High-durability anhydrous-semi-hydrated phosphogypsum phosphorus slag curb and preparation method thereof

Abstract

The invention provides a high-durability anhydrous-semi-hydrated phosphogypsum phosphorus slag curb and a preparation method of the high-durability anhydrous-semi-hydrated phosphogypsum phosphorus slag curb. The curb is prepared by taking ardealite and phosphorus slag industrial solid waste materials as main raw materials, so that the problems of insufficient early strength, high water absorption rate, poor durability, poor crack resistance, low fluidity, high cost and the like of the traditional curb are solved. The invention also provides a preparation method of the high-durability anhydrous-semi-hydrated phosphogypsum phosphorus slag kerb.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to a high-durability anhydrous-hemihydrate phosphogypsum slag curbstone and its preparation method. Background Technology

[0002] As a crucial basic industry, the phosphate chemical industry generates massive amounts of industrial solid waste, specifically phosphogypsum, during the production of core products such as phosphoric acid and phosphate fertilizers. This waste not only occupies valuable land resources for extended periods but also poses a risk of phosphorus, fluorine, and heavy metal ion migration due to rainwater leaching, leading to severe environmental problems such as soil salinization and groundwater pollution. Its resource utilization has become a core bottleneck restricting the green transformation of the phosphate chemical industry. Currently, the application of phosphogypsum is mainly concentrated in gypsum board production and is only suitable for dry indoor environments. Expanding its application in "wet" environments has become a pressing technological challenge for the industry.

[0003] Curbstones, as a key supporting material for road construction, are mainly divided into two categories: natural stone curbstones and ordinary concrete curbstones. While natural stone curbstones possess excellent durability, resilience, and aesthetic value, natural stone is a non-renewable resource, and the entire chain from mining and processing to transportation is costly. Large-scale application could easily lead to resource depletion and ecological damage. Ordinary concrete curbstones use cement, sand, and gravel as their main raw materials, resulting in relatively lower costs. However, cement production generates significant carbon emissions, and sand and gravel are also non-renewable resources. Under the concept of green development, their environmental performance shortcomings are becoming increasingly prominent. Therefore, developing new types of curbstones that combine environmental friendliness, superior performance, and cost advantages has become a development trend in the road construction materials industry.

[0004] Existing technological explorations have included attempts to use phosphogypsum as a cementing material to prepare curb stones, but several technical drawbacks remain: curb stones using phosphogypsum as the main cementing material are prone to early drying shrinkage and cracking, affecting structural stability; if traditional sand and gravel are used as aggregates, the slurry is prone to stratification and aggregate settling during preparation, significantly weakening the overall performance of the product; simultaneously, the rapid hardening speed and strong thixotropic properties of hemihydrate phosphogypsum lead to a significant reduction in the initial fluidity of the material, making it difficult to meet the process requirements of industrial mass production. Furthermore, traditional gypsum-based curb stones generally suffer from poor water resistance, high water absorption, and insufficient frost resistance, limiting their application in humid outdoor environments and cold regions. Therefore, overcoming these existing technological shortcomings and developing a highly durable curb stone that uses industrial solid waste as the main raw material, possesses excellent fluidity, strength, water resistance, and frost resistance, and has controllable production costs has become an urgent technical problem to be solved. Summary of the Invention

[0005] The present invention aims to at least solve one of the aforementioned technical problems existing in the prior art. To this end, the present invention provides a high-durability anhydrous-hemihydrate phosphogypsum and phosphate slag curbstone, which is prepared using phosphogypsum and phosphate slag industrial solid waste materials as the main raw materials to solve the problems of insufficient early strength, high water absorption, poor durability, poor crack resistance, low fluidity and high cost of traditional curbstones.

[0006] This invention also provides a method for preparing highly durable anhydrous-hemihydrate phosphogypsum slag curb stones.

[0007] The first aspect of this invention provides a high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw materials for which are prepared by weight include:

[0008] Anhydrous phosphogypsum: 600-700 parts Hemihydrate phosphogypsum: 100-350 parts Gypsum modifier: 60-120 parts, Silicate cement: 60-250 parts Granular yellow phosphorus slag: 200-600 parts Polycarboxylate superplasticizer: 1-5 parts Defoamer: 1-5 parts Water: 300-500 servings.

[0009] The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone of the present invention has at least the following beneficial effects: Achieving efficient resource utilization of solid waste: The curbstone of this invention uses industrial solid waste such as anhydrous phosphogypsum, hemihydrate phosphogypsum, and granular yellow phosphorus slag as core raw materials, with solid waste materials accounting for up to 90%. It can absorb phosphogypsum, phosphorus slag, and other solid waste generated by the phosphorus chemical industry on a large scale, effectively solving the problems of solid waste occupying land and polluting the environment, and helping the phosphorus chemical industry achieve green transformation. Compared with traditional curbstones that rely on non-renewable resources such as natural stone and sand, this solution significantly reduces the consumption of natural resources and reduces carbon emissions from cement use, which is in line with the development trend of green building materials.

[0010] With superior performance and adaptability to diverse applications: The raw materials are scientifically and rationally formulated. Anhydrous phosphogypsum, after high-temperature firing, exhibits excellent fluidity and water resistance. Upon hydration, it forms short columnar dihydrate gypsum crystals, enhancing product volume stability. Hemihydrate phosphogypsum ensures a shorter curing cycle. The synergistic effect of both ensures both production process compatibility and product stability. Calcium oxides in the gypsum modifier can activate the potential activity of phosphogypsum, while basalt fibers enhance structural crack resistance. Combined with the pore-filling effect of micro-powder, this significantly reduces product water absorption. Polycarboxylate-based water-reducing agents reduce water consumption and porosity, while silicone-based defoamers eliminate harmful bubbles, all effectively improving product density. The final product achieves a 28-day compressive strength of C30 concrete grade, with a water absorption rate controlled below 6%, a softening coefficient greater than 0.85, and a mass loss of less than 2% and a strength loss of less than 20% after 25 freeze-thaw cycles. It fully meets the requirements of JC / T899-2016 "Concrete Curbstone" standard, and its water resistance, freeze resistance, and crack resistance are significantly improved, making it suitable for use in humid outdoor environments and cold regions.

[0011] Convenient production and reduced overall costs: The raw material combination ensures that the initial flowability of the mixture exceeds 120mm, enabling self-flow and self-compacting. The casting process can be completed within 10 minutes, meeting the process requirements for industrialized mass production. The rapid hardening speed of hemihydrate phosphogypsum shortens the curing cycle, allowing for demolding after 24 hours and enabling rapid mold turnover, significantly improving production efficiency and product qualification rate while reducing labor costs. Furthermore, replacing traditional sand and gravel aggregates with granular yellow phosphorus slag not only provides readily available and inexpensive materials but also resists the drying shrinkage of cementitious materials and disperses evenly in the slurry, further optimizing product performance while reducing material costs. The final material cost can be reduced to approximately 12.66 yuan / m³, offering a significant price advantage compared to traditional curb stones and existing phosphogypsum-based curb stones.

[0012] Expanding application boundaries with broad market prospects: Breaking through the traditional limitation of phosphogypsum being only suitable for indoor dry environments, it successfully promotes the application of gypsum-based materials in wet road areas, providing a new path for the resource utilization of phosphogypsum. The product is easy to construct, has reliable strength, outstanding water resistance and frost resistance, and its overall cost is controllable. It can be widely used in various infrastructure construction projects such as urban roads, highways, and park roads, with broad market application prospects.

[0013] According to some embodiments of the present invention, the raw materials for preparation, by weight, include: Anhydrous phosphogypsum 616-693 parts, 154-339 parts of hemihydrate phosphogypsum 77-108 parts of gypsum modifier, Portland cement 77-231 parts, 231-570 parts of granular yellow phosphorus slag 2-3 parts of polycarboxylate superplasticizer 1-2 parts of defoamer 462-493 portions of water.

[0014] According to some embodiments of the present invention, the anhydrous phosphogypsum is prepared by firing undisturbed phosphogypsum at a high temperature of 800~1200℃.

[0015] According to some embodiments of the present invention, the firing temperature of the anhydrous phosphogypsum is any value among 800℃, 850℃, 900℃, 950℃, 1000℃, 1050℃, 1100℃, 1150℃, and 1200℃, such as 950℃, or any range formed by both, such as 900℃ to 1000℃.

[0016] The anhydrous phosphogypsum is produced by firing undisturbed phosphogypsum at a high temperature of 800~1200℃, exhibiting excellent fluidity and facilitating production operations. The hydration of the plate-shaped anhydrous phosphogypsum produces short columnar dihydrate gypsum crystals, which offer better water resistance and volume stability, thereby improving product quality.

[0017] According to some embodiments of the present invention, the hemihydrate phosphogypsum is fired at a high temperature of 150~300℃.

[0018] According to some embodiments of the present invention, the firing temperature of the hemihydrate phosphogypsum is any value among 150°C, 200°C, 250°C, and 300°C, such as 200°C, or any range formed by both, such as 200°C to 250°C.

[0019] The hemihydrate phosphogypsum is made by firing undisturbed phosphogypsum at a high temperature of 150~300℃. Its fast hardening speed ensures a shorter curing cycle, enabling rapid mold turnover and thus improving product production efficiency.

[0020] According to some embodiments of the present invention, the gypsum modifier mainly consists of calcium oxide and basalt fiber, which can activate the potential activity of anhydrous phosphogypsum and combine with its own hydraulic characteristics to form a hydraulic hydration product with phosphogypsum. Simultaneously, it can improve the structural crack resistance through basalt fiber, refine the structure by filling pores with micropowder, reduce water penetration, and thus reduce water absorption and enhance water resistance.

[0021] According to some embodiments of the present invention, the silicate cement is PO.42.5 grade cement. This grade of cement not only activates the potential activity of anhydrous phosphogypsum but also improves the water resistance of the product.

[0022] According to some embodiments of the present invention, the fineness modulus of the granular yellow phosphorus slag is 3-4. Lightweight phosphorus slag aggregate can resist the drying shrinkage of cementitious materials and be uniformly dispersed in the slurry, improving product stability and uniformity. Moreover, using solid waste phosphorus slag as aggregate can significantly reduce material costs.

[0023] According to some embodiments of the present invention, the fineness modulus of the granular yellow phosphorus slag is 3.1-3.8.

[0024] According to some embodiments of the present invention, the water reduction rate of the polycarboxylate superplasticizer is 30-40%. This can reduce water consumption, decrease porosity, and enhance density.

[0025] According to some embodiments of the present invention, the defoamer is an organosilicon defoamer. It can solve the performance defects caused by harmful air bubbles during the preparation and molding of curb stones, and enhance density.

[0026] A second aspect of the present invention provides a method for preparing high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to the first aspect of the present invention, comprising the following steps: S1: Mix the anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, and defoamer in proportion to obtain a premix; add the polycarboxylate superplasticizer to water and stir evenly to obtain a premix liquid. S2: The premixed material and premixed liquid are stirred and treated, poured into molds, and then naturally cured indoors. After demolding, the high-durability anhydrous-semi-hydrated phosphogypsum slag curbstone is obtained.

[0027] The method for preparing high-durability anhydrous-hemihydrate phosphogypsum slag curbstone of the present invention has at least the following beneficial effects: The scientifically sound process ensures stable product performance: The steps are designed to align with the characteristics of the raw materials. In S1, anhydrous phosphogypsum, hemihydrate phosphogypsum, and other solid raw materials are first dry-mixed evenly with defoamer. Then, polycarboxylate superplasticizer is separately mixed with water to prepare a premixed liquid. This avoids uneven dispersion caused by direct contact between the superplasticizer and solid powder, ensuring that the superplasticizer fully exerts its 30-40% water-reducing effect, effectively reducing the porosity of the mixture and increasing its density. Simultaneously, the defoamer is pre-integrated into the solid premix, continuously eliminating "harmful air bubbles" during subsequent mixing and pouring, further optimizing the internal structure of the product. In S2, the secondary mixing of the premix and premixed liquid ensures full integration of the components. Combined with the synergistic effect of the raw materials themselves, this guarantees that the product's strength, water resistance, and frost resistance meet stable standards. The 28-day compressive strength meets the C30 concrete grade standard, and the softening coefficient is greater than 0.85.

[0028] Convenient and efficient operation, suitable for industrial production: The preparation process is simple and easy to control, requiring no complex equipment or special process conditions. The mixing of raw materials in S1 and the stirring and pouring in S2 can all be completed using conventional building material production equipment, lowering the production threshold. The initial fluidity of the mixture exceeds 120mm, enabling self-flowing and self-compacting. The pouring and molding process can be completed within 10 minutes, significantly improving construction efficiency. Combined with the rapid hardening characteristic of hemihydrate phosphogypsum, the specimens can be demolded after 24 hours, enabling rapid mold turnover, significantly shortening the production cycle, improving the production qualification rate and capacity, and adapting to the needs of large-scale industrial mass production.

[0029] Mild curing conditions reduce production energy consumption and costs: Utilizing indoor natural curing methods eliminates the need for additional energy inputs such as steam curing, reducing energy consumption and production costs. It also avoids potential damage to the internal structure of the product caused by high-temperature curing, ensuring the volume stability and durability of the curbstone. Natural curing achieves design performance requirements in just 28 days. The curing process does not require precise temperature and humidity control by specialized personnel, making operation simple and management costs low, further reducing overall labor and energy costs.

[0030] High raw material utilization rate and enhanced green environmental protection attributes: Through a scientific step-by-step mixing process, anhydrous phosphogypsum, granular yellow phosphorus slag, and other industrial solid waste raw materials are evenly dispersed in the system, avoiding slurry stratification or aggregate settling, ensuring that solid waste materials are fully utilized. The product contains up to 90% solid waste, achieving efficient resource utilization of industrial solid waste. The entire preparation process generates no additional pollutants, solving the environmental disposal problems of solid wastes such as phosphogypsum and phosphorus slag, and reducing dependence on non-renewable resources such as natural stone and sand, which aligns with the concept of green development and has both environmental and social benefits.

[0031] According to some embodiments of the present invention, the stirring time is 3-5 minutes.

[0032] According to some embodiments of the present invention, the pouring time is within 10 minutes.

[0033] The curb stones prepared using hemihydrate phosphogypsum as a pure cementing material are prone to early drying shrinkage and cracking. If traditional sand and gravel are used as aggregates, the prepared slurry is prone to stratification and aggregate settling, thus weakening the overall performance of the product. In addition, hemihydrate phosphogypsum hardens quickly and has strong thixotropy, which significantly reduces its initial fluidity, making it difficult to meet the requirements of industrial production.

[0034] Anhydrous phosphogypsum obtained through high-temperature calcination not only exhibits superior fluidity and water resistance compared to hemihydrate phosphogypsum, but also produces short columnar dihydrate gypsum crystals upon hydration, demonstrating better volume stability. Using anhydrous-hemihydrate phosphogypsum in conjunction with phosphate slag to prepare curbstones comprehensively leverages the excellent fluidity, water resistance, and post-hydration volume stability of anhydrous phosphogypsum, as well as the rapid hardening characteristic of hemihydrate phosphogypsum. This product ensures good initial fluidity while maintaining a short curing cycle, facilitating production operations and enabling rapid mold transfer, thereby improving production efficiency and quality while reducing labor costs. Furthermore, lightweight phosphate slag aggregate resists the drying shrinkage of cementitious materials and disperses evenly in the slurry, enhancing product stability and uniformity; simultaneously, using solid waste phosphate slag as aggregate significantly reduces material costs. Attached Figure Description

[0035] Figure 1 This is a physical sample of the curbstone from Example 1. Detailed Implementation

[0036] The following will describe the concept and technical effects of the present invention clearly and completely with reference to embodiments, so as to fully understand the purpose, features and effects of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are all within the scope of protection of the present invention.

[0037] In the description of this invention, the terms "one embodiment," "some embodiments," "illustrative embodiment," "example," "specific example," or "some examples," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0038] Unless otherwise specified, "room temperature" in this invention means 25℃±5℃.

[0039] Unless otherwise specified, "about" in this invention means that the allowable error is within ±2%.

[0040] Unless otherwise specified in the examples, the procedures should be performed under standard conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0041] In the example: Anhydrous phosphogypsum is made by firing raw phosphogypsum at 800℃ for 2 hours.

[0042] The hemihydrate phosphogypsum was fired at 150℃ for 2 hours.

[0043] The anhydrous phosphogypsum comes from Guizhou Phosphate (Group) Co., Ltd.

[0044] The hemihydrate phosphogypsum comes from Guizhou Phosphate (Group) Co., Ltd.

[0045] The gypsum modifier was purchased from Hunan Tieke Track Technology Co., Ltd.

[0046] The silicate cement was PO.42.5 grade cement, purchased from Anhui Conch Cement Co., Ltd.

[0047] The fineness modulus of the granular yellow phosphorus slag is 3.5-3.8, and it was purchased from Guizhou Phosphate (Group) Co., Ltd.

[0048] The water-reducing agent is a polycarboxylate water-reducing agent, purchased from Bernuo New Materials (Beijing) Technology Co., Ltd.

[0049] The defoamer is an organosilicon defoamer, purchased from Dongguan Defeng Defoamer Co., Ltd.

[0050] Example 1 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 339 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 77 parts silicate cement, 385 parts granular yellow phosphorus slag, 3 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0051] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone. Figure 1 As shown.

[0052] Example 2 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 339 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 154 parts silicate cement, 308 parts granular yellow phosphorus slag, 3 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0053] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0054] Example 3 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 339 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 231 parts silicate cement, 231 parts granular yellow phosphorus slag, 3 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0055] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0056] Example 4 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 231 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 77 parts silicate cement, 493 parts granular yellow phosphorus slag, 3 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0057] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0058] Example 5 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 231 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 154 parts silicate cement, 416 parts granular yellow phosphorus slag, 3 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0059] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0060] Example 6 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 231 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 231 parts silicate cement, 339 parts granular yellow phosphorus slag, 3 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0061] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0062] Example 7 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 154 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 77 parts silicate cement, 570 parts granular yellow phosphorus slag, 2 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0063] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0064] Example 8 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 185 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 154 parts silicate cement, 462 parts granular yellow phosphorus slag, 2 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0065] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0066] Example 9 A high-durability anhydrous-hemihydrate phosphogypsum slag curbstone, the raw material of which is composed of the following components in parts by weight: 632 parts anhydrous phosphogypsum, 185 parts hemihydrate phosphogypsum, 108 parts gypsum modifier, 231 parts silicate cement, 385 parts granular yellow phosphorus slag, 2 parts polycarboxylate superplasticizer, 1 part defoamer, and 462 parts water.

[0067] The specific preparation method includes the following steps: (1) After weighing anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, lime powder and defoamer, mix them evenly in proportion, pour them into a mixer and dry mix for 1-2 minutes to ensure that the materials are fully mixed to obtain premixed material. (2) Add the weighed water-reducing agent to the water and stir thoroughly to ensure that the water-reducing agent is fully dissolved to obtain a premixed liquid; then pour the premixed liquid into the mixer of the premixed material and stir at a stirring speed of 165r / min for 3-5min to obtain a mixture; (3) The obtained mixture is loaded into the mold. The mixture can flow and compact itself. The casting process needs to be completed within 10 minutes. The specimen hardens and is demolded after 24 hours. (4) After demolding, the specimen is naturally cured for 28 days to obtain the curbstone.

[0068] Comparative Example 1 The curbstone was prepared according to the method in Example 1 of CN109734404A.

[0069] Comparative Example 2 The curbstone was prepared according to the method in Example 1 of CN114685134A.

[0070] Performance testing The curb stones obtained in Examples 1 to 9 were tested for initial flowability, compressive strength, water absorption, softening coefficient and freeze-thaw resistance at the corresponding ages.

[0071] The testing was conducted in accordance with the standards "Concrete Curbstone" (JC / T 899-2016) and "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081-2019).

[0072] The results are shown in Table 1.

[0073] Table 1

[0074] In the curb stones prepared in Examples 1-9, solid waste materials such as phosphogypsum and phosphate slag account for as much as 90%, which can realize the large-scale disposal of industrial solid waste. Performance test results from each example show that the product exhibits excellent overall performance: the initial flowability exceeds 120 mm, and the 1-day compressive strength reaches over 5 MPa. This not only meets the flowability requirements of the production casting process but also ensures that the product does not break during demolding after 24 hours, significantly improving the production qualification rate.

[0075] Further performance testing showed that the 28-day compressive strength of the curb stones in Examples 1-9 all reached the C30 concrete grade standard, and the water absorption rate was stably controlled below 6%. After 25 freeze-thaw cycles, the mass loss was less than 2% and the strength loss was less than 20%, fully meeting the requirements for strength, water absorption, and freeze-thaw resistance in the JC / T 899-2016 "Concrete Curb Stone" standard. Furthermore, the product's 28-day softening coefficient is greater than 0.85, effectively improving the shortcomings of traditional gypsum-based materials in terms of poor water resistance, making it suitable for use in humid environments. In terms of cost control, the material cost can be reduced to approximately 12.66 yuan / m², giving it a significant price competitive advantage.

[0076] Compared to the comparative cases, this invention makes extensive use of anhydrous phosphogypsum calcined at 800~1200℃, which, after hydration, forms short columnar dihydrate gypsum crystals with better volume stability, resulting in superior water resistance. Simultaneously, the use of solid waste phosphogypsum slag resists the drying shrinkage of cementitious materials and ensures uniform dispersion in the slurry, improving product stability and uniformity while reducing material costs.

[0077] Overall, the curbstone of this invention is not only easy to construct and has reliable strength, but also has excellent water resistance and frost resistance. At the same time, it achieves a double reduction in labor and material costs, and has broad market application prospects.

[0078] It should be noted that high single strength does not necessarily mean that the product is suitable for actual production and has good overall performance. The advantages of this invention lie in its excellent working performance, water resistance and cost advantage, which fully meet the requirements of the specifications.

[0079] The present invention has been described in detail above with reference to the embodiments. However, the present invention is not limited to the above embodiments. Within the scope of knowledge possessed by those skilled in the art, various changes can be made without departing from the spirit of the present invention.

Claims

1. A highly durable anhydrous-hemihydrate phosphogypsum slag curbstone, characterized in that, The raw materials for preparation, by weight, include: Anhydrous phosphogypsum: 600-700 parts Hemihydrate phosphogypsum: 100-350 parts Gypsum modifier: 60-120 parts, Silicate cement: 60-250 parts Granular yellow phosphorus slag: 200-600 parts Polycarboxylate superplasticizer: 1-5 parts Defoamer: 1-5 parts Water: 300-500 servings.

2. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1, characterized in that, The raw materials for preparation, by weight, include: Anhydrous phosphogypsum 616-693 parts, 154-339 parts of hemihydrate phosphogypsum 77-108 parts of gypsum modifier, Portland cement 77-231 parts, 231-570 parts of granular yellow phosphorus slag 2-3 parts of polycarboxylate superplasticizer 1-2 parts of defoamer 462-493 portions of water.

3. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1 or 2, characterized in that, The anhydrous phosphogypsum is produced by firing raw phosphogypsum at a high temperature of 800~1200℃.

4. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1 or 2, characterized in that, The hemihydrate phosphogypsum is fired at a high temperature of 150~300℃.

5. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1 or 2, characterized in that, The silicate cement is type PO.42.5 cement.

6. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1 or 2, characterized in that, The fineness modulus of the granular yellow phosphorus slag is 3-4.

7. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 6, characterized in that, The fineness modulus of the granular yellow phosphorus slag is 3.1-3.

8.

8. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1 or 2, characterized in that, The water reduction rate of the polycarboxylate superplasticizer is 30-40%.

9. The high-durability anhydrous-hemihydrate phosphogypsum slag curbstone according to claim 1 or 2, characterized in that, The defoamer is an organosilicon defoamer.

10. A method for preparing high-durability anhydrous-hemihydrate phosphogypsum slag curb stones as described in any one of claims 1 to 9, characterized in that, Includes the following steps: S1: Mix the anhydrous phosphogypsum, hemihydrate phosphogypsum, gypsum modifier, silicate cement, granular yellow phosphorus slag, and defoamer in proportion to obtain a premix; add the polycarboxylate superplasticizer to water and stir evenly to obtain a premix liquid. S2: The premixed material and premixed liquid are stirred and treated, poured into molds, and then naturally cured indoors. After demolding, the high-durability anhydrous-semi-hydrated phosphogypsum slag curbstone is obtained.

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