Phosphogypsum-based luminous concrete and preparation method thereof

Abstract

The invention provides ardealite-based luminous concrete and a preparation method thereof, and belongs to the field of building materials, the ardealite-based luminous concrete comprises a base layer and a facing layer; the base layer is prepared from the following raw materials in parts by weight: 80 to 90 parts of modified phosphogypsum, 10 to 20 parts of aggregate, 1 to 2 parts of ultrafine powder and 10 to 18 parts of water; the facing layer is prepared from the following raw materials in parts by weight: 30-50 parts of white cement, 30-50 parts of quartz sand, 0.5-2 parts of a luminescent material, 1-2 parts of a photocatalyst and 10-16 parts of water. According to the phosphogypsum-based luminescent concrete and the preparation method thereof, a treatment process of phosphogypsum is optimized, modified phosphogypsum is taken as a main material to form a base material with high strength and good durability, and then the base material is combined with a facing layer in a luminescent manner to form the phosphogypsum-based luminescent concrete, and meanwhile, the concrete and masonry are endowed with excellent luminescent properties and mechanical properties and can better adapt to various environmental conditions; the phosphogypsum-based luminous concrete disclosed by the invention adopts a mechanical press molding mode, and can be used after being subjected to secondary mechanical press molding and curing.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a phosphogypsum-based luminous concrete and a preparation method thereof. BACKGROUND

[0002] Phosphogypsum is a main by-product of phosphate fertilizer industry, and its main component is calcium sulfate dihydrate (CaSO4·2H2O), usually in gray or gray-black. With the rapid development of global phosphate fertilizer industry, the production of phosphogypsum is increasing. At present, the global phosphogypsum stockpile has reached 6 billion tons, with an annual increase of about 150 million tons. Such a large amount of phosphogypsum accumulation not only occupies a large amount of land resources, but also may pollute the environment, for example, a small amount of phosphorus, fluorine and free acid and other harmful substances contained therein, long-term accumulation will pollute surface and underground water, affect soil quality and biodiversity.

[0003] At the same time, with the popularization of green building and smart building concept, modern building materials not only need to meet the basic structural and functional requirements, but also need to have higher environmental performance and additional functions. For example, as a new building material, luminous concrete has attracted attention because of its unique night lighting effect. It can provide certain lighting at night, reduce lighting energy consumption, and also can be used as a decorative material to improve the aesthetics of buildings. However, the preparation cost of traditional luminous concrete is high, and the process is complex, which limits its large-scale application. Moreover, there are still some deficiencies in the mechanical properties and luminous properties of traditional luminous concrete. In traditional luminous concrete, the addition of long afterglow luminescent material will weaken the mechanical strength of the concrete, and the luminescent material may hydrolyze in a humid environment, resulting in a decrease in the durability of the concrete; the chemical stability of the luminescent material in the concrete is poor, which may lead to a shortening of the afterglow time.

[0004] Therefore, how to effectively utilize phosphogypsum and develop a luminous concrete with lower cost and simpler process has become a problem to be solved in the field of building materials. On the one hand, it is necessary to further explore the resource utilization approach of phosphogypsum to reduce its impact on the environment; on the other hand, it is necessary to introduce innovative technology in the preparation process of luminous concrete to reduce production cost and improve material performance to meet the development needs of green building and smart building. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a phosphogypsum-based luminous concrete and a preparation method thereof, aiming to solve the technical problem of poor mechanical properties and luminous properties of existing luminous concrete.

[0006] In a first aspect, the present application provides a phosphogypsum-based luminous concrete, comprising a base layer and a finishing layer; the base layer raw materials comprise, by weight fraction: modified phosphogypsum 80-90 parts, aggregate 10-20 parts, ultra-fine powder 1-2 parts, and water 10-18 parts; The finishing layer raw materials comprise, by weight fraction: white cement 30-50 parts, quartz sand 30-50 parts, luminous material 0.5-2 parts, photocatalyst 1-2 parts, and water 10-16 parts.

[0007] In the present application, the aggregate is traditional sand or recycled lightweight aggregate sand; the traditional sand or recycled lightweight aggregate sand is added to improve the mixing homogeneity and reduce the compression ratio during the compression molding of the mixer.

[0008] Preferably, the preparation method of the modified phosphogypsum comprises the following steps: crushing and screening the phosphogypsum, and calcining at 180-400℃ for 15-40min to obtain the modified phosphogypsum.

[0009] Preferably, the size of the phosphogypsum particles after screening is controlled to be 0.075-0.15mm when the phosphogypsum is crushed and screened.

[0010] Preferably, the luminous material comprises long-afterglow fluorescent powder; and the photocatalyst comprises at least one of ZrO2 and TiO2.

[0011] Preferably, the long-afterglow fluorescent powder comprises Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ .

[0012] Preferably, the mass ratio of Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ is (2-5):3.

[0013] Preferably, the mass ratio of Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ is 5:3 In the embodiments of the present application, the ultra-fine powder comprises at least one of coal ash ultra-fine powder, silica ash ultra-fine powder, and slag ultra-fine powder.

[0014] In a second aspect, the present application provides a preparation method of a phosphogypsum-based luminous concrete, comprising the following steps: S1, aggregate, modified phosphogypsum, and ultra-fine powder are weighed by weight fraction, stirred and mixed uniformly to obtain a first mixture; water is added to the first mixture for homogenization, and then the mixture is once distributed into a mold, and after once static compression molding, a phosphogypsum-based luminous concrete product base layer is obtained; S2, the white cement, quartz sand, luminescent material, photocatalyst and water are weighed by weight parts, mixed uniformly to obtain a second mixture; the second mixture is secondly distributed on the phosphogypsum-based luminescent concrete product base layer, and secondly formed by static pressure to obtain a phosphogypsum-based luminescent concrete product facing layer; S3, the sample prepared in step S2 is demolded and cured to obtain a phosphogypsum-based luminescent concrete.

[0015] Preferably, in step S1, the stirring speed is 50-300 rpm; and the homogenizing speed is 150-250 rpm.

[0016] Preferably, the pressure of the first static pressure forming is 20 MPa, and the static pressure time is 10-20 s; the pressure of the second static pressure forming is 20 MPa, and the static pressure time is 5-10 s.

[0017] Preferably, the curing condition is that the temperature is 40-60 DEG C, and the humidity is less than or equal to 50%.

[0018] The technical scheme principle of the present application is as follows: The modified phosphogypsum can significantly improve its performance in concrete by calcination pretreatment method. Calcination can remove impurities in phosphogypsum, and at the same time convert it into semi-hydrated gypsum with higher reactivity. Thus, the hydration reaction efficiency of cement and other cementitious materials is improved. The modified phosphogypsum, aggregate, ultra-fine powder and white cement jointly act through chemical reaction and physical filling, which improves the compactness and strength of the concrete.

[0019] The luminescent material uses Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ The compound can realize wider light spectrum coverage under certain proportion, so that it presents brighter and more uniform light effect in night or low light conditions. The photocatalyst can produce photo-generated electrons and holes under light conditions, which can interact with the luminescent material to enhance the excitation efficiency of the luminescent material, thereby improving the light intensity.

[0020] Compared with the prior art, the present application has the following advantages: (1) The modified phosphogypsum prepared by calcination pretreatment process is more simple and economical, and can realize large-scale application of phosphogypsum. By optimizing the formula and pretreatment method, the modified phosphogypsum is used as the main material to form a substrate with high strength and good durability, and then the surface layer is formed by luminescent composite to form a phosphogypsum-based luminescent concrete, which has significantly enhanced mechanical properties and can better adapt to various environmental conditions.

[0021] (2) The combination of two long afterglow fluorescent materials can achieve a wider light spectrum coverage, and after absorbing light energy, they can continue to emit light. After these materials are uniformly distributed in the concrete, they can provide continuous light effect at night or in low light conditions. Photocatalysts can generate photo-generated electrons and holes under light, and these active species can further excite long afterglow fluorescent materials to prolong their light emission time. The combination of light emitting materials and photocatalysts improves the light emitting performance of phosphogypsum-based light emitting concrete.

[0022] (3) Change the molding method of traditional cast cement-based light emitting materials. The concrete base material is directly molded after being proportioned, mixed, homogenized, molded, and pressed. When the composite finishing material is pressed, it is attached to the already molded and high-strength gypsum base material, which increases the speed of transportation and delivery. DETAILED DESCRIPTION

[0023] The embodiments of the technical solutions of the present application will be described in detail below. The following examples are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, but cannot limit the protection scope of the present application.

[0024] If the specific technology or condition is not specified in the examples, it is carried out according to the technology or condition described in the literature in the art or according to the product instruction. If the reagent or instrument is not specified by the manufacturer, it is a conventional product that can be obtained from the market.

[0025] The aggregate in the following examples of the present application is a traditional sand and stone.

[0026] I. Preparation method Example 1 A preparation method of a phosphogypsum-based light emitting concrete, comprising the following steps: S1, phosphogypsum pretreatment: crushing and sieving the phosphogypsum, selecting 0.075~0.15mm size particles, calcining at 200℃ for 35min to obtain modified phosphogypsum; S2, take 85 parts of modified phosphogypsum, 18 parts of aggregate, and 2 parts of silica super fine powder by weight, mix uniformly at 100rpm, send to the pulverizer for crushing to obtain the mixture; add 15 parts of water to the mixture for homogenization, the homogenization speed is 150rpm, obtain the homogenized mixture; uniformly distribute the homogenized mixture to the mold, once static pressure forming (pressure is 20MPa, static pressure time is 10s), form the phosphogypsum-based light emitting concrete product base layer; S3, take 42 parts of white cement, 35 parts of quartz sand, and 0.8 parts of light emitting material (Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+S3, take white cement 30 parts by weight, quartz sand 50 parts, luminescent material 2 parts (Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ The mass ratio of 4:3), photocatalyst (TiO2) 2 parts and water 10 parts, after mixing, on the phosphogypsum-based luminescent concrete product base layer obtained in step S1 Secondary distribution, secondary static pressure forming (pressure is 20MPa, static pressure time is 8s), forming phosphogypsum-based luminescent concrete product finish layer; S4, the sample obtained in step S2 is demolded and placed at 50℃, humidity 40% for 28d, to obtain phosphogypsum-based luminescent concrete.

[0027] Example 2 A preparation method of a phosphogypsum-based luminescent concrete, comprising the following steps: S1, phosphogypsum pretreatment: crushing and screening the phosphogypsum, selecting 0.075~0.15mm size particles and calcining at 300℃ for 25min to obtain modified phosphogypsum; S2, take modified phosphogypsum 80 parts, aggregate 20 parts, coal ash superfine powder 2 parts by weight, mix uniformly under 150rpm stirring speed, send to the pulverizer after crushing to obtain the mixture; add 10 parts of water to the mixture for homogenization, the homogenization speed is 200rpm, to obtain the homogenized mixture; uniformly distribute the homogenized mixture to the mold, once static pressure forming (pressure is 20MPa, static pressure time is 15s), forming phosphogypsum-based luminescent concrete product base layer; S3, take white cement 30 parts by weight, quartz sand 50 parts, luminescent material 2 parts (Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ The mass ratio of 4:3), photocatalyst (TiO2) 2 parts and water 10 parts, after mixing, on the phosphogypsum-based luminescent concrete product base layer obtained in step S1 Secondary distribution, secondary static pressure forming (pressure is 20MPa, static pressure time is 8s), forming phosphogypsum-based luminescent concrete product finish layer; S4, the sample obtained in step S2 is demolded and placed at 50℃, humidity 40% for 28d, to obtain phosphogypsum-based luminescent concrete.

[0028] Example 3 A preparation method of a phosphogypsum-based luminescent concrete, comprising the following steps: S1, phosphogypsum pretreatment: crushing and screening the phosphogypsum, selecting 0.075~0.15mm size particles and calcining at 300℃ for 25min to obtain modified phosphogypsum; S2, 90 parts by weight of modified phosphogypsum, 10 parts by weight of aggregate and 1 part by weight of superfine powder were weighed and stirred uniformly at a speed of 200 rpm, and then sent to a pulverizer to obtain a mixture; 18 parts of water was added to the mixture to homogenize, and the homogenization speed was 250 rpm, to obtain a homogenized mixture; the homogenized mixture was uniformly distributed to a mold, and then once static pressure forming (20 MPa, static pressure time was 20 s) was performed to form a phosphogypsum-based luminous concrete product base layer; S3, 50 parts by weight of white cement, 30 parts by weight of quartz sand, 2 parts by weight of luminous material (Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ , a mass ratio of 5:3), 2 parts of photocatalyst (TiO2) and 16 parts of water were uniformly mixed and then secondarily distributed on the phosphogypsum-based luminous concrete product base layer obtained in step S1, and then twice static pressure forming (pressure was 20 MPa, and static pressure time was 10 s) was performed to form a phosphogypsum-based luminous concrete product finishing layer. S4, the sample obtained in step S2 was demolded and then cured at 50°C and a humidity of 40% for 28 days to obtain a phosphogypsum-based luminous concrete.

[0029] Example 4 The difference between this example and example 1 is that in step S1, the calcination temperature of the phosphogypsum is 400°C.

[0030] Example 5 The difference between this example and example 1 is that in step S1, the calcination temperature of the phosphogypsum is 180°C.

[0031] Example 6 The difference between this example and example 1 is that in step S1, the calcination time of the phosphogypsum is 40 min.

[0032] Example 7 The difference between this example and example 1 is that in step S1, the calcination time of the phosphogypsum is 15 min.

[0033] Example 8 The difference between this example and example 1 is that the mass ratio of the luminous material Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ is 5:3.

[0034] Example 9 The difference between this example and example 1 is that the mass ratio of the luminous material Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+The mass ratio of the phosphogypsum to the cement is 2:3.

[0035] Comparative Example 1 The difference between this comparative example and Example 1 is that the phosphogypsum is not calcined.

[0036] Comparative Example 2 The difference between this comparative example and Example 1 is that the luminescent material is single Sr2TiO4:Eu 3+ .

[0037] Comparative Example 3 The difference between this comparative example and Example 1 is that the luminescent material is single Sr2MgSi2O7:Eu 2+ ,Dy 3+ .

[0038] II. Test Methods 1. Mechanical property test of phosphogypsum-based luminescent concrete The phosphogypsum-based luminescent concrete test blocks prepared in Examples 1-9 and Comparative Examples 1-3 were tested for compressive strength and tensile strength according to GB / T50081-2019 “Standard Test Methods for Physical and Mechanical Properties of Concrete”. Three parallel test blocks were tested for each group, and the compressive strength and tensile strength of each group were recorded, and the average value was taken as the test result. The test results are shown in Table 1.

[0039] 2. Luminescent performance test of phosphogypsum-based luminescent concrete According to GBT24981.2-2020 “Test Methods for Rare Earth Long Afterglow Fluorescent Powder Part 2: Determination of Afterglow Brightness”, the phosphogypsum-based luminescent concrete test blocks prepared in Examples 1-9 and Comparative Examples 1-3 were irradiated with a daylight lamp with an illuminance of 6000 K for 10 min, and then placed in a dark environment. The initial brightness value of the concrete product was measured using a luminance meter and the afterglow time was counted. The test results are shown in Table 1.

[0040] III. Analysis of test results of each example and comparative example Table 1. Mechanical property and luminescent performance test results of phosphogypsum-based luminescent concrete

[0041] The test results in Table 1 show that the phosphogypsum-based luminous concrete prepared by the present application has excellent mechanical properties and luminous properties. The results of Example 1, Examples 4-7 and Comparative Example 1 show that the calcination temperature and calcination time of phosphogypsum have a greater impact on the mechanical properties. Insufficient calcination will result in incomplete conversion of dihydrate gypsum in the product, and the strength will decrease; while the calcination time is too long or the temperature is too high, part of the dihydrate gypsum and hemihydrate gypsum is converted into anhydrous gypsum, resulting in an increase in the content of anhydrous gypsum. Since the hydration reaction rate of anhydrous gypsum is lower than that of hemihydrate gypsum, the crystal nucleus formed by anhydrous gypsum is relatively tight, which will occupy a certain space and limit the contact between water molecules and hemihydrate gypsum, thereby delaying the hydration reaction of hemihydrate gypsum. This hindering effect will result in a decrease in the overall hydration reaction rate, which will prolong the setting and hardening time of gypsum, thereby reducing the compressive strength and flexural strength of the concrete prepared therefrom. The results of Example 1, Examples 8-9 and Comparative Examples 2-3 show that the two kinds of long afterglow fluorescent materials can realize wider light spectrum coverage when compounded in a certain proportion, and can continuously emit light after absorbing light energy. These materials can provide continuous light effect at night or in low light conditions when uniformly distributed in the concrete.

[0042] It should be noted that the present application is not limited to the above-mentioned embodiments. The above-mentioned embodiments are only examples, and embodiments having the same technical idea and substantially the same function and effect within the scope of the technical solutions of the present application are all included in the technical scope of the present application. In addition, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, and other ways constructed by combining part of the components in the embodiments are also included in the scope of the present application.

Claims

1. A phosphogypsum-based luminescent concrete, characterized in that, It includes a base layer and a finishing layer; the base layer raw materials include, by weight: 80-90 parts modified phosphogypsum, 10-20 parts aggregate, 1-2 parts ultrafine powder and 10-18 parts water; The finishing layer raw materials, by weight, include: 30-50 parts white cement, 30-50 parts quartz sand, 0.5-2 parts luminescent material, 1-2 parts photocatalyst, and 10-16 parts water.

2. The phosphogypsum-based luminescent concrete according to claim 1, characterized in that, The preparation method of the modified phosphogypsum includes the following steps: crushing and sieving the phosphogypsum, and calcining it at 180~400℃ for 15~40min to obtain the modified phosphogypsum.

3. The phosphogypsum-based luminescent concrete according to claim 2, characterized in that, When crushing and screening phosphogypsum, the size of the phosphogypsum particles after screening is controlled to be 0.075~0.15 mm.

4. The phosphogypsum-based luminescent concrete according to claim 1, characterized in that, The luminescent material includes a long afterglow phosphor; the photocatalyst includes at least one of ZrO2 and TiO2.

5. The phosphogypsum-based luminescent concrete according to claim 4, characterized in that, The long afterglow phosphor includes Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ The Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ The mass ratio is (2~5):

3.

6. The phosphogypsum-based luminescent concrete according to claim 5, characterized in that, The Sr2TiO4:Eu 3+ and Sr2MgSi2O7:Eu 2+ ,Dy 3+ The mass ratio is 5:

3.

7. A method for preparing phosphogypsum-based luminescent concrete as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. Weigh the aggregate, modified phosphogypsum, and ultrafine powder according to the weight parts, stir and mix them to obtain the first mixture; add water to the first mixture for homogenization, then spread the mixture into the mold in one go, and after one static pressing, obtain the base layer of phosphogypsum-based luminescent concrete product. S2. Weigh out white cement, quartz sand, luminescent material, photocatalyst and water by weight, mix them evenly to obtain a second mixture; spread the second mixture on the base layer of the phosphogypsum-based luminescent concrete product for a second time, and then perform a second static pressing to obtain the finishing layer of the phosphogypsum-based luminescent concrete product. S3. After demolding the sample obtained in step S2, cure it to obtain phosphogypsum-based luminescent concrete.

8. The method for preparing phosphogypsum-based luminescent concrete according to claim 7, characterized in that, In step S1, the stirring speed is 50~300 rpm; the homogenization speed is 150~250 rpm.

9. The method for preparing phosphogypsum-based luminescent concrete according to claim 7, characterized in that, The pressure for the first static pressing is 20 MPa, and the static pressing time is 10-20 s; the pressure for the second static pressing is 20 MPa, and the static pressing time is 5-10 s.

10. The method for preparing phosphogypsum-based luminescent concrete according to claim 7, characterized in that, The maintenance conditions are: temperature 40~60℃, humidity ≤50%.

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