Water-resistant full-solid-waste phosphogypsum road-building material and preparation method thereof

Abstract

The application discloses an anti-water type full-solid-waste phosphogypsum road building material and a preparation method thereof. A production raw material formula comprises the following components in the following mass ratio: 100 parts of phosphogypsum, 3-18 parts of functional solid waste, 0.06-0.15 parts of a dispersing agent and 0.12-0.28 parts of an adsorbent; the functional solid waste is composed of the following components in the following weight ratio: 78 parts of blast furnace ore powder, 0.1-12 parts of waste concrete powder, 3-8 parts of alkali residue powder and 5-16 parts of magnesium slag powder; the dispersing agent comprises potassium sodium tartrate; and the adsorbent is composed of polyaluminum sulfate and active aluminum oxide in a mass ratio of 1:0.8-1.3. The application has the following advantages: 1) the water resistance of the phosphogypsum road building material is significantly improved; 2) the phosphogypsum pollutants are solidified and stored, physical solidification and chemical bonding are achieved, and the environmental protection performance is safe and reliable; and 3) carbon emission and material cost are significantly reduced, and the problem of the mutual contradiction between the high phosphogypsum content and the low comprehensive performance-price ratio of the large-mixing-amount phosphogypsum road building material is solved.

Description

TECHNICAL FIELD

[0001] The application relates to a building material production technology, in particular to a phosphogypsum road building material production method. BACKGROUND

[0002] Phosphogypsum is an industrial by-product of the wet-process phosphoric acid leaching process, is acidic, has many internal impurity elements, and has a high difficulty in large-scale disposal, especially the excessive soluble phosphorus and fluorine dissolution concentration limits its large-scale resource utilization, but long-term stacking still causes pollution to the surrounding soil, water quality, and atmosphere. At present, the resource utilization of phosphogypsum is mainly concentrated in the fields of building materials and agricultural materials, but the disposal scale is limited, and the comprehensive utilization rate is not high, and the road field as an application scenario capable of absorbing a large amount of phosphogypsum is concerned.

[0003] Cement is commonly used as the most commonly used cementitious material to prepare road water-stable materials, modified solidified soil and the like, but the cement cementation solidification of phosphogypsum used as road building material has the following practical application problems: first, when the application proportion of phosphogypsum is low, the purpose of large-scale utilization of phosphogypsum cannot be achieved, and the relatively high cement dosage will significantly increase the material cost, and there is a risk of poor long-term volume stability and excessive pollution dissolution concentration; second, when the application proportion of phosphogypsum is high, the strength of the road building material is too low to meet the road requirements and control the pollution dissolution effect. That is, the comprehensive contradiction between high phosphogypsum dosage and good road performance, low material cost, and environmental safety standard seriously hinders the large-scale resource utilization of phosphogypsum in the road field.

[0004] Patent document CN118459164A discloses an anti-water environment-friendly high-dosage phosphogypsum base material and a preparation method and application thereof, the cement content is 10% to 20%, and the unconfined compressive strength of the material after 7d standard curing and then soaking in water for 28d is lower than that after 28d direct standard curing, indicating that the material does not have water resistance. If the reaction system of phosphogypsum can be improved, the pollutants in phosphogypsum can be effectively solidified, stabilized and stored, and the water resistance can be improved, so that the durability of the high-dosage phosphogypsum road building material is more stable and reliable, and the full-solid waste road building not only can reduce the road construction cost, but also can promote environmental protection, and has great economic benefits and ecological construction effect. Therefore, it is of urgent practical significance to develop an anti-water high-dosage phosphogypsum base full-solid waste road building material to solve the above problems. SUMMARY

[0005] In order to solve the contradiction between high phosphogypsum dosage and low comprehensive performance price of the cement-bonded phosphogypsum for preparing road materials, and the poor water resistance of the road material with large amount of phosphogypsum after long-term soaking, and optimize the volume stability in the later period to realize the effective solidification, stabilization and storage of phosphogypsum pollutants, and achieve the purpose of large-scale resource utilization of phosphogypsum, the application provides an anti-water type full-solid waste phosphogypsum road material and a preparation method thereof.

[0006] The technical scheme adopted by the application is: a preparation method of the anti-water type full-solid waste phosphogypsum road material, characterized by that: the production raw material formula comprises the following components in the mass fraction: 100 parts of phosphogypsum, 3-18 parts of functional solid waste, 0.06-0.15 parts of dispersant, and 0.12-0.28 parts of adsorbent; the functional solid waste is composed of the following components in the weight fraction: 78 parts of blast furnace slag, 0.1-12 parts of waste concrete powder, 3-8 parts of alkali slag powder, and 5-16 parts of magnesium slag powder; the dispersant comprises potassium sodium tartrate; and the adsorbent is composed of polyaluminum sulfate and active alumina in a mass ratio of 1:0.8-1.3.

[0007] Part of the component description:

[0008] The "blast furnace slag" in the application refers to a solid waste powder obtained by grinding a molten material with silicate and silico-aluminate as main components after quenching and granulating during blast furnace smelting of pig iron.

[0009] The "waste concrete powder" in the application refers to a solid waste powder formed by crushing and grinding of waste concrete with original C30 and above strength grade.

[0010] The "alkali slag powder" in the application refers to a solid waste powder obtained by grinding of alkali slag with main components of calcium carbonate and calcium sulfate discharged during the ammonia-soda process.

[0011] The "magnesium slag powder" in the application refers to a solid waste powder obtained by grinding of magnesium slag with silicate minerals as main components during industrial smelting of metallic magnesium.

[0012] The poor water resistance of the large-dosage phosphogypsum-based road material leads to unqualified strength and environmental protection, and the micro mechanism mainly has three points: 1, the fundamental reason is that the phosphogypsum is slightly soluble in water, and the surface crystals are easy to dissolve to form Ca 2+ and SO4 2-The ions enter the water solution. 2, The internal reason is that the phosphogypsum crystal is in irregular shape such as needle shape and plate shape, resulting in that there are more pores between the phosphogypsum particles, and the irregularly shaped crystals are connected, which aggravates the aggregation between the phosphogypsum particles, and the internal pores of the particles are covered with more free water molecules. When the environmental humidity changes, the water in the phosphogypsum will evaporate or migrate, at this time, the ions dissolved in the water may not recrystallize in situ, but recrystallize in the pores or on the surface of the material. The growth of new crystals will produce a huge crystallization pressure, which will expand the original crystal structure from the inside, resulting in microcracks, surface powdering, flaky and peeling of the material. And each time the water changes, such as dry-wet cycle, will aggravate this damage, and the structure will be completely destroyed. 3, The external reason is that the phosphogypsum contains impurities such as phosphorus and fluorine adsorbed and wrapped on the surface of the particles, so that the water film attached to the surface of the phosphogypsum particles is acidic. Under acidic conditions, the solubility of calcium sulfate dihydrate is significantly improved, thereby accelerating the above dissolution-recrystallization process, greatly increasing the dissolution rate of gypsum, and doubling the speed of the damage process.

[0013] As a further improvement of the application, the dispersant is composed of potassium sodium tartrate and polycarboxylic acid water reducing agent in a mass ratio of 1:1.5-2.7.

[0014] The application can be implemented according to the following steps:

[0015] S1, according to the production raw material formula, each raw material is taken in an amount, and the total amount of water is calculated;

[0016] S2, the dispersant is dissolved to obtain a dispersant solution by adding water to the total amount of water at 20-30%, and then the dispersant solution is uniformly added to the phosphogypsum at a stirring speed of 250-350 r / min for 6-8 min, and then sealed at room temperature for 6-8 h to obtain pretreated phosphogypsum;

[0017] S3, the adsorbent is fully dispersed by adding water to the total amount of water at 20-30%, and then immediately added to the pretreated phosphogypsum at a stirring speed of 250-350 r / min for 3-5 min, and then sealed at room temperature for 12-18 h to obtain modified phosphogypsum;

[0018] S4, the functional solid waste is mixed and ground for 2-3 min to obtain a solid waste mixture;

[0019] S5, the modified phosphogypsum and the solid waste mixture are mixed, and the remaining amount of water is added to the total amount of water, and stirred at a stirring speed of 1200-1300 r / min for 5-10 min to obtain a wet mixture;

[0020] S6, the wet mixture is pressed into shape according to the needs, and then cured at 15-30 DEG C for at least 5 days, to obtain the water-resistant full solid waste phosphogypsum road building material.

[0021] As understood by those skilled in the art, the "total water" in the above scheme refers to the total water excluding the moisture contained in the wet phosphogypsum, which is calculated according to the compaction test method of the standard JTG 3441-2024 of the "Highway Engineering Inorganic Binder Stabilized Material Test Regulations". If the regulations are revised, the corresponding regulations after revision are naturally followed.

[0022] As a further improvement of the application, the phosphogypsum satisfies: calcium sulfate dihydrate (CaSO4·2H2O) content ≥ 90%, aging time greater than 6 months, particle size ≤ 1.18 mm, attached water content ≤ 10%, pH ≥ 4.5.

[0023] It should be noted that the blast furnace powder used in the application should satisfy: specific surface area 500-600 m² / kg, 28d activity index ≥ 105%. The waste concrete powder should satisfy: Na2O content 5%-8%, specific surface area 800-1000 m² / kg. The alkali residue powder should satisfy: easily soluble salt content ≤ 5%, concentration degree of particle size between 0.005-0.05 mm ≥ 90%. The magnesium slag powder should satisfy: specific surface area 600-800 m² / kg, MgO content 3%-7%, CaO content ≥ 65%.

[0024] As a further improvement of the application, the salt base degree of the polyaluminum sulfate is 55%-60%; the particle size of the active alumina is 1-300 nm, and the Al2O3 content is ≥ 95%; the polycarboxylic acid water reducing agent is a hyperbranched polycarboxylic acid water reducing agent, with water reducing rate ≥ 38% and adsorption capacity ≥ 8 mg / g.

[0025] The application further discloses a water-resistant full solid waste phosphogypsum road building material, which is prepared by the preparation method of the water-resistant full solid waste phosphogypsum road building material.

[0026] The application has the following beneficial effects:

[0027] (1) The application disperses the phosphogypsum particles and releases free water and soluble pollutants such as phosphorus and fluorine to stabilize them through the pretreatment process, and then combines the synergistic effect of each component of the functional solid waste to form the water-resistant full solid waste phosphogypsum road building material, so that the road building material continuously and stably increases in compressive strength during long-term soaking, and does not decrease due to the extension of soaking time, which embodies excellent water resistance.

[0028] (2) This invention utilizes an adsorbent to adsorb, complex, and precipitate soluble phosphorus and fluorine in phosphogypsum, thereby achieving its stabilization treatment. Combined with the cementing and solidification effect of hydration products, it further achieves the solidification and sealing of phosphogypsum pollutants, achieving the dual effects of physical solidification and chemical bonding. The environmental performance is safe and reliable.

[0029] (3) This invention uses solid waste materials to formulate road construction materials with a large amount of phosphogypsum, which significantly reduces carbon emissions and material costs compared with cement-stabilized crushed stone materials. It solves the engineering application problem and environmental protection problem of the contradiction between the high amount of phosphogypsum and the low overall cost performance of road construction materials with a large amount of phosphogypsum, and achieves the goal of large-scale resource utilization of phosphogypsum. It has good environmental and economic benefits. Detailed Implementation

[0030] The present invention will be further described below with reference to embodiments.

[0031] All materials used in the following examples and comparative examples were from the same batch and met the following parameters:

[0032] Phosphogypsum: Calcium sulfate dihydrate (CaSO4·2H2O) content 96.4%, aging time 10 months, particle size ≤1.03mm, attached water content 5.3%, pH 4.9.

[0033] Blast furnace ore powder: specific surface area 568m² / kg, 28d activity index 107%.

[0034] Waste concrete powder: solid waste powder formed by crushing and grinding waste concrete of original C30 strength grade, with Na2O content of 6.9% and specific surface area of ​​935m² / kg.

[0035] Alkali residue powder: soluble salt content 3.4%, particle size concentration between 0.005 and 0.05 mm is 96.9%.

[0036] Magnesium slag powder: specific surface area 706 m² / kg, MgO content 5.7%, CaO content 78.1%.

[0037] Aluminum polysulfate: basicity 59.1%;

[0038] Activated alumina: particle size D50=43nm, Al2O3 content ≥98.2%;

[0039] The polycarboxylate superplasticizer is a hyperbranched polycarboxylate superplasticizer with a water reduction rate of 41.5% and an adsorption capacity of 9.6 mg / g.

[0040] Example 1:

[0041] Prepare road construction materials according to the following steps:

[0042] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste, 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the functional solid waste is composed of the following components in the following weight proportions: 78 parts of blast furnace ore powder, 12 parts of waste concrete powder, 8 parts of alkali slag powder and 16 parts of magnesium slag powder; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0043] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0044] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0045] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0046] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0047] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain water-resistant solid waste phosphogypsum road construction material.

[0048] Example 2:

[0049] Prepare road construction materials according to the following steps:

[0050] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 4 parts of functional solid waste, 0.06 parts of dispersant, and 0.12 parts of adsorbent; wherein the functional solid waste is composed of the following components in the following weight proportions: 78 parts of blast furnace ore powder, 2 parts of waste concrete powder, 3 parts of alkali slag powder and 7 parts of magnesium slag powder; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:2.5; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.2.

[0051] (2) Dissolve the dispersant in water at 20% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 250 r / min for 7 min. Then, seal the material at room temperature for 6 h to obtain pretreated phosphogypsum.

[0052] (3) Add water at 20% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 250 r / min for 4 min. Then seal and let it sit at room temperature for 15 h to obtain modified phosphogypsum.

[0053] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0054] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1250 r / min for 8 min to obtain a wet mixture;

[0055] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 58 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 22℃ and a relative humidity of 95% for 6 days to obtain water-resistant solid waste phosphogypsum road construction material.

[0056] Example 3:

[0057] Prepare road construction materials according to the following steps:

[0058] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 10 parts of functional solid waste, 0.12 parts of dispersant, and 0.13 parts of adsorbent; wherein the functional solid waste is composed of the following components in the following weight proportions: 78 parts of blast furnace ore powder, 15 parts of waste concrete powder, 10 parts of alkali slag powder and 18 parts of magnesium slag powder; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:1.8; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:0.8.

[0059] (2) Dissolve the dispersant in water at 30% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 200 r / min for 5 min. Then, seal and let it sit at room temperature for 6 h to obtain pretreated phosphogypsum.

[0060] (3) Add water at 30% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 200 r / min for 3 min. Then seal and let it sit at room temperature for 14 h to obtain modified phosphogypsum.

[0061] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0062] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1200 r / min for 8 min to obtain a wet mixture;

[0063] (6) The wet mixture is loaded into a mold with a diameter of 50 mm and pressed into a cylindrical test block of ϕ50 mm×50 mm under a pressure of 62 MPa. The test block is then placed in a standard curing room with a temperature of 18℃ and a relative humidity of 95% for 6 days to obtain water-resistant solid waste phosphogypsum road construction material.

[0064] Comparative Example 1:

[0065] This comparative example is a control experiment of Example 1, using the commonly used method of preparing road construction materials with phosphogypsum and cement, as follows:

[0066] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum and 15 parts of cement.

[0067] (2) The phosphogypsum, cement and water are mixed and stirred at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0068] (3) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0069] Comparative Example 2:

[0070] This comparative example is a control experiment of Example 1, carried out according to the same steps and conditions as Example 1, except that: no material curing treatment was performed in steps (2) and (3), and the specific scheme is as follows:

[0071] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste, 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the functional solid waste is composed of the following components in the following weight proportions: 78 parts of blast furnace ore powder, 12 parts of waste concrete powder, 8 parts of alkali slag powder and 16 parts of magnesium slag powder; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0072] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution, and then uniformly add the dispersant solution to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min to obtain pretreated phosphogypsum.

[0073] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min to obtain modified phosphogypsum.

[0074] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0075] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0076] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0077] Comparative Example 3:

[0078] This comparative example serves as a control experiment for Example 1, conducted according to the same steps and conditions as Example 1, except that only polycarboxylate superplasticizer is used as the dispersant, without potassium sodium tartrate. The specific scheme is as follows:

[0079] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste, 0.06 parts of dispersant (polycarboxylate superplasticizer) (minus sodium potassium tartrate), and 0.20 parts of adsorbent; wherein the functional solid waste is composed of the following components in the following weight proportions: 78 parts of blast furnace ore powder, 12 parts of waste concrete powder, 8 parts of alkali slag powder and 16 parts of magnesium slag powder; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0080] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0081] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0082] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0083] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0084] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0085] Comparative Example 4:

[0086] This comparative example is a control experiment of Example 1, conducted according to the same steps and conditions as Example 1, except that the waste concrete powder was replaced with cement of equal mass and equivalent specific surface area. The specific scheme is as follows:

[0087] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste, 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the functional solid waste is composed of the following components in the following weight proportions: 78 parts of blast furnace ore powder, 12 parts of cement (specific surface area of ​​941 m² / kg), 8 parts of alkali slag powder and 16 parts of magnesium slag powder; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0088] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0089] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0090] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0091] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0092] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0093] Comparative Example 5:

[0094] This comparative example is a control experiment of Example 1, conducted according to the same steps and conditions as Example 1, with the difference that all functional solid waste is blast furnace ore powder, and the total amount of functional solid waste used remains unchanged. The specific scheme is as follows:

[0095] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste (blast furnace ore powder), 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0096] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0097] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0098] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0099] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0100] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0101] Comparative Example 6:

[0102] This comparative example is a control experiment of Example 1, conducted according to the same steps and conditions as Example 1, with the difference that all functional solid waste is waste concrete powder, and the total amount of functional solid waste used remains unchanged. The specific scheme is as follows:

[0103] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste (waste concrete powder), 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate superplasticizer in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0104] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0105] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0106] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0107] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0108] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0109] Comparative Example 7:

[0110] This comparative example is a control experiment of Example 1, conducted according to the same steps and conditions as Example 1, with the difference that all functional solid waste is alkaline slag powder, and the total amount of functional solid waste used remains unchanged. The specific scheme is as follows:

[0111] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste (alkali slag powder), 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate water-reducing agent in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0112] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0113] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0114] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0115] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0116] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0117] Comparative Example 8:

[0118] This comparative example is a control experiment of Example 1, conducted according to the same steps and conditions as Example 1, with the difference that all functional solid waste is magnesium slag powder, and the total amount of functional solid waste used remains unchanged. The specific scheme is as follows:

[0119] (1) Take the raw materials according to the following production raw material formula and calculate the total amount of water to be added according to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024: 100 parts of phosphogypsum, 15 parts of functional solid waste (magnesium slag powder), 0.09 parts of dispersant, and 0.20 parts of adsorbent; wherein the dispersant is composed of potassium sodium tartrate and polycarboxylate water-reducing agent in a mass ratio of 1:2; wherein the adsorbent is composed of polyaluminum sulfate and activated alumina in a mass ratio of 1:1.

[0120] (2) Dissolve the dispersant in water at 25% of the total amount of water to obtain a dispersant solution. Then, add the dispersant solution evenly to the phosphogypsum and stir at a stirring rate of 300 r / min for 8 min. Then, seal and let it sit at room temperature for 8 h to obtain pretreated phosphogypsum.

[0121] (3) Add water at 25% of the total amount of water to fully disperse the adsorbent, and then immediately add it to the pretreated phosphogypsum and stir at a stirring rate of 300 r / min for 5 min. Then seal and let it sit at room temperature for 18 h to obtain modified phosphogypsum.

[0122] (4) Grind the functional solid waste for 3 minutes to obtain a solid waste mixture;

[0123] (5) After mixing the modified phosphogypsum with the solid waste mixture, add the remaining water equal to the total amount of water added, and stir at a stirring rate of 1300 r / min for 10 min to obtain a wet mixture;

[0124] (6) The wet mixture is loaded into a mold with a diameter of 50 mm, and the pressure is controlled at 60 MPa to press it into a cylindrical test block of ϕ50 mm × 50 mm. Then, it is placed in a standard curing room with a temperature of 20 °C and a relative humidity of 96% for 6 days to obtain phosphogypsum road construction material.

[0125] Comparative experiment on the water resistance of phosphogypsum road construction materials:

[0126] According to the "Test Procedure for Inorganic Binder Stabilized Materials for Highway Engineering" JTG 3441-2024, the standard unconfined compressive strength and the unconfined compressive strength after soaking in water of the phosphogypsum-based road construction materials in the examples and comparative examples were determined to reflect their water resistance performance. The test results are shown in Table 1.

[0127] Table 1. Comparison of Water Resistance Properties of Phosphogypsum Road Building Materials (Characterized by Representative Values ​​of Unconfined Compressive Strength)

[0128] Standard curing 14d (MPa) Standard curing 6d + water curing 8d (MPa) Standard curing 28d (MPa) Standard curing 6d + water curing 22d (MPa) Example 1 6.36 8.56 11.32 11.81 Example 2 4.93 6.60 8.35 8.83 Example 3 6.02 7.83 9.87 10.32 Comparative Example 1 (Prior Art) 3.52 2.87 4.98 3.36 Comparative Example 2 (No Curing) 5.79 6.27 8.32 8.02 Comparative Example 3 (No Potassium Sodium Tartrate) 6.39 6.32 11.27 10.55 Comparative Example 4 (Cement Replaced by Concrete Powder) 3.12 2.68 4.32 3.27 Comparative Example 5 (Single Blast Furnace Slag) 1.19 0 (Disintegrated) 1.61 0 (Disintegrated) Comparative Example 6 (Single Waste Concrete Powder) 1.04 0 (Disintegrated) 1.56 0 (Disintegrated) Comparative Example 7 (Single Alkaline Slag) 0.98 0 (Disintegrated) 1.07 0 (Disintegrated) Comparative Example 8 (Single Magnesium Slag) 0.85 0 (Disintegrated) 1.02 0 (Disintegrated)

[0129] As can be seen from the test results of Examples 1 to 3 in Table 1, the strength of the water-resistant phosphogypsum-based solid waste road construction material samples prepared by the method of the present invention after soaking in water is higher than that of the samples of the same age that have not been soaked in water. Moreover, the strength of the samples still increases slightly with the extension of the soaking time, showing excellent water resistance.

[0130] As can be seen from the comparison of the test results of Example 1 and Comparative Example 2 in Table 1, although the strength of the specimen in Comparative Example 2 did not decrease significantly after short-term immersion in water, the strength began to decrease after the immersion time was extended, which proves that the immersion method adopted in this invention can improve the water resistance of phosphogypsum road construction materials to a certain extent.

[0131] As can be seen from the comparison of the test results of Example 1 and Comparative Example 3 in Table 1, if potassium sodium tartrate is not used in the curing process, the short-term and long-term water resistance of the specimens are affected to a certain extent and show a downward trend. This indicates that in this invention, potassium sodium tartrate has a positive effect on the water resistance of phosphogypsum road construction materials. The inventors believe that the reason is that potassium sodium tartrate can selectively form directional adsorption on specific crystal faces of phosphogypsum crystals, causing the phosphogypsum particles to separate due to the electrostatic repulsion of potassium / sodium carboxylate groups (-COO-) and the steric hindrance effect of hyperbranched polycarboxylate superplasticizer, releasing the encapsulated free water, and achieving full contact between functional solid waste and phosphogypsum particles. Hydration forms needle-like AFt that fills the gaps between phosphogypsum particles, and C(-A)-SH gel encapsulates and cements phosphogypsum particles and ettringite crystals to form a dense structure, thereby reducing the porosity caused by subsequent water evaporation.

[0132] As can be seen from the comparison of the test results of Example 1 and Comparative Example 4 in Table 1, when the waste concrete powder in Example 1 was replaced with cement, the long-term standard curing strength and short-term and long-term water resistance of the specimens both decreased significantly, indicating that the waste concrete powder used in this invention cannot be replaced with cement.

[0133] As can be seen from the comparison of Examples 1, 5, 6, 7 and 8 in Table 1, when blast furnace ore powder, waste concrete powder, alkali slag powder or magnesium slag powder are added individually as functional solid waste, under the premise of the same usage, the compressive strength of the phosphogypsum road construction material is significantly reduced compared with Example 1. Moreover, the unconfined compressive strength in both short-term and long-term water immersion test results is significantly lower than that of the un-water-immersed sample, leading to collapse. However, the composite functional solid waste composed of blast furnace ore powder, waste concrete powder, alkali slag powder and magnesium slag powder in Example 1 shows a significant increase in the compressive strength of the sample, and the strength after water immersion is higher than that of the un-water-immersed sample of the same age. This indicates that blast furnace ore powder, waste concrete powder, alkali slag powder and magnesium slag powder have a significant synergistic effect in improving the water resistance of phosphogypsum road construction material in this invention. The inventors believe that the reason is that when blast furnace ore powder, waste concrete powder, alkali slag powder and magnesium slag powder are used in combination, they can play a synergistic regulatory role on the hydration reaction process, so that the entire phosphogypsum material mixing system is transformed from an air-hardening material system to a hydraulic material system, which changes the degree to which each component in the system participates in the hydration reaction, thereby achieving a fundamental improvement in water resistance.

Claims

1. A water-resistant full-solid-waste phosphogypsum road-building material, characterized in that: The application relates to a water-resistant full-solid waste phosphogypsum road material, which comprises the following components in the following mass ratio: 100 parts of phosphogypsum, 3 to 18 parts of functional solid waste, 0.06 to 0.15 parts of dispersant and 0.12 to 0.28 parts of adsorbent; the functional solid waste is composed of the following components in the following weight ratio: 78 parts of blast furnace ore powder, 0.1 to 12 parts of waste concrete powder, 3 to 8 parts of alkali residue powder and 5 to 16 parts of magnesium slag powder; the adsorbent is composed of polyaluminum sulfate and active aluminum oxide in a mass ratio of 1:0.8 to 1.3; and the dispersant is composed of potassium sodium tartrate and polycarboxylic acid water reducing agent in a mass ratio of 1:1.5 to 2.

7.

2. The method for preparing the water-resistant full-solid waste phosphogypsum road-building material according to claim 1, characterized in that, The application further relates to a preparation method of the water-resistant full-solid waste phosphogypsum road material. S1, obtaining each raw material according to the production raw material formula amount and calculating the total water amount; S2, dissolving the dispersant to obtain a dispersant solution by adding water in an amount of 20 to 30% of the total water amount, then uniformly dropping the dispersant solution into the phosphogypsum and stirring at a stirring speed of 250 to 350 r / min for 6 to 8 min, and then sealing and aging at room temperature for 6 to 8 h to obtain pretreated phosphogypsum; S3, dispersing the adsorbent by adding water in an amount of 20 to 30% of the total water amount, then immediately adding the adsorbent into the pretreated phosphogypsum and stirring at a stirring speed of 250 to 350 r / min for 3 to 5 min, and then sealing and aging at room temperature for 12 to 18 h to obtain modified phosphogypsum; S4, mixing and grinding the functional solid waste for 2 to 3 min to obtain a solid waste mixture; S5, mixing the modified phosphogypsum and the solid waste mixture, then adding the remaining water amount of the total water amount, and stirring at a stirring speed of 1200 to 1300 r / min for 5 to 10 min to obtain a wet mixture; S6, curing the wet mixture at 15 to 30 DEG C for at least 5 d after forming the wet mixture according to the process requirement to obtain the water-resistant full-solid waste phosphogypsum road material.

3. The method for preparing water-resistant full-solid waste phosphogypsum road-building material according to claim 2, characterized in that: The phosphogypsum satisfies the following conditions: the content of calcium sulfate dihydrate is greater than or equal to 90%, the aging time is greater than 6 months, the particle size is less than or equal to 1.18 mm, the attached water content is less than or equal to 10%, and the pH is greater than or equal to 4.

5.

4. The method for preparing water-resistant full-solid waste phosphogypsum road-building material according to claim 2, characterized in that: The blast furnace ore powder satisfies the following conditions: the specific surface area is 500 to 600 m2 / kg, and the 28d activity index is greater than or equal to 105%.

5. The method for preparing water-resistant full-solid waste phosphogypsum road-building material according to claim 2, characterized in that: The waste concrete powder satisfies the following conditions: the Na2O content is 5% to 8%, and the specific surface area is 800 to 1000 m2 / kg.

6. The method for preparing water-resistant full-solid waste phosphogypsum road-building material according to claim 2, characterized in that: The alkali residue powder satisfies the following conditions: the content of easily soluble salt is less than or equal to 5%, and the concentration of the particle size of 0.005 to 0.05 mm is greater than or equal to 90%.

7. The method for preparing water-resistant full-solid waste phosphogypsum road-building material according to claim 2, characterized in that: The magnesium slag powder satisfies the following conditions: the specific surface area is 600 to 800 m2 / kg, the MgO content is 3% to 7%, and the CaO content is greater than or equal to 65%.

8. The method for preparing water-resistant full-solid waste phosphogypsum road-building material according to claim 2, characterized in that: The polyaluminum sulfate has a basicity of 55% to 60%; the active aluminum oxide has a particle size of 1 to 300 nm and an Al2O3 content greater than or equal to 95%; and the polycarboxylic acid water reducing agent is a hyperbranched polycarboxylic acid water reducing agent, has a water reducing rate greater than or equal to 38%, and has an adsorption capacity greater than or equal to 8 mg / g.

9. The water-resistant full-solid waste phosphogypsum road material prepared by the preparation method of the water-resistant full-solid waste phosphogypsum road material according to any one of claims 2 to 8.