Carbon sequestration type concrete internal curing material based on NaX molecular sieve and preparation method thereof

Abstract

The application discloses a kind of carbon sequestration type concrete internal curing material based on NaX molecular sieve and preparation method thereof, belong to building material technical field.It is prepared by the following component raw materials by weight fraction: 15%~18% NaX molecular sieve, 8%~10% carboxymethyl cellulose, 6%~8% bagasse cellulose, 5%~10% polyvinyl alcohol, 24%~30% N-methylol acrylamide, 10%~15% maleic anhydride, 3%~4% xanthan gum, 2%~3% calcium silicate, 8%~10% pentaerythritol allyl ether, 10%~13% propylene glycol polyoxyethylene ether, 0.15%~0.2% glycerol dimethacrylate, 0.2%~0.4% triethylene glycol dimethacrylate, 0.3%~0.7% diallyl dimethyl ammonium chloride, 0.08%~0.5% ammonium sulfite, 1%~3% ammonia.The application develops a kind of concrete internal curing material with CO2 capture and storage function, not only presents good alkali absorption characteristics, improves the mechanical properties of concrete, simultaneously realizes carbon sequestration curing and carbon sequestration service in concrete internal curing process and service process, realizes the new building field carbon sequestration mode of CO2 capture-solidification-storage.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a carbon-fixing concrete internal curing material based on NaX molecular sieve and its preparation method. Background Technology

[0002] High-performance concrete, characterized by a low water-cement ratio and high content of ultrafine mineral powder, is widely used in highways, bridges, dams, industrial applications, and various building structures due to its excellent mechanical properties and durability. However, while achieving high strength, low porosity, and high impermeability, high-performance concrete also significantly increases the risk of cracking. On the one hand, under low water-cement ratio conditions, the internal moisture of the concrete is consumed more quickly; on the other hand, as the density of the concrete structure increases, external curing water has difficulty penetrating its interior, and the water required for later hydration cannot be replenished, exacerbating the self-drying phenomenon within the cement paste, leading to excessive shrinkage and cracking. Furthermore, as the strength of the concrete gradually increases, its tendency for shrinkage cracking becomes more pronounced.

[0003] In recent years, internal curing has become the most effective curing method for high-performance concrete and one of the most effective ways to alleviate self-drying and shrinkage cracking in concrete. This method is simple and easy to operate, eliminating the need for additional equipment and processes such as covering, demolding, and repeated watering, replacing traditional curing techniques like watering, spraying, watering, covering, and mulching, thereby improving construction efficiency. Internal curing technology involves introducing internal curing materials into cement-based materials. As the cement-based materials hydrate, the internal humidity decreases, and the ion concentration or pH increases. The internal curing materials release water, which replenishes the internal humidity of the cement-based materials, reducing shrinkage, optimizing the structure of hydration products, and improving durability.

[0004] Existing internal curing materials face unresolved technical challenges in their application, negatively impacting the rheological and mechanical properties of cement-based composites. Regarding rheological properties, the main issue is that SAP (superacid polymer) incorporated into concrete exhibits low water absorption and poor water retention in the alkaline environment of concrete. This can lead to insufficient and ineffective provision of moisture for concrete setting and hardening, premature moisture release, low internal curing efficiency, and consequently, reduced workability and mechanical properties of the concrete. Furthermore, the majority of existing concrete internal curing material preparation focuses on improving curing efficiency, with very little consideration given to green carbon reduction aspects such as CO2 capture and carbon sequestration. Carbon-fixing internal curing of cement-based materials intervenes during the concrete curing stage, absorbing and solidifying CO2 while simultaneously promoting the setting and hardening process.

[0005] Therefore, improving the water absorption of existing internal curing materials in alkaline environments while maximizing the reduction or offset of CO2 emissions during the production stage, thereby reducing the carbon emissions of cement throughout its entire life cycle and contributing to the development of green and low-carbon applications in building construction, is a new approach to the low-carbon application of concrete in the construction industry. Summary of the Invention

[0006] To overcome the shortcomings of the prior art, the present invention aims to provide a carbon-fixing concrete internal curing material based on NaX molecular sieve and its preparation method, thereby solving the technical problem that existing internal curing materials have low liquid absorption ratios in alkaline environments and poor impact on the mechanical properties of concrete. The present invention develops a concrete internal curing material with CO2 capture and storage functions, which not only exhibits good alkali absorption characteristics and improves the mechanical properties of concrete, but also achieves carbon-fixing curing and carbon-fixing service during the internal curing process and service life of concrete. This realizes a new carbon-fixing model in the construction field of CO2 capture-solidification-storage, providing a basis for carbon reduction technology in the construction field, helping to promote the use of carbon reduction technology, further promoting the development of low-carbon buildings, and providing a research foundation for carbon emission reduction in buildings.

[0007] To achieve the above objectives, the present invention employs the following technical solution:

[0008] This invention provides a carbon-fixing concrete internal curing material based on NaX molecular sieve, which is prepared by weight fraction from the following raw materials: 15%–18% NaX molecular sieve, 8%–10% carboxymethyl cellulose, 6%–8% bagasse cellulose, 5%–10% polyvinyl alcohol, 24%–30% N-hydroxymethyl acrylamide, 10%–15% maleic anhydride, 3%–4% xanthan gum, 2%–3% calcium silicate, 8%–10% pentaerythritol allyl ether, 10%–13% propylene glycol polyoxyethylene ether, 0.15%–0.2% glyceryl dimethacrylate, 0.2%–0.4% triethylene glycol dimethacrylate, 0.3%–0.7% diallyl dimethyl ammonium chloride, 0.08%–0.5% ammonium sulfite, and 1%–3% ammonia.

[0009] In one embodiment, the SiO2 / CaO content ratio in the calcium silicate is 0.99 to 1.15, the sulfate content is <0.05%, and the chloride content is <0.03%.

[0010] The carboxymethyl cellulose is food grade and has a content of ≥95%.

[0011] In one embodiment, the NaX molecular sieve is prepared from the following raw materials: diatomaceous earth, kaolin, NaX molecular sieve seed crystals, sodium hydroxide, silica sol, and deionized water;

[0012] The process for preparing NaX molecular sieves is as follows:

[0013] Diatomaceous earth, kaolin, sodium hydroxide, and silica sol were added sequentially to deionized water and dispersed and dissolved, then ultrasonically dispersed to obtain suspension A.

[0014] NaX molecular sieve seed crystals were added to suspension A, argon gas was introduced, and the mixture was magnetically stirred in a water bath at 25±2℃ to obtain a mixed solution B with a mass concentration of 3%.

[0015] After sealing the mixture B, it was subjected to gelation and crystallization in sequence. The resulting product was cooled to room temperature, washed until neutral, dried, and ground to obtain NaX molecular sieve.

[0016] In one embodiment, the mass ratio of diatomaceous earth, kaolin, sodium hydroxide, silica sol, and deionized water is 3:1:4:16:800.

[0017] In one embodiment, the diatomaceous earth has a particle size of 325 mesh, an Al₂O₃ content of 5.2%, an Fe₂O₃ content of 1.2%, a pH value of 6–8, and a pore volume of 0.45–0.98 cm⁻². 3 / g, with a specific surface area of ​​40-65㎡ / g and an adsorption rate of ≥300%;

[0018] The kaolin has a particle size of 800-1500 mesh, an effective component content of ≥60%, a silica content of ≥50%, and a Mohs hardness of 3-5.

[0019] The silica sol is a transparent or translucent liquid with a SiO2 mass fraction ≥30% and a pH value of 9–11.

[0020] In one embodiment, the mixture B is transferred to a sealed polymerization reactor, the microwave power during gelation is 120W, and the gelation time is 20-60 minutes; the microwave power during crystallization is 700W, and the crystallization time is 60-120 minutes.

[0021] This invention also provides a method for preparing a carbon-fixing type concrete internal curing material based on NaX molecular sieve, comprising the following steps:

[0022] Preparation of NaX molecular sieves;

[0023] Mixture C was prepared by dispersing carboxymethyl cellulose, bagasse cellulose, xanthan gum, and calcium silicate in deionized water;

[0024] Maleic anhydride was prepared into a dilute solution by deionized water, neutralized by ammonia water, and then N-hydroxymethylacrylamide, pentaerythritol allyl ether and propylene alcohol polyoxyethylene ether were added to obtain mixture D.

[0025] Glyceryl dimethacrylate, triethylene glycol dimethacrylate and diallyl dimethyl ammonium chloride were sequentially dispersed in deionized water to prepare mixture E;

[0026] Dehydrated sorbitan tristearate and cyclohexane were stirred and mixed to form the oil phase;

[0027] NaX molecular sieves were added to the oil phase and stirred and mixed under constant temperature water bath conditions. During the stirring and mixing process, the prepared mixture C and polyvinyl alcohol were added and stirring was continued to obtain mixture F.

[0028] Mixture D was added dropwise to mixture F, followed by mixture E. After a set time, ammonium sulfite was added to carry out a graft polymerization reaction to obtain complex G.

[0029] The composite G was soaked and washed to obtain a carbon-fixing concrete internal curing material based on NaX molecular sieve.

[0030] In one embodiment, the mass concentration of the mixture C is 1%; the mass concentration of the dilute maleic anhydride solution is 13%; and the mass concentration of the mixture E is 10%.

[0031] In one embodiment, the dehydrated sorbitan tristearate and cyclohexane are mechanically stirred in a water bath at 40–45°C for 20–50 min to form an oil phase;

[0032] The dehydrated sorbitan tristearate has a cyclohexane mass fraction of 1% to 5%, and the volume ratio of the oil phase to the aqueous phase is 3 to 5:1. The volume of the aqueous phase is the total volume of mixture C (a deionized aqueous solution of carboxymethyl cellulose, bagasse cellulose, xanthan gum, and calcium silicate), mixture D (an aqueous solution of maleic anhydride, ammonia, N-hydroxymethyl acrylamide, pentaerythritol allyl ether, and propylene glycol polyoxyethylene ether), and mixture E (a deionized aqueous solution of dimethacrylate, triethylene glycol dimethacrylate, and diallyl dimethyl ammonium chloride).

[0033] In one embodiment, the set time is 30 minutes, the reaction temperature of the graft polymerization reaction is 40-50°C, the graft polymerization reaction is carried out under argon atmosphere, the reaction process is continuously stirred at a speed greater than 200 r / min, and the time of the graft polymerization reaction is 3-4 hours.

[0034] Compared with the prior art, the present invention has the following beneficial effects:

[0035] This invention provides a NaX molecular sieve-based carbon-fixing concrete internal curing material. Firstly, this material contains NaX molecular sieve components. NaX not only selectively absorbs CO2 but also possesses excellent adsorption capacity. The absorbed and captured CO2, along with the continuous water release during the internal curing process, carbon-fixes the concrete, achieving a novel carbon fixation model in the construction field that captures, solidifies, and seals CO2 during concrete preparation. Intervening during the concrete curing stage, it absorbs and solidifies CO2 while promoting the setting and hardening process of the concrete, maximizing the reduction or offsetting of CO2 emissions during the production stage. It significantly improves the mechanical properties and deformation resistance of concrete and can also be used as an auxiliary material and filler for the rigid skeleton of internal curing materials, significantly improving the hardness and water retention of the internal curing gel. Furthermore, during the later stages of concrete service, the NaX molecular sieve can continue to absorb CO2 and exert its carbon fixation effect. Moreover, diatomaceous earth and kaolin are introduced into the NaX molecular sieve, which significantly reduces the cost of the NaX molecular sieve. At the same time, the invented concrete curing material is green, environmentally friendly and has high strength.

[0036] Secondly, the bagasse cellulose in the material contains a large number of hydroxyl groups in its structure, which can work together with carboxymethyl cellulose to form the organic three-dimensional framework of the NaX molecular sieve-based carbon-fixing concrete internal curing and water-retaining material. This ensures that the organic monomers can fully undergo graft copolymerization. The main monomer component, N-hydroxymethylacrylamide, is a non-ionic monomer with good salt and alkali resistance. Through polymerization, it can continuously fill the NaX molecular sieve framework, which can significantly improve the liquid absorption ratio and water retention performance of the internal curing material. In addition, its superior salt and alkali resistance can, to a certain extent, more effectively adjust the humidity distribution inside the concrete and ensure the internal curing efficiency of the internal curing material in alkaline environments and other saline-alkali media. Therefore, the NaX molecular sieve-based carbon-fixing concrete internal curing and water-retaining material prepared by this invention achieves efficient carbon fixation while having good liquid absorption-storage-water retention performance.

[0037] Finally, the material contains calcium silicate, a major component of concrete. Calcium silicate is easily carbonized and has a great potential to absorb and seal atmospheric CO2, thus endowing the internal curing material with good carbon fixation properties during the concrete's setting and hardening process and even during its service life. Furthermore, calcium silicate provides the initial rigid framework for the NaX molecular sieve-based carbon-fixing concrete internal curing water-retaining material, and its numerous internal pores also provide attachment points for organic monomers during polymerization. The composite between inorganic materials and organic monomers increases the three-dimensional network density of the internal curing material, resulting in excellent water retention performance of the NaX molecular sieve-based carbon-fixing concrete internal curing water-retaining material after curing. The slow release of moisture from the internal curing material replenishes the concrete's moisture consumption, controls and reduces concrete shrinkage, and ensures full hydration of the concrete material. In addition, the presence of a certain amount of calcium silicate within the internal curing material is significant for reducing concrete shrinkage deformation and improving its mechanical properties during the internal curing process.

[0038] Furthermore, NaX molecular sieves, as solid adsorbent materials and aluminosilicate compounds, possess excellent thermal stability, ion exchange capacity, selectivity, and high specific surface area. Due to their unique pore size, molecular sieves can be used to achieve large adsorption capacities for CO2 and moisture. This invention uses diatomaceous earth and kaolin as raw materials for NaX molecular sieves, significantly reducing their cost. Introducing NaX molecular sieves into concrete curing materials can endow them with excellent CO2 capture properties and exert carbon fixation curing and carbon fixation service effects within the concrete, thereby improving the mechanical properties and durability of concrete while promoting the development of low-carbon buildings.

[0039] Furthermore, sugarcane bagasse cellulose contains a large number of hydrophilic groups such as hydroxyl and carboxyl groups in its three-dimensional structure, exhibiting strong water absorption and good salt resistance. Introducing it into concrete curing materials to prepare functional composite superabsorbent polymers not only has economic value, promoting regional economic development, but also has environmental significance, and provides a new approach for the comprehensive utilization of sugarcane bagasse.

[0040] Furthermore, xanthan gum is a white powder, a polysaccharide polymer compound exhibiting a rigid, ordered rod-shaped double helix structure, with a molecular weight generally between 2 × 10⁻⁶. 6 ~5×10 7 It has a slightly foul odor, is readily soluble in water, and its aqueous solution is neutral. Its molecular formula is (C...). 35 H 49 O 29 ) n With a purity of ≥99%, it forms a viscous, transparent or slightly milky white, easily flowing solution when added to water. It has good salt and alkali resistance and can provide an organic cross-linked skeleton for carbon-fixing concrete internal curing materials, ensuring that the internal curing materials have good applicability and stability in alkaline concrete environments. Detailed Implementation

[0041] To enable those skilled in the art to understand the features and effects of the present invention, the terms and expressions used in the specification and claims are explained and defined in general below. Unless otherwise specified, all technical and scientific terms used herein have the ordinary meaning understood by those skilled in the art regarding the present invention, and in case of conflict, the definitions in this specification shall prevail.

[0042] The theories or mechanisms described and disclosed herein, whether right or wrong, should not in any way limit the scope of the invention, that is, the contents of the invention can be implemented without being limited by any particular theory or mechanism.

[0043] In this document, all features defined by numerical ranges or percentage ranges, such as numerical values, quantities, contents, and concentrations, are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible sub-ranges and individual numerical values ​​(including integers and fractions) within those ranges.

[0044] In this article, unless otherwise specified, “contains,” “includes,” “containing,” “has,” or similar terms cover the meanings of “composed of” and “mainly composed of,” for example, “A contains a” covers the meanings of “A contains a and others” and “A contains only a.”

[0045] For the sake of brevity, not all possible combinations of the technical features in each implementation scheme or embodiment are described herein. Therefore, as long as there is no contradiction in the combination of these technical features, the technical features in each implementation scheme or embodiment can be combined arbitrarily, and all possible combinations should be considered within the scope of this specification.

[0046] This invention provides a carbon-fixing concrete internal curing material based on NaX molecular sieve and its preparation method.

[0047] The first aspect provides a carbon-fixing concrete internal curing material based on NaX molecular sieve, which is composed of the following raw materials: NaX molecular sieve, carboxymethyl cellulose, bagasse cellulose, polyvinyl alcohol, N-hydroxymethyl acrylamide, maleic anhydride, xanthan gum, calcium silicate, pentaerythritol allyl ether (PTAE), propylene glycol polyoxyethylene ether (APEG), glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), diallyl dimethyl ammonium chloride (DMDAAC), ammonium sulfite, ammonia, cyclohexane, isopropanol, and sorbitan tristearate (Span-65).

[0048] Specifically, it is prepared from the following components by weight fraction:

[0049] 15%–18% NaX molecular sieve, 8%–10% carboxymethyl cellulose, 6%–8% bagasse cellulose, 5%–10% polyvinyl alcohol, 24%–30% N-hydroxymethyl acrylamide, 10%–15% maleic anhydride, 3%–4% xanthan gum, 2%–3% calcium silicate, 8%–10% pentaerythritol allyl ether (PTAE), 10%–13% propylene glycol polyoxyethylene ether (APEG), 0.15%–0.2% glyceryl dimethacrylate (GDA), 0.2%–0.4% triethylene glycol dimethacrylate (TEGDMA), 0.3%–0.7% diallyl dimethyl ammonium chloride (DMDAAC), 0.08%–0.5% ammonium sulfite, 1%–3% ammonia.

[0050] The calcium silicate is chemically pure, a white powder with a SiO2 / CaO content ratio of 0.99 to 1.15, a sulfate content of <0.05%, and a chloride content of <0.03%.

[0051] Carboxymethyl cellulose is a food-grade, white solid with a content of ≥95%.

[0052] The aforementioned NaX molecular sieve material includes the following raw materials: diatomaceous earth, kaolin, NaX molecular sieve seed crystals, sodium hydroxide, silica sol, and deionized water;

[0053] The preparation process of the NaX molecular sieve material is as follows:

[0054] Diatomaceous earth, kaolin, sodium hydroxide, and silica sol were added sequentially to deionized water and dispersed and dissolved, then ultrasonically dispersed to obtain suspension A.

[0055] NaX molecular sieve seed crystals were added to suspension A, argon gas was introduced, and the mixture was magnetically stirred in a water bath at 25±2℃ to obtain a mixed solution B with a mass concentration of 3%.

[0056] After sealing the mixture B, it was subjected to gelation and crystallization in sequence. The resulting product was cooled to room temperature, washed until neutral, dried, and ground to obtain NaX molecular sieve.

[0057] The specific steps are as follows:

[0058] Step 1: Weigh out diatomaceous earth, kaolin, sodium hydroxide, and silica sol and slowly add them to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse them. Sonicate the mixture for 30 minutes to obtain suspension A.

[0059] Step 2: Slowly add the weighed NaX molecular sieve seed crystals into suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 4 to 8 hours to obtain a mixed solution B with a mass concentration of 3%.

[0060] Step 3: Transfer the mixture B into a sealed polymerization reactor and gel at 120W for 20-60 minutes. Then, increase the microwave power to 700W and crystallize for 60-120 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain the NaX molecular sieve material.

[0061] The diatomaceous earth particles have a particle size of 325 mesh, an Al₂O₃ content of 5.2%, an Fe₂O₃ content of 1.2%, a pH value of 6–8, and a pore volume of 0.45–0.98 cm³. 3 / g, with a specific surface area of ​​40-65㎡ / g and an adsorption rate of ≥300%.

[0062] Kaolin has a particle size of 800-1500 mesh, an effective component content of ≥60%, a silica content of ≥50%, and a Mohs hardness of 3-5.

[0063] Sodium hydroxide is of analytical grade and has a content of ≥96%.

[0064] Silica sol is a transparent or translucent liquid with a SiO2 mass fraction ≥30% and a pH value of 9–11.

[0065] This invention also provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. The method uses the aforementioned formula for preparing the NaX molecular sieve-based carbon-fixing concrete internal curing material and includes the following steps:

[0066] Step 1: Weigh the above raw materials according to their weight;

[0067] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0068] Step 3: Slowly add NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 4 to 8 hours to obtain a mixed solution B with a mass concentration of 3%.

[0069] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use microwave power of 120W to gel for 20-60 minutes. Then, increase the microwave power to 700W and crystallize for 60-120 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0070] Step 5: Slowly and evenly disperse the weighed carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum and calcium silicate into deionized water, and stir magnetically for 30 minutes to prepare a mixed solution C with a mass concentration of 1%.

[0071] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0072] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0073] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a water bath at 40-45°C for 20-50 minutes until they are completely mixed to form the oil phase.

[0074] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 30-45℃. During continuous stirring, slowly add the pre-selected mixture of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate C and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain mixture F.

[0075] Step 10: Slowly add mixture D to mixture F over a period of 1 to 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed > 200 r / min). After reacting for 3 to 4 hours, complex G is obtained.

[0076] Step 11: Take out the composite G, soak and wash it with isopropanol 3 to 5 times, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0077] In step eight, after sorbitan tristearate (Span-65) and cyclohexane are mechanically stirred and mixed completely in a water bath at 40-45°C, an oil phase is formed. The mass fraction of sorbitan tristearate (Span-65) is 1%-5% of cyclohexane. The volume ratio of the oil phase to the water phase is 3-5:1. The volume of the water phase is the total volume of mixture C (a deionized aqueous solution of carboxymethyl cellulose, bagasse cellulose, xanthan gum, and calcium silicate), mixture D (an aqueous solution of maleic anhydride, ammonia, N-hydroxymethyl acrylamide, pentaerythritol allyl ether, and propylene glycol polyoxyethylene ether), and mixture E (a deionized aqueous solution of dimethacrylate, triethylene glycol dimethacrylate, and diallyl dimethyl ammonium chloride).

[0078] This invention first uses diatomaceous earth, kaolin, sodium hydroxide, silica sol, and NaX molecular sieve seed crystals to prepare NaX molecular sieve material. Then, carboxymethyl cellulose, bagasse cellulose, and polyvinyl alcohol are used as grafting skeletons. Organic monomers such as N-hydroxymethyl acrylamide and maleic anhydride undergo continuous grafting polymerization under the action of initiators and crosslinking agents. During this process, NaX molecular sieve material and calcium silicate also continuously participate in the grafting polymerization and filling of the organic network structure of the internal maintenance material. After the reaction is completed, the product is dehydrated, dried, and screened using isopropanol to obtain the long-lasting salt and alkali resistant internal maintenance water-retaining material.

[0079] The salt and alkali resistance of the NaX molecular sieve-based carbon-fixing concrete internal curing and water-retaining material prepared by this invention is improved, and the compressive strength and shrinkage performance of concrete are significantly improved. The 28-day compressive strength of the concrete is more than 110% of the benchmark concrete strength, and the shrinkage rate is less than 40%. In addition, it also exhibits excellent CO2 adsorption effect.

[0080] In summary, this invention provides a carbon-fixing concrete internal curing material based on NaX molecular sieves and its preparation method, designing concrete materials to enhance their carbon fixation potential. Furthermore, it develops specific methods suitable for carbon fixation curing technology to improve carbon fixation efficiency during the curing process and subsequent concrete setting and oxidation. Therefore, this invention develops a concrete internal curing material with CO2 capture-solidification-storage properties, significantly reducing concrete shrinkage and improving mechanical properties. While fully compensating for internal moisture in the concrete to promote hydration and reduce shrinkage deformation, it can also solidify CO2, promoting green and sustainable building development, facilitating the widespread use of carbon reduction technologies, further advancing the development of low-carbon concrete buildings, and providing a research foundation for building carbon emission reduction.

[0081] The present invention will be 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. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0082] The following examples use instruments and equipment conventional in the art. Experimental methods in the following examples, unless otherwise specified, are generally performed under conventional conditions or as recommended by the manufacturer. All raw materials used in the following examples are conventional commercially available products with specifications conventional in the art. In this specification and the following examples, unless otherwise specified, "%" refers to weight percentage, "parts" refers to parts by weight, and "ratio" refers to weight proportion.

[0083] Example 1:

[0084] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 15% NaX molecular sieve, 8% carboxymethyl cellulose, 6% bagasse cellulose, 5% polyvinyl alcohol, 30% N-hydroxymethyl acrylamide, 10% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 10% acrylonitrile polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.27% triethylene glycol dimethacrylate (TEGDMA), 0.5% diallyl dimethyl ammonium chloride (DMDAAC), 0.08% ammonium sulfite, and 2% ammonia.

[0085] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0086] Step 1: Weigh the above raw materials according to their weight;

[0087] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0088] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0089] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0090] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0091] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0092] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0093] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0094] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0095] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0096] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0097] Example 2:

[0098] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 18% NaX molecular sieve, 10% carboxymethyl cellulose, 8% bagasse cellulose, 5% polyvinyl alcohol, 24% N-hydroxymethyl acrylamide, 10% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 10% acrylamide polyoxyethylene ether (APEG), 0.2% glyceryl dimethacrylate (GDA), 0.4% triethylene glycol dimethacrylate (TEGDMA), 0.3% diallyl dimethyl ammonium chloride (DMDAAC), 0.1% ammonium sulfite, and 1% ammonia.

[0099] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0100] Step 1: Weigh the above raw materials according to their weight;

[0101] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0102] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0103] Step 4: Transfer the mixture B into a sealed polymerization reactor and gel at 120W for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the resulting product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain the NaX molecular sieve material.

[0104] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0105] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0106] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0107] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0108] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0109] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0110] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0111] Example 3:

[0112] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 16% NaX molecular sieve, 9% carboxymethyl cellulose, 6% bagasse cellulose, 6% polyvinyl alcohol, 24% N-hydroxymethyl acrylamide, 11% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 9% pentaerythritol allyl ether (PTAE), 11% propylene glycol polyoxyethylene ether (APEG), 0.17% glyceryl dimethacrylate (GDA), 0.23% triethylene glycol dimethacrylate (TEGDMA), 0.4% diallyl dimethyl ammonium chloride (DMDAAC), 0.2% ammonium sulfite, and 1% ammonia.

[0113] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0114] Step 1: Weigh the above raw materials according to their weight;

[0115] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0116] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0117] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0118] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0119] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0120] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0121] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0122] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0123] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0124] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0125] Example 4:

[0126] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 15% NaX molecular sieve, 8% carboxymethyl cellulose, 6% bagasse cellulose, 5% polyvinyl alcohol, 26% N-hydroxymethyl acrylamide, 10% maleic anhydride, 4% xanthan gum, 2% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 12% acrylyl alcohol polyoxyethylene ether (APEG), 0.18% glyceryl dimethacrylate (GDA), 0.3% triethylene glycol dimethacrylate (TEGDMA), 0.32% diallyl dimethyl ammonium chloride (DMDAAC), 0.2% ammonium sulfite, and 3% ammonia.

[0127] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0128] Step 1: Weigh the above raw materials according to their weight;

[0129] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0130] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0131] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0132] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0133] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0134] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0135] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0136] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0137] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0138] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0139] Example 5:

[0140] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 15% NaX molecular sieve, 9% carboxymethyl cellulose, 7% bagasse cellulose, 7% polyvinyl alcohol, 24% N-hydroxymethyl acrylamide, 12% maleic anhydride, 3.3% xanthan gum, 2.5% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 10% acrylamide polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.27% triethylene glycol dimethacrylate (TEGDMA), 0.7% diallyl dimethyl ammonium chloride (DMDAAC), 0.08% ammonium sulfite, and 1% ammonia.

[0141] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0142] Step 1: Weigh the above raw materials according to their weight;

[0143] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0144] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0145] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0146] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0147] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0148] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0149] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0150] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0151] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0152] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0153] Example 6:

[0154] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 16% NaX molecular sieve, 8% carboxymethyl cellulose, 6% bagasse cellulose, 5% polyvinyl alcohol, 27% N-hydroxymethyl acrylamide, 10% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 13% propylene glycol polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.27% triethylene glycol dimethacrylate (TEGDMA), 0.5% diallyl dimethyl ammonium chloride (DMDAAC), 0.08% ammonium sulfite, and 1% ammonia.

[0155] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0156] Step 1: Weigh the above raw materials according to their weight;

[0157] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0158] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0159] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0160] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0161] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0162] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0163] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0164] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0165] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0166] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0167] Example 7:

[0168] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 15% NaX molecular sieve, 8% carboxymethyl cellulose, 6% bagasse cellulose, 10% polyvinyl alcohol, 24% N-hydroxymethyl acrylamide, 10% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 11% propylene glycol polyoxyethylene ether (APEG), 0.2% glyceryl dimethacrylate (GDA), 0.4% triethylene glycol dimethacrylate (TEGDMA), 0.5% diallyl dimethyl ammonium chloride (DMDAAC), 0.5% ammonium sulfite, and 1.4% ammonia.

[0169] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0170] Step 1: Weigh the above raw materials according to their weight;

[0171] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0172] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0173] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0174] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0175] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0176] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0177] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0178] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0179] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0180] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0181] Example 8:

[0182] This example provides a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 15% NaX molecular sieve, 8% carboxymethyl cellulose, 6% bagasse cellulose, 5% polyvinyl alcohol, 24% N-hydroxymethyl acrylamide, 15% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 10% pentaerythritol allyl ether (PTAE), 10% propylene glycol polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.2% triethylene glycol dimethacrylate (TEGDMA), 0.3% diallyl dimethyl ammonium chloride (DMDAAC), 0.08% ammonium sulfite, and 1.27% ammonia.

[0183] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0184] Step 1: Weigh the above raw materials according to their weight;

[0185] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0186] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0187] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0188] Step 5: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a 1% (w / w) mixed solution C.

[0189] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0190] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0191] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0192] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0193] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0194] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0195] Comparative Example 1:

[0196] This comparative example presents a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 16% NaX molecular sieve, 10% polyvinyl alcohol, 30% N-hydroxymethylacrylamide, 15% maleic anhydride, 3% xanthan gum, 2% calcium silicate, 9% pentaerythritol allyl ether (PTAE), 11% propylene glycol polyoxyethylene ether (APEG), 0.17% glyceryl dimethacrylate (GDA), 0.23% triethylene glycol dimethacrylate (TEGDMA), 0.4% diallyl dimethyl ammonium chloride (DMDAAC), 0.2% ammonium sulfite, and 3% ammonia.

[0197] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0198] Step 1: Weigh the above raw materials according to their weight;

[0199] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0200] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0201] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0202] Step 5: Slowly and evenly disperse the weighed xanthan gum and calcium silicate into deionized water, and stir magnetically for 30 minutes to prepare a mixed solution C with a mass concentration of 1%.

[0203] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0204] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0205] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0206] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of xanthan gum and calcium silicate and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0207] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0208] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0209] Comparative Example 2:

[0210] This comparative example presents a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 18% NaX molecular sieve, 10% carboxymethyl cellulose, 8% bagasse cellulose, 10% polyvinyl alcohol, 20% maleic anhydride, 4% xanthan gum, 3% calcium silicate, 10% pentaerythritol allyl ether (PTAE), 13% propylene glycol polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.27% triethylene glycol dimethacrylate (TEGDMA), 0.5% diallyl dimethyl ammonium chloride (DMDAAC), 0.08% ammonium sulfite, and 3% ammonia.

[0211] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0212] Step 1: Weigh the above raw materials according to their weight;

[0213] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0214] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0215] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0216] Step 5: Sequentially and slowly disperse the weighed carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate into deionized water, and magnetically stir for 30 minutes to prepare a mixed solution C with a mass concentration of 1%.

[0217] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed pentaerythritol allyl ether (PTAE) and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0218] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0219] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0220] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0221] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0222] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0223] Comparative Example 3:

[0224] This comparative example presents a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 18% NaX molecular sieve, 8% carboxymethyl cellulose, 6% bagasse cellulose, 5% polyvinyl alcohol, 24% N-hydroxymethyl acrylamide, 15% maleic anhydride, 3% xanthan gum, 8% pentaerythritol allyl ether (PTAE), 10% propylene glycol polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.2% triethylene glycol dimethacrylate (TEGDMA), 0.3% diallyl dimethyl ammonium chloride (DMDAAC), 0.08% ammonium sulfite, and 2.27% ammonia.

[0225] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0226] Step 1: Weigh the above raw materials according to their weight;

[0227] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0228] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0229] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0230] Step 5: Slowly and evenly disperse the weighed carboxymethyl cellulose, bagasse cellulose and xanthan gum into deionized water, and stir magnetically for 30 minutes to prepare a mixed solution C with a mass concentration of 1%.

[0231] Step 6: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture D, and transfer it to a brown bottle for storage in the dark for later use;

[0232] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0233] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0234] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose and xanthan gum and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0235] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0236] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0237] Comparative Example 4:

[0238] This comparative example presents a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 10% carboxymethyl cellulose, 8% bagasse cellulose, 10% polyvinyl alcohol, 30% N-hydroxymethyl acrylamide, 10% maleic anhydride, 4% xanthan gum, 3% calcium silicate, 10% pentaerythritol allyl ether (PTAE), 13% propylene glycol polyoxyethylene ether (APEG), 0.2% glyceryl dimethacrylate (GDA), 0.4% triethylene glycol dimethacrylate (TEGDMA), 0.3% diallyl dimethyl ammonium chloride (DMDAAC), 0.1% ammonium sulfite, and 1% ammonia.

[0239] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0240] Step 1: Weigh out the carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate, and slowly and evenly disperse them in deionized water. Stir magnetically for 30 minutes to prepare a mixed solution A with a mass concentration of 1%.

[0241] Step 2: Prepare a 13% dilute solution of the weighed maleic anhydride with deionized water, start stirring, and heat to 40°C; after complete dissolution, wait for the temperature to drop to room temperature, add the weighed ammonia water dropwise, and after neutralization, add the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE), and propylene glycol polyoxyethylene ether (APEG) to obtain mixture B, and transfer it to a brown bottle for storage in the dark for later use;

[0242] Step 3: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution C.

[0243] Step 4: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0244] Step 5: Purge with nitrogen and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. While stirring continuously, slowly add the pre-selected mixed solution A of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain solution D.

[0245] Step 5: Slowly add mixture B to mixture D over a period of 4 hours. After the addition is complete, add mixture C to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex E is obtained.

[0246] Step 6: Take out the composite E, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0247] Comparative Example 5:

[0248] This comparative example presents a method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieves. By weight, it comprises the following raw materials: 17% NaX molecular sieve, 10% carboxymethyl cellulose, 8% bagasse cellulose, 10% polyvinyl alcohol, 30% N-hydroxymethyl acrylamide, 3.3% xanthan gum, 2.5% calcium silicate, 8% pentaerythritol allyl ether (PTAE), 10% propylene glycol polyoxyethylene ether (APEG), 0.15% glyceryl dimethacrylate (GDA), 0.27% triethylene glycol dimethacrylate (TEGDMA), 0.7% diallyl dimethyl ammonium chloride (DMDAAC), and 0.08% ammonium sulfite.

[0249] The preparation method of the above-mentioned NaX molecular sieve-based carbon-fixing concrete internal curing material includes the following steps:

[0250] Step 1: Weigh the above raw materials according to their weight;

[0251] Step 2: Slowly add the weighed diatomaceous earth, kaolin, sodium hydroxide, and silica sol to deionized water in sequence (mass ratio of diatomaceous earth: kaolin: sodium hydroxide: silica sol: deionized water = 3:1:4:16:800) to dissolve or disperse, and sonicate for 30 minutes to obtain suspension A;

[0252] Step 3: Slowly add the weighed NaX molecular sieve seed crystals to suspension A, purge with argon gas, and magnetically stir at a constant temperature of 25±2℃ in a water bath for 6 hours to obtain a mixed solution B with a mass concentration of 3%.

[0253] Step 4: Transfer the mixture B into a polypolymer reactor and seal it. Use a microwave power of 120W to gel for 50 minutes. Then, increase the microwave power to 700W and crystallize for 100 minutes. Cool the obtained product to room temperature, wash it repeatedly with distilled water until neutral, dry it in a vacuum oven at 60°C for 24 hours, and then grind it to obtain NaX molecular sieve material.

[0254] Step 5: Sequentially and slowly disperse the weighed carboxymethyl cellulose, sugarcane bagasse cellulose, xanthan gum, and calcium silicate into deionized water, and magnetically stir for 30 minutes to prepare a mixed solution C with a mass concentration of 1%.

[0255] Step 6: Prepare mixture D by mixing the weighed N-hydroxymethylacrylamide, pentaerythritol allyl ether (PTAE) and propylene glycol polyoxyethylene ether (APEG) with a small amount of deionized water, and transfer it into a brown bottle for storage away from light for later use.

[0256] Step 7: Disperse the weighed glyceryl dimethacrylate (GDA), triethylene glycol dimethacrylate (TEGDMA), and diallyl dimethyl ammonium chloride (DMDAAC) sequentially in deionized water, and stir magnetically for 30 minutes to prepare a 10% mixed solution E.

[0257] Step 8: Weigh out the sorbitan tristearate (Span-65) and cyclohexane and mechanically stir them in a 45°C water bath for 40 minutes until they are completely mixed to form the oil phase.

[0258] Step 9: Slowly add the pre-obtained NaX molecular sieve to the oil phase, purge with nitrogen, and stir at 300 r / min for 30 min in a constant temperature water bath at 40℃. During continuous stirring, slowly add the pre-selected mixed solution C of carboxymethyl cellulose, bagasse cellulose, xanthan gum and calcium silicate, and polyvinyl alcohol in sequence; continue stirring for 30 min to obtain the mixed solution F.

[0259] Step 10: Slowly add mixture D to mixture F over a period of 4 hours. After the addition is complete, add mixture E to a four-necked flask. After 30 minutes, add weighed ammonium sulfite. The temperature is controlled between 40°C and 50°C throughout the process. Argon gas is introduced and stirring is maintained (speed = 300 r / min). After reacting for 4 hours, complex G is obtained.

[0260] Step 11: Take out the composite G, soak and wash it 5 times with isopropanol, and wait until no more isopropanol evaporates to obtain the NaX molecular sieve-based carbon-fixing concrete internal curing material.

[0261] Performance testing

[0262] In use, the NaX molecular sieve-based carbon-fixing concrete internal curing material is directly ground to 200-250 mesh, and then added to the mixing equipment along with cement and other cementitious materials. The maximum liquid absorption ratio of the curing material in saturated Ca(OH)₂ solution and 0.9% wt CaCl₂ solution is tested, along with the compressive strength ratio of the concrete after incorporation and the 28-day shrinkage ratio ratio (compared to the baseline group), are tested according to the requirements of JC901-2002 "Cement Concrete Curing Agent", JT / T522-2004 "Highway Engineering Concrete Curing Agent", and "Test Procedures for Cement and Cement Concrete in Highway Engineering" (JTG / E30-2005). The dosage is 0.2% of the cementitious material dosage. Furthermore, using CO₂ as the adsorbed gas, 0.2g of the internal curing material is placed in a gas adsorption analyzer to test the CO₂ adsorption isotherm of its particles. The specific operation process is as follows: the sample is degassed under vacuum at 120℃ for 2 hours, and the CO2 adsorption isotherm of the material is measured at a certain temperature. The pressure range of the isotherm is 0.0~1.0 bar.

[0263] The specific performance indicators are as follows:

[0264]

[0265] As can be seen from the above examples, this NaX molecular sieve-based carbon-fixing concrete internal curing material not only significantly improves the mechanical strength of concrete but also exhibits excellent CO2 adsorption performance. In the eight examples, the maximum adsorption ratio of this carbon-fixing concrete internal curing material in saturated Ca(OH)2 solution was greater than 65 g / g, and the maximum adsorption ratio in 0.9% wt CaCl2 solution was greater than 80 g / g. Compared with the comparative example, the carbon-fixing concrete internal curing material in the comparative example showed significantly higher adsorption ratios in saturated Ca(OH)2 solution and 0.9% wt CaCl2 solution. The maximum liquid absorption ratio in CaCl2 solution decreased significantly. Furthermore, in all eight examples, the addition of this carbon-fixing concrete internal curing material significantly improved the 7-day and 28-day compressive strength of the concrete, especially the 28-day compressive strength, which increased by more than 10%, with a shrinkage rate of less than 40%. In addition, the CO2 adsorption capacity of this carbon-fixing concrete internal curing material in all eight examples was greater than 47%. Compared with the comparative example, the CO2 adsorption capacity of the examples was approximately 1 to 6 times higher, indicating a significant carbon fixation effect. This suggests that the absence of materials or changes in the proportions, especially the absence of NaX molecular sieves and calcium silicate, significantly affected the carbon fixation effect of this carbon-fixing concrete internal curing material. The absence of some organic monomers only significantly affected the saturated liquid absorption and shrinkage reduction properties of this carbon-fixing internal curing material. Therefore, this carbon-fixing internal curing material exhibits good liquid absorption characteristics in saline-alkali solutions, and can play a good role in strengthening and capturing-solidifying-sealing CO2. It can also greatly reduce the autogenous shrinkage of concrete and has good applicability. It helps to promote the green and sustainable development of buildings and the application of carbon reduction technologies, provides a research basis for building carbon emission reduction, and has broad application prospects.

[0266] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A carbon-fixing concrete internal curing material based on NaX molecular sieve, characterized in that, It is prepared by weight fraction from the following components: 15%~18% NaX molecular sieve, 8%~10% carboxymethyl cellulose, 6%~8% bagasse cellulose, 5%~10% polyvinyl alcohol, 24%~30% N-hydroxymethyl acrylamide, 10%~15% maleic anhydride, 3%~4% xanthan gum, 2%~3% calcium silicate, 8%~10% pentaerythritol allyl ether, 10%~13% propylene glycol polyoxyethylene ether, 0.15%~0.2% glyceryl dimethacrylate, 0.2%~0.4% triethylene glycol dimethacrylate, 0.3%~0.7% diallyl dimethyl ammonium chloride, 0.08%~0.5% ammonium sulfite, and 1%~3% ammonia water; The NaX molecular sieve is prepared from the following raw materials: diatomaceous earth, kaolin, NaX molecular sieve seed crystals, sodium hydroxide, silica sol, and deionized water; The preparation process of the NaX molecular sieve is as follows: Diatomaceous earth, kaolin, sodium hydroxide, and silica sol were added sequentially to deionized water and dispersed and dissolved, then ultrasonically dispersed to obtain suspension A. NaX molecular sieve seed crystals were added to suspension A, argon gas was introduced, and the mixture was magnetically stirred in a water bath at 25±2℃ to obtain a mixed solution B with a mass concentration of 3%. After sealing the mixture B, it was subjected to gelation and crystallization in sequence. The resulting product was cooled to room temperature, washed until neutral, dried, and ground to obtain NaX molecular sieve.

2. The carbon-fixing concrete internal curing material based on NaX molecular sieve according to claim 1, characterized in that, The SiO2 / CaO content ratio in the calcium silicate is 0.99~1.15, the sulfate content is <0.05%, and the chloride content is <0.03%. The carboxymethyl cellulose is food grade and has a content of ≥95%.

3. The carbon-fixing concrete internal curing material based on NaX molecular sieve according to claim 1, characterized in that, The mass ratio of diatomaceous earth, kaolin, sodium hydroxide, silica sol, and deionized water is 3:1:4:16:

800.

4. The NaX molecular sieve-based carbon-fixing concrete internal curing material according to claim 1, characterized in that, The diatomaceous earth has a particle size of 325 mesh, an Al₂O₃ content of 5.2%, an Fe₂O₃ content of 1.2%, a pH value of 6-8, and a pore volume of 0.45-0.98 cm⁻². 3 / g, specific surface area is 40~65m² 2 / g, adsorption rate ≥300%; The kaolin has a particle size of 800~1500 mesh, an effective component content of ≥60%, a silica content of ≥50%, and a Mohs hardness of 3~5. The silica sol is a transparent or translucent liquid with a SiO2 mass fraction ≥30% and a pH value of 9~11.

5. The carbon-fixing concrete internal curing material based on NaX molecular sieve according to claim 1, characterized in that, The mixture B is transferred to a sealed polymerization reactor. During gelation, the microwave power is 120W and the gelation time is 20-60 minutes. During crystallization, the microwave power is 700W and the crystallization time is 60-120 minutes.

6. A method for preparing a carbon-fixing concrete internal curing material based on NaX molecular sieve according to any one of claims 1 to 5, characterized in that, Includes the following steps: Preparation of NaX molecular sieves; Mixture C was prepared by dispersing carboxymethyl cellulose, bagasse cellulose, xanthan gum, and calcium silicate in deionized water; Maleic anhydride was prepared into a dilute solution by deionized water, neutralized by ammonia water, and then N-hydroxymethylacrylamide, pentaerythritol allyl ether and propylene alcohol polyoxyethylene ether were added to obtain mixture D. Glyceryl dimethacrylate, triethylene glycol dimethacrylate and diallyl dimethyl ammonium chloride were sequentially dispersed in deionized water to prepare mixture E; Dehydrated sorbitan tristearate and cyclohexane were stirred and mixed to form the oil phase; NaX molecular sieves were added to the oil phase and stirred and mixed under constant temperature water bath conditions. During the stirring and mixing process, the prepared mixture C and polyvinyl alcohol were added and stirring was continued to obtain mixture F. Mixture D was added dropwise to mixture F, followed by mixture E. After a set time, ammonium sulfite was added to carry out a graft polymerization reaction to obtain complex G. The composite G was soaked and washed to obtain a carbon-fixing concrete internal curing material based on NaX molecular sieve.

7. The preparation method of the carbon-fixing concrete internal curing material based on NaX molecular sieve according to claim 6, characterized in that, The mass concentration of mixture C is 1%; the mass concentration of the dilute maleic anhydride solution is 13%; and the mass concentration of mixture E is 10%.

8. The method for preparing the NaX molecular sieve-based carbon-fixing concrete internal curing material according to claim 6, characterized in that, The dehydrated sorbitan tristearate and cyclohexane were mechanically stirred in a water bath at 40-45°C for 20-50 minutes to form the oil phase. The dehydrated sorbitan tristearate has a mass fraction of 1% to 5% of cyclohexane, and the volume ratio of the oil phase to the water phase is 3 to 5:

1.

9. The method for preparing the NaX molecular sieve-based carbon-fixing concrete internal curing material according to claim 6, characterized in that, The set time is 30 minutes, the reaction temperature of the graft polymerization reaction is 40~50℃, the graft polymerization reaction is carried out under argon atmosphere, the reaction process is continuously stirred at a speed greater than 200 r / min, and the time of the graft polymerization reaction is 3~4 hours.

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