Biomass low-carbon semi-flexible pavement and preparation method thereof

Abstract

The application discloses a kind of biomass low-carbon semi-flexible pavement and preparation method thereof, belong to cement asphalt material technical field.Biomass low-carbon semi-flexible pavement, including 72% to 84% biomass asphalt mixture and 16% to 28% filling material;Oil stone ratio of biomass asphalt mixture is 4% to 5%;Asphalt material includes: base asphalt 74% to 83%, modified soybean oil 8% to 12%, organic bentonite 7% to 9%, plasticizer 1.5% to 3.5%, antioxidant 0.5% to 1.5%;Filling material includes: silicate cement 58% to 70%, rice husk ash 15% to 20%, fly ash 8% to 10%, silica fume 5% to 6%, sodium lignosulfonate 1.5% to 3.5%, coupling agent 0.5% to 1.5%.The present application can solve the problem of existing biomass semi-flexible pavement load capacity, low temperature crack resistance and poor durability.

Description

Technical Field

[0001] This invention relates to the field of cement and asphalt materials technology, and in particular to a biomass low-carbon semi-flexible pavement and its preparation method. Background Technology

[0002] In recent years, global traffic volume has continued to surge, vehicle axle loads have increased, and the summer heatwave has lengthened, leading to increasingly prominent problems such as rutting and shoving at key road sections like urban intersections, bus stops, and traffic light intersections. Traditional asphalt concrete pavements, due to insufficient high-temperature stability, are unable to withstand the permanent deformation caused by heavy traffic, resulting in a significant increase in pavement maintenance frequency and costs. Semi-flexible pavements, with their combination of the flexibility of asphalt materials and the high strength of cement-based materials, have become an important technological direction for solving this problem.

[0003] However, the preparation of existing semi-flexible pavements still faces significant technical bottlenecks and environmental shortcomings: on the one hand, their core materials heavily rely on petroleum-based modified asphalt and ordinary silicate cement, both of which have high carbon emission intensity during production; on the other hand, although bio-based materials (such as vegetable oils) and industrial waste (such as fly ash) have been attempted to be applied to road engineering, they generally have performance defects: bio-based asphalt has insufficient high-temperature rutting resistance, making it difficult to meet the needs of heavy-load traffic; the interfacial compatibility between bio-based organic materials and inorganic grouting materials is poor, which can easily lead to interlayer delamination and affect the overall integrity of the pavement structure.

[0004] Furthermore, existing biomass semi-flexible pavements also face prominent problems such as weak load-bearing capacity, poor low-temperature crack resistance, and insufficient long-term durability, which limit their large-scale application in practical engineering. Therefore, developing a biomass low-carbon semi-flexible pavement and its preparation method that can significantly reduce carbon emissions, meet environmental protection requirements, and possess excellent road performance and high durability has become a key technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to provide a biomass low-carbon semi-flexible pavement and its preparation method, which solves the problems of low load capacity, poor low-temperature crack resistance and poor durability of existing biomass semi-flexible pavements.

[0006] To achieve the above objectives, this invention provides a biomass low-carbon semi-flexible pavement, comprising 72%-84% by volume biomass asphalt mixture and 16%-28% by volume filler material; the asphalt-aggregate ratio of the biomass asphalt mixture is 4%-5%; the asphalt component in the biomass asphalt mixture comprises the following components by mass percentage: 74%-83% base asphalt, 8%-12% modified soybean oil, 7%-10% organic bentonite, 1.5%-3.5% plasticizer, and 0.5%-1.5% antioxidant; the filler material comprises the following components by mass percentage: 58%-70% silicate cement, 15%-20% rice husk ash, 8%-10% fly ash, 5%-6% silica fume, 1.5%-3.5% sodium lignosulfonate, and 0.5%-1.5% coupling agent.

[0007] Preferably, the modified soybean oil is epoxidized modified soybean oil, and the epoxide value of the epoxidized modified soybean oil is... 6%.

[0008] Preferably, the plasticizer is dibutyl phthalate, the antioxidant is 2264, and the silane coupling agent is KH-550.

[0009] Preferably, the specific surface area of ​​the rice husk ash is not less than 400 m². 2 / kg.

[0010] Preferably, the water-to-binder ratio of the filler material is 0.48-0.5.

[0011] The above-mentioned method for preparing biomass low-carbon semi-flexible pavement includes the following steps:

[0012] S1. Preparation of modified soybean oil: Soybean oil is mixed with formic acid and concentrated sulfuric acid at 50℃-60℃ until homogeneous. While stirring, hydrogen peroxide with a mass concentration of 30%-50% is added dropwise. After the reaction, the mixture is purified by separation. The oil phase is washed with 5% Na2CO3 solution until neutral. After washing with hot deionized water, anhydrous sodium sulfate is added and stirred to dehydrate. After filtration, modified soybean oil is obtained.

[0013] S2, Preparation of asphalt material;

[0014] S3. Preparation of filler material;

[0015] S4. Mix asphalt material with aggregates and compact them into a porous biomass asphalt mixture with interconnected pores; after cooling, inject filler material into the porous biomass asphalt mixture, and after solidification, a semi-flexible pavement is obtained.

[0016] Preferably, in step S1, the amount of formic acid is 8%-12% of the soybean oil mass, the mass fraction of concentrated sulfuric acid is 95%-98%, the amount of concentrated sulfuric acid is 0.2%-0.5% of the soybean oil mass, the amount of hydrogen peroxide is 40%-60% of the soybean oil mass, and the reaction time is 3-5 hours.

[0017] Preferably, in step S2, the asphalt preparation process includes the following steps:

[0018] S21. Preheat the base asphalt to a fluid state;

[0019] S22. Add modified soybean oil and half of the plasticizer at ≤150℃ and mix.

[0020] S23. Add antioxidants at 140℃;

[0021] S24. Premix the organic bentonite with the remaining plasticizer into a slurry, add it to the base asphalt, and mix at a high speed of 4000 rpm for 60 minutes at 160℃-170℃. Then, mix at a low speed of 500 rpm-1000 rpm and cure for 1-2 hours to obtain the asphalt material.

[0022] Preferably, in step S3, the preparation process of the filler material includes the following steps:

[0023] S31. Dry mix silicate cement, rice husk ash, fly ash, silica fume, sodium lignosulfonate, and coupling agent according to the mass ratio to obtain a uniform dry mix.

[0024] S32. Add water to the mixer at a water-to-binder ratio of 0.48-0.5, then add the dry mix to the mixer. First, mix at a low speed of 500 rpm-1000 rpm for 20 s-50 s, then mix at a high speed of 4000 rpm for 1 minute-3 minutes to obtain the filler material.

[0025] Preferably, the biomass asphalt mixture has a penetration of 60×0.1mm-80×0.1mm at 25°C, a softening point ≥75°C, and a kinematic viscosity of 1.8 at 135°C. -3.0 The elastic recovery rate at 25℃ is ≥85%;

[0026] The initial flowability of the filler material is 10 s-14 s, the flowability at 30 min is ≤18 s, the water bleeding rate at 3 h is ≤0.01%, and the compressive strength at 7 days is ≥15 MPa.

[0027] The interfacial strength between biomass asphalt mixture and filler material is ≥2.15 MPa, the dynamic stability is ≥26000 cycles / mm, and the bending tensile strain at -10℃ is ≥3200 με.

[0028] The advantages and positive effects of the biomass low-carbon semi-flexible pavement and its preparation method described in this invention are as follows:

[0029] 1. This invention achieves source carbon reduction at the material level through a dual bio-based / waste utilization strategy, which uses epoxidized soybean oil to replace part of petroleum asphalt and ultrafine rice husk ash to replace part of cement. Preliminary life cycle assessment (LCA) shows that the pavement system of this invention reduces carbon emissions by approximately 28.5% compared to traditional semi-flexible pavements. Simultaneously, each kilometer of pavement can absorb approximately 12.6 tons of rice husk ash, effectively promoting the high-value utilization of agricultural waste.

[0030] 2. The epoxidized soybean oil of the present invention introduces epoxy groups, which form a stable network structure with organic bentonite under high-speed shearing action, significantly improving the high-temperature stability (softening point ≥78℃) and elastic recovery ability (25℃, ≥95%) of bio-based asphalt. Its resistance to permanent deformation is better than or equivalent to that of traditional SBS modified asphalt.

[0031] 3. Ultrafine rice husk ash has extremely high pozzolanic activity and micro-aggregate filling effect. When combined with silica fume and fly ash, it significantly optimizes the particle size distribution of the cementitious system, thereby obtaining high early strength (7d compressive strength ≥35MPa) and extremely low bleeding rate (3h bleeding rate ≤0.01%), ensuring the uniformity and compactness of the grouting.

[0032] 4. The silane coupling agent (KH-550) used in this invention can form a strong chemical bond with the cement hydration products in the grouting material at one end, and can entangle or react with the organic long chains in the bio-based asphalt at the other end, thereby constructing a strong "molecular bridge" at the asphalt-cement interface, improving the interfacial bonding strength, and the interfacial bonding strength can reach more than 2.48 MPa, effectively avoiding the risk of interlayer debonding.

[0033] 5. The semi-flexible pavement described in this invention not only has a dynamic stability of over 26,000 cycles / mm and extremely strong resistance to rutting, but also a low-temperature bending tensile strain of over 3200 με at -10℃, indicating that it also has good low-temperature crack resistance.

[0034] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0035] Figure 1 This is a flowchart illustrating the preparation process of the semi-flexible pavement of the present invention.

[0036] Figure 2 The filler material specimen prepared for this invention. Detailed Implementation

[0037] In this application, unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains. In case of any inconsistency, the meaning set forth in this specification or derived from the content described herein shall prevail. Furthermore, the terminology used herein is for the purpose of describing embodiments of this application only and is not intended to limit the scope of this application.

[0038] The embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0039] A biomass low-carbon semi-flexible pavement comprises 72%-84% biomass asphalt mixture and 16%-28% filler material by volume. The asphalt-aggregate ratio of the biomass asphalt mixture is 4%-5%, which is the ratio of asphalt to aggregate in the biomass asphalt mixture. The asphalt in the biomass asphalt mixture includes the following components by mass percentage: 74%-83% base asphalt, 8%-12% modified soybean oil, 7%-10% organic bentonite, 1.5%-3.5% plasticizer, and 0.5%-1.5% antioxidant. The filler material includes the following components by mass percentage: 58%-70% silicate cement, 15%-20% rice husk ash, 8%-10% fly ash, 5%-6% silica fume, 1.5%-3.5% sodium lignosulfonate, and 0.5%-1.5% coupling agent.

[0040] The modified soybean oil is epoxidized soybean oil, and the epoxy value of the epoxidized soybean oil is... 6%. In high summer temperatures, mixtures using pure biomass asphalt become too soft, easily leading to permanent deformation, i.e., rutting, under vehicle loads. The complex chemical composition of bio-oil may result in poor adhesion to acidic or certain neutral aggregates, making it prone to peeling under moisture erosion, leading to water damage to the mixture. To address the inherent defects of biomass asphalt, increase adhesion to aggregates, and improve rutting resistance, soybean oil is epoxidized. Epoxidized soybean oil introduces epoxy groups, forming a stable network structure with organobentonite under high-speed shear, significantly improving the high-temperature stability and elastic recovery of bio-based asphalt mixtures, thus enhancing their resistance to permanent deformation.

[0041] The plasticizer is dibutyl phthalate, and the antioxidant is 2264 (C). 23 H 32 O2), the silane coupling agent is KH-550.

[0042] The specific surface area of ​​rice husk ash is not less than 400 m². 2 / kg. The water-cement ratio of the filler material is 0.48-0.5. The ultrafine rice husk ash used in the filler material has extremely high pozzolanic activity and micro-aggregate filling effect. When compounded with silica fume and fly ash, it optimizes the particle size distribution of the cementitious system, thereby obtaining high early strength and extremely low bleeding rate, which is beneficial to improving the uniformity and compactness of grouting.

[0043] A silane coupling agent is added to the filler material. One end of the silane coupling agent molecule can form a strong chemical bond with the cement hydration products in the filler material, while the other end can entangle or react with the long organic chains in the bio-based asphalt mixture. This creates a strong "molecular bridge" at the asphalt-cement interface, which helps to improve the bonding strength between the filler material and the biomass asphalt mixture and avoids the risk of interlayer debonding.

[0044] like Figure 1 As shown, the preparation method of biomass low-carbon semi-flexible pavement includes the following steps:

[0045] S1. Preparation of modified soybean oil: Soybean oil is mixed with formic acid and concentrated sulfuric acid at 50℃-60℃ until homogeneous. While stirring, hydrogen peroxide with a mass concentration of 30%-50% is added dropwise. After the reaction, the mixture is purified by separation. The oil phase is washed with a 5% Na2CO3 solution until neutral. After washing with hot deionized water, anhydrous sodium sulfate is added and stirred to dehydrate. After filtration, modified soybean oil is obtained.

[0046] The amount of formic acid used is 8%-12% of the soybean oil mass, the mass concentration of concentrated sulfuric acid is 95%-98%, the amount of concentrated sulfuric acid used is 0.2%-0.5% of the soybean oil mass, the amount of hydrogen peroxide used is 40%-60% of the soybean oil mass, and the reaction time is 3-5 hours.

[0047] Under concentrated sulfuric acid catalysis, peroxyformic acid, generated from formic acid and hydrogen peroxide, is used to epoxidize the unsaturated double bonds in soybean oil, thereby converting the nonpolar double bonds into highly reactive epoxy groups. This modification fundamentally changes the chemical properties of soybean oil, transforming it from a simple plasticizer into an active modifier. Under high-speed shear and high-temperature conditions, the epoxy groups are activated and can undergo ring-opening reactions with the hydroxyl groups on the surface of organobentonite. The epoxy groups of ESO (epoxidized soybean oil) can also react with these acidic groups in asphalt, improving the compatibility between bio-oil and petroleum asphalt and preventing phase separation.

[0048] S2. Preparation of asphalt mix. The preparation process of asphalt mix includes the following steps:

[0049] S21. Preheat the base asphalt to a fluid state.

[0050] S22. Add modified soybean oil and half of the plasticizer at ≤150℃ and mix.

[0051] S23. Add antioxidants at 140℃.

[0052] S24. Premix the organic bentonite with the remaining plasticizer into a slurry, add it to the base asphalt, and mix at a high speed of 4000 rpm for 60 minutes at 160℃-170℃. Then, mix at a low speed of 500 rpm-1000 rpm and cure for 1-2 hours to obtain the asphalt material.

[0053] S3. Preparation of filler material. The preparation process of filler material includes the following steps:

[0054] S31. Dry mix silicate cement, rice husk ash, fly ash, silica fume, sodium lignosulfonate, and coupling agent according to the mass ratio to obtain a uniform dry mix.

[0055] S32. Add water to the mixer at a water-to-binder ratio of 0.48-0.5, then add the dry mix to the mixer. First, mix at a low speed of 500 rpm-1000 rpm for 20 s-50 s, then mix at a high speed of 4000 rpm for 1 minute-3 minutes to obtain the filler material.

[0056] S4. Mix asphalt material with aggregates and compact them into a porous biomass asphalt mixture with interconnected pores; after cooling, inject filler material into the porous biomass asphalt mixture, and after solidification, a semi-flexible pavement is obtained.

[0057] Example 1

[0058] Preparation of modified soybean oil: Add 1000g of soybean oil to a three-necked flask and place it in a constant temperature water bath at 55℃. Add formic acid (100g) and concentrated sulfuric acid (3.5g), and start mechanical stirring (300-500rpm). Add 500g of 40% H2O2 to a dropping funnel and control the temperature at 50℃-60℃. Slowly add H2O2 (1-2 drops / second), maintain the reaction for 4 hours until the double bonds are basically converted, then stop heating, cool to room temperature, transfer to a separatory funnel, allow to stand and separate into layers, and collect the upper oil phase. Wash the oil phase with 5% Na2CO3 solution until neutral, 50mL each time, 2-3 times. Wash with hot deionized water (60℃) 3-4 times to remove residual salts, then add anhydrous sodium sulfate and stir to dehydrate (until clear and free of turbidity). Filter to remove sodium sulfate to obtain modified soybean oil.

[0059] Preparation of biomass asphalt mixture: 78.5% (by mass) of base asphalt was preheated to a fluid state. At ≤150℃, 8% (by mass) of modified soybean oil and 1.25% (by mass) of dibutyl phthalate plasticizer were added and mixed. Then, at 140℃, 1% (by mass) of type 2246 antioxidant was added. 10% (by mass) of organobentonite and the remaining 1.25% (by mass) of plasticizer were premixed into a slurry and added to the above mixture. The mixture was then subjected to high-speed shearing at 4000 rpm for 60 minutes at 160℃, followed by low-speed mixing at 1000 rpm for 2 hours to obtain asphalt. Biomass asphalt mixture was prepared by adding asphalt to the aggregate at an asphalt-aggregate ratio of 4.3%, with limestone as the aggregate.

[0060] Preparation of filler material: 64% by mass of ordinary Portland cement (PO 42.5) and 18% by mass of ultrafine rice husk ash (specific surface area 420 m²) were added. 2 The grouting material is prepared by dry mixing of 9% fly ash (Grade I), 6% silica fume, and 2% sodium lignosulfonate. Water is first added to the mixture in a high-speed mixer at a water-to-binder ratio of 0.49, followed by slow addition of the dry-mixed grouting material. The mixture is then stirred at a low speed of 700 rpm for 30 seconds, followed by the addition of 1% (by mass) silane coupling agent KH-550. Finally, the mixture is stirred at a high speed of 4000 rpm for 2 minutes to obtain the filling material.

[0061] Example 2

[0062] Preparation of modified soybean oil: 1000g of soybean oil was added to a three-necked flask and placed in a constant temperature water bath at 55℃. 110g of formic acid (11% of the soybean oil mass) and 4g of concentrated sulfuric acid (98% by mass) (0.4% of the soybean oil mass) were added, and mechanical stirring was started (400 rpm). 550g of 45% H2O2 (55% of the soybean oil mass) was added to a dropping funnel, and the temperature was maintained at 55℃. H2O2 was slowly added dropwise (approximately 2 hours), maintaining the reaction for 4.5 hours. Heating was stopped, and the mixture was cooled to room temperature. The mixture was transferred to a separatory funnel, allowed to stand for separation, and the upper oil phase was collected. The oil phase was washed three times with 5% Na2CO3 solution until neutral, 50mL each time. It was then washed three times with hot deionized water (60℃), anhydrous sodium sulfate was added, and the mixture was stirred to dehydrate. After filtration, epoxidized modified soybean oil (epoxide value ≥6%) was obtained.

[0063] Preparation of biomass asphalt mixture: 80% by weight of base asphalt is preheated to a fluid state. At ≤150℃, 10% by weight of modified soybean oil and 1% by weight of dibutyl phthalate are added and mixed. Then, at 140℃, 1% by weight of type 2246 antioxidant is added. 7% by weight of organobentonite and the remaining 1% by weight of dibutyl phthalate plasticizer are premixed into a slurry and added to the above mixture. The mixture is then stirred at 165℃ at 4000 rpm for 60 minutes under high-speed shearing, followed by low-speed stirring at 800 rpm for 1.5 hours to obtain asphalt aggregate. Biomass asphalt mixture is prepared by adding asphalt aggregate to the aggregate at an asphalt-aggregate ratio of 4.3%, with limestone as the aggregate.

[0064] Preparation of filler material: 60% by mass of ordinary Portland cement (PO 42.5), 20% by mass of ultrafine rice husk ash (specific surface area ≥ 420 m²) 2 The following ingredients were dry-mixed: 10% fly ash (Grade I), 5% silica fume, and 3% sodium lignosulfonate, to obtain a uniform dry mix. Water was added to a mixer at a water-to-binder ratio of 0.48, followed by the dry mix. The mixture was first stirred at a low speed of 800 rpm for 40 seconds, then 2% (by mass) of silane coupling agent (KH-550) was added, and finally stirred at a high speed of 4000 rpm for 2 minutes to obtain the filler material.

[0065] Example 3

[0066] Preparation of modified soybean oil: Same as in Example 1.

[0067] Preparation of biomass asphalt mixture: 76% (by mass) of base asphalt was preheated to a fluid state. Modified soybean oil (12% by mass) and dibutyl phthalate (1.25% by mass) were added at ≤150℃ and mixed. Then, 0.5% (by mass) of type 2246 antioxidant was added at 140℃. 9% (by mass) of organobentonite and the remaining 1.25% (by mass) of dibutyl phthalate plasticizer were premixed into a slurry and added to the above mixture. The mixture was then subjected to high-speed shearing at 4000 rpm at 170℃ for 60 minutes, followed by low-speed mixing at 500 rpm for 2 hours to obtain asphalt aggregate. Biomass asphalt mixture was prepared by adding asphalt aggregate to the aggregate at an asphalt-aggregate ratio of 4.3%, with limestone as the aggregate.

[0068] Preparation of filler material: 70% by weight of ordinary Portland cement (PO 42.5), 15% by weight of ultrafine rice husk ash (specific surface area ≥ 400 m²) 2The following ingredients were dry-mixed: 8% fly ash (Grade I), 5% silica fume, 1.5% sodium lignosulfonate, and 0.5% silane coupling agent (KH-550). Water was added at a water-to-binder ratio of 0.50. The mixture was first stirred at a low speed of 500 rpm for 50 seconds, and then stirred at a high speed of 4000 rpm for 3 minutes to obtain the filler material.

[0069] Comparative Example 1

[0070] In this comparative example, the biomass asphalt mixture was SBS modified asphalt. 95% of the same base as in Example 1 was preheated to 170°C, and then 5% of SBS modifier was added. The mixture was then subjected to high-speed shearing at 170°C and 4000 rpm for 60 minutes to obtain SBS modified asphalt.

[0071] Comparative Example 2

[0072] In this comparative example, ordinary cement-based grouting material was selected as the filling material. 100% ordinary Portland cement (PO 42.5) was used, with a water-cement ratio of 0.49, and the ordinary grouting material was prepared using the same mixing process as in Example 1.

[0073] Comparative Example 3

[0074] In this comparative example, the biomass asphalt mixture is a combination of ordinary soybean oil and organic bentonite.

[0075] Preparation of biomass asphalt mixture: 78.5% (by mass) of the same base as in Example 1 was preheated to a fluid state. At ≤150°C, 8% (by mass) of unmodified ordinary soybean oil and 1.25% (by mass) of dibutyl phthalate were added and mixed. Then, at 140°C, 1% (by mass) of type 2246 antioxidant was added. 10% (by mass) of organobentonite and the remaining 1.25% (by mass) of plasticizer were premixed into a slurry and added to the above mixture. The mixture was then subjected to high-speed shearing at 4000 rpm at 160°C for 60 minutes, followed by low-speed mixing at 1000 rpm for 2 hours to obtain the comparative asphalt mixture. Biomass asphalt mixture was prepared by adding asphalt to the aggregate at an asphalt-aggregate ratio of 4.3%, with limestone as the aggregate.

[0076] Preparation of filler material: 64% by mass of ordinary Portland cement (PO 42.5) and 22% by mass of ultrafine rice husk ash (specific surface area 420 m²) were added. 2 The following ingredients were dry-mixed: 11% fly ash (Grade I), 2% sodium lignosulfonate, and 1% silane coupling agent (KH-550). Water was added at a water-to-binder ratio of 0.49, and the mixture was first stirred at a low speed of 1000 rpm for 30 seconds, and then stirred at a high speed of 4000 rpm for 2 minutes to obtain the filler material.

[0077] Comparative Example 4

[0078] In this comparative example, the biomass asphalt mixture contains only organic bentonite and no modified soybean oil.

[0079] Preparation of biomass asphalt mixture: 86.5% (by mass) of the same base as in Example 1 was preheated to a fluid state. 1.25% (by mass) of dibutyl phthalate was added at ≤150°C and mixed. Then, 1% (by mass) of type 2246 antioxidant was added at 140°C. 10% (by mass) of organobentonite and the remaining 1.25% (by mass) of plasticizer were premixed into a slurry and added to the above mixture. The mixture was then sheared at 4000 rpm at 160°C for 60 minutes, followed by low-speed mixing at 1000 rpm for 2 hours to obtain the comparative asphalt mixture. Biomass asphalt mixture was prepared by adding asphalt to the aggregate at an asphalt-aggregate ratio of 4.3%, with limestone as the aggregate.

[0080] Preparation of filler material: 64% by mass of ordinary Portland cement (PO 42.5) and 33% by mass of ultrafine rice husk ash (specific surface area 420 m²) were added. 2 The filler material was dry-mixed with 2% sodium lignosulfonate and 1% silane coupling agent (KH-550) at a water-to-binder ratio of 0.49. The mixture was first stirred at 1000 rpm for 30 seconds, then at 4000 rpm for 2 minutes to obtain the filler material.

[0081] Semi-flexible pavement was prepared, and its performance was tested. The preparation method for the semi-flexible pavement was as follows: Marshall specimens were made using the biomass-asphalt mixture described in Example 1. The stability, porosity, interconnected porosity, segregation loss, and scattering loss of the Marshall specimens were tested. Specimens meeting the above requirements were subjected to density testing, and rutting slabs were prepared based on the density. After the rutting slabs cooled to room temperature for one day, the filler material from Example 1 was injected until no air bubbles were visible on the surface. Standard curing was performed for 7 days. The grouted rutting slabs were then cut into small beam specimens of 30mm × 35mm × 250mm. Dynamic stability at 60℃ and flexural strain at -10℃ were tested on the grouted rutting slabs and small beam specimens according to JTG E20-2011. The volume percentage of biomass-asphalt mixture in the rutting slabs was 75%, and the volume percentage of filler material was 25%.

[0082] The performance of the asphalt materials prepared in Examples 1-3, the SBS modified asphalt prepared in Comparative Example 1, and the asphalt materials prepared in Comparative Example 3 and Comparative Example 4 were tested, and the test results are shown in Table 1.

[0083] Table 1 Properties of Asphalt and SBS Modified Asphalt

[0084]

[0085] As shown in Table 1, the high-temperature stability and elastic recovery of asphalt were significantly improved after the modified soybean oil was compounded with organic bentonite, approaching or exceeding those of SBS modified asphalt. This meets the technical requirements of high-performance semi-flexible pavements and successfully realizes the partial replacement of petroleum-based polymers with bio-based materials.

[0086] The performance of the filler materials prepared in Examples 1-3 and Comparative Examples 2-4 was tested. The filler material specimens are as follows: Figure 2 As shown in the figure, the results are shown in Table 2.

[0087] Table 2. Properties of Filler Materials

[0088]

[0089] Table 2 shows that, while maintaining good workability, the filler materials in Examples 1-3 exhibited better stability (significantly reduced bleeding rate) and strength than ordinary cement paste. This is attributed to the micro-filling and pozzolanic effects of active admixtures such as ultrafine rice husk ash. The fluidity, stability, and strength of the filler material were significantly optimized after combining rice husk ash, fly ash, and silica fume.

[0090] The asphalt materials described in Examples 1-3 and Comparative Examples 1, 3, and 4 were combined with the filler materials described in Examples 1-3 and Comparative Example 2. Semi-flexible pavements with the same porosity were prepared according to the same asphalt-aggregate ratio and semi-flexible pavement preparation method as in Example 1. The performance of the semi-flexible pavements was tested, and the performance test results are shown in Table 3.

[0091] Table 3 Performance of Semi-Flexible Pavement

[0092]

[0093] The road surface performance of the various embodiments of the present invention is comparable to that of the petroleum-based system and significantly superior to that of the unmodified or single-material system, fully meeting the requirements for use on heavy-duty traffic pavements.

[0094] The bond performance between asphalt and filler materials was tested. The filler material from Example 1 was prepared into cubic specimens with dimensions of 40 mm × 40 mm × 40 mm. The asphalt material from Example 1 was uniformly coated onto the bonding surface of one specimen at a rate of 0.48 g. Immediately afterward, another filler material specimen was centered and bonded to it. A static load of 50 kg was applied to the top of the bond and maintained for 24 hours to ensure sufficient interface contact and promote bond curing. Bond strength testing was performed using a universal testing machine (UTM) with displacement control loading at a rate of 1 mm / min. The peak load at bond failure was recorded, and the bond strength was calculated.

[0095] Six sets of comparative tests were set up to compare the bonding performance:

[0096] (1) Adhesive specimens were prepared by using the asphalt material and the filler material described in Example 1 and by the above method.

[0097] (2) Using the asphalt material described in Example 1 and the filler material described in Comparative Example 2, specimens were prepared and tests were conducted using the same method as in Example 1.

[0098] (3) Using the SBS modified bitumen described in Comparative Example 1 and the filler material described in Example 1, specimens were prepared and tests were conducted using the same method as in Example 1.

[0099] (4) Using the SBS modified asphalt described in Comparative Example 1 and the filler material described in Comparative Example 2, specimens were prepared and tests were conducted using the same method as in Example 1 above.

[0100] (5) Using the asphalt material described in Comparative Example 3 and the filler material described in Example 1, specimens were prepared and tests were conducted using the same method as in Example 1.

[0101] (6) Using the asphalt material described in Comparative Example 4 and the filler material described in Example 1, specimens were prepared and tests were conducted using the same method as in Example 1.

[0102] The results of the interfacial bonding performance between asphalt and filler materials are shown in Table 4.

[0103] Table 4. Adhesion performance test results

[0104]

[0105] Table 4 shows that using only the biomass bitumen mixture and filler material from Example 1 does not achieve optimal interfacial strength. Only by using both the biomass bitumen mixture and filler material from Example 1 can a stable and high-strength interface (strength reaching 2.48 MPa) be formed, solving the industry problem of poor compatibility between bio-based materials and inorganic materials.

[0106] Therefore, the biomass low-carbon semi-flexible pavement and its preparation method described in this invention can solve the problems of low load capacity, poor low-temperature crack resistance and poor durability of existing biomass semi-flexible pavements.

[0107] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. 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 still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A biomass low-carbon semi-flexible pavement, characterized in that: The mixture comprises 72%-84% biomass asphalt mixture by volume and 16%-28% filler material; the asphalt-aggregate ratio of the biomass asphalt mixture is 4%-5%; the asphalt component in the biomass asphalt mixture includes the following components by mass percentage: base asphalt 74%-83%, modified soybean oil 8%-12%, organic bentonite 7%-10%, plasticizer 1.5%-3.5%, and antioxidant 0.5%-1.5%; the filler material includes the following components by mass percentage: silicate cement 58%-70%, rice husk ash 15%-20%, fly ash 8%-10%, silica fume 5%-6%, sodium lignosulfonate 1.5%-3.5%, and coupling agent 0.5%-1.5%; The modified soybean oil is epoxidized soybean oil, and the epoxy value of the epoxidized soybean oil is... 6%; The specific surface area of ​​the rice husk ash is not less than 400 m². 2 / kg.

2. The biomass low-carbon semi-flexible pavement according to claim 1, characterized in that: The plasticizer is dibutyl phthalate, the antioxidant is 2264, and the silane coupling agent is KH-550.

3. The biomass low-carbon semi-flexible pavement according to claim 1, characterized in that: The water-cement ratio of the filler material is 0.48-0.

5.

4. A method for preparing a biomass low-carbon semi-flexible pavement according to any one of claims 1-3, characterized in that, Includes the following steps: S1. Preparation of modified soybean oil: Soybean oil is mixed with formic acid and concentrated sulfuric acid at 50℃-60℃ until homogeneous. While stirring, hydrogen peroxide with a mass concentration of 30%-50% is added dropwise. After the reaction, the mixture is purified by separation. The oil phase is washed with 5% Na2CO3 solution until neutral. After washing with hot deionized water, anhydrous sodium sulfate is added and stirred to dehydrate. After filtration, modified soybean oil is obtained. S2, Preparation of asphalt material; S3. Preparation of filler material; S4. Mix the asphalt material with the aggregate and compact it into a porous biomass asphalt mixture with interconnected pores. After cooling, the filler material is injected into the porous biomass asphalt mixture, and after solidification, a semi-flexible pavement is obtained.

5. The method for preparing a biomass low-carbon semi-flexible pavement according to claim 4, characterized in that: In step S1, the amount of formic acid is 8%-12% of the soybean oil mass, the mass fraction of concentrated sulfuric acid is 95%-98%, the amount of concentrated sulfuric acid is 0.2%-0.5% of the soybean oil mass, the amount of hydrogen peroxide is 40%-60% of the soybean oil mass, and the reaction time is 3-5 hours.

6. The method for preparing a biomass low-carbon semi-flexible pavement according to claim 4, characterized in that, In step S2, the preparation process of the asphalt material includes the following steps: S21. Preheat the base asphalt to a fluid state; S22. Add modified soybean oil and half of the plasticizer at ≤150℃ and mix. S23. Add antioxidants at 140℃; S24. Premix the organic bentonite with the remaining plasticizer into a slurry, add it to the base asphalt, and mix at a high speed of 4000 rpm for 60 minutes at 160℃-170℃. Then, mix at a low speed of 500 rpm-1000 rpm and cure for 1-2 hours to obtain the biomass asphalt mixture.

7. The method for preparing a biomass low-carbon semi-flexible pavement according to claim 4, characterized in that, In step S3, the preparation process of the filler material includes the following steps: S31. Dry mix silicate cement, rice husk ash, fly ash, silica fume, sodium lignosulfonate, and coupling agent according to the mass ratio to obtain a uniform dry mix. S32. Add water to the mixer at a water-to-binder ratio of 0.48-0.5, then add the dry mix to the mixer. First, mix at a low speed of 500-1000 rpm for 20-50 seconds, then mix at a high speed of 4000 rpm for 1-3 minutes to obtain the filler material.

8. The method for preparing a biomass low-carbon semi-flexible pavement according to claim 4, characterized in that: The biomass asphalt mixture has a penetration of 60-80 at 25°C, a softening point ≥75°C, and a kinematic viscosity of 1.8 at 135°C. -3.0 The elastic recovery rate at 25℃ is ≥85%; The initial flowability of the filler material is 10 s-14 s, the flowability at 30 min is ≤18 s, the water bleeding rate at 3 h is ≤0.01%, and the compressive strength at 7 days is ≥15 MPa. The interfacial strength between biomass asphalt mixture and filler material is ≥2.15 MPa, the dynamic stability is ≥26,000 cycles / mm, and the bending tensile strain at -10℃ is ≥3,200 με.

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