Magnesium phosphate cement inorganic gel material steel bridge deck pavement structure and preparation method

Abstract

The invention discloses a magnesium phosphate cement inorganic gel material steel bridge deck pavement structure and a preparation method thereof. The pavement structure comprises a steel bridge deck slab, a waterproof bonding layer, a magnesium phosphate cement concrete layer and a wear-resistant anti-skid layer, the surface of the steel bridge deck is subjected to shot blasting treatment; the waterproof bonding layer is coated with epoxy resin to form a continuous and uniform film layer; the magnesium phosphate cement concrete layer is formed by pouring a magnesium phosphate cementing material generated by reaction of dead burned magnesium oxide and ammonium dihydrogen phosphate with fly ash, borax, a polycarboxylate superplasticizer, steel fibers and selected graded quartz sand, and inducing cracks are formed in the magnesium phosphate cement concrete layer to control crack development; the wear-resistant anti-skid layer is a thin-layer wear-resistant coating or an asphalt concrete wearing layer and is fixed through the bonding layer. The preparation method comprises the steps of base surface treatment, waterproof bonding layer construction, magnesium phosphate cement concrete pouring, maintenance and surface treatment. Traditional mechanical anchoring such as studs is omitted, high-strength and durable interface connection is formed by means of chemical compatibility of materials, and the fatigue life is prolonged.

Description

Technical Field

[0001] This invention belongs to the field of bridge deck paving and structural reinforcement technology, specifically relating to a steel bridge deck paving structure and preparation method using magnesium phosphate cement inorganic gel material. Background Technology

[0002] Steel bridge deck paving technology is a crucial aspect of bridge engineering, and its quality directly affects the bridge's performance, safety, and durability. Currently, there are two main types of common steel bridge deck paving technologies: epoxy asphalt mixture paving and ultra-high performance concrete (UHPC) paving.

[0003] Epoxy asphalt pavement technology, as used in the Minpu Bridge project, primarily relies on epoxy asphalt as a bonding material to form a multi-layered pavement structure. This structure utilizes the excellent high-temperature stability and fatigue resistance of epoxy asphalt, and through a special mixture design, the pavement layers can adapt to the deformation requirements of the steel bridge deck. However, this pavement method has significant drawbacks: epoxy asphalt requires extremely high precision in construction processes, necessitating precise control of temperature and time parameters; the material's toughness is relatively insufficient, making it prone to cracking under heavy traffic and extreme temperature conditions; and repair is difficult, as localized repairs are often insufficient, requiring complete renovation.

[0004] Ultra-high performance concrete (UHPC) pavement is a new pavement technology that has emerged in recent years. Conventional steel-UHPC composite structures typically use densely packed shear keys (such as studs) to achieve interlayer connections, for example, by welding numerous studs onto the steel bridge deck and then placing a dense mesh of reinforcing steel in the UHPC layer. This structure does indeed improve the local stiffness of the bridge deck system and has a positive effect on extending the fatigue life of the pavement and the steel bridge deck. However, this traditional connection method has significant problems: the densely arranged shear keys not only cause inconvenience in the construction of the UHPC pavement layer but also greatly increase the difficulty of maintenance and repair during subsequent use. At the same time, because the plasticity of UHPC is generally lower than that of ordinary concrete, the dense steel mesh greatly increases the construction difficulty and may result in incomplete compaction, seriously affecting the forming quality of the UHPC layer, especially thin-layer UHPC layers.

[0005] In existing technologies, some improved UHPC pavement structures attempt to optimize construction by setting expansion joints and reducing the amount of steel reinforcement, such as the ultra-high performance concrete steel bridge deck pavement structure proposed in Chinese patent publication number CN108589518A. This structure divides the pavement layer into several segments by setting expansion joints extending along the width direction of the steel bridge deck inside the ultra-high performance concrete layer, and reduces the number of shear keys. However, this improvement still does not completely eliminate mechanical connection methods such as studs, and the construction process remains relatively complex.

[0006] For example, Chinese patent CN115142053A discloses a surface treatment method for steel bridge decks or steel structure components. This method uses a phosphate interface agent to treat the steel structure, utilizing the phosphating and electrochemical principles of dilute phosphoric acid with zinc oxide and zinc powder, combined with the acid-base reaction characteristics of the phosphate interface agent. This allows a phosphate layer to form on the steel plate before the phosphate interface agent is applied, and improves the interfacial bond strength between the steel plate and magnesium phosphate cement concrete. This significantly improves the bond strength between the magnesium phosphate cement concrete and the steel plate, enabling rapid construction of steel bridge deck paving and steel plate protection. It provides a new technical approach and guarantee for the effective use of magnesium phosphate cement concrete in steel bridge deck construction and steel structure protection. Although phosphate interface agents are heat-resistant, they are essentially rigid inorganic materials with insufficient flexibility. Under long-term fatigue loads, the brittle interface is more prone to microcracks and propagation, resulting in poor watertight protection performance and durability.

[0007] In summary, existing UHPC pavement technologies for steel bridge decks all rely on mechanical connection methods such as studs, leading to problems such as low construction efficiency, difficulty in quality control, and high long-term maintenance costs. Therefore, there is an urgent need to develop a new steel bridge deck pavement technology that can fundamentally simplify the interlayer connection structure, improve construction efficiency, and simultaneously ensure reliable connection and long-term performance between the pavement layer and the steel bridge deck. Summary of the Invention

[0008] In view of this, the purpose of this invention is to solve the above problems and provide a steel bridge deck pavement structure and preparation method using magnesium phosphate cement inorganic gel material.

[0009] To achieve the above objectives, the present invention provides the following technical solution: A steel bridge deck pavement structure made of magnesium phosphate cement inorganic gel material includes, from bottom to top, a steel bridge deck, a waterproof adhesive layer, a magnesium phosphate cement concrete layer, and a wear-resistant and anti-slip layer. The steel bridge deck serves as the base layer of the pavement structure; the waterproof adhesive layer is composed of a polymer material and is coated on the surface of the steel bridge deck; the magnesium phosphate cement concrete layer is poured on top of the waterproof adhesive layer; and the wear-resistant and anti-slip layer covers the magnesium phosphate cement concrete layer. This paving structure does not use mechanical anchoring. Instead, it directly utilizes the chemical compatibility between the magnesium phosphate cement concrete layer and the waterproof bonding layer to form a high-strength and durable interlayer bonding interface.

[0010] Furthermore, the wear-resistant and anti-slip layer is a thin-layer wear-resistant coating or an asphalt concrete wear layer, which is fixed to the magnesium phosphate cement concrete layer by an adhesive layer.

[0011] Furthermore, the waterproof adhesive layer is composed of epoxy resin material, with a coating amount of 0.8-1.2 kg / m². 2The thickness is 0.5-1.0 mm; the epoxy resin material has a bonding strength of not less than 5 MPa with the steel plate panel at 25℃, a bonding strength of not less than 2.5 MPa with the magnesium phosphate cement concrete layer, and an elongation of more than 30% to accommodate the deformation of the steel bridge deck.

[0012] Furthermore, the surface of the steel bridge deck is shot blasted to a cleanliness level of Sa2.5, and the surface roughness after rust removal is controlled within the range of 50-100μm to increase the mechanical bonding force with the waterproof adhesive layer.

[0013] Furthermore, the thickness of the magnesium phosphate cement concrete layer is 40-60mm, and the thickness is adjusted according to the bridge design requirements; induced joints are set in the magnesium phosphate cement concrete layer, the spacing of the induced joints is 1 / 4-1 / 6 of the slab length, and the depth is 1 / 3-1 / 2 of the pavement layer thickness; the crack resistance is improved by adding steel fiber reinforcement.

[0014] Furthermore, the magnesium phosphate cement concrete layer is cast from magnesium phosphate cementitious cement; the magnesium phosphate cementitious cement is made by mixing 45%-75% cementitious materials, 18%-28% mineral admixtures, 2%-7% retarder, 1%-5% dispersant, 1%-6% viscosity reducer, 3%-9% toughening materials and appropriate amount of aggregate by weight percentage. The gelling material is prepared by reacting calcined magnesium oxide and ammonium dihydrogen phosphate in a molar ratio of 3:1 with an acid-base neutralization reaction in the presence of water.

[0015] Furthermore, the recalcined magnesium oxide and ammonium dihydrogen phosphate are respectively ground to a specific surface area of ​​500-700 m². 2 / kg; the mass percentage content of magnesium oxide in the recalcined magnesium oxide is greater than 90%, and the mass percentage content of the active ingredient in the ammonium dihydrogen phosphate is greater than 98%.

[0016] Furthermore, the mineral admixture is fly ash, in which the mass percentage content of active SiO2 is 40%~50% and the mass percentage content of active Al2O3 is 30%~40%, which improves the fluidity of the slurry and reduces the heat of hydration. The retarder is borax, specifically borax decahydrate with a purity greater than 95%; the dispersant is a polycarboxylate-based high-efficiency water-reducing agent; the toughening material is steel fiber or carbon fiber, preferably 25mm steel fiber with a content of 2%; and the aggregate is selected graded quartz sand with a maximum particle size not exceeding 2.36mm.

[0017] A method for preparing a steel bridge deck pavement structure using magnesium phosphate cement inorganic gel material as described above includes the following steps: S1. Surface preparation: The top surface of the steel bridge deck is shot blasted to remove rust, achieving a cleanliness level of Sa2.5, thoroughly removing oxide scale and contaminants; the surface is cleaned with high-pressure air to ensure that there are no impurities on the surface that may affect adhesion; the steel bridge deck is preheated before applying the waterproof adhesive layer, with the temperature controlled at 40-60℃. S2. Waterproof Adhesive Layer Construction: Accurately prepare and thoroughly stir the epoxy resin material according to the specified ratio; apply the epoxy resin evenly to the surface of the steel bridge deck using a scraper or sprayer, controlling the coating amount to 0.8-1.2 kg / m². 2 The thickness is 0.5-1.0 mm, forming a continuous and uniform film layer to ensure no missed coating or accumulation; S3. Construction of Magnesium Phosphate Cement Concrete Layer: The subsequent pouring of magnesium phosphate cement concrete should be completed before the initial setting of the epoxy resin after the initial coating. A segmented pouring method should be adopted, with construction sections set according to the bridge structure. The magnesium phosphate cement concrete mixture should be evenly laid on top of the waterproof bonding layer, with a thickness of 40-60mm. Light vibration should be performed using a vibrating beam or plate vibrator to ensure the concrete is dense while avoiding damage to the waterproof bonding layer. The surface should be leveled using a screed to control the elevation and flatness of the pavement layer. Induction joints should be set within the pavement layer as needed, with a spacing of 1 / 4-1 / 6 of the slab length and a depth of 1 / 3-1 / 2 of the pavement layer thickness. S4. Curing process: Utilizing the self-curing properties of magnesium phosphate cement, no wet curing or heat curing measures are required; after pouring, cover the surface of the magnesium phosphate cement concrete layer with plastic film to prevent moisture from evaporating too quickly. S5. Surface treatment: Before the initial setting of magnesium phosphate cement concrete, the surface is roughened to increase the adhesion to the wear-resistant and anti-slip layer; the wear-resistant and anti-slip layer adopts a thin layer of wear-resistant coating or asphalt concrete wear layer. Before laying the wear-resistant and anti-slip layer, an adhesive layer is first laid on the magnesium phosphate cement concrete layer to fix the wear-resistant and anti-slip layer to the magnesium phosphate cement concrete layer.

[0018] Furthermore, the preparation process of the magnesium phosphate cement concrete includes: a) Place 45%-75% of the cementitious materials, 18%-28% of the mineral admixtures, 2%-7% of the retarder, 1%-5% of the dispersant, 1%-6% of the viscosity reducer, and 3%-9% of the toughening materials in a mixer according to the specified proportions and dry mix for 5-10 minutes to ensure uniform mixing. b) Gradually add 90% of the designed water volume to the dry mix, stir for 3-5 minutes, then add the remaining water and continue stirring for 2-3 minutes to form a uniform slurry; c) Add the selected graded quartz sand aggregate to the slurry and stir for 2-3 minutes to form a uniform concrete mixture; The dosage of retarder is adjusted according to the ambient temperature to control the setting time and ensure the operability of construction.

[0019] The beneficial effects of this invention are as follows: This invention utilizes magnesium phosphate cement concrete as the core material for the steel bridge deck pavement layer, combined with a waterproof bonding layer to achieve interlayer connections without mechanical anchoring. This is significantly superior to traditional epoxy asphalt or UHPC pavement technologies, achieving comprehensive breakthroughs in construction efficiency, structural durability, interlayer bonding performance, waterproofing and corrosion resistance, and overall economic and environmental benefits. Specific advantages are as follows: (1) Using magnesium phosphate cement concrete as the pavement layer material: Magnesium phosphate cement has excellent properties such as high early strength, strong bond strength with steel plates, and good volume stability. Its rapid hardening at room temperature without the need for heat (high temperature) curing significantly shortens the construction cycle. Magnesium phosphate cement generates magnesium phosphate gel through the acid-base neutralization reaction of recalcined magnesium oxide and ammonium dihydrogen phosphate. Its compressive strength can reach about 30 MPa in 2 hours, about 45 MPa in 1 day, and about 70 MPa in 28 days, which is far higher than the early performance of traditional silicate cement. This material does not require steam curing or wet curing, but only needs to be covered with plastic film for self-curing. Under ambient temperature above 20℃, light traffic can be opened 6-8 hours after pouring, and traffic can be fully opened after 24 hours. This rapid hardening characteristic greatly shortens the bridge closure time, and is particularly suitable for emergency reinforcement projects of municipal bridges, highway bridges or airport runways with high traffic volume and short maintenance windows. It avoids the traffic interruption and economic losses caused by traditional UHPC requiring several days of curing or epoxy asphalt requiring precise temperature control during construction. Meanwhile, magnesium phosphate cement exhibits excellent volume stability and low shrinkage. Combined with the toughening design of added steel fibers, it effectively limits the generation and development of early shrinkage cracks, improves crack resistance, and ensures the long-term integrity of the pavement layer under repeated vehicle loads and temperature changes.

[0020] (2) Elimination of traditional stud connection structure: By optimizing the magnesium phosphate cement formula, a long-term and durable connection can be achieved between it and the steel bridge deck through a waterproof adhesive layer, without any mechanical anchoring measures. At the same time, the surface bonding effectively disperses the stress concentration problem caused by local loads and vibrations on the bridge deck, which can effectively extend the fatigue life of the bridge deck. Traditional steel bridge deck UHPC pavement relies on dense stud welding to achieve shear force transfer, which not only increases the heat-affected zone of the steel plate and is prone to fatigue crack initiation, but also the studs obstruct the pouring, resulting in a high risk of non-compactness. Test data shows that the interface bonding strength is excellent in the early stage (pull-out strength of about 0.9 MPa after 2 hours, exceeding the tensile strength of the concrete matrix after 28 days), ensuring the synergistic work of the new and old layers, significantly reducing the risk of interlayer delamination and separation, and is suitable for long-term service in heavy traffic and extreme environments.

[0021] (3) Novel interlayer bonding system: Utilizing the chemical compatibility of magnesium phosphate cement and epoxy resin and other bonding materials, a high-strength and durable interlayer bonding interface is formed. Furthermore, the epoxy bonding layer itself can serve as a continuous waterproof barrier, enhancing the overall waterproof performance of the steel bridge. The alkaline cementitious system of magnesium phosphate cement and the polar groups of epoxy resin have good chemical compatibility, forming a dense and stable micro-interface transition zone, creating a "flexible transition layer" that can deform in tandem with the steel plate. This effectively absorbs and dissipates interfacial shear stress and peeling stress caused by temperature changes and vehicle loads, forming a dense water-sealing protection system and avoiding the interfacial voids and corrosion channels commonly found in traditional mechanical connections. The epoxy bonding layer coating amount is 0.8-1.2 kg / m². 2 With an elongation greater than 30%, it can accommodate the slight deformation of the steel bridge deck while providing a bond strength of not less than 5 MPa for the steel plate and not less than 2.5 MPa for the magnesium phosphate cement. This layer acts as a continuous waterproof barrier, effectively preventing the penetration of corrosive media such as moisture, chloride ions, and acid rain into the steel bridge deck, significantly improving the overall corrosion resistance of the steel bridge. Especially in marine environments, coastal bridges, or corrosive atmospheric conditions in industrial areas, the dense structure of magnesium phosphate cement further synergistically blocks corrosive media, extending the structural service life. Furthermore, this system is easy to construct, requiring no additional waterproof layer, thus reducing material and process costs.

[0022] Other advantages, objectives, and features of the invention will be set forth in part in the description which follows, and in part will be apparent to those skilled in the art from the following examination, or may be learned from practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0023] To make the objectives, technical solutions, and advantages of the present invention clearer, the preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings, wherein: Figure 1 This is a schematic diagram of the steel bridge deck paving structure made of magnesium phosphate cement inorganic gel material in an embodiment of the present invention. Detailed Implementation

[0024] The following specific examples illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. The present invention can also be implemented or applied through other different specific embodiments, and various details in this specification can be modified or changed based on different viewpoints and applications without departing from the spirit of the present invention. It should be noted that the illustrations provided in the following embodiments are only schematic representations of the basic concept of the present invention. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0025] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual pictures. They should not be construed as limiting the invention. To better illustrate the embodiments of the invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual product dimensions. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0026] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "front," and "rear" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present invention. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0027] Example 1 Please see Figure 1 This is a schematic diagram of a steel bridge deck paving structure made of magnesium phosphate cement inorganic gel material. The structure, from bottom to top, includes a steel bridge deck, a waterproof adhesive layer, a magnesium phosphate cement concrete layer, and a wear-resistant and anti-slip layer.

[0028] As the base layer of the pavement structure, the top surface of the steel bridge deck is shot blasted to Sa2.5 cleanliness level, and the surface roughness is controlled within the range of 50-100μm to enhance the mechanical bonding force with the waterproof adhesive layer.

[0029] The waterproof adhesive layer is composed of a high molecular polymer material, preferably epoxy resin, with a coating amount of 0.8-1.2 kg / m². 2 The thickness is 0.5-1.0 mm. This layer forms a continuous and uniform film with appropriate flexibility. At 25℃, the bond strength with the steel bridge deck is not less than 5 MPa, and the bond strength with the magnesium phosphate cement concrete layer is not less than 2.5 MPa. The elongation is greater than 30% to meet the deformation requirements of the steel bridge deck.

[0030] The magnesium phosphate cement concrete layer is poured on top of the waterproof bonding layer, with a thickness of 40-60mm (which can be adjusted according to bridge design requirements). This layer is made of magnesium phosphate cementitious cement, which includes 45%-75% cementitious materials, 18%-28% mineral admixtures, 2%-7% retarders, 1%-5% dispersants, 1%-6% viscosity reducers, 3%-9% toughening materials, and appropriate aggregates by weight percentage.

[0031] The cementitious material is prepared by acid-base neutralization reaction of recalcined magnesium oxide and ammonium dihydrogen phosphate in a molar ratio of 3:1 in the presence of water. The recalcined magnesium oxide and ammonium dihydrogen phosphate are respectively ground to a specific surface area of ​​500-700 m². 2 / kg, the magnesium oxide content in the reburned magnesium oxide is greater than 90%, and the effective component content of ammonium dihydrogen phosphate is greater than 98%. The mineral admixture is fly ash, with an active SiO2 content of 40%-50% and an active Al2O3 content of 30%-40%; the retarder is borax decahydrate with a purity greater than 95%; the dispersant is a polycarboxylate-based high-efficiency water-reducing agent; the toughening material is steel fiber or carbon fiber; the aggregate is selected graded quartz sand with a maximum particle size not exceeding 2.36mm. Induced joints are set in the magnesium phosphate cement concrete layer, with a spacing of 1 / 4-1 / 6 of the slab length and a depth of 1 / 3-1 / 2 of the pavement layer thickness, to control crack development.

[0032] The wear-resistant and anti-slip layer is applied over the magnesium phosphate cement concrete layer. Depending on the requirements, a thin layer of wear-resistant coating or asphalt concrete wear layer can be used. It is fixed to the magnesium phosphate cement concrete layer by an adhesive layer to provide good wear resistance and anti-slip performance.

[0033] This paving structure does not employ any mechanical anchoring (such as studs). Instead, it directly utilizes the chemical compatibility between the magnesium phosphate cement concrete layer and the waterproof adhesive layer to form a high-strength, durable interlayer bonding interface, achieving reliable interlayer connection.

[0034] Example 2 This embodiment describes a method for preparing a steel bridge deck pavement structure based on the magnesium phosphate cement inorganic gel material from Embodiment 1, including the following steps: S1. Surface preparation: The top surface of the steel bridge deck is shot blasted to remove rust, achieving a cleanliness level of Sa2.5, thoroughly removing oxide scale and contaminants; the surface is cleaned with high-pressure air to ensure that there are no dust, oil stains or other impurities that may affect adhesion; the steel bridge deck is preheated before applying the waterproof adhesive layer, with the temperature controlled at 40-60℃.

[0035] S2. Waterproof Adhesive Layer Construction: Accurately prepare and thoroughly stir the epoxy resin material according to the specified ratio; apply the epoxy resin evenly to the surface of the steel bridge deck using a scraper or sprayer, controlling the coating amount to 0.8-1.2 kg / m². 2 The thickness is 0.5-1.0mm, forming a continuous and uniform film layer to ensure no missed coating or accumulation.

[0036] S3. Construction of Magnesium Phosphate Cement Concrete Layer: The magnesium phosphate cement concrete should be poured before the epoxy resin initially sets (usually within 30-60 minutes); a segmented pouring method should be adopted, with construction sections set according to the bridge structure; the magnesium phosphate cement concrete mixture should be evenly laid on top of the waterproof bonding layer, with a paving thickness of 40-60mm; a vibrating beam or plate vibrator should be used for light vibration to ensure the concrete is dense while avoiding damage to the waterproof bonding layer; the surface should be leveled using a screed to control the elevation and flatness of the paving layer; induced joints should be set in the paving layer as needed, with the spacing of the induced joints being 1 / 4-1 / 6 of the slab length and the depth being 1 / 3-1 / 2 of the paving layer thickness.

[0037] S4. Curing process: Utilizing the self-curing properties of magnesium phosphate cement, no wet curing or heat curing measures are required; after pouring, cover the surface of the magnesium phosphate cement concrete layer with plastic film to prevent moisture from evaporating too quickly; under ambient temperature conditions above 20℃, light traffic can be opened 6-8 hours after pouring, and full traffic can be opened after 24 hours.

[0038] S5. Surface treatment: Before the initial setting of magnesium phosphate cement concrete, the surface is roughened to increase the adhesion to the wear-resistant and anti-slip layer; then, a second-stage epoxy resin adhesive is used to lay the bonding layer, and a thin layer of wear-resistant coating or asphalt concrete wear layer is used as the wear-resistant and anti-slip layer. The wear-resistant and anti-slip layer is fixed to the magnesium phosphate cement concrete layer through the bonding layer.

[0039] The preparation process of magnesium phosphate cement concrete includes: a) Place 45%-75% of the cementitious materials, 18%-28% of the mineral admixtures, 2%-7% of the retarder, 1%-5% of the dispersant, 1%-6% of the viscosity reducer, and 3%-9% of the toughening materials in a mixer according to the specified proportions and dry mix for 5-10 minutes to ensure uniform mixing. b) Gradually add 90% of the designed water volume to the dry mix, stir for 3-5 minutes, then add the remaining water and continue stirring for 2-3 minutes to form a uniform slurry; c) Add the selected graded quartz sand aggregate to the slurry and stir for 2-3 minutes to form a uniform concrete mixture; The dosage of retarder is adjusted according to the ambient temperature to control the setting time and ensure the operability of construction.

[0040] The properties of the prepared magnesium phosphate cement concrete are shown in the table below: Test results of magnesium phosphate concrete

[0041] The above preparation method makes full use of the rapid hardening characteristics of magnesium phosphate cement. The process is simple, the cycle is short, and the quality is easy to control. It completely avoids complex processes such as traditional stud welding and ensures that the pavement structure and the steel bridge deck form a reliable chemical-physical composite interface connection.

[0042] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A steel bridge deck pavement structure using magnesium phosphate cement inorganic gel material, characterized in that, The components, arranged from bottom to top, include a steel bridge deck, a waterproof adhesive layer, a magnesium phosphate cement concrete layer, and a wear-resistant and anti-slip layer. The steel bridge deck serves as the base layer of the pavement structure; the waterproof adhesive layer is composed of a polymer material and is coated on the surface of the steel bridge deck; the magnesium phosphate cement concrete layer is poured on top of the waterproof adhesive layer; and the wear-resistant and anti-slip layer covers the magnesium phosphate cement concrete layer. This paving structure does not use mechanical anchoring. Instead, it directly utilizes the chemical compatibility between the magnesium phosphate cement concrete layer and the waterproof bonding layer to form a high-strength and durable interlayer bonding interface.

2. The paving structure according to claim 1, characterized in that, The wear-resistant and anti-slip layer is made of thin-layer wear-resistant coating or asphalt concrete wear layer, and is fixed to the magnesium phosphate cement concrete layer by an adhesive layer.

3. The paving structure according to claim 1, characterized in that, The waterproof adhesive layer is composed of epoxy resin material, with a coating amount of 0.8-1.2 kg / m². 2 The thickness is 0.5-1.0 mm; the epoxy resin material has a bonding strength of not less than 5 MPa with the steel plate panel at 25℃, a bonding strength of not less than 2.5 MPa with the magnesium phosphate cement concrete layer, and an elongation of more than 30% to accommodate the deformation of the steel bridge deck.

4. The paving structure according to claim 1, characterized in that, The surface of the steel bridge deck is shot blasted to Sa2.5 cleanliness level. After rust removal, the surface roughness is controlled within the range of 50-100μm to increase the mechanical bonding force with the waterproof adhesive layer.

5. The paving structure according to claim 1, characterized in that, The thickness of the magnesium phosphate cement concrete layer is 40-60mm, and the thickness is adjusted according to the bridge design requirements; induced joints are set in the magnesium phosphate cement concrete layer, with the spacing of the induced joints being 1 / 4-1 / 6 of the slab length and the depth being 1 / 3-1 / 2 of the pavement layer thickness; the crack resistance is improved by adding steel fiber reinforcement.

6. The paving structure according to claim 1, characterized in that, The magnesium phosphate cement concrete layer is cast from magnesium phosphate cementitious cement; the magnesium phosphate cementitious cement is made by mixing 45%-75% cementitious materials, 18%-28% mineral admixtures, 2%-7% retarder, 1%-5% dispersant, 1%-6% viscosity reducer, 3%-9% toughening materials and appropriate amount of aggregate by mass percentage. The gelling material is prepared by reacting calcined magnesium oxide and ammonium dihydrogen phosphate in a molar ratio of 3:1 with an acid-base neutralization reaction in the presence of water.

7. The paving structure according to claim 6, characterized in that, The recalcined magnesium oxide and ammonium dihydrogen phosphate were respectively ground to a specific surface area of ​​500-700 m². 2 / kg; the mass percentage content of magnesium oxide in the recalcined magnesium oxide is greater than 90%, and the mass percentage content of the active ingredient in the ammonium dihydrogen phosphate is greater than 98%.

8. The paving structure according to claim 6, characterized in that, The mineral admixture is fly ash, in which the mass percentage content of active SiO2 is 40%~50% and the mass percentage content of active Al2O3 is 30%~40%, which improves the fluidity of the slurry and reduces the heat of hydration. The retarder is borax, specifically borax decahydrate with a purity greater than 95%; the dispersant is a polycarboxylate-based high-efficiency water-reducing agent; the toughening material is steel fiber or carbon fiber; and the aggregate is selected graded quartz sand with a maximum particle size not exceeding 2.36 mm.

9. A method for preparing a steel bridge deck pavement structure using magnesium phosphate cement inorganic gel material as described in any one of claims 1-8, characterized in that, Includes the following steps: S1. Surface treatment: The top surface of the steel bridge deck is shot blasted to remove rust, achieving a cleanliness level of Sa2.5, and thoroughly removing oxide scale and contaminants; Clean the surface with high-pressure air to ensure that there are no impurities that could affect the adhesion; preheat the steel bridge deck before applying the waterproof adhesive layer, and control the temperature at 40-60℃. S2. Waterproof Adhesive Layer Construction: Accurately prepare and thoroughly stir the epoxy resin material according to the specified ratio; apply the epoxy resin evenly to the surface of the steel bridge deck using a scraper or sprayer, controlling the coating amount to 0.8-1.2 kg / m². 2 The thickness is 0.5-1.0 mm, forming a continuous and uniform film layer to ensure no missed coating or accumulation; S3. Construction of Magnesium Phosphate Cement Concrete Layer: The subsequent pouring of magnesium phosphate cement concrete should be completed before the initial setting of the epoxy resin after the initial coating. A segmented pouring method should be adopted, with construction sections set according to the bridge structure. The magnesium phosphate cement concrete mixture should be evenly laid on top of the waterproof bonding layer, with a thickness of 40-60mm. Light vibration should be performed using a vibrating beam or plate vibrator to ensure the concrete is dense while avoiding damage to the waterproof bonding layer. The surface should be leveled using a screed to control the elevation and flatness of the pavement layer. Induction joints should be set within the pavement layer as needed, with a spacing of 1 / 4-1 / 6 of the slab length and a depth of 1 / 3-1 / 2 of the pavement layer thickness. S4. Curing process: Utilizing the self-curing properties of magnesium phosphate cement, no wet curing or heat curing measures are required; after pouring, cover the surface of the magnesium phosphate cement concrete layer with plastic film to prevent moisture from evaporating too quickly. S5. Surface treatment: Before the initial setting of magnesium phosphate cement concrete, the surface is roughened to increase the adhesion to the wear-resistant and anti-slip layer; the wear-resistant and anti-slip layer adopts a thin layer of wear-resistant coating or asphalt concrete wear layer. Before laying the wear-resistant and anti-slip layer, an adhesive layer is first laid on the magnesium phosphate cement concrete layer to fix the wear-resistant and anti-slip layer to the magnesium phosphate cement concrete layer.

10. The preparation method according to claim 9, characterized in that, The preparation process of the magnesium phosphate cement concrete includes: a) Place 45%-75% of the cementitious materials, 18%-28% of the mineral admixtures, 2%-7% of the retarder, 1%-5% of the dispersant, 1%-6% of the viscosity reducer, and 3%-9% of the toughening materials in a mixer according to the specified proportions and dry mix for 5-10 minutes to ensure uniform mixing. b) Gradually add 90% of the designed water volume to the dry mix, stir for 3-5 minutes, then add the remaining water and continue stirring for 2-3 minutes to form a uniform slurry; c) Add the selected graded quartz sand aggregate to the slurry and stir for 2-3 minutes to form a uniform concrete mixture; The dosage of retarder is adjusted according to the ambient temperature to control the setting time and ensure the operability of construction.

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