High-toughness magnesium phosphate cementing material and preparation method thereof
By incorporating waste tire rubber particles and sulfur tailings into magnesium phosphate cement and using a composite retarder, the brittleness and high cost of MPC were solved, enabling the preparation of high-toughness and high-strength magnesium phosphate cementitious materials and promoting the resource utilization of waste.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-12-20
- Publication Date
- 2026-03-13
AI Technical Summary
Traditional magnesium phosphate cement (MPC) is brittle, has poor toughness, sets and hardens quickly, is inconvenient to construct and has high cost, which limits its application in scenarios with high requirements for impact resistance and crack resistance.
Waste tire rubber granules and sulfur tailings are used as admixtures, combined with composite retarder borax and tetrasodium iminodisuccinate, which work synergistically to improve the toughness and setting time of MPC and reduce costs.
It significantly improves the toughness and strength of magnesium phosphate cementitious materials, prolongs the setting time, reduces the heat of hydration, realizes the high-value utilization of waste, and has a simple preparation process.
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Figure CN121651859A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of building materials technology. Background Technology
[0002] Magnesium phosphate cement (MPC) is a novel cementitious material characterized by rapid hardening, early strength, and excellent bonding properties, widely used in rapid repair and the solidification of hazardous substances. However, MPC has several drawbacks. First, traditional MPC is brittle and lacks toughness, limiting its application in scenarios requiring high impact resistance and crack resistance. Second, MPC hardens rapidly, causing inconvenience during construction. Third, the high cost of MPC raw materials leads to a high overall price for cement, further restricting its widespread use.
[0003] Rubber granules possess excellent toughness, impermeability, fatigue resistance, thermal insulation, and sound insulation properties. Incorporating rubber granules into magnesium phosphate cement can fill voids and constrain the formation and development of micro-cracks within the slurry. Due to the elasticity of rubber, its inclusion in cement can significantly improve the cement's impact resistance, transforming "brittle cement" into "tough cement." However, the introduction of rubber granules often leads to a decrease in cement slurry fluidity, severely affecting workability. Furthermore, the weak interfacial bonding between rubber particles and cement results in a significant decrease in MPC strength.
[0004] Sulfur concentrate tailings are the residual waste from the flotation process of sulfur concentrate to produce sulfur concentrate powder. Due to their high pozzolanic activity, they can be used as high-performance concrete admixtures, effectively improving the strength of concrete. XRD analysis shows that sulfur concentrate tailings contain actinolite (Fe, Mg, Ca, Na, Mn)7(Si, Al)8O. 22 (OH) 1.9 Calcium zeolite (CaO·Al2O3·2SiO2·4H2O), Fe2O3, Al2O3, aluminum oxalate (C6Al2O3) 12 The magnesium phosphate cement contains crystalline phases such as CaCO3, iron alum (FeAl2(SO4)4·22H2O), etc. Among these, calcium zeolite belongs to the category of aluminosilicates and can react with ammonium dihydrogen phosphate at certain temperatures to form amorphous silica-alumina phosphate gel. This "active effect" and "micro-aggregate effect" enhance the strength of magnesium phosphate cement. This invention effectively extends the setting time and reduces the heat of hydration through the synergistic effect of multiple components, including a composite retarder, waste tire rubber particles, and sulfur tailings admixtures. This ensures high strength while improving toughness, achieving high-value-added resource utilization of waste tires and sulfur tailings. The use of rubber particles to toughen and modify magnesium phosphate cementitious materials results in good dispersibility, a simple preparation process, and low cost, facilitating widespread application. Summary of the Invention
[0005] The purpose of this invention is to provide a high-toughness magnesium phosphate cementitious material. Through the synergistic effect of composite retarder and multi-source admixtures, the toughness of MPC is significantly improved while maintaining high strength, the setting time of MPC is delayed, the raw material cost is reduced, and the resource utilization of waste tires and sulfur concentrate tailings is realized.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A high-toughness magnesium phosphate cementitious material is composed of the following raw materials: calcined magnesium oxide, dihydrogen phosphate, composite retarder (borax + tetrasodium iminodisuccinate), and solid waste admixtures (waste tire rubber granules and sulfur tailings). The mass ratio of the raw materials is as follows: dihydrogen phosphate: 100 parts; calcined magnesium oxide: 195-255 parts; solid waste admixtures: 45-105 parts; retarder: 12-21 parts; water content: 14-18% of the total solid mass.
[0008] In the above scheme, the total mass ratio of the recalcined magnesium oxide and solid waste admixture to the mass ratio of ammonium dihydrogen phosphate is 3:1.
[0009] In the above scheme, the solid waste admixture includes waste tire rubber particles and sulfur tailings, accounting for 15-35% of the total mass of calcined magnesium oxide and solid waste admixture, of which rubber particles: 30-60 parts, accounting for 10-20%; sulfur tailings: 15-45 parts, accounting for 5-15%.
[0010] In the above scheme, the composite retarder includes borax and tetrasodium iminodisuccinate, with a mass ratio of borax to tetrasodium iminodisuccinate of 1:1, and the amount of retarder accounts for 4-7% of the total mass of reburned magnesium oxide and solid waste admixture.
[0011] In the above scheme, the waste tire rubber particles have a particle size of 60-100 mesh and are derived from commercially available crushed waste tire particles. Before use, the following modification method is adopted: the commercially available crushed waste tire particles are soaked in a 5-10% NaOH aqueous solution for 2-8 hours, filtered, washed with deionized water until neutral, and dried at 80°C to constant weight. Then, the dried rubber particles are added to a mixing pot, and 2-3% silane coupling agent ethanol-water solution is sprayed into the mixing pot while stirring for 30 minutes. The particles are then dried to obtain modified rubber particles.
[0012] In the above scheme, the sulfur concentrate tailings are the residual waste from the production of sulfur concentrate powder by sulfur concentrate flotation. They are grayish-green powders that are dried and ground before use, with a specific surface area of 1300-1500 m². 2 / kg.
[0013] In the above scheme, the recalcined magnesia is produced by calcining magnesite at a high temperature of 1500-1600℃, wherein the magnesia content is 85%, the fineness is 300-400 mesh, and the specific surface area is 900-1000 m². 2 / kg.
[0014] In the above scheme, the borax is anhydrous borax with a purity greater than 95%.
[0015] In the above scheme, the purity of the tetrasodium iminodisuccinate is greater than 95%.
[0016] In the above scheme, the purity of the dihydrogen phosphate is greater than 99%.
[0017] The preparation method of the high-toughness magnesium phosphate cementitious material in the above scheme includes the following steps:
[0018] First, add water to the mixing pot according to the standard consistency water volume. Then, quickly add the mixture of calcined magnesium oxide, ammonium dihydrogen phosphate, retarder and solid waste admixture into the mixing pot within 5-10 seconds. Stir slowly for 2 minutes, stop for 15 seconds, scrape the slurry from the pot wall into the pot, and then stir quickly for 2 minutes to obtain a high-toughness magnesium phosphate cementitious material.
[0019] The properties of the high-toughness magnesium phosphate cementitious material obtained according to the above scheme are as follows: In all examples, the setting time is greater than 15 min; the 1.5 h compressive strength is greater than 28 MPa, the 1 d compressive strength is greater than 55 MPa, the 28 d compressive strength is greater than 90 MPa, and the fracture energy is greater than 90 N / m; In Example 4, the 1.5 h compressive strength is 35.2 MPa, the 1 d compressive strength is 62.8 MPa, and the 28 d compressive strength is 95.3 MPa, with the strength at each age increasing by 22.6%, 14.6%, and 11.6% respectively compared to Comparative Example 3; the fracture energy of Example 4 is 105.2 N / m, which is 60.4% higher than Comparative Example 1; the fluidity of the paste in Example 4 is 176 mm; the setting time is 15.0 min; considering both strength and fracture toughness, Example 4 is superior.
[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:
[0021] This invention uses waste tire rubber particles with a particle size of 60-100 mesh, which significantly improves the fracture energy and toughness of magnesium phosphate cementitious materials. Compared with other emulsion or fiber toughening methods, it has low cost, good dispersibility, and simple preparation process.
[0022] This invention incorporates sulfur tailings and rubber particles. Sulfur tailings can increase the fluidity of the slurry, while rubber particles can decrease the fluidity of the slurry. The sulfur tailings and rubber particles can achieve a reasonable particle size distribution, synergistically regulate the fluidity of the slurry, improve the strength of magnesium phosphate cementitious materials, reduce costs, and realize the high-value utilization of waste.
[0023] This invention uses waste tire rubber particles and sulfur tailings as admixtures, and borax and tetrasodium iminodisuccinate as composite retarder, which work synergistically to reduce the heat of hydration and regulate the setting time of the slurry. Attached Figure Description
[0024] Figure 1 Figures showing the compressive strength of the hydration products of each embodiment at 1.5h, 1d, and 28d.
[0025] Figure 2 Fracture energy diagrams of 28-day hydration products from various embodiments and comparative examples. Detailed Implementation
[0026] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the embodiments. The specific embodiments described herein are merely for explaining the invention and are not intended to limit the invention.
[0027] Unless otherwise specified, all reagents used in the following examples are commercially available chemical reagents.
[0028] Example 1
[0029] A high-toughness magnesium phosphate cementitious material, with the following raw material mass ratio: 100 parts of ammonium dihydrogen phosphate, 255 parts (85%) of calcined magnesium oxide, 30 parts (10%) of waste rubber granules (60 mesh), 15 parts (5%) of sulfur concentrate tailings, 10.5 parts of borax, 10.5 parts of tetrasodium iminodisuccinate, and 15% water.
[0030] The preparation process includes the following steps: First, weigh a certain amount of mixing water and pour it into a mixing pot. Then, within 10 seconds, add the weighed MPC mixture to the water. Place the pot on the mixer stand, raise it to the mixing position, start the mixer, and mix at low speed for 120 seconds. Stop for 15 seconds, scrape the cement slurry on the blades and pot wall into the center of the pot, and then mix at high speed for 120 seconds before stopping. Detect the fluidity. The standard consistency water volume is defined as the amount of water used when the slurry reaches a thickness of 175mm-185mm after 30 seconds ± 1 second of free flow. All examples use the standard consistency water volume to prepare the slurry.
[0031] The performance test results of the magnesium phosphate cementitious material obtained in this embodiment are as follows: the fluidity of the paste is 180 mm; the setting time is 15.5 min; the compressive strength at 1.5 h is 33.7 MPa, the compressive strength at 1 day is 63.4 MPa, the compressive strength at 28 days is 95.7 MPa, and the rupture energy is 92.4 N / m.
[0032] Example 2
[0033] A high-toughness magnesium phosphate cementitious material, the raw material mass ratio is as follows: ammonium dihydrogen phosphate: 100 parts, calcined magnesium oxide: 240 parts (80%), waste rubber particles (60 mesh): 30 parts (10%), sulfur concentrate tailings: 30 parts (10%), borax: 9.8 parts, tetrasodium iminodisuccinate: 9.8 parts, water content: 14%, the preparation process is the same as in Example 1.
[0034] The performance test results of the magnesium phosphate cementitious material obtained in this embodiment are as follows: the fluidity of the paste is 182 mm; the setting time is 16.0 min; the compressive strength at 1.5 h is 36.4 MPa, the compressive strength at 1 d is 66.5 MPa, the compressive strength at 28 d is 99.2 MPa, and the rupture energy is 94.5 N / m.
[0035] Example 3
[0036] A high-toughness magnesium phosphate cementitious material, the raw material mass ratio is as follows: ammonium dihydrogen phosphate: 100 parts, calcined magnesium oxide: 240 parts (80%), waste rubber particles (60 mesh): 37.5 parts (12.5%), sulfur concentrate tailings: 22.5 parts (7.5%), borax: 9.8 parts, tetrasodium aminodisuccinate: 9.8 parts, water content: 15%, the preparation process is the same as in Example 1.
[0037] The performance test results of the magnesium phosphate cementitious material obtained in this embodiment are as follows: the fluidity of the paste is 182 mm; the setting time is 16.5 min; the compressive strength at 1.5 h is 32.6 MPa, the compressive strength at 1 day is 61.2 MPa, the compressive strength at 28 days is 93.1 MPa, and the fracture energy is 99.3 N / m.
[0038] Example 4
[0039] A high-toughness magnesium phosphate cementitious material, the raw material mass ratio is as follows: ammonium dihydrogen phosphate: 100 parts, calcined magnesium oxide: 225 parts (75%), waste rubber particles (80 mesh): 45 parts (15%), sulfur concentrate tailings: 30 parts (10%), borax: 7.5 parts, tetrasodium aminodisuccinate: 7.5 parts, water content: 15%, the preparation process is the same as in Example 1.
[0040] The performance test results of the magnesium phosphate cementitious material obtained in this embodiment are as follows: the fluidity of the paste is 176 mm; the setting time is 15.0 min; the compressive strength at 1.5 h is 35.2 MPa, the compressive strength at 1 day is 62.8 MPa, the compressive strength at 28 days is 95.3 MPa, and the fracture energy is 105.2 N / m, which is 60.4% higher than that of Comparative Example 1.
[0041] Example 5
[0042] A high-toughness magnesium phosphate cementitious material, the raw material mass ratio is as follows: 100 parts of dihydrogen phosphate, 195 parts (65%) of calcined magnesium oxide, 60 parts (20%) of waste rubber particles (100 mesh), 45 parts (15%) of sulfur concentrate tailings, 6 parts of borax, 6 parts of tetrasodium aminodisuccinate, and 18% water. The preparation process is the same as in Example 1.
[0043] The performance test results of the magnesium phosphate cementitious material obtained in this embodiment are as follows: the fluidity of the paste is 179 mm; the setting time is 15.5 min; the compressive strength at 1.5 h is 28.5 MPa, the compressive strength at 1 d is 55.4 MPa, the compressive strength at 28 d is 90.6 MPa, and the rupture energy is 112.2 N / m.
[0044] Comparative Example 1
[0045] A magnesium phosphate cementitious material without the addition of rubber particles and sulfur tailings has the following raw material mass ratio: 100 parts of dihydrogen phosphate, 300 parts of calcined magnesium oxide, 10.5 parts of borax, 10.5 parts of tetrasodium aminodisuccinate, and 16% water. The preparation process is the same as in Example 1.
[0046] The performance test results of the magnesium phosphate cementitious material obtained in Comparative Example 1 are as follows: the fluidity of the paste is 182 mm; the setting time is 11.0 min; the compressive strength at 1.5 h is 39.3 MPa, the compressive strength at 1 d is 61.3 MPa, the compressive strength at 28 d is 82.3 MPa, and the fracture energy is 65.6 N / m.
[0047] Comparative Example 2
[0048] A magnesium phosphate cementitious material containing only sulfur tailings and no rubber particles is provided. The raw material mass ratio is as follows: 100 parts of dihydrogen phosphate, 270 parts (90%) of calcined magnesium oxide, 90 parts (30%) of sulfur tailings, 7.5 parts of borax, 7.5 parts of tetrasodium aminodisuccinate, and 14% water. The preparation process is the same as in Example 1.
[0049] The performance test results of the magnesium phosphate cementitious material obtained in Comparative Example 2 are as follows: the fluidity of the paste is 181 mm; the setting time is 15.5 min; the compressive strength at 1.5 h is 34.5 MPa, the compressive strength at 1 day is 58.1 MPa, the compressive strength at 28 days is 76.6 MPa, and the fracture energy is 68.3 N / m.
[0050] Comparative Example 3
[0051] A magnesium phosphate cementitious material containing only rubber particles and no sulfur tailings has the following raw material mass ratio: 100 parts of ammonium dihydrogen phosphate, 255 parts (85%) of calcined magnesium oxide, 45 parts (15%) of waste rubber particles (80 mesh), 9.8 parts of borax, 9.8 parts of tetrasodium iminodisuccinate, and 18% water. The preparation process is the same as in Example 1.
[0052] The performance test results of the magnesium phosphate cementitious material obtained in this embodiment are as follows: the fluidity of the paste is 179 mm; the setting time is 16.5 min; the compressive strength at 1.5 h is 28.8 MPa, the compressive strength at 1 day is 54.8 MPa, the compressive strength at 28 days is 85.4 MPa, and the fracture energy is 103.7 N / m.
[0053] The above results show that, compared with Comparative Examples 1 and 2 (without rubber particles), the fracture energy of the magnesium phosphate cementitious material obtained in this invention is significantly improved. Example 4 shows a 60.4% increase in fracture energy compared to Comparative Example 1, and Example 5 shows a 71.0% increase. The 1.5-hour compressive strength of Example 4 exceeds 35 MPa, the 1-day compressive strength exceeds 62.5 MPa, and the 28-day compressive strength reaches 95.3 MPa. The fluidity of all examples was controlled within the range of 175-185 mm by adjusting the water-cement ratio, and the setting time was greater than 15 min, while the setting time of Comparative Example 1 was only 11 min. For Comparative Example 3, which only added rubber particles, although the fracture energy was high, the compressive strength at each age was relatively low. This is because, without sulfur tailings and with only rubber particles added, the fluidity of the slurry is low. To achieve the fluidity specified in the standard (JC / T 2857-2024), the water-cement ratio needs to be increased, which inevitably reduces the strength of the magnesium phosphate cement.
[0054] Obviously, the above embodiments are merely examples for clear illustration and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations. However, any obvious variations or modifications derived therefrom are still within the scope of protection of this invention.
[0055] Table of raw material ratios and performance test results for each embodiment and comparative example
Claims
1. A high-toughness magnesium phosphate cementitious material, characterized in that, Composed of the following raw materials: calcined magnesium oxide, ammonium dihydrogen phosphate, composite retarder, and solid waste, wherein the solid waste includes waste tire pellets and sulfur concentrate tailings, and the mass fraction range of the calcined magnesium oxide, ammonium dihydrogen phosphate, composite retarder, and solid waste is as follows: Ammonium dihydrogen phosphate: 100 parts; Reburned magnesium oxide: 195-255 parts; Solid waste: 45-105 portions; Composite retarder: 12-21 parts; Water consumption: 14%-18% of the total solid mass.
2. The high-toughness magnesium phosphate cementitious material according to claim 1, characterized in that... The preparation method is carried out according to the following steps: Step 1: Preparation of waste tire rubber particles. Commercially available crushed waste tire particles are soaked in a 5-10% NaOH aqueous solution for 2-8 hours, filtered, washed with deionized water until neutral, and dried at 80°C to constant weight. Then, the dried rubber particles are added to a mixing pot, and 2-3% silane coupling agent ethanol-water solution is sprayed into the mixing pot while stirring for 30 minutes. Finally, the mixture is dried to obtain modified rubber particles. Step 2: First, add water to the mixing pot according to the standard consistency water volume. Then, quickly add the mixture of calcined magnesium oxide, ammonium dihydrogen phosphate, composite retarder and solid waste into the mixing pot within 5-10 seconds. Stir slowly for 2 minutes, stop for 15 seconds, scrape the slurry from the pot wall into the pot, and then stir quickly for 2 minutes to obtain a high-toughness magnesium phosphate cementitious material.
3. The high-toughness magnesium phosphate cementitious material according to claim 1, characterized in that, The solid waste accounts for 15-35% of the total mass of calcined magnesia and solid waste, of which rubber particles account for 30-60 parts, or 10%-20%; and sulfur concentrate tailings account for 15-45 parts, or 5-15%.
4. The high-toughness magnesium phosphate cementitious material according to claim 1, characterized in that, The composite retarder comprises borax and tetrasodium iminodisuccinate, with a mass ratio of borax to tetrasodium iminodisuccinate of 1:
1. The composite retarder accounts for 4-7% of the total mass of calcined magnesium oxide and solid waste.
5. The high-toughness magnesium phosphate cementitious material according to claim 1, characterized in that, The sulfur concentrate tailings are the residual waste from the flotation of sulfur concentrate (pyrite) to produce sulfur concentrate powder. They are a grayish-green powder that is dried and ground before use, with a specific surface area of 1300-1500 m². 2 / kg.
6. The high-toughness magnesium phosphate cementitious material according to claim 1, characterized in that, The recalcined magnesia is produced by calcining magnesite at a high temperature of 1500-1600℃, and the MgO content in the obtained recalcined magnesia is 85%.
7. The high-toughness magnesium phosphate cementitious material according to claim 1, characterized in that, The recalcined magnesium oxide described in claim 1 has a fineness of 300-400 mesh and a specific surface area of 900-1000 m². 2 / kg.