Modified steel slag mixture and preparation method and application thereof

Abstract

This invention relates to the field of concrete technology, specifically disclosing a modified steel slag mixture, its preparation method, and its application. The modified steel slag mixture comprises: modified steel slag, silicate cement, fly ash, silica fume, activated coal gangue, and emulsified asphalt. The raw materials for preparing the modified steel slag include: steel slag, phosphate-modified graphene oxide, polycarboxylate superplasticizer, water glass, and sodium sulfate. The raw materials for preparing the phosphate-modified graphene oxide include organophosphates and graphene oxide. This invention avoids the agglomeration of nanomaterials in the cement matrix by anchoring P-GO to the surface of the steel slag. The anchored P-GO in situ captures Fe dissolved from C2F. 3+ This drives the continuous dissolution of C2F; water glass and sodium sulfate rapidly consume the dissolved Fe. 3+ and Ca 2+ This process generates C-(F)-S-H gel and ettringite, forming a cycle that simultaneously solves the problems of insufficient early strength and poor volume stability of steel slag.

Description

Technical Field

[0001] This invention relates to the field of concrete technology, and in particular to a modified steel slag mixture, its preparation method, and its application. Background Technology

[0002] Steel slag is an industrial byproduct of steelmaking. Its chemical and mineral composition is similar to that of silicate cement, mainly containing hydraulic minerals such as C2S and C2F, theoretically possessing the potential to serve as a cementitious material. Using steel slag in cement-based materials not only achieves the resource utilization of solid waste but also reduces carbon emissions from cement production, aligning with the demands of green and low-carbon development. However, steel slag faces two major technical bottlenecks in practical applications: First, its dense mineral structure leads to extremely slow hydration under conventional curing conditions, resulting in insufficient early strength development and difficulty in meeting the early mechanical performance requirements of engineering projects. Second, steel slag contains free calcium oxide and free magnesium oxide, which expand in volume during the later stages of hydration, easily causing material cracking and affecting volume stability. These two issues jointly restrict the high-volume application of steel slag in cement-based materials. To address these problems, existing technologies often employ physical grinding, alkali activation, or sulfate activation to enhance the activity of steel slag; however, the effectiveness of a single activation method is limited, and it is difficult to simultaneously achieve both early strength and later stability. Summary of the Invention

[0003] The main objective of this invention is to provide a modified steel slag mixture, its preparation method, and its application. This invention aims to solve the technical problem in the prior art where steel slag, due to its dense mineral structure, undergoes slow hydration under traditional curing conditions, resulting in severely insufficient early strength. By promoting the deep hydration of C2S and C2F, dense C-(F)-SH gel and ettringite are generated, thereby improving the early strength and long-term volume stability of steel slag-based materials.

[0004] To achieve the above objectives, the present invention provides a modified steel slag mixture, which comprises: modified steel slag, silicate cement, fly ash, silica fume, activated coal gangue, and emulsified asphalt;

[0005] The raw materials for preparing the modified steel slag include: steel slag, phosphate-modified graphene oxide, polycarboxylate superplasticizer, water glass, and sodium sulfate;

[0006] The raw materials for preparing the phosphate-modified graphene oxide include organic phosphate esters and graphene oxide.

[0007] According to the first aspect of the present invention, at least the following beneficial effects are achieved:

[0008] (1) This invention solves the problem of insufficient early strength in steel slag mixtures. It anchors phosphate-modified graphene oxide (P-GO) onto the surface of the C2F phase in steel slag, actively capturing and reducing Fe near the interface. 3+ The concentration forces the C2F dissolution equilibrium to shift continuously to the right, thereby activating the inert iron phase. Water glass and sodium sulfate rapidly consume the dissolved Fe within the interfacial microregions. 3+ and Ca 2 + This generates C-(F)-SH gel and ettringite, forming a cycle.

[0009] (2) The problem of poor volume stability of steel slag was solved. The high-density C-(F)-SH transition layer induced by P-GO creates a transition zone between steel slag and cement stone, effectively buffering the internal stress generated by delayed expansion and ensuring the long-term stability of the structure.

[0010] According to some embodiments of the present invention, the raw materials for preparing the modified steel slag mixture, by weight, include: 330-370 parts by weight of silicate cement, 420-460 parts by weight of modified steel slag, 85-95 parts by weight of fly ash, 35-45 parts by weight of silica fume, 65-75 parts by weight of activated coal gangue, and 100-130 parts by weight of emulsified asphalt.

[0011] According to some embodiments of the present invention, the raw materials for preparing the modified steel slag, by weight, include: 100-110 parts of steel slag, 0.5-2.0 parts of phosphate-modified graphene oxide, 5-10 parts of polycarboxylate superplasticizer, 0.5-2.0 parts of water glass, and 0.3-1.2 parts of sodium sulfate.

[0012] According to some embodiments of the present invention, the organophosphate includes at least one of dibutyl phosphate and dioctyl phosphate.

[0013] According to a second aspect of the present invention, a method for preparing the modified steel slag mixture is provided, comprising: mixing silicate cement, modified steel slag, activated coal gangue, fly ash, and silica fume, then adding emulsified asphalt and water, and reacting the mixture to obtain the modified steel slag mixture.

[0014] According to some embodiments of the present invention, the method for preparing the modified steel slag includes:

[0015] S1. Mix the steel slag with the polycarboxylate superplasticizer to form a wet material;

[0016] S2. The phosphate-modified graphene oxide is dispersed and then sprayed onto the wet material to obtain mixture A;

[0017] S3. Mix the mixture A, the solution of the water glass, and the sodium sulfate to obtain mixture B;

[0018] S4. The mixture B is heated and reacted, then dried to obtain the modified steel slag.

[0019] According to some embodiments of the present invention, in step S4, the temperature of the heating reaction is 70~90°C, and the heating reaction time is 40~50 min.

[0020] The preparation method provided by this invention is simple and convenient to operate. Through P-GO anchoring and synergistic activation by water glass and sodium sulfate, the inert C2F phase in steel slag is activated and the interface is strengthened. The modified steel slag obtained has high early strength and good volume stability.

[0021] According to some embodiments of the present invention, in step S1, steel slag and polycarboxylate superplasticizer aqueous solution are mixed at a mass-volume ratio of 1g: 1~2mL and stirred evenly to form a wet material; the mass fraction of the polycarboxylate superplasticizer aqueous solution is 3%~7%.

[0022] According to some embodiments of the present invention, in step S2.1, the organophosphate modified graphene oxide is weighed at a ratio of P-GO mass to steel slag mass of 0.5~1.5:100, dispersed in deionized water, and prepared into a suspension with a solid content of 0.3~0.8wt%, and ultrasonically treated for 10~20min.

[0023] According to some embodiments of the present invention, in step S2.2, under the condition of continuous stirring of the wet material obtained in S1, the P-GO suspension is sprayed at a uniform speed according to the ratio of steel slag mass: P-GO suspension volume = 1g : 0.8~1.5mL, so that it is uniformly coated on the surface of the steel slag to obtain mixture A.

[0024] According to some embodiments of the present invention, in step S2.3, water glass with a modulus of 1.0 to 1.5 is selected, and the water glass stock solution is diluted with deionized water to a solution with a Na2O equivalent concentration of 5 to 8 wt%.

[0025] According to some embodiments of the present invention, in step S3, water glass solution is slowly added dropwise to mixture A while continuously stirring, and sodium sulfate is added at the same time; the amount of water glass added is 0.5~2.0 wt% of the mass of steel slag (calculated as Na2O), and the amount of sodium sulfate added is 0.3~1.2 wt% of the mass of steel slag; mixture B is obtained by stirring while adding water glass.

[0026] According to some embodiments of the present invention, in step S4, the temperature of the heating reaction is 70~90°C, and the heating reaction time is 40~50 min.

[0027] Under the above conditions, the chemical anchoring reaction between P-GO and the steel slag surface can be fully carried out, and the interfacial bonding strength is further improved. At the same time, the activating effect of water glass and sodium sulfate is effectively promoted, the formation rate of C-(F)-SH gel and ettringite is accelerated, and the early hydration activity of steel slag is fully activated.

[0028] According to some embodiments of the present invention, the method for preparing the organophosphate modified graphene oxide includes:

[0029] A1. After dispersing the graphene oxide, add the organic phosphate ester, mix and sonicate, then add xylene to obtain the reaction system;

[0030] A2. The reaction system is heated to react. During the reaction, the generated water is removed by a water separator, and a mixed solvent composed of xylene and N,N-dimethylformamide is added to maintain the stability of the reaction system.

[0031] A3. After the reaction is complete, the product is purified to obtain organophosphate-modified graphene oxide.

[0032] According to some embodiments of the present invention, in step A2, the temperature of the heating reaction is 120~150°C.

[0033] According to some embodiments of the present invention, the method for preparing the organophosphate modified graphene oxide includes:

[0034] A1. After dispersing the graphene oxide, add the organic phosphate ester, mix and sonicate, then add xylene to obtain the reaction system;

[0035] A2. The reaction system is heated to react. During the reaction, the generated water is removed by a water separator, and a mixed solvent composed of xylene and N,N-dimethylformamide is added to maintain the stability of the reaction system.

[0036] A3. After the reaction is complete, the product is purified to obtain organophosphate-modified graphene oxide.

[0037] According to some embodiments of the present invention, in step A2, the temperature of the heating reaction is 120~150°C.

[0038] According to some embodiments of the present invention, the raw materials for preparing the modified steel slag mixture, by weight, include: 330-370 parts by weight of silicate cement, 420-460 parts by weight of modified steel slag, 85-95 parts by weight of fly ash, 35-45 parts by weight of silica fume, 65-75 parts by weight of activated coal gangue, and 100-130 parts by weight of emulsified asphalt.

[0039] According to some embodiments of the present invention, the preparation method of the modified steel slag mixture includes mixing and stirring silicate cement, modified steel slag, activated coal gangue, fly ash and silica fume to obtain dry powder; then adding the emulsified asphalt and water to the dry powder at a water-cement ratio of 0.28 to 0.33, and stirring to obtain the modified steel slag mixture.

[0040] According to a third aspect of the invention, the application of modified steel slag mixtures in concrete is proposed. Detailed Implementation

[0041] The technical solutions of the embodiments 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 a part of the embodiments of the present invention, and not all of the 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.

[0042] Unless otherwise defined, all technical and scientific terms used in this invention have the same meaning as those skilled in the art. The reagents or raw materials used in this invention are readily available through conventional means, and unless otherwise specified, they are used in accordance with conventional methods or product instructions. Furthermore, any methods and materials similar to or equivalent to those described herein can be applied to the methods of this invention. The technical solution of this invention will now be further described in conjunction with specific embodiments.

[0043] The steel slag used, by mass percentage, contains 36% CaO (of which 5% is free calcium oxide), 34% iron oxide, 8% SiO2, 3% Al2O3, with the remainder being unavoidable impurities.

[0044] To further illustrate the present invention, the following examples are provided:

[0045] Example 1

[0046] A modified steel slag mixture, its preparation method, and its application are as follows:

[0047] Preparation of modified steel slag:

[0048] S1. 100 parts of steel slag fine aggregate with a particle size distribution between 0.2 and 0.5 mm are mixed with 120 parts by weight of polycarboxylate superplasticizer aqueous solution to form a wet material; the polycarboxylate superplasticizer aqueous solution has a mass fraction of 5% and is prepared by polycarboxylate superplasticizer (Guangdong Wengjiang Chemical Reagent Co., Ltd., item number PA96208) and water.

[0049] S2.1 Disperse P-GO powder in deionized water to prepare a suspension with a solid content of about 0.5 wt%, and sonicate for 15 min to ensure full dispersion and stability;

[0050] S2.2 Under the condition of continuous stirring of the wet material obtained in S1, the P-GO suspension is sprayed at a uniform speed according to the ratio of steel slag mass: P-GO suspension volume = 1g: 1mL, so that it is evenly coated on the surface of the steel slag to obtain mixture A.

[0051] S2.3 Select water glass with a modulus of 1.5 and dilute the water glass stock solution with deionized water to a solution with a Na2O equivalent concentration of 5wt%.

[0052] S3. Subsequently, while continuously stirring, water glass solution is slowly added dropwise, with the amount of water glass being 1.0 wt% of the steel slag (based on Na2O). Sodium sulfate (0.6 wt% of the steel slag) is added simultaneously while stirring to obtain mixture B.

[0053] S4. The mixture obtained above is heated to 80°C and kept at that temperature for 45 minutes in a closed reactor. After that, the product is placed in an oven and dried at 60°C for 2 hours to obtain modified steel slag.

[0054] S5. Mix coal gangue particles and sodium hydroxide solid powder at a mass ratio of 1:0.15 and stir evenly. Then heat to 580℃ in a muffle furnace and hold for 30 minutes. After completion, cool the product to room temperature and then perform mechanical grinding and sieving to obtain activated coal gangue with a particle size distribution between 0.1 and 0.15 mm.

[0055] S6. Take the following raw materials: 335 parts by weight of 42.5 ordinary Portland cement, 425 parts by weight of modified steel slag in this embodiment, 70 parts by weight of activated coal gangue in this embodiment, 87 parts by weight of Grade I fly ash, 40 parts by weight of silica fume, and 120 parts by weight of emulsified asphalt (Anhui Boyou New Material Co., Ltd.). First, mix the cement, modified steel slag, activated coal gangue, fly ash and silica fume and stir evenly. Then, add the emulsified asphalt and water to the obtained dry powder at a water-cement ratio of 0.3 and stir evenly to obtain the modified steel slag mixture.

[0056] The preparation method of P-GO is as follows:

[0057] A1. Weigh N,N-dimethylformamide (DMF), dibutyl phosphate (DBP), and graphene oxide (GO High-Engineering Technology Co., Ltd.) in a mass ratio of 22:6.5:1, place them in a three-necked flask and mix them. After ultrasonically dispersing the system for 20 hours, add xylene solvent equivalent to 15% of the mass of GO.

[0058] A2. First, raise the temperature to 120℃ and continue the reaction for 4 hours, then raise the temperature to 150℃ and continue the reaction. During the reaction, when the liquid volume in the water separator is full, drain the liquid and add a mixed solvent of xylene and DMF in a volume ratio of 1.5:1 to the system. Repeat this water and solvent replenishment operation, with a total reaction time of 6 hours.

[0059] A3. After the reaction was complete and cooled to room temperature, the resulting suspension was transferred to a centrifuge tube, and twice the volume of xylene was added. The mixture was centrifuged at 8000 rpm. The supernatant was discarded, and a mixed solvent of xylene and DMF at a volume ratio of 1.5:1 was added. After thorough stirring, the mixture was centrifuged again. This washing-centrifugation step was repeated four times. The final product was dried at room temperature to obtain organophosphate-functionalized graphene oxide.

[0060] Example 2

[0061] A modified steel slag, its preparation method, and its application, specifically:

[0062] S1. Steel slag fine aggregate with a particle size distribution between 0.2 and 0.5 mm is mixed with an aqueous solution (mass fraction 5%) of polycarboxylate superplasticizer to form a wet material, with a ratio of 1 g: 1.5 ml.

[0063] S2.1 Disperse P-GO powder (preparation method is the same as in Example 1) in deionized water to prepare a suspension with a solid content of about 0.5 wt%, and sonicate for 15 min to fully disperse and stabilize it;

[0064] S2.2 Under the condition of continuous stirring of the wet material obtained in S1, the P-GO suspension is sprayed at a uniform speed according to the ratio of steel slag mass: P-GO suspension volume = 1g : 1.8mL, so that it is evenly coated on the surface of the steel slag to obtain mixture A.

[0065] S2.3 Select water glass (modulus 1.5) and dilute the water glass stock solution with deionized water to a Na2O equivalent concentration of 8wt%.

[0066] S3. Subsequently, while continuously stirring, water glass solution is slowly added dropwise, with the amount of water glass being 1.2 wt% of the steel slag (based on Na2O). Sodium sulfate (0.5 wt% of the steel slag) is added simultaneously while stirring to obtain mixture B.

[0067] S4. The mixture obtained above is heated to 80°C and kept at that temperature for 45 minutes in a closed reactor. After that, the product is placed in an oven and dried at 60°C for 2 hours to obtain modified steel slag.

[0068] S5. Mix coal gangue particles and sodium hydroxide solid powder at a mass ratio of 1:0.14 and stir evenly. Then heat to 650℃ in a muffle furnace and hold for 30 minutes. After completion, cool the product to room temperature and then perform mechanical grinding and sieving to obtain activated coal gangue with a particle size distribution between 0.1 and 0.15 mm.

[0069] S6. Take the following raw materials: 350 parts by weight of 42.5 ordinary Portland cement, 436 parts by weight of modified steel slag in this embodiment, 72 parts by weight of activated coal gangue in this embodiment, 92 parts by weight of Grade I fly ash, 42 parts by weight of silica fume, and 120 parts by weight of emulsified asphalt (Anhui Boyou New Material Co., Ltd.). First, mix the cement, modified steel slag, activated coal gangue, fly ash and silica fume and stir evenly. Then, add the emulsified asphalt and water to the obtained dry powder at a water-cement ratio of 0.3 and stir evenly to obtain the modified steel slag mixture.

[0070] Example 3

[0071] A modified steel slag, its preparation method, and its application, specifically:

[0072] S1. Steel slag fine aggregate with a particle size distribution between 0.2 and 0.5 mm is mixed with an aqueous solution (mass fraction 5%) of polycarboxylate superplasticizer to form a wet material, with a ratio of 1 g: 1.5 ml.

[0073] S2.1 Disperse P-GO powder (preparation method is the same as in Example 1) in deionized water to prepare a suspension with a solid content of about 0.5 wt%, and sonicate for 15 min to fully disperse and stabilize it;

[0074] S2.2 Under the condition of continuous stirring of the wet material obtained in S1, P-GO suspension is sprayed at a uniform speed according to the ratio of steel slag mass: P-GO suspension volume = 1g : 0.7mL, so that it is evenly coated on the surface of steel slag, and water glass is used to obtain mixture A.

[0075] S2.3 Dilute the stock solution of water glass (modulus 1.5) with deionized water to a solution with a Na2O equivalent concentration of 5wt%;

[0076] S3. Subsequently, while stirring continuously, water glass solution is slowly added dropwise, with the amount of Na2O being 0.8 wt% of the steel slag mass. Sodium sulfate (with the amount of Na2O being 1 wt% of the steel slag mass) is added simultaneously while stirring to obtain mixture B.

[0077] S4. The mixture obtained above is heated to 80°C and kept at that temperature for 45 minutes in a closed reactor. After that, the product is placed in an oven and dried at 60°C for 2 hours to obtain modified steel slag.

[0078] S5. Mix coal gangue particles and sodium hydroxide solid powder at a mass ratio of 1:0.14 and stir evenly. Then heat to 650℃ in a muffle furnace and hold for 30 minutes. After completion, cool the product to room temperature and then perform mechanical grinding and sieving to obtain activated coal gangue with a particle size distribution between 0.1 and 0.15 mm.

[0079] S6. Take the following raw materials: 332 parts by weight of 42.5 ordinary Portland cement, 420 parts by weight of modified steel slag in this embodiment, 68 parts by weight of activated coal gangue in this embodiment, 85 parts by weight of Grade I fly ash, 40 parts by weight of silica fume, and 120 parts by weight of emulsified asphalt (produced by Anhui Boyou New Materials Co., Ltd.). First, mix the cement, modified steel slag, activated coal gangue, fly ash and silica fume and stir evenly. Then, add the emulsified asphalt and water to the obtained dry powder at a water-cement ratio of 0.3 and stir evenly to obtain the modified steel slag mixture.

[0080] Comparative Example 1

[0081] This comparative example provides a modified steel slag, its preparation method, and its application. The difference between this comparative example and Example 1 is that it does not include water glass and sodium sulfate, while the other conditions are the same.

[0082] Under the above conditions, in the absence of water glass and sodium sulfate, the dissolution reaction initiated by P-GO anchoring to C2F cannot form an effective consumption loop, and the synergistic mechanism is disrupted. Specifically: although P-GO can still anchor to the C2F surface and capture Fe through Fe-OP bonds... 3+ However, due to the lack of water glass and sodium sulfate, it cannot be rapidly consumed and converted into C-(F)-SH gel and ettringite. The driving force for the rightward shift of the dissolution equilibrium of C2F, etc., is weakened, and the unconsumed Ca... 2+ This further inhibited the continued hydration of C2S. Ultimately, the amount of hydration products generated in the system decreased, leading to a decline in mechanical properties.

[0083] Comparative Example 2

[0084] This comparative example provides a modified steel slag, its preparation method, and its application. The difference between this comparative example and Example 1 is that the graphene oxide powder was not modified by organophosphates, while the other conditions are the same.

[0085] Under the above conditions, GO is very easy to desorb and undergo secondary aggregation to form aggregates. At the same time, the formation of hydration products is hindered. Due to the lack of P-GO-induced C-(F)-SH transition zone, the internal stress generated by delayed expansion cannot be effectively buffered and dissipated, which exacerbates volume instability.

[0086] Test Example 1

[0087] In this test example, the specimens prepared in the examples and comparative examples were placed in a curing chamber and cured under standard conditions for 7 days. The compressive strength of the specimens was then determined according to the "Test Method for Strength of Cement Mortar (ISO Method)" (GB / T17671-2021). Shrinkage was also tested (the 28-day drying shrinkage rate of the specimens was determined according to the test method specified in the JC / T2381-2016 Repair Mortar Industry Standard). The test results are shown in Tables 1 and 2.

[0088] Table 1. Compressive strength performance test

[0089]

[0090] Table 1 shows the compressive strength test results of the modified steel slag mixtures prepared in the various embodiments of the present invention and Comparative Example 1 at different ages (3d, 7d, 28d) under standard curing conditions. As can be seen from the data in Table 1, the modified steel slag mixtures prepared in Examples 1-3 of the present invention exhibit excellent compressive strength at all ages. In Example 2, the compressive strengths at 3d, 7d, and 28d reached 45MPa, 62MPa, and 75MPa, respectively, showing good early strength development and stable later strength growth. Examples 1 and 3 also showed similar excellent performance. Comparative Example 1 (lacking water glass and sodium sulfate) shows that the synergistic effect of water glass and sodium sulfate is the key factor in achieving early activation of steel slag activity. As can be seen from Table 1, the key improvement of the present invention lies in: P-GO is anchored to the C2F surface through Fe-OP covalent bonds, actively reducing interfacial Fe... 3+ The concentration forces the C2F dissolution equilibrium to shift continuously to the right, enabling it to be efficiently activated and participate in hydration at an early stage. Water glass provides [SiO4]. 4- SO4 provided by sodium sulfate 2- Rapid consumption of dissolved Fe within the micro-region of the interface 3+ and Ca 2+ It directly transforms into C-(F)-SH gel and ettringite. Under the above mechanism, the low concentration of ions near the interface is maintained, providing a driving force for the continuous dissolution of C2F and C2S, and solving the problems of dense mineral structure, slow hydration reaction and insufficient early strength of steel slag.

[0091] Table 2. Shrinkage performance test

[0092]

[0093] Table 2 shows the drying shrinkage test results of the modified steel slag mixtures prepared in Example 2 and Comparative Example 2 at 28 days. As can be seen from the data in Table 2, the 28-day drying shrinkage of the modified steel slag mixture prepared in Example 2 is only 280 × 10⁻⁶. -6The mixture prepared in Comparative Example 2 (graphene oxide without organophosphate modification) exhibited a drying shrinkage rate as high as 550 × 10⁻⁶ after 28 days. -6 Table 2 shows that after P-GO anchors on the steel slag surface, it induces the in-situ growth of hydration products on the steel slag surface. C-(F)-SH constructs a transition zone between the steel slag and cement stone. When f-CaO / f-MgO hydrates and expands, it can effectively buffer and dissipate stress, inhibiting the initiation and propagation of microcracks at the interface. Simultaneously, within the P-GO anchored area, water glass and sodium sulfate synergistically consume the Ca released by hydrolysis. 2+ This reduces the generation of expansion stress at its source.

[0094] The above technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included in the patent protection scope of the present invention.

Claims

1. A modified steel slag mixture, characterized in that, The raw materials for preparing the modified steel slag mixture include: modified steel slag, silicate cement, fly ash, silica fume, activated coal gangue, and emulsified asphalt. The raw materials for preparing the modified steel slag, by weight, include: 100-110 parts steel slag, 0.5-2.0 parts phosphate-modified graphene oxide, 5-10 parts polycarboxylate superplasticizer, 0.5-2.0 parts water glass, and 0.3-1.2 parts sodium sulfate. The raw materials for preparing the phosphate-modified graphene oxide include organic phosphate esters and graphene oxide.

2. The modified steel slag mixture according to claim 1, characterized in that, The raw materials for preparing the modified steel slag mixture, by weight, include: 330-370 parts by weight of silicate cement, 420-460 parts by weight of modified steel slag, 85-95 parts by weight of fly ash, 35-45 parts by weight of silica fume, 65-75 parts by weight of activated coal gangue, and 100-130 parts by weight of emulsified asphalt.

3. The modified steel slag mixture according to claim 1, characterized in that, The organic phosphate ester includes at least one of dibutyl phosphate and dioctyl phosphate.

4. A method for preparing a modified steel slag mixture as described in any one of claims 1 to 3, characterized in that, include: The modified steel slag mixture is obtained by mixing silicate cement, modified steel slag, activated coal gangue, fly ash, and silica fume, then adding emulsified asphalt and water, and reacting the mixture.

5. A preparation method as described in claim 4, characterized in that, The method for preparing the modified steel slag includes: S1. Mix the steel slag with the polycarboxylate superplasticizer to form a wet material; S2. The phosphate-modified graphene oxide is dispersed and then sprayed onto the wet material to obtain mixture A; S3. Mix the mixture A, the solution of the water glass, and the sodium sulfate to obtain mixture B; S4. The mixture B is heated and reacted, then dried to obtain the modified steel slag.

6. The preparation method according to claim 5, characterized in that, In step S4, the temperature of the heating reaction is 70~90℃, and the heating reaction time is 40~50min.

7. The preparation method according to claim 5, characterized in that, The preparation method of the phosphate ester modified graphene oxide includes: A1. After dispersing the graphene oxide, add the organic phosphate ester, mix and sonicate, then add xylene to obtain the reaction system; A2. The reaction system is heated to react. During the reaction, the generated water is removed by a water separator, and a mixed solvent composed of xylene and N,N-dimethylformamide is added to maintain the stability of the reaction system. A3. After the reaction is complete, the product is purified to obtain phosphate-modified graphene oxide.

8. The preparation method according to claim 7, characterized in that, In step A2, the temperature of the heating reaction is 120~150℃.

9. The application of a modified steel slag mixture as described in any one of claims 1 to 3 in concrete.

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