Non-structural anti-floating counterweight concrete using steel slag to replace all aggregates and preparation method thereof

Abstract

The present invention discloses a non-structural anti-floating weighted concrete in which all aggregates are replaced by steel slag, and a preparation method thereof. Calculated by mass, the anti-floating weighted concrete comprises: 100 parts of cement, 200-300 parts of fine aggregate steel slag, 450-500 parts of coarse aggregate steel slag, 10-50 parts of magnetic protective agent, 5-10 parts of retarder, and 1-2 parts of thickener. The present invention uses a magnetic protective agent to prevent water and carbon dioxide from entering the steel slag, thereby avoiding the expansion of the steel slag, so that the concrete after solidification is not easy to crack. At the same time, the performance of the concrete is improved by auxiliary agents such as retarder and thickener, the mixture has good fluidity and is easy to pump. The surface of the concrete after solidification is dense, dust-prone, and has good compressive strength, impact resistance, impermeability, and durability.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, in particular to a non-structural anti-floating weighted concrete using steel slag to replace all aggregates and a preparation method thereof. Background Art

[0002] Steel slag is an industrial waste product emitted during the steelmaking process. Currently, its utilization rate is only 10% to 20%, resulting in significant land occupation and environmental pollution. However, due to its similar strength to natural sand and gravel and its low cost, steel slag is well-suited for use in construction projects. Guided by the concept of green development, society continues to explore the use of steel slag as an admixture or aggregate in concrete. This reduces land occupation and environmental pollution caused by industrial waste while also lowering the material cost of concrete, in line with the development philosophy of reducing, recycling, and harmlessly disposing of solid and hazardous waste.

[0003] However, when steel slag is added to concrete, the CaO and MgO in the slag easily react with water and CO2 to produce calcium carbonate, magnesium carbonate, etc. Especially after the concrete solidifies, the CaO and MgO in the steel slag will also react with the water and carbon dioxide that penetrate into the concrete, causing the steel slag to expand, which can cause the concrete to crack, which limits the application of steel slag in concrete.

[0004] Chinese patent CN115504724A discloses a method for preparing concrete by adding a stabilizer and replacing coarse aggregate with steel slag. The method uses ferric chloride to suppress the expansion and cracking of the steel slag aggregate caused by alkaline reaction. Since the patent does not provide a technical principle or comparative test data, it is difficult to believe the technical effect achieved.

[0005] Chinese patent CN116239350A discloses a concrete that resists temperature-induced cracking. The modified steel slag particles are modified by grafting polyacrylic acid chains onto their surfaces. This results in modified slag particles that are less susceptible to polycarboxylate superplasticizer adsorption. This allows the polycarboxylate superplasticizer to fully exert its retarding properties, reducing the concentration of Portland cement hydration heat release and improving the suppression of temperature-induced cracking in concrete. However, this patented technology does not address the expansion of the steel slag itself. Summary of the Invention

[0006] The object of the present invention is to provide a non-structural anti-floating counterweight concrete and a preparation method thereof in order to solve the above-mentioned problems and to address the deficiencies of the prior art.

[0007] The technical solution adopted by the present invention is as follows: a non-structural anti-floating weighted concrete in which steel slag can replace all aggregates. Calculated by mass, the anti-floating weighted concrete comprises: 100 parts of cement, 200-300 parts of fine aggregate steel slag, 450-500 parts of coarse aggregate steel slag, 10-50 parts of magnetic protective agent, 5-10 parts of retarder and 1-2 parts of thickener.

[0008] In the present invention, fine aggregate steel slag and coarse aggregate steel slag completely replace conventional sand and gravel fine aggregate and coarse aggregate, which can not only reduce the occupation of land and environmental pollution caused by industrial waste steel slag, but also reduce the material cost of concrete, which is in line with the development direction of solid waste and hazardous waste reduction, resource utilization, and harmlessness. Since components such as CaO and MgO in steel slag easily react with water and CO2 to generate calcium carbonate, magnesium carbonate, etc., causing the steel slag to expand, which can cause concrete cracking, the present invention adds a magnetic protective agent to the concrete, utilizes the small amount of iron contained in the steel slag, allows the magnetic protective agent to be adsorbed on the surface of the steel slag, and combines the filling effect and water repellent effect of the magnetic protective agent to prevent water and carbon dioxide from penetrating into the steel slag, effectively preventing the reaction expansion of the steel slag, making it less likely for the solidified concrete to crack, and solving the problem of steel slag concrete being prone to expansion and cracking.

[0009] Furthermore, during the concrete slurry mixing process, before the magnetic protective agent covers the steel slag, water infiltrates the slag, triggering a hydration reaction. However, since the concrete is not yet solidified at this time, the hydration reaction of the steel slag will hardly cause cracking in the concrete. The retarder can prolong the setting time of the concrete, allowing the hydration reaction of the steel slag covering the magnetic protective layer to fully complete. After the concrete solidifies, the steel slag no longer expands, significantly reducing the probability of concrete cracking. Furthermore, because steel slag has a higher density than typical sand and gravel aggregates, the addition of a thickener increases the consistency of the slurry, weakens the agglomeration of the magnetic protective agent, and enhances the slurry's ability to wrap and support the steel slag aggregate, improving the uniformity of the aggregate dispersion. The resulting solidified concrete possesses excellent impermeability, compressive strength, crack resistance, and impact resistance. The denser concrete also increases resistance to the intrusion of H₂O and CO₂ into the concrete, further protecting the steel slag and the calcium hydroxide in the concrete. These synergistic effects alleviate the expansion and cracking issues of steel slag concrete.

[0010] Furthermore, the magnetic protective agent can be polyferric sulfate and / or ferroferric oxide. Polyferric sulfate is soluble in water and covers the surface of the steel slag in a molecular state, forming a dense protective film with good protective effect. Ferroferric oxide is insoluble in water and has a larger particle size than polyferric sulfate. However, since ferroferric oxide does not absorb water, the coating on the surface of the steel slag has good water repellency and can effectively prevent the steel slag from swelling due to water absorption reaction.

[0011] Further, the particle diameter of the ferroferric oxide is 10-30nm, for example, it can be 10nm, 15nm, 20nm, 30nm etc. The ferroferric oxide of this particle diameter has stable magnetism, and can preferably cover on the surface of the slag, plays a protective role. Nanoscale ferroferric oxide particles are small, and there is attraction and repulsion between the ferroferric oxide particles. Generally speaking, attraction is less, and it is not easy to reunite, but it can be adsorbed on the surface of the slag of larger pieces. Due to containing a small amount of simple iron (generally containing 2-8wt% simple iron) in the slag, the ferroferric oxide amount layer thickness adsorbed on the slag surface is suitable, and the ferroferric oxide is evenly distributed on the slag surface, which can better protect the slag.

[0012] Furthermore, the anti-floating counterweight concrete also includes a dispersant, the mass fraction of which is 1-2 parts, for example, 1 part, 1.2 parts, 1.5 parts, 2 parts, etc. Preferably, the dispersant is ethylene bisstearamide. Ethylene bisstearamide has a central hydrophilic group and long hydrophobic groups at both ends, and has the functions of dispersing cement and steel slag, as well as lubricating properties, which can improve the workability of the slurry and maintain a good slump. Ethylene bisstearamide can also further reduce the agglomeration and inclusion effects of the magnetic protective agent, promote the uniform dispersion of the magnetic protective agent, and ensure that the magnetic protective agent can be evenly covered on the surface of the steel slag.

[0013] Furthermore, the anti-floating counterweight concrete further comprises a grinding aid, the mass fraction of which is 0.5-1 parts, for example, 0.5 parts, 0.6 parts, 0.8 parts, 1 parts, etc. Preferably, the grinding aid is diethanol monoisopropanolamine. Diethanol monoisopropanolamine can improve the fluidity of the slurry, promote the dispersion and mutual adsorption of steel slag and magnetic protective agent, and also improve the early and late compressive strengths of the concrete.

[0014] Furthermore, the retarder is sodium gluconate and / or lignin sulfonate; the thickener is diutan gum and / or aluminum hydroxide. The sodium gluconate and / or lignin sulfonate have an appropriate retarding time, which not only allows for complete hydration of the steel slag but also promotes the timely setting of the concrete after the slag is fully hydrated. Diutan gum and aluminum hydroxide thicken the concrete slurry, improving the suspension stability of the steel slag. Diutan gum also has a film-forming effect, enhancing the stability of the magnetic protective agent coating on the steel slag surface.

[0015] Furthermore, the particle size of the fine aggregate steel slag is 2-5 mm, and the particle size of the coarse aggregate steel slag is 5-10 mm. Since the density of steel slag is greater than that of sand and gravel, it is easier for steel slag to settle in the slurry. If the particle size difference between the fine aggregate steel slag and the coarse aggregate steel slag is too large, segregation of coarse and fine aggregates is likely to occur. Using fine aggregate steel slag and coarse aggregate steel slag of the above particle size, they are more evenly dispersed, which also improves the uniformity of coverage of the magnetic protective agent. Steel slag of the above particle size can be prepared by crushing and screening.

[0016] Furthermore, the apparent density of the fine aggregate steel slag is 3.5-3.9 g / cm 3 The apparent density of the coarse aggregate steel slag is 3.0-3.4 g / cm 3 Coarse aggregate particles are heavier, while fine aggregate particles are lighter. Choosing the coarse aggregate steel slag with a slightly lower apparent density than the fine aggregate steel slag reduces the mass difference between the coarse and fine aggregate particles, making it easier to mix them evenly through stirring. Both coarse and fine aggregates are easily encapsulated and floated by the cement paste. If the apparent density difference between the coarse and fine aggregates is too large, segregation and stratification are likely to occur.

[0017] Furthermore, the present invention also includes a method for preparing the above-mentioned anti-floating counterweight concrete, comprising the following steps:

[0018] A. Crushing the steel slag and screening to obtain fine aggregate steel slag and coarse aggregate steel slag for standby use;

[0019] B. Weigh the measured components, then add the designed amount of water to mix and stir the components evenly to obtain the mixture, which is then poured.

[0020] In summary, due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0021] 1. Completely replacing conventional sand and gravel fine aggregate and coarse aggregate with fine aggregate steel slag and coarse aggregate steel slag can not only reduce the land occupation and environmental pollution caused by industrial waste steel slag, but also reduce the material cost of concrete, which is in line with the development direction of solid waste and hazardous waste reduction, resource utilization and harmlessness;

[0022] 2. The present invention solves the problem of concrete cracking caused by steel slag expansion by using a magnetic protective agent. The obtained steel slag concrete has good fluidity after adding water and stirring, and is easy to pump. The surface of the concrete after solidification is dense, with little dust, and has good compressive strength, impact resistance, impermeability and durability. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0024] Example

[0025] Example: Steel slag anti-floating counterweight concrete was prepared. The raw materials, calculated by mass, included 100 parts of cement, 200-300 parts of fine aggregate steel slag, 450-500 parts of coarse aggregate steel slag, 10-50 parts of magnetic protective agent, 5-10 parts of retarder, 1-2 parts of thickener, 0-2 parts of dispersant, and 0-1 part of grinding aid. The concrete was specifically prepared according to the formulas in Tables 1 and 2 below. The preparation method includes the following steps:

[0026] A. Crushing the steel slag and screening to obtain fine aggregate steel slag and coarse aggregate steel slag for standby use;

[0027] B. Weigh the measured components, then add the designed amount of water to mix and stir the components evenly to obtain the mixture, which is then poured.

[0028] Table 1: Proportions of Anti-Floating Counterweight Concrete in Examples 1-8 (parts by mass)

[0029]

[0030] Table 2 Proportions of Anti-floating Counterweight Concrete in Examples 9-16 (parts by mass)

[0031]

[0032] The particle size of the fine aggregate steel slag in the above Examples 1-16 is 2-5 mm, and the apparent density of the fine aggregate steel slag is 3.5-3.9 g / cm 3 The particle size of coarse aggregate steel slag is 5-10mm, and the apparent density of coarse aggregate steel slag is 3.0-3.4g / cm 3 The particle size of ferrosoferric oxide is 10-30 nm, and the iron content of the fine aggregate steel slag and the coarse aggregate steel slag is 2-8 wt%.

[0033] Comparative Example

[0034] Comparative Example: Steel slag anti-floating counterweight concrete was prepared. The raw materials included, by mass, 100 parts of cement, 200-300 parts of fine aggregate steel slag, 450-500 parts of coarse aggregate steel slag, 0-50 parts of magnetic protective agent, 0-10 parts of retarder, and 0-2 parts of thickener. The concrete was specifically configured according to the formulas in Tables 3 and 4 below, and the preparation method was the same as that in the embodiment.

[0035] Table 3 Comparative Examples 1-6 Anti-floating Counterweight Concrete Proportions (Parts by Mass)

[0036]

[0037] Table 4 Comparative Examples 7-12 Anti-floating weighted concrete mix ratio (parts by mass)

[0038]

[0039]

[0040] The particle size of the fine aggregate steel slag in the above comparative examples 1-12 is 2-5 mm, and the apparent density of the fine aggregate steel slag is 3.5-3.9 g / cm 3 The particle size of coarse aggregate steel slag is 5-10mm, and the apparent density of coarse aggregate steel slag is 3.0-3.4g / cm 3 The particle size of ferrosoferric oxide is 10-30 nm, and the iron content of the fine aggregate steel slag and the coarse aggregate steel slag is 2-8 wt%.

[0041] Comparative Example 13: The proportions are the same as those in Example 1, except that the particle size of the fine aggregate steel slag in this comparative example is 0.2-1 mm, and the particle size of the coarse aggregate steel slag is 15-25 mm.

[0042] Comparative Example 14: The proportions are the same as those in Example 1, except that the apparent density of the fine aggregate steel slag in this comparative example is 3.0-3.1 g / cm 3 The apparent density of coarse aggregate steel slag is 3.8-3.9g / cm 3 .

[0043] Comparative Example 15: The proportions are the same as those in Example 9, except that the particle size of the ferrosoferric oxide in this comparative example is 50-100 nm.

[0044] Comparative Example 16: The proportions are the same as those of Example 9, except that the iron content of the fine aggregate steel slag and the coarse aggregate steel slag in this comparative example is 15-20%.

[0045] Experimental testing

[0046] 50 parts by weight of water was added to each of the concretes prepared in Examples 1-16 and Comparative Examples 1-16, and the mixture was stirred and mixed uniformly to prepare various test specimens. The compressive strength, apparent density, slump, crack resistance, impermeability, chloride ion migration coefficient, and first crack impact times of each sample were tested. The test methods and reference standards for the expression of test results for each test item are as follows:

[0047] Compressive strength: The test method refers to "GB / T 50081-2019 Standard for Test Methods of Physical and Mechanical Properties of Concrete".

[0048] Apparent density: For the detection method, refer to GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures.

[0049] Slump: The detection method refers to GB / T 50080-2016 Standard for Test Methods of Performance of Ordinary Concrete Mixtures.

[0050] Crack resistance: The detection method refers to GB / T 50082-2009 Standard for test methods of long-term performance and durability of ordinary concrete.

[0051] Water-resistance grade: The water-resistance grade of concrete is tested according to 6.2 step-by-step pressure method in GB / T50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete".

[0052] Chloride ion migration coefficient: in accordance with 7.1 rapid chloride ion migration coefficient method in GB / T50082-2009 "Standard for test methods of long-term performance and durability of ordinary concrete".

[0053] Number of first crack impacts: refer to the drop hammer method in CECS13-2009 "Fiber Concrete Test Method Standard".

[0054] The test results of the above test items for the concrete prepared in Examples 1-16 and Comparative Examples 1-16 are shown in Tables 5 and 6 below.

[0055] Table 5 Performance test results of concrete prepared by Examples 1-16 and Comparative Examples 1-16

[0056]

[0057]

[0058] Table 6 Test results of concrete properties prepared by Examples 1-16 and Comparative Examples 1-16

[0059]

[0060]

[0061] From the results in Tables 5 and 6, we can see that:

[0062] The compressive strength, apparent density, slump, crack resistance, impermeability grade, chloride ion penetration resistance, and initial crack impact times of the concrete samples of Examples 1-16 are generally stronger than those of the samples of Comparative Examples 1-16, indicating that the scheme of Examples 1-16 can achieve better concrete performance effects;

[0063] Compared with Examples 1-3, Examples 4-5, and Examples 12-13 compared with Examples 9-11, added dispersants to the raw materials of the concrete, and the slump, crack resistance, impermeability, resistance to chloride ion penetration, and the number of initial crack impacts of the concrete were all improved. This is because the dispersant ethylene bisstearamide has a middle hydrophilic group and long hydrophobic groups at both ends, which has the function of dispersing cement and steel slag, and also has a lubricating effect, thereby improving the workability of the slurry, maintaining a good slump of the slurry, and promoting the uniform dispersion of the magnetic protective agent, so that the magnetic protective agent can be evenly covered on the surface of the steel slag;

[0064] Compared with Examples 1-3, Examples 6-7, and Examples 14-15 compared with Examples 9-11, added grinding aids to the raw materials of concrete, and the compressive strength of the concrete was significantly improved. This is because the grinding aid diethanol monoisopropanolamine can improve the fluidity of the slurry, promote the dispersion and mutual adsorption of steel slag and magnetic protective agent, and also improve the early and late compressive strengths of the concrete.

[0065] In Example 8 compared to Example 2, and in Example 16 compared to Example 10, dispersants and grinding aids were added to the raw materials of the concrete, and the compressive strength, slump, crack resistance, impermeability grade, resistance to chloride ion penetration, and number of initial crack impacts of the concrete were all improved;

[0066] Comparative Examples 1-2 compared to Examples 1-3, and Comparative Examples 7-8 compared to Examples 9-11, where no or little magnetic protective agent was added, showed a significant decrease in the compressive strength, slump, crack resistance, impermeability grade, chloride ion penetration resistance, and initial crack impact times of the concrete. This is because the magnetic protective agent can be adsorbed on the surface of the steel slag, preventing water and carbon dioxide from further invading the steel slag, effectively preventing the reaction and expansion of the steel slag, and making the cured concrete less likely to crack.

[0067] Comparative Examples 3-4 compared to Examples 1-3, and Comparative Examples 9-10 compared to Examples 9-11, did not add or added less retarder, and the compressive strength, slump, crack resistance, impermeability grade, chloride ion penetration resistance, and initial crack impact times of the concrete all decreased. This is because the retarder can extend the setting time of the concrete, allowing the hydration reaction of the steel slag covering the magnetic protective layer to be fully completed. After the concrete solidifies, the steel slag no longer expands, greatly reducing the probability of concrete cracking.

[0068] Comparative Examples 5-6 compared to Examples 1-3, and Comparative Examples 11-12 compared to Examples 9-11, showed a decrease in the compressive strength, slump, crack resistance, impermeability rating, resistance to chloride ion penetration, and number of initial crack impacts of the concrete, with no or minimal thickener added. This is because the addition of the thickener increased the consistency of the slurry, improving the slurry's ability to wrap and support the steel slag aggregate, and enhancing the uniformity of aggregate dispersion. The resulting solidified concrete exhibited excellent impermeability, compressive strength, crack resistance, and impact resistance. The dense concrete also increased resistance to the intrusion of H2O and CO2 into the concrete, further protecting the calcium hydroxide and other components in the steel slag and concrete.

[0069] In Comparative Example 13, compared to Example 1, smaller-sized fine aggregate steel slag and larger-sized coarse aggregate steel slag were used. The particle size of the fine aggregate steel slag was 0.2-1 mm, and the particle size of the coarse aggregate steel slag was 15-25 mm. The compressive strength, slump, crack resistance, impermeability grade, chloride ion penetration resistance, and first crack impact times of the concrete all decreased. This was mainly because the particle size difference between the fine aggregate steel slag and the coarse aggregate steel slag was too large, which easily caused sedimentation and uneven mixing, affecting the performance of the concrete.

[0070] Compared with Example 1, in Comparative Example 14, the apparent density of the fine aggregate steel slag was changed to be less than that of the coarse aggregate steel slag, which made the coarse aggregate steel slag easier to settle. The compressive strength, slump, crack resistance, impermeability grade, resistance to chloride ion penetration, and first crack impact number of the concrete were significantly reduced.

[0071] Compared with Example 9, in Comparative Example 15, the particle size of ferrosoferric oxide increased from 10-30 nm to 50-100 nm, which prevented it from evenly covering the surface of the steel slag, weakening the protective effect on the steel slag. This resulted in a decrease in the compressive strength, slump, crack resistance, impermeability, chloride ion penetration resistance, and initial crack impact times of the concrete.

[0072] Compared with Example 9, in Comparative Example 16, the iron content of the fine aggregate steel slag and the coarse aggregate steel slag was increased to 15-20 wt %. The ferroferric oxide adsorbed by the steel slag increased and aggregated, and the adsorption layer was thick and uneven, resulting in a slight decrease in the compressive strength, slump, crack resistance, impermeability grade, chloride ion penetration resistance, and initial crack impact number of the concrete.

[0073] In summary, the concrete prepared in Examples 1-16 exhibited excellent workability, meeting the requirements for pumping construction. Its compressive strength, workability, crack resistance, impermeability, and impact resistance were superior to those of the comparative example. The anti-floating weighted concrete prepared in Examples 1-16 exhibited excellent impermeability, effectively preventing water and moisture from penetrating the concrete. The concrete was also resistant to aging and corrosion, making it suitable for use in basements or underwater environments.

[0074] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A non-structural anti-floating weighted concrete using steel slag to replace all aggregates, characterized in that: Calculated by mass, the anti-floating counterweight concrete includes: 100 parts of cement, 200-300 parts of fine aggregate steel slag, 450-500 parts of coarse aggregate steel slag, 10-50 parts of magnetic protective agent, 5-10 parts of retarder and 1-2 parts of thickener.

2. The anti-floating weighted concrete according to claim 1, characterized in that: The magnetic protective agent is polyferric sulfate and / or ferrosoferric oxide.

3. The anti-floating weighted concrete according to claim 2, characterized in that: The particle size of the ferrosoferric oxide is 10-30 nm.

4. The anti-floating weighted concrete according to claim 1, characterized in that: The anti-floating weighted concrete further comprises a dispersant, and the mass portion of the dispersant is 1-2 parts.

5. The anti-floating weighted concrete according to claim 4, characterized in that: The anti-floating weighted concrete further comprises a grinding aid, and the mass portion of the grinding aid is 0.5-1 part.

6. The anti-floating weighted concrete according to claim 5, characterized in that: The dispersant is ethylene bisstearamide; and the grinding aid is diethanol monoisopropanolamine.

7. The anti-floating weighted concrete according to claim 6, characterized in that: The retarder is sodium gluconate and / or lignin sulfonate; the thickener is diutan gum and / or aluminum hydroxide.

8. The anti-floating weighted concrete according to any one of claims 1 to 7, characterized in that: The particle size of the fine aggregate steel slag is 2-5 mm, and the particle size of the coarse aggregate steel slag is 5-10 mm.

9. The anti-floating weighted concrete according to claim 8, characterized in that: The apparent density of the fine aggregate steel slag is 3.5-3.9 g / cm 3 The apparent density of the coarse aggregate steel slag is 3.0-3.4 g / cm 3 .

10. A method for preparing the anti-floating counterweight concrete according to any one of claims 1 to 9, characterized in that: The steps include: A. Crushing the steel slag and screening to obtain fine aggregate steel slag and coarse aggregate steel slag for standby use; B. Weigh the measured components, then add the designed amount of water to mix and stir the components evenly to obtain the mixture, which is then poured.

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