Rice husk charcoal-SBS composite modified asphalt mixture and preparation method thereof

Abstract

The invention discloses a rice husk charcoal-SBS composite modified asphalt mixture and a preparation method, and belongs to the technical field of modified asphalt, the preparation method comprises the following steps: step (1) heating matrix asphalt in a drying oven to a completely molten state; (2) adding the rice husk charcoal powder into the matrix asphalt and stirring; (3) transferring the mixture of the rice husk charcoal and the matrix asphalt into a shearing machine for high-speed shearing; (4) adding an SBS modifier into the mixture of the rice husk charcoal and the matrix asphalt; (5) adding sulfur into the mixture; (6) stirring the mixture, and discharging bubbles in the mixture to prepare rice husk charcoal-SBS composite modified asphalt; (7) carrying out dry mixing on the aggregate, adding the prepared rice husk charcoal-SBS composite modified asphalt, and stirring; and (8) adding mineral powder, and stirring to obtain the rice husk charcoal-SBS composite modified asphalt mixture. According to the invention, the problem of defects of SBS modified asphalt in engineering application in the prior art is solved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of modified asphalt, in particular to a rice husk carbon-SBS composite modified asphalt mixture and a preparation method thereof. BACKGROUND

[0002] With the continuous development of economy and the continuous improvement of transportation infrastructure, the mileage of highways is also steadily increasing, which puts higher requirements on the material performance of road engineering. As the main material for building highways, the performance of asphalt is greatly affected by temperature changes. In high temperature environment, rutting easily occurs, and in low temperature environment, cracking and aging problems occur.

[0003] Currently, SBS modified asphalt is widely used in asphalt pavement engineering due to its excellent high and low temperature performance and aging resistance. Although SBS modified asphalt has significant advantages in performance improvement, there are still defects in actual engineering application, such as phase separation of SBS during high-temperature storage, which leads to sedimentation or stratification of polymers in asphalt, affecting the consistency of the material and the construction quality, and the production cost of SBS modified asphalt is high, and the price fluctuates greatly, which is not conducive to large-scale engineering promotion. SUMMARY

[0004] The purpose of the present application is to provide a rice husk carbon-SBS composite modified asphalt mixture and a preparation method thereof to solve the defects of SBS modified asphalt in engineering application in the prior art.

[0005] To achieve the above-mentioned purpose, the present application provides the following technical scheme: a preparation method of a rice husk carbon-SBS composite modified asphalt mixture, comprising the following steps: step (1), heating the base asphalt in an oven to a completely molten state; step (2), grinding and rolling the rice husk carbon to obtain rice husk carbon powder, and adding the rice husk carbon powder to the base asphalt and stirring; step (3), transferring the mixture of rice husk carbon and base asphalt to a shear machine for high-speed shearing to uniformly disperse the rice husk carbon in the base asphalt; step (4), adding SBS modifier to the mixture of rice husk carbon and base asphalt and continuing to shear in the shear machine to make the SBS modifier compatible with the mixture of rice husk carbon and base asphalt; step (5), adding sulfur to the above-mentioned mixture and performing cooling treatment on the mixture; step (6), stirring the above-mentioned mixture to remove the air bubbles therein to prepare the rice husk carbon-SBS composite modified asphalt; step (7), dry mixing the aggregate and adding the prepared rice husk carbon-SBS composite modified asphalt and stirring; step (8), adding mineral powder and stirring.

[0006] As a preferred technical scheme of the present application: the temperature of the oven in step (1) is set to 150 DEG C.

[0007] As a preferred technical solution of the present invention: the rice husk charcoal powder in step (2) is no larger than 200 mesh.

[0008] As a preferred technical solution of the present invention: the shearing condition in step (3) is to shear at 6000r / min for 30 minutes at 180°C.

[0009] As a preferred technical solution of the present invention: the shearing condition in step (4) is to continue high-speed shearing at 180°C for 40-60 minutes.

[0010] As a preferred technical solution of the present invention: in step (5), after adding sulfur, continue shearing for 10 minutes.

[0011] As another embodiment of the present invention, a rice husk charcoal-SBS composite modified asphalt mixture is provided, which is obtained by the above-described method for preparing rice husk charcoal-SBS composite modified asphalt mixture.

[0012] By adopting the above technical solution, the beneficial effects of the present invention are:

[0013] 1. This invention uses rice husk charcoal and SBS modifier to modify asphalt, which can improve the storage stability of asphalt and the quality of asphalt pavement, thereby improving the service durability of the pavement, reducing the number of maintenance cycles, effectively reducing cost input, and achieving significant economic benefits.

[0014] 2. The rice husk charcoal used in this invention has the advantages of wide availability of raw materials, low price and easy preparation. Its main component is carbon. While significantly improving the rutting resistance, it can also fix a large amount of carbon elements in the engineering structure, reduce the amount of engineering materials used, thereby effectively reducing carbon emissions in the atmosphere. Furthermore, through scientific and reasonable application, it improves the relevant effective performance of the engineering materials used, and has good social and environmental benefits. Attached Figure Description

[0015] Figure 1 This is a flowchart of a method for preparing a rice husk charcoal-SBS composite modified asphalt mixture according to the present invention. Detailed Implementation

[0016] The embodiments of the present invention are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention. In the description of the present invention, it should be understood that the terms "upper," "lower," "front," "upper surface," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as limiting the present invention. In the present invention, unless otherwise expressly specified and limited, the terms "installed," "connected," "joined," "fixed," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or mutual communication; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two elements or the interaction relationship between two elements. For those skilled in the art, the specific meaning of the above terms in the present invention can be understood according to the specific circumstances.

[0017] Styrene-butadiene-styrene (SBS modifier) ​​thermoplastic elastomers are widely used in modified asphalt due to their excellent elasticity and durability. However, traditional SBS modifiers and asphalt are only physically mixed, resulting in poor compatibility and easy segregation at high temperatures, leading to uneven asphalt performance. Furthermore, SBS-modified asphalt has insufficient resistance to high and low temperatures and poor aging resistance.

[0018] In realizing the concept of this invention, it was discovered that by introducing rice husk charcoal material with uniform structure and controllable particle size, and by rationally designing a composite system of rice husk charcoal and SBS modifier, the use of SBS modifier can be reduced while ensuring the performance of asphalt, improving the greenness and resource utilization of the material, realizing the resource utilization of agricultural waste, and promoting the development of sustainable road material technology.

[0019] According to embodiments of the present invention, a method for preparing rice husk charcoal-SBS composite modified asphalt mixture is provided. Figure 1 A flowchart illustrating the preparation method of rice husk charcoal-SBS composite modified asphalt mixture according to an embodiment of the present invention is shown, as follows: Figure 1 As shown, it includes the following steps:

[0020] Step (1): Place the base asphalt in an oven and heat it to a completely melted state. The temperature of the oven is set to 150°C. Using this temperature can make the base asphalt reach a better melting state, provide sufficient fluidity, and avoid excessive thinning of the base asphalt due to excessive temperature.

[0021] Step (2): Grind and crush the rice husk charcoal to obtain rice husk charcoal powder. Add the rice husk charcoal powder to the matrix asphalt and stir for 30 minutes. The rice husk charcoal powder after grinding and crushing should not be larger than 200 mesh to ensure that the rice husk charcoal can be evenly dispersed in the matrix asphalt and to avoid the agglomeration of excessively fine particles due to their large area, which would affect the homogeneity of the mixture.

[0022] Rice husk charcoal improves the high-temperature stability of the base asphalt, enhancing its resistance to rutting and aging. 200-mesh particles provide sufficient interfacial bonding without sacrificing the asphalt's flexibility due to excessive fineness. However, rice husk charcoal is rich in silica; excessively small particle sizes significantly increase its surface activity, leading to uncontrollable reactions with lightweight components in the base asphalt and affecting its long-term durability.

[0023] In step (3), the mixture of rice husk charcoal and matrix asphalt is transferred to a shear mill for high-speed shearing to ensure that the rice husk charcoal is evenly dispersed in the matrix asphalt. During shearing, the mixture is sheared at 180°C and a shearing rate of 6000 r / min for 30 minutes to further improve the dispersion effect of the rice husk charcoal.

[0024] Step (4): Add SBS modifier to the mixture of rice husk charcoal and base asphalt, and continue high-speed shearing in a shearing machine to make the SBS modifier compatible with the mixture of rice husk charcoal and base asphalt. Continue high-speed shearing at 180°C for 40-60 minutes to ensure that the SBS modifier is fully compatible with the base asphalt and rice husk charcoal.

[0025] When SBS modifier, base asphalt, and rice husk charcoal are fully compatible, their interactions mainly manifest as physical blending and limited chemical reactions, jointly affecting the performance of asphalt mixtures. First, the SBS modifier swells and partially dissolves in the asphalt at high temperatures, forming a three-dimensional elastic network structure. The polystyrene (PS) end groups of SBS enhance the elasticity of the asphalt through physical cross-linking, significantly improving its high-temperature rutting resistance and low-temperature crack resistance. The addition of rice husk charcoal introduces amorphous silica and a small amount of metal oxides, mainly affecting the system through physical filling and surface adsorption. Rice husk charcoal particles (≤200 mesh) fill the voids in the asphalt, increasing density and stiffness, while the silanol groups (Si-OH) on the silica surface may form hydrogen bonds or weak chemical bonds with polar components in the asphalt (such as asphaltenes), enhancing interfacial bonding.

[0026] Step (5): Sulfur is added to the above mixture, shearing is continued for 10 minutes, and then the mixture is cooled. At high temperatures, sulfur reacts with the unsaturated double bonds in SBS through a sulfurization cross-linking reaction, forming a more stable three-dimensional network structure. This process significantly enhances the elastic recovery and high-temperature performance of SBS-modified asphalt, while also improving its anti-aging and durability. Rice husk charcoal further influences the above sulfurization process. The amorphous silica and metal oxides in rice husk charcoal may act as inert fillers, physically adsorbing sulfur or polar components in the matrix asphalt, thereby slowing down the rate of the sulfurization reaction.

[0027] Adding sulfur can transform the above-mentioned physical blending into a partially chemically cross-linked composite structure, significantly improving the high-temperature performance and fatigue resistance of the material.

[0028] Step (6): Stir the above mixture to remove air bubbles, thus preparing rice husk charcoal-SBS composite modified asphalt. Removing air bubbles helps eliminate voids and defects within the material, further improving the density and uniformity of the asphalt mixture. The presence of air bubbles reduces the mechanical strength of the material and becomes a stress concentration point under high temperature or load, leading to the initiation and propagation of cracks. By removing these air bubbles, the rutting resistance, fatigue resistance, and durability of the modified asphalt can be significantly improved.

[0029] Step (7): Dry mix the aggregate, add the prepared rice husk charcoal-SBS composite modified asphalt and stir. When dry mixing the aggregate, the aggregate can be preheated, which can fully preheat the aggregate and evaporate its surface moisture, creating ideal conditions for subsequent asphalt coating.

[0030] Step (8): Add mineral powder and stir. As a fine filler, mineral powder can accurately fill the gaps in the aggregate skeleton, reducing the gap ratio of coarse aggregate by 15-20% and significantly improving the density of the mixture. The CaCO3 component in the mineral powder can react with the acidic substances in asphalt to form a stable structured asphalt mastic, which increases the dynamic viscosity of the mixture, ensuring both workability and resistance to deformation.

[0031] In summary, the preparation method of rice husk charcoal-SBS composite modified asphalt mixture of the present invention not only improves the performance of asphalt pavement, but also increases production efficiency, and has significant economic and social benefits.

[0032] The embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to the described embodiments. For those skilled in the art, various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention, and these variations still fall within the protection scope of the present invention.

Claims

1. A method for preparing rice husk charcoal-SBS composite modified asphalt mixture, characterized in that: Includes the following steps: Step (1): Place the base asphalt in an oven and heat it until it is completely melted; Step (2): Grind and crush the rice husk charcoal to obtain rice husk charcoal powder, add the rice husk charcoal powder to the matrix asphalt and stir. Step (3) involves transferring the mixture of rice husk charcoal and matrix asphalt to a shearing machine for high-speed shearing, so that the rice husk charcoal is evenly dispersed in the matrix asphalt. Step (4): Add SBS modifier to the mixture of rice husk charcoal and base asphalt, and continue high-speed shearing in a shearing machine to make the SBS modifier compatible with the mixture of rice husk charcoal and base asphalt. Step (5): Sulfur is added to the above mixture, and the mixture is cooled. Step (6): Stir the above mixture to remove air bubbles and prepare rice husk charcoal-SBS composite modified asphalt; Step (7): Dry mix the aggregate, add the prepared rice husk charcoal-SBS composite modified asphalt and stir. Step (8): Add mineral powder and stir.

2. The method for preparing a rice husk charcoal-SBS composite modified asphalt mixture according to claim 1, characterized in that: The oven temperature in step (1) is set to 150°C.

3. The method for preparing a rice husk charcoal-SBS composite modified asphalt mixture according to claim 1, characterized in that: The rice husk charcoal powder in step (2) is no larger than 200 mesh.

4. The method for preparing a rice husk charcoal-SBS composite modified asphalt mixture according to claim 1, characterized in that: The shearing conditions in step (3) are: shearing at 180°C and a shearing rate of 6000 r / min for 30 minutes.

5. The method for preparing a rice husk charcoal-SBS composite modified asphalt mixture according to claim 4, characterized in that: The shearing conditions in step (4) are to continue high-speed shearing at 180°C for 40-60 minutes.

6. The method for preparing a rice husk charcoal-SBS composite modified asphalt mixture according to claim 5, characterized in that: In step (5), after adding sulfur, continue shearing for 10 minutes.

7. A rice husk charcoal-SBS composite modified asphalt mixture, which is obtained by the preparation method described in any one of claims 1-6.

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