Preparation method of graphene modified asphalt concentrated solution

Abstract

The invention discloses a preparation method of a graphene modified asphalt concentrated solution, and belongs to the technical field of road materials. According to the method, the graphene modified asphalt concentrated solution with high dispersity and high stability is prepared through the optimized component formula and the process steps of stripping firstly and stabilizing secondly. The concentrated solution is prepared from graphene, a dispersing agent, a stabilizing agent and carrier oil, and the mass ratio of the graphene is 1%-15%. The preparation method comprises the following steps: performing mechanical stirring and ultrasonic treatment on the graphene in the carrier oil to realize pre-dispersion and stripping; then adding a stabilizer, and performing high-speed shearing to refine and stabilize; and finally, carrying out homogenization treatment to obtain a finished product. The concentrated solution has excellent storage stability, can be quickly and uniformly dispersed in asphalt, is convenient to use and is suitable for different engineering scenes. When the modified asphalt is used for modifying matrix asphalt, the high-temperature stability, low-temperature crack resistance and aging resistance of the asphalt can be remarkably improved, and the modified asphalt is suitable for long-service-life pavement engineering such as high-grade highways and airport runways.

Description

TECHNICAL FIELD

[0001] TECHNICAL FIELD BACKGROUND

[0002] As the core material of road construction, the performance of asphalt directly affects the service life and driving safety of the pavement. With the increasing traffic load and the frequent occurrence of extreme weather, traditional base asphalt has been difficult to meet the demand of high-performance pavement. Graphene, as a new type of nanomaterial, has excellent mechanical properties, thermal conductivity and interface enhancement effect, and is widely used in the field of asphalt modification, which can significantly improve the high-temperature stability, low-temperature crack resistance and aging resistance of asphalt. As a nanomaterial, graphene has great potential in asphalt modification, which can significantly improve the high-temperature stability, aging resistance and fatigue resistance of asphalt. However, there are great challenges in directly adding nanoscale graphene into high-viscosity asphalt: first, graphene has a large specific surface area and high surface energy, which is prone to agglomeration and difficult to achieve nanoscale dispersion through conventional mechanical stirring; second, the interface compatibility between graphene and asphalt is poor, which is prone to phase separation during storage and use, resulting in degradation or even failure of the modification effect. At present, the methods to improve the dispersion of graphene in asphalt mainly include high-speed shearing method and chemical modification method. The high-speed shearing method consumes high energy, and the graphene is prone to re-agglomeration after the shearing action stops, which cannot achieve long-term stable dispersion. The chemical modification method (such as acid oxidation and silane coupling agent treatment) can improve the compatibility, but the process is complex, which may damage the intrinsic structure of graphene, and the introduced chemical groups may not be stable at high temperature, affecting the performance of the final product. The main technical problems existing at present are: 1. Poor dispersibility: graphene has high surface energy and is prone to agglomeration in asphalt, which requires a large amount of solvent or complex process to achieve uniform dispersion, increasing the production cost; 2. Inconvenient transportation and storage: the directly prepared graphene modified asphalt is a viscous fluid, which has high transportation cost and is prone to delamination during long-term storage; 3. Low flexibility in on-site construction: traditional modified asphalt needs to be pre-prepared in the factory, which is difficult to adjust the modifier concentration flexibly according to the on-site demand and adapt to different engineering scenarios; 4. Limited compatibility: the interface compatibility between graphene and asphalt is limited, which restricts the enhancement effect when added alone, and relies on a large amount of polymer (such as SBS) for synergistic modification, further increasing the cost. Therefore, the development of a graphene modified asphalt concentrate with high concentration, high dispersibility, storage stability and easy on-site adjustment is of great importance to promote the large-scale application of graphene modified asphalt. The preparation of graphene into a high-concentration and high-stability concentrate is an effective way to solve the dispersion problem, but the existing technology has problems such as poor storage stability and poor compatibility with asphalt. SUMMARY

[0003] The present application aims to overcome the defects of poor dispersibility, inconvenience of transportation and storage, low construction flexibility, etc. of the existing graphene modified asphalt, and provides a preparation method of graphene modified asphalt concentrate. The method prepares a graphene concentrate with excellent storage stability and easy dispersion through an optimized component formula and a unique "first peeling, then stabilizing" process, realizes efficient dispersion of graphene in asphalt, forms a high-concentration stable system, and can be used flexibly according to engineering requirements, taking into account performance improvement and economy. The concentrate can be directly used for asphalt modification and can fully exert the reinforcing effect of graphene.1. Technical scheme: (1) A graphene modified asphalt concentrate, characterized in that it is prepared from graphene, dispersant, stabilizer and carrier oil; wherein the components are as follows in mass percentage: 1) graphene: 1%-15%; 2) dispersant: 0.5%-8%; 3) stabilizer: 0.2%-5%; 4) carrier oil: 72%-98.3%. Wherein: 1) the graphene is graphene oxide or reduced graphene oxide, with a sheet diameter of 0.5-20 μm and a layer number of less than 10. 2) the dispersant is a non-ionic surfactant or a high molecular dispersant, including but not limited to at least one of Span 80, Tween 80, polyvinylpyrrolidone. 3) the stabilizer is a silane coupling agent, including but not limited to at least one of KH-550, KH-560, KH-570. 4) the carrier oil is aromatic hydrocarbon oil with an aromatic content of more than 40%, rubber oil or coal tar. (2) The preparation method of the above graphene modified asphalt concentrate, characterized in that it comprises the following steps: 1) First step: pre-dispersion and peeling of graphene: metered graphene, dispersant and first part of carrier oil are added to a first mixing container, stirred at a speed of 800-1500 rpm and a temperature of 40-60°C for 20-40 minutes to obtain a preliminary dispersed slurry; then the slurry is transferred to an ultrasonic processor, treated under the conditions of power 800-1500 W and ice water bath cooling for 30-90 minutes to obtain a graphene primary dispersion. 2) Second step: high-speed shearing refinement and stabilization: the graphene primary dispersion obtained in step 1 is transferred to a high-speed shearing machine, and the stabilizer and the second part of the carrier oil are added, and high-speed shearing is carried out at a temperature of 60-80°C and a speed of 3000-6000 rpm for 40-80 minutes. 3) Third step: homogenization and finished product: the material treated in step 2 is transferred to a homogenization reactor, the remaining carrier oil is added, and stirring is carried out at a temperature of 70-90°C and a speed of 200-400 rpm for 60-120 minutes to fully homogenize, and then cooled and filtered to obtain the graphene modified asphalt concentrate.(3) The application of the graphene modified asphalt concentrate in asphalt modification, characterized in that: the concentrate is mixed with base asphalt at a temperature of 160-180°C by mechanical stirring for 20-40 minutes at a stirring speed of 400-800 rpm in a required proportion; the addition amount of the concentrate is such that the mass fraction of graphene in the final modified asphalt is 0.05%-1.5%. Advantages

[0004] Compared with the prior art, the present application has the following advantages: 1. Excellent dispersibility: through the physical dispersion process combining "ultrasonic peeling" and "high-speed shearing", the van der Waals force between graphene layers is effectively overcome, achieving nanoscale dissociation and stable dispersion of graphene in the oil phase, and avoiding performance defects caused by agglomeration 2. Excellent storage stability: through the combined action of the steric hindrance effect of the dispersant and the interface coupling effect of the stabilizer, single-layer dispersion of graphene in the concentrate is achieved, and the storage stability is excellent at 60°C for 30 days without stratification, and the agglomeration rate of graphene is ≤5%; the concentrate can be stored for a long time (≥6 months) without obvious sedimentation and agglomeration, solving the worldwide problem of poor storage stability of nano-modifiers. 3. Easy to use and good compatibility: the concentrate has excellent compatibility with asphalt, and does not require complex equipment when used; the concentrate can be diluted as needed, and only low-speed stirring is required to quickly and uniformly disperse in asphalt, greatly simplifying the production process, reducing the application threshold and energy consumption. It is suitable for different engineering requirements for modification strength, reduces transportation cost by more than 30%, and can be used after on-site stirring; 4. Significant modification effect: the concentrate prepared by the present application can be used for various grades of base asphalt, and the high-temperature anti-rutting factor of the modified asphalt obtained after dilution of the concentrate is improved by more than 50% at 60°C, and the low-temperature ductility is improved by more than 80% at -10°C, significantly improving the high-temperature performance and fatigue resistance of asphalt, providing key material support for long-life pavement; 5. Process can be industrialized: the preparation process does not require special equipment and can be realized by modifying the existing modified asphalt production line, suitable for large-scale production. Specific embodiments Sample Softening point / °C 5°C elongation / cm 135°C kinematic viscosity / (Pa·s) Differential softening point / °C Elongation after TFOT (5°C) / cm Example 1 82.5 35.2 2.15 1.2 25.6 Example 2 80.8 32.7 2.25 1.5 23.8 Comparative Example 1 72.3 22.4 2.35 3.8 16.2 All performance indicators are far superior to base asphalt and conventional SBS modified asphalt, proving that the concentrate has excellent modification effect.

Claims

1. A method for preparing graphene-modified asphalt concentrate, characterized in that, The process includes the following steps: (1) Step 1: Mix graphene, dispersant and first part carrier oil, first disperse by mechanical stirring, and then treat by ultrasonication to obtain graphene primary dispersion; (2) Step 2: Add stabilizer and second part carrier oil to the primary dispersion obtained in step (1), and treat by high-speed shearing; (3) Step 3: Add the remaining carrier oil to the material after step 2), stir to homogenize, cool and filter to obtain the graphene modified asphalt concentrate.

2. The method according to claim 1, characterized in that: In step (1), the mechanical stirring conditions are: rotation speed 800-1500 rpm, temperature 40-60°C, time 20-40 minutes; the ultrasonic treatment conditions are: power 800-1500W, under ice water bath conditions, treatment for 30-90 minutes.

3. The method according to claim 1, characterized in that: In step (2), the conditions for high-speed shearing are: rotation speed 3000-6000 rpm, temperature 60-80°C, and time 40-80 minutes.

4. The method according to claim 1, characterized in that: In step (3), the conditions for stirring and homogenizing are: rotation speed 200-400 rpm, temperature 70-90°C, and time 60-120 minutes.

5. The method according to claim 1, characterized in that: The graphene is graphene oxide or reduced graphene oxide, with a sheet diameter of 0.5-20 μm and fewer than 10 layers.

6. The method according to claim 1, characterized in that: The dispersant is at least one of a nonionic surfactant or a polymeric dispersant; the stabilizer is a silane coupling agent; and the carrier oil is an aromatic oil, rubber oil, or coal tar with an aromatic content greater than 40%.

7. A graphene-modified asphalt concentrate prepared by the method according to any one of claims 1-6, characterized in that: By mass percentage, its composition is: 1%-15% graphene, 0.5%-8% dispersant, 0.2%-5% stabilizer, and 72%-98.3% carrier oil.

8. The application of the graphene-modified asphalt concentrate as described in claim 7, characterized in that: The method for using it to modify base asphalt is as follows: the concentrate is mixed with base asphalt at 160-180°C for 20-40 minutes by mechanical stirring; the amount of concentrate added is such that the mass ratio of graphene in the final modified asphalt is 0.05%-1.5%.

9. A high-performance modified asphalt, characterized in that: It is made by mixing and stirring base asphalt and graphene-modified asphalt concentrate as described in claim 7.

10. The application of the high-performance modified asphalt as described in claim 9 in the paving of high-grade highways, airport runways, bridge deck pavements, or long-life road surfaces.