High durability lightweight ceramsite concrete with quick demoulding and its preparation method

Abstract

The application discloses a kind of high durability lightweight ceramsite concrete of quick demoulding and preparation method thereof, and the concrete includes the components with mass fraction as follows: fly ash: 140~180 parts;Blast furnace slag: 90~120 parts;Silicate cement clinker micro powder: 40~70 parts;Alkaline activator: 80‑100 parts;Alkali-aggregate reaction inhibitor: 1.5~3.5 parts;Mixing water: 35~50 parts;Ceramsite aggregate: 900~950 parts;High efficiency water reducing agent: 1.0~1.5 parts;Internal curing material: 10~15 parts;Anti-cracking fiber: 0.5~2 parts;Compensation shrinkage material: 12~18 parts;By introducing cement clinker micro powder to form composite cementitious system to reduce pore solution effective alkalinity, while in the activator complex lithium salt inhibitor makes it preferentially react with active silicon dioxide to generate non-expansion product, and by adopting triple anti-cracking system composed of internal curing material, anti-cracking fiber and compensation shrinkage material, on the premise of not sacrificing rapid demoulding, the core production efficiency, fundamentally reduce the alkali content of system, improve its volume stability, the obtained concrete material has excellent early performance and reliable long-term durability.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a high-durability, quick-release lightweight expanded clay concrete and its preparation method. Background Technology

[0002] Lightweight expanded clay aggregate concrete, due to its low density and good thermal insulation properties, is widely used in precast components such as building wall panels. Geopolymers, as a new type of green cementitious material, have advantages such as high early strength, high temperature resistance, and corrosion resistance. Combining these two materials to develop precast components with rapid demolding can greatly improve production efficiency and meet the needs of industrialized construction. However, in pursuit of ultimate early strength to achieve rapid demolding, common technical approaches include using high-concentration, highly alkaline chemical activators and reducing the water-cement ratio to increase density and early strength. While these measures can effectively shorten demolding time, they have adverse effects on the long-term durability of the material, posing significant hidden dangers.

[0003] Alkali-aggregate reaction (ASR) risk: High-alkali activators used to achieve early strength result in extremely high concentrations of alkali metal ions (free alkali) in the pore fluid. The expanded clay aggregate itself may contain active silica components, or its raw materials may have potential reactivity. In humid environments, the alkali reacts with the active aggregate, forming a water-absorbing and expanding gel, causing expansion stress within the concrete, ultimately leading to cracking and failure. This is a delayed and irreversible form of damage, posing a long-term threat to structural safety.

[0004] High risk of shrinkage cracking: The shrinkage problem of geopolymer concrete is more serious in rapid demolding systems. This is the result of the superposition of two mechanisms: chemical shrinkage and drying shrinkage. On the one hand, the low water-cement ratio and high alkalinity formula adopted to achieve ultra-early strength exacerbates the chemical shrinkage in the early stage of reaction. This manifests as self-shrinkage internally, inducing tensile stress in the early stage of hardening and creating hidden dangers for microcracks. On the other hand, drying shrinkage has a greater impact. Rapid demolding exposes the component to the drying environment too early, and internal moisture migrates to the surface and evaporates. Especially when the setting rate is accelerated, the release of a large amount of heat of reaction will accelerate the loss of moisture, resulting in significant macroscopic volume shrinkage. At the same time, if the lightweight ceramsite is not pre-wetted enough, it will further deplete the moisture in the paste and exacerbate local drying. These factors make the magnitude and rate of drying shrinkage far exceed that of chemical shrinkage, further increasing the risk of shrinkage cracking.

[0005] In summary, the fundamental contradiction in existing rapid demolding geopolymer ceramsite concrete technologies lies in the conflict between the technical approach to achieving ultra-early strength (high alkali, low water-cement ratio, high temperature) and the inherent requirement to ensure long-term durability (low-alkali environment, volume stability). Therefore, the urgent technical challenge in this field is how to fundamentally reduce the alkali content and improve the volume stability of the system through material modification and process innovation, without significantly sacrificing the core production efficiency of rapid demolding, thereby developing lightweight geopolymer concrete materials that combine excellent early performance with reliable long-term durability. Summary of the Invention

[0006] In view of this, this application provides a high-durability, rapidly demoldable lightweight ceramsite concrete and its preparation method, to solve the problem of how to make lightweight geopolymer concrete materials have both excellent early performance and reliable long-term durability.

[0007] To achieve the above technical objectives, this application adopts the following technical solution: This application provides a high-durability, quick-release lightweight ceramsite concrete, comprising the following components by mass fraction: fly ash: 140-180 parts; blast furnace slag: 90-120 parts; silicate cement clinker powder: 40-70 parts; alkaline activator: 80-100 parts; alkali-aggregate reaction inhibitor: 1.5-3.5 parts; mixing water: 35-50 parts; ceramsite aggregate: 900-950 parts; high-efficiency water-reducing agent: 1.0-1.5 parts; internal curing material: 10-15 parts; crack-resistant fiber: 0.5-2 parts; shrinkage compensation material: 12-18 parts.

[0008] Preferably, the fly ash residue on a 45μm sieve is ≤12%; the blast furnace slag is S95 grade or higher slag powder with a specific surface area ≥400 m². 2 / kg; Specific surface area of ​​silicate cement clinker powder ≥350 m² 2 / kg.

[0009] Preferably, the alkaline activator is a mixed solution of water glass and sodium hydroxide, and the modulus of the alkaline activator is 1.4-1.6.

[0010] Preferably, the water glass is an industrial sodium silicate aqueous solution with a modulus of 2.8-3.3; and the sodium hydroxide is industrial grade sodium hydroxide with a purity of ≥98%.

[0011] Preferably, the alkali-aggregate reaction inhibitor is lithium carbonate and / or lithium hydroxide.

[0012] Preferably, the ceramsite aggregate has a bulk density of 700~800 kg / m³. 3 It is composed of 5-10mm ceramsite and 0-5mm ceramsite sand in a mass ratio of 1:(1.2-1.4).

[0013] Preferably, the high-efficiency water-reducing agent is a naphthalene-based water-reducing agent.

[0014] Preferably, the internal curing material is pre-water-saturated lightweight porous ceramic sand or zeolite powder.

[0015] Preferably, the crack-resistant fiber is a coarse polypropylene fiber with a length of 12~19mm.

[0016] Preferably, the shrinkage-compensating material is a calcium sulfoaluminate or calcium oxide-based expansion agent.

[0017] Secondly, this application provides a method for preparing lightweight ceramsite concrete with high durability and rapid demolding capability, comprising the following steps: An activator solution is obtained by mixing an alkaline activator with an alkali-aggregate reaction inhibitor and then aging the mixture. Fly ash, blast furnace slag, silicate cement clinker powder, and ceramsite aggregate are mixed and then dry-mixed to obtain a mixture. The high-efficiency water-reducing agent and shrinkage-compensating material are dissolved, then mixed with the activator solution, and finally the internal curing material is added to obtain the mixture. Add the liquid to the mixture and perform wet mixing. Then add the crack-resistant fiber to obtain the dry-hard concrete mixture. Lightweight expanded clay concrete is obtained by molding, demolding, and curing the dry-hard concrete mixture.

[0018] The beneficial effects of this application are as follows: This application introduces cement clinker micro powder to form a composite cementitious system to reduce the effective alkalinity of the pore solution. At the same time, lithium salt inhibitors are compounded in the activator to preferentially react with active silica to generate non-expansion products. This works by reducing the driving potential and blocking the reaction path, thus completely eliminating the risk of alkali-aggregate reaction. Furthermore, by using a triple crack-resistant system composed of internal curing materials, crack-resistant fibers, and shrinkage compensation materials, it plays a role in three dimensions: moisture migration inhibition, tensile stress transfer, and volume compensation. This system controls plastic shrinkage, autogenous shrinkage, and drying shrinkage throughout the entire process at multiple scales, resulting in a significant improvement in crack resistance. This application uses fly ash, slag, ordinary ceramic sand and other bulk industrial solid waste or common building materials as the main raw materials, and adopts 6 to 8 hours of short-term steam curing to replace traditional long-term curing, which reduces material costs and energy consumption by more than 60%. This application utilizes an optimized ternary composite system to ensure stable and reliable early strength development, allowing for safe demolding within 2 to 4 hours. Simultaneously, pre-aging treatment with an activator and step-by-step feeding and stirring ensure product quality stability and repeatability. Detailed Implementation

[0019] The embodiments of the technical solution of this application will be described in detail below. The following embodiments are only used to illustrate the technical solution of this application more clearly, and are therefore only examples, and should not be used to limit the scope of protection of this application.

[0020] In the description of the embodiments of this application, technical terms such as "first" and "second" are used only to distinguish different objects and should not be construed as indicating or implying relative importance or implicitly specifying the number, specific order, or primary and secondary relationship of the indicated technical features. In the description of the embodiments of this application, "multiple" means two or more, unless otherwise explicitly defined.

[0021] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0022] In the description of the embodiments in this application, the term "and / or" is merely a description of the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, and B existing alone. Additionally, the character " / " in this document generally indicates that the preceding and following related objects have an "or" relationship.

[0023] Unless otherwise explicitly defined and specified herein, all technical and scientific terms used in this application shall have the generally accepted meanings understood by one of ordinary skill in the field of chemical and chemical materials technology (including but not limited to polymer chemistry, inorganic chemistry, organic synthesis, catalysis chemistry, materials processing, and chemical unit operations) based on their professional knowledge and conventional practice. The use of any terminology herein is intended to describe the specific embodiments of this application in the clearest and most accurate manner, so as to fully disclose the technical solution. Such use shall not in any way be construed as a limitation on the scope of the claims, nor does it imply the exclusion of equivalent technical solutions that could be reasonably known by one of skill in the art based on the concept of this application.

[0024] The terms "comprising," "including," "having," "containing," and any grammatical variations or similar expressions used in the specification and claims of this application are all open-ended and non-exhaustive descriptive terms. Their purpose is to explicitly describe the existence of technical features, components, steps, or parts, while explicitly allowing and covering the possibility that other features, components, steps, parts, or any combinations thereof not explicitly listed may exist or be added to the technical solution, as long as such additions do not destroy the integrity and inventiveness of the original technical solution.

[0025] When the terms "embodiments," "some embodiments," or "specific embodiments" are mentioned in the specification, they refer to examples that, in conjunction with the specific parameters, materials, steps, and results described in that section, constitute one or a group of examples for implementing the technical solutions of this application. These embodiments are used for full disclosure and illustrative purposes, not for exhaustive enumeration. Those skilled in the art should understand that, without departing from the overall inventive concept of this application, the various technical features disclosed in different embodiments can be combined, substituted, modified, or deleted to form other implementation methods that are not listed one by one in the specification but also fall within the protection scope of this application.

[0026] Unless otherwise expressly specified and limited, all terms related to chemical process operations, material preparation, processing and analytical testing involved in this application shall be interpreted in the broadest sense based on the conventional understanding of those skilled in the art.

[0027] Regarding performance testing and structural characterization, all testing and characterization methods involved in this application, unless otherwise specified, refer to conventional methods known in the art. Specific testing conditions may be selected and adjusted according to the sample properties and relevant national standards, international standards, or industry-standard methods. Test items may include mechanical properties (such as tensile, bending, and impact strength), thermal properties (such as DSC and TGA analysis), and chemical stability (such as solvent resistance and acid / alkali corrosion resistance). Structural characterization methods may include FT-IR, NMR, XRD, SEM, TEM, and BET. All test results should be understood to be within the allowable range of conventional experimental errors.

[0028] Regarding numerical values ​​and ranges, all parameter ranges expressed in this application in the form of "from a certain value to a certain value" should be understood as explicitly disclosing the endpoints of the range, each specific numerical point between the endpoints, and all sub-ranges formed by any two numerical points within the range. For example, "30℃ to 80℃" discloses 30, 31, ..., 80℃, as well as sub-ranges such as 30-50℃, 45-70℃, etc. When a numerical value is preceded by "about," "approximately," or similar words, it indicates that the numerical value is allowed to have reasonable errors recognized in the art under the measurement or control conditions, which can generally be understood as the deviation allowed by relevant standards or a normal fluctuation range of ±5% or ±10%.

[0029] This application provides a high-durability, quick-release lightweight ceramsite concrete, comprising the following components by mass fraction: fly ash: 140-180 parts; blast furnace slag: 90-120 parts; silicate cement clinker powder: 40-70 parts; alkaline activator: 80-100 parts; alkali-aggregate reaction inhibitor: 1.5-3.5 parts; mixing water: 35-50 parts; ceramsite aggregate: 900-950 parts; high-efficiency water-reducing agent: 1.0-1.5 parts; internal curing material: 10-15 parts; crack-resistant fiber: 0.5-2 parts; shrinkage compensation material: 12-18 parts.

[0030] This application introduces cement clinker micropowder to form a composite cementitious system to reduce the effective alkalinity of the pore solution. At the same time, lithium salt inhibitors are compounded in the activator to preferentially react with active silica to generate non-expansion products. This works by reducing the driving potential and blocking the reaction path, thus completely eliminating the risk of alkali-aggregate reaction. Furthermore, by adopting a triple crack-resistant system composed of internal curing materials, crack-resistant fibers, and shrinkage-compensating materials, it plays a role in three dimensions: moisture migration inhibition, tensile stress transfer, and volume compensation. This system controls plastic shrinkage, autogenous shrinkage, and drying shrinkage throughout the entire process at multiple scales, resulting in a significant improvement in crack resistance.

[0031] In summary, this application, through raw material compounding, ensures safe demolding of lightweight ceramsite concrete within 2-4 hours while significantly reducing the risk of alkali-aggregate reaction and shrinkage cracking, achieving both high production efficiency and high reliability. The functions of each component in this application are as follows: Fly ash provides a stable source of active SiO2 and Al2O3, which participate in the geological polymerization reaction to generate aluminosilicate gel (NASH), forming a long-term strength and durability skeleton; Slag powder provides CaO and active SiO2, which participate in the geological polymerization reaction to generate CASH gel and NASH gel, which is a key guarantee for early strength development. However, if the slag ratio is too low, the calcium content of the system is insufficient, the early reaction is slow, and the demolding strength development is slow. If the slag ratio is too high, the reaction is too violent, the chemical shrinkage of the system increases, and the early heat release is concentrated, which increases the temperature stress and exacerbates the risk of cracking and damages the long-term volume stability. Silicate cement clinker powder provides more highly active CaO, which rapidly hydrates the clinker to form CSH gel, providing nucleation sites and accelerating the geopolymerization process. This significantly shortens the setting time and forms early strength, facilitating rapid demolding. Simultaneously, the generated CSH gel interweaves and fills with the geopolymer gel (NASH), jointly constructing a denser and more stable composite cementitious structure. CSH gel possesses good volume stability, effectively compensating for the chemical shrinkage caused by the geopolymerization reaction. If the proportion of silicate clinker powder is too high, excessive CaO hydration will release heat, increasing temperature stress and shrinkage, increasing the risk of cracking, and potentially triggering alkali-aggregate reaction. If the proportion is too low, there will be insufficient calcium source, less CSH gel formation, and a slow geopolymerization reaction, leading to prolonged setting time, reduced early strength, and difficulty in achieving rapid demolding. Alkali-aggregate reaction inhibitors can effectively block OH ions and water from penetrating further into the pore solution, thereby inhibiting the further dissolution and reaction of active aggregates and suppressing the alkali-silica reaction (ASR) from the root of the chemical reaction. However, if the dosage is too low, the inhibition effect is insufficient and the ASR expansion rate may exceed the safety limit (0.10%). If the dosage is too high, it will have a slight inhibitory effect on early strength and is uneconomical. The internal curing material is a pre-absorbent saturated porous material. In the early stage of hardening, when the internal moisture is consumed, the stored moisture is slowly released, achieving "self-humidification". It can maintain a high humidity environment in the capillary pores inside the concrete for a long time, significantly weakening the self-drying and drying shrinkage effects. It is a key physical means to solve the early shrinkage cracking of geopolymer concrete. If the dosage of internal curing material is too low, the internal curing water storage is insufficient, and the shrinkage compensation effect is not obvious. If the dosage of internal curing material is too high, too many additional pores are introduced, which may have a negative impact on the final strength and durability of the concrete. Compensating shrinkage material, as an expansive agent, can provide controllable chemical expansion force. Its delayed hydration characteristics can produce moderate expansion in the middle and late stages of hardening, accurately offsetting the tensile stress generated by chemical shrinkage and drying shrinkage in the geopolymer system. It is a core component to ensure long-term volume stability. When the amount of compensating shrinkage material is insufficient, the expansion is insufficient to compensate for the shrinkage. When the amount of compensating shrinkage material is too high, it may lead to excessive expansion or later strength reduction. The crack-resistant fiber is a coarse polypropylene fiber that bridges microcracks and disperses stress. During the plastic stage and early hardening stage of concrete, it can effectively prevent the generation and development of cracks. Together with internal curing and expansion agent, it forms a triple crack-resistant defense line of crack prevention, shrinkage reduction and compensation.

[0032] In some embodiments, the fly ash residue on a 45μm sieve is ≤12%; the blast furnace slag is S95 grade or higher slag powder with a specific surface area ≥400 m². 2 / kg; Specific surface area of ​​silicate cement clinker powder ≥350 m² 2 / kg.

[0033] In this embodiment, fly ash with a 45μm sieve residue of ≤12% is classified as Grade I fly ash, which has high activity and is beneficial to reaction activity and system stability; S95 grade and above slag powder (specific surface area ≥400 m²) 2 ( / kg) High activity, promotes rapid reaction, accelerates early strength development, and facilitates rapid demolding; suitable for applications with a specific surface area ≥350 m² 2 / kg of silicate clinker powder, its high fineness enhances early reaction activity and promotes rapid coagulation.

[0034] In some embodiments, the alkaline activator is a mixed solution of water glass and sodium hydroxide, and the modulus of the alkaline activator is 1.4-1.6.

[0035] In this embodiment, the molar ratio of SiO2 to Na2O is 1.4-1.6. Within this range, the degree of silicate polymerization is moderate, which can ensure a sufficient reaction rate to meet the early strength requirements, and can also form a more stable geopolymer network, thus balancing early strength and long-term performance.

[0036] In some embodiments, the water glass is an industrial sodium silicate aqueous solution with a modulus of 2.8-3.3; the sodium hydroxide is industrial-grade sodium hydroxide with a purity of ≥98%.

[0037] In some embodiments, the alkali-aggregate reaction inhibitor is lithium carbonate and / or lithium hydroxide.

[0038] In this embodiment, the alkali-aggregate reaction inhibitor is a lithium salt, compared to Na... + K + Li + It can preferentially react with the active silica in the aggregate to form a non-expanding gel (lithium-silicic acid gel). The resulting lithium-silicon compound protective film is extremely dense and can effectively block OH ions and water in the pore solution from continuing to penetrate inward, thereby inhibiting further dissolution and reaction of the active aggregate and inhibiting the alkali-silicic acid reaction (ASR) from the root of the chemical reaction.

[0039] In some embodiments, the ceramsite aggregate has a bulk density of 700~800 kg / m³. 3 It is composed of 5-10mm ceramsite and 0-5mm ceramsite sand in a mass ratio of 1:(1.2-1.4).

[0040] In some embodiments, the high-efficiency water-reducing agent is a naphthalene-based water-reducing agent with a water reduction rate of ≥25%.

[0041] In some embodiments, the internal curing material is pre-water-saturated lightweight porous ceramic sand or zeolite powder with a particle size of 0.3~1.0 mm.

[0042] In some embodiments, the crack-resistant fiber is a coarse polypropylene fiber with a length of 12-19 mm.

[0043] In some embodiments, the shrinkage-compensating material is a calcium sulfoaluminate or calcium oxide-based expansion agent.

[0044] This application provides a method for preparing lightweight expanded clay concrete with high durability and rapid demolding capability, comprising the following steps: An activator solution is obtained by mixing an alkaline activator with an alkali-aggregate reaction inhibitor and then aging the mixture. Fly ash, blast furnace slag, silicate cement clinker powder, and ceramsite aggregate are mixed and then dry-mixed to obtain a mixture. The high-efficiency water-reducing agent and shrinkage-compensating material are dissolved, then mixed with the activator solution, and finally the internal curing material is added to obtain the mixture. Add the liquid to the mixture and perform wet mixing. Then add the crack-resistant fiber to obtain the dry-hard concrete mixture. Lightweight expanded clay concrete is obtained by molding, demolding, and curing the dry-hard concrete mixture.

[0045] Specifically, the preparation method of high-durability, quick-release lightweight ceramsite concrete is as follows: S1. Dissolve solid sodium hydroxide in 40% to 60% of the total mass of the mixing water to prepare a sodium hydroxide solution with a mass fraction of 25% to 45%. After cooling to room temperature, mix with water glass with a modulus of 2.8 to 3.3 and adjust the modulus of the mixed solution to 1.4 to 1.6. Then add an alkali-aggregate reaction inhibitor and mechanically stir the mixed solution at 20 to 25°C for 10 to 15 minutes. Then let it stand and age for 6 to 12 hours to obtain a homogeneous and stable activator solution. In this step, the aging process can bring the degree of polymerization of silicate ions in the activator to a more balanced state, avoiding drastic fluctuations in the reaction rate when mixed with the cementitious material in the later stage, which helps to ensure the stability of product performance. S2. Add all the fly ash, blast furnace slag, silicate cement clinker powder, and ceramsite aggregate into a forced mixer and dry mix for 1-2 minutes to fully and evenly disperse the solid components and obtain a mixture. S3. Dissolve the high-efficiency water-reducing agent and shrinkage compensation material in the remaining mixing water, stir until completely dissolved, then mix evenly with the activator solution prepared in step S1. Finally, slowly add the inner curing material and stir gently to disperse it evenly in the liquid, avoiding excessive particle breakage, and form a mixture. S4. Add the mixture prepared in step S3 to the dry mixture in step S2 at once, wet mix for 3-5 minutes to make the flowing slurry evenly coat the surface of the aggregate, then add the crack-resistant fiber and continue mixing for 2-3 minutes until a dry hard concrete mixture with uniform color, no lumps and slump controlled in the range of 10-30mm is obtained. S5. Molding and Demolding: Quickly pour the dry-hardened concrete mixture into the mold and place it on a high-frequency vibration table with a frequency of 50-70Hz. Vibrate for 60-90 seconds to compact the mixture and remove air bubbles. After vibration molding, move the mold to an indoor environment at 20-30℃ and let it stand for 2-4 hours to cure. When the concrete surface has initially hardened, the edges and corners are intact, and there is no permanent indentation when lightly pressed with a finger, it can be safely demolded. S6. Curing: Immediately after demolding, the concrete product is placed in a curing room and cured in a saturated steam environment with a temperature of 80±5℃ and a relative humidity of ≥95% for 6-8 hours to activate the activity of the cementitious material and quickly build up high strength. Then, it is removed and tightly covered with plastic film or sprayed with curing agent at room temperature (15-25℃) for no less than 7 days of moist curing to ensure the continuous hydration or polymerization reaction of the cementitious material, ensuring long-term strength and durability, and finally obtaining a high-durability lightweight ceramsite concrete that can be quickly demolded.

[0046] The following specific embodiments further illustrate this solution.

[0047] Example 1 A high-durability, quick-release lightweight ceramsite concrete comprises the following components by mass fraction: fly ash: 150 kg (Grade 1, 8.8% residue on 45 μm sieve); blast furnace slag: 100 kg (Grade S95, specific surface area 420 m²). 2 / kg); Silicate cement clinker powder: 60kg (specific surface area 380m²) 2 / kg); Alkaline activator: 95kg (mixed solution of water glass and sodium hydroxide with a modulus of 1.5); Alkali-aggregate reaction inhibitor: 2.5kg (lithium carbonate); Mixing water: 42kg; Ceramsite aggregate: 935kg (from a bulk density of 750kg / m³). 3 The mixture consists of 405 kg of low-alkali clay ceramsite with an average particle size of 7.5 mm and 530 kg of ceramsite sand with an average particle size of 2.5 mm, in a mass ratio of 1:1.3; 1.2 kg of naphthalene-based high-efficiency water-reducing agent (powder, water reduction rate 28%); 12.5 kg of internal curing material (pre-saturated ceramsite sand with an average particle size of 0.5 mm); 1.8 kg of crack-resistant fiber (15 mm in length); and 12.5 kg of shrinkage-compensating material (calcium sulfoaluminate-based expansion agent).

[0048] The preparation method of high-durability, quick-release lightweight ceramsite concrete is as follows: S1. Dissolve solid sodium hydroxide in 50% of the total mass of the mixing water to prepare a 35% solution. After cooling to room temperature, mix with water glass with a modulus of 3.0 to obtain an alkaline activator. Then add an alkali-aggregate reaction inhibitor. Stir the mixture mechanically at 20°C for 12 minutes, and then let it stand for 8 hours to obtain a homogeneous and stable activator solution. S2. Add all the fly ash, blast furnace slag, silicate cement clinker powder, and ceramsite aggregate into a forced mixer and dry mix for 1.5 minutes to fully and evenly disperse the solid components and obtain a mixture. S3. Dissolve the high-efficiency water-reducing agent and shrinkage compensation material in the remaining mixing water, stir until completely dissolved, then mix evenly with the activator solution prepared in step S1. Finally, slowly add the inner curing material and stir gently to disperse it evenly in the liquid, avoiding excessive particle breakage, and form a mixture. S4. Add the mixture prepared in step S3 to the dry mixture in step S2 at once, wet mix for 4 minutes to make the flowing slurry evenly coat the surface of the aggregate, then add the crack-resistant fiber and continue mixing for 3 minutes until a dry hard concrete mixture with uniform color, no lumps and slump controlled within 20mm is obtained. S5. Molding and Demolding: Quickly pour the dry-hard concrete mixture into the mold and place it on a high-frequency vibration table with a frequency of 60Hz. Vibrate for 75 seconds to compact the mixture and remove air bubbles. After vibration molding, move the mold to an indoor environment at 25℃ and let it stand for 2-4 hours to cure. When the concrete surface has initially hardened, the edges and corners are intact, and there is no permanent indentation when lightly pressed with a finger, it can be safely demolded. S6. Curing: The demolded concrete product is immediately placed in a curing chamber and cured for 7 hours in a saturated steam environment at 80℃ and 95% relative humidity to activate the cementitious material and quickly build up high strength. It is then removed and tightly covered with plastic film at room temperature (20℃) for 7 days of moist curing, finally obtaining a high-durability, quickly demoldable lightweight ceramsite concrete.

[0049] Example 2 A lightweight expanded clay aggregate concrete with high durability and rapid demolding capability is described. All other aspects are the same as in Example 1, except that: fly ash: 150 kg (Grade 1, 8.8% residue on 45μm sieve); blast furnace slag: 50 kg (Grade S95, specific surface area 420 m²). 2 / kg); Silicate cement clinker powder: 50kg (specific surface area 380m²) 2 / kg); Alkaline activator: 90kg (mixed solution of water glass and sodium hydroxide with a modulus of 1.4); Alkali-aggregate reaction inhibitor: 2.5kg (lithium hydroxide); Mixing water: 42kg; Ceramsite aggregate: 940kg (from a bulk density of 750kg / m³).3 The mixture consists of 410 kg of low-alkali clay ceramsite with an average particle size of 7.5 mm and 530 kg of ceramsite sand with an average particle size of 2.5 mm, in a mass ratio of 1:1.3; internal curing material: 9 kg (pre-saturated ceramsite sand with an average particle size of 0.5 mm); crack-resistant fiber: 1.8 kg (15 mm in length); shrinkage compensation material: 9 kg (calcium oxide-based expanding agent); naphthalene-based high-efficiency water-reducing agent: 1.2 kg (powder, water reduction rate 28%).

[0050] Comparative Example 1 A lightweight expanded clay concrete is the same as in Example 1, except that silicate cement clinker powder is not added. Its weight is made up by fly ash and slag in the original proportion. The other components and proportions are the same as in Example 1.

[0051] Comparative Example 2 A lightweight expanded clay concrete is the same as in Example 1, except that lithium salt inhibitors are not added, and the other components and proportions are the same as in Example 1.

[0052] Comparative Example 3 A lightweight expanded clay concrete is the same as in Example 1, except that no internal curing material, crack-resistant fiber and shrinkage compensation material are added. The other components and proportions are the same as in Example 1.

[0053] Comparative Example 4 A lightweight expanded clay concrete is the same as in Example 1, except that the cementitious material is only fly ash and slag (ratio 1.8:1, total amount 310kg), the activator modulus is increased to 2.0, the alkali content is increased, and lithium salt inhibitors, internal curing materials, fibers and expansion agents are not added.

[0054] Testing and Evaluation Performance tests were conducted on the concrete obtained from different embodiments and comparative examples, and the results are shown in Table 1. The demolding time was defined as the time when the concrete mixture surface was initially hardened, the edges were intact, and no permanent indentation was observed when lightly pressed with a finger. Demolding strength, steam-cured strength, and 28-day compressive strength were tested according to GB / T 50081-2019, "Standard for Test Methods of Physical and Mechanical Properties of Concrete". Alkali-aggregate reaction expansion rate and 28-day drying shrinkage rate were tested according to GB / T 50082-2009, "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete".

[0055] Table 1 Test Results

[0056] The above results indicate that in Example 2, due to the reduced total amount of cementitious material and slightly lower amounts of internal curing and expanding agent, the early strength was slightly reduced, the demolding time was prolonged, and the shrinkage was slightly increased, but ASR was still effectively suppressed; Comparative Example 1 lacked silicate clinker powder, resulting in insufficient calcium source in the early stage, which led to a prolonged demolding time, significantly reduced demolding strength and strength after steam curing, and increased shrinkage, but lithium salt could still control ASR; Comparative Example 2 did not add lithium salt inhibitor, and the ASR expansion rate increased significantly to a dangerous level, while other properties were basically the same as in Example 1; Comparative Example 3 lacked the crack-resistant system composed of internal curing, fiber, and expanding agent, resulting in a significant increase in drying shrinkage and a slight decrease in strength, but ASR was still under control; Comparative Example 4 simulated existing high-alkali technology, and although demolding was faster, the ASR expansion rate and drying shrinkage were the highest, highlighting potential long-term durability risks.

[0057] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-durability, quick-release lightweight ceramsite concrete, characterized in that, The composition includes the following components by mass fraction: fly ash: 140-180 parts; blast furnace slag: 90-120 parts; silicate cement clinker powder: 40-70 parts; alkaline activator: 80-100 parts; alkali-aggregate reaction inhibitor: 1.5-3.5 parts; mixing water: 35-50 parts; ceramsite aggregate: 900-950 parts. High-efficiency water-reducing agent: 1.0~1.5 parts; Internal curing material: 10~15 parts; Crack-resistant fiber: 0.5~2 parts; Shrinkage compensation material: 12-18 parts.

2. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The fly ash has a 45μm sieve residue of ≤12%; the blast furnace slag is S95 grade or higher slag powder with a specific surface area ≥400 m². 2 / kg; the specific surface area of ​​the silicate cement clinker powder is ≥350 m². 2 / kg.

3. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The alkaline activator is a mixed solution of water glass and sodium hydroxide, and the modulus of the alkaline activator is 1.4-1.

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4. The high-durability, quick-release lightweight ceramsite concrete according to claim 3, characterized in that, The water glass is an industrial sodium silicate aqueous solution with a modulus of 2.8-3.3; the sodium hydroxide is industrial grade sodium hydroxide with a purity of ≥98%.

5. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The alkali-aggregate reaction inhibitor is lithium carbonate and / or lithium hydroxide.

6. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The ceramsite aggregate has a bulk density of 700~800 kg / m³. 3 It is composed of 5-10mm ceramsite and 0-5mm ceramsite sand in a mass ratio of 1:(1.2-1.4).

7. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The high-efficiency water-reducing agent is a naphthalene-based water-reducing agent.

8. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The internal curing material is pre-water-saturated lightweight porous ceramic sand or zeolite powder.

9. The high-durability, quick-release lightweight ceramsite concrete according to claim 1, characterized in that, The crack-resistant fiber is a coarse polypropylene fiber with a length of 12-19 mm; the shrinkage compensation material is a calcium sulfoaluminate or calcium oxide expanding agent.

10. A method for preparing high-durability, rapidly demolded lightweight ceramsite concrete as described in any one of claims 1-9, characterized in that, Includes the following steps: An activator solution is obtained by mixing an alkaline activator with an alkali-aggregate reaction inhibitor and then aging the mixture. The mixture is obtained by dry mixing fly ash, blast furnace slag, silicate cement clinker powder, and ceramsite aggregate. The high-efficiency water-reducing agent and shrinkage-compensating material are dissolved, then mixed with the activator solution, and then the internal curing material is added to obtain the mixture. The mixture is added to the mixture and wet-mixed, and then crack-resistant fibers are added to obtain a dry-hard concrete mixture. The dry-hard concrete mixture is molded, demolded, and cured to obtain the lightweight ceramsite concrete.

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