White belyite sulphoaluminate cementitious material and method for its preparation

Abstract

The present application relates to the field of building materials, and more particularly to a white belite sulphoaluminate cementitious material and a preparation method thereof.The cementitious material comprises, by weight percentage, a setting-adjusting and strength-promoting component 5-20%, functional auxiliaries 10-30%, and the rest being white belite sulphoaluminate clinker; the setting-adjusting and strength-promoting component comprises, by weight fraction, a quick-setting agent 8-13 parts, an early-strength agent 1.5-3 parts, a modified retarder 0.5-2 parts, and a composite expansive agent 1-8 parts; the white high-belite sulphoaluminate cementitious material has the characteristics of fast setting and hardening, can meet the requirement of rapid construction, has high early strength, meets the high-quality requirement of cement-based materials for repair or product, and has continuous growth of late strength, small size deformation, stable structure, low cracking tendency, good durability, and is suitable for harsh environment engineering.

Description

Technical Field

[0001] This invention relates to the field of building materials, and more particularly to a white belite sulfoaluminate cementitious material and its preparation method. Background Technology

[0002] In the field of building materials, cementitious materials are a core component, and their performance directly affects key indicators such as the strength, durability, and construction adaptability of building structures. With the continuous development of the modern construction industry, the functional requirements for cementitious materials are becoming increasingly diversified. They are not only required to have basic bonding capabilities, but also to perform well in terms of setting time control, early strength development, volume stability, and whiteness, so as to adapt to the special requirements of different construction environments and engineering scenarios.

[0003] Traditional cementitious material production processes are energy-intensive and generate significant carbon emissions, consuming large quantities of high-quality natural raw materials such as limestone and bauxite, placing immense pressure on the environment and resources. Furthermore, ordinary cementitious materials have shortcomings in certain performance aspects, such as crack resistance, corrosion resistance, and early strength development, making it difficult to meet the demands of modern engineering construction for high-performance cementitious materials. In fields such as architectural decoration and cement-based handicrafts where appearance is important, the gray color of ordinary cementitious materials limits their application. While white cementitious materials can meet color requirements, they often cannot simultaneously achieve excellent performance in terms of strength, setting time, and durability. Therefore, developing a cementitious material product that possesses both a pleasant white appearance and high performance, while also being low-carbon and environmentally friendly, is of significant practical importance. Summary of the Invention

[0004] To address the aforementioned problems, this invention provides a white belite sulfoaluminate cementitious material and its preparation method. The white high belite sulfoaluminate cementitious material of this invention has rapid setting and hardening characteristics, which can meet the needs of rapid construction. It also has high early strength, which meets the high-quality requirements of repair or product-type cement-based materials. At the same time, its later strength continues to increase, with small dimensional deformation, stable structure, and is not easy to crack. It has good durability and is suitable for engineering in harsh environments.

[0005] The technical solution adopted by the present invention to achieve the above objectives is as follows:

[0006] A white belite sulfoaluminate cementitious material, wherein the cementitious material comprises, by weight percentage, 5-20% setting-regulating and strength-promoting components, 10-30% functional additives, and the remainder being white belite sulfoaluminate clinker; wherein the setting-regulating and strength-promoting components comprise, by weight, 8-13 parts of accelerator, 1.5-3 parts of early-strength agent, 0.5-2 parts of modified retarder, and 1-8 parts of composite expansion agent;

[0007] The preparation method of the modified retarder is as follows:

[0008] Step 1: Calcine basic zinc carbonate at 250-300℃ for 1-2 hours to obtain active ZnO. Then add nano silica, hydroxyethylidene diphosphonic acid, and deionized water. Ultrasonically treat at 40-50℃ for 30-60 minutes and spray dry to obtain porous composite powder.

[0009] Step 2: The composite powder is subjected to fluidized bed coating with an inlet air temperature of 40-45℃, an atomization pressure of 0.2-0.4MPa, a coating liquid spraying rate of 5-10 mL / min, and hot air curing at 38-42℃ for 0.8-1.2h. The powder is then sieved to obtain the final product.

[0010] Preferably, in step 1, the weight ratio of basic zinc carbonate to nano silica, hydroxyethylidene diphosphonic acid, and deionized water is 100:15-35:0.05-0.3:200-300.

[0011] Preferably, in step 2, the coating solution is prepared by dissolving ethyl cellulose in a mixed solvent of ethanol and acetone, wherein the weight ratio of ethyl cellulose to the mixed solvent is 5-8:100, and the volume ratio of ethanol to acetone in the mixed solvent is 3.5-4.5:1.

[0012] Preferably, the preparation method of the composite expanding agent is as follows:

[0013] Step a: Heat PVB powder to 78-82℃, add silane coupling agent KH-550, stir and mix, atomize and spray into a mixture of ethanol and water, react for 15 min, cool to 55-65℃, stir, atomize and spray into magnesium stearate ethanol solution, dry at 60-80℃ for 25-35 min to obtain modified PVB.

[0014] Step b: Activate quicklime by calcining it at 600-800℃ for 0.5-1 hour, then cool it to room temperature. Finally, mix the activated quicklime, anhydrite, modified PVB, and dispersant sodium hexametaphosphate to obtain the final product.

[0015] Preferably, in step a, the ratio of PVB powder, silane coupling agent KH-550, ethanol and water mixture, and magnesium stearate ethanol solution is 100:1-2:12-17:18-23, the weight ratio of ethanol to water in the ethanol and water mixture is 2.5-3.5:1, and the concentration of magnesium stearate ethanol solution is 5%.

[0016] Preferably, in step b, the weight ratio of activated quicklime, anhydrite, modified PVB, and sodium hexametaphosphate is 0.5-3:2-6:1-3:0.1-0.5.

[0017] Preferably, the quick-setting agent is a mixture of anhydrite and aluminum sulfate, with a weight ratio of 1.5-4:1.

[0018] Preferably, the early strength agent is lithium carbonate.

[0019] Preferably, the white Belite sulfoaluminate clinker comprises the following components by weight percentage: 35-48% dicalcium silicate, 22-38% anhydrous calcium sulfoaluminate, 12-25% calcium sulfate, 0.5-8% free calcium oxide, and 0.5-2.8% tetracalcium aluminoferrite. 0.1-0.5%, with the balance being unavoidable impurities.

[0020] The above-mentioned method for preparing white belite sulfoaluminate cementitious material involves mixing white belite sulfoaluminate clinker with the settling and strength-promoting components and functional additives until homogeneous.

[0021] The present invention has the following beneficial effects:

[0022] The white belite sulfoaluminate cementitious material of this invention is mainly composed of white belite sulfoaluminate clinker. Belite hydrates slowly but has high later-stage strength and low heat of hydration; sulfoaluminate provides early strength and rapid hardening characteristics. This combination has advantages such as rapid hardening and early strength, micro-expansion, low alkalinity, and corrosion resistance, meeting specific engineering requirements. In the setting and strength-promoting components, the accelerator (anhydrite + aluminum sulfate) contains anhydrite. Provides sulfate ions, aluminum sulfate It provides aluminum and sulfate ions, which together rapidly promote the formation of calcium sulfoaluminate (such as ettringite), achieving rapid setting and hardening. The ratio of aluminum to sulfate ions (1.5-4:1) can adjust the setting time (initial setting <30 min), avoiding the later strength reduction caused by excessive accelerator. Lithium carbonate, an early strength accelerator, significantly accelerates the hydration of sulfoaluminate and dicalcium silicate, greatly improving early strength with minimal impact on whiteness. The modified retarder is porous. The composite carrier loads hydroxyethylidene diphosphonic acid (HEDP), achieving controlled retardation through slow-release HEDP, thus solving the problem of excessively rapid setting caused by accelerators and early-strength agents. ZnO can also participate in hydration to generate zincates, enhancing durability. The composite expansive agent generates expansive crystals (such as ettringite and calcium hydroxide) through chemical reactions, counteracting the drying shrinkage and thermal shrinkage during the concrete setting and hardening process, preventing cracking. The expansion products fill the pores, enhancing the internal density of the concrete and improving its waterproof and seepage-proof performance.

[0023] The modified retarder, obtained by calcining basic zinc carbonate to generate active ZnO with a high specific surface area, and nano-silica filling the pores to form a three-dimensional network structure, utilizes hydroxyethylidene diphosphonic acid (HEDP) to provide phosphonic acid groups. Through the synergistic effect of these three components, the phosphonic acid groups of hydroxyethylidene diphosphonic acid... Combined, it inhibits the hydration of tricalcium aluminate to form ettringite, thus delaying the rapid setting of the slurry to a certain extent; the porous structure adsorbs... ⁺ and slows down its diffusion, reducing the gel formation rate; ZnO dissolves slowly in an alkaline environment, releasing and The coating stabilizes the slurry pH and delays the hydration of silicate minerals. Ethyl cellulose coating forms a semi-permeable membrane, allowing water to slowly penetrate the core through osmosis, dissolving the retarding components and prolonging the retarding effect. Early coating delays the hydration of HEDP... Release is achieved by avoiding excessively rapid inhibition of hydration; in the mid-to-late stages, as the coating dissolves, a sustained-release effect is achieved. It promotes gel structure densification, enhances later strength, and achieves "slow coagulation in the early stage and strong coagulation in the later stage".

[0024] Furthermore, traditional expanding agents (such as quicklime alone) expand prematurely and violently, easily damaging the structure during the plastic phase. The composite expanding agent of this invention uses modified PVB as a coating material, subjecting PVB powder to dual modification treatment (silane coupling agent improves compatibility with inorganic materials, magnesium stearate improves dispersibility and hydrophobicity), making it a high-performance coating material that activates the materials (quicklime + anhydrite). The quicklime (CaO) hydrates to form… It expands, but the reaction is violent and difficult to control; anhydrite The expansion is caused by the participation of quicklime in the formation of ettringite. Calcination and activation enhance the reactivity of quicklime. Coating activated quicklime particles with modified PVB creates a physical barrier, delaying the contact between water and quicklime, thus delaying the expansion. This ensures that expansion mainly occurs after the cement paste has reached a certain strength (after the plastic stage), avoiding early disordered expansion that could lead to structural damage. Simultaneously, the relatively slow dissolution of anhydrite provides a continuous source of sulfate, which continues to form ettringite with the aluminum phase during later hydration, resulting in compensatory expansion. Dispersant (sodium hexametaphosphate): ensures uniform dispersion of all components in the system, prevents agglomeration, and ensures stable performance.

[0025] In the setting and strength-promoting components, the accelerator promotes the rapid hydration of calcium sulfoaluminate, resulting in the explosive formation of ettringite crystal framework, which lays the foundation for early strength, but may lead to "flash setting" (instantaneous loss of fluidity). The modified retarder, an ethyl cellulose coating layer, physically prevents water from contacting the internal retarding components. Initially, a small amount of HEDP infiltrates into the liquid phase and chelates. This process inhibits the uncontrolled growth of ettringite, achieving a controllable initial setting time and maintaining workability. In the early hardening stage, the accelerator activates belite hydration, generating CSH gel to fill the pores of ettringite, significantly improving density and strength. As the modified retarder gradually dissolves its coating layer, HEDP is continuously released, inhibiting excessive ettringite growth and causing it to form fine, uniform crystals, preventing a loose structure. The composite expansion agent PVB-coated quicklime particles remain inert, and the hydrophobic film prevents water from contacting CaO. The slow dissolution of anhydrite provides the necessary conditions for the later expansion of ettringite. Reserves. During the mid-term development stage, rising slurry temperature and an alkaline environment cause the PVB membrane to swell / rupture, leading to water contact activation and CaO formation. Expansion occurs, and anhydrite provides Supports the continuous formation of ettringite. In the long-term stable phase, anhydrite supports the long-term formation of ettringite (compensating for shrinkage). Carbonization It expands slightly and enhances durability.

[0026] The white high-belite sulfoaluminate cementitious material of this invention exhibits rapid setting and hardening characteristics, with an initial setting time of 15-25 minutes and a final setting time of 25-45 minutes, meeting the requirements for rapid construction. It possesses high early strength, with a compressive strength exceeding 12 MPa after 1 hour, meeting the high-quality requirements of cement-based materials for repair or finished products. The later-stage strength of this cementitious material and the materials prepared from it continues to increase, with a compressive strength exceeding 70 MPa after 28 days. It exhibits minimal dimensional deformation, with a volume change rate only 8%-13% of that of white silicate cement, effectively preventing cracking, improving structural stability, and enhancing durability. It is suitable for engineering projects in harsh environments. It also boasts high whiteness, with a Hunter whiteness of 80-95, meeting decorative requirements.

[0027] The preparation method of this invention is simple, efficient, highly repeatable, and produces stable product quality, making it suitable for industrial production. Detailed Implementation

[0028] The technical solutions in the embodiments of this application will be clearly and completely described below with reference to the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0029] All raw materials used in the following examples are commercially available products. Functional excipients include: ultrafine calcined kaolin, 200 mesh, from Lingshou County Chengjiang Mining Processing Plant; basic zinc carbonate, 99% purity, from Watson; nano-silica, specific surface area 200㎡ / g, particle size 20nm, from Baoket; PVB powder, 99% effective ingredient content, from Jibin Chemical; quicklime, 200mm size, from Aogao; and anhydrite, 99% purity, from Mingzhe.

[0030] Example 1

[0031] A white belite sulfoaluminate cementitious material, characterized in that, by weight percentage, the cementitious material comprises 12% setting and strength-promoting components, 20% functional auxiliary material calcined kaolin, and the remainder is white belite sulfoaluminate clinker, wherein the white belite sulfoaluminate clinker comprises the following components by weight percentage: 42% dicalcium silicate, 30% anhydrous calcium sulfoaluminate, 18% calcium sulfate, 4% free calcium oxide, and 1.5% tetracalcium aluminoferrite. 0.3%, with the balance being unavoidable impurities.

[0032] The setting and strength-promoting components include, by weight, 10 parts of accelerator, 3 parts of early-strength agent, 1.5 parts of modified retarder, and 6 parts of composite expansion agent; the accelerator is a mixture of anhydrite and aluminum sulfate in a weight ratio of 2.5:1, and the early-strength agent is lithium carbonate.

[0033] The preparation method of the modified retarder is as follows:

[0034] Step 1: Calcine basic zinc carbonate at 280℃ for 1.5h to obtain active ZnO, then add nano silica, hydroxyethylidene diphosphonic acid, and deionized water, sonicate at 45℃ for 45min, and spray dry (inlet 185℃, outlet 80℃) to obtain porous composite powder; the weight ratio of basic zinc carbonate to nano silica, hydroxyethylidene diphosphonic acid, and deionized water is 100:22:0.15:250;

[0035] Step 2: The composite powder is subjected to fluidized bed coating with an inlet air temperature of 42℃, an atomization pressure of 0.3MPa, a coating liquid spraying rate of 8mL / min, and hot air curing at 40℃ for 1h. The coating is then passed through a 100-mesh sieve to obtain the final product. The coating liquid is prepared by dissolving ethyl cellulose in a mixed solvent of ethanol and acetone, with a weight ratio of ethyl cellulose to the mixed solvent of 7:100 and a volume ratio of ethanol to acetone of 4:1 in the mixed solvent.

[0036] The preparation method of the composite expanding agent is as follows:

[0037] Step a: Heat PVB powder to 78℃, add silane coupling agent KH-550, stir and mix at 500 rpm for 10 min, then atomize and spray into a mixture of ethanol and water (atomization pressure 0.15 MPa, spraying speed 5 mL / min), continue the reaction for 15 min, cool to 65℃, atomize and spray into a magnesium stearate ethanol solution at 400 rpm (spraying speed 0.8 L / min), and dry at 80℃ for 25 min to obtain modified PVB; the ratio of PVB powder, silane coupling agent KH-550, ethanol and water mixture, and magnesium stearate ethanol solution is 100:1.5:15:20, the weight ratio of ethanol to water in the ethanol and water mixture is 3:1, and the concentration of magnesium stearate ethanol solution is 5%;

[0038] Step b: Activate quicklime by calcining it at 700℃ for 0.8 hours, then rapidly cool it to room temperature. Then, mix the activated quicklime, anhydrite, modified PVB, and dispersant sodium hexametaphosphate at 600 rpm to obtain the final product. The weight ratio of the activated quicklime, anhydrite, modified PVB, and sodium hexametaphosphate is 2:4:2:0.3.

[0039] The preparation method of the above-mentioned white belite sulfoaluminate cementitious material is as follows: First, the white belite sulfoaluminate clinker is ground. Then, the quick-setting agent, early-strength agent, modified retarder, and composite expansion agent are dry-mixed evenly to obtain a setting-regulating and strength-promoting component. Then, the three components of the white belite sulfoaluminate clinker setting-regulating and strength-promoting component and functional auxiliary materials are placed in a mixer and dry-mixed at 350 rpm for 15 minutes until evenly mixed to obtain the final product.

[0040] Example 2

[0041] A white belite sulfoaluminate cementitious material, characterized in that, by weight percentage, the cementitious material comprises 20% setting and strength-promoting components, 15% functional additives, and the remainder being white belite sulfoaluminate clinker; the white belite sulfoaluminate clinker comprises, by weight percentage, the following components: 48% dicalcium silicate, 22% anhydrous calcium sulfoaluminate, 25% calcium sulfate, 0.5% free calcium oxide, and 2.8% tetracalcium aluminoferrite. 0.5%, with the balance being unavoidable impurities;

[0042] The setting and strength-promoting components include, by weight, 8 parts of accelerator, 1.5 parts of early strength agent, 0.5 parts of modified retarder, and 8 parts of composite expansion agent; the accelerator is a mixture of anhydrite and aluminum sulfate in a weight ratio of 1.5:1, and the early strength agent is lithium carbonate.

[0043] The preparation method of the modified retarder is as follows:

[0044] Step 1: Calcine basic zinc carbonate at 250℃ for 2 hours to obtain active ZnO. Then, add nano-silica, hydroxyethylidene diphosphonic acid, and deionized water, sonicate at 50℃ for 30 minutes, and spray dry (inlet 190℃, outlet 85℃) to obtain porous composite powder. The weight ratio of basic zinc carbonate to nano-silica, hydroxyethylidene diphosphonic acid, and deionized water is 100:35:0.05:300.

[0045] Step 2: The composite powder is subjected to fluidized bed coating with an inlet air temperature of 40℃, an atomization pressure of 0.2MPa, a coating liquid spraying rate of 5mL / min, and hot air curing at 42℃ for 0.8h. The coating is then passed through a 100-mesh sieve to obtain the final product. The coating liquid is prepared by dissolving ethyl cellulose in a mixed solvent of ethanol and acetone, with a weight ratio of ethyl cellulose to the mixed solvent of 5:100 and a volume ratio of ethanol to acetone of 3.5:1 in the mixed solvent.

[0046] The preparation method of the composite expanding agent is as follows:

[0047] Step a: Heat PVB powder to 80℃, add silane coupling agent KH-550, stir and mix at 500 rpm for 10 min, then atomize and spray into a mixture of ethanol and water (atomization pressure 0.15 MPa, spraying speed 5 mL / min), continue the reaction for 15 min, cool to 60℃, atomize and spray into a magnesium stearate ethanol solution at 400 rpm (spraying speed 0.8 L / min), and dry at 70℃ for 30 min to obtain modified PVB; the ratio of PVB powder, silane coupling agent KH-550, ethanol and water mixture, and magnesium stearate ethanol solution is 100:2:12:23, the weight ratio of ethanol to water in the ethanol and water mixture is 2.5:1, and the concentration of magnesium stearate ethanol solution is 5%;

[0048] Step b: Activate quicklime by calcining it at 800℃ for 0.5 hours, then rapidly cool it to room temperature. Then, mix the activated quicklime, anhydrite, modified PVB, and dispersant sodium hexametaphosphate at 500 rpm to obtain the final product. The weight ratio of the activated quicklime, anhydrite, modified PVB, and sodium hexametaphosphate is 0.5:6:1:0.5.

[0049] The preparation method of the above-mentioned white belite sulfoaluminate cementitious material is the same as that in Example 1.

[0050] Example 3

[0051] A white belite sulfoaluminate cementitious material, characterized in that, by weight percentage, the cementitious material comprises 5% setting and strength-promoting components, 10% functional additives, and the remainder being white belite sulfoaluminate clinker. The white belite sulfoaluminate clinker, by weight percentage, comprises the following components: 35% dicalcium silicate, 38% anhydrous calcium sulfoaluminate, 12% calcium sulfate, 8% free calcium oxide, and 0.5% tetracalcium aluminoferrite. 0.1%, with the remainder being unavoidable impurities; the setting and strength-promoting components include, by weight, 13 parts of accelerator, 2 parts of early-strength agent, 2 parts of modified retarder, and 1 part of composite expansion agent; the accelerator is a mixture of anhydrite and aluminum sulfate in a weight ratio of 4:1, and the early-strength agent is lithium carbonate.

[0052] The preparation method of the modified retarder is as follows:

[0053] Step 1: Calcine basic zinc carbonate at 300℃ for 1 hour to obtain active ZnO. Then, add nano-silica, hydroxyethylidene diphosphonic acid, and deionized water, sonicate at 40℃ for 60 minutes, and spray dry (inlet 180℃, outlet 75℃) to obtain porous composite powder. The weight ratio of basic zinc carbonate to nano-silica, hydroxyethylidene diphosphonic acid, and deionized water is 100:15:0.3:200.

[0054] Step 2: The composite powder is subjected to fluidized bed coating with an inlet air temperature of 45℃, an atomization pressure of 0.4MPa, a coating liquid spraying rate of 10mL / min, and hot air curing at 38℃ for 1.2h. The coating is then passed through a 100-mesh sieve to obtain the final product. The coating liquid is prepared by dissolving ethyl cellulose in a mixed solvent of ethanol and acetone, with a weight ratio of ethyl cellulose to the mixed solvent of 8:100 and a volume ratio of ethanol to acetone of 4.5:1 in the mixed solvent.

[0055] The preparation method of the composite expanding agent is as follows:

[0056] Step a, wherein the ratio of PVB powder, silane coupling agent KH-550, ethanol and water mixture, and magnesium stearate ethanol solution is 100:1:17:18, the weight ratio of ethanol to water in the ethanol and water mixture is 3.5:1, and the concentration of magnesium stearate ethanol solution is 5%; the rest is the same as in Example 2.

[0057] Step b: Activate quicklime by calcining it at 600℃ for 1 hour, then rapidly cool it to room temperature. Then, stir and mix the activated quicklime, anhydrite, modified PVB, and dispersant sodium hexametaphosphate at 700 rpm to obtain the final product. The weight ratio of the activated quicklime, anhydrite, modified PVB, and sodium hexametaphosphate is 3:2:3:0.1.

[0058] The preparation method of the above-mentioned white belite sulfoaluminate cementitious material is the same as that in Example 1.

[0059] Example 4

[0060] A white belite sulfoaluminate cementitious material, characterized in that, by weight percentage, the cementitious material comprises 16% setting-regulating and strength-promoting components, 30% functional additives, and the remainder being white belite sulfoaluminate clinker and white belite sulfate clinker as in Example 1; the setting-regulating and strength-promoting components by weight comprise 10 parts of accelerator, 2.5 parts of early-strength agent, 1 part of modified retarder, and 3 parts of composite expansion agent, with the remainder being the same as in Example 1.

[0061] Comparative Example 1

[0062] A white belite sulfoaluminate gelling material, wherein the retarder is HEDP retarder, without modification, and the rest is the same as in Example 1.

[0063] Comparative Example 2

[0064] A white belite sulfoaluminate cementitious material, wherein the expanding agent is activated quicklime and gypsum directly mixed in a weight ratio of 1:2 without modification, and the rest is the same as in Example 1.

[0065] Comparative Example 3

[0066] A white belite sulfoaluminate cementitious material, wherein the retarder is HEDP retarder, the expansion agent is activated quicklime and gypsum directly mixed in a weight ratio of 1:2 without modification, and the rest is the same as in Example 1.

[0067] Comparative Example 4

[0068] A white belite sulfoaluminate cementitious material, in composite expansion, uses only activated quicklime and does not use gypsum, otherwise it is the same as in Example 1.

[0069] Comparative Example 5

[0070] A white belite sulfoaluminate cementitious material, in composite expansion, uses only gypsum and does not use activated quicklime, otherwise it is the same as in Example 1.

[0071] The cementitious materials of Examples 1-4 and Comparative Examples 1-5 were tested: the initial setting time and final setting time were determined according to GB / T 1346-2024 "Test Methods for Standard Consistency Water Requirement, Setting Time and Soundness of Cement"; the compressive strength was tested according to GB / T17671-2021 "Test Methods for Strength of Cement Mortar (ISO Method)" at 1h, 3d and 15d, 28d respectively, and the results are shown in Table 1.

[0072] Table 1. Test Results

[0073]

[0074] As shown in Table 1, the white high-belite sulfoaluminate cementitious material of this invention exhibits rapid setting and hardening characteristics, with an initial setting time of 15-25 minutes and a final setting time of 25-45 minutes, meeting the requirements for rapid construction. It also demonstrates high early strength, with a compressive strength exceeding 12 MPa after 1 hour, meeting the high-quality requirements of cement-based materials for repair or finished products. Furthermore, the later-stage strength of this cementitious material and the materials prepared from it continues to increase, with a compressive strength exceeding 70 MPa after 28 days.

[0075] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0076] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A white belite sulfoaluminate cementitious material, characterized in that, The cementitious material comprises, by weight percentage, 5-20% setting-regulating and strength-promoting components, 10-30% functional additives, and the remainder is white Belite sulfoaluminate clinker. The setting-regulating and strength-promoting components comprise, by weight, 8-13 parts of accelerator, 1.5-3 parts of early-strength agent, 0.5-2 parts of modified retarder, and 1-8 parts of composite expansion agent. The preparation method of the modified retarder is as follows: Step 1: Calcine basic zinc carbonate at 250-300℃ for 1-2 hours to obtain active ZnO. Then add nano silica, hydroxyethylidene diphosphonic acid, and deionized water. Ultrasonically treat at 40-50℃ for 30-60 minutes and spray dry to obtain porous composite powder. Step 2: The composite powder is subjected to fluidized bed coating with an inlet air temperature of 40-45℃, an atomization pressure of 0.2-0.4 MPa, a coating liquid spraying rate of 5-10 mL / min, and hot air curing at 38-42℃ for 0.8-1.2 h. After sieving, the product is obtained. In step 1, the weight ratio of basic zinc carbonate to nano silica, hydroxyethylidene diphosphonic acid, and deionized water is 100:15-35:0.05-0.3:200-300. In step 2, the coating solution is prepared by dissolving ethyl cellulose in a mixed solvent of ethanol and acetone, wherein the weight ratio of ethyl cellulose to the mixed solvent is 5-8:100, and the volume ratio of ethanol to acetone in the mixed solvent is 3.5-4.5:

1.

2. The white belite sulfoaluminate cementitious material according to claim 1, characterized in that, The preparation method of the composite expanding agent is as follows: Step a: Heat PVB powder to 78-82℃, add silane coupling agent KH-550, stir and mix, atomize and spray into a mixture of ethanol and water, react for 15 min, cool to 55-65℃, stir, atomize and spray into magnesium stearate ethanol solution, dry at 60-80℃ for 25-35 min to obtain modified PVB. Step b: Activate quicklime by calcining it at 600-800℃ for 0.5-1 hour, then cool it to room temperature. Finally, mix the activated quicklime, anhydrite, modified PVB, and dispersant sodium hexametaphosphate to obtain the final product.

3. The white belite sulfoaluminate cementitious material according to claim 2, characterized in that, In step a, the ratio of PVB powder, silane coupling agent KH-550, ethanol and water mixture, and magnesium stearate ethanol solution is 100:1-2:12-17:18-23, the weight ratio of ethanol to water in the ethanol and water mixture is 2.5-3.5:1, and the concentration of magnesium stearate ethanol solution is 5%.

4. The white belite sulfoaluminate cementitious material according to claim 2, characterized in that, In step b, the weight ratio of activated quicklime, anhydrite, modified PVB, and sodium hexametaphosphate is 0.5-3:2-6:1-3:0.1-0.

5.

5. The white belite sulfoaluminate cementitious material according to claim 1, characterized in that, The quick-setting agent is a mixture of anhydrite and aluminum sulfate, with a weight ratio of 1.5-4:

1.

6. The white belite sulfoaluminate cementitious material according to claim 1, characterized in that, The early strength agent is lithium carbonate.

7. The white belite sulfoaluminate cementitious material according to claim 1, characterized in that, The white Belite sulfoaluminate clinker comprises the following components by weight percentage: 35-48% dicalcium silicate, 22-38% anhydrous calcium sulfoaluminate, 12-25% calcium sulfate, 0.5-8% free calcium oxide, and 0.5-2.8% tetracalcium aluminoferrite. 0.1-0.5%, with the balance being unavoidable impurities.

8. The method for preparing the white belite sulfoaluminate cementitious material according to any one of claims 1-7, characterized in that, The white Belite sulfoaluminate clinker is mixed with the aforementioned setting and strengthening components and functional additives to obtain the final product.

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