Modified phosphogypsum-based self-healing concrete and preparation method thereof

Abstract

The invention relates to the technical field of building materials, in particular to modified ardealite-based self-healing concrete and a preparation method thereof. The preparation method comprises the following steps: S1, modifying ardealite with quick lime to obtain modified ardealite; s2, weighing 140-164 parts of modified phosphogypsum, 40-60 parts of cement, 3-8 parts of calcium formate, 15-20 parts of a self-healing agent, 0.1-0.8 part of a water reducing agent, 1-3 parts of a water glass solution and 35-60 parts of water, mixing and stirring, and uniformly mixing to obtain mixed slurry; s3, the mixed slurry is put into a mold for curing, and the modified phosphogypsum-based self-healing concrete is obtained. And the self-healing agent is an acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer. The self-healing agent can reduce drying shrinkage of concrete and reduce the cracking risk, the modified phosphogypsum fills pores and promotes later strength increase, the calcium formate accelerates early strength development, and the concrete has excellent mechanical properties at different ages under the combined action of the three.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly relates to a modified phosphogypsum-based self-healing concrete and a preparation method thereof. Background Art

[0002] Phosphogypsum is a solid waste formed during the production of phosphoric acid by the wet process. Its main component is calcium sulfate dihydrate, and it contains trace amounts of phosphorus, fluorine, organic components, oxide impurities, heavy metal elements, and radioactive substances, etc. With the increasing stock of phosphogypsum year by year, a large amount of phosphogypsum cannot be treated in time, which not only occupies land resources, but also causes serious damage to the ecological environment and restricts the development of the phosphorus chemical industry. Realizing the resource utilization of phosphogypsum is an urgent practical problem that needs to be solved at present. Using phosphogypsum as a means to save energy, maintain the ecological environment, and promote the sustainable development of the construction industry and the phosphorus chemical industry has become the focus of global attention.

[0003] At present, in the field of building materials, there has been a technology of using phosphogypsum as a raw material to prepare concrete. For example, a highly consumptive phosphogypsum-based all-solid waste permeable concrete disclosed in Chinese Patent CN116751022A generally has problems such as insufficient early strength, which may lead to delays in the construction progress, poor structural stability, and even potential safety problems. Moreover, it also lacks self-healing ability, and cracks occur after long-term use, resulting in a decline in the durability of the material. Summary of the Invention

[0004] The purpose of the present invention is to propose a modified phosphogypsum-based self-healing concrete and a preparation method thereof in view of the above deficiencies of the prior art.

[0005] The first object of the present invention is to provide a preparation method of a modified phosphogypsum-based self-healing concrete, which includes the following steps:

[0006] S1. Modify phosphogypsum with quicklime to obtain modified phosphogypsum;

[0007] S2. Weigh 140 - 164 parts of modified phosphogypsum, 40 - 60 parts of cement, 3 - 8 parts of calcium formate, 15 - 20 parts of self-healing agent, 0.1 - 0.8 parts of water reducing agent, 1 - 3 parts of sodium silicate solution, and 35 - 60 parts of water, mix and stir them, and mix evenly to obtain a modified phosphogypsum-based mixed slurry;

[0008] S3. Put the mixed slurry into a mold for curing to obtain modified phosphogypsum-based self-healing concrete;

[0009] Wherein, the self-healing agent is an acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer.

[0010] Furthermore, the specific operation of step S1 is: mixing the dried phosphogypsum with quicklime for sealing and modification to obtain modified phosphogypsum.

[0011] Furthermore, the time for mixed sealing modification is 20-30 hours.

[0012] Furthermore, the mass ratio of quicklime to phosphogypsum is 2-4:138-160.

[0013] Furthermore, the water reducer is a polycarboxylate water reducer.

[0014] Furthermore, the cement is P·O 42.5 grade silicate cement.

[0015] Furthermore, the specific operation of step S2 is: weighing modified phosphogypsum and cement to obtain a dry mix; stirring the self-healing agent, calcium formate, polycarboxylate water reducer, water glass solution and water in a volumetric bucket to obtain a liquid after sufficient mixing; then stirring the dry mix and the liquid to obtain a modified phosphogypsum-based mixed slurry.

[0016] Furthermore, the specific operation of step S3 is: loading the mixed slurry into a mold for grouting molding, standing and curing at room temperature for 24-48 hours, and standard curing for 3-28 days.

[0017] The second object of the present invention is to provide a modified phosphogypsum-based self-healing concrete prepared by the above-mentioned preparation method.

[0018] Beneficial effects of the present invention:

[0019] 1. The present invention adopts quicklime to neutralize and modify phosphogypsum, which can effectively improve the pH value of phosphogypsum, and at the same time, the content of soluble phosphorus and fluorine is significantly reduced. Soluble impurities in phosphogypsum, such as soluble phosphorus and fluorine, will react with calcium ions during the hydration process to generate insoluble substances such as calcium phosphate and calcium fluoride. These insoluble substances will cover the surface of phosphogypsum crystals, hindering the further dissolution and hydration of gypsum, resulting in coarsening of crystals and loose structure, thereby reducing density. With a small amount of addition, quicklime has a better effect on improving the structural density and compressive strength of concrete. 2% quicklime modified phosphogypsum has the best effect, and the 28d compressive strength of cement prepared using it can reach 45MPa.

[0020] 2. The present invention uses calcium formate to enhance the early strength of concrete. Calcium formate is introduced into concrete to ionize Ca 2+ , thereby increasing the Ca 2+ The concentration can accelerate C 3 The rate of S dissolution can also accelerate the crystallization of calcium hydroxide and promote the early hydration reaction. -It can form substances similar to ettringite, shorten the setting time of concrete paste, and thus increase the early strength.

[0021] 3. The self-healing agent of the present invention is acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer. Among them, the sulfonic acid group (-SO 3 H) and carboxyl group (-COOH) can react chemically with Ca(OH) in cement and phosphogypsum 2 to form stable chemical bonds and then form a cross-linked network as a whole, better improving its mechanical properties, being able to reduce the drying shrinkage of concrete and reduce the cracking risk. Modified phosphogypsum fills the pores and promotes the growth of later strength, and calcium formate accelerates the development of early strength. The combined action of the three enables the concrete to have excellent mechanical properties at different ages.

[0022] 4. The modified phosphogypsum and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer of the present invention jointly reduce the porosity of concrete, and calcium formate refines the microstructure. The synergy of the three can improve the impermeability, frost resistance and chemical erosion resistance of concrete.

[0023] 5. In a low-temperature or high-temperature environment, calcium formate and acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer of the present invention can ensure the normal hydration and strength development of concrete, enabling the concrete to adapt to various construction conditions.

[0024] 6. The present invention greatly solves a large amount of industrial solid waste phosphogypsum, reduces energy consumption. The raw materials of the present invention are derived from solid waste, making full use of solid waste such as phosphogypsum, alleviating the environmental pollution problems caused by waste accumulation, enabling the waste to be recycled resourcefully, and reducing energy consumption. Specific Embodiments

[0025] The following are specific embodiments of the present invention, which further describe the technical solutions of the present invention, but the present invention is not limited to these embodiments.

[0026] Example 1

[0027] A preparation method of modified phosphogypsum-based self-healing concrete in this embodiment is composed of the following raw materials in parts by weight: take 140 parts of modified phosphogypsum, 60 parts of cement, 3 parts of calcium formate, 15 parts of self-healing agent, 0.5 part of polycarboxylate water reducer, 2 parts of water glass solution, and 60 parts of water.

[0028] It includes the following steps:

[0029] S1: Phosphogypsum is dried in a constant-temperature drying oven at 50°C until the material is dried to a constant weight. Mix 2% quicklime with phosphogypsum and seal it for modification for 1 day to obtain modified phosphogypsum.

[0030] S2: According to the weight ratio of the raw materials, the modified phosphogypsum and cement are weighed, mixed and dry-mixed, and then put into a slurry mixer and mixed well to obtain a dry mix;

[0031] Stir acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer, calcium formate, polycarboxylic acid water reducer, water glass solution and water in a volumetric bucket to obtain a liquid after sufficient mixing; the acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer can be purchased or 2-acrylamide-2-methylpropane sulfonic acid, acrylic acid, initiator, coupling agent and other materials can be mixed and stirred to prepare a self-healing agent liquid;

[0032] The dry blend is mixed with the liquid according to the weight ratio of the raw materials, added into a mixer and stirred until the slurry is uniform to obtain a slurry;

[0033] S3: The material obtained in step S5 is placed into a mold for slurry injection molding, and vibrated on a vibration table for about 30 seconds to promote stable slurry molding, and then allowed to stand and solidify at room temperature for 48 hours.

[0034] After demoulding, the block samples were placed in a standard curing box for curing for 3 days, 7 days, and 28 days.

[0035] The temperature in the standard curing box should be set to 20±2°C, and the humidity should be ≥95%. The 3d, 7d, and 28d compressive strengths of each embodiment are tested according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0036] The 28d block samples were cut and cracked and cured at constant temperature for 0d, 7d and 28d. The compressive strength at different curing ages was measured, the data was recorded and the compressive strength recovery rate was calculated.

[0037] The compressive strength test results of the concrete of Example 1 of the present invention are shown in Table 1. It can be concluded that the 3d, 7d, and 28d compressive strengths of the concrete are 32.854 MPa, 41.582 MPa, and 45.936 MPa, respectively.

[0038] The compressive strength test results of the concrete of Example 1 of the present invention after curing are shown in Table 2. It can be concluded that the 0d, 7d, and 28d compressive strengths of the concrete are 42.319 MPa, 16.135 MPa, and 37.761 MPa, respectively, and the compressive strength recovery rate is 89.23%.

[0039] Example 2

[0040] A method for preparing modified phosphogypsum-based self-healing concrete in this embodiment is composed of the following raw materials in parts by weight: 150 parts of modified phosphogypsum, 50 parts of cement, 4 parts of calcium formate, 16 parts of self-healing agent, 0.5 parts of polycarboxylate water reducer, 2 parts of water glass solution, and 55 parts of water.

[0041] It includes the following steps:

[0042] S1: The phosphogypsum is dried in a constant temperature drying oven at 50 °C until the material is dried to a constant weight. 2% quicklime is mixed with the phosphogypsum and sealed for modification for 1 day to obtain modified phosphogypsum.

[0043] S2: According to the weight ratio of raw materials, weigh the modified phosphogypsum and cement, dry mix them and then put them into a neat paste mixer to mix evenly to obtain a dry mix;

[0044] Mix the acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, calcium formate, polycarboxylate water reducer, water glass solution and water evenly in a measuring bucket, and fully mix them to obtain a liquid;

[0045] The dry mix is mixed with the liquid prepared in S4 according to the weight ratio of raw materials, added to a mixer and stirred until the slurry is uniform to obtain a slurry;

[0046] S3: Pour the slurry into a mold for grouting molding, vibrate on a vibrating table for about 30 s to promote the stable molding of the slurry, and let it stand at room temperature for curing for 48 h.

[0047] After demolding, place the block samples in a standard curing box for curing for 3 days, 7 days and 28 days.

[0048] The temperature in the standard curing box should be set at 20 ± 2 °C, and the humidity ≥ 95%. According to GB / T50081-2002 "Standard Test Method for Mechanical Properties of Ordinary Concrete", test the 3d, 7d and 28d compressive strengths of each example.

[0049] The 28d block samples are cut to make seams and cured at a constant temperature for 0d, 7d and 28d, and the compressive strengths at different curing ages are measured respectively. Record the data and calculate the compressive strength recovery rate.

[0050] The test results of the compressive strength of the concrete in Example 2 of the present invention are shown in Table 1. It can be obtained that the 3d, 7d and 28d compressive strengths of the concrete are 33.254 MPa, 42.375 MPa and 46.623 MPa respectively.

[0051] The test results of the compressive strength of the concrete in Example 2 of the present invention after curing are shown in Table 2. It can be obtained that the 0d, 7d and 28d compressive strengths of the concrete are 43.596 MPa, 16.357 MPa and 38.89 MPa respectively, and the compressive strength recovery rate is 89.26%.

[0052] Example 3

[0053] A method for preparing modified phosphogypsum-based self-healing concrete in this embodiment is composed of the following raw materials in parts by weight: 155 parts of modified phosphogypsum, 45 parts of cement, 5 parts of calcium formate, 18 parts of self-healing agent, 0.5 parts of polycarboxylate water reducer, 2 parts of water glass solution, and 45 parts of water.

[0054] The following steps are involved:

[0055] S1: The phosphogypsum is dried in a constant temperature drying oven at 50°C until the material is dried to a constant weight. 2% quicklime is mixed with the phosphogypsum and sealed for modification for 1 day to obtain modified phosphogypsum.

[0056] S2: According to the weight ratio of the raw materials, the modified phosphogypsum and cement are weighed, mixed and dry-mixed, and then put into a slurry mixer and mixed well to obtain a dry mix;

[0057] Acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, calcium formate, polycarboxylic acid water reducer, water glass solution and water are stirred evenly in a volumetric bucket to obtain a liquid after sufficient mixing;

[0058] The dry blend is mixed with the liquid according to the weight ratio of the raw materials, added into a mixer and stirred until the slurry is uniform to obtain a slurry;

[0059] The slurry was loaded into a mold for grouting molding, and vibrated on a vibration table for about 30 seconds to promote stable molding of the slurry, and then allowed to stand and solidify at room temperature for 48 hours.

[0060] After demoulding, the block samples were placed in a standard curing box for curing for 3 days, 7 days, and 28 days.

[0061] The temperature in the standard curing box should be set to 20±2°C, and the humidity should be ≥95%. The 3d, 7d, and 28d compressive strengths of each embodiment are tested according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0062] The 28d block samples were cut and cracked and cured at constant temperature for 0d, 7d, and 28d. The compressive strength at different curing ages was measured, the data was recorded, and the compressive strength recovery rate was calculated.

[0063] The test results of the concrete of Example 3 of the present invention are shown in Table 1, and it can be concluded that the 3d, 7d, and 28d compressive strengths of the concrete are 34.943 MPa, 45.467 MPa, and 49.895 MPa, respectively.

[0064] The compressive strength test results of the concrete of Example 3 of the present invention after curing are shown in Table 2. It can be concluded that the 0d, 7d, and 28d compressive strengths of the concrete are 46.572 MPa, 17.78 MPa, and 41.591 MPa, respectively, and the compressive strength recovery rate is 89.3%.

[0065] Example 4

[0066] A method for preparing modified phosphogypsum-based self-healing concrete in this embodiment is composed of the following raw materials in parts by weight: 160 parts of modified phosphogypsum, 40 parts of cement, 6 parts of calcium formate, 20 parts of self-healing agent, 0.5 parts of polycarboxylate water reducer, 2 parts of water glass solution, 35 parts of water, etc.

[0067] The following steps are involved:

[0068] S1: The phosphogypsum is dried in a constant temperature drying oven at 50°C until the material is dried to a constant weight. 2% quicklime is mixed with the phosphogypsum and sealed for modification for 1 day to obtain modified phosphogypsum.

[0069] S2: According to the weight ratio of the raw materials, the modified phosphogypsum and cement are weighed, mixed and dry-mixed, and then put into a slurry mixer and mixed well to obtain a dry mix;

[0070] Self-healing agent acrylic acid-2-acrylamide-2-methylpropanesulfonic acid copolymer, calcium formate, polycarboxylic acid water reducer, water glass solution and water are stirred evenly in a volumetric bucket to obtain a liquid after sufficient mixing;

[0071] The dry blend is mixed with the liquid prepared in S4 according to the weight ratio of the raw materials, added into a mixer and stirred until the slurry is uniform to obtain a slurry;

[0072] S3: The slurry is loaded into a mold for grouting molding, and vibrated on a vibration table for about 30 seconds to promote stable molding of the slurry, and then left to solidify at room temperature for 48 hours.

[0073] After demoulding, the block samples were placed in a standard curing box for curing for 3 days, 7 days, and 28 days.

[0074] The temperature in the standard curing box should be set to 20±2°C, and the humidity should be ≥95%. The 3d, 7d, and 28d compressive strengths of each embodiment are tested according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0075] The 28d block samples were cut and cracked and cured at constant temperature for 0d, 7d, and 28d. The compressive strength at different curing ages was measured, the data was recorded, and the compressive strength recovery rate was calculated.

[0076] The test results of the concrete of Example 4 of the present invention are shown in Table 1, and it can be concluded that the 3d, 7d, and 28d compressive strengths of the concrete are 38.652 MPa, 46.655 MPa, and 56.842 MPa, respectively.

[0077] The compressive strength test results of the concrete of Example 4 of the present invention after curing are shown in Table 2. It can be concluded that the 0d, 7d, and 28d compressive strengths of the concrete are 52.578 MPa, 20.468 MPa, and 47.112 MPa, respectively, and the compressive strength recovery rate is 89.6%.

[0078] Example 5

[0079] A method for preparing modified phosphogypsum-based self-healing concrete in this embodiment is composed of the following raw materials in parts by weight: 160 parts of modified phosphogypsum, 40 parts of cement, 7 parts of calcium formate, 17 parts of self-healing agent, 0.5 parts of polycarboxylate water reducer, 2 parts of water glass solution, and 50 parts of water.

[0080] The following steps are involved:

[0081] S1: The phosphogypsum is dried in a constant temperature drying oven at 50°C until the material is dried to a constant weight. 2% quicklime is mixed with the phosphogypsum and sealed for modification for 1 day to obtain modified phosphogypsum.

[0082] S2: According to the weight ratio of the raw materials, the modified phosphogypsum and cement are weighed, mixed and dry-mixed, and then put into a slurry mixer and mixed well to obtain a dry mix;

[0083] Stir the self-healing agent, calcium formate, polycarboxylate water reducer, water glass solution and water in a volumetric bucket to obtain a liquid after sufficient mixing;

[0084] The dry blend is mixed with the liquid prepared in S4 according to the weight ratio of the raw materials, added into a mixer and stirred until the slurry is uniform to obtain a slurry;

[0085] S3: The material obtained in step S5 is placed into a mold for slurry injection molding, and vibrated on a vibration table for about 30 seconds to promote stable slurry molding, and then allowed to stand and solidify at room temperature for 48 hours.

[0086] After demoulding, the block samples were placed in a standard curing box for curing for 3 days, 7 days, and 28 days.

[0087] The temperature in the standard curing box should be set to 20±2°C, and the humidity should be ≥95%. The 3d, 7d, and 28d compressive strengths of each embodiment are tested according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0088] The 28d block samples were cut and cracked and cured at constant temperature for 0d, 7d, and 28d. The compressive strength at different curing ages was measured, the data was recorded, and the compressive strength recovery rate was calculated.

[0089] The test results of the concrete of Example 5 of the present invention are shown in Table 1, and it can be concluded that the 3d, 7d, and 28d compressive strengths of the concrete are 34.232 MPa, 46.353 MPa, and 47.625 MPa, respectively.

[0090] The compressive strength test results of the concrete of Example 5 of the present invention after curing are shown in Table 2. It can be concluded that the 0d, 7d, and 28d compressive strengths of the concrete are 44.576MPa, 18.136MPa, and 39.865MPa, respectively, and the compressive strength recovery rate is 89.43%.

[0091] Example 6

[0092] A method for preparing modified phosphogypsum-based self-healing concrete in this embodiment is composed of the following raw materials in parts by weight: 140 parts of modified phosphogypsum, 60 parts of cement, 8 parts of calcium formate, 15 parts of self-healing agent, 0.5 parts of polycarboxylate water reducer, 2 parts of water glass solution, and 50 parts of water.

[0093] The following steps are involved:

[0094] S1: The phosphogypsum is dried in a constant temperature drying oven at 50°C until the material is dried to a constant weight. 2% quicklime is mixed with the phosphogypsum and sealed for modification for 1 day to obtain modified phosphogypsum.

[0095] S2: According to the weight ratio of the raw materials, the modified phosphogypsum and cement are weighed, mixed and dry-mixed, and then put into a slurry mixer and mixed well to obtain a dry mix;

[0096] Self-healing agent acrylamide-2-methylpropanesulfonic acid copolymer, calcium formate, polycarboxylic acid water reducer, water glass solution and water are stirred evenly in a volumetric bucket to obtain a liquid after sufficient mixing;

[0097] The dry blend is mixed with the liquid prepared in S4 according to the weight ratio of the raw materials, added into a mixer and stirred until the slurry is uniform to obtain a slurry;

[0098] S3: The slurry is loaded into a mold for grouting molding, and vibrated on a vibration table for about 30 seconds to promote stable molding of the slurry, and then left to solidify at room temperature for 48 hours.

[0099] S4: After demoulding, the block samples were placed in a standard curing box for curing for 3 days, 7 days, and 28 days.

[0100] The temperature in the standard curing box should be set to 20±2°C, and the humidity should be ≥95%. The 3d, 7d, and 28d compressive strengths of each embodiment are tested according to GB / T50081-2002 "Standard for Test Methods for Mechanical Properties of Ordinary Concrete".

[0101] The 28d block samples were cut and cracked and cured at constant temperature for 0d, 7d, and 28d. The compressive strength at different curing ages was measured, the data was recorded, and the compressive strength recovery rate was calculated.

[0102] The test results of the concrete in Example 6 of the present invention are shown in Table 1. It can be obtained that the 3d, 7d, and 28d compressive strengths of the concrete are 32.268 MPa, 41.263 MPa, and 45.283 MPa respectively.

[0103] The test results of the compressive strength of the concrete in Example 6 of the present invention after curing are shown in Table 2. It can be obtained that the 0d, 7d, and 28d compressive strengths of the concrete are 42.039 MPa, 15.812 MPa, and 37.501 MPa respectively, and the compressive strength recovery rate is 89.2%.

[0104] Comparative Example 1

[0105] Unmodified phosphogypsum was used, and other steps were the same as those in Example 1.

[0106] The test results of the concrete in Comparative Example 1 are shown in Table 1. It can be obtained that the 3d, 7d, and 28d compressive strengths of the concrete are 17.331 MPa, 28.976 MPa, and 34.782 MPa respectively.

[0107] The test results of the compressive strength of the concrete after curing are shown in Table 2. It can be obtained that the 0d, 7d, and 28d compressive strengths of the concrete are 32.516 MPa, 10.381 MPa, and 28.81 MPa respectively, and the compressive strength recovery rate is 88.6%.

[0108] Comparative Example 2

[0109] The self-healing agent acrylamide-2-methylpropanesulfonic acid copolymer was not added, and other steps were the same as those in Example 1.

[0110] The test results of the concrete in Comparative Example 2 are shown in Table 1. It can be obtained that the 3d, 7d, and 28d compressive strengths of the concrete are 7.316 MPa, 15.583 MPa, and 19.672 MPa respectively.

[0111] The test results of the compressive strength of the concrete after curing are shown in Table 2. It can be obtained that the 0d, 7d, and 28d compressive strengths of the concrete are 16.214 MPa, 4.136 MPa, and 9.695 MPa respectively, and the compressive strength recovery rate is 59.8%.

[0112] Table 1 Test results of the compressive strength of the concrete in Examples 1-6

[0113]

[0114] Table 2 Test results of the compressive strength and compressive strength recovery rate of the concrete in Examples 1-6 after cutting, creating joints, and constant temperature curing

[0115]

[0116] Where not otherwise involved, it shall apply to the prior art.

[0117] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and not for limiting the scope of the present invention. Those skilled in the technical field to which the present invention pertains may make various modifications or supplements to the specific embodiments described or use similar means for substitution, but will not deviate from the direction of the present invention or exceed the scope defined by the appended claims. Those skilled in the art should understand that any modifications, equivalent substitutions, improvements, etc. made to the above embodiments based on the technical essence of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for preparing modified phosphogypsum-based self-healing concrete, characterized in that: The steps include: S1. Modifying phosphogypsum using quicklime to obtain modified phosphogypsum; S2, weighing 140-164 parts of modified phosphogypsum, 40-60 parts of cement, 3-8 parts of calcium formate, 15-20 parts of self-healing agent, 0.1-0.8 parts of water reducer, 1-3 parts of water glass solution and 35-60 parts of water, mixing and stirring, and mixing evenly to obtain a modified phosphogypsum-based mixed slurry; S3, putting the mixed slurry into a mold for curing to obtain modified phosphogypsum-based self-healing concrete; Wherein, the self-healing agent is acrylic acid-2-acrylamide-2-methylpropane sulfonic acid copolymer.

2. The preparation method according to claim 1, characterized in that: The specific operation of step S1 is: mixing the dried phosphogypsum with quicklime for sealing and modification to obtain modified phosphogypsum.

3. The preparation method according to claim 1, characterized in that: The time for mixed sealing modification is 20-30h.

4. The preparation method according to claim 1, characterized in that: The mass ratio of quicklime to phosphogypsum is 2-4:138-160.

5. The preparation method according to claim 1, characterized in that: The water reducer is a polycarboxylate water reducer.

6. The preparation method according to claim 1, characterized in that: The cement is P·O 42.5 grade silicate cement.

7. The preparation method according to claim 1, characterized in that: The specific operation of step S2 is: weighing the modified phosphogypsum and cement to obtain a dry mix; The self-healing agent, calcium formate, polycarboxylate water reducer, water glass solution and water are stirred evenly in a volumetric bucket to obtain a liquid after being fully mixed; Then the dry mixture is evenly mixed with the liquid to obtain a modified phosphogypsum-based mixed slurry.

8. The preparation method according to claim 1, characterized in that: The specific operation of step S3 is: loading the mixed slurry into a mold for grouting molding, standing and curing at room temperature for 24-48 hours, and standard curing for 3-28 days.

9. A modified phosphogypsum-based self-healing concrete prepared by the preparation method according to any one of claims 1 to 8.

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