Composite modified bio-based hydraulic asphalt concrete and preparation method thereof

Abstract

The invention discloses composite modified bio-based hydraulic asphalt concrete and a preparation method thereof, and belongs to the technical field of hydraulic engineering materials. The concrete is prepared from 8 to 12 parts of asphalt binder, 50 to 65 parts of basalt-quartzite composite coarse aggregate, 20 to 35 parts of machine-made sand-rubber powder fine aggregate, 5 to 10 parts of mineral filler, 0.5 to 3 parts of composite modifier, 0.8 to 1.2 parts of warm mixing agent and 0.5 to 1.5 parts of organosilicon waterproofing agent. Waste vegetable oil is innovatively adopted to be subjected to epoxidation treatment to prepare a bio-based regenerated asphalt plasticizer (the epoxy value is 4.5-6.0%), the bio-based regenerated asphalt plasticizer, nano silicon dioxide and polyester fibers are compounded according to the ratio of (1-3): (2-4): (0.5-1.5) to form a synergistic modification system, and the mixing temperature is reduced by 20-30 DEG C in combination with an alkylamine salt / fatty acid amide warm mixing agent. Through basalt-quartzite (7-9: 1-3) discontinuous grading design and rubber powder (3-8%) elasticity enhancement, the product has high rutting resistance (dynamic stability is greater than or equal to 4200 times / mm), excellent low-temperature crack resistance (bending strain is greater than or equal to 2900 mu epsilon) and environmental protection characteristics, carbon emission is reduced by 60%, the quartzite utilization rate reaches 30%, and the product is suitable for green road engineering construction.

Description

Technical Field

[0001] The present invention belongs to the technical field of water conservancy engineering materials, and particularly relates to a composite modified bio-based hydraulic asphalt concrete and a preparation method thereof. Background Art

[0002] As an important anti-seepage material, hydraulic asphalt concrete is widely used in the fields of water conservancy projects, road construction, etc. Traditional hydraulic asphalt concrete is usually prepared with petroleum asphalt as the binder, together with aggregates and fillers. However, with the enhancement of environmental awareness and the promotion of the concept of sustainable development, traditional petroleum-based asphalt concrete faces some challenges.

[0003] Firstly, the production of petroleum asphalt relies on limited petroleum resources, and its non-renewability does not meet the current requirements of resource conservation. In addition, petroleum asphalt will generate high carbon emissions and harmful gases during production and use, causing a greater impact on the environment. Therefore, developing a more environmentally friendly and sustainable asphalt concrete material has become an urgent need for the industry's development.

[0004] Secondly, the performance of traditional hydraulic asphalt concrete under high-temperature and low-temperature environments still needs to be improved. Under high-temperature conditions, asphalt concrete is prone to diseases such as rutting, while under low-temperature environments, cracks may occur, affecting its durability and service life. Therefore, how to improve the high and low temperature performance of hydraulic asphalt concrete through material modification is one of the important research directions at present.

[0005] In addition, although the existing warm mix technology can reduce the mixing temperature to a certain extent, reduce energy consumption and carbon emissions, there are still some problems in actual applications, such as the stability and adaptability of warm mix agents are not ideal enough, and the improvement of material performance is limited.

[0006] In view of the above problems, the present invention proposes a composite modified bio-based hydraulic asphalt concrete and a preparation method thereof, aiming to realize the replacement of petroleum-based plasticizers with waste vegetable oil derivatives through innovative component design and process optimization, and improve the resource recycling rate; through the synergistic effect of nano-silica, polyester fiber and bio-based plasticizer, improve the high and low temperature performance and durability of hydraulic asphalt concrete; combine warm mix technology with the utilization of steel slag and rubber powder solid waste to reduce the mixing temperature and carbon emissions, and provide a high-performance and environmentally friendly material solution for water conservancy project construction. Summary of the Invention

[0007] The present invention aims to provide a composite modified bio-based hydraulic asphalt concrete and its preparation method. Through innovative component design and process optimization, the following objectives are achieved: using waste vegetable oil derivatives to replace petroleum-based plasticizers to improve the resource recycling rate; through the synergistic effect of nano-silica, polyester fiber, and bio-based plasticizer, improving the high and low temperature performance and durability of hydraulic asphalt concrete; combining warm mix technology with the utilization of solid wastes such as quartzite and rubber powder to reduce the mixing temperature by 20 - 30 °C and reduce carbon emissions.

[0008] The present invention provides a composite modified bio-based hydraulic asphalt concrete, which includes the following components by mass: 8 - 12 parts of asphalt binder, 50 - 65 parts of coarse aggregate, 20 - 35 parts of fine aggregate, 5 - 10 parts of mineral filler, 0.5 - 3 parts of composite modifier, 0.8 - 1.2 parts of warm mix agent, and 0.5 - 1.5 parts of silicone waterproof agent;

[0009] The composite modifier is composed of nano-silica, bio-based recycled asphalt plasticizer, and polyester fiber in a mass ratio of (1 - 3):(2 - 4):1;

[0010] The bio-based recycled asphalt plasticizer is a derivative of waste vegetable oil treated by epoxidation.

[0011] Furthermore, the coarse aggregate is a mixed aggregate of basalt and quartzite, and the mass ratio of the two is (7 - 9):2. The particle size range of the coarse aggregate is 4.75 - 16 mm, and it adopts a gap-graded design, with the passing rate of the 9.5 mm sieve hole being 55 - 65%.

[0012] Furthermore, the fine aggregate includes a compound combination of manufactured sand and rubber powder, and the rubber powder content is 3 - 8% of the total mass of the fine aggregate, with a particle size of 0.3 - 1.18 mm.

[0013] Furthermore, the mineral filler of the asphalt binder is selected from one or more of: limestone powder, slag powder, silica fume, fly ash, bentonite, talc powder, kaolin, or industrial by-product gypsum powder, with a particle size ≤ 0.075 mm, and its median particle size (D50) is 5 - 20 μm.

[0014] Furthermore, it is selected from one or more of: petroleum asphalt, modified asphalt (SBS, SBR, EVA modified), natural asphalt, and rubber asphalt.

[0015] Furthermore, the preparation method of the bio-based recycled asphalt plasticizer is as follows:

[0016] 1) Centrifugally filter the waste cooking vegetable oil to remove mechanical impurities, add 2 - 5% of activated clay based on the mass of the waste vegetable oil, stir and decolorize at 80 - 100 °C for 30 minutes, and then remove free fatty acids by distillation to make the acid value ≤ 1 mg KOH / g;

[0017] 2) Heat the pretreated waste vegetable oil to 60 - 70 °C, and successively add formic acid accounting for 3 - 6% of the mass of the waste vegetable oil, concentrated sulfuric acid accounting for 0.5 - 1.5%, 30% hydrogen peroxide accounting for 5 - 10% under the atmosphere of inert gas, react for 4 - 6 hours, and control the epoxy value to be 4.5 - 6.0%;

[0018] 3) Add a 5% sodium carbonate solution by mass to the reaction product to adjust the pH to 6 - 7. After separating and removing the aqueous phase, wash with deionized water until the conductivity ≤ 50 μS / cm;

[0019] 4) Dry the product under a vacuum of -0.08 MPa at 90 °C for 2 hours to obtain an epoxidized derivative with a water content ≤ 0.1%.

[0020] Furthermore, the warm mix additive is a composite system composed of an alkylamine salt - type surfactant and a fatty acid amide in a mass ratio of 1:2. The addition temperature is 50 - 60 °C, and after addition, the mixing temperature of the mixture is reduced by 20 - 30 °C.

[0021] Furthermore, the alkylamine salt - type surfactant is selected from one or more of: octadecylamine acetate, coconut amine acetate, oleylamine hydrochloride, and hydrogenated tallow amine hydrochloride.

[0022] Furthermore, the preferred alkylamine salt - type surfactant is: octadecylamine acetate or coconut amine acetate.

[0023] Furthermore, the preferred warm mix additive is: a composite system composed of octadecylamine acetate and a fatty acid amide in a mass ratio of 1:2. The addition temperature is 50 - 60 °C, and after addition, the mixing temperature of the mixture is reduced by 20 - 30 °C.

[0024] Furthermore, the preparation method of the composite modifier is: mix the nano - silica, the bio - based recycled asphalt plasticizer, and the polyester fiber in a mass ratio of (1 - 3):(2 - 4):1, stir for 4 - 6 h, maintain at 60 - 65 °C for the first 2 hours, raise the temperature to 70 °C in the subsequent 2 - 4 hours, and cool to room temperature to obtain the composite modifier.

[0025] A preparation method of a composite - modified bio - based hydraulic asphalt concrete, comprising the following steps:

[0026] Heat the asphalt binder to 140 - 150 °C, successively add the composite modifier and the warm mix additive, stir evenly at 50 - 60 °C, add the coarse aggregate, the fine aggregate, the mineral filler, and the silicone waterproof agent, mix at 110 - 130 °C for 3 - 5 minutes, compact and form the mixture at 120 - 135 °C, and cool to room temperature to obtain the finished product.

[0027] Furthermore, an intermittent mixing process is adopted during the mixing process: first, add the coarse aggregate and 50% of the asphalt mixture and premix for 1 minute, and then add the fine aggregate, the mineral filler and the remaining asphalt mixture and mix for 2 - 4 minutes.

[0028] Furthermore, the composite modified bio-based hydraulic asphalt concrete is applied to hydraulic building materials.

[0029] Through the quantum confinement effect and surface activity, nano-silica forms a uniformly dispersed nano-network structure in the asphalt matrix, significantly improving the anti-aging property and thermal stability. Its high specific surface area (about 200 - 300 m² / g) enhances the interfacial bonding force between the asphalt and the aggregate, reducing the high-temperature flow deformation; at the same time, functional groups such as hydroxyl and carboxyl groups on the surface of the nano-particles chemically adsorb or crosslink with the polar components of the asphalt to form a stable "core-shell" structure, inhibiting the excessive softening of the colloid.

[0030] The bio-based recycled asphalt plasticizer (epoxidized waste vegetable oil) adds to the unsaturated hydrocarbons of the asphalt through the epoxide group (epoxy value 4.5 - 6.0%), reducing the glass transition temperature and endowing low-temperature ductility; the pretreatment process (acid value ≤1mg KOH / g) removes impurities, improves the compatibility with the asphalt, and reduces the risk of interfacial separation.

[0031] The polyester fiber forms a three-dimensional network structure. The rigid main chain restricts the flow of the asphalt, and the flexible side chain disperses the stress wave, significantly improving the crack resistance and impact resistance. Its orientation distribution can absorb the load stress and delay the crack propagation, forming a multi-level reinforcement system with nano-silica and bio-based recycled asphalt plasticizer, and synergistically achieving high-temperature stability (the softening point is increased by 25%) and low-temperature crack resistance (the embrittlement temperature is decreased by 40%).

[0032] After the alkylamine salt (such as octadecylamine acetate) is compounded with the fatty acid amide, the hydrophobic end adsorbs on the surface of the asphalt, and the hydrophilic end reduces the interfacial tension (the contact angle is reduced by 30 - 50%), promoting low-temperature dispersion and reducing the mixing energy consumption (the temperature is reduced by 20 - 30℃).

[0033] The warm mix agent molecules form a reversible physical adsorption layer in the asphalt, inhibiting the aggregation of the colloid through the steric hindrance effect and maintaining a low flow viscosity (40% lower than that of the traditional asphalt). When the addition temperature is accurately controlled at 50 - 60℃, the dispersion is accelerated, and the adsorption layer is reorganized after cooling to ensure durability.

[0034] The low-temperature mixing process reduces the carbon emissions by 60% and avoids the formation of polycyclic aromatic hydrocarbons due to high-temperature oxidation; the warm mix agent system (compounded at 1:2) has both high efficiency and thermal stability, maintaining the rheological properties during the compaction stage (120 - 135℃) to ensure that the construction efficiency and material properties are not damaged.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] 1. The present invention realizes a double breakthrough in the resource utilization of waste oils (acid value ≤ 1 mg KOH / g, epoxy value 4.5 - 6.0%) and the improvement of material properties by innovatively constructing a ternary synergistic system of bio-based regenerated asphalt plasticizer - nano-silica - polyester fiber. In the composite modifier, nano-silica enhances the anti-aging property through the quantum confinement effect, the bio-based regenerated asphalt plasticizer provides flexibility improvement, and the polyester fiber forms a three-dimensional network structure to strengthen the mechanical properties. The synergy of the three increases the high-temperature stability of the asphalt mixture by 25% and the low-temperature crack resistance by 40%, and the carbon emissions during the production process are reduced by 45% compared with the traditional process.

[0037] 2. In terms of the innovation of the aggregate system, the basalt - quartzite composite coarse aggregate (mass ratio 7 - 9:2) optimizes the density through the gap-graded design (the passing rate of the 9.5 mm sieve hole is 55 - 65%), and the compressive strength is increased by 18% compared with the single basalt aggregate. The incorporation of quartzite reduces the raw material cost by 20% and improves the water stability; the fine aggregate adopts the mechanism sand - rubber powder compound system (the rubber powder content is 3 - 8%), and uses the elastic deformation characteristics of rubber particles to improve the impact resistance (the improvement rate of the dynamic modulus is 32%), taking into account functionality and environmental protection.

[0038] 3. Through the staged temperature-controlled mixing (60 - 65°C for the first 2 hours + 70°C for the next 2 - 4 hours) and the batch mixing process (the coarse aggregate is pre-mixed for 1 minute + the total mixing is 2 - 4 minutes), the material dispersion uniformity ≥ 95% and no segregation phenomenon are achieved, and the preparation cycle is shortened by 30%. The warm mix additive system adopts the compounding technology of alkylamine salts (octadecylamine acetate / coconut amine acetate) and fatty acid amides at a ratio of 1:2, and reduces the mixing temperature by 20 - 30°C (the energy-saving efficiency is increased by 40%) at the addition temperature of 50 - 60°C. The final product has both high strength (Marshall stability ≥ 18 kN), high durability (the mass loss after 50 freeze-thaw cycles < 5%) and low carbon emission characteristics (CO2 emission reduction of 60%), and is suitable for the field of green base materials. Detailed implementation manners

[0039] The technical solutions of the present invention will be described clearly and completely below. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0040] In this invention, the petroleum asphalt is purchased from: Shandong Shengteng Chemical Co., Ltd., the basalt is purchased from: Qingyuan Manchu Autonomous County Shuangqi Quarry Co., Ltd., the quartzite is purchased from: MCC Baosteel Technical Services Co., Ltd., the manufactured sand is purchased from: Wuhan Deyi Environmental Protection New Materials Co., Ltd., the rubber powder is purchased from: Hengshui Zehao Rubber Chemical Co., Ltd., the limestone powder is purchased from: Huzhou Lanyun Ore Powder Co., Ltd., the nano-silica is purchased from: Shanghai Aladdin Biochemical Technology Co., Ltd., the polyester fiber is purchased from: Hubei Longxin Chemical Industry Co., Ltd., the octadecylamine acetate is purchased from: Shanghai Aladdin Biochemical Technology Co., Ltd., the fatty acid amide is purchased from: Wuhan Kamike Technology Co., Ltd., and the silicone waterproof agent is purchased from: Guangxi Qinglong Chemical Building Materials Co., Ltd.

[0041] Further, for the composite modified bio-based hydraulic asphalt concrete, the asphalt binder includes, by mass: 8 parts, 9 parts, 10 parts, 11 parts, 12 parts;

[0042] The coarse aggregate includes, by mass: 50 parts, 51 parts, 52 parts, 53 parts, 54 parts, 55 parts, 56 parts, 57 parts, 58 parts, 59 parts, 60 parts, 61 parts, 62 parts, 63 parts, 64 parts, 65 parts;

[0043] The fine aggregate includes, by mass: 20 parts, 21 parts, 22 parts, 23 parts, 24 parts, 25 parts, 26 parts, 27 parts, 28 parts, 29 parts, 30 parts, 31 parts, 32 parts, 33 parts, 34 parts, 35 parts;

[0044] The mineral filler includes, by mass: 5 parts, 6 parts, 7 parts, 8 parts, 9 parts, 10 parts;

[0045] The composite modifier includes, by mass: 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts, 1.6 parts, 1.7 parts, 1.8 parts, 1.9 parts, 2.0 parts, 2.1 parts, 2.2 parts, 2.3 parts, 2.4 parts, 2.5 parts, 2.6 parts, 2.7 parts, 2.8 parts, 2.9 parts, 3.0 parts;

[0046] The warm mix additive includes, by mass: 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts;

[0047] The silicone waterproof agent includes, by mass: 0.5 parts, 0.6 parts, 0.7 parts, 0.8 parts, 0.9 parts, 1.0 parts, 1.1 parts, 1.2 parts, 1.3 parts, 1.4 parts, 1.5 parts.

[0048] It should be noted that the company name "Shanghai Aladdin Biochemical Technology Co., Ltd." in the translation is for reference only, and you can adjust it according to the actual situation.Further, the composite modifier consists of nano-silica, bio-based recycled asphalt plasticizer, and polyester fiber in a mass ratio of 1:2:1, 1:3:1, 1:4:1, 2:2:1, 2:3:1, 2:4:1, 3:2:1, 3:3:1, 3:4:1.

[0049] Further, the coarse aggregate is a mixed aggregate of basalt and quartzite, and the mass ratio of the two is 7:2, 8:2, 9:2.

[0050] Further, the dosage of the rubber powder is 3%, 4%, 5%, 6%, 7%, 8% of the total mass of the fine aggregate.

[0051] Example 1-1

[0052] Preparation of a bio-based recycled asphalt plasticizer.

[0053] P1. Centrifuge and filter the waste vegetable oil to remove mechanical impurities, add activated clay accounting for 3% of the mass of the waste vegetable oil, stir and decolorize at 90 °C for 30 minutes, and distill to remove free fatty acids to make the acid value ≤ 1 mg KOH / g;

[0054] P2. Heat the pretreated waste vegetable oil to 65 °C, and successively add formic acid accounting for 4% of the mass of the waste vegetable oil, concentrated sulfuric acid accounting for 1%, and 30% hydrogen peroxide accounting for 8%. Under an inert atmosphere, react for 5 hours and control the epoxy value to be 5.0%;

[0055] P3. Adjust the pH of the reaction product to 6-7. After separating and removing the aqueous phase, wash with deionized water until the conductivity ≤ 50 μS / cm. After drying the product, the bio-based recycled asphalt plasticizer with a water content ≤ 0.1% is obtained.

[0056] Example 1-2

[0057] Preparation of a composite modifier.

[0058] Mix the nano-silica, the bio-based recycled asphalt plasticizer (the bio-based recycled asphalt plasticizer prepared in Example 1-1), and the polyester fiber in a mass ratio of 2:3:1, stir for 5 h, maintain at 65 °C for the first 2 hours, and raise the temperature to 70 °C in the subsequent 2-4 hours, and cool to room temperature to obtain the composite modifier.

[0059] Example 1-3

[0060] Preparation of a composite modifier.

[0061] Mix the nano-silica, the bio-based recycled asphalt plasticizer (the bio-based recycled asphalt plasticizer prepared in Example 1-1), and the polyester fiber in a mass ratio of 1:4:1, stir for 5 h, maintain at 65 °C for the first 2 hours, heat up to 70 °C in the subsequent 2 - 4 hours, and cool to room temperature to obtain the composite modifier.

[0062] Example 1

[0063] The preparation method of the composite modified bio-based hydraulic asphalt concrete prepared in this example is as follows: Weigh 10 parts of petroleum asphalt, 60 parts of the mixed coarse aggregate of basalt and quartzite (mass ratio 8:2) (particle size 4.75 - 16 mm, passing rate of 9.5 mm sieve hole 60%), 30 parts of the compound fine aggregate of manufactured sand and rubber powder (rubber powder content 5%, particle size 0.3 - 1.18 mm), 8 parts of limestone powder, 1.8 parts of the composite modifier (nano-silica: bio-based recycled asphalt plasticizer: polyester fiber = 2:3:1, the composite modifier prepared in Example 1-2), 1.0 part of the warm mix additive (octadecylamine acetate and fatty acid amide 1:2), and 1.0 part of the silicone waterproofing agent. The pre-treated waste cooking vegetable oil is epoxidized (epoxy value 5.2%) to obtain the bio-based recycled asphalt plasticizer, and is mixed with nano-silica and polyester fiber at 65 °C for 3 hours. After heating the asphalt to 145 °C, the modifier and the warm mix additive are added and stirred for 12 minutes. The aggregate, filler, and silicone waterproofing agent are added in two batches and mixed at 120 °C for 4 minutes. The final compaction temperature is 130 °C to prepare the hydraulic asphalt concrete.

[0064] Example 2

[0065] The preparation method of the composite modified bio-based hydraulic asphalt concrete prepared in this example refers to the preparation method of Example 1, and the ratio of the composite modifier is adjusted to nano-silica: bio-based recycled asphalt plasticizer: polyester fiber = 1:4:1 (the composite modifier prepared in Example 1-3), the addition amount of the warm mix additive is increased to 1.2 parts, the coarse aggregate is basalt: quartzite = 7:3, the rubber powder content in the fine aggregate is 8%, the mixing temperature is reduced to 115 °C, and the rest is the same as the preparation method of Example 1.

[0066] Comparative Example 1

[0067] The preparation method of the hydraulic asphalt concrete prepared in this comparative example refers to the preparation method of Example 1, the bio-based recycled asphalt plasticizer is cancelled, and an equal amount of petroleum-based aromatic oil is used instead, and the rest is the same as Example 1.

[0068] Comparative Example 2

[0069] The preparation method of the hydraulic asphalt concrete prepared in this comparative example refers to the preparation method of Example 1, the warm mix additive is omitted and the mixing temperature is restored to 160 °C, and the rest is the same as Example 1.

[0070] Comparative Example 3

[0071] For the hydraulic asphalt concrete prepared in this comparative example, referring to the preparation method of Example 1, the coarse aggregate was changed to single basalt (quartzite content 0%), the rubber powder was removed from the fine aggregate, and the rest was the same as Example 1.

[0072] Comparative Example 4

[0073] For the hydraulic asphalt concrete prepared in this comparative example, referring to the preparation method of Example 1, polyester fiber was removed from the composite modifier, and the ratio of nano-silica to bio-based recycled asphalt plasticizer was adjusted to 3:5, and the rest was the same as Example 1.

[0074] Performance test:

[0075] Test according to the JTG E20-2011 standard.

[0076] 。

[0077] In terms of material property optimization, the composite modifier system (nano-silica, bio-based recycled asphalt plasticizer and polyester fiber) significantly improved the high and low temperature performance of hydraulic asphalt concrete through synergistic effects. Among them, the combination of nano-silica (2 parts) and bio-based recycled asphalt plasticizer modified with waste cooking oil increased the dynamic stability to 4860 times / mm, a 38% increase compared with the traditional petroleum-based plasticizer system, and the incorporation of polyester fiber increased the flexural failure strain by 22% through three-dimensional network reinforcement. At the same time, under the premise of reducing the mixing temperature to 120°C by applying warm mixing technology, through the synergistic viscosity reduction effect of octadecylamine acetate and fatty acid amide, not only a high immersion stability of 94.2% was maintained, but also asphalt aging caused by high temperature mixing was reduced, and the flow value was optimized to 34 (0.1mm), and the void ratio of the mixture was reduced by 0.8 percentage points compared with the conventional 160°C process.

[0078] The solid waste resource utilization strategy demonstrated multiple technical advantages: replacing 20% of the basalt coarse aggregate with quartzite increased the freeze-thaw splitting strength ratio by 17.6%, and its surface porous structure enhanced the aggregate-asphalt interface bonding force; the incorporation of 5-8% rubber powder increased the low temperature crack resistance by 34.3%, effectively alleviating the environmental pressure of waste tires. In terms of environmental benefits, the bio-based recycled asphalt plasticizer reduced the VOC emissions by 63%. Combining the synergistic utilization of quartzite and rubber powder, the consumption of natural aggregates was reduced by 42%, and the overall solid waste utilization rate reached 87%. On the basis of meeting the core performance standards of dynamic stability > 4000 times / mm and freeze-thaw splitting ratio > 85%, this system achieved a balance between low-carbon preparation and high-value utilization of solid waste, providing a promotable industrial solution for the development of green materials.

[0079] Although embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A composite modified bio-based hydraulic asphalt concrete, characterized in that, The composite modified bio-based hydraulic asphalt concrete comprises the following components by mass: 8-12 parts of asphalt binder, 50-65 parts of coarse aggregate, 20-35 parts of fine aggregate, 5-10 parts of mineral filler, 0.5-3 parts of composite modifier, 0.8-1.2 parts of warm mix agent, and 0.5-1.5 parts of silicone waterproof agent; The composite modifier consists of nano-silica, bio-based recycled asphalt plasticizer and polyester fiber in a mass ratio of (1-3):(2-4):1; The bio-based recycled asphalt plasticizer is obtained by epoxidizing waste vegetable oil.

2. The composite modified bio-based hydraulic asphalt concrete according to claim 1, wherein The coarse aggregate is a mixed aggregate of basalt and quartzite, and the mass ratio of the two is (7-9):

2. The particle size range of the coarse aggregate is 4.75-16 mm, and the passing rate of the 9.5 mm sieve hole is 55-65%.

3. A composite modified bio-based hydraulic asphalt concrete according to claim 1, characterized in that, The fine aggregate comprises a compound combination of manufactured sand and rubber powder. The dosage of the rubber powder is 3-8% of the total mass of the fine aggregate, and the particle size of the fine aggregate is 0.3-1.18 mm.

4. A composite modified bio-based hydraulic asphalt concrete according to claim 1, wherein, The preparation method of the bio-based recycled asphalt plasticizer comprises: Centrifugally filtering the waste vegetable oil to remove mechanical impurities, adding 2-5% of activated clay by mass of the waste vegetable oil, stirring and decolorizing at 80-100 °C for 30 minutes, distilling to remove free fatty acids, and making the acid value ≤ 1 mg KOH / g; Heating the pretreated waste vegetable oil to 60-70 °C, sequentially adding 3-6% of formic acid, 0.5-1.5% of concentrated sulfuric acid, and 5-10% of 30% hydrogen peroxide by mass of the waste vegetable oil, reacting for 4-6 hours under an inert atmosphere, and controlling the epoxy value to be 4.5-6.0%; Adjusting the pH of the reaction product to 6-7, separating and removing the aqueous phase, washing with deionized water until the conductivity ≤ 50 μS / cm, and drying the product to obtain the bio-based recycled asphalt plasticizer with a water content ≤ 0.1%.

5. A composite modified bio-based hydraulic asphalt concrete according to claim 1, characterized in that, The warm mix agent is composed of an alkylamine salt type surfactant and a fatty acid amide in a mass ratio of 1:

2.

6. The composite modified bio-based hydraulic asphalt concrete according to claim 5, characterized in that, The alkylamine salt type surfactant is selected from one or more of octadecylamine acetate, coconut amine acetate, oleylamine hydrochloride, and hydrogenated tallow amine hydrochloride.

7. A composite modified bio-based hydraulic asphalt concrete according to claim 1, characterized in that, The preparation method of the composite modifier is: mixing the nano-silica, the bio-based recycled asphalt plasticizer and the polyester fiber in a mass ratio of (1-3):(2-4):1, stirring for 4-6 h, maintaining at 60-65 °C for the first 2 hours, heating to 70 °C in the next 2-4 hours, and cooling to room temperature to obtain the composite modifier.

8. A preparation method of the composite modified bio-based hydraulic asphalt concrete according to any one of claims 1-7, characterized in that, Comprising the following steps: Heating the asphalt binder to 140-150 °C, sequentially adding the composite modifier and the warm mix agent, stirring evenly at 50-60 °C, adding the coarse aggregate, the fine aggregate, the mineral filler and the silicone waterproof agent, mixing at 110-130 °C for 3-5 minutes, compacting and molding the mixture at 120-135 °C, and cooling to room temperature to obtain the finished product.

9. The preparation method of a composite modified bio-based hydraulic asphalt concrete according to claim 8, characterized in that, During the mixing process, an intermittent mixing process is adopted: first adding the coarse aggregate and 50% of the asphalt mixture and premixing for 1 minute, and then adding the fine aggregate, the mineral filler and the remaining asphalt mixture and mixing for 2-4 minutes.

10. The composite modified bio-based hydraulic asphalt concrete according to any one of claims 1-6 is applied in hydraulic building materials.