Desulfurized gypsum composite asphalt pavement reinforcing layer structure and preparation method thereof

Abstract

The application discloses a desulfurization gypsum composite asphalt pavement reinforcing layer structure and a preparation method thereof, and belongs to the field of road engineering. In view of the problems of rutting at high temperature and cracking at low temperature of traditional asphalt pavement, the technical scheme of the application comprises: from bottom to top, a modified desulfurization gypsum bonding layer, a water guide fiber layer, a desulfurization gypsum composite asphalt reinforcing layer and a waterproof and wear-resistant layer are sequentially arranged, and the layers are cooperatively matched and progressively improve the overall performance of the pavement. The desulfurization gypsum is calcined and activated, and is subjected to surface hydrophobic modification treatment, and is matched with an active activator, a composite modifier and a water guide fiber layer, so that the defects of poor water resistance and easy pulverization of the desulfurization gypsum are solved, the high-temperature stability, the low-temperature crack resistance, the water stability and the overall strength of the structure of the asphalt pavement are remarkably improved, and the application has remarkable economic benefits, environmental protection benefits and engineering application value.

Description

Technical Field

[0001] This invention relates to the field of road engineering, specifically to a desulfurized gypsum composite asphalt pavement reinforcement layer structure and its preparation method. Background Technology

[0002] Asphalt pavement has become the mainstream pavement form for highways and municipal roads in my country due to its advantages such as high driving comfort, low noise, short construction period, and convenient maintenance.

[0003] Currently, the industry primarily improves asphalt pavement performance through modified asphalt, optimized aggregate gradation, and the addition of modified fillers. However, traditional fillers often utilize high-quality building materials such as limestone powder and fly ash, resulting in high raw material costs and significant resource consumption. Meanwhile, wet desulfurization processes in thermal power plants generate large quantities of industrial byproduct desulfurization gypsum. my country's annual desulfurization gypsum emissions exceed 100 million tons. The indiscriminate dumping of large amounts of desulfurization gypsum not only occupies land resources but also causes soil and water salinization pollution. Furthermore, the resource utilization rate of solid waste is less than 60%, highlighting the urgent need for efficient disposal and utilization of this large amount of accumulated solid waste.

[0004] Existing technologies include research on the application of desulfurized gypsum in road engineering, but most studies directly incorporate raw desulfurized gypsum into the subgrade or asphalt mixture. Some studies involve applying desulfurized gypsum to the interlayer bonding layer between the base course and the surface course. However, problems such as rapid strength collapse, softening and powdering of desulfurized gypsum after contact with water, and the migration of unstable free gypsum and soluble salts from the gypsum to the surface with the continuous penetration of water, causing corrosion to the asphalt, have not been effectively solved. As a result, the application of desulfurized gypsum in asphalt highways has remained in the experimental stage and cannot be effectively applied in practice. Summary of the Invention

[0005] To overcome the shortcomings of the aforementioned related technologies, this invention proposes a desulfurized gypsum composite asphalt pavement reinforcement layer structure, which can improve pavement strength and quality.

[0006] To achieve the above-mentioned technical objectives, the present invention provides a desulfurized gypsum composite asphalt pavement reinforcement layer structure. The desulfurized gypsum composite asphalt pavement reinforcement layer structure includes: a modified desulfurized gypsum bonding layer, a desulfurized gypsum composite asphalt reinforcement layer, a waterproof and wear-resistant layer, and a water-conducting fiber layer.

[0007] The modified desulfurized gypsum bonding layer is disposed on the base surface, the desulfurized gypsum composite asphalt reinforcement layer is fixed on the modified desulfurized gypsum bonding layer, the waterproof and wear-resistant layer is disposed on the desulfurized gypsum composite asphalt reinforcement layer, and a water-conducting fiber layer is disposed between the modified desulfurized gypsum bonding layer and the desulfurized gypsum composite asphalt reinforcement layer.

[0008] The modified desulfurized gypsum adhesive layer is formed by mixing modified desulfurized gypsum powder, water-based polyurethane adhesive, active activator, slag powder and water and then curing it.

[0009] The water-conducting fiber layer includes: a mesh fabric and absorbent fibers. The mesh fabric is a high-toughness polyester filament needle-punched geotextile woven from polyethylene terephthalate. Multiple absorbent fibers are also fixed in the lower layer of the mesh fabric. The absorbent fibers are disposed in the modified desulfurized gypsum bonding layer and are tapered gradient single fibers.

[0010] The desulfurized gypsum composite asphalt reinforcement layer is formed by uniformly mixing and compacting base asphalt, modified desulfurized gypsum filler, coarse and fine aggregates, composite modifier, and anti-stripping agent.

[0011] Preferably, the thickness of the modified desulfurized gypsum bonding layer is 8mm to 12mm. The thickness of the desulfurized gypsum composite asphalt reinforcing layer is 40mm to 60mm. The thickness of the waterproof and wear-resistant surface layer is 3mm to 5mm.

[0012] Preferably, the absorbent fiber is a conical basalt fiber. The conical basalt fiber has a length of 6mm to 12mm on the outer part of the mesh, a diameter of 16μm to 20μm at the large diameter end, and a diameter of 3μm to 6μm at the small diameter end.

[0013] Preferably, the mesh fabric is composited with multiple rows of protrusions on the side near the modified desulfurized gypsum adhesive layer. Each protrusion is a hemispherical or frustum-shaped protrusion with a height of 1.5mm to 3mm and a spacing of 5mm to 8mm.

[0014] On the other hand, the present invention also provides a method for preparing a desulfurized gypsum composite asphalt pavement reinforcement layer. The method for preparing the desulfurized gypsum composite asphalt pavement reinforcement layer includes the following steps:

[0015] S1. Pretreatment and modification of desulfurized gypsum: Select desulfurized gypsum by-product of thermal power industry, remove impurities and clumps, crush and place it in calcination equipment at a constant temperature of 180℃~220℃ for 2h~3h to remove free water and water of crystallization. After cooling to room temperature, grind it into 200 mesh~300 mesh powder. Place the desulfurized gypsum powder in a mixing tank, spray with silane coupling agent and paraffin composite emulsion, stir at room temperature for 15min~20min to uniformly coat the powder surface, and dry at 105℃~110℃ to constant weight to obtain modified desulfurized gypsum filler for later use.

[0016] S2. Preparation of modified desulfurized gypsum bonding base layer slurry: Weigh the modified desulfurized gypsum powder, quicklime activator and fly ash according to the ratio, dry mix evenly, add water-based polyurethane binder and a certain amount of water, and continue stirring for 5 min to 10 min to obtain a uniform bonding slurry without lumps.

[0017] S3. Base layer paving and curing: Clean the top surface of the road base layer, remove dust and moisture, and use a paver to evenly spread the bonding slurry. The paving thickness is controlled between 8mm and 12mm. Lay the water-conducting fiber layer on top of the bonding slurry layer. After the water-conducting fiber layer is leveled, let it stand at room temperature for 30 to 40 minutes to cure, forming a high-strength bonding base layer. Drainage blind holes are set on the road slopes on both sides of the water-conducting fiber layer. The drainage blind holes are connected to the protrusions of the water-conducting fiber layer.

[0018] S4. Preparation of desulfurized gypsum composite asphalt mixture: Preheat coarse and fine aggregates to 160℃~170℃, add them to the mixing equipment and dry mix for 10s~15s; heat the base asphalt to 155℃~165℃, spray it onto the aggregates and mix for 30s; then add modified desulfurized gypsum filler, composite modifier, and anti-stripping agent, and continue mixing for 60s~90s until the mixture has a uniform color and no segregation or lumps, thus obtaining the composite asphalt mixture.

[0019] S5. Enhanced Intermediate Layer Paving and Compaction: Modified emulsified asphalt tack coat is applied over the water-conducting fiber layer, followed by the application of 3mm-5mm diameter crushed stone. The crushed stone is compacted and embedded into the modified emulsified asphalt tack coat. The uniformly mixed composite asphalt mixture is then spread onto the cured bonding base layer surface, with a paving thickness of 40mm-60mm. Paving is carried out using a paver at a uniform speed of 2m / min-4m / min. Compaction is immediately performed after paving, consisting of two static compactions, three weak vibration compactions, and a final static compaction finish. The compaction temperature is controlled at 140℃-155℃, and the compaction degree is ≥98%.

[0020] S6. Surface layer construction and forming: When the temperature of the reinforced intermediate layer drops to 80℃~90℃, spray the SBS modified asphalt waterproof and wear-resistant coating evenly, and simultaneously spread ultra-fine wear-resistant quartz sand. Allow it to cool and solidify naturally to form a waterproof and wear-resistant surface layer, thus completing the overall reinforcement layer construction.

[0021] Preferably, in step S1, the solid content of the silane coupling agent and paraffin composite emulsion is 8% to 12%, and the spraying amount is 2% to 4% of the mass of the desulfurized gypsum powder.

[0022] Preferably, in step S4, the mixing temperature is maintained at 150℃~170℃ throughout the mixing process, the discharge temperature of the mixture is controlled at 155℃~160℃, and the waste temperature is not lower than 140℃.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] This invention utilizes desulfurized gypsum, a form of industrial solid waste recycling. The desulfurized gypsum, after hydration, produces ettringite and dihydrate gypsum crystals. These crystals are interlocked and have strong interfacial bonding with cement-stabilized crushed stone base courses and asphalt mixtures. This application employs water-based polyurethane to form a hydrophobic film, blocking the water absorption channels of the desulfurized gypsum layer. Furthermore, slag powder adsorbs moisture within the desulfurized gypsum. Simultaneously, the slag and active activator combine to form water-insoluble CSH gel, effectively blocking the pores in the desulfurized gypsum. Finally, the strong water absorption and water barrier properties of the water-conducting fiber layer solve the problem of desulfurized gypsum pulverizing after soaking in water, making desulfurized gypsum a practically valuable interlayer bonding layer for asphalt pavements. Attached Figure Description

[0025] Figure 1 This is a structural diagram of the present invention;

[0026] Figure 2 This is a structural diagram of the water-conducting fiber layer of the present invention;

[0027] Figure 3 This is a bottom view of the water-conducting fiber layer of the present invention. Detailed Implementation

[0028] To make the above-mentioned objects, features, and advantages of the present invention more apparent and understandable, 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.

[0029] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this 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, they should not be construed as limitations on this invention.

[0030] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0031] This invention provides a desulfurized gypsum composite asphalt pavement reinforcement layer structure. In one aspect, this invention provides a desulfurized gypsum composite asphalt pavement reinforcement layer structure. The desulfurized gypsum composite asphalt pavement reinforcement layer structure includes: a modified desulfurized gypsum bonding layer, a desulfurized gypsum composite asphalt reinforcement layer, a waterproof and wear-resistant layer, and a water-conducting fiber layer.

[0032] The modified desulfurized gypsum bonding layer is disposed on the base surface, the desulfurized gypsum composite asphalt reinforcement layer is fixed on the modified desulfurized gypsum bonding layer, the waterproof and wear-resistant layer is disposed on the desulfurized gypsum composite asphalt reinforcement layer, and a water-conducting fiber layer is disposed between the modified desulfurized gypsum bonding layer and the desulfurized gypsum composite asphalt reinforcement layer.

[0033] The modified desulfurized gypsum adhesive layer is formed by mixing modified desulfurized gypsum powder, water-based polyurethane adhesive, active activator and water and then curing it.

[0034] The desulfurized gypsum composite asphalt reinforcement layer is formed by uniformly mixing and compacting base asphalt, modified desulfurized gypsum filler, coarse and fine aggregates, composite modifier, and anti-stripping agent.

[0035] The water-conducting fiber layer includes: a mesh fabric 1 and water-absorbing fibers 2. The mesh fabric 1 is a high-toughness polyester filament needle-punched geotextile woven from polyethylene terephthalate. A plurality of water-absorbing fibers 2 are fixed in the lower layer of the mesh fabric 1. The water-absorbing fibers 2 are disposed in the modified desulfurized gypsum bonding layer. The water-absorbing fibers 2 are tapered gradient single fibers.

[0036] The desulfurized gypsum composite asphalt reinforcement layer is formed by uniformly mixing and compacting base asphalt, modified desulfurized gypsum filler, coarse and fine aggregates, composite modifier, and anti-stripping agent.

[0037] The absorbent fiber 2 is made of conical basalt fiber. The length of the conical basalt fiber on the outer part of the mesh 1 is 6mm to 12mm, the diameter of the large diameter end is 16μm to 20μm, and the diameter of the small diameter end is 3μm to 6μm.

[0038] Conical basalt fibers are readily available, with mature products on the market, and they do not readily react chemically with desulfurized gypsum. The conical basalt fibers extend into the modified desulfurized gypsum bonding layer, which on the one hand enhances the stability between the water-conducting fiber layer and the desulfurized gypsum bonding layer, preventing slippage; on the other hand, the conical basalt fibers can absorb moisture from the desulfurized gypsum through unidirectional capillary action.

[0039] To further improve water absorption and energy absorption and prevent water from entering the desulfurized gypsum within the water-conducting fiber layer, the small-diameter end of the conical basalt fiber is hydrophobically modified, while the large-diameter end is hydroxylated and hydrophilic etched.

[0040] Conical basalt fibers can be woven together with geotextile warp and weft fiber nets during the prevention and control of the grid cloth 1, reducing the possibility of conical basalt fibers falling off.

[0041] The mesh fabric 1 is composited with multiple rows of protrusions 3 on the side near the modified desulfurized gypsum adhesive layer. Each protrusion 3 is a hemispherical or frustum protrusion with a protrusion height of 1.5mm to 3mm and a protrusion spacing of 5mm to 8mm.

[0042] The multiple rows of raised dots 3 can be made of strip-shaped PET sheet with a flat base and raised dots 3 on the other side. The base is bonded and fixed to the mesh fabric 1 by a hot-melt process. The PET sheet is 3mm thick.

[0043] The raised dots in the same row can form a natural cavity between the mesh cloth 1 and the desulfurized gypsum bonding layer, which can collect the water absorbed by the capillary action of the water-absorbing fibers and drain it to both sides of the road.

[0044] To further improve the drainage performance of the cavity, the water-conducting fiber layer can be arranged at an angle of 1° to 3° from the center line of the road to both sides of the road, from high to low.

[0045] Preferably, the modified desulfurized gypsum filler is pretreated desulfurized gypsum powder. The pretreatment process is as follows: the original desulfurized gypsum is screened to remove impurities, calcined and activated at 180℃~220℃ for 2h~3h, cooled and ground to 200 mesh~300 mesh, and then surface hydrophobic modification is performed using a silane coupling agent and paraffin composite emulsion, and then dried to obtain the modified desulfurized gypsum powder. The modified desulfurized gypsum powder has a moisture content ≤1.5% and an activity index ≥95%.

[0046] Preferably, the thickness of the modified desulfurized gypsum adhesive layer is 8mm to 12mm.

[0047] The thickness of the desulfurized gypsum composite asphalt reinforcement layer is 40mm to 60mm.

[0048] The thickness of the waterproof and wear-resistant surface layer is 3mm to 5mm.

[0049] Preferably, the modified desulfurized gypsum filler is pretreated desulfurized gypsum powder. The pretreatment process is as follows: the original desulfurized gypsum is screened to remove impurities, calcined and activated at 180℃~220℃ for 2h~3h, cooled and ground to 200 mesh~300 mesh, and then surface hydrophobic modification is performed using a silane coupling agent and paraffin composite emulsion, and then dried to obtain the modified desulfurized gypsum powder. The modified desulfurized gypsum powder has a moisture content ≤1.5% and an activity index ≥95%.

[0050] Preferably, the modified desulfurized gypsum adhesive base material is formulated in the following proportions by weight: 60-70 parts modified desulfurized gypsum powder, 15-20 parts water-based polyurethane adhesive, 3-5 parts quicklime activator, 5-8 parts fly ash, and the remainder is water.

[0051] Preferably, by weight, the raw material ratio of the desulfurized gypsum composite asphalt reinforced intermediate layer is: 4.5 to 6 parts of base asphalt, 8 to 12 parts of modified desulfurized gypsum filler, 55 to 65 parts of coarse aggregate, 18 to 25 parts of fine aggregate, 1 to 2 parts of composite modifier, and 0.2 to 0.5 parts of anti-stripping agent; the composite modifier is a mixture of polystyrene-butadiene block copolymer and nano-silica at a mass ratio of 3:1.

[0052] Preferably, the waterproof and wear-resistant surface layer is a thin layer of SBS modified bitumen, internally doped with ultrafine wear-resistant quartz sand and hydrophobic additives, with a porosity ≤3% and a permeability coefficient ≤1×10⁻⁶. .

[0053] On the other hand, the present invention also provides a method for preparing a desulfurized gypsum composite asphalt pavement reinforcement layer. The method for preparing the desulfurized gypsum composite asphalt pavement reinforcement layer includes the following steps:

[0054] S1. Pretreatment and modification of desulfurized gypsum: Select desulfurized gypsum by-product of thermal power industry, remove impurities and clumps, crush and place it in calcination equipment at a constant temperature of 180℃~220℃ for 2h~3h to remove free water and water of crystallization. After cooling to room temperature, grind it into 200 mesh~300 mesh powder. Place the desulfurized gypsum powder in a mixing tank, spray with silane coupling agent and paraffin composite emulsion, stir at room temperature for 15min~20min to uniformly coat the powder surface, and dry at 105℃~110℃ to constant weight to obtain modified desulfurized gypsum filler for later use.

[0055] S2. Preparation of modified desulfurized gypsum bonding base layer slurry: Weigh the modified desulfurized gypsum powder, quicklime activator and fly ash according to the ratio, dry mix evenly, add water-based polyurethane binder and a certain amount of water, and continue stirring for 5 min to 10 min to obtain a uniform bonding slurry without lumps.

[0056] S3. Base layer paving and curing: Clean the top surface of the road base layer, remove dust and moisture, and use a paver to evenly spread the bonding slurry. The paving thickness is controlled between 8mm and 12mm. Lay the water-conducting fiber layer on top of the bonding slurry layer. After the water-conducting fiber layer is leveled, let it stand at room temperature for 30 to 40 minutes to cure, forming a high-strength bonding base layer. Drainage blind holes are set on the road slopes on both sides of the water-conducting fiber layer. The drainage blind holes are connected to the protrusions 3 of the water-conducting fiber layer.

[0057] S4. Preparation of desulfurized gypsum composite asphalt mixture: Preheat coarse and fine aggregates to 160℃~170℃, add them to the mixing equipment and dry mix for 10s~15s; heat the base asphalt to 155℃~165℃, spray it onto the aggregates and mix for 30s; then add modified desulfurized gypsum filler, composite modifier, and anti-stripping agent, and continue mixing for 60s~90s until the mixture has a uniform color and no segregation or lumps, thus obtaining the composite asphalt mixture.

[0058] S5. Enhanced Intermediate Layer Paving and Compaction: Modified emulsified asphalt tack coat is applied over the water-conducting fiber layer, followed by the application of 3mm-5mm diameter crushed stone. The crushed stone is compacted and embedded into the modified emulsified asphalt tack coat. The uniformly mixed composite asphalt mixture is then spread onto the cured bonding base layer surface, with a paving thickness of 40mm-60mm. Paving is carried out using a paver at a uniform speed of 2m / min-4m / min. Compaction is immediately performed after paving, consisting of two static compactions, three weak vibration compactions, and a final static compaction finish. The compaction temperature is controlled at 140℃-155℃, and the compaction degree is ≥98%.

[0059] S6. Surface layer construction and forming: When the temperature of the reinforced intermediate layer drops to 80℃~90℃, spray the SBS modified asphalt waterproof and wear-resistant coating evenly, and simultaneously spread ultra-fine wear-resistant quartz sand. Allow it to cool and solidify naturally to form a waterproof and wear-resistant surface layer, thus completing the overall reinforcement layer construction.

[0060] Preferably, in step S1, the solid content of the silane coupling agent and paraffin composite emulsion is 8% to 12%, and the spraying amount is 2% to 4% of the mass of the desulfurized gypsum powder.

[0061] Preferably, in step S4, the mixing temperature is maintained at 150℃~170℃ throughout the mixing process, the discharge temperature of the mixture is controlled at 155℃~160℃, and the waste temperature is not lower than 140℃.

[0062] In the description of this specification, specific features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments or examples.

[0063] The above are merely specific embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A desulfurized gypsum composite asphalt pavement reinforcement layer structure, characterized in that, include: Modified desulfurized gypsum bonding layer, desulfurized gypsum composite asphalt reinforcement layer, waterproof and wear-resistant layer, and water-conducting fiber layer; The modified desulfurized gypsum bonding layer is disposed on the base surface, the desulfurized gypsum composite asphalt reinforcement layer is fixed on the modified desulfurized gypsum bonding layer, the waterproof and wear-resistant layer is disposed on the desulfurized gypsum composite asphalt reinforcement layer, and a water-conducting fiber layer is disposed between the modified desulfurized gypsum bonding layer and the desulfurized gypsum composite asphalt reinforcement layer. The modified desulfurized gypsum adhesive layer is formed by mixing modified desulfurized gypsum powder, water-based polyurethane adhesive, active activator, slag powder and water and then curing it. The water-conducting fiber layer includes: a mesh fabric and water-absorbing fibers. The mesh fabric is a high-toughness polyester filament needle-punched geotextile woven from polyethylene terephthalate. Multiple water-absorbing fibers are also fixed in the lower layer of the mesh fabric. The water-absorbing fibers are disposed in the modified desulfurized gypsum bonding layer and are tapered gradient single fibers. The desulfurized gypsum composite asphalt reinforcement layer is formed by uniformly mixing and compacting base asphalt, modified desulfurized gypsum filler, coarse and fine aggregates, composite modifier, and anti-stripping agent.

2. The desulfurized gypsum composite asphalt pavement reinforcement layer structure according to claim 1, characterized in that, The thickness of the modified desulfurized gypsum bonding layer is 8mm to 12mm; The thickness of the desulfurized gypsum composite asphalt reinforcement layer is 40mm to 60mm. The thickness of the waterproof and wear-resistant surface layer is 3mm to 5mm.

3. The desulfurized gypsum composite asphalt pavement reinforcement layer structure according to claim 1, characterized in that, The absorbent fiber is made of tapered basalt fiber. The tapered basalt fiber has a length of 6mm to 12mm on the outer side of the mesh, a diameter of 16μm to 20μm at the large diameter end, and a diameter of 3μm to 6μm at the small diameter end.

4. The desulfurized gypsum composite asphalt pavement reinforcement layer structure according to claim 1, characterized in that, The mesh fabric near the modified desulfurized gypsum adhesive layer has multiple rows of protrusions. Each protrusion is a hemispherical or frustum-shaped protrusion with a height of 1.5mm to 3mm and a spacing of 5mm to 8mm.

5. A method for preparing a desulfurized gypsum composite asphalt pavement reinforcement layer, characterized in that, Includes the following steps: S1. Pretreatment and modification of desulfurized gypsum: Select desulfurized gypsum by-product of thermal power industry, remove impurities and clumps, crush and place it in calcination equipment at 180℃~220℃ for 2h~3h to remove free water and crystal water, cool to room temperature and grind to 200 mesh~300 mesh powder; place the desulfurized gypsum powder in a mixing tank, spray with silane coupling agent and paraffin composite emulsion, stir at room temperature for 15min~20min to uniformly coat the powder surface, dry at 105℃~110℃ to constant weight, and obtain modified desulfurized gypsum filler for use; S2. Preparation of modified desulfurized gypsum bonding base layer slurry: Weigh the modified desulfurized gypsum powder, quicklime activator and fly ash according to the ratio, dry mix evenly, add water-based polyurethane binder and a certain amount of water, and continue stirring for 5 min to 10 min to obtain a uniform bonding slurry without lumps. S3. Base layer paving and curing: Clean the top surface of the road base layer, remove dust and moisture, and use a paver to evenly spread the bonding slurry. The paving thickness is controlled at 8mm to 12mm. Lay the water-conducting fiber layer on top of the bonding slurry layer. After the water-conducting fiber layer is leveled, let it stand at room temperature for 30 to 40 minutes to cure, forming a high-strength bonding base layer. Drainage blind holes are set on the road slopes on both sides of the water-conducting fiber layer. The drainage blind holes are connected to the protrusions of the water-conducting fiber layer. S4. Preparation of desulfurized gypsum composite asphalt mixture: Preheat coarse and fine aggregates to 160℃~170℃, add them to the mixing equipment and dry mix for 10s~15s; heat the base asphalt to 155℃~165℃, spray it onto the aggregates and mix for 30s; then add modified desulfurized gypsum filler, composite modifier, and anti-stripping agent, and continue mixing for 60s~90s until the mixture has a uniform color and no segregation or lumps, thus obtaining the composite asphalt mixture; S5. Enhanced Intermediate Layer Paving and Compaction: Modified emulsified asphalt tack coat is applied over the water-conducting fiber layer, followed by the application of 3mm-5mm diameter crushed stone. The crushed stone is compacted and embedded into the modified emulsified asphalt tack coat. The uniformly mixed composite asphalt mixture is then spread onto the cured bonding base layer surface, with a paving thickness of 40mm-60mm. Paving is carried out using a paver at a uniform speed of 2m / min-4m / min. Compaction is immediately performed after paving, consisting of two static compactions, three weak vibration compactions, and a final static compaction finish. The compaction temperature is controlled at 140℃-155℃, and the compaction degree is ≥98%. S6. Surface layer construction and forming: When the temperature of the reinforced intermediate layer drops to 80℃~90℃, spray the SBS modified asphalt waterproof and wear-resistant coating evenly, and simultaneously spread ultra-fine wear-resistant quartz sand. Allow it to cool and solidify naturally to form a waterproof and wear-resistant surface layer, thus completing the overall reinforcement layer construction.

6. The method for preparing the desulfurized gypsum composite asphalt pavement reinforcement layer according to claim 8, characterized in that: In step S1, the solid content of the silane coupling agent and paraffin composite emulsion is 8% to 12%, and the spraying amount is 2% to 4% of the mass of the desulfurized gypsum powder.

7. The method for preparing the desulfurized gypsum composite asphalt pavement reinforcement layer according to claim 8, characterized in that: In step S4, the mixing temperature is maintained at 150℃~170℃ throughout the mixing process, the discharge temperature of the mixture is controlled at 155℃~160℃, and the waste temperature is not lower than 140℃.

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