Preparation method of composite modified asphalt

Abstract

The application provides a preparation method of a composite modified asphalt, and particularly relates to the technical field of preparation of an asphalt anti-aging agent.The preparation method comprises the following steps: mixing a lignin raw material with an acidic lithium bromide solution, and performing a reaction under a heating condition; after the reaction is completed, centrifugation, washing, suction filtration, vacuum drying and grinding are performed to obtain degraded lignin; and the degraded lignin, quercetin, a stabilizer and sodium xanthate are added into asphalt as the anti-aging agent to obtain modified asphalt with high anti-aging performance.The application realizes value-added utilization of lignin, reduces environmental pollution caused by the lignin raw material, improves the service performance of the asphalt, and helps to alleviate the consumption of non-renewable resources such as asphalt.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of preparation of asphalt anti-aging agents, in particular to a preparation method of a composite modified asphalt. BACKGROUND

[0002] Asphalt pavement is widely used due to its excellent performance. Compared with cement pavement, asphalt pavement has many advantages, such as driving comfort, low noise, convenient maintenance, etc. In the construction of high-grade pavement in China, the proportion of asphalt pavement is as high as 90%. The design service life of asphalt pavement on expressway is 15 to 20 years, but the actual service life is far from this number. Asphalt is mostly a byproduct of petroleum, and the increasing demand for asphalt will further lead to the consumption of petroleum resources. Therefore, improving the service life of asphalt pavement is an important direction of current road research.

[0003] The service life of asphalt pavement is closely related to the aging of asphalt. Under the influence of complex environmental factors (temperature, ultraviolet light, oxygen, humidity), asphalt will age, and in this process, its molecular weight increases, the chemical components reorganize, resulting in changes in the physical and chemical properties of asphalt. This change increases the viscosity and brittleness of asphalt, which is prone to low-temperature and fatigue cracking under the action of vehicle load, and seriously reduces the service life of the pavement. Therefore, improving the anti-aging performance of asphalt is an urgent issue. The commonly used method is to add modifiers to improve the anti-aging performance of asphalt, including carbon black, industrial salt, nanomaterials, layered double hydroxide (LDH), and polymers. However, these materials have certain limitations in practical application, including 1) affecting the rheological properties of asphalt materials; 2) high cost; 3) producing environmentally harmful reagents.

[0004] In contrast, lignin is a highly potential environmentally friendly anti-aging modifier due to its low cost, non-toxicity, renewability, and similarity to the molecular structure of asphalt. However, due to its heterogeneity and low reactivity, its anti-aging activity is limited, resulting in less application in asphalt anti-aging agents. In addition, lignin is often used as a low-value fuel for heat and electricity as industrial waste, and only less than 2% of lignin is used for value-added products other than fuel. This has a great impact on the environment. Therefore, in order to release the potential of lignin, there is an urgent need for a process that can physically and chemically modify lignin and improve its reactivity.

[0005] In summary, in order to save petroleum resources and scientifically solve the environmental pollution problem of waste lignin, it is of great social and environmental value to use waste lignin for asphalt modification. At present, the research on lignin modified asphalt in China mainly focuses on the physical modification level of experimental conditions (temperature, dosage, stirring intensity), and the research on the chemical modification of lignin on asphalt is still insufficient.

[0006] The present application is distinguished from the prior art as follows:

[0007] Compared with the technology of patent CN114539789A "Asphalt Anti-aging Agent and Its Preparation Method and Use Method"

[0008] Patent CN114539789A prepares an asphalt anti-aging agent by uniformly mixing untreated raw lignin material with quercetin, sodium xanthate, aromatic oil and stabilizer; while the present patent first uses an acidic lithium bromide solution to dissolve and treat raw lignin, and then obtains degraded lignin with increased phenolic hydroxyl content through heating reaction, centrifugation, washing, suction filtration, vacuum drying and grinding processes, and then uses the degraded lignin, quercetin, sodium xanthate and stabilizer to prepare composite modified asphalt. The two have fundamental differences in the treatment method of lignin as raw material.

[0009] Patent CN114539789A obtains an asphalt anti-aging agent by uniformly mixing lignin with quercetin, sodium xanthate, aromatic oil and stabilizer in advance and performing shear treatment, and then mixes the anti-aging agent with asphalt in a specific ratio to prepare modified asphalt; the present patent uses a separate addition process, i.e. adding degraded lignin, quercetin, stabilizer and sodium xanthate in a certain proportion in turn in heated asphalt to prepare composite modified asphalt. The two have substantial differences in the preparation method of modified asphalt.

[0010] The raw materials used by patent CN114539789A to prepare asphalt anti-aging agent include lignin, quercetin, sodium xanthate, aromatic oil and stabilizer; while the raw materials used by the present patent to prepare composite modified asphalt are degraded lignin, quercetin, stabilizer and sodium xanthate, and do not include aromatic oil. The two have significant differences in the preparation of raw materials for modified asphalt.

[0011] Therefore, in order to solve the above problems, the present application uses chemical modification of waste lignin, and then applies it to prepare composite modified asphalt to improve the anti-aging performance and fatigue resistance of asphalt and prolong the service life of asphalt pavement. SUMMARY

[0012] To solve the above technical problems, the present application proposes a preparation method of composite modified asphalt, which aims to chemically depolymerize lignin under simple and mild reaction conditions, effectively degrade lignin while preventing lignin from polymerizing itself, and improve the reaction active sites of lignin. The composite modified asphalt prepared from the degraded lignin has excellent anti-aging performance and fatigue resistance, and can partially replace petroleum asphalt.

[0013] To achieve the above purpose, the technical scheme adopted by the present application is:

[0014] A preparation method of composite modified asphalt, comprising the following steps:

[0015] (1) Lignin modification: the sieved lignin is dissolved in an acidic lithium bromide solution, heated and reacted in an oil bath, after the reaction is completed, the reaction solution is cooled, centrifuged, washed, suction filtered, vacuum dried and ground to obtain degraded lignin;

[0016] (2) The degraded lignin obtained in step (1) is mixed with asphalt in a container, the reaction container is placed in a heat preservation sleeve for high-speed shearing treatment, quercetin, a stabilizer and sodium xanthate are sequentially added during the shearing process, and after the shearing is completed, a composite modified asphalt is obtained.

[0017] As a further improvement of the present application, the mass concentration of the acidic lithium bromide solution in step (1) is 10-60%.

[0018] As a further improvement of the present application, the reaction conditions of the lignin and the acidic lithium bromide in step (1) are 90-130℃ in the oil bath for 0.5-5h.

[0019] As a further improvement of the present application, the particle size of the lignin is 40-60 mesh.

[0020] As a further improvement of the present application, the lignin includes hydrolyzed lignin, alkali lignin or organic lignin.

[0021] As a further improvement of the present application, the acidic lithium bromide solution is prepared by adding HCl solution in lithium bromide aqueous solution, the lithium bromide solution has a concentration of 10-60wt%, and the solution has an acid concentration of 0.5-2.4 mol / L, preferably 2.4 mol / L.

[0022] As a further improvement of the present application, the mass-to-volume ratio of the lignin and the acidic lithium bromide solution is 1:10-15, preferably 1:10, g / mL.

[0023] As a further improvement of the present application, during the centrifugation, washing, suction filtration and vacuum drying processes, the filter cake obtained after suction filtration is vacuum dried at 40-60℃.

[0024] As a further improvement of the present application, the mass ratio of quercetin: stabilizer: sodium xanthate is 3-9:100:1-3:3-5:3-5.

[0025] As a further improvement of the present application, the preparation of the modified asphalt in step (2) is as follows:

[0026] The degraded lignin is mixed with the asphalt and placed in a 150℃ heat preservation cover, the rotor of a shearing instrument is placed in the mixture, the shearing switch is turned on, the rotating speed of the rotor is increased to 1000r / min and kept unchanged, shearing is performed for 5min, and then the shearing is stopped; quercetin is added, the shearing switch is turned on, the rotating speed of the rotor is increased to 1000r / min and kept unchanged, shearing is performed for 5min, and then the shearing is stopped; the stabilizer is added, the shearing switch is turned on, the rotating speed of the rotor is increased to 1000r / min and kept unchanged, shearing is performed for 5min, and then the shearing is stopped; sodium xanthate is added, the shearing switch is turned on, the rotating speed of the rotor is increased to 1000r / min and kept unchanged, shearing is performed for 5min, then the rotating speed of the rotor is increased to 5000r / min, shearing is performed for 40min, and then the shearing is stopped. After shearing is completed, the mixed asphalt is cooled to room temperature at room temperature, and the composite modified asphalt can be obtained.

[0027] Compared with the prior art, the present application has the following beneficial effects:

[0028] The composite modified asphalt prepared by the present application has greatly improved anti-aging performance and anti-fatigue performance. After short-term aging, the carbonyl index of the composite modified asphalt is reduced by 30.5%~47.4% compared with 70# base asphalt, and by 37.9%~45.1% compared with unmodified lignin asphalt; the sulfoxide index is reduced by 18.2%~31.4% compared with 70# base asphalt, and by 18.4%~29.1% compared with unmodified lignin asphalt; after ultraviolet aging for 50 hours, the carbonyl index is reduced by 15.7%~27.4% compared with 70# base asphalt, and by 13.1%~25.2% compared with unmodified lignin asphalt; the sulfoxide index is reduced by 21.2%~35.7% compared with 70# base asphalt, and by 18.2%~33.2% compared with unmodified lignin asphalt. After ultraviolet aging for 50 hours, the fatigue life of the composite modified asphalt at a stress level of 2.5% is 6401~7109 times, and the fatigue life at a stress level of 5% is 429~491 times. Therefore, the composite modified asphalt can replace asphalt, not only realizing value-added application of lignin, but also improving the performance of the pavement and reducing the consumption of petroleum resources. DETAILED DESCRIPTION

[0029] The present application will be further described in detail below with the specific embodiments:

[0030] 5g of lignin is dissolved in a pressure bottle containing 50mL of acidic lithium bromide solution (lithium bromide concentration is 60wt%, hydrochloric acid concentration is 2.4 mol / L), the pressure bottle is sealed and placed in a 110℃ magnetic stirrer, the magnetic stirrer is started, and after 2 hours of reaction, the pressure bottle is placed in ice water for cooling to stop the reaction. The cooled reaction liquid is centrifuged, washed, filtered, and dried in a 40℃ vacuum drying oven until the weight is constant. After drying, the degraded lignin is ground.

[0031] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C heat preservation sleeve, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 3 g of quercetin is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of a stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of sodium xanthate is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, then the rotation speed of the rotor is increased to 5000 r / min, shearing for 40 min, and the shearing is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and a composite modified pitch is obtained. Example

[0032] 5 g of lignin is dissolved in a pressure bottle containing 50 mL of an acidic lithium bromide solution (lithium bromide concentration is 60 wt%, hydrochloric acid concentration is 2.4 mol / L), the pressure bottle is sealed and placed in a 120 °C magnetic stirrer, the magnetic stirrer is turned on, and after 2 hours of reaction, the pressure bottle is placed in ice water for cooling to stop the reaction. The cooled reaction liquid is centrifuged, washed, suction filtered, and dried in a 40 °C vacuum drying oven to constant weight, and the dried degraded lignin is ground.

[0033] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C heat preservation sleeve, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 3 g of quercetin is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of a stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of sodium xanthate is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, then the rotation speed of the rotor is increased to 5000 r / min, shearing for 40 min, and the shearing is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and a composite modified pitch is obtained. Example

[0034] 5g of lignin was dissolved in a pressure flask containing 50mL of acidic lithium bromide solution (60wt% lithium bromide, 2.4mol / L hydrochloric acid). The pressure flask was sealed and placed in a magnetic stirrer at 110℃. After stirring for 3 hours, the pressure flask was placed in ice water to cool and stop the reaction. The cooled reaction solution was centrifuged, washed, filtered, and dried in a vacuum drying oven at 40℃ to constant weight. After drying, it was ground to obtain degraded lignin.

[0035] (2) Place 100g of 70# base asphalt in a 150℃ oven for 40 min. Take 6g of the degraded lignin obtained in step (1) and mix it with the asphalt, then place it in a 150℃ heat-insulating jacket. Place the rotor of the shearing apparatus in the mixture, turn on the shearing switch, increase the rotor speed to 1000r / min and keep it constant, shear for 5 min, then stop shearing. Add 1g of quercetin, turn on the shearing switch, increase the rotor speed to 1000r / min and keep it constant, shear for 5 min, then stop shearing. Add 3g of stabilizer, turn on the shearing switch, increase the rotor speed to 1000r / min and keep it constant, shear for 5 min, then stop shearing. Add 3g of sodium xanthate, turn on the shearing switch, increase the rotor speed to 1000r / min and keep it constant, shear for 5 min, then increase the rotor speed to 5000r / min and shear for 40 min, then stop shearing. After shearing, cool the mixed asphalt to room temperature to obtain the composite modified asphalt. Example

[0036] 5g of lignin was dissolved in a pressure bottle containing 50mL of acidic lithium bromide solution (60wt% lithium bromide, 2.0 mol / L hydrochloric acid). The pressure bottle was sealed and placed in a magnetic stirrer at 110℃. After stirring for 2 hours, the pressure bottle was placed in ice water to cool and stop the reaction. The cooled reaction solution was centrifuged, washed, filtered, and dried in a vacuum drying oven at 40℃ to constant weight. After drying, it was ground to obtain degraded lignin.

[0037] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C heat preservation sleeve, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 3 g of quercetin is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of a stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of sodium xanthate is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, then the rotation speed of the rotor is increased to 5000 r / min, shearing for 40 min, and the shearing is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and a composite modified pitch is obtained. Example

[0038] 5 g of lignin is dissolved in a pressure bottle containing 50 mL of an acidic lithium bromide solution (lithium bromide concentration is 60 wt%, hydrochloric acid concentration is 2.4 mol / L), the pressure bottle is sealed and placed in a 110 °C magnetic stirrer, the magnetic stirrer is turned on, and after 3 hours of reaction, the pressure bottle is placed in ice water for cooling to stop the reaction. The cooled reaction liquid is centrifuged, washed, suction filtered, and dried in a 40 °C vacuum drying oven to constant weight, and the dried lignin is ground to obtain degraded lignin.

[0039] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C heat preservation sleeve, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 3 g of quercetin is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of a stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of sodium xanthate is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, then the rotation speed of the rotor is increased to 5000 r / min, shearing for 40 min, and the shearing is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and a composite modified pitch is obtained.

[0040] Put 100 g of 70# base pitch in a 150 °C oven for 40 min, take 6 g of lignin and mix with the pitch and place in a 150 °C heat jacket, place the rotor of the shear instrument in the mixture, turn on the shear switch, increase the rotor speed to 1000 r / min and keep it constant, shear for 20 min, then increase the rotor speed to 5000 r / min, shear for 40 min, stop shearing. After shearing is complete, cool the mixed pitch to room temperature at room temperature, and lignin modified pitch is obtained.

[0041] Put 100 g of 70# base pitch in a 150 °C oven for 40 min, take 6 g of lignin and mix with the pitch and place in a 150 °C heat jacket, place the rotor of the shear instrument in the mixture, turn on the shear switch, increase the rotor speed to 1000 r / min and keep it constant, shear for 20 min, then increase the rotor speed to 5000 r / min, shear for 40 min, stop shearing. After shearing is complete, cool the mixed pitch to room temperature at room temperature, and lignin modified pitch is obtained.

[0042] Dissolve 5 g of lignin in a pressure bottle containing 50 mL of acidic lithium bromide solution (lithium bromide concentration of 60 wt%, hydrochloric acid concentration of 2.4 mol / L), seal the pressure bottle and place it in a 110 °C magnetic stirrer, turn on the magnetic stirrer, react for 3 hours, then place the pressure bottle in ice water to cool and stop the reaction. Centrifuge, wash, suction filter, and dry in a 40 °C vacuum drying oven to constant weight, then grind to obtain degraded lignin.

[0043] (2) Put 100 g of 70# base pitch in a 150 °C oven for 40 min, take 6 g of degraded lignin obtained in step (1) and mix with the pitch and place in a 150 °C heat jacket, place the rotor of the shear instrument in the mixture, turn on the shear switch, increase the rotor speed to 1000 r / min and keep it constant, shear for 20 min, then increase the rotor speed to 5000 r / min, shear for 40 min, stop shearing. After shearing is complete, cool the mixed pitch to room temperature at room temperature, and lignin modified pitch is obtained.

[0044] Dissolve 5 g of lignin in a pressure bottle containing 50 mL of acidic lithium bromide solution (lithium bromide concentration of 60 wt%, hydrochloric acid concentration of 2.4 mol / L), seal the pressure bottle and place it in a 110 °C magnetic stirrer, turn on the magnetic stirrer, react for 3 hours, then place the pressure bottle in ice water to cool and stop the reaction. Centrifuge, wash, suction filter, and dry in a 40 °C vacuum drying oven to constant weight, then grind to obtain degraded lignin.

[0045] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C heat preservation sleeve, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and then the shear is stopped; 5 g of the stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and then the shear is stopped; 5 g of sodium xanthate is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and then the rotation speed of the rotor is increased to 5000 r / min, shearing for 45 min, and then the shear is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and the composite modified pitch is obtained.

[0046] 5 g of lignin is dissolved in a pressure bottle containing 50 mL of an acidic lithium bromide solution (lithium bromide concentration is 60 wt%, hydrochloric acid concentration is 2.4 mol / L), the pressure bottle is sealed and placed in a 110 °C magnetic stirrer, the magnetic stirrer is started, and after 3 hours of reaction, the pressure bottle is placed in ice water for cooling to stop the reaction. The cooled reaction solution is centrifuged, washed, suction filtered, and dried in a 40 °C vacuum drying oven to constant weight. After drying, the degraded lignin is obtained by grinding.

[0047] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C heat preservation sleeve, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and then the shear is stopped; 5 g of the stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and then the shear is stopped; 5 g of sodium xanthate is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and then the rotation speed of the rotor is increased to 5000 r / min, shearing for 45 min, and then the shear is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and the composite modified pitch is obtained.

[0048] 5 g of lignin is dissolved in a pressure bottle containing 50 mL of an acidic lithium bromide solution (lithium bromide concentration is 60 wt%, hydrochloric acid concentration is 2.4 mol / L), the pressure bottle is sealed and placed in a 110 °C magnetic stirrer, the magnetic stirrer is started, and after 3 hours of reaction, the pressure bottle is placed in ice water for cooling to stop the reaction. The cooled reaction solution is centrifuged, washed, suction filtered, and dried in a 40 °C vacuum drying oven to constant weight. After drying, the degraded lignin is obtained by grinding.

[0049] (2) 100 g of 70# base pitch is placed in a 150 °C oven for 40 min, 6 g of the degraded lignin obtained in step (1) is mixed with the pitch and placed in a 150 °C holding jacket, the rotor of the shear instrument is placed in the mixture, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of quercetin is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, and the shearing is stopped; 5 g of a stabilizer is added, the shear switch is turned on, the rotation speed of the rotor is increased to 1000 r / min and kept unchanged, shearing for 5 min, then the rotation speed of the rotor is increased to 5000 r / min, shearing for 45 min, and the shearing is stopped. After the shearing is completed, the mixed pitch is cooled to room temperature at room temperature, and the composite modified pitch is obtained.

[0050] The phenolic hydroxyl content of examples 1-6 and comparative examples 1-6 and the carbonyl index and sulfoxide index of the modified pitch under different aging states are shown in Table 1.

[0051] Table 1

[0052]

[0053] From Table 1, it can be observed that the phenolic hydroxyl content of the degraded lignin is significantly improved by about 21.2%~35.4% compared with the unmodified lignin, indicating that the lignin phenolic hydroxyl content can be effectively improved by using the method of the present application. Comparing examples 1-5 and comparative examples 1-2, the carbonyl index and sulfoxide index of the composite modified pitch under two aging states are less than that of 70# base pitch, and the carbonyl index and sulfoxide index of example 3 are the smallest. After short-term aging, the carbonyl index of example 3 is reduced by 47.4% compared with 70# base pitch, and the sulfoxide index is reduced by 31.4%. After 50 hours of ultraviolet aging, the carbonyl index of example 3 is reduced by 27.4% compared with 70# base pitch, and the sulfoxide index is reduced by 35.6%. The above data shows that the anti-aging performance of the composite modified pitch is better than that of 70# base pitch. Comparing examples 1-5 and comparative examples 3-6, it can be seen that the modified pitch added with degraded lignin, quercetin, stabilizer and sodium xanthate has the lowest carbonyl index and sulfoxide index, and the addition of any one of the aging agents reduces the two indexes, especially comparative example 3, which does not add quercetin, stabilizer and sodium xanthate, shows the highest carbonyl index and sulfoxide index, i.e. poor anti-aging performance. It shows that the addition of anti-aging in the composite modified pitch of the present application is crucial. The composite modified pitch prepared by the present application simultaneously uses degraded lignin, quercetin, stabilizer and sodium xanthate, has excellent anti-thermal-oxidative aging effect, and also has good anti-ultraviolet aging effect.

[0054] The fatigue life of examples 1-6 and comparative examples 1-6 after ultraviolet aging for 50 hours is shown in table 2.

[0055] Table 2

[0056]

[0057] As shown in table 2, compared with 70# base asphalt, the fatigue resistance of modified asphalt at two stress levels is improved, and compared with modified asphalt prepared by unmodified lignin, the fatigue life of composite modified asphalt with degraded lignin is increased, especially in example 3, which is increased by 28.6% at 2.5% stress level and 35.6% at 5% stress level, indicating that the degraded lignin can further improve the fatigue resistance of asphalt, thereby improving the service life of asphalt. Similarly, the fatigue life of composite asphalt in examples 1-5 is higher than that of composite asphalt in comparative examples 3-6 without any anti-aging agent, which is 6401-7109 times at 2.5% stress level and 429-491 times at 5% stress level, indicating that the anti-aging agent in the present application is necessary and can significantly improve the fatigue resistance.

[0058] The present application provides a preparation method of composite modified asphalt, which realizes the value-added utilization of lignin, and the manufactured composite modified asphalt can replace ordinary asphalt and has excellent anti-aging and fatigue resistance. In addition, the content of asphalt in the composite modified lignin is lower than that of ordinary asphalt, and the amount of volatile organic matter is relatively reduced, which not only protects the environment, but also greatly reduces the harm to human health.

[0059] The above description is only a preferred embodiment of the present application, and is not intended to limit the present application in any other form, and any modification or equivalent change made according to the technical essence of the present application still falls within the scope of the present application.

Claims

1. A method for preparing composite modified asphalt, characterized in that: Includes the following steps: (1) Lignin modification: The sieved lignin is dissolved in an acidic lithium bromide solution and heated in an oil bath. After the reaction is completed, the reaction solution is cooled, centrifuged, washed, filtered, vacuum dried and ground to obtain degraded lignin. (2) The degraded lignin obtained in step (1) is mixed with asphalt in a container. The reaction container is placed in a heat-insulating jacket for high-speed shearing. During the shearing process, quercetin, stabilizer and sodium xanthate are added in sequence. After the shearing is completed, composite modified asphalt is obtained. The preparation of modified asphalt in step (2) is as follows: Degraded lignin was mixed with asphalt and placed in a 150℃ insulated jacket. The rotor of the shearing apparatus was placed in the mixture, the shearing switch was turned on, and the rotor speed was increased to 1000 r / min and kept constant for 5 minutes, then shearing was stopped. Quercetin was added, the shearing switch was turned on, and the rotor speed was increased to 1000 r / min and kept constant for 5 minutes, then shearing was stopped. Stabilizer was added, the shearing switch was turned on, and the rotor speed was increased to 1000 r / min and kept constant for 5 minutes, then shearing was stopped. Sodium xanthate was added, the shearing switch was turned on, and the rotor speed was increased to 1000 r / min and kept constant for 5 minutes, then the rotor speed was increased to 5000 r / min and sheared for 40 minutes, then shearing was stopped. After shearing, the mixed asphalt was cooled to room temperature to obtain the composite modified asphalt.

2. The method for preparing composite modified asphalt according to claim 1, characterized in that: In step (1), the mass concentration of the acidic lithium bromide solution is 10-60%.

3. The method for preparing composite modified asphalt according to claim 1, characterized in that: The reaction conditions for lignin and acidic lithium bromide in step (1) are as follows: the reaction is carried out in an oil bath at 90~130℃ for 0.5~5h.

4. The method for preparing composite modified asphalt according to claim 1, characterized in that: The lignin has a particle size of 40-60 mesh.

5. The method for preparing composite modified asphalt according to claim 1, characterized in that, The lignin mentioned includes hydrolyzed lignin, alkali lignin, or organic lignin.

6. The method for preparing composite modified asphalt according to claim 1, characterized in that, The acidic lithium bromide solution is prepared by adding HCl solution to an aqueous lithium bromide solution. The concentration of the lithium bromide solution is 10-60 wt%, and the concentration of the acid solution is 0.5-2.4 mol / L.

7. The method for preparing composite modified asphalt according to claim 1, characterized in that, The mass-to-volume ratio of lignin to acidic lithium bromide solution is 1:10~15.

8. The method for preparing composite modified asphalt according to claim 1, characterized in that, During the centrifugation, washing, filtration and vacuum drying process, the filter cake is washed with deionized water 3 to 4 times and then vacuum dried at 40 to 60°C.

9. The method for preparing composite modified asphalt according to claim 1, characterized in that, The mass ratio of lignin: pitch: quercetin: stabilizer: sodium xanthate is 3~9:100:1~3:3~5:3~5.

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