A roadblock ball based on phosphogypsum-based composite cementitious material and a preparation method thereof

Abstract

This application relates to the field of road traffic facility technology, specifically disclosing a road barrier ball based on a phosphogypsum-based composite cementitious material and its preparation method. The road barrier ball is obtained by mixing the following components with water and then casting them into shape: 60-80 parts of type II anhydrous gypsum, 15-35 parts of building gypsum powder, 2-8 parts of ordinary silicate cement, 0.5-2 parts of potassium sulfate, 0.05-0.3 parts of protein retarder, and 0.2-0.5 parts of polycarboxylate superplasticizer. The type II anhydrous gypsum is obtained from phosphogypsum through reverse flotation and calcination at 700-850℃, with a total phosphorus content ≤0.8%. This invention is the first to successfully use a phosphogypsum-based cementitious material in the preparation of road barrier balls, realizing the high-value utilization of solid waste. The prepared road barrier ball has a 28-day compressive strength ≥40MPa, a softening coefficient ≥0.85, and a density of 1.8-2.0 g / cm³. 3 It is more than 20% lighter than concrete, and is weather-resistant, impact-resistant, and has a dense surface. It can be made into solid or hollow structures, and road-blocking stones can be widely used in parking lots, pedestrian streets and other places.

Description

Technical Field

[0001] This invention relates to the field of road traffic facility technology, specifically to a road barrier ball based on phosphogypsum-based composite cementitious material and its preparation method. Background Technology

[0002] Roadblock stones, also known as bollards, barrier stones, or vehicle barriers, are widely used in parking lots, pedestrian streets, squares, residential entrances, parks, and other places to isolate vehicles, guide traffic, protect pedestrians, and beautify the environment. Traditional roadblock stones are mainly classified into three categories based on their material: concrete stones, natural stone stones, and plastic stones.

[0003] Concrete stone balls are made of ordinary silicate cement as cementing material and sand and gravel aggregate. They are the most common roadblock stones on the market. For example, patent CN111377678B discloses a fiber-reinforced recycled high-performance concrete self-luminous roadblock, which is divided into two parts, inner and outer. The inner part is steel fiber-reinforced recycled concrete, and the outer part is a polymer waterproof mortar protective layer with added energy storage luminescent material. It has the following defects: (1) heavy weight. The weight of a solid concrete ball with a diameter of 40-60cm can reach 200-500kg. It is extremely difficult to transport, install and move, and mechanical equipment is required; (2) high energy consumption in production. The carbon emissions of cement production are large and do not meet the requirements of green environmental protection; (3) rough surface, easy to attract dust, poor aesthetics; (4) easy to crack and weather when used outdoors for a long time, and high maintenance cost. Natural stone balls are carved or polished from natural stones such as granite and marble. They have the advantages of good texture and strong decorative properties, but they have the following problems: (1) Limited resources, high mining and processing costs, and expensive prices; (2) Heavy weight, comparable to concrete stone balls, making transportation and installation difficult; (3) A large amount of dust is generated during processing, causing serious environmental pollution. Plastic or fiberglass stone balls are made from polyethylene, glass fiber reinforced plastic, etc. They are lightweight and easy to handle, but they have the following defects: (1) Poor weather resistance, easily aged, discolored, and brittle due to sun and rain exposure; (2) Weak impact resistance, easily damaged by vehicle impacts; (3) Difficult to degrade after disposal, causing secondary pollution.

[0004] Phosphogypsum is an industrial byproduct generated during the wet-process phosphoric acid production process. Large-scale stockpiling of phosphogypsum not only occupies land resources but also causes serious environmental problems. There are reports of using phosphogypsum to prepare building gypsum or type II anhydrous gypsum through calcination for the production of building materials such as wall materials and mortar. However, there are no reports in the existing technology of using phosphogypsum-based cementitious materials to prepare roadside bollards. This is mainly because ordinary gypsum products have three major technical bottlenecks: (1) poor water resistance, softening and disintegrating upon contact with water, making them unsuitable for outdoor use; (2) insufficient strength, making it difficult to withstand vehicle impacts and long-term loads; and (3) easy surface powdering, affecting aesthetics and service life. Therefore, despite the wide availability and low cost of phosphogypsum, its application in the field of roadside bollards has remained unexplored.

[0005] Therefore, there is an urgent need to address the technological gap in the preparation of roadblocks by introducing phosphogypsum-based composite cementitious materials into the preparation of roadblocks, and to fill the performance shortcomings of existing roadblocks, in order to fill this technological gap. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention provides a road-blocking stone ball based on phosphogypsum-based composite cementitious material and its preparation method, thereby solving the following problems in existing technologies: 1. Traditional concrete or stone road-blocking stone balls are heavy and difficult to transport and install; 2. Ordinary gypsum products have low strength, poor water resistance, and cannot be used outdoors; 3. Plastic stone balls have poor weather resistance, weak impact resistance, and are prone to aging; 4. The high-value utilization of industrial by-product phosphogypsum.

[0007] To address the aforementioned problems, this invention provides a bollard based on a phosphogypsum-based composite cementitious material. The bollard is formed by mixing the following dry materials (in parts by weight) with water and then casting: Type II anhydrous gypsum: 60-80 parts; building gypsum powder: 15-35 parts; ordinary silicate cement: 2-8 parts; potassium sulfate: 0.5-2 parts; protein-based retarder: 0.05-0.3 parts; polycarboxylate superplasticizer: 0.2-0.5 parts; wherein the mass ratio of water to dry materials is 0.25-0.32.

[0008] Furthermore, the type II anhydrous gypsum is obtained by calcining wet-process phosphoric acid by-product phosphogypsum at 700-850℃ after reverse flotation pretreatment. Its anhydrous gypsum content is ≥80%, fineness is 200-400 mesh, pH value is 8-10, and total phosphorus content is ≤0.8%.

[0009] Furthermore, by weight, the type II anhydrous gypsum comprises 65-75 parts, the building gypsum powder comprises 20-30 parts, and the ordinary silicate cement comprises 4-6 parts.

[0010] Furthermore, the type II anhydrous gypsum comprises 70 parts, the building gypsum powder comprises 25 parts, and the ordinary silicate cement comprises 5 parts.

[0011] Further, the potassium sulfate is 0.8-1.2 parts by mass; the polycarboxylate superplasticizer is a powdered polycarboxylate superplasticizer, which is 0.25-0.35 parts by mass; and the protein retarder is a protein-based gypsum-specific retarder.

[0012] On the other hand, the present invention also provides a method for preparing road-blocking stones based on phosphogypsum-based composite cementitious materials, comprising the following steps: S1. Preparation of dry mix: Type II anhydrous gypsum, building gypsum powder, ordinary silicate cement, potassium sulfate, protein retarder and polycarboxylate superplasticizer are dry mixed evenly according to the proportion to obtain composite cementitious material dry mix; S2. Add water and stir: Mix the dry mixture obtained in S1 with water and stir to obtain a uniform slurry; S3. Casting and demolding: The slurry obtained in S2 is poured into a spherical mold, vibrated to compact it, and then demolded after static curing to obtain the stone ball blank. S4. Natural curing: The stone ball blanks obtained in S3 are naturally cured to the specified age to obtain the road-blocking stone balls.

[0013] Further, in S2, the dry mix is ​​mixed with water at a water-to-binder ratio of 0.25-0.32, and the stirring time is 2-3 minutes; in S3, the static curing time is 4-8 hours.

[0014] Furthermore, in S3, when the ambient temperature is above 25℃, the static curing time is 4 hours; when the ambient temperature is below 10℃, the static curing time is 6 hours.

[0015] Furthermore, in S3, the spherical mold is a split mold with a release agent coated on the inner wall, and the diameter of the sphere is 20-50cm; when the road-blocking stone ball is a hollow structure, the spherical mold has a detachable spherical core mold inside, and the core mold is removed after molding to form a cavity.

[0016] Furthermore, step S5, coating, is included after S4: coating the surface of the bollard with a transparent, waterproof, and wear-resistant coating or a colored paint.

[0017] Compared with the prior art, the present invention has the following significant advantages: 1. Filling a technological gap: This invention is the first to use phosphogypsum-based composite cementitious material in the preparation of roadside bollards, and has successfully developed phosphogypsum-based roadside bollards that can be used outdoors, filling a gap in this technological field.

[0018] 2. Lightweight and high strength: The density of the stone spheres of this invention is approximately 1.8-2.0 g / cm³. 3 It is lower than 2.4 g / cm³ of concrete. 3 It reduces weight by about 20%, making it easier to transport and install; its 28-day compressive strength is ≥40MPa, and its impact resistance is excellent, meeting the requirements for roadblock use.

[0019] 3. Excellent weather resistance: softening coefficient ≥0.85. After 25 freeze-thaw cycles, the appearance remains intact without cracks, and it can be used outdoors for a long time, overcoming the defect of ordinary gypsum products softening when exposed to water.

[0020] 4. Dense and wear-resistant surface: The introduction of cement components makes the surface of the stone ball highly hard. No powder falls off when scratched with a fingernail, and it is not easy to generate dust. It can be made into imitation stone or colored effects, which are beautiful and durable.

[0021] 5. Adjustable setting time: By adjusting the dosage of protein retarder, the initial setting time of the slurry can be flexibly adjusted within the range of 30-90 minutes to adapt to different seasons and process requirements.

[0022] 6. Environmental protection and energy saving: The main raw material is industrial by-product phosphogypsum, realizing the high-value utilization of solid waste. The production energy consumption is far lower than that of cement products, which meets the requirements of green and low-carbon.

[0023] 7. High design flexibility: Different colors and textures can be obtained by adjusting pigments or surface coatings, and hollow spheres can also be made to further reduce weight. Attached Figure Description

[0024] Figure 1 This is a process flow diagram of the preparation method of the present invention. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0026] The raw material components used in the embodiments of the present invention are as follows: Phosphogypsum: Phosphogypsum, a byproduct of wet-process phosphoric acid production, comes from a chemical company. After reverse flotation pretreatment, the total phosphorus content is 0.6-0.8%, and the free water content is ≤15%.

[0027] Type II anhydrous gypsum: The above phosphogypsum was calcined at 750℃ for 30 minutes, naturally cooled, and pulverized to 325 mesh. The anhydrous gypsum content was measured to be 83%, pH value was 9, and total phosphorus content was 0.7%.

[0028] Building gypsum powder: Commercially available β-type hemihydrate gypsum, fineness 200 mesh, initial setting time 6 minutes, final setting time 15 minutes, conforming to GB / T 9776-2008 standard.

[0029] Ordinary Portland cement: PO 42.5 grade, conforming to GB 175-2007 standard.

[0030] Potassium sulfate: Industrial grade, purity ≥98%, fineness 200 mesh.

[0031] Protein-based retarder: Commercially available protein-based gypsum retarder, in powder form, appears as a pale yellow powder.

[0032] Polycarboxylate superplasticizer: Powdered polycarboxylate superplasticizer with a water reduction rate of ≥25%, conforming to GB 8076-2008 standard.

[0033] Water: tap water or clean industrial water.

[0034] Example 1: In this example, the obstacle stone ball is a solid ball. S1. Preparation of dry mix: Take 70 parts of type II anhydrous gypsum, 25 parts of building gypsum powder, 5 parts of ordinary silicate cement, 1 part of potassium sulfate, 0.1 parts of protein retarder, and 0.3 parts of polycarboxylate superplasticizer, and dry mix for 5 minutes to obtain composite cementitious material dry mix. S2. Add water and mix: Mix the dry mixture with water at a water-to-binder ratio of 0.28 and mix for 2 minutes using a planetary mixer to obtain a uniform slurry; S3. Casting and Demolding: Pour the slurry into a split spherical mold with a diameter of 40cm. Coat the inner wall of the spherical mold with a release agent. Place it on a vibrating table and vibrate for 30 seconds to compact it. Then let it stand for curing. Demold after 4 hours at an ambient temperature of 28℃ in summer and after 6 hours at an ambient temperature of 5℃ in winter to obtain a solid stone ball blank. S4. Natural curing: Place the stone ball blank in natural indoor conditions, with a temperature of 20±5℃ and a relative humidity of 60±10%, and cure for 28 days to obtain the road-blocking stone ball.

[0035] Example 2: In this example, the road-blocking stone ball is a hollow ball. The difference between this embodiment and embodiment 1 is that in S3, the mold has a built-in detachable spherical core mold with a diameter of 20cm. After molding, the core mold is removed to form a hollow structure with a wall thickness of 10cm.

[0036] Example 3: Cement High Limit The difference between this embodiment and Embodiment 1 is that in S1, there are 8 parts of ordinary silicate cement and 22 parts of building gypsum powder.

[0037] Example 4: Adding pigments The difference between this embodiment and embodiment 1 is that in S3, iron oxide red pigment is added to the slurry, the iron oxide red pigment accounts for 1% of the slurry mass, and after stirring evenly, it is poured to obtain red stone balls.

[0038] Comparative Example 1: No cement The difference between this comparative example and Example 1 is that in S1, ordinary silicate cement is not added, and the amount of building gypsum powder is 30 parts.

[0039] Comparative Example 2: No activator The difference between this comparative example and Example 1 is that potassium sulfate is not added in S1.

[0040] Comparative Example 3: No retarder The difference between this comparative example and Example 1 is that no protein retarder is added in S1.

[0041] Comparative Example 4: Single System of Building Plaster The difference between this comparative example and Example 1 is that in S1, only 100 parts of building gypsum powder are used; in S2, the water-cement ratio is 0.50.

[0042] Comparative Example 5: Ordinary concrete stone spheres Commercially available C30 concrete solid stone ball, approximately 40cm in diameter.

[0043] Performance testing: The stone spheres or standard specimens prepared in the embodiments and comparative examples of this invention were tested using the following methods: 1. Setting time: Tested according to GB / T 17669.4-1999 "Determination of physical properties of building gypsum paste".

[0044] 2. Compressive strength: Tested according to GB / T 17669.3-1999 "Determination of mechanical properties of building gypsum", with specimen size of 40mm×40mm×160mm and curing period of 28 days.

[0045] 3. Softening coefficient: After curing the specimen for 28 days, the ratio of the compressive strength under saturated water absorption state to the compressive strength under dry state is determined.

[0046] 4. Freeze-thaw cycle: The slow freezing method was carried out in accordance with GB / T 50082-2009 "Standard for Test Methods of Long-term Performance and Durability of Ordinary Concrete". 25 freeze-thaw cycles were performed, and the appearance changes were observed and the strength loss was measured.

[0047] 5. Bulk density: The ratio of mass to volume of the weighed specimen. For solid spheres, the density is calculated directly. For hollow spheres, the apparent density is calculated based on the total volume (including the cavity).

[0048] 6. Impact resistance: Place the stone ball (40cm in diameter) on a flat surface and drop a 10kg sandbag from a height of 1m to strike the surface of the ball. Observe whether it cracks.

[0049] The performance test results are shown in the table below: Table 1 Performance test results of the examples and comparative examples Group 28-day compressive strength (MPa) Softening coefficient Appearance after 25 freeze-thaw cycles <![CDATA[Density (g / cm 3 )]]> Impact resistance (10kg·1m) Example 1 43.1 0.88 Complete and without cracks 1.85 No cracks Example 2 42.5 0.87 Complete and without cracks 1.20 No cracks Example 3 44.0 0.90 Complete and without cracks 1.90 No cracks Example 4 43.0 0.88 Complete and without cracks 1.85 No cracks Comparative Example 1 41.3 0.82 Surface microcracks 1.80 microcracks Comparative Example 2 25.8 0.65 Severe cracking 1.70 cracking Comparative Example 3 40.5 0.86 Complete and without cracks 1.85 No cracks Comparative Example 4 15.5 0.35 Disintegration 1.50 Severe cracking Comparative Example 5 35.0 0.90 Complete and without cracks 2.40 No cracks Results Analysis 1. Filling a technological gap and achieving the first application of phosphogypsum in the field of bollards: Comparative Example 4 shows that the single-system building gypsum has low strength, poor water resistance, and weak impact resistance, making it completely unsuitable for use as bollards; Comparative Example 5 shows that while concrete bollards meet performance requirements, they are heavy. Example 1 of this invention uses a phosphogypsum-based ternary composite cementitious material in the preparation of bollards, achieving or exceeding the performance of concrete bollards in terms of strength, weather resistance, and impact resistance, while reducing weight by approximately 23%, successfully filling the technological gap in the application of phosphogypsum in the field of bollards.

[0050] 2. The key role of cement in weather resistance: Comparative Example 1 had a softening coefficient of 0.82 without cement, and microcracks appeared after freeze-thaw, resulting in a decrease in impact resistance; Example 1 had a softening coefficient of 0.88, and remained intact after freeze-thaw, indicating that cement significantly improved water resistance and freeze resistance.

[0051] 3. Significant advantages of being lightweight and high-strength: Example 1 density 1.85 g / cm³ 3 Comparison Example 5: Concrete 2.40 g / cm³ 3 It is about 23% lighter, but its compressive strength of 43.1 MPa is higher than that of the comparative 5C30 concrete (35 MPa), achieving a balance between lightweight and high strength.

[0052] 4. Necessity of activator: Comparative Example 2 does not contain potassium sulfate, has extremely slow solidification, low strength, and severe cracking after freeze-thaw cycles, which cannot meet the requirements for use.

[0053] 5. Advantages of hollow structure: Example 2 is a hollow sphere with a density of only 1.20 g / cm³. 3 It is 35% lighter than a solid ball, making it easier to handle, while maintaining excellent strength and weather resistance, making it suitable for weight-sensitive applications.

[0054] 6. Decorative effect: Example 4 obtains a uniform red color by adding pigments, and the surface can be further coated to meet personalized needs.

[0055] 7. Industrial Application Description: The bollards and their preparation method provided by this invention primarily utilize industrial by-product phosphogypsum as raw material, achieving high-value utilization of solid waste and aligning with national circular economy and green building materials policies. The production process is simple, requiring no high-temperature or high-pressure curing; natural curing at room temperature is sufficient. Equipment investment is low, making it suitable for large-scale production. The products can be widely used for vehicle isolation and pedestrian protection in parking lots, pedestrian streets, squares, residential entrances, parks, and other locations, offering significant economic and social benefits.

[0056] In summary, this invention is the first to successfully apply phosphogypsum-based composite cementitious material to the preparation of roadside bollards. The product has the advantages of being lightweight, high-strength, weather-resistant, and impact-resistant, and can replace traditional concrete and plastic bollards, thus having broad market promotion value.

[0057] The above descriptions are merely embodiments of the present invention, and common knowledge regarding specific structures and characteristics is not elaborated upon here. It should be noted that those skilled in the art can make various modifications and improvements without departing from the structure of the present invention, and these should also be considered within the scope of protection of the present invention. These modifications and improvements will not affect the effectiveness of the present invention or the practicality of the patent. The scope of protection claimed in this application should be determined by the content of its claims, and the specific embodiments described in the specification can be used to interpret the content of the claims.

Claims

1. A bollard based on phosphogypsum-based composite cementitious material, characterized in that: The road-blocking stone balls are made by mixing the following dry materials with water and then casting them into shape: Type II anhydrous gypsum: 60-80 parts; building gypsum powder: 15-35 parts; ordinary silicate cement: 2-8 parts; Potassium sulfate: 0.5-2 parts; protein retarder: 0.05-0.3 parts; polycarboxylate superplasticizer: 0.2-0.5 parts; wherein the mass ratio of water to dry material is 0.25-0.

32.

2. The bollard based on phosphogypsum-based composite cementitious material according to claim 1, characterized in that: The type II anhydrous gypsum is obtained by calcining wet-process phosphoric acid by-product phosphogypsum at 700-850℃ after reverse flotation pretreatment. Its anhydrous gypsum content is ≥80%, fineness is 200-400 mesh, pH value is 8-10, and total phosphorus content is ≤0.8%.

3. The bollard based on phosphogypsum-based composite cementitious material according to claim 1, characterized in that: By weight, the type II anhydrous gypsum comprises 65-75 parts, the building gypsum powder comprises 20-30 parts, and the ordinary silicate cement comprises 4-6 parts.

4. A bollard based on phosphogypsum-based composite cementitious material according to claim 3, characterized in that: The type II anhydrous gypsum comprises 70 parts, the building gypsum powder comprises 25 parts, and the ordinary silicate cement comprises 5 parts.

5. A bollard based on phosphogypsum-based composite cementitious material according to claim 1, characterized in that: The potassium sulfate is present in an amount of 0.8-1.2 parts by mass; the polycarboxylate superplasticizer is a powdered polycarboxylate superplasticizer, and its mass is 0.25-0.35 parts by mass; the protein retarder is a protein-based gypsum-specific retarder.

6. A method for preparing the road-blocking stone ball according to any one of claims 1-5, characterized in that: Includes the following steps: S1. Preparation of dry mix: Type II anhydrous gypsum, building gypsum powder, ordinary silicate cement, potassium sulfate, protein retarder and polycarboxylate superplasticizer are dry mixed evenly according to the proportion to obtain composite cementitious material dry mix; S2. Add water and stir: Mix the dry mixture obtained in S1 with water and stir to obtain a uniform slurry; S3. Casting and demolding: The slurry obtained in S2 is poured into a spherical mold, vibrated to compact it, and then demolded after static curing to obtain the stone ball blank. S4. Natural curing: The stone ball blanks obtained in S3 are naturally cured to the specified age to obtain the road-blocking stone balls.

7. The preparation method according to claim 6, characterized in that: In S2, the dry mix is ​​mixed with water at a water-to-binder ratio of 0.25-0.32, and the stirring time is 2-3 minutes; in S3, the static curing time is 4-8 hours.

8. The preparation method according to claim 7, characterized in that: In S3, when the ambient temperature is above 25℃, the static curing time is 4 hours; when the ambient temperature is below 10℃, the static curing time is 6 hours.

9. The preparation method according to claim 6, characterized in that: In S3, the spherical mold is a split mold with a release agent on the inner wall, and the diameter of the sphere is 20-50cm. When the road-blocking stone ball is a hollow structure, the spherical mold has a detachable spherical core mold inside, and the core mold is removed after molding to form a cavity.

10. The preparation method according to claim 6, characterized in that: The process after S4 includes step S5: coating a transparent, waterproof, and wear-resistant coating or colored paint onto the surface of the bollard.

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