermost excitable functional protective layer deals with early micro-damage, while the inner repair agent reserve is used to deal with more severe subsequent cracking, which greatly extends the effective repair cycle and repair depth of the material;

[0076] Excellent repair performance: The nanomaterials in the self-healing layer can quickly generate dense healing products such as calcium carbonate and CSH gel at the crack, effectively restoring the structure's impermeability and mechanical properties. The crack repair rate (width direction) can reach more than 90%.

[0077] Significant environmental and economic benefits: The solid waste core layer enables large-scale, high-value utilization of industrial solid wastes such as lithium slag (utilization rate > 80%), reducing material costs and meeting the requirements of circular economy and sustainable development;

[0078] Excellent construction and long-term performance: Spherical particles improve the rheological properties of fresh concrete and reduce pumping resistance; the main components of the material are inorganic substances, which have good chemical compatibility with cement matrix, match the coefficient of thermal expansion, have high long-term stability, and will not introduce harmful side effects.

[0079] The technology is mature and easy to industrialize: the rolling granulation process equipment is universal and the parameters are easy to control, making it suitable for continuous and large-scale production, and the product quality is stable and reliable.

[0080] As can be seen, this invention, through its ingenious structural design, combines solid waste resource utilization, material multifunctionality, and intelligent concrete maintenance, providing an innovative, efficient, and green solution for improving the durability and safety of major infrastructure projects.

[0081] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments.

[0082] Example 1

[0083] In this embodiment, a multi-stage release self-healing material with a total mass of 1000 g was prepared according to a five-layer mass ratio of solid waste core layer: inner self-healing layer: intermediate barrier layer: outer self-healing layer: outer excitation protection layer = 5:25:15:35:20, with a target particle size of 20~30mm.

[0084] The raw materials for each layer of the multi-stage release self-healing material are as follows:

[0085] Solid waste core layer (5%, i.e., 50 g): 85 parts spodumene slag, 15 parts fly ash;

[0086] Inner self-healing layer (25%, i.e., 250 g): 22 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 18 parts of disodium ethylenediaminetetraacetate, 12 parts of metakaolin, 10 parts of fumaric acid, and 4 parts of sodium fluorosilicate.

[0087] Intermediate barrier protective layer (15%, i.e., 150 g): Lithium slag ultrafine powder (specific surface area ≥ 650 m²) 2 65 parts ( / kg), 18 parts anhydrous gypsum, and 12 parts sodium bentonite;

[0088] External self-healing layer (35%, i.e., 350 g): 22 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 20 parts of nano calcium carbonate, 14 parts of sodium aluminate, 12 parts of nano silica, and 4 parts of sodium tripolyphosphate;

[0089] Externally activated functional protective layer (20%, i.e., 200 g): 40 parts calcium hydroxide, 30 parts sodium fluorosilicate, 20 parts stone powder (100~200 mesh), 2 parts redispersible polymer powder (VAE type), and 2 parts calcium stearate.

[0090] The preparation steps for each layer of the multi-stage release self-healing material are as follows:

[0091] S1. Mixing of raw materials:

[0092] Lithium spodumene slag and fly ash are mixed evenly to obtain the solid waste core layer material;

[0093] Medium-dissolving sodium silicate, disodium ethylenediaminetetraacetate, metakaolin, fumaric acid, and sodium fluorosilicate are mixed evenly to obtain an inner self-healing layer material.

[0094] Lithium slag ultrafine powder, anhydrous gypsum, and sodium-based bentonite are mixed evenly to obtain an intermediate barrier protective layer material.

[0095] The fast-dissolving sodium silicate, nano-calcium carbonate, sodium aluminate, nano-silica, and sodium tripolyphosphate are mixed evenly to obtain an external self-healing layer material.

[0096] Calcium hydroxide, sodium fluorosilicate, stone powder, redispersible polymer powder, and calcium stearate are mixed evenly to obtain an activating functional protective layer material.

[0097] S2, Granulation:

[0098] The solid waste core layer material is fed into a rotating granulation disc for spherical granulation, while a first atomized water is sprayed in. The granulation time is controlled at 9 minutes to form core skeleton material balls. The amount of the first atomized water sprayed in is 15% of the mass of the solid waste core layer material.

[0099] S3. Preparation of the inner self-healing layer:

[0100] Add an inner self-healing layer material to the core skeleton sphere, and simultaneously spray a second atomized water, controlling the granulation time to 7 minutes to form a double-layer structure sphere; the amount of the second atomized water sprayed is 15% of the mass of the inner self-healing layer material.

[0101] S4. Preparation of the intermediate barrier protective layer:

[0102] A middle barrier protective layer material is added to the double-layer structured granules, and a third atomized water is sprayed in at the same time. The granulation time is controlled to be 6 minutes to form a three-layer structured granules. The amount of the third atomized water sprayed in is 10% of the mass of the middle barrier protective layer material.

[0103] S5. Preparation of the external self-healing layer:

[0104] Add an outer self-healing layer material to the three-layer structured spheres, and simultaneously spray a fourth atomized water, controlling the granulation time to 7 minutes to form a four-layer structured sphere; the amount of the fourth atomized water sprayed is 15% of the mass of the outer self-healing layer material.

[0105] S6. Preparation of the protective layer for stimulating functional activity:

[0106] An activating functional protective layer material is added to a four-layer structured granule, and a fifth atomized water is sprayed in simultaneously. The granulation time is controlled at 8 minutes to obtain a five-layer structured granule. The amount of the fifth atomized water sprayed in is 12% of the mass of the activating functional protective layer material.

[0107] Five-layer structured material balls were covered with a damp cloth and cured for 7 days at 20 ± 2 ℃ and humidity ≥ 95% to obtain a multi-stage release self-healing material (such as...). Figure 2 (As shown).

[0108] Example 2

[0109] The preparation method of the multi-stage release self-healing material in this embodiment is basically the same as that in Example 1. The difference from Example 1 is that the raw materials of each layer of the multi-stage release self-healing material in this embodiment are as follows:

[0110] Solid waste core layer: 80 parts of defluorinated lithium mica residue and 20 parts of silica fume;

[0111] Internal self-healing layer: 20 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 15 parts of disodium ethylenediaminetetraacetate, 10 parts of metakaolin, 8 parts of fumaric acid, and 3 parts of sodium fluorosilicate;

[0112] Intermediate barrier protective layer: 50 parts lithium slag ultrafine powder, 15 parts anhydrous gypsum, and 10 parts sodium-based bentonite.

[0113] External self-healing layer: 20 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 15 parts of nano calcium carbonate, 12 parts of sodium aluminate, 10 parts of nano silica, and 3 parts of sodium tripolyphosphate;

[0114] Externally activated protective layer: 35 parts calcium hydroxide, 25 parts sodium fluorosilicate, 15 parts stone powder, 1 part redispersible polymer powder, and 1 part calcium stearate.

[0115] Example 3

[0116] The preparation method of the multi-stage release self-healing material in this embodiment is basically the same as that in Example 1. The difference from Example 1 is that the raw materials of each layer of the multi-stage release self-healing material in this embodiment are as follows:

[0117] Solid waste core layer: 90 parts spodumene slag, 10 parts stone powder;

[0118] Internal self-healing layer: 25 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 20 parts of disodium ethylenediaminetetraacetate, 15 parts of metakaolin, 12 parts of fumaric acid, and 5 parts of sodium fluorosilicate;

[0119] Intermediate barrier protective layer: 80 parts lithium slag ultrafine powder, 20 parts anhydrous gypsum, and 15 parts sodium-based bentonite;

[0120] External self-healing layer: 25 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 25 parts of nano calcium carbonate, 16 parts of sodium aluminate, 15 parts of nano silica, and 5 parts of sodium tripolyphosphate;

[0121] Externally activated protective layer: 45 parts calcium hydroxide, 35 parts sodium fluorosilicate, 25 parts stone powder, 3 parts redispersible polymer powder, and 3 parts calcium stearate.

[0122] Comparative Example 1

[0123] The difference between this comparative example and Example 1 is that the intermediate barrier protective layer is omitted, the five-layer structure is changed to a four-layer structure, and the mass ratio of each layer is adjusted to: solid waste core layer: inner self-healing layer: outer self-healing layer: outer activation protective layer = 5:35:40:20. The raw material ratio (parts) of each layer is the same as in Example 1, only the actual mass of each layer is adjusted, and the particle size of the final self-healing material is basically the same as that in Example 1.

[0124] The raw material ratios (total mass 1000 g) for each layer of the self-healing material in this comparative example are as follows:

[0125] Solid waste core layer (5%, 50 g): 42.5 g (85 parts) of spodumene slag, 7.5 g (15 parts) of fly ash;

[0126] Internal self-healing layer (35%, 350 g): 77 g (22 parts) of medium-dissolving sodium silicate (modulus 3.0-3.2), 63 g (18 parts) of disodium ethylenediaminetetraacetate, 42 g (12 parts) of metakaolin, 35 g (10 parts) of fumaric acid, and 14 g (4 parts) of sodium fluorosilicate.

[0127] External self-healing layer (40%, 400 g): 88 g (22 parts) of fast-dissolving sodium silicate (modulus 2.0-2.2), 80 g (20 parts) of nano calcium carbonate, 56 g (14 parts) of sodium aluminate, 48 g (12 parts) of nano silica, and 16 g (4 parts) of sodium tripolyphosphate.

[0128] External excitation protective layer (20%, 200 g): 80 g calcium hydroxide (40 parts), 60 g sodium fluorosilicate (30 parts), 40 g stone powder (20 parts), 4 g redispersible polymer powder (2 parts), 4 g calcium stearate (2 parts).

[0129] The other preparation process is the same as in Example 1 (without the intermediate barrier protective layer).

[0130] Comparative Example 2

[0131] The difference between this comparative example and Example 1 is that the external excitation functional protective layer is omitted, and the five-layer structure is changed to a four-layer structure. The mass ratio of each layer is adjusted to: solid waste core layer: inner self-healing layer: intermediate barrier layer: outer self-healing layer = 5:30:18:47. The raw material ratio (parts) of each layer is the same as in Example 1, only the actual mass of each layer is adjusted, and the particle size of the final self-healing material is basically the same as that in Example 1.

[0132] The raw material ratios (total mass 1000 g) for each layer of the self-healing material in this comparative example are as follows:

[0133] Solid waste core layer (5%, 50 g): 42.5 g (85 parts) of spodumene slag, 7.5 g (15 parts) of fly ash;

[0134] Inner self-healing layer (30%, 300 g): 66 g (22 parts) of medium-dissolving sodium silicate, 54 g (18 parts) of disodium ethylenediaminetetraacetate, 36 g (12 parts) of metakaolin, 30 g (10 parts) of fumaric acid, and 12 g (4 parts) of sodium fluorosilicate.

[0135] Intermediate barrier protective layer (18%, 180 g): 117 g (65 parts) of lithium slag ultrafine powder, 32.4 g (18 parts) of anhydrous gypsum, and 21.6 g (12 parts) of sodium-based bentonite.

[0136] External self-healing layer (47%, 470 g): 103.4 g (22 parts) of fast-dissolving sodium silicate, 94 g (20 parts) of nano calcium carbonate, 65.8 g (14 parts) of sodium aluminate, 56.4 g (12 parts) of nano silica, and 18.8 g (4 parts) of sodium tripolyphosphate.

[0137] The other preparation process is the same as in Example 1 (without the outer protective layer coating step).

[0138] Comparative Example 3

[0139] The difference between this comparative example and Example 1 is that sodium fluorosilicate is not added to the externally excited functional protective layer; its proportion is made up by inert stone powder. The mass ratio of the five layers and the inner layer ratio are exactly the same as in Example 1 (5:25:15:35:20, total mass 1000g), only the composition of the externally excited functional protective layer is changed.

[0140] The raw materials for the externally activated functional protective layer (200 g) are as follows: 80 g calcium hydroxide, 112 g stone powder, 4 g adhesive powder, and 4 g calcium stearate.

[0141] The other layers are exactly the same as in Example 1, and the preparation process is the same.

[0142] Comparative Example 4

[0143] The difference between this comparative example and Example 1 is that calcium hydroxide is not added to the external excitation protective layer; its proportion is made up by inert stone powder. The mass ratio of the five layers and the inner layer ratio are exactly the same as in Example 1 (5:25:15:35:20, total mass 1000 g), only the composition of the external excitation functional protective layer is changed.

[0144] The composition of the externally excited functional protective layer (200 g) is as follows: sodium fluorosilicate 60 g, stone powder 132 g, adhesive powder 4 g, calcium stearate 4 g.

[0145] The other layers are exactly the same as in Example 1, and the preparation process is the same.

[0146] Comparative Example 5

[0147] The difference between this comparative example and Example 1 is that disodium ethylenediaminetetraacetate is not added to the inner self-healing layer; its proportion is made up by sodium silicate. The mass ratio of the five layers and the inner layer ratio are exactly the same as in Example 1 (5:25:15:35:20, total mass 1000g), only the composition of the inner self-healing layer is changed.

[0148] The internal self-healing layer (250 g) consists of the following components: 152 g of medium-dissolving sodium silicate, 45 g of metakaolin, 38 g of fumaric acid, and 15 g of sodium fluorosilicate.

[0149] The other layers are exactly the same as in Example 1, and the preparation process is the same.

[0150] Comparative Example 6

[0151] This comparative example does not employ the five-layer core-shell structure of this invention, but instead uses a single-layer self-healing layer directly formed into particles using existing technology. The specific formulation is as follows: 208 g sodium silicate, 208 g nano-calcium carbonate, 125 g nano-silica, 125 g sodium aluminate, 125 g disodium EDTA, 84 g fumaric acid, 83 g sodium tripolyphosphate, and 42 g sodium fluorosilicate.

[0152] Preparation process: Sodium silicate, nano calcium carbonate, nano silica, sodium aluminate, disodium ethylenediaminetetraacetate, fumaric acid, sodium tripolyphosphate, and sodium fluorosilicate are uniformly mixed to obtain a single-layer self-healing material. Atomized water is sprayed into the mixture to form spherical granules. The amount of atomized water is 15% of the powder mass.

[0153] Comparative Example 7

[0154] The difference between this comparative example and Example 1 is that, while keeping everything else unchanged, the raw materials of the inner and outer self-healing layers are replaced, and the preparation method is the same as in Example 1. That is, in this comparative example, the mass ratio of solid waste core layer: inner self-healing layer: intermediate barrier layer: outer self-healing layer: outer excitation protective layer is 5:25:15:35:20, and the target particle size is 20~30 mm;

[0155] The raw materials for the inner self-healing layer are as follows: 22 parts of fast-dissolving sodium silicate (modulus 2.0-2.2), 20 parts of nano calcium carbonate, 14 parts of sodium aluminate, 12 parts of nano silica, and 4 parts of sodium tripolyphosphate;

[0156] The raw materials for the external self-healing layer are as follows: 22 parts of medium-dissolving sodium silicate (modulus 3.0-3.2), 18 parts of disodium ethylenediaminetetraacetate, 12 parts of metakaolin, 10 parts of fumaric acid, and 4 parts of sodium fluorosilicate.

[0157] Concrete specimens were prepared using C30 grade concrete for testing. The batching mass of the concrete compressive strength and self-healing ability tests for the benchmark group, examples, and comparative examples is shown in Table 1. The batching mass of the concrete impermeability test is shown in Table 2. In the examples and comparative examples of this invention, the self-healing material replaced a portion of the cement at a dosage of 2% of the cement mass.

[0158] Table 1: Concrete compressive strength and self-healing test mix proportions

[0159]

[0160] Table 2: Concrete permeability test mix proportions

[0161]

[0162] Concrete performance testing:

[0163] The slump of concrete was tested according to GB / T50080-2002 "Test Methods for Performance of Ordinary Concrete Mixtures"; the compressive strength ratio, impermeability, and self-healing ability of concrete test blocks were tested according to standard GB / T18445-2025 "Cement-based Penetrating Crystalline Waterproofing Materials".

[0164] The performance of various properties of the concrete specimens formed by the test benchmark group, Examples 1-5 of the present invention and Comparative Examples 1-7 are shown in Tables 3-5.

[0165] Table 3: Compressive strength test results of the benchmark group, the embodiments of the present invention, and the comparative examples.

[0166]

[0167] Table 4: Impermeability test results of the benchmark group, embodiments of the present invention, and comparative examples

[0168]

[0169] Table 5: Self-healing capability test results of the benchmark group, embodiments of the present invention, and comparative examples.

[0170]

[0171] In summary, this invention, through ingenious structural design, combines solid waste resource utilization, material multifunctionality, and intelligent concrete maintenance. It provides a multi-stage release self-healing material with good compatibility with concrete, capable of responding on demand and releasing repair agents in stages. This achieves more intelligent, efficient, and durable self-repair of concrete cracks, offering an innovative, efficient, and green solution for improving the durability and safety of major infrastructure projects. The multi-stage release self-healing material is directly used as a functional aggregate during the concrete mixing stage, with a recommended dosage of 1%-2% of the total mass of cementitious materials (cement and mineral admixtures) in the concrete. At this dosage, the multi-stage release self-healing material can be uniformly dispersed in the concrete, achieving optimal self-healing effects without negatively impacting the workability and basic mechanical properties of the concrete.

[0172] The above detailed embodiments describe the implementation of the present invention; however, the present invention is not limited to the specific details described in the above embodiments. Within the scope of the claims and technical concept of the present invention, various simple modifications and changes can be made to the technical solution of the present invention, and these simple modifications all fall within the protection scope of the present invention.

Claims

1. A multi-stage release self-healing material, characterized in that, The multi-stage release self-healing material has a multi-layer spherical core-shell structure, which includes, from the inside out: a solid waste core layer, an inner self-healing layer, an intermediate barrier protective layer, an outer self-healing layer, and an excitable functional protective layer. The raw materials for the solid waste core layer include: 90-80 parts of lithium slag-based solid waste material and 10-20 parts of filler. The raw materials of the inner self-healing layer include: 20-25 parts of medium-dissolving sodium silicate, 15-20 parts of ethylenediaminetetraacetic acid, 10-15 parts of metakaolin, 8-12 parts of polybasic organic acid, and 3-5 parts of sodium fluorosilicate. The raw materials for the intermediate barrier protective layer include: 50-80 parts of lithium slag ultrafine powder, 15-20 parts of anhydrous gypsum, and 10-15 parts of sodium-based bentonite. The raw materials of the external self-healing layer include: 20-25 parts of fast-dissolving sodium silicate, 15-25 parts of nano calcium carbonate, 12-16 parts of sodium aluminate, 10-15 parts of nano silica, and 3-5 parts of sodium tripolyphosphate. The raw materials for the activating functional protective layer include: 35-45 parts calcium hydroxide, 25-35 parts sodium fluorosilicate, 15-25 parts stone powder, 1-3 parts redispersible polymer powder, and 1-3 parts stearate.

2. The multi-stage release self-healing material according to claim 1, characterized in that, The mass ratio of the solid waste core layer, inner self-healing layer, intermediate barrier protection layer, outer self-healing layer and stimulating functional protection layer is (4~6):(23~27):(13~17):(33~37):(18~22).

3. The multi-stage release self-healing material according to claim 2, characterized in that, The diameter of the multi-stage release self-healing material is 20~30 mm.

4. The multi-stage release self-healing material according to claim 2, characterized in that, The diameter of the solid waste core layer is 3-4 mm; and / or, The thickness of the inner self-healing layer is 5-8 mm; and / or, The thickness of the intermediate barrier protective layer is 3-5 mm; and / or, The thickness of the external self-healing layer is 6-10 mm; and / or, The thickness of the excitatory functional protective layer is 2~3 mm.

5. The multi-stage release self-healing material according to claim 1, characterized in that, The lithium slag-based solid waste material includes, but is not limited to, at least one of spodumene slag and lepidolite slag; and / or, the filler includes, but is not limited to, at least one of fly ash, silica fume, and stone powder.

6. The multi-stage release self-healing material according to claim 1, characterized in that, The polybasic organic acids include, but are not limited to, at least one of fumaric acid, citric acid, and succinic acid.

7. The multi-stage release self-healing material according to claim 1, characterized in that, The stearates include, but are not limited to, at least one of calcium stearate, zinc stearate, and magnesium stearate.

8. A method for preparing the multi-stage release self-healing material according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Mix lithium slag-based solid waste materials and fillers evenly according to the specified proportions to obtain the solid waste core layer material; mix medium-dissolving sodium silicate, ethylenediaminetetraacetate, metakaolin, multi-element organic acids, and sodium fluorosilicate evenly according to the specified proportions to obtain the inner self-healing layer material; mix lithium slag ultrafine powder, anhydrous gypsum, and sodium-based bentonite evenly according to the specified proportions to obtain the intermediate barrier protective layer material; mix fast-dissolving sodium silicate, nano-calcium carbonate, sodium aluminate, nano-silica, and sodium tripolyphosphate evenly according to the specified proportions to obtain the outer self-healing layer material; mix calcium hydroxide, sodium fluorosilicate, stone powder, redispersible polymer powder, and stearate evenly according to the specified proportions to obtain the activating functional protective layer material. S2. The solid waste core layer material is spherically granulated, and a first atomized water is sprayed in to form core skeleton material balls. S3. Add an inner self-healing layer material to the core skeleton sphere and spray a second atomized water to form a double-layer structure sphere. S4. Add intermediate barrier protective layer material to the double-layer structured sphere, and spray a third atomized water to form a three-layer structured sphere. S5. Add an outer self-healing layer material to the three-layer structured sphere, and simultaneously spray a fourth layer of atomized water to form a four-layer structured sphere. S6. Add an activating functional protective layer material to the four-layer structured material ball, and simultaneously spray a fifth atomized water to obtain a five-layer structured material ball; cover and moisturize the five-layer structured material ball to obtain a multi-stage release self-healing material.

9. The method for preparing the multi-stage release self-healing material according to claim 8, characterized in that, The initial injection volume of atomized water is 10% to 15% of the mass of the solid waste core layer material; and / or, The amount of the second atomized water sprayed is 14% to 19% of the mass of the inner self-healing layer material; and / or, The amount of atomized water injected in the third stage is 7% to 11% of the mass of the intermediate barrier protective layer material; and / or, The amount of atomized water injected in the fourth stage is 15% to 20% of the mass of the external self-healing layer material; and / or, The amount of atomized water injected in the fifth stage is 10% to 14% of the mass of the activating functional protective layer material.

10. The application of the multi-stage release self-healing material according to any one of claims 1-7 or the multi-stage release self-healing material prepared by the preparation method according to claim 9 in the preparation of building materials, characterized in that, The multi-stage release self-healing material is incorporated into the building material at a rate of 1% to 2% of the total mass of the gel material.

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