A method for preparing a pre-carbonated directional nucleating agent, carbonation-resistant super-sulfated cement

Abstract

The application relates to the field of cement-based building materials, and particularly discloses a preparation method of a pre-carbonization directional nucleating agent and anti-carbonization supersulfated cement, which comprises the following steps: (1) grinding a mixture formed by a one-dimensional chain-shaped or porous inorganic carrier, water and a carboxyl confining agent to obtain an active carrier dispersion slurry; (2) mixing the active carrier dispersion slurry with an active calcium component, grinding, then performing normal pressure-negative pressure alternate immersion treatment, and obtaining an active calcium loaded carrier slurry after the treatment; (3) adding a dendritic amine group component and an imidazole group inducing component into the active calcium loaded carrier slurry, then adjusting the system to be alkaline and stirring to react, drying the obtained slurry and preparing a powder, and the preparation is completed. 2+ The nucleating agent can capture CO2, confine the release of Ca2+ and induce the uniform nucleation of nano / micron-sized calcium carbonate in the carbonization process, and the long-term carbonization resistance of the supersulfated cement is improved.

Description

Technical Field

[0001] This invention relates to the field of cement-based building materials, specifically to a pre-carbonization directional nucleating agent and a method for preparing carbonization-resistant hypersulfate cement. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] Supersulfate cement is a type of low-carbon cementitious material formed primarily from granulated blast furnace slag, activated by sulfates and a small amount of alkaline components. This type of material boasts advantages such as low clinker consumption, high solid waste utilization, and low carbon emissions, making it highly valuable in low-carbon building materials and industrial solid waste resource utilization. However, supersulfate cement has a low content of ordinary silicate clinker, and its alkali reserve and calcium hydroxide content are typically lower than those of ordinary silicate cement systems. In the atmospheric environment, carbon dioxide easily enters the interior of supersulfate cement through capillary pores and reacts with hydration products such as ettringite, CSH, or CASH gel to produce calcium carbonate, gypsum, and other products. This leads to a decrease in pH, localized neutralization, increased porosity, and a decline in strength and durability. Therefore, insufficient resistance to carbonation becomes a key issue restricting the application of supersulfate cement.

[0004] Furthermore, the early dissolution and hydration reactions of slag in supersulfate cement are relatively slow, especially under conditions of high desulfurization gypsum and low clinker content, often resulting in problems such as prolonged setting time and insufficient early strength. Existing technologies mostly improve early performance by increasing the amount of alkaline activator, adding clinker, or adding nano-inorganic fillers. However, increasing the amount of alkaline activator or clinker weakens the material's low-carbon advantage, while the added nano-inorganic fillers mainly play a role in ordinary filling and heterogeneous nucleation, making it difficult to effectively solve the carbonization problem caused by later CO2 intrusion. Summary of the Invention

[0005] This invention provides a pre-carbonation directional nucleating agent and a method for preparing carbonation-resistant hypersulfate cement. The nucleating agent more efficiently captures CO2 and releases Ca2+ during the pre-carbonation process. 2+ This process induces uniform nucleation of nano / micro-sized calcium carbonate, thereby improving the early pre-carbonation and mineralization enhancement and long-term carbonation resistance of supersulfate cement. Specifically, the technical solution of this invention is as follows.

[0006] In a first aspect, the present invention provides a method for preparing a pre-carbonized directional nucleating agent, comprising the following steps: (1) Grind the mixture of one-dimensional chain or porous inorganic carrier, water and carboxyl confinement agent to obtain an active carrier dispersion slurry for later use.

[0007] (2) The active carrier dispersion slurry is mixed with the active calcium component and then ground. Then, it is subjected to alternating impregnation treatment under normal pressure and negative pressure. After completion, the active calcium loaded carrier slurry is obtained for later use.

[0008] (3) Dendritic amine components and imidazole inducing components are added to the active calcium-supported slurry, and then the system is adjusted to alkaline and stirred for reaction. After completion, the resulting slurry is dried and made into powder to obtain the pre-carbonized directional nucleating agent.

[0009] Further, in step (1), the ratio of the one-dimensional chain-like or porous inorganic support to the carboxyl confinement agent is 10-35 parts by weight: 0.05-2.0 parts by weight. Optionally, the solid content of the mixture is 30-40 wt.%.

[0010] Further, in step (1), the one-dimensional chain-like or porous inorganic carrier includes one or more of sepiolite, attapulgite, diatomite, bentonite, etc.

[0011] Further, in step (1), the carboxyl confinement agent includes one or more of polyaspartic acid, polyacrylic acid, citrate, tartrate, etc. This invention utilizes the above-mentioned carboxyl confinement agent to form a complexable Ca complex on the surface of the inorganic carrier. 2+ The interface layer helps prevent the disordered migration of active calcium components on the surface of the inorganic carrier during subsequent preparation processes.

[0012] Further, in step (2), the active calcium component is added in a ratio of 40~75 parts by weight to 10~35 parts by weight of one-dimensional chain-like or porous inorganic carrier.

[0013] Further, in step (2), the active calcium component includes one or more of the following: carbide slag powder, calcium oxide, steel slag powder, recycled concrete powder, etc.

[0014] Furthermore, in steps (1) and (2), the grinding time is 25-35 minutes. In step (1), after grinding, the pores, grooves, interlayer structure or chain-like overlapping structure of the one-dimensional chain-like or porous inorganic carrier are fully exposed, providing a spatial basis for the subsequent loading of active calcium components and the entry of CO2 during pre-carbonization and mineralization curing.

[0015] Further, in step (2), the alternating impregnation treatment method includes: first stirring under normal pressure for 5-20 minutes, then letting it stand under negative pressure of -0.02 to -0.08 MPa for 5-30 minutes, repeating the above operation 1-3 times, so that the active calcium component and the dissolved Ca... 2+ It fully penetrates the interior of the one-dimensional chain-like or porous inorganic carrier to form confined active calcium sites.

[0016] Further, in step (3), the dendritic amine component and the imidazole inducing component are added in the following proportions: dendritic amine component: imidazole inducing component: carboxyl confinement agent = 0.1~3 parts by weight: 0.05~2 parts by weight: 0.05~2 parts by weight.

[0017] Further, in step (3), the dendritic amine component includes one or more of the following: hyperbranched polyethyleneimine, chitosan, polylysine, and aminated lignin.

[0018] Further, in step (3), the imidazole-inducing component includes one or more of histidine, polyvinylimidazole, etc. This invention utilizes the dendritic amine component and the imidazole-inducing component to promote local CO2 enrichment during the pre-carbonization process, and synergistically induces the refinement and nucleation of calcium carbonate with the carboxyl confinement agent.

[0019] Further, in step (3), the alkalinity is pH=10~12. Optionally, at least one of calcium hydroxide slurry, carbide slag slurry, etc., is used to adjust the pH.

[0020] Further, in step (3), the stirring reaction time is 20~90 min, so that the dendritic amine component and the imidazole inducing component form a CO2 enrichment inducing interface containing amine and imidazole groups on the surface of the active calcium support.

[0021] Furthermore, in step (3), the particle size of the pre-carbonized directional nucleating agent is 5~100μm.

[0022] Secondly, the present invention provides a method for preparing carbonization-resistant hypersulfate cement, comprising the following steps: using slag powder, gypsum powder, aluminate cement, the pre-carbonization directional nucleating agent of the present invention, and water-reducing agent as raw materials, mixing them with mixing water, and then placing them in a CO2 atmosphere for pre-carbonization and mineralization curing, thereby obtaining the carbonization-resistant hypersulfate cement.

[0023] Further, the proportions of each component in the raw materials are as follows: 45-70 parts by weight of slag powder, 20-45 parts by weight of gypsum powder, 5-15 parts by weight of aluminate cement, 2-10 parts by weight of the pre-carbonization directional nucleating agent, and 0.1-1.0 parts by weight of water-reducing agent. Optionally, the mixing water is added at a water-binder ratio of 0.32-0.45:1, where the "binder" is the sum of the slag powder, gypsum powder, aluminate cement, and pre-carbonization directional nucleating agent.

[0024] Furthermore, the curing process begins 0 to 4 hours after the raw materials are mixed with the mixing water.

[0025] Furthermore, in the pre-carbonization and mineralization curing process, the CO2 volume fraction is 1-10%, the curing time is 0.5-6 hours, the relative humidity is 55-85%, and the temperature is 20-40℃.

[0026] Compared with the prior art, the present invention has at least the following beneficial technical effects: This invention provides an early, mild, and controllable CO2 pre-carbonization mineralization treatment for hypersulfate cement. This allows CO2 to preferentially participate in beneficial mineralization reactions during the early stages of cement hardening, rather than randomly entering the cement body through erosion in later service life. To further enhance the reaction efficiency of CO2 with active calcium during the pre-carbonization mineralization process and induce the dispersion and formation of nano / micro-sized CaCO3, this invention further constructs a pre-carbonization directional nucleating agent. This agent efficiently captures CO2 entering the interior of the hypersulfate cement during the pre-carbonization mineralization treatment while simultaneously releasing CaCO3 within a confined space. 2+ This invention induces uniform nucleation of nano / micro-sized calcium carbonate, pre-generating uniformly dispersed nano / micro-sized calcium carbonate to effectively block capillary channels and improve the density of the cement matrix, thereby simultaneously improving the early strength and later carbonation resistance of supersulfate cement. To this end, the present invention first loads a carboxyl confinement agent onto a one-dimensional chain-like or porous inorganic support, thereby forming a carboxyl confinement agent on the surface of the support that can regulate the Ca... 2+ A confined interface layer for migration and enrichment, thereby pre-constructing interfacial immobilization sites for active calcium components and Ca2+. 2+ Near-field enrichment is the basis. Based on this, active calcium components, dendritic amine components, and imidazole-inducing components are further loaded to form a pre-carbonized directional nucleating agent with a special structure of "porous drainage-active calcium confinement-biomimetic induced nucleation". The active calcium component and its dissolved Ca... 2+ The active calcium is confined to the pores, grooves, or interfacial microregions of the carrier and adsorbed and complexed by the carboxyl confining agent, forming active calcium confining sites. The "confinement" includes both spatial and chemical confinement: spatial confinement refers to the dispersion, loading, and positional constraint of the active calcium component by the carrier's pores, grooves, or chain structure; chemical confinement refers to the effect of the carboxyl confining agent on the Ca... 2+The complexing, adsorption, and slow-release effects of the active calcium component, through this dual confinement, prevent it from migrating and agglomerating randomly in the form of ordinary powder or rapidly forming large calcium carbonate precipitates in the porous solution during subsequent pre-carbonization and mineralization curing. Instead, it can release Ca in a relatively dispersed and controllable manner in the near-field region of the carrier. 2+ The dendritic amine component and the imidazole-inducing component are distributed around the active calcium confinement sites, forming a composite induced interface containing carboxyl, amine, and imidazole groups together with the carboxyl confinement agent. The dendritic amine component promotes the adsorption and dissolution of CO2 in the interface region of the nucleating agent of this invention, while the imidazole-inducing component promotes the enrichment of carbonate species formed by CO2 dissolution and transformation near the interface region and participates in regulating the calcium carbonate nucleation process, thereby enabling Ca... 2+ The carbonate species formed by CO2 dissolution and transformation no longer mainly rely on random collisions in the slurry pore solution to react, but instead form near-field coupling reaction regions on the carrier surface, inside the pores, and near the active calcium confinement sites.

[0027] When the nucleating agent of this invention is added to persulfate cement and subjected to controlled CO2 precarbonation and mineralization treatment, CO2 preferentially enters the nucleating agent through the channels and interface regions formed by the one-dimensional chain-like or porous inorganic carrier, and undergoes adsorption, dissolution, and carbonation transformation near the interface formed by the dendritic amine component and the imidazole inducing component. Simultaneously, Ca2+ is released from the active calcium confinement sites. 2+ Under the regulation of carboxyl confinement agents, fine, dispersed nano / micron-sized CaCO3 nuclei are generated in situ by directional binding with carbonate species in the near-field region of the support. This process improves the local contact efficiency between CO2 and active calcium components, inhibits the disordered precipitation of coarse calcium carbonate crystals, and makes the generated CaCO3 more easily distributed near early pores, interface defects, and support channels. The in-situ generated nano / micron-sized CaCO3 can not only serve as a pore-filling phase, pre-blocking the capillary channels formed during the early hardening process of persulfate cement, refining the pore structure and improving matrix density; it can also serve as heterogeneous nucleation sites, providing an interfacial basis for the deposition and interwoven growth of hydration products such as CSH, CASH gel, and ettringite, thereby promoting the formation of early cemented structures and improving early strength. As the hydration and hardening process continues, the CaCO3 filling phase and the hydration products it induces together reduce pore connectivity, making it difficult for CO2 in the subsequent service environment to rapidly penetrate along continuous capillary channels, thereby reducing the risk of deep carbonization and decomposition of hydration products and improving the long-term carbonization resistance of supersulfate cement.

[0028] The controllable CO2 pre-carbonization mineralization treatment of the present invention differs from natural carbonization erosion during long-term service. Its purpose is not to cause deep carbonization and decomposition of hydration products in persulfate cement, but to allow CO2 to preferentially enter and react with the pre-carbonization directional nucleating agent in the persulfate cement during the period when the persulfate cement is not fully hardened and the pore structure is in a controllable stage, so as to form a pore-filling phase and hydration nucleation sites, thereby reducing the risk of continuous external CO2 intrusion and disordered carbonization during the later service process, and improving the carbonization resistance of persulfate cement during long-term service. Attached Figure Description

[0029] The accompanying drawings, which form part of this specification, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. Hereinafter, embodiments of the invention will be described in detail with reference to the accompanying drawings, wherein: Figure 1 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 1 below.

[0030] Figure 2 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 2 below.

[0031] Figure 3 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 3 below.

[0032] Figure 4 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 5 below.

[0033] Figure 5 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 6 below.

[0034] Figure 6 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 7 below.

[0035] Figure 7 The image shows a sample of the pre-carbonized directional nucleating agent prepared in Example 8 below. Detailed Implementation

[0036] The present invention is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Experimental methods in the following embodiments, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of skill in the art. The reagents and raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they shall be used in accordance with conventional methods in the art or as per the product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to the methods of this invention.

[0038] Example 1 1. A method for preparing a pre-carbonized directional nucleating agent, comprising the following steps: (1) Take the following components in the following proportions: 20 parts by weight of one-dimensional chain or porous inorganic carrier (sepiolite powder), 0.6 parts by weight of carboxyl confinement agent (polyaspartic acid), 65 parts by weight of active calcium component (carbide slag), 1 part by weight of dendritic amine component (branched polyethyleneimine, CAS No. 9002-98-6, molecular weight 25000, used in the form of an aqueous solution with a concentration of 50wt.%), and 0.4 parts by weight of imidazole inducing component (histidine).

[0039] (2) The one-dimensional chain-like or porous inorganic carrier, water, and carboxyl confinement agent are mixed and stirred for 20 min to obtain a mixture with a solid content of 35 wt.%. The mixture is then mechanically ground for 30 min to obtain an active carrier dispersion slurry for later use.

[0040] (3) After mixing the active carrier dispersion slurry with the active calcium component, it is first sheared and dispersed at a high speed of 5000 r / min for 10 min, and then ground for 25 min. Then, it is subjected to alternating atmospheric pressure and negative pressure impregnation treatment: first, it is stirred at atmospheric pressure for 10 min, and then it is allowed to stand for 20 min under negative pressure of -0.06 MPa. The above operation is repeated twice. After completion, the active calcium loaded carrier slurry is obtained and ready for use.

[0041] (4) The dendritic amine component and imidazole inducing component were added to the active calcium-supported carrier slurry. Then, the pH of the system was adjusted to 11 with calcium hydroxide slurry. After stirring for 45 min, the mixture was spray-dried (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g., Figure 1 (As shown).

[0042] 2. A method for preparing carbonation-resistant hypersulfate cement, comprising the following steps: (1) Take the following components in the following proportions: 58 parts by weight of granulated blast furnace slag powder, 35 parts by weight of desulfurized gypsum powder, 8 parts by weight of aluminate cement, 4 parts by weight of the precarbonation directional nucleating agent described in this embodiment, and 0.3 parts by weight of polycarboxylate superplasticizer.

[0043] (2) Add the solid components from the above composition to a mixer and dry mix for 5 minutes. Then add the water-reducing agent and 40 parts by weight of mixing water, mix for 3 minutes, and pour into a mold for 2 hours. Then place it in a carbonization box for controlled CO2 pre-carbonization and mineralization curing (CO2 volume fraction in the carbonization box is 3%, relative humidity is 70%, and temperature is 35℃). After 2 hours, standard curing is performed, and supersulfate cement is obtained.

[0044] Performance tests: (1) The compressive strength of specimens prepared in this embodiment and cured to standard age of 1d, 3d, and 28d were tested according to GB / T17671-2021. (2) The carbonation depth of specimens prepared in this embodiment and cured to standard age of 28d was tested according to GB / T50082-2009. (3) The total porosity of specimens prepared in this embodiment and cured to standard age of 28d was tested using mercury intrusion porosimetry. The test results of the above performance indicators are shown in Table 1 below.

[0045] Table 1

[0046] Example 2 1. A method for preparing a pre-carbonized directional nucleating agent, comprising the following steps: (1) Take the following components in the following proportions: 35 parts by weight of one-dimensional chain-like or porous inorganic carrier (attapulgite powder), 2.0 parts by weight of carboxyl confinement agent (polyacrylic acid), 75 parts by weight of active calcium component (steel slag powder), 3.0 parts by weight of dendritic amine component (polylysine), and 2.0 parts by weight of imidazole inducing component (histidine).

[0047] (2) The one-dimensional chain-like or porous inorganic carrier, water, and carboxyl confinement agent are mixed and stirred for 20 min to obtain a mixture with a solid content of 40 wt.%. The mixture is then mechanically ground for 25 min to obtain an active carrier dispersion slurry for later use.

[0048] (3) After mixing the active carrier dispersion slurry with the active calcium component, it is first sheared and dispersed at a high speed of 8000 r / min for 10 min, and then ground for 25 min. Then, it is subjected to alternating atmospheric pressure and negative pressure impregnation treatment: first, it is stirred at atmospheric pressure for 5 min, and then it is allowed to stand for 30 min under negative pressure of -0.02 MPa. The above operation is repeated 3 times. After completion, the active calcium loaded carrier slurry is obtained and ready for use.

[0049] (4) The dendritic amine component and imidazole inducing component were added to the active calcium-supported carrier slurry. Then, the pH of the system was adjusted to 10 with calcium hydroxide slurry. After stirring for 90 min, the mixture was spray-dried (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g., Figure 2 (As shown).

[0050] 2. A method for preparing carbonation-resistant hypersulfate cement, comprising the following steps: (1) Take the following components in the following proportions: 45 parts by weight of granulated blast furnace slag powder, 20 parts by weight of natural gypsum powder, 5 parts by weight of aluminate cement, 2 parts by weight of the pre-carbonized directional nucleating agent described in this embodiment, and 0.1 parts by weight of polycarboxylate superplasticizer.

[0051] (2) Add the solid components from the above composition to a mixer and dry mix for 5 minutes. Then add the water-reducing agent and 23 parts by weight of mixing water, mix for 3 minutes, and pour into a mold. Then immediately place it in a carbonization box for controlled CO2 pre-carbonization and mineralization curing (CO2 volume fraction in the carbonization box is 1%, relative humidity is 85%, and temperature is 20℃). After 6 hours, standard curing is performed, and supersulfate cement is obtained.

[0052] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 2 below.

[0053] Table 2

[0054] Example 3 1. A method for preparing a pre-carbonized directional nucleating agent, comprising the following steps: (1) Take the following components in the following proportions: 10 parts by weight of one-dimensional chain or porous inorganic carrier (diatomaceous earth powder), 0.05 parts by weight of carboxyl confinement agent (sodium tartrate), 40 parts by weight of active calcium component (calcium oxide), 0.1 parts by weight of dendritic amine component (branched polyethyleneimine, CAS No. 9002-98-6, molecular weight 25000, used in the form of an aqueous solution with a concentration of 50wt.%), and 0.05 parts by weight of imidazole inducing component (polyvinylimidazolium).

[0055] (2) The one-dimensional chain-like or porous inorganic carrier, water, and carboxyl confinement agent are mixed and stirred for 20 min to obtain a mixture with a solid content of 30 wt.%. The mixture is then mechanically ground for 35 min to obtain an active carrier dispersion slurry for later use.

[0056] (3) After mixing the active carrier dispersion with the active calcium component, the mixture is first sheared and dispersed at a high speed of 6000 r / min for 10 min, and then ground for 35 min. Subsequently, an alternating atmospheric and negative pressure impregnation treatment is performed: first, stirring at atmospheric pressure for 20 min, and then standing under a negative pressure of -0.08 MPa for 5 min. After completion, an active calcium-supported carrier slurry is obtained for later use.

[0057] (4) The dendritic amine component and imidazole inducing component were added to the active calcium-supported carrier slurry. Then, the pH of the system was adjusted to 12 with carbide slag slurry. After stirring and reacting for 20 min, spray drying was carried out (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g., Figure 3 (As shown).

[0058] 2. A method for preparing carbonation-resistant hypersulfate cement, comprising the following steps: (1) Take the following components in the following proportions: 70 parts by weight of granulated blast furnace slag powder, 45 parts by weight of phosphogypsum powder, 15 parts by weight of aluminate cement, 10 parts by weight of the pre-carbonized directional nucleation agent described in this embodiment, and 1.0 parts by weight of polycarboxylate superplasticizer.

[0059] (2) Add the solid components from the above composition to a mixer and dry mix for 10 minutes. Then add the water-reducing agent and 63 parts by weight of mixing water, mix for 2 minutes, and pour into a mold to form for 4 hours. Then place it in a carbonization box for controlled CO2 pre-carbonization and mineralization curing (CO2 volume fraction in the carbonization box is 10%, relative humidity is 55%, and temperature is 40℃). After 0.5 hours, standard curing is performed, and after completion, supersulfate cement is obtained.

[0060] Performance testing: The performance indicators of the supersulfate cement prepared in this example were tested using the same method as in Example 1 above. The test results are shown in Table 3 below.

[0061] Table 3

[0062] Example 4 A method for preparing carbonation-resistant hypersulfate cement includes the following steps: (1) Take the following components in the following proportions: 58 parts by weight of granulated blast furnace slag powder, 35 parts by weight of desulfurized gypsum powder, 8 parts by weight of aluminate cement, and 0.3 parts by weight of polycarboxylate superplasticizer.

[0063] (2) Add the solid components from the above composition to a mixer and dry mix for 5 minutes. Then add the water-reducing agent and 38.5 parts by weight of mixing water, mix for 3 minutes, and pour into a mold to form for 2 hours. Then place it in a carbonization box for controlled CO2 pre-carbonization and mineralization curing (CO2 volume fraction in the carbonization box is 3%, relative humidity is 70%, and temperature is 35℃). After 2 hours, standard curing is performed, and supersulfate cement is obtained.

[0064] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 4 below.

[0065] Table 4

[0066] Example 5 A method for preparing carbonation-resistant hypersulfate cement is the same as in Example 1 above, except that the pre-carbonation directional nucleating agent in this example is prepared by the following method: (1) Take the following components in the following proportions: 20 parts by weight of one-dimensional chain or porous inorganic carrier (sepiolite powder), 65 parts by weight of active calcium component (carbide slag), 1 part by weight of dendritic amine component (branched polyethyleneimine, CAS No. 9002-98-6, molecular weight 25000, used in the form of an aqueous solution with a concentration of 50wt.%), and 0.4 parts by weight of imidazole inducing component (histidine).

[0067] (2) The one-dimensional chain-like or porous inorganic carrier is mixed with water and stirred for 20 min to obtain a mixture with a solid content of 35 wt.%. The mixture is then mechanically ground for 30 min to obtain an active carrier dispersion slurry for later use.

[0068] (3) After mixing the active carrier dispersion slurry with the active calcium component, it is first sheared and dispersed at a high speed of 5000 r / min for 10 min, and then ground for 25 min. Then, it is subjected to alternating atmospheric pressure and negative pressure impregnation treatment: first, it is stirred at atmospheric pressure for 10 min, and then it is allowed to stand for 20 min under negative pressure of -0.06 MPa. The above operation is repeated twice. After completion, the active calcium loaded carrier slurry is obtained and ready for use.

[0069] (4) The dendritic amine component and imidazole inducing component were added to the active calcium-supported carrier slurry. Then, the pH of the system was adjusted to 11 with calcium hydroxide slurry. After stirring for 45 min, the mixture was spray-dried (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g., Figure 4 (As shown).

[0070] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 5 below.

[0071] Table 5

[0072] Example 6 A method for preparing carbonation-resistant hypersulfate cement is the same as in Example 2 above, except that the pre-carbonation directional nucleating agent in this example is prepared by the following method: (1) Take the following components in the following proportions: 35 parts by weight of one-dimensional chain-like or porous inorganic carrier (attapulgite powder), 2.0 parts by weight of carboxyl confinement agent (polyacrylic acid), 75 parts by weight of active calcium component (steel slag powder), and 2.0 parts by weight of imidazole inducing component (histidine).

[0073] (2) The one-dimensional chain-like or porous inorganic carrier, water, and carboxyl confinement agent are mixed and stirred for 20 min to obtain a mixture with a solid content of 40 wt.%. The mixture is then mechanically ground for 25 min to obtain an active carrier dispersion slurry for later use.

[0074] (3) After mixing the active carrier dispersion slurry with the active calcium component, it is first sheared and dispersed at a high speed of 8000 r / min for 10 min, and then ground for 25 min. Then, it is subjected to alternating atmospheric pressure and negative pressure impregnation treatment: first, it is stirred at atmospheric pressure for 5 min, and then it is allowed to stand for 30 min under negative pressure of -0.02 MPa. The above operation is repeated 3 times. After completion, the active calcium loaded carrier slurry is obtained and ready for use.

[0075] (4) The imidazole-based inducing component was added to the active calcium-supported carrier slurry, and then the pH of the system was adjusted to 10 with calcium hydroxide slurry. After stirring for 90 min, the mixture was spray-dried (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g., Figure 5 (As shown).

[0076] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 6 below.

[0077] Table 6

[0078] Example 7 A method for preparing carbonation-resistant hypersulfate cement is the same as in Example 3 above, except that the pre-carbonation directional nucleating agent in this example is prepared by the following method: (1) Take the following components in the following proportions: 10 parts by weight of one-dimensional chain-like or porous inorganic carrier (diatomaceous earth powder), 0.05 parts by weight of carboxyl confinement agent (sodium tartrate), 40 parts by weight of active calcium component (calcium oxide), and 0.1 parts by weight of dendritic amine component (branched polyethyleneimine, CAS No. 9002-98-6, molecular weight 25000, used in the form of an aqueous solution with a concentration of 50wt.%).

[0079] (2) The one-dimensional chain-like or porous inorganic carrier, water, and carboxyl confinement agent are mixed and stirred for 20 min to obtain a mixture with a solid content of 30 wt.%. The mixture is then mechanically ground for 35 min to obtain an active carrier dispersion slurry for later use.

[0080] (3) After mixing the active carrier dispersion with the active calcium component, the mixture is first sheared and dispersed at a high speed of 6000 r / min for 10 min, and then ground for 35 min. Subsequently, an alternating atmospheric and negative pressure impregnation treatment is performed: first, stirring at atmospheric pressure for 20 min, and then standing under a negative pressure of -0.08 MPa for 5 min. After completion, an active calcium-supported carrier slurry is obtained for later use.

[0081] (4) The dendritic amine component was added to the active calcium-supported carrier slurry, and then the pH of the system was adjusted to 12 with carbide slag slurry. After stirring and reacting for 20 min, spray drying was carried out (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g. Figure 6 (As shown).

[0082] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 7 below.

[0083] Table 7

[0084] Example 8 A method for preparing carbonation-resistant hypersulfate cement is the same as in Example 2 above, except that the pre-carbonation directional nucleating agent in this example is prepared by the following method: (1) Take the following components in the following proportions: 35 parts by weight of calcium carbonate powder, 2.0 parts by weight of carboxyl confinement agent (polyacrylic acid), 75 parts by weight of active calcium component (steel slag powder), 3.0 parts by weight of dendritic amine component (polylysine), and 2.0 parts by weight of imidazole inducing component (histidine).

[0085] (2) The calcium carbonate powder, water, and carboxyl limiting agent are mixed and stirred for 20 min to obtain a mixture with a solid content of 40 wt.%. The mixture is then mechanically ground for 25 min to obtain an active carrier dispersion slurry for later use.

[0086] (3) After mixing the active carrier dispersion slurry with the active calcium component, it is first sheared and dispersed at a high speed of 8000 r / min for 10 min, and then ground for 25 min. Then, it is subjected to alternating atmospheric pressure and negative pressure impregnation treatment: first, it is stirred at atmospheric pressure for 5 min, and then it is allowed to stand for 30 min under negative pressure of -0.02 MPa. The above operation is repeated 3 times. After completion, the active calcium loaded carrier slurry is obtained and ready for use.

[0087] (4) The dendritic amine component and imidazole inducing component were added to the active calcium-supported carrier slurry. Then, the pH of the system was adjusted to 10 with calcium hydroxide slurry. After stirring for 90 min, the mixture was spray-dried (inlet air temperature 190℃, outlet air temperature 90℃) to obtain a pre-carbonized directional nucleating agent with a particle size distribution between 5 and 100 μm (e.g., Figure 7 (As shown).

[0088] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 8 below.

[0089] Table 8

[0090] Example 9 A method for preparing carbonation-resistant hypersulfate cement includes the following steps: (1) Take the following components in the following proportions: 45 parts by weight of granulated blast furnace slag powder, 20 parts by weight of natural gypsum powder, 5 parts by weight of aluminate cement, 2 parts by weight of nano calcium carbonate, and 0.1 parts by weight of polycarboxylate superplasticizer.

[0091] (2) Add the solid components from the above composition to a mixer and dry mix for 5 minutes. Then add the water-reducing agent and 23 parts by weight of mixing water, mix for 3 minutes, and pour into a mold. Then immediately place it in a carbonization box for controlled CO2 pre-carbonization and mineralization curing (CO2 volume fraction in the carbonization box is 1%, relative humidity is 85%, and temperature is 20℃). After 6 hours, standard curing is performed, and supersulfate cement is obtained.

[0092] Performance testing: The performance indicators of the supersulfate cement prepared in this embodiment were tested using the same method as in Example 1 above. The test results are shown in Table 9 below.

[0093] Table 9

[0094] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a pre-carbonized directional nucleating agent, characterized in that, Includes the following steps: (1) Grind the mixture of one-dimensional chain or porous inorganic carrier, water and carboxyl confinement agent to obtain an active carrier dispersion slurry for later use; the ratio of the one-dimensional chain or porous inorganic carrier to the carboxyl confinement agent is 10~35 parts by weight: 0.05~2.0 parts by weight. The one-dimensional chain-like or porous inorganic carrier includes one or more of sepiolite, attapulgite, diatomaceous earth, and bentonite; the carboxyl confinement agent includes one or more of polyaspartic acid, polyacrylic acid, citrate, and tartrate. (2) The active carrier dispersion slurry is mixed with the active calcium component and then ground. Then, it is subjected to alternating impregnation treatment under normal pressure and negative pressure. After completion, the active calcium loaded carrier slurry is obtained for later use. The active calcium component: one-dimensional chain or porous inorganic carrier = 40~75 parts by weight: 10~35 parts by weight. (3) Add dendritic amine components and imidazole inducing components to the active calcium-supported carrier slurry, and then adjust the system to alkaline and stir the reaction; after completion, dry the obtained slurry and make it into powder to obtain the pre-carbonized directional nucleating agent; the ratio of dendritic amine components: imidazole inducing components: carboxyl confinement agent = 0.1~3 parts by weight: 0.05~2 parts by weight: 0.05~2 parts by weight.

2. The method for preparing the pre-carbonized directional nucleating agent according to claim 1, characterized in that, In step (1), the solid content of the mixture is 30~40 wt.%.

3. The method for preparing the pre-carbonized directional nucleating agent according to claim 1, characterized in that, In step (2), the active calcium component includes one or more of the following: carbide slag powder, calcium oxide, steel slag powder, and recycled concrete powder.

4. The method for preparing the pre-carbonized directional nucleating agent according to claim 1, characterized in that, In steps (1) and (2), the grinding time is 25-35 min; or, in step (2), the alternating impregnation method includes: first stirring under normal pressure for 5-20 min, then standing under negative pressure of -0.02 to -0.08 MPa for 5-30 min, and repeating the above operation 1-3 times.

5. The method for preparing the pre-carbonized directional nucleating agent according to claim 1, characterized in that, In step (3), the dendritic amino component includes one or more of hyperbranched polyethyleneimine, chitosan, polylysine, and aminated lignin; or, in step (3), the imidazole-inducing component includes one or more of histidine and polyvinylimidazole.

6. The method for preparing the pre-carbonized directional nucleating agent according to claim 1, characterized in that, In step (3), the alkalinity is pH=10~12; or, in step (3), the stirring reaction time is 20~90min.

7. The method for preparing the pre-carbonized directional nucleating agent according to any one of claims 1-6, characterized in that, In step (3), the particle size of the pre-carbonized directional nucleating agent is 5~100μm.

8. A method for preparing carbonation-resistant hypersulfate cement, characterized in that, The process includes the following steps: using slag powder, gypsum powder, aluminate cement, the precarbonation directional nucleating agent and water-reducing agent in the preparation method according to any one of claims 1-7 as raw materials, mixing them with mixing water, and then placing them in a CO2 atmosphere for precarbonation and mineralization curing, and after completion, obtaining the carbonation-resistant supersulfate cement. The proportions of each component in the raw materials are as follows: 45-70 parts by weight of slag powder, 20-45 parts by weight of gypsum powder, 5-15 parts by weight of aluminate cement, 2-10 parts by weight of the pre-carbonization directional nucleating agent, and 0.1-1.0 parts by weight of water-reducing agent; the mixing water is added at a water-binder ratio of 0.32-0.45:1, and the "binder" is the sum of the slag powder, gypsum powder, aluminate cement, and pre-carbonization directional nucleating agent.

9. The method for preparing carbonation-resistant hypersulfate cement according to claim 8, characterized in that, The curing begins 0-4 hours after the raw materials are mixed with the mixing water; or, the CO2 volume fraction in the pre-carbonization and mineralization curing is 1-10%, the curing time is 0.5-6 hours, the relative humidity is 55-85%, and the temperature is 20-40℃.

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