Magnesium phosphate-based quick-hardening repairing material and use method thereof

Abstract

The invention belongs to the field of building materials, and particularly relates to a magnesium phosphate-based quick-hardening repairing material and a use method thereof. The magnesium phosphate-based rapid hardening repairing material provided by the invention comprises the following components: phosphate, magnesium oxide, steel slag, mineral slag, a retarder and an alkaline activator, the mass ratio of the phosphate to the magnesium oxide to the steel slag to the mineral slag to the retarder is 24: (43-72): (3-15): (3-15): (2-5); the alkaline activator is sodium silicate or a mixture of sodium silicate and sodium hydroxide; the molar ratio of the silicon content in terms of SiO2 to the sodium content in terms of Na2O in the alkaline activator is less than or equal to 1.5: 1; the use amount of the alkaline activator is 2-10wt% of the total mass of the steel slag and the mineral slag. The magnesium phosphate-based quick-hardening repairing material provided by the invention is high in solid waste mixing amount, and has relatively high strength and water resistance after construction is completed.

Description

Technical Field

[0001] This invention belongs to the field of building materials, and in particular relates to a magnesium phosphate-based fast-hardening repair material and its application method. Background Technology

[0002] Concrete structures such as roads, bridges, and tunnels commonly face early damage and functional degradation under the combined effects of extreme weather events, geological disasters (such as freeze-thaw cycles and landslides), and overloaded operation. Therefore, developing high-performance, fast-setting concrete repair materials has become a key issue in ensuring the durability of infrastructure. Ideal fast-setting repair materials must meet multiple performance requirements: in terms of workability, they must have controllable setting time and good flowability; in terms of mechanical properties, they should achieve rapid early strength development and long-term strength stability.

[0003] Magnesium phosphate-based materials are currently common quick-setting repair materials for concrete, but traditional magnesium phosphate-based materials suffer from poor water resistance. Furthermore, to reduce the production cost of quick-setting concrete repair materials, some solid waste materials such as steel slag and mineral slag are often added to their raw materials. However, due to the low activity of these solid waste materials, their dosage is usually low to avoid adversely affecting the performance of the quick-setting concrete repair materials. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a magnesium phosphate-based rapid-hardening repair material and its application method. The magnesium phosphate-based rapid-hardening repair material provided by the present invention has a high solid waste content and exhibits high strength and water resistance after construction.

[0005] This invention provides a magnesium phosphate-based rapid-hardening repair material, comprising: phosphate, magnesium oxide, steel slag, blast furnace slag, retarder, and alkaline activator; the mass ratio of the phosphate, magnesium oxide, steel slag, blast furnace slag, and retarder is 24:(43~72):(3~15):(3~15):(2~5); the alkaline activator is sodium silicate, or a mixture of sodium silicate and sodium hydroxide; the molar ratio of silicon content (SiO2) to sodium content (Na2O) in the alkaline activator is ≤1.5:1; the amount of the alkaline activator is 2~10 wt% of the total mass of steel slag and blast furnace slag.

[0006] Preferably, the phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate.

[0007] Preferably, the phosphate has a particle size of 0.6~1.2 mm.

[0008] Preferably, the magnesium oxide is calcined magnesium oxide.

[0009] Preferably, the steel slag has a D 50Particle size is 15~20μm, specific surface area is 300~400m² 2 / kg.

[0010] Preferably, the slag has a D 50 Particle size is 10~15μm, specific surface area is 400~500m² 2 / kg.

[0011] Preferably, the retarder is borax.

[0012] Preferably, the molar ratio of silicon content (calculated as SiO2) to sodium content (calculated as Na2O) in the alkaline activator is 1.3:1.

[0013] This invention provides a method for using the magnesium phosphate-based fast-hardening repair material described above, comprising the following steps:

[0014] The magnesium phosphate-based fast-hardening repair material is mixed with water, and then applied and cured.

[0015] Preferably, the mass ratio of the magnesium phosphate-based fast-hardening repair material to water is 1:(0.1~0.2).

[0016] Compared with existing technologies, this invention provides a magnesium phosphate-based rapid-hardening repair material and its application method. The magnesium phosphate-based rapid-hardening repair material provided by this invention comprises: phosphate, magnesium oxide, steel slag, blast furnace slag, retarder, and alkaline activator; the mass ratio of the phosphate, magnesium oxide, steel slag, blast furnace slag, and retarder is 24:(43~72):(3~15):(3~15):(2~5); the alkaline activator is sodium silicate, or a mixture of sodium silicate and sodium hydroxide; the molar ratio of silicon content (SiO2) to sodium content (Na2O) in the alkaline activator is ≤1.5:1; the amount of the alkaline activator is 2~10 wt% of the total mass of steel slag and blast furnace slag. This invention utilizes steel slag and blast furnace slag activated by a specific alkaline activator to replace part of the magnesium oxide in the magnesium phosphate cement-based material, thereby maintaining the rapid-hardening characteristics of the magnesium phosphate cement-based material while improving the material's strength and water resistance. The magnesium phosphate-based rapid-hardening repair material provided by this invention has a high solid waste content and exhibits high strength and water resistance after construction. It solves the contradiction of "high content and low strength" in traditional rapid-hardening repair materials and provides a green and low-carbon solution for the sustainable development of infrastructure repair materials. Detailed Implementation

[0017] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] This invention provides a magnesium phosphate-based rapid-hardening repair material, the components of which include: phosphate, magnesium oxide, steel slag, mineral slag, retarder and alkaline activator.

[0019] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the phosphate is preferably potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate; the particle size of the phosphate is preferably 0.6~1.2 mm, specifically 0.6 mm, 0.65 mm, 0.7 mm, 0.75 mm, 0.8 mm, 0.85 mm, 0.9 mm, 0.95 mm, 1 mm, 1.05 mm, 1.1 mm, 1.15 mm, or 1.2 mm. In this invention, a suitable phosphate particle size can adjust its reaction rate with magnesium oxide, allowing it to react gradually with magnesium oxide.

[0020] In the magnesium phosphate-based rapid-hardening repair material provided by the present invention, the particle size of the magnesium oxide is preferably 20~40μm, specifically 20μm, 21μm, 22μm, 23μm, 24μm, 25μm, 26μm, 27μm, 28μm, 29μm, 30μm, 31μm, 32μm, 33μm, 34μm, 35μm, 36μm, 37μm, 38μm, 39μm or 40μm.

[0021] In the magnesium phosphate-based fast-hardening repair material provided by the present invention, the magnesium oxide is preferably calcined magnesium oxide, which is produced by calcining magnesite; the calcination temperature for preparing the calcined magnesium oxide is preferably 1050~1100℃, and the calcination time is preferably 7~8h.

[0022] In the magnesium phosphate-based rapid-hardening repair material provided by the present invention, the mass ratio of phosphate to magnesium oxide is 24:(43~72), specifically 24:43, 24:44, 24:45, 24:46, 24:47, 24:48, 24:49, 24:50, 24:51, 24:52, 24:53, 24:54, 24:55, 24:56, 24:57, 24:58, 24:59, 24:60, 24:61, 24:62, 24:63, 24:64, 24:65, 24:66, 24:67, 24:68, 24:69, 24:70, 24:71 or 24:72.

[0023] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the D of the steel slag 50The particle size is preferably 15~20μm, specifically 15μm, 15.5μm, 16μm, 16.5μm, 17μm, 17.5μm, 18μm, 18.5μm, 18.52μm, 19μm, 19.5μm or 20μm; the specific surface area of ​​the steel slag is preferably 300~400m². 2 / kg, specifically 300m 2 / kg, 310m 2 / kg, 320m 2 / kg, 330m 2 / kg, 340m 2 / kg, 350m 2 / kg, 360m 2 / kg, 367.3m 2 / kg, 370m 2 / kg, 380m 2 / kg, 390m 2 / kg or 400m 2 / kg.

[0024] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the steel slag preferably comprises MgO, SiO2, CaO, Al2O3, Fe2O3, P2O5, MnO, and SO3; wherein, the MgO content in the steel slag is preferably 2-8 wt%, specifically 4.24 wt%; the SiO2 content in the steel slag is preferably 5-15 wt%, specifically 11.52 wt%; and the CaO content in the steel slag is preferably 40-50 wt%, specifically 45.55 wt%. The preferred Al2O3 content in the steel slag is 2-6 wt%, specifically 4.03 wt%; the preferred Fe2O3 content is 20-30 wt%, specifically 25.05 wt%; the preferred P2O5 content is 1-5 wt%, specifically 2.21 wt%; the preferred MnO content is 2-8 wt%, specifically 3.93 wt%; and the preferred SO3 content is 0.2-0.8 wt%, specifically 0.4 wt%.

[0025] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the mass ratio of phosphate to steel slag is 24:(3~15), specifically 24:3, 24:3.5, 24:4, 24:4.5, 24:5, 24:5.5, 24:6, 24:6.5, 24:7, 24:7.5, 24:8, 24:8.5, 24:9, 24:9.5, 24:10, 24:10.5, 24:11, 24:11.5, 24:12, 24:12.5, 24:13, 24:13.5, 24:14, 24:14.5 or 24:15.

[0026] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the slag's D 50 The particle size is preferably 10~15μm, specifically 10μm, 10.5μm, 11μm, 11.5μm, 12μm, 12.5μm, 12.61μm, 13μm, 13.5μm, 14μm, 14.5μm or 15μm; the specific surface area of ​​the slag is preferably 400~500m². 2 / kg, specifically 400m 2 / kg, 410m 2 / kg, 420m 2 / kg, 430m 2 / kg, 440m 2 / kg, 445.3m 2 / kg, 450m 2 / kg, 460m 2 / kg, 470m 2 / kg, 480m 2 / kg, 490m 2 / kg or 500m 2 / kg.

[0027] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the slag preferably comprises MgO, SiO2, CaO, Al2O3, Fe2O3, P2O5, MnO, and SO3; wherein, the MgO content in the slag is preferably 4-8 wt%, specifically 6.58 wt%; the SiO2 content in the slag is preferably 20-35 wt%, specifically 28.85 wt%; the CaO content in the slag is preferably 40-50 wt%, specifically 44.54 wt%; the slag The preferred Al2O3 content in the slag is 10-20 wt%, specifically 14.72 wt%; the preferred Fe2O3 content in the slag is 0.5-1 wt%, specifically 0.72 wt%; the preferred P2O5 content in the slag is 0.01-0.05 wt%, specifically 0.02 wt%; the preferred MnO content in the slag is 0.4-0.9 wt%, specifically 0.65 wt%; and the preferred SO3 content in the slag is 1-5 wt%, specifically 2.16 wt%.

[0028] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the mass ratio of phosphate to slag is 24:(3~15), specifically 24:3, 24:3.5, 24:4, 24:4.5, 24:5, 24:5.5, 24:6, 24:6.5, 24:7, 24:7.5, 24:8, 24:8.5, 24:9, 24:9.5, 24:10, 24:10.5, 24:11, 24:11.5, 24:12, 24:12.5, 24:13, 24:13.5, 24:14, 24:14.5 or 24:15.

[0029] In the magnesium phosphate-based fast-setting repair material provided by this invention, the retarder is borax.

[0030] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the mass ratio of phosphate to borax is 24:(2~5), specifically 24:2, 24:2.1, 24:2.2, 24:2.3, 24:2.4, 24:2.5, 24:2.6, 24:2.7, 24:2.8, 24:2.9, 24:3, 24:3.1, 24:3.2, 24:3.3, 24:3.4, 24:3.5, 24:3.6, 24:3.7, 24:3.8, 24:3.9, 24:4, 24:4.1, 24:4.2, 24:4.3, 24:4.4, 24:4.5, 24:4.6, 24:4.7, 24:4.8, 24:4.9, or 24:5.

[0031] In the magnesium phosphate-based rapid-hardening repair material provided by this invention, the alkaline activator is sodium silicate, or a mixture of sodium silicate and sodium hydroxide; the molar ratio of silicon content (SiO2) to sodium content (Na2O) in the alkaline activator is ≤1.5:1, preferably 1.3:1. In other words, the alkaline activator used in this invention is a modulus (SiO2) of... 2 / Na2O (molar ratio) ≤ 1.5, preferably water glass with a modulus of 1.3.

[0032] In the magnesium phosphate-based rapid-hardening repair material provided by the present invention, the amount of alkaline activator is 2 to 10 wt% of the total mass of steel slag and blast furnace slag, specifically 2 wt%, 2.5 wt%, 3 wt%, 3.5 wt%, 4 wt%, 4.5 wt%, 5 wt%, 5.5 wt%, 6 wt%, 6.5 wt%, 7 wt%, 7.5 wt%, 8 wt%, 8.5 wt%, 9 wt%, 9.5 wt%, or 10 wt%.

[0033] This invention also provides a method for using the magnesium phosphate-based fast-hardening repair material described above, comprising the following steps:

[0034] The magnesium phosphate-based fast-hardening repair material is mixed with water, and then applied and cured.

[0035] In the method of use provided by the present invention, the mass ratio of the magnesium phosphate-based fast-hardening repair material to water is preferably 1:(0.1~0.2), specifically 1:0.1, 1:0.11, 1:0.12, 1:0.13, 1:0.14, 1:0.15, 1:0.16, 1:0.17, 1:0.18, 1:0.19 or 1:0.2.

[0036] In the method of use provided by the present invention, the mixing process preferably includes: mixing phosphate, magnesium oxide and retarder to obtain a first mixture; mixing steel slag, blast furnace slag, alkaline activator and water to obtain a second mixture; and mixing the first mixture and the second mixture.

[0037] In the usage method provided by the present invention, the maintenance method includes, but is not limited to, natural maintenance and / or water-based maintenance.

[0038] The technical solution provided by this invention utilizes steel slag activated by a specific alkali activator to replace part of the magnesium oxide in magnesium phosphate cement-based materials. While maintaining the rapid-hardening characteristics of magnesium phosphate cement-based materials, it improves the material's strength and water resistance. The magnesium phosphate-based rapid-hardening repair material provided by this invention has a high solid waste content and exhibits high strength and water resistance after construction, resolving the contradiction of "high content, low strength" in traditional rapid-hardening repair materials. This provides a green and low-carbon solution for the sustainable development of infrastructure repair materials.

[0039] For clarity, the following examples and comparative models will be used to provide a detailed description.

[0040] In the following embodiments and comparative examples of the present invention, the magnesium oxide used has a particle size of 32 μm, is produced by calcining magnesite, the calcination temperature is 1050~1100℃, and the calcination time is 7~8 h; the potassium dihydrogen phosphate used has a particle size of 0.9 mm; the steel slag and ore slag used are waste residues generated during steelmaking at Shanghai Baosteel, wherein the steel slag has a D... 50 The particle size is 18.52 μm, and the specific surface area is 367.3 m². 2 / kg, D of slag 50 The particle size is 12.61 μm and the specific surface area is 445.3 m². 2 / kg, the composition of steel slag and blast furnace slag is shown in Table 1:

[0041] Table 1. Composition of steel slag and mineral slag (unit: wt%)

[0042]

[0043] The alkaline activator used is prepared from sodium silicate and sodium hydroxide. The original modulus of sodium silicate (molar ratio of SiO2 to Na2O) is 2.3, and the modulus of the alkaline activator after adding sodium hydroxide is 1.3.

[0044] Comparative Example 1

[0045] Materials: 72 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, and 4 parts by weight of borax.

[0046] Mixing: Mix magnesium oxide, potassium dihydrogen phosphate and borax evenly, then pour into a mixing tank and mix with water. The amount of water should be 0.16 times the total mass of the solids.

[0047] Comparative Example 2

[0048] Materials: 65 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, 3.5 parts by weight of steel slag, 3.5 parts by weight of blast furnace slag, and 4 parts by weight of borax.

[0049] Mixing: First, mix magnesium oxide, potassium dihydrogen phosphate and borax evenly. Then, add water to steel slag and ore slag and mix evenly. Finally, pour all the above mixture into a mixing tank and mix. The amount of water is 0.16 times the total solid mass.

[0050] Comparative Example 3

[0051] Materials: 58 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, 7 parts by weight of steel slag, 7 parts by weight of blast furnace slag, and 4 parts by weight of borax.

[0052] Mixing: First, mix magnesium oxide, potassium dihydrogen phosphate and borax evenly. Then, add water to steel slag and ore slag and mix evenly. Finally, pour all the above mixture into a mixing tank and mix. The amount of water is 0.16 times the total solid mass.

[0053] Comparative Example 4

[0054] Materials: 51 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, 10.5 parts by weight of steel slag, 10.5 parts by weight of blast furnace slag, and 3.6 parts by weight of borax.

[0055] Mixing: First, mix magnesium oxide, potassium dihydrogen phosphate and borax evenly. Then, add water to steel slag and ore slag and mix evenly. Finally, pour all the above mixture into a mixing tank and mix. The amount of water is 0.16 times the total solid mass.

[0056] Example 1

[0057] Materials: 65 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, 3.5 parts by weight of steel slag, 3.5 parts by weight of blast furnace slag, 4 parts by weight of borax, and 8% by weight of alkaline activator (combined with steel slag and blast furnace slag).

[0058] Mixing: First, mix magnesium oxide, potassium dihydrogen phosphate and borax evenly. Then, add water to steel slag, ore slag and alkaline activator and mix evenly. Finally, pour all the above mixture into a mixing tank and mix. The amount of water is 0.16 times the total solid mass.

[0059] Example 2

[0060] Materials: 58 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, 7 parts by weight of steel slag, 7 parts by weight of blast furnace slag, 4 parts by weight of borax, and 8% by weight of alkaline activator from the combined mass of steel slag and blast furnace slag.

[0061] Mixing: First, mix magnesium oxide, potassium dihydrogen phosphate and borax evenly. Then, add water to steel slag, ore slag and alkaline activator and mix evenly. Finally, pour all the above mixture into a mixing tank and mix. The amount of water is 0.16 times the total solid mass.

[0062] Example 3

[0063] Materials: 51 parts by weight of magnesium oxide, 24 parts by weight of potassium dihydrogen phosphate, 10.5 parts by weight of steel slag, 10.5 parts by weight of blast furnace slag, 4 parts by weight of borax, and 8% by weight of alkaline activator (combined with steel slag and blast furnace slag).

[0064] Mixing: First, mix magnesium oxide, potassium dihydrogen phosphate and borax evenly. Then, add water to steel slag, ore slag and alkaline activator and mix evenly. Finally, pour all the above mixture into a mixing tank and mix. The amount of water is 0.16 times the total solid mass.

[0065] Performance Evaluation

[0066] The samples prepared in Comparative Examples 1-4 and Examples 1-3 were tested for fluidity, setting time, compressive strength, and water resistance. The testing methods are as follows:

[0067] (1) Flowability: Determined according to Chinese national standard GB / T 8077-2012.

[0068] (2) Setting time: determined according to Chinese standard GB / T1346-2011.

[0069] (3) Compressive strength: In accordance with the Chinese standard GB / T 17671-1999, the compressive strength of specimens with dimensions of 40mm×40mm×40mm was tested on a universal testing machine with a loading rate of 2.4kN / s. The compressive strength was measured three times at the specified age and the average value was recorded. The compressive strength was determined at 1d, 7d, 14d, and 28d.

[0070] (4) Water resistance strength: The water resistance performance of the sample is evaluated by the strength retention rate (water resistance coefficient). The higher the strength retention rate, the more outstanding the water resistance performance of the sample. The strength retention rate is calculated as the ratio of the compressive strength of the specimen cured in water to the compressive strength of the specimen cured under natural conditions. The calculation formula is W=Fw / Fn, where Fw is the compressive strength of the specimen under water curing (MPa), Fn is the compressive strength of the specimen under natural curing (MPa), and W is the strength retention rate (%). The surface of the specimen should be kept clean and dry before the test (aging: 1, 3, 7, 14, 28 days).

[0071] The test results are shown in Table 1.

[0072] Table 1. Test results of sample fluidity, setting time, compressive strength, and water resistance.

[0073]

[0074] As can be seen from the data in Table 1, the present invention uses alkaline activated steel slag to replace reburned magnesium oxide, which not only saves costs but also increases the utilization rate of solid waste. Furthermore, it can effectively improve the fluidity, strength, and water resistance of magnesium phosphate cement materials, thereby improving their performance. Moreover, the preparation method is simple, the quality is stable, and the requirements for the external environment are low, making it suitable for large-scale production during construction.

[0075] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A magnesium phosphate-based rapid-hardening repair material, characterized in that, The magnesium phosphate-based rapid-hardening repair material comprises: phosphate, magnesium oxide, steel slag, blast furnace slag, retarder, and alkaline activator; the mass ratio of the phosphate, magnesium oxide, steel slag, blast furnace slag, and retarder is 24:(43~72):(3~15):(3~15):(2~5); the alkaline activator is sodium silicate, or a mixture of sodium silicate and sodium hydroxide; the molar ratio of silicon content (SiO2) to sodium content (Na2O) in the alkaline activator is ≤1.5:1; the amount of the alkaline activator is 2~10 wt% of the total mass of steel slag and blast furnace slag.

2. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The phosphate is potassium dihydrogen phosphate and / or ammonium dihydrogen phosphate.

3. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The phosphate has a particle size of 0.6~1.2 mm.

4. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The magnesium oxide is calcined magnesium oxide.

5. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The steel slag D 50 Particle size is 15~20μm, specific surface area is 300~400m² 2 / kg.

6. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The slag D 50 Particle size is 10~15μm, specific surface area is 400~500m² 2 / kg.

7. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The retarder is borax.

8. The magnesium phosphate-based rapid-hardening repair material according to claim 1, characterized in that, The molar ratio of silicon content (SiO2) to sodium content (Na2O) in the alkaline activator is 1.3:

1.

9. A method of using the magnesium phosphate-based rapid-hardening repair material according to any one of claims 1 to 8, characterized in that, Includes the following steps: The magnesium phosphate-based fast-hardening repair material is mixed with water, and then applied and cured.

10. The method of use according to claim 9, characterized in that, The mass ratio of the magnesium phosphate-based rapid-hardening repair material to water is 1:(0.1~0.2).

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