A high-strength solid waste-based magnesium phosphate grouting slurry and preparation method

Abstract

The invention discloses a high-strength solid waste-based magnesium phosphate grouting slurry and a preparation method. The solid waste-based material raw materials include: 8-13 parts of red mud, 8-14 parts of shell powder, 8-14 parts of coral sand, 9-10 parts of fly ash, 6-8 parts of carbide slag, 5-6 parts of slag, 4-5 parts of steel slag, 0-3 parts of boron oxide, 2-3 parts of borax, and 1.5-2 parts of chitosan film; the magnesium phosphate gelling material raw materials include: 8-13 parts of C4AF solid solution, 13-16 parts of magnesium oxide, and 5-6 parts of phosphate; the composite admixture consists of admixture I and admixture II, wherein the raw materials of admixture I include: 0.3-2 parts of water reducer and 5-10 parts of xanthan gum; the raw materials of admixture II include: 0.2-3.8 parts of chopped fiber and 1-2 parts of roasted hydrotalcite; and the amount of seawater used satisfies a water-to-binder ratio of 0.8:1-1.5:1. The particle size ranges of some components are: red mud <75μm, shell powder 120-150μm, fly ash <45μm, carbide slag 10-50μm, slag 0-60μm, and steel slag 0-50μm. This invention aims to utilize industrial solid waste, shallow-sea waste materials, and seawater to prepare a high-strength solid waste-based magnesium phosphate grouting slurry for application in coastal, island, reef, and water conservancy engineering disaster prevention and control.

Description

Technical Field

[0001] The present invention relates to the field of marine civil engineering grouting materials, in particular to a high-strength solid waste-based magnesium phosphate grouting slurry and a preparation method thereof, belonging to the technical field of marine civil engineering grouting. Background Art

[0002] my country's South China Sea region is dotted with numerous islands, most of which, particularly those along the coastline and their submarine areas, are extremely strategic locations. Therefore, constructing residential buildings, border defense facilities, and transportation routes, as well as improving coastal or submarine foundations, in these areas is crucial. The geological conditions surrounding the coast, islands, reefs, and submarine areas are often rich in water, creating an extremely complex hydrogeological environment for these marine and water conservancy projects. Therefore, controlling adverse geological hazards is a pressing issue.

[0003] Grouting is a common method for disaster prevention and control in coastal, island, and water conservancy projects. Due to its ease of construction, low cost, and high efficiency, this method has been widely used in coastal, island, and water conservancy disasters. However, many problems still exist during the grouting process in coastal, island, and water conservancy projects.

[0004] (1) The magnesium phosphate cement currently available on the market has defects such as fast setting time, poor durability, easy pipe clogging, poor filling effect, poor strength and toughness, and poor impermeability.

[0005] (2) The disposal of bulk industrial solid waste and hazardous waste has become an emerging trend in the global low-carbon new materials industry. Currently, there are problems such as the low maturity of carbon reduction technologies related to cement products, high costs, and limited emission reductions.

[0006] (3) The existing magnesium phosphate cement does not make comprehensive use of slag and steel slag in solid waste, and does not consider the effect of the ball-milled particle size of solid waste on the performance of grouting materials.

[0007] (4) The existing magnesium phosphate cement is mainly composed of dead-burned magnesium oxide, phosphate and retarding material. Compared with silicate cement, the cost of its various components is high, which is the main factor restricting the sustainable development of this type of grouting material.

[0008] (5) Existing magnesium phosphate grouting materials do not systematically combine industrial solid waste, shallow sea waste, seawater, composite admixtures and slurry preparation parameters, and have not formed a complete process technology from comprehensive treatment of industrial solid waste and shallow sea waste to slurry preparation.

[0009] Based on the current problems of poor geological disaster control in coastal, island and reef and water conservancy project construction, it is very necessary to study a grouting slurry with high strength, early strength, anti-dispersion and rapid setting. On the basis of maintaining the original strength, a large amount of industrial solid waste, shallow sea waste materials and seawater can be recycled and reused, which not only solves the problems of difficult treatment of industrial solid waste, shallow sea or island and reef waste materials, but also achieves the effect of low-carbon protection. Summary of the Invention

[0010] The present invention provides a high-strength solid waste-based magnesium phosphate grouting slurry and its preparation method. This grouting slurry enables resource utilization of industrial solid waste, shallow sea or island reef waste materials, and seawater. It exhibits excellent hydration hardening properties, water resistance, underwater anti-dispersion properties, improved compressive strength, and rapid solidification. It can be used in various coastal, island, and water conservancy projects, meeting the requirements of green and economic marine civil engineering, and facilitating the construction of island and reef military defense facilities and the further development and utilization of marine resources.

[0011] To achieve the above object, the present invention adopts the following technical solutions:

[0012] A high-strength solid waste-based magnesium phosphate grouting slurry, composed of solid waste-based materials, magnesium phosphate gelling materials, and composite admixtures, wherein the solid waste-based materials are made of the following raw materials in parts by weight: 8-13 parts of red mud; 8-14 parts of shell powder; 8-14 parts of coral sand, 9-10 parts of fly ash, 6-8 parts of calcium carbide slag, 5-6 parts of slag, 4-5 parts of steel slag, 0.3 parts of boron oxide, 23 parts of borax, and 1.52 parts of chitosan film; the magnesium phosphate gelling material is made of the following raw materials in parts by weight: 8-13 parts of C4AF solid solution, 13-16 parts of magnesium oxide, 5-6 parts of phosphate parts; the composite admixture is composed of admixture I and admixture II, admixture I is made of the following raw materials in parts by weight: 0.3-2 parts of water reducer; 5-10 parts of anti-dispersant xanthan gum; admixture II is made of the following raw materials in parts by weight: 0.2-3.8 parts of chopped fiber; 1-2 parts of roasted hydrotalcite; the amount of seawater used meets the water-binder ratio of 0.8:1-1.5:1, and the particle size range of some components is red mud <75μm, shell powder 120-150μm, fly ash <45μm, carbide slag 10-50μm, slag 0-60μm, and steel slag 0-50μm.

[0013] Furthermore, the chitosan concentration is 0.01-0.04 g / mL, the chitosan film thickness is 0.2-0.5 mm, it is soft and porous, and its water absorption rate is more than 40 times its own weight.

[0014] Furthermore, the molecular weight of the xanthan gum is 200×10 4 -2000×10 4 .

[0015] Furthermore, the present invention utilizes the mineralization effect of the abundant alkali metal potassium and sodium in red mud on the C4AF solid solution, significantly lowering the formation temperature of the C4AF solid solution and further promoting the formation of large amounts of calcium ferroaluminate sulfide within the range of 1000-1300°C. This indicates that the C4AF solid solution has a relatively low formation temperature, demonstrating its significant low-carbon advantage.

[0016] Furthermore, a mixture of C4AF solid solution and magnesium oxide is then prepared into a magnesium phosphate cementitious material within a certain range of proportions. The former first undergoes a high-temperature chemical reaction to calcine the calcium and aluminum components in a certain chemical ratio to obtain the C4AF solid solution; the latter is prepared by calcining shell powder or coral sand and fly ash according to a certain stoichiometric ratio to obtain a mixture of C4AF solid solution and magnesium oxide.

[0017] Furthermore, the coral sand is a product of crushed natural coral reefs, wherein the CaCO3 content is greater than 97%. The shell powder is a powder obtained by grinding natural mussel shells, with a particle size of 120-150 μm. The fly ash is secondary ash, with a 45 μm sieve residue of 12-20%, a water requirement ratio of 95-100%, and a moisture content of ≤1%.

[0018] Furthermore, the introduction of C4AF solid solution can form new hydration products with phosphate and magnesium oxide, giving magnesium phosphate cementitious materials increased strength and improved water resistance, and even increased long-term oxidation strength in water, to a certain extent solving the problems of high energy consumption and poor water resistance of magnesium phosphate cementitious materials.

[0019] Furthermore, the steel slag powder is prepared from steel slag in accordance with YB / T 022-2008, with a CaO content of no less than 50%. The resulting steel slag is a byproduct of the steelmaking process, and its addition can improve the flexural strength and water corrosion resistance of cement. The present invention utilizes steel slag powder to reduce its particle size, increase its specific surface area, and further enhance cementitious properties.

[0020] Furthermore, the content of the effective component Ca(OH)2 in the carbide slag is 65-75%, and the carbide slag is the waste residue generated by the production of acetylene gas using calcium carbide in the chemical industry.

[0021] Furthermore, the phosphate is at least one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium monohydrogen phosphate and ammonium monohydrogen phosphate, or a combination thereof.

[0022] Furthermore, the magnesium oxide is dead-burned magnesium oxide with an average particle size of 36.61 μm and a magnesium oxide content of ≥92%. The introduction of boron oxide and borax during the preparation of magnesium oxide can reduce the activity of magnesium oxide at low temperatures, resulting in coarser magnesium oxide crystals and enabling low-temperature preparation of magnesium oxide, thus meeting the demand for dead-burned magnesium oxide in existing magnesium phosphate cement.

[0023] Furthermore, the chopped fibers are a mixture of chopped basalt fibers and chopped polypropylene fibers in a mass ratio of 2-3:1; the diameter of the chopped basalt fibers is 5-20 μm, the length of the monofilament is 3-20 mm, and the density is 1-3 g / cm 3 The diameter of the short-cut polypropylene fiber is 9-30 μm, the length of the monofilament is 3-8 mm, and the density is 1-2 g / cm 3 .

[0024] Furthermore, the calcined hydrotalcite has a mass percentage of 0.11.5%. The calcined hydrotalcite is adsorbed on the surface of the chopped fibers, reducing the entanglement of the chopped fibers during mixing and improving the dispersibility of the chopped fibers. At the same time, the calcined hydrotalcite can adsorb sulfate ions in seawater, thereby reducing the degree of damage caused by sulfate ions to the hardened cement paste and achieving the effect of improving the compressive strength of marine engineering.

[0025] Furthermore, the amount of seawater used satisfies a water-to-cement ratio of 0.8:1-1.5:1, the glue is the total mass of the solid waste-based material and the magnesium phosphate cementitious material, the water-to-cement ratio is the mass ratio of water to glue, and the added water is seawater, which comes from at least one of the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea.

[0026] Furthermore, the water reducing agent is a polycarboxylic acid-based high-performance water reducing agent with a water reduction rate of 20%.

[0027] The preparation method of the present invention comprises the following steps:

[0028] (1) stirring shell powder, coral sand and fly ash at a stirring rate of 350-450 r / min for 60-80 s to obtain a mixture I;

[0029] (2) stirring the mixture I, red mud, borax, and boron oxide at a stirring rate of 350-450 r / min for 60-80 s to obtain a mixture II;

[0030] (3) crushing and grinding carbide slag, slag, and steel slag respectively to meet the requirement that the residue on an 80 μm square sieve is ≤4% and the fineness is controlled to be below 75 μm, and stirring is carried out at a stirring rate of 500-600 r / min for 60-80 s to obtain precursor I;

[0031] (4) Precursor I was wrapped with a chitosan film to obtain Precursor II;

[0032] (5) Stirring the precursor II and the mixture II at a stirring rate of 500-600 r / min for 60-80 s to obtain a solid waste-based material

[0033] (6) stirring the C4AF solid solution and magnesium oxide at a stirring rate of 350-450 r / min for 60-80 s to obtain a raw material precursor;

[0034] (7) calcining the raw material precursor at 1000-1500°C for 20 min-3 h, taking it out and letting it cool naturally;

[0035] (8) The cooled raw meal precursor is crushed and ground separately to meet the requirement that the residue on an 80 μm square hole sieve is ≤4% and the fineness is controlled to be below 75 μm, thereby obtaining mixture III;

[0036] (9) uniformly mixing the mixture III with the phosphate to obtain a magnesium phosphate gel material, drying it and placing it at room temperature for later use;

[0037] (10) Mixing the anti-dispersant xanthan gum and the water reducing agent with a portion of the seawater, stirring at a stirring rate of 350-450 r / min for 20-30 s to obtain an admixture I solution;

[0038] (11) mixing the calcined hydrotalcite, chopped fibers, and a portion of seawater, and stirring at a stirring rate of 350-450 rpm for 20-30 seconds to obtain an admixture II solution;

[0039] (12) mixing the remaining seawater, the solid waste-based material, and the magnesium phosphate gelling material, and stirring at a stirring rate of 350-450 r / min for 120-140 s to obtain a mixture IV;

[0040] (13) adding the remaining seawater, the admixture I solution, and the admixture II solution to the mixture IV, and stirring at a stirring rate of 550-700 rpm for 120-150 seconds to obtain the slurry;

[0041] Furthermore, in step (12), the solid waste-based material and the magnesium phosphate gelling material are mixed at a water-binder ratio of 0.8:11:1. Within this range, the performance of the obtained slurry is better.

[0042] The beneficial effects of the present invention are:

[0043] 1. This invention combines magnesium phosphate cementitious materials with red mud to reduce the magnesium oxide content. Simultaneously, substances within the red mud react with phosphates to form an amorphous gel, which fills the pores and acts as a framework. Mining admixtures such as fly ash, slag, and steel slag modify the magnesium phosphate cementitious materials, extending setting time, increasing slurry fluidity and density, improving pore structure, filling pores, and reducing porosity, thereby enabling the recycling of industrial waste residues. From this perspective, the incorporation of industrial solid wastes such as red mud into magnesium phosphate cement has significant low-carbon implications.

[0044] 2. Magnesium phosphate cementitious materials react with an acid-base reaction, and their pH varies over a relatively wide range during hydration and hardening, typically fluctuating between 4.0 and 11.0. The alkali metal sodium and potassium in red mud are typically dissolved in the C4AF solid solution. This portion of sodium and potassium has little effect on the formation of struvite, the primary hydration product in magnesium phosphate cement, and improves the hydration and hardening properties of magnesium phosphate cement. The presence of alkali metal sodium and potassium in the C4AF solid solution increases the likelihood of lattice distortion during its formation, thereby promoting moisture retention and hydration activity.

[0045] 3. The synergistic effect of the precursor, calcined hydrotalcite, chitosan film, and chopped fibers reduces sulfate ion damage to the hardened cement paste, thereby improving the compressive strength of marine engineering applications. Carbide slag and steel slag, primarily composed of CaO and Ca(OH)2, protect against seawater erosion. Furthermore, the chitosan film coats the precursor, reducing premature dissolution and loss of the precursor. When the precursor reacts with sulfate ions, a dense calcium sulfate film forms. The chitosan film absorbs seawater and expands, causing the deposit to adhere tightly to cracks and enhancing the strength of the solid deposit. Simultaneously, the dense calcium sulfate film seals the crack surface, reducing the possibility of seawater re-entering the tempered cement solution. The interaction between the admixture precursor, chitosan film, and chopped fibers reduces sulfate ion damage to the cement paste, thereby improving the compressive strength of the grouting process.

[0046] 4. The present invention also achieves the synergistic production of C4AF solid solution and low-activity magnesium oxide. Generally, the magnesium oxide used in magnesium phosphate cement is dead-burned magnesium oxide, which requires a formation temperature as high as 1600°C to meet its low activity requirements. C4AF solid solution can be formed in large quantities at 1200-1400°C. The present invention introduces a small amount of B2O3 during the raw meal preparation process, significantly reducing the activity of magnesium oxide at lower temperatures and allowing it to crystallize into large grains. This allows the synergistic production of C4AF solid solution and low-activity magnesium oxide, while simultaneously introducing red mud and a small amount of boron oxide.

[0047] 5. The admixture uses the anti-water dispersant xanthan gum to achieve the anti-dispersion property of the slurry underwater, which allows the slurry to solidify underwater while having little and negligible impact on the performance of the grouting slurry. The adsorption behavior of xanthan gum on the particle surface is one of the factors affecting the rheological properties of the slurry. Cement particles are surface-active, and the molecular structure side chains of xanthan gum contain a large number of negative ion groups. These negative ion groups can change the potential of the cement particle surface, so xanthan gum can be adsorbed on the surface of the cement particles. The present invention has excellent rapid solidification, anti-dispersion performance, high strength, and low relative cost, which are unattainable by existing underwater grouting slurries in coastal construction.

[0048] 6. This patented technology systematically utilizes industrial solid waste, shallow sea waste, seawater, and composite admixtures to prepare a high-strength solid waste-based magnesium phosphate grouting slurry, and innovatively forms a complete process technology system from the comprehensive treatment of industrial solid waste and shallow sea waste, the preparation of magnesium phosphate cementitious materials to the preparation of fresh slurry, forming a systematic and sub-item innovation. The prepared high-strength solid waste-based magnesium phosphate grouting slurry can be well applied to the fields of coastal, island, reef, water conservancy and other engineering disaster prevention and control. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 This is a schematic diagram of a method for preparing high-strength solid waste-based magnesium phosphate grouting slurry. DETAILED DESCRIPTION

[0050] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention more clear, the embodiments of the present invention are further described in detail below in conjunction with the embodiments and drawings. It should be noted that the following detailed descriptions are illustrative and are intended to provide further explanation of the present application. Unless otherwise specified, all technical and scientific terms used herein have the same meaning as commonly understood by those of ordinary skill in the art to which this application belongs.

[0051] The reagents and bulk industrial raw materials used in the present invention are all commercially available conventional products without manufacturer indication. Unless otherwise specified, the test methods listed are well known to those skilled in the art and are not listed here one by one.

[0052] Example 1

[0053] A high-strength solid waste-based magnesium phosphate grouting slurry, which is composed of solid waste-based materials, magnesium phosphate cementitious materials, and composite admixtures. The solid waste-based materials are made from the following raw materials in parts by weight: 13 parts red mud; 8 parts shell powder; 8 parts coral sand; 9 parts fly ash; 6 parts carbide slag; 4 parts steel slag; 2 parts boron oxide; 2 parts chitosan film; the magnesium phosphate cementitious materials are made from the following raw materials in parts by weight: 8 parts C4AF solid solution, 13 parts magnesium oxide, and 5 parts phosphate; the composite admixture is made from the following raw materials in parts by weight: 1 part xanthan gum (anti-dispersant); 1 part calcined hydrotalcite; 2 parts chopped fiber; and 1 part water reducer. The amount of seawater used satisfies a water-to-cement ratio of 1:1. The preparation method of the present invention comprises the following steps:

[0054] (1) stirring shell powder, coral sand and fly ash at a stirring rate of 350-450 r / min for 60-80 s to obtain a mixture I;

[0055] (2) stirring the mixture I, red mud, borax, and boron oxide at a stirring rate of 350-450 r / min for 60-80 s to obtain a mixture II;

[0056] (3) crushing carbide slag, slag, and steel slag respectively, grinding them to meet the requirement that the residue on an 80 μm square sieve is ≤4%, and the fineness is controlled to be below 75 μm, and stirring is carried out at a stirring rate of 500-600 r / min for 60-80 s to obtain precursor I;

[0057] (4) Precursor I was wrapped with a chitosan film to obtain Precursor II;

[0058] (5) Stirring the precursor II and the mixture II at a stirring rate of 500-600 r / min for 60-80 s to obtain a solid waste-based material

[0059] (6) stirring the C4AF solid solution and magnesium oxide at a stirring rate of 350-450 r / min for 60-80 s to obtain a raw material precursor;

[0060] (7) calcining the raw material precursor at 1000-1500°C for 20 min-3 h, taking it out and letting it cool naturally;

[0061] (8) The cooled raw material precursors are crushed and ground to meet the requirement that the residue on an 80 μm square sieve is ≤4% and the fineness is controlled to be below 75 μm, thereby obtaining mixture III;

[0062] (9) uniformly mixing the mixture III with the phosphate to obtain a magnesium phosphate gel material, drying it and placing it at room temperature for later use;

[0063] (10) Mixing the anti-dispersant xanthan gum and the water reducing agent with a portion of the seawater, stirring at a stirring rate of 350-450 r / min for 20-30 s to obtain an admixture I solution;

[0064] (11) mixing the calcined hydrotalcite, chopped fibers, and a portion of seawater, and stirring at a stirring rate of 350-450 rpm for 20-30 seconds to obtain an admixture II solution;

[0065] (12) mixing the remaining seawater, the solid waste-based material, and the magnesium phosphate gelling material, and stirring at a stirring rate of 350-450 r / min for 120-140 s to obtain a mixture IV;

[0066] (13) The remaining seawater, the admixture I solution, and the admixture II solution are added to the mixture IV, and stirred at a stirring rate of 550-700 r / min for 120-150 s to obtain the slurry.

[0067] The obtained slurry was tested for its land compressive strength (MPa), water compressive strength (MPa), water-land strength ratio (%), and resistance to high-pressure dynamic water scouring retention rate (%), as follows:

[0068] Land compressive strength test method: refer to the test method of DLT5117-2000 "Test Procedure for Underwater Non-dispersible Concrete". The test adopts a cubic triple mold with a test mold size of 70.7mm×70.7mm×70.7mm. Pour the slurry evenly into the cubic triple mold. Place the test mold in a standard curing box for curing. When it reaches the corresponding age, the compressive strength is measured and the P is obtained. 陆地 .

[0069] Underwater compressive strength test method: refer to the test method of DLT5117-2000 "Underwater non-dispersible concrete test procedures", and use a cubic triple mold with a test mold size of 70.7mm×70.7mm×70.7mm. Pour the slurry evenly into the cubic triple mold. Place the test mold in a water tank containing NaCl solution for curing. After reaching the corresponding age, remove the specimen from the water and conduct a compressive strength test. The P 水中 .

[0070] The water-land strength ratio represents the water dispersion resistance of the grouting material. The water-land strength ratio calculation formula is:

[0071]

[0072] The results are shown in Table 1 below:

[0073] Table 1

[0074]

[0075] Example 2

[0076] A high-strength solid waste-based magnesium phosphate grouting slurry, which is composed of solid waste-based materials, magnesium phosphate cementitious materials, and composite admixtures. The solid waste-based materials are made from the following raw materials in parts by weight: 9 parts red mud; 8 parts shell powder; 8 parts coral sand; 9 parts fly ash; 6 parts calcium carbide slag; 4 parts steel slag; 3 parts boron oxide; 3 parts borax; 1.5 parts chitosan film; the magnesium phosphate cementitious materials are made from the following raw materials in parts by weight: 10 parts C4AF solid solution, 16 parts magnesium oxide, and 6 parts phosphate; the composite admixture is made from the following raw materials in parts by weight: 1 part anti-dispersant xanthan gum; 1 part roasted hydrotalcite; 2 parts chopped fiber; and 1 part water reducer. The amount of seawater used satisfies a water-to-cement ratio of 1:1. The slurry properties were tested according to the preparation of Example 1, and the results are shown in Table 2 below:

[0077] Table 2

[0078]

[0079] Comparative Example 1

[0080] A high-strength solid waste-based magnesium phosphate grouting slurry was prepared according to the formula and method of Example 1, except that the composite admixture did not contain the water-resistant dispersant xanthan gum. The properties of the slurry were tested according to the preparation of Example 1, and the results are shown in Table 3 below:

[0081] Table 3

[0082]

[0083] Comparative Example 2

[0084] A high-strength solid waste-based magnesium phosphate grouting slurry was prepared according to the formula and method of Example 1, except that the composite admixture did not contain chopped fibers. The properties of the slurry were tested according to the preparation of Example 1, and the results are shown in Table 4 below:

[0085] Table 4

[0086]

[0087] Comparative Example 3

[0088] This comparative example uses commercially available raw materials to prepare magnesium phosphate cement with a water-to-binder ratio of 1.0. Distilled water and conventional magnesium phosphate cement are stirred at a stirring rate of 550-700 rpm for 120-150 seconds to obtain a grouting slurry. The properties of the slurry were tested according to the preparation of Example 1, and the results are shown in Table 5 below:

[0089] Table 5

[0090]

[0091] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the scope of the patent application of the present invention should fall within the scope of the present invention.

Claims

1. A high-strength solid waste-based magnesium phosphate grouting slurry, comprising a solid waste-based material, a magnesium phosphate gelling material, a composite admixture, and seawater. The solid waste-based material is made from the following raw materials in parts by weight: 8-13 parts red mud; 8-14 parts shell powder; 8-14 parts coral sand, 9-10 parts fly ash, 6-8 parts carbide slag, 5-6 parts slag, 4-5 parts steel slag, 0-3 parts boron oxide, 2-3 parts borax, and 1.5-2 parts chitosan film; the magnesium phosphate gelling material is made from the following raw materials in parts by weight: 8-13 parts C4AF solid solution, 13-16 parts magnesium oxide, and 5-6 parts phosphate; the composite admixture is composed of admixture I and admixture II, and admixture I is made from the following raw materials in parts by weight: 0.3-2 parts water reducer; and 5-10 parts xanthan gum, an anti-dispersant. Admixture II is made of the following raw materials in parts by weight: 0.2-3.8 parts of chopped fiber; 1-2 parts of calcined hydrotalcite; seawater in an amount satisfying a water-binder ratio of 0.8:1-1.5:1; and the particle size ranges of some components are as follows: red mud <75 μm, shell powder 120-150 μm, fly ash <45 μm, carbide slag 10-50 μm, slag 0-60 μm, and steel slag 0-50 μm. The following steps are involved: (1) stirring shell powder, coral sand and fly ash at a stirring rate of 350-450 r / min for 60-80 s to obtain a mixture I; (2) stirring the mixture I, red mud, borax, and boron oxide at a stirring rate of 350-450 r / min for 60-80 s to obtain a mixture II; (3) crushing carbide slag, slag, and steel slag respectively, and grinding them to meet the requirement that the residue on an 80 μm square sieve is ≤4%, the fineness is controlled to be below 75 μm, and stirring is carried out at a stirring rate of 500-600 r / min for 60-80 s to obtain precursor I; (4) Precursor I was wrapped with chitosan film to obtain precursor II; (5) stirring the precursor II and the mixture II at a stirring rate of 500-600 r / min for 60-80 s to obtain a solid waste-based material; (6) stirring the C4AF solid solution and magnesium oxide at a stirring rate of 350-450 r / min for 60-80 s to obtain a raw material precursor; (7) calcining the raw material precursor at 1000-1500°C for 20 min-3 h, taking it out and letting it cool naturally; (8) crushing and grinding the cooled raw material precursor to meet the requirement that the residue on an 80 μm square sieve is ≤4% and the fineness is controlled to be below 75 μm, thereby obtaining mixture III; (9) uniformly mixing the mixture III with the phosphate to obtain a magnesium phosphate gel material, drying it and placing it at room temperature for later use; (10) Mixing the anti-dispersant xanthan gum and the water reducing agent with a portion of the seawater, stirring at a stirring rate of 350-450 r / min for 20-30 s to obtain an admixture I solution; (11) mixing the calcined hydrotalcite, chopped fibers, and a portion of seawater, and stirring at a stirring rate of 350-450 rpm for 20-30 seconds to obtain an admixture II solution; (12) mixing portions of the seawater, the solid waste-based material, and the magnesium phosphate gelling material, and stirring at a stirring rate of 350-450 rpm for 120-140 s to obtain a mixture IV; (13) The remaining seawater, the admixture I solution, and the admixture II solution are added to the mixture IV, and stirred at a stirring rate of 550-700 r / min for 120-150 s to obtain the slurry.

2. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 1, characterized in that: The red mud is high-iron and aluminum-rich red mud; the fly ash is ultrafine fly ash with a water requirement ratio of 95-100% and a water content of ≤1%; the content of the active ingredient CaO in the carbide slag is 65-75%; the specific surface area of ​​the steel slag powder is ≥350m 2 / kg, the content of free calcium oxide is ≤3%; the coral sand is the product of crushing natural coral reefs, wherein the CaCO3 content is greater than 97%; the shell powder is ground into powder from natural mussel shells, and the particle size is 120-150μm.

3. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 1, characterized in that: The C4AF solid solution is a solid solution of at least two of C2F, C6AF2, C4AF, and C6A2F, and its average stoichiometry is C4AF; the phosphate is at least one of potassium dihydrogen phosphate, ammonium dihydrogen phosphate, sodium dihydrogen phosphate, potassium monohydrogen phosphate, and ammonium monohydrogen phosphate.

4. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 1, characterized in that: The magnesium oxide is dead-burned magnesium oxide with an average particle size of 36.61 μm and a magnesium oxide content of ≥92%.

5. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 1, characterized in that: The water reducer is a polycarboxylic acid high-performance water reducer with a water reduction rate of 20%; the chopped fibers are a mixture of chopped basalt fibers and chopped polypropylene fibers in a mass ratio of 2:1-3:

1.

6. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 5, characterized in that: The chopped basalt fiber has a diameter of 5-20 μm, a single fiber length of 3-20 mm, and a density of 1-3 g / cm 3 The diameter of the short-cut polypropylene fiber is 9-30 μm, the length of the monofilament is 3-8 mm, and the density is 1-2 g / cm 3 .

7. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 1, characterized in that: The chitosan membrane has a thickness of 0.2-0.5 mm, a chitosan concentration of 0.01-0.04 g / mL, is soft and porous, and has a water absorption rate of more than 40 times its own weight; the xanthan gum has a molecular weight of 200×10 4 -2000×10 4 The mass percentage of the calcined hydrotalcite is 0.1-1.5%; the amount of seawater used satisfies a water-binder ratio of 0.8:1-1.5:1; and the seawater comes from at least one of the Bohai Sea, the Yellow Sea, the East China Sea, and the South China Sea.

8. The high-strength solid waste-based magnesium phosphate grouting slurry according to claim 1, characterized in that: The steel slag specimens were carbonized in the early stage. They were placed in an environment with a temperature of 20±1℃ and a relative humidity of 60%-80% for 60 minutes, and then placed in a carbonization reactor. 99.9% CO2 gas was introduced for carbonization curing. During the curing period, the CO2 partial pressure of the system was kept constant at 0.35MPa.

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