A low-carbon cementing material based on manganese slag solid waste and a preparation method thereof

Abstract

This invention relates to the field of low-carbon cementitious materials, specifically to a low-carbon cementitious material based on manganese slag solid waste and its preparation method. It solves technical bottlenecks such as low activity of manganese slag, poor efficiency of traditional activators, and insufficient performance of solid waste-based cementitious materials. The method involves drying and dry-mixing composite modified manganese slag and pre-selected slag powder, adding a composite modified alkaline activator and a polycarboxylate superplasticizer, and continuing dry-mixing to obtain a dry-mixed material. Nano-silica is then dispersed in deionized water to obtain a nano-silica dispersion, which is then injected into the dry-mixed material and stirred. After molding and curing, a low-carbon cementitious material is obtained. The composite modified alkaline activator can improve the utilization rate of solid waste, significantly reduce carbon emissions, and improve the compressive strength and durability of the cementitious material, balancing low carbon, high performance, and environmental friendliness. The composite modified manganese slag can improve the compressive strength and durability of the cementitious material and achieve high solid waste utilization and low carbon emissions.

Description

Technical Field

[0001] This invention relates to the field of low-carbon cementitious materials, specifically to a low-carbon cementitious material based on manganese slag solid waste and its preparation method. Background Technology

[0002] Manganese slag is a major solid waste product of the manganese metallurgical industry. Improperly disposed manganese slag occupies land resources, and the soluble heavy metals it contains may have potential impacts on the surrounding soil and groundwater environment if they seep and spread through leachate. At the same time, traditional silicate cement, as the dominant cementing material, requires a large amount of limestone resources for its production process.

[0003] Against this backdrop, the development of new cementitious materials has become an urgent need for the industry. Manganese slag is rich in cementitious active components such as silicon and aluminum, and can theoretically be used as a substitute for cement raw materials. However, unmodified manganese slag has problems such as low activity, serious particle agglomeration, and poor compatibility with cementitious systems, resulting in insufficient strength and poor durability of the products, which limits its large-scale application.

[0004] Therefore, how to activate the activity of manganese slag and optimize the performance of the cementitious system through modification technology has become the core breakthrough for realizing the high-value utilization of manganese slag and the low-carbon transformation of cementitious materials. Summary of the Invention

[0005] In order to overcome the above-mentioned technical problems, the purpose of this invention is to provide a low-carbon cementitious material based on manganese slag solid waste and its preparation method.

[0006] The objective of this invention can be achieved through the following technical solutions:

[0007] In a first aspect, this application provides a low-carbon cementitious material based on manganese slag solid waste, comprising the following components by weight:

[0008] The mixture consists of 50-70 parts of composite modified manganese slag, 20-40 parts of slag powder as required, 8-15 parts of composite modified alkaline activator, 0.3-0.5 parts of polycarboxylate superplasticizer, 0.8-1.2 parts of nano silica, and 40-60 parts of deionized water.

[0009] The slag powder with a preset surface area of ​​≥450m² is specified. 2 / kg, activity index ≥95%; the particle size of the nano-silica is 10-20nm; the polycarboxylate superplasticizer is Jiangsu Subote PCA. ® -I series polycarboxylate high-performance water-reducing agents;

[0010] The composite modified alkaline activator is prepared by the following steps:

[0011] Step a1: Add methacryloyloxyethyltrimethylammonium chloride and deionized water to a beaker, and stir the mixture for 15-20 minutes at a temperature of 25-30℃ and a stirring rate of 300-350 r / min. Then adjust the pH to 7-9 with sodium hydroxide solution and continue stirring for 30-35 minutes to obtain a quaternary ammonium salt solution.

[0012] Step a2: Add the polyamide-amine dendritic polymer to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection. Add N,N-dimethylformamide and stir for 20-30 min at 10-20℃ and 300-400 r / min. Add triethylamine and stir for 10-20 min. Inject lauroyl chloride in one injection and react for 10-10.2 h. Filter with a 0.45 μm organic phase filter membrane and rotary evaporate at 40-45℃. Pour the solution into dichloromethane at twice the product mass and wash with deionized water, retaining the dichloromethane layer. Repeat the washing three times. Dry the oil phase with anhydrous magnesium sulfate for 4-4.2 h. Remove the dichloromethane by rotary evaporation at 30-35℃. Place the product in a vacuum drying oven and dry at 45-50℃ for 24-26 h to obtain the hyperbranched polymer.

[0013] Step a3: Add the hyperbranched polymer and anhydrous ethanol to a beaker and stir for 30-35 minutes at a stirring rate of 300-350 r / min to obtain a hyperbranched polymer solution.

[0014] Step a4: Add water glass to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Purge with nitrogen for protection. Under conditions of 25-30℃ and stirring rate of 300-400 r / min, add quaternary ammonium salt solution dropwise, controlling the dropping rate at 0.3 mL / min. After the addition is complete, stir for 20-25 min. Then add hyperbranched polymer solution dropwise, controlling the dropping rate at 0.5 mL / min. After the addition is complete, continue stirring for 30-35 min. Then adjust the pH value to 10-12 with sodium hydroxide solution, raise the temperature to 30-35℃, continue stirring for 60-65 min, and cool to room temperature to obtain the composite modified alkaline activator.

[0015] In a preferred embodiment of the present invention, the ratio of methacryloyloxyethyltrimethylammonium chloride to deionized water in step a1 is 20-22g:100-110mL.

[0016] In a preferred embodiment of the present invention, the concentration of the sodium hydroxide solution in step a1 is 1 mol / L.

[0017] In a preferred embodiment of the present invention, the ratio of polyamide-amine dendritic polymer, N,N-dimethylformamide, triethylamine and lauroyl chloride in step a2 is 444-454g: 300-400mL: 91-93g: 194-198g.

[0018] In a preferred embodiment of the present invention, the polyamide-amine dendritic polymer in step a2 is from Weihai Chenyuan Molecular New Materials Co., Ltd., and its brand name is CYD-110H.

[0019] In a preferred embodiment of the present invention, the ratio of hyperbranched polymer to anhydrous ethanol in step a3 is 5-7g: 20-28mL.

[0020] In a preferred embodiment of the present invention, the ratio of water glass, quaternary ammonium salt solution and hyperbranched polymer solution in step a4 is 200-220g: 100-110mL: 20-22mL.

[0021] In a preferred embodiment of the present invention, the concentration of the sodium hydroxide solution in step a4 is 1 mol / L.

[0022] In a preferred embodiment of the present invention, the water glass in step a4 has a modulus of 2.4, a concentration of 40%, and a density of 1.38-1.40 g / cm³. 3 .

[0023] The composite modified manganese slag is prepared by the following steps:

[0024] Step b1: Crush the manganese slag to a particle size ≤5mm, dry it in a drying oven at 100-105℃ for 12-13 hours, cool it to room temperature, and then add it to a planetary ball mill. Set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 60-90 minutes to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0025] Step b2: Add silane coupling agent, anhydrous ethanol and deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir the reaction at 25-30℃ and 300-400 r / min for 20-30 min. Then adjust the pH to 4-5 with hydrochloric acid and hydrolyze for 30-35 min to obtain silane hydrolysate.

[0026] Step b3: Add the manganese slag to a high-speed disperser. Under the conditions of 25-30℃ and 1400-1500r / min, add silane hydrolysate dropwise. After the addition is complete, continue stirring for 60-70min. Then place it in a vacuum drying oven and dry it at 75-80℃ for 4-5h. Cool it to room temperature to obtain composite modified manganese slag.

[0027] In a preferred embodiment of the present invention, the ratio of silane coupling agent, anhydrous ethanol and deionized water in step b2 is 8-10g: 40-48mL: 10-12mL.

[0028] In a preferred embodiment of the present invention, the hydrochloric acid in step b2 has a mass fraction of 10%.

[0029] In a preferred embodiment of the present invention, the ratio of manganese slag to silane hydrolysate in step b3 is 1000-1200g: 50-60mL.

[0030] Secondly, this application provides a method for preparing a low-carbon cementitious material based on manganese slag solid waste, comprising the following steps:

[0031] Step 1: Place the composite modified manganese slag and the pre-required slag powder in a vacuum drying oven and dry them at 100-105℃ for 2-3 hours. Then, put them into a planetary mixer and dry mix them at 200-250r / min for 5-8 minutes. Add the composite modified alkaline activator and polycarboxylate superplasticizer, and continue to dry mix them at 200-250r / min for 3-5 minutes to obtain the dry-mixed material.

[0032] Step 2: Add nano-silica to deionized water and place it in an ultrasonic cell disruptor. Disperse the nano-silica for 30-35 minutes at a power of 200W and a frequency of 30kHz to obtain a nano-silica dispersion. Inject the nano-silica dispersion into the dry mixture and stir at a low speed of 200-300r / min for 3-5 minutes, then stir at a high speed of 350-400r / min for 6-10 minutes. After that, pour the mixture into a mold and place it on a vibration table. Vibrate it for 2-3 minutes at an amplitude of 0.5-1mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand for 24 hours at a temperature of 20-22℃. Remove the mold and transfer it to a standard curing chamber for curing. Cure it for 28 days at a temperature of 20-22℃ and a relative humidity of ≥90% to obtain a low-carbon cementitious material.

[0033] The beneficial effects of this invention are:

[0034] This invention discloses a low-carbon cementitious material based on manganese slag solid waste and its preparation method. The method involves drying composite modified manganese slag and pre-defined slag powder, then dry-mixing them in a planetary mixer. A composite modified alkaline activator and a polycarboxylate superplasticizer are added and the mixture is further dry-mixed to obtain a dry-mixed material. Nano-silica is dispersed in deionized water to obtain a nano-silica dispersion, which is then injected into the dry-mixed material. The mixture is first stirred at low speed, then at high speed, followed by molding and curing to obtain the low-carbon cementitious material. The composite modified alkaline activator can significantly reduce the amount of cement clinker used, improve solid waste utilization, significantly reduce carbon emissions, and improve the compressive strength and durability of the cementitious material. It balances low carbon footprint, high performance, and environmental friendliness, providing core support for the large-scale application of solid waste-based cementitious materials. The composite modified manganese slag can improve the compressive strength and durability of the cementitious material, while achieving high solid waste utilization and low carbon emissions.

[0035] In the preparation of low-carbon cementitious materials, a composite modified alkaline activator was first prepared. A highly stable cationic quaternary ammonium salt solution was prepared through physical dissolution and pH adjustment, providing active sites for subsequent cationic modification of water glass. Then, hydrophobic long chains were grafted onto polyamide-amine dendritic polymer molecules via esterification, retaining some hydroxyl groups, to prepare a hyperbranched polymer with both "multiple active sites and steric hindrance effect," providing a structural basis for improving the dispersibility and interfacial compatibility of water glass. The polyamide-amine dendritic polymer used (with 8 hydroxyl groups at the end) was dissolved in N,N-dimethylformamide, and triethylamine was added and stirred. Triethylamine, as an organic acid-binding agent, has an alkaline amino group that can neutralize subsequent reactions. The generated HCl should be avoided to prevent corrosion of equipment or damage to the ester bonds. Lauroyl chloride (containing acyl chloride groups) is then injected in a single step. The acyl chloride groups of the lauroyl chloride undergo esterification with the terminal hydroxyl groups of the polyamide-amine dendritic polymer, forming ester bonds. This achieves grafting of the lauroyl chain (a hydrophobic long chain) onto the polyamide-amine dendritic polymer molecule. The solid hyperbranched polymer is then converted into a solution to prevent localized agglomeration during subsequent mixing with water glass, ensuring uniform modification. Water glass dissociates in water to generate silica anions. The solution is alkaline, and the silica anions are negatively charged, easily agglomerating due to electrostatic attraction. A quaternary ammonium salt solution (containing quaternary ammonium cations) is added dropwise. The quaternary ammonium cations electrostatically adsorb the silica anions from the water glass. The adsorption process (attraction between positive and negative charges) partially neutralizes the surface charge of the silicon-oxygen anions, reducing electrostatic repulsion and agglomeration tendency between particles. Then, an ethanol solution of the hyperbranched polymer is added. The hydrophilic groups (hydroxyl groups, ester bonds) of the hyperbranched polymer interact with the silanol groups on the water glass surface in two ways: first, hydrogen bonding, where -Si-OH forms OH…O hydrogen bonds with -OH / -COO-, enhancing the interfacial bonding between the organic phase (hyperbranched polymer) and the inorganic phase (water glass); second, a weak condensation reaction, where some -Si-OH undergoes dehydration condensation with -OH to form Si-OC covalent bonds, further stabilizing the composite system. The hyperbranched spatial structure of the hyperbranched polymer also creates steric hindrance, hindering the flow of water glass. Glass particles are brought closer together, further inhibiting agglomeration; this addresses the shortcomings of traditional water glass, such as easy agglomeration and poor interfacial compatibility, while retaining its strong alkaline activation ability, ultimately resulting in a composite activator with both high activation efficiency and good dispersibility; the composite modified alkaline activator efficiently activates the active silicon-aluminum components in manganese slag and slag powder, significantly reducing cement clinker usage, improving solid waste utilization, and significantly reducing carbon emissions; organic components (quaternary ammonium salts, hyperbranched polymers) improve the system's dispersibility and interfacial bonding, inhibit particle agglomeration, and enhance the compressive strength and durability of cementitious materials; it optimizes slurry workability to meet construction needs, while stabilizing heavy metal leaching, taking into account low carbon, high performance, and environmental friendliness, providing core support for the large-scale application of solid waste-based cementitious materials.

[0036] In the preparation of low-carbon cementitious materials, a composite modified manganese slag was first prepared. Physical activation was achieved by mechanically altering the physical structure and surface properties of the manganese slag. Then, a silane coupling agent underwent alkoxyl hydrolysis under weakly acidic conditions to generate reactive silanol groups, preparing for subsequent bonding with the manganese slag surface. Following this, the silane hydrolysate underwent a chemical condensation reaction with the manganese slag surface, coating it with an organosilane layer, thus achieving composite modification of "inorganic powder and organic groups." The resulting composite modified manganese slag retains the highly active silicon-aluminum components while also exhibiting improved properties through mechanical modification. The organosilane layer improves compatibility with the cementitious system, inhibits particle agglomeration, and strengthens interfacial bonding, laying the foundation for improving the performance of low-carbon cementitious materials. The composite modified manganese slag, through the synergistic effect of mechanical activation and silane modification, is the core key to enhancing the efficiency of low-carbon cementitious materials. Mechanical activation increases the specific surface area of ​​manganese slag, destroys the inert lattice, and efficiently releases silicon and aluminum activity. Silane modification optimizes surface compatibility through chemical grafting, inhibits particle agglomeration, and strengthens the interfacial bonding with activators and slag. At the same time, it significantly improves the compressive strength and durability of cementitious materials, and achieves high solid waste utilization and low carbon emissions. Detailed Implementation

[0037] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0038] Example 1:

[0039] This embodiment describes a method for preparing a low-carbon cementitious material based on manganese slag solid waste, including the following steps:

[0040] Step s1: Add 20g of methacryloyloxyethyltrimethylammonium chloride and 100mL of deionized water to a beaker, stir the mixture at 25℃ and 300r / min for 15min, then adjust the pH to 7 with 1mol / L sodium hydroxide solution and continue stirring for 30min to obtain a quaternary ammonium salt solution.

[0041] Step s2: Add 444g of polyamide-amine dendritic polymer (the polyamide-amine dendritic polymer is from Weihai Chenyuan Molecular New Materials Co., Ltd., brand name CYD-110H) to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection. Add 300mL of N,N-dimethylformamide. Stir and react for 20min at 10℃ and a stirring rate of 300r / min. Then add 91g of triethylamine and stir and react for another 10min. 194g of lauroyl chloride was injected at once using a syringe and reacted for 10 hours. The mixture was filtered through a 0.45μm organic phase filter membrane and rotary evaporated at 40℃. The product was then poured into dichloromethane at twice its mass, and deionized water was added for washing. The dichloromethane layer was retained and washed repeatedly three times. The oil phase was dried with anhydrous magnesium sulfate for 4 hours. The dichloromethane was removed by rotary evaporation at 30℃. The product was then placed in a vacuum drying oven and dried at 45℃ for 24 hours to obtain the hyperbranched polymer.

[0042] Step s3: Add 5g of hyperbranched polymer and 20mL of anhydrous ethanol to a beaker, and stir the mixture at a stirring rate of 300r / min for 30min to obtain a hyperbranched polymer solution.

[0043] Step s4: Add 200g of water glass (water glass modulus 2.4, concentration 40%, density 1.38g / cm³) 3 The solution was added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Nitrogen gas was introduced for protection. Under the conditions of 25℃ and stirring rate of 300 r / min, 100 mL of quaternary ammonium salt solution was added dropwise at a rate of 0.3 mL / min. After the addition was completed, the mixture was stirred for 20 min. Then, 20 mL of hyperbranched polymer solution was added dropwise at a rate of 0.5 mL / min. After the addition was completed, the mixture was stirred for another 30 min. The pH value was then adjusted to 10 with 1 mol / L sodium hydroxide solution. The temperature was raised to 30℃ and the mixture was stirred for another 60 min. The mixture was then cooled to room temperature to obtain the composite modified alkaline activator.

[0044] Step s5: Crush 1000g of manganese slag to a particle size ≤5mm, dry it in a 100℃ drying oven for 12h, cool it to room temperature, add it to a planetary ball mill, set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 60min to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0045] Step s6: Add 8g of silane coupling agent, 40mL of anhydrous ethanol and 10mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir the reaction at 25℃ and 300r / min for 20min. Then adjust the pH to 4 with 10% hydrochloric acid and hydrolyze for 30min to obtain silane hydrolysate.

[0046] Step s7: Add 1000g of manganese slag to a high-speed disperser. Under the conditions of 25℃ and 1400r / min, add 50mL of silane hydrolysate dropwise. After the addition is complete, continue stirring for 60min. Then place it in a vacuum drying oven and dry it at 75℃ for 4h. Cool it to room temperature to obtain composite modified manganese slag.

[0047] Step s8: Mix 50 parts of composite modified manganese slag and 20 parts of slag powder with a pre-defined surface area ≥ 450 m². 2 (kg, activity index ≥95%) was placed in a vacuum drying oven and dried at 100℃ for 2 hours. Then, it was placed in a planetary mixer and dry-mixed at 200 rpm for 5 minutes. 8 parts of composite modified alkaline activator and 0.3 parts of polycarboxylate superplasticizer (the polycarboxylate superplasticizer was Jiangsu Subote PCA) were added. ® -I series polycarboxylate high-performance water-reducing agent), continue to dry mix at 200 r / min for 3 min to obtain dry mixed material;

[0048] Step s9: Add 0.8 parts of nano silica (nano silica particle size is 10nm) to 40 parts of deionized water, place it in an ultrasonic cell disruptor, and disperse it for 30 min at a power of 200W and a frequency of 30kHz to obtain a nano silica dispersion. Inject the nano silica dispersion into the dry mixture, stir at a low speed of 200r / min for 3 min, and then stir at a high speed of 350r / min for 6 min. Then pour it into a 40mm×40mm×160mm mold, place it on a vibration table, and vibrate for 2 min at an amplitude of 0.5mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand at 20℃ for 24 h. Remove the mold and transfer it to a standard curing chamber for curing. Curing is carried out for 28 days at a temperature of 20℃ and a relative humidity of ≥90% to obtain a low-carbon cementitious material.

[0049] Table 1 Chemical composition of manganese slag

[0050]

[0051] Example 2:

[0052] This embodiment describes a method for preparing a low-carbon cementitious material based on manganese slag solid waste, including the following steps:

[0053] Step s1: Add 21g of methacryloyloxyethyltrimethylammonium chloride and 105mL of deionized water to a beaker, stir the mixture at 27℃ and 330r / min for 17min, then adjust the pH to 8 with 1mol / L sodium hydroxide solution and continue stirring for 33min to obtain a quaternary ammonium salt solution.

[0054] Step s2: Add 449g of polyamide-amine dendritic polymer (the polyamide-amine dendritic polymer is from Weihai Chenyuan Molecular New Materials Co., Ltd., brand name CYD-110H) to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection. Add 350mL of N,N-dimethylformamide and stir for 25min at 15℃ and a stirring rate of 350r / min. Add 92g of triethylamine and stir for another 15min. Then, use a syringe... 196g of lauroyl chloride was injected into the injector and reacted for 10.1h. The product was filtered through a 0.45μm organic phase filter membrane and rotary evaporated at 42℃. The product was then poured into dichloromethane at twice its mass, washed with deionized water, and the dichloromethane layer was retained. The washing was repeated three times. The oil phase was dried with anhydrous magnesium sulfate for 4.1h. The dichloromethane was removed by rotary evaporation at 33℃. The product was then placed in a vacuum drying oven and dried at 47℃ for 25h to obtain the hyperbranched polymer.

[0055] Step s3: Add 6g of hyperbranched polymer and 24mL of anhydrous ethanol to a beaker, and stir the mixture at a stirring rate of 320r / min for 33min to obtain a hyperbranched polymer solution.

[0056] Step s4: Add 210g of water glass (water glass modulus 2.4, concentration 40%, density 1.39g / cm³) 3 The solution was added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Nitrogen gas was introduced for protection. Under the conditions of 27℃ and stirring rate of 350 r / min, 105 mL of quaternary ammonium salt solution was added dropwise, with the dropping rate controlled at 0.3 mL / min. After the addition was completed, the mixture was stirred for 23 min. Then, 21 mL of hyperbranched polymer solution was added dropwise, with the dropping rate controlled at 0.5 mL / min. After the addition was completed, the mixture was stirred for another 33 min. Then, the pH value was adjusted to 11 with 1 mol / L sodium hydroxide solution, the temperature was raised to 33℃, and the mixture was stirred for another 62 min. After cooling to room temperature, the composite modified alkaline activator was obtained.

[0057] Step s5: Crush 1000g of manganese slag to a particle size ≤5mm, place it in a drying oven at 103℃ and dry for 12.5h, cool to room temperature, add it to a planetary ball mill, set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 75min to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0058] Step s6: Add 9g of silane coupling agent, 44mL of anhydrous ethanol and 11mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir the reaction at 27℃ and 350r / min for 25min. Then adjust the pH to 4.5 with 10% hydrochloric acid and hydrolyze for 33min to obtain silane hydrolysate.

[0059] Step s7: Add 1100g of manganese slag to a high-speed disperser. Under the conditions of 27℃ and 1450r / min, add 55mL of silane hydrolysate dropwise. After the addition is complete, continue stirring for 65min. Then place it in a vacuum drying oven and dry it at 77℃ for 4.5h. Cool it to room temperature to obtain composite modified manganese slag.

[0060] Step s8: Mix 60 parts of composite modified manganese slag and 30 parts of slag powder with a pre-defined surface area ≥ 450 m². 2 (kg, activity index ≥95%) was placed in a vacuum drying oven and dried at 103℃ for 2.5h. Then, it was placed in a planetary mixer and dry-mixed at 230r / min for 6.5min. 11.5 parts of composite modified alkaline activator and 0.4 parts of polycarboxylate superplasticizer (Jiangsu Subote PCA) were added. ® -I series polycarboxylate high-performance water-reducing agent), continue to dry mix at 230 r / min for 4 min to obtain dry mixed material;

[0061] Step s9: Add 1 part of nano silica (nano silica particle size is 15nm) to 50 parts of deionized water, place it in an ultrasonic cell disruptor, and disperse it for 33 minutes at a power of 200W and a frequency of 30kHz to obtain a nano silica dispersion. Inject the nano silica dispersion into the dry mixture, stir at a low speed of 250r / min for 4 minutes, and then stir at a high speed of 370r / min for 8 minutes. Then pour it into a 40mm×40mm×160mm mold, place it on a vibration table, and vibrate it for 2.5 minutes at an amplitude of 0.7mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand at 21℃ for 24 hours. Remove the mold and transfer it to a standard curing chamber for curing. Curing it for 28 days at a temperature of 21℃ and a relative humidity of ≥90% yields a low-carbon cementitious material.

[0062] Example 3:

[0063] This embodiment describes a method for preparing a low-carbon cementitious material based on manganese slag solid waste, including the following steps:

[0064] Step s1: Add 22g of methacryloyloxyethyltrimethylammonium chloride and 110mL of deionized water to a beaker. Stir the mixture at 30℃ and 350r / min for 20min. Then adjust the pH to 9 with 1mol / L sodium hydroxide solution and continue stirring for 35min to obtain a quaternary ammonium salt solution.

[0065] Step s2: Add 454g of polyamide-amine dendritic polymer (the polyamide-amine dendritic polymer is from Weihai Chenyuan Molecular New Materials Co., Ltd., brand name CYD-110H) to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection. Add 400mL of N,N-dimethylformamide and stir for 30min at 20℃ and a stirring rate of 400r / min. Add 93g of triethylamine and stir for another 20min. Then, use a syringe... 198g of lauroyl chloride was injected into the injector and reacted for 10.2h. The product was filtered through a 0.45μm organic phase filter membrane and rotary evaporated at 45℃. The product was then poured into dichloromethane at twice its mass, washed with deionized water, and the dichloromethane layer was retained. The washing was repeated three times. The oil phase was dried with anhydrous magnesium sulfate for 4.2h. The dichloromethane was removed by rotary evaporation at 35℃. The product was then placed in a vacuum drying oven and dried at 50℃ for 26h to obtain the hyperbranched polymer.

[0066] Step s3: Add 7g of hyperbranched polymer and 28mL of anhydrous ethanol to a beaker, and stir the mixture at a stirring rate of 350r / min for 35min to obtain a hyperbranched polymer solution.

[0067] Step s4: Add 220g of water glass (water glass modulus 2.4, concentration 40%, density 1.40g / cm³) 3 The solution was added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Nitrogen gas was introduced for protection. Under the conditions of 30℃ and stirring rate of 400 r / min, 110 mL of quaternary ammonium salt solution was added dropwise at a rate of 0.3 mL / min. After the addition was completed, the mixture was stirred for 25 min. Then, 22 mL of hyperbranched polymer solution was added dropwise at a rate of 0.5 mL / min. After the addition was completed, the mixture was stirred for another 35 min. The pH value was then adjusted to 12 with 1 mol / L sodium hydroxide solution. The temperature was raised to 35℃ and the mixture was stirred for another 65 min. The mixture was then cooled to room temperature to obtain the composite modified alkaline activator.

[0068] Step s5: Crush 1000g of manganese slag to a particle size ≤5mm, dry it in a 105℃ drying oven for 13 hours, cool it to room temperature, add it to a planetary ball mill, set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 90 minutes to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0069] Step s6: Add 10g of silane coupling agent, 48mL of anhydrous ethanol and 12mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir the reaction at 30℃ and 400r / min for 30min. Then adjust the pH to 5 with 10% hydrochloric acid and hydrolyze for 35min to obtain silane hydrolysate.

[0070] Step s7: Add 1200g of manganese slag to a high-speed disperser. Under the conditions of 30℃ and 1500r / min, add 60mL of silane hydrolysate dropwise. After the addition is complete, continue stirring for 70min. Then place it in a vacuum drying oven and dry it at 80℃ for 5h. Cool it to room temperature to obtain composite modified manganese slag.

[0071] Step s8: Mix 70 parts of composite modified manganese slag and 40 parts of slag powder with a pre-defined surface area ≥ 450 m². 2 (kg, activity index ≥95%) was placed in a vacuum drying oven and dried at 105℃ for 3 hours. Then, it was placed in a planetary mixer and dry-mixed at 250 rpm for 8 minutes. 15 parts of composite modified alkaline activator and 0.5 parts of polycarboxylate superplasticizer (polycarboxylate superplasticizer is Jiangsu Subote PCA) were added. ® -I series polycarboxylate high-performance water-reducing agent), continue to dry mix at 250 r / min for 5 min to obtain dry mixed material;

[0072] Step s9: Add 1.2 parts of nano-silica (particle size of nano-silica is 20nm) to 60 parts of deionized water, place it in an ultrasonic cell disruptor, and disperse it for 35 minutes at a power of 200W and a frequency of 30kHz to obtain a nano-silica dispersion. Inject the nano-silica dispersion into the dry mixture, stir at a low speed of 300r / min for 5 minutes, and then stir at a high speed of 400r / min for 10 minutes. Then pour it into a 40mm×40mm×160mm mold, place it on a vibration table, and vibrate it for 3 minutes at an amplitude of 1mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand at 22℃ for 24 hours. Remove the mold and transfer it to a standard curing box for curing. Curing it at 22℃ and relative humidity ≥90% for 28 days will yield a low-carbon cementitious material.

[0073] Comparative Example 1:

[0074] This comparative example illustrates a method for preparing a low-carbon cementitious material based on manganese slag solid waste, comprising the following steps:

[0075] Step s1: Crush 1000g of manganese slag to a particle size ≤5mm, dry it in a 100℃ drying oven for 12h, cool it to room temperature, add it to a planetary ball mill, set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 60min to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0076] Step s2: Add 8g of silane coupling agent, 40mL of anhydrous ethanol and 10mL of deionized water to a three-necked flask equipped with a stirrer and thermometer. Stir the reaction at 25℃ and 300r / min for 20min. Then adjust the pH to 4 with 10% hydrochloric acid and hydrolyze for 30min to obtain silane hydrolysate.

[0077] Step s3: Add 1000g of manganese slag to a high-speed disperser. Under the conditions of 25℃ and 1400r / min, add 50mL of silane hydrolysate dropwise. After the addition is complete, continue stirring for 60min. Then place it in a vacuum drying oven and dry it at 75℃ for 4h. Cool it to room temperature to obtain composite modified manganese slag.

[0078] Step s4: Mix 50 parts of composite modified manganese slag and 20 parts of slag powder with a pre-defined surface area ≥ 450 m². 2 (kg, activity index ≥95%) was placed in a vacuum drying oven and dried at 100℃ for 2 hours. Then, it was placed in a planetary mixer and dry-mixed at 200 rpm for 5 minutes. 8 parts water glass and 0.3 parts polycarboxylate superplasticizer (Jiangsu Subote PCA) were added. ® -I series polycarboxylate high-performance water-reducing agent), continue to dry mix at 200 r / min for 3 min to obtain dry mixed material;

[0079] Step s5: Add 0.8 parts of nano silica (nano silica particle size is 10nm) to 40 parts of deionized water, place it in an ultrasonic cell disruptor, and disperse it for 30 min at a power of 200W and a frequency of 30kHz to obtain a nano silica dispersion. Inject the nano silica dispersion into the dry mixture, stir at a low speed of 200r / min for 3 min, and then stir at a high speed of 350r / min for 6 min. Then pour it into a 40mm×40mm×160mm mold, place it on a vibration table, and vibrate for 2 min at an amplitude of 0.5mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand at 20℃ for 24 h. Remove the mold and transfer it to a standard curing chamber for curing. Curing is carried out for 28 days at a temperature of 20℃ and a relative humidity of ≥90% to obtain a low-carbon cementitious material.

[0080] Comparative Example 2:

[0081] This comparative example illustrates a method for preparing a low-carbon cementitious material based on manganese slag solid waste, comprising the following steps:

[0082] Step s1: Add 20g of methacryloyloxyethyltrimethylammonium chloride and 100mL of deionized water to a beaker, stir the mixture at 25℃ and 300r / min for 15min, then adjust the pH to 7 with 1mol / L sodium hydroxide solution and continue stirring for 30min to obtain a quaternary ammonium salt solution.

[0083] Step s2: Add 444g of polyamide-amine dendritic polymer (the polyamide-amine dendritic polymer is from Weihai Chenyuan Molecular New Materials Co., Ltd., brand name CYD-110H) to a three-necked flask equipped with a stirrer, thermometer, and gas delivery tube. Purge with nitrogen for protection. Add 300mL of N,N-dimethylformamide. Stir and react for 20min at 10℃ and a stirring rate of 300r / min. Then add 91g of triethylamine and stir and react for another 10min. 194g of lauroyl chloride was injected at once using a syringe and reacted for 10 hours. The mixture was filtered through a 0.45μm organic phase filter membrane and rotary evaporated at 40℃. The product was then poured into dichloromethane at twice its mass, and deionized water was added for washing. The dichloromethane layer was retained and washed repeatedly three times. The oil phase was dried with anhydrous magnesium sulfate for 4 hours. The dichloromethane was removed by rotary evaporation at 30℃. The product was then placed in a vacuum drying oven and dried at 45℃ for 24 hours to obtain the hyperbranched polymer.

[0084] Step s3: Add 5g of hyperbranched polymer and 20mL of anhydrous ethanol to a beaker, and stir the mixture at a stirring rate of 300r / min for 30min to obtain a hyperbranched polymer solution.

[0085] Step s4: Add 200g of water glass (water glass modulus 2.4, concentration 40%, density 1.38g / cm³) 3 The solution was added to a three-necked flask equipped with a stirrer, thermometer, gas delivery tube, and constant pressure dropping funnel. Nitrogen gas was introduced for protection. Under the conditions of 25℃ and stirring rate of 300 r / min, 100 mL of quaternary ammonium salt solution was added dropwise at a rate of 0.3 mL / min. After the addition was completed, the mixture was stirred for 20 min. Then, 20 mL of hyperbranched polymer solution was added dropwise at a rate of 0.5 mL / min. After the addition was completed, the mixture was stirred for another 30 min. The pH value was then adjusted to 10 with 1 mol / L sodium hydroxide solution. The temperature was raised to 30℃ and the mixture was stirred for another 60 min. The mixture was then cooled to room temperature to obtain the composite modified alkaline activator.

[0086] Step s5: Crush 1000g of manganese slag to a particle size ≤5mm, dry it in a 100℃ drying oven for 12h, cool it to room temperature, add it to a planetary ball mill, set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 60min to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0087] Step s6: Mix 50 parts of manganese slag and 20 parts of pre-selected slag powder (pre-selected slag powder specific surface area ≥ 450 m²). 2 (kg, activity index ≥95%) was placed in a vacuum drying oven and dried at 100℃ for 2 hours. Then, it was placed in a planetary mixer and dry-mixed at 200 rpm for 5 minutes. 8 parts of composite modified alkaline activator and 0.3 parts of polycarboxylate superplasticizer (the polycarboxylate superplasticizer was Jiangsu Subote PCA) were added. ® -I series polycarboxylate high-performance water-reducing agent), continue to dry mix at 200 r / min for 3 min to obtain dry mixed material;

[0088] Step s7: Add 0.8 parts of nano silica (nano silica particle size is 10nm) to 40 parts of deionized water, place it in an ultrasonic cell disruptor, and disperse it for 30 min at a power of 200W and a frequency of 30kHz to obtain a nano silica dispersion. Inject the nano silica dispersion into the dry mixture, stir at a low speed of 200r / min for 3 min, and then stir at a high speed of 350r / min for 6 min. Then pour it into a 40mm×40mm×160mm mold, place it on a vibration table, and vibrate for 2 min at an amplitude of 0.5mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand at 20℃ for 24 h. Remove the mold and transfer it to a standard curing chamber for curing. Curing is carried out for 28 days at a temperature of 20℃ and a relative humidity of ≥90% to obtain a low-carbon cementitious material.

[0089] Comparative Example 3:

[0090] This comparative example illustrates a method for preparing a low-carbon cementitious material based on manganese slag solid waste, comprising the following steps:

[0091] Step s1: Crush 1000g of manganese slag to a particle size ≤5mm, dry it in a 100℃ drying oven for 12h, cool it to room temperature, add it to a planetary ball mill, set the ball-to-material ratio to 4:1, the rotation speed to 350r / min, and grind for 60min to achieve a specific surface area ≥400m². 2 / kg, then passed through a 320-mesh standard sieve to obtain manganese slag;

[0092] Step s2: Mix 50 parts of manganese slag and 20 parts of pre-selected slag powder (pre-selected slag powder specific surface area ≥ 450 m²). 2 (kg, activity index ≥95%) was placed in a vacuum drying oven and dried at 100℃ for 2 hours. Then, it was placed in a planetary mixer and dry-mixed at 200 rpm for 5 minutes. 8 parts water glass and 0.3 parts polycarboxylate superplasticizer (Jiangsu Subote PCA) were added. ® -I series polycarboxylate high-performance water-reducing agent), continue to dry mix at 200 r / min for 3 min to obtain dry mixed material;

[0093] Step s3: Add 0.8 parts of nano silica (nano silica particle size is 10nm) to 40 parts of deionized water, place it in an ultrasonic cell disruptor, and disperse it for 30 min at a power of 200W and a frequency of 30kHz to obtain a nano silica dispersion. Inject the nano silica dispersion into the dry mixture, stir at a low speed of 200r / min for 3 min, and then stir at a high speed of 350r / min for 6 min. Then pour it into a 40mm×40mm×160mm mold, place it on a vibration table, and vibrate for 2 min at an amplitude of 0.5mm and a frequency of 50Hz. Smooth the surface of the mold with a scraper, cover it with plastic wrap, and let it stand at 20℃ for 24 h. Remove the mold and transfer it to a standard curing chamber for curing. Curing is carried out for 28 days at a temperature of 20℃ and a relative humidity of ≥90% to obtain a low-carbon cementitious material.

[0094] Performance testing:

[0095] The compressive and flexural strengths of Examples 1-3 and Comparative Examples 1-3 were tested according to GB / T 17671-2021 "Test Method for Strength of Cement Mortar (ISO Method)"; carbon emissions were tested according to GB / T 32151.8-2023 "Carbon Emission Accounting and Reporting Requirements Part 8: Cement Production Enterprises"; and solid waste utilization rate was tested according to GB / T 44028-2024 "Calculation Method for Utilization Rate of Iron Ore Waste Rock" and GB / T44033-2024 "Calculation Method for Utilization Rate of Iron Ore Tailings". The formula is: Solid waste utilization rate (%) = [Solid waste usage amount / (Solid waste usage amount + Non-solid waste raw material amount)] × 100%.

[0096] The test results are shown in the table below:

[0097] Table 2 Performance Test Results

[0098]

[0099] Referring to Table 2, a comparison between Examples 1-3 and Comparative Examples 1-3 shows that the mechanical properties of low-carbon cementitious materials are significantly improved, and their environmental protection and low-carbon benefits are outstanding.

[0100] Based on the comparison between Example 1 and Comparative Example 1, it can be seen that Example 1 uses a composite modified alkaline activator, while Comparative Example 1 uses only unmodified water glass. In the composite modified alkaline activator, the quaternary ammonium salt cation can enhance the charge binding with the surface of manganese slag / slag, improving the interfacial adhesion. The branched structure of the hyperbranched polymer can provide steric hindrance and improve the system dispersibility. The synergistic effect of the three can more efficiently activate the potential hydration activity of manganese slag and slag, promote the generation of more hydration products such as CSH gel, and optimize the microstructure of hydration products. In contrast, unmodified water glass relies solely on alkaline activation, resulting in low activation efficiency and an inability to improve system dispersibility and interfacial bonding. The number of hydration products is small and the structure is loose. Example 1 has significantly higher compressive strength and flexural strength, lower carbon emissions, and higher solid waste utilization rate. Therefore, the performance of Example 1 is superior to that of Comparative Example 1.

[0101] Based on the comparison between Example 1 and Comparative Example 2, it can be seen that Example 1 uses composite modified manganese slag, while Comparative Example 2 uses unmodified manganese slag. After hydrolysis, the silane coupling agent is grafted onto the surface of the manganese slag, which can improve the hydrophilicity and hydrophobicity of the manganese slag surface, enhance its interfacial compatibility with the activator and slag in the cementation system, and reduce defects such as interfacial porosity. At the same time, the modified manganese slag has more active sites on its surface, making it easier to be activated by the activator and promote the hydration reaction. In contrast, the unmodified manganese slag has strong hydrophilicity, poor interfacial bonding, and few active sites, resulting in low hydration activation efficiency and many microstructural defects in the cementation system. Example 1 has better compressive strength and flexural strength, lower carbon emissions, and higher solid waste utilization rate. Therefore, the performance of Example 1 is better than that of Comparative Example 2.

[0102] Based on the comparison between Example 1 and Comparative Example 3, it can be seen that Example 1 uses both a composite modified alkaline activator and a composite modified manganese slag; Comparative Example 3 uses neither a composite modified alkaline activator nor a composite modified manganese slag. The highly efficient activation effect of the composite modified alkaline activator, together with the interface optimization and activity enhancement effect of the composite modified manganese slag, forms a synergistic effect. The former fully activates the hydration potential of manganese slag / slag, while the latter ensures the interfacial bonding and structural compactness of the hydration products after activation. Together, they promote the formation of a large number of hydration products with excellent structure in the cementitious system. However, Comparative Example 3 lacks these two modification measures. It has neither a highly efficient activator to drive hydration nor highly active and highly compatible manganese slag to participate in the reaction. The degree of hydration is extremely low, and the microstructure is loose with many defects. The compressive strength and flexural strength of Example 1 are significantly superior, carbon emissions are significantly reduced, and the solid waste utilization rate is significantly higher. Therefore, the performance of Example 1 is far better than that of Comparative Example 3.

[0103] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0104] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in this application, they should all fall within the protection scope of the present invention.

Claims

1. A low-carbon cementitious material based on manganese slag solid waste, characterized in that, Raw materials comprising the following components by weight: The mixture consists of 50-70 parts of composite modified manganese slag, 20-40 parts of slag powder as required, 8-15 parts of composite modified alkaline activator, 0.3-0.5 parts of polycarboxylate superplasticizer, 0.8-1.2 parts of nano silica, and 40-60 parts of deionized water. Among them, the pre-set requirement is that the specific surface area of ​​the slag powder is ≥450m². 2 / kg, activity index ≥95%; The composite modified alkaline activator is prepared by the following steps: Step a1: Mix methacryloyloxyethyltrimethylammonium chloride and deionized water and stir, then adjust the pH and continue stirring to obtain a quaternary ammonium salt solution; Step a2: Mix polyamide-amine dendritic polymer and N,N-dimethylformamide and stir to react. Then add triethylamine and stir to react. Inject lauroyl chloride to react. Filter, rotary evaporate, then pour into dichloromethane, wash with water, dry, rotary evaporate, and dry to obtain hyperbranched polymer. Step a3: Mix the hyperbranched polymer and anhydrous ethanol and stir to react, to obtain a hyperbranched polymer solution; Step a4: Add quaternary ammonium salt solution dropwise to water glass and stir. Then add hyperbranched polymer solution dropwise and continue stirring. Adjust the pH, raise the temperature, continue stirring, and cool to obtain the composite modified alkaline activator. The composite modified manganese slag is prepared by the following steps: Step b1: Crush, dry, cool, grind, and then pass through a standard sieve to obtain manganese slag; Step b2: Mix the silane coupling agent, anhydrous ethanol and deionized water and stir to react. Then adjust the pH and hydrolyze to obtain silane hydrolysate. Step b3: Disperse the manganese slag at high speed, add silane hydrolysate dropwise, continue stirring, then dry and cool to obtain composite modified manganese slag.

2. The low-carbon cementitious material based on manganese slag solid waste according to claim 1, characterized in that, In step a1, the ratio of methacryloyloxyethyltrimethylammonium chloride to deionized water is 20-22g:100-110mL.

3. The low-carbon cementitious material based on manganese slag solid waste according to claim 1, characterized in that, In step a2, the ratio of polyamide-amine dendritic polymer, N,N-dimethylformamide, triethylamine, and lauroyl chloride is 444-454g: 300-400mL: 91-93g: 194-198g.

4. The low-carbon cementitious material based on manganese slag solid waste according to claim 1, characterized in that, In step a3, the ratio of hyperbranched polymer to anhydrous ethanol is 5-7 g: 20-28 mL.

5. A low-carbon cementitious material based on manganese slag solid waste according to claim 1, characterized in that, In step a4, the ratio of water glass, quaternary ammonium salt solution, and hyperbranched polymer solution is 200-220 g : 100-110 mL : 20-22 mL; the water glass has a modulus of 2.4, a concentration of 40%, and a density of 1.38-1.40 g / cm³. 3 .

6. The low-carbon cementitious material based on manganese slag solid waste according to claim 1, characterized in that, In step b2, the ratio of silane coupling agent, anhydrous ethanol, and deionized water is 8-10 g: 40-48 mL: 10-12 mL.

7. A low-carbon cementitious material based on manganese slag solid waste according to claim 1, characterized in that, In step b3, the ratio of manganese slag to silane hydrolysate is 1000-1200g: 50-60mL.

8. A method for preparing a low-carbon cementitious material based on manganese slag solid waste, characterized in that, The preparation of a low-carbon cementitious material based on manganese slag solid waste as described in any one of claims 1-7 includes the following steps: Step 1: Dry the composite modified manganese slag and the slag powder with the preset requirements, then put them into a planetary mixer for dry mixing, add the composite modified alkaline activator and polycarboxylate superplasticizer, and continue to dry mix to obtain the dry mixed material. Step 2: Disperse nano-silica in deionized water to obtain nano-silica dispersion. Inject the nano-silica dispersion into the dry mixture, stir at low speed first, then stir at high speed, then pour into a mold, let it stand, remove the mold, and cure to obtain low-carbon cementitious material.

9. The method for preparing a low-carbon cementitious material based on manganese slag solid waste according to claim 8, characterized in that, The particle size of nano-silica is 10-20 nm.

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