A modified asphalt and a method for preparing and using the same

Abstract

The application belongs to the technical field of asphalt, and particularly relates to a modified asphalt, a preparation method and application thereof, wherein the modified asphalt comprises base asphalt and a modified asphalt additive; the modified asphalt additive comprises rubber powder, basalt fiber and lignin fiber; and the addition amounts of the rubber powder, the basalt fiber and the lignin fiber are 24.3%, 0.32% and 0.08% respectively. The application uses the response surface method (RSM) to perform statistical analysis, develop a prediction model and perform numerical optimization, determines a formula capable of achieving the maximum softening point within the content range of 15%-25% rubber powder, 0-0.4% basalt fiber and 0-0.4% lignin fiber, and provides a scientific basis for actual production, which is helpful to improve the quality and production efficiency of the modified asphalt.

Description

Technical Field

[0001] This invention belongs to the field of asphalt technology, specifically relating to a modified asphalt, its preparation method, and its application. Background Technology

[0002] Asphalt pavement is widely used in highways of all grades due to its excellent performance. However, with the rapid development of the transportation industry and the continuous increase in highway mileage, highways face complex geological environments and natural disasters, resulting in numerous disaster-causing factors and complex failure mechanisms. In particular, some surface asphalt roads suffer from problems such as low structural strength and poor durability. Under the influence of factors such as load, sunlight, precipitation, and temperature changes, they are prone to pavement defects such as cracking and collapse, seriously affecting driving safety.

[0003] The asphalt wearing course overlay technology, also known as ultra-thin wearing course technology, applied to the road surface, has the advantages of effectively repairing minor rutting and road surface cracking, while also improving skid resistance, reducing water spray, and facilitating construction. Its thickness is only 1 / 3 to 1 / 2 that of traditional wearing courses, saving 30% to 40% in construction and maintenance costs, and reducing resource and energy consumption.

[0004] Therefore, based on the current status and development needs of ultra-thin overlays, there is an urgent need to provide a new modified asphalt with better performance suitable for the above-mentioned technologies. Summary of the Invention

[0005] The purpose of this invention is to provide a modified asphalt, its preparation method and application. This invention modifies the matrix asphalt by selecting rubber powder, basalt and lignin composite fiber and participating in the optimization design of mixture gradation. Subsequently, various road performance indicators are verified to prove the practical applicability of ultra-thin wearing course.

[0006] The objective of this invention is achieved through the following technical solution: The present invention provides a modified asphalt, which includes a base asphalt and a modified asphalt additive.

[0007] Furthermore, the modified asphalt additive includes rubber powder, basalt fiber, and lignin fiber.

[0008] Furthermore, the amounts of adhesive powder, basalt fiber, and lignin fiber added are 24.3%, 0.32%, and 0.08%, respectively.

[0009] The present invention also provides a method for preparing the modified asphalt, comprising the following steps: (1) After heating the base asphalt to a liquid state, pour it into a container containing rubber powder; (2) After stirring evenly, heat to make the adhesive powder swell; (3) After swelling, continue stirring and control the temperature; (4) After mixing, add fiber and mix again. After heating, the modified asphalt is obtained.

[0010] Furthermore, in step (1), the heating is to heat the base asphalt at 170°C for 1.5 h, and the rubber powder accounts for 24.3% of the total mass of the raw materials.

[0011] Furthermore, in step (2), the stirring is to use a glass rod to stir so that the rubber powder is evenly dispersed in the asphalt, and the heating to make the rubber powder swell is to make the rubber powder swell in an oven at 170°C for 20 min.

[0012] Furthermore, in step (3), the continued stirring is to use a high-speed shear apparatus to stir at 5000 r / min for 20 min; the temperature control is to control the asphalt temperature to 185℃.

[0013] Furthermore, in step (4), the fiber is basalt fiber and lignin fiber, and the amount of basalt fiber and lignin fiber added accounts for 0.32% and 0.08% of the total mass of the raw materials, respectively; the heating is heating in an oven at 170℃ for 40 min.

[0014] The present invention also provides an application of the modified asphalt described above in road construction.

[0015] Furthermore, the road construction involves preparing an ultra-thin overlay layer for the road surface.

[0016] The beneficial effects of this invention are as follows: This invention modifies base asphalt by selecting rubber powder, basalt, and lignin composite fibers, effectively improving the road performance indicators of asphalt. Experiments show that the softening point of the modified asphalt generally increases, while the penetration generally decreases with increasing rubber powder content. This indicates that the high-temperature stability and hardness of the modified asphalt are improved, effectively resisting melting, damage, and load effects under high-temperature environments, thus reducing the occurrence of pavement distress.

[0017] This invention demonstrates that the addition of composite fibers significantly affects the penetration index (PI) of asphalt under different rubber powder dosages. As the rubber powder dosage increases, the PI value of the group with higher basalt fiber dosage tends to increase, indicating that the modified asphalt is less sensitive to ambient temperature, can adapt to a wider range of climatic conditions, and ensures the performance stability of the pavement under different temperatures.

[0018] This invention utilizes Response Surface Methodology (RSM) for statistical analysis, development of predictive models, and numerical optimization. It determined a formulation that maximizes the softening point within the range of 15%-25% rubber powder content, 0-0.4% basalt fiber content, and 0-0.4% lignin fiber content. Specifically, the rubber powder content is 24.3%, the basalt fiber content is 0.32%, and the lignin fiber content is 0.08%. This provides a scientific basis for actual production and helps improve the quality and production efficiency of modified asphalt.

[0019] The modified asphalt prepared by this invention is suitable for ultra-thin overlay technology for road surfaces. The thickness of the ultra-thin wearing course is only 1 / 3 to 1 / 2 of that of the traditional wearing course, which can save 30% to 40% of the construction and maintenance costs, reduce resource and energy consumption, and has good economic and social benefits. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 The diagram shows the modified asphalt additive product used in this invention, where a, b, and c are rubber powder, basalt fiber, and lignin fiber, respectively. Figure 2 This is a flowchart illustrating the preparation process of modified asphalt in this invention. Figure 3 This diagram shows the softening point of modified asphalt under different ratios of adhesive powder and fiber in this invention. Figure 4 This is a penetration diagram of modified asphalt with different ratios of rubber powder and fiber in this invention; Figure 5 This is a PI diagram of modified asphalt with different ratios of adhesive powder and fiber in this invention; Figure 6 This is a graph showing the normal distribution of data and the validity verification of the distribution in this invention. In the graph, a, b, and c are the normal distributions of softening point, penetration, and PI based on the data point distribution, respectively; d, e, and f are the residuals and running order of softening point, penetration, and PI, respectively. Figure 7 This is a comparison chart of the measured values ​​of different indicators and the predicted values ​​generated by the established model in this invention, where a, b, and c are the softening point, penetration, and PI, respectively. Figure 8This is a 3D surface plot showing the change in softening point of modified asphalt in this invention, where a, b, and c represent the relationship between the change in softening point of modified asphalt and the other two independent variables, respectively, when LF is constant, BF is constant, and RP is constant. Figure 9 This is a 3D surface plot showing the change in penetration of modified asphalt in this invention, where a, b, and c represent the relationship between the change in penetration of modified asphalt and the other two independent variables, respectively, when LF is constant, BF is constant, and RP is constant. Figure 10 This is a 3D surface plot showing the change of modified asphalt PI in this invention, where a, b, and c represent the relationship between the change of modified asphalt PI and the other two independent variables when LF is constant, BF is constant, and RP is constant, respectively. Detailed Implementation

[0022] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0023] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0024] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0025] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0026] The terms “comprising,” “including,” “having,” “containing,” etc., used in this document are all open-ended terms, meaning that they include but are not limited to. The proportions mentioned in the following embodiments are all mass ratios.

[0027] The present invention will be further illustrated below through examples.

[0028] Example 1 1. Raw material selection The base asphalt should be selected based on the climate, road surface grade, and other conditions of the region, and adjusted according to the region's experience in using asphalt in road paving. The selection should be finalized after technical testing. This embodiment uses Esso 70 Grade A road petroleum asphalt, whose technical indicators were determined according to relevant regulations. The main performance indicators are shown in Table 1.

[0029]

[0030] Rubber powder, basalt fiber, and lignin fiber were selected as modified asphalt additives. The rubber powder used in this embodiment was desulfurized waste tire rubber powder, which appeared as black powdery fine particles; basalt fiber was a natural mineral inorganic fiber; and lignin fiber was a white or grayish-white organic fiber. The specific morphologies of the rubber powder, basalt fiber, and lignin fiber are as follows: Figure 1 As shown in Table 2, the specific performance indicators of desulfurized rubber powder are shown in Table 3, and the specific performance indicators of lignocellulose are shown in Table 3.

[0031]

[0032]

[0033] 2. Experimental Methods 2.1 Preparation of Modified Asphalt Samples This embodiment focuses on the modification of base asphalt. Esso 70 Grade A road petroleum asphalt was selected as the base asphalt. The rubber powder content (RP) was divided into three gradients: 15%, 20%, and 25%. The ratio of basalt fiber to lignin fiber was controlled to be BF:LF = 0.4:0, 0.3:0.1, 0.2:0.2, 0.1:0.3, and 0:0.4, resulting in a total of 15 groups of modified asphalt.

[0034] To achieve suitable fluidity, the base asphalt was heated at 170℃ for 1.5 hours until it reached a liquid state, then poured into a container containing a pre-weighed amount of rubber powder. The mixture was quickly and thoroughly stirred with a glass rod to ensure the rubber powder was evenly dispersed in the asphalt. It was then placed in a 170℃ oven for 20 minutes to allow the rubber powder to swell. After swelling, the asphalt-rubber powder mixture was stirred at 5000 r / min for 20 minutes using a high-speed shear mixer. During stirring, the asphalt temperature was controlled at 185℃ using an electric furnace. After stirring, fibers were added to the asphalt-rubber powder mixture in multiple batches, stirring evenly in the same direction with a glass rod to disperse the fibers in the asphalt. After adding all the fibers, the asphalt was placed in a 170℃ oven for 40 minutes to obtain the final rubber powder-composite fiber modified asphalt. The three main indicators of the modified asphalt were measured on the same day. The specific preparation process is as follows: Figure 2 As shown.

[0035] 2.2 Determination of the physical properties of modified asphalt The modified asphalt obtained in step 2.1 was subjected to injection molding to test its softening point, penetration, and storage stability.

[0036] According to the standard T 0606-2011 in the JTG E20-2011 Highway Engineering Asphalt and Asphalt Mixture Test Procedure, the softening point (°C) of modified asphalt is tested using the ring and ball method. The softening point is selected when the asphalt can no longer support the weight of a 3.5g steel ball while still increasing in temperature at a uniform rate (5°C / min).

[0037] According to standard T 0604-2011 in the JTG E20-2011 Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering, a penetration test was conducted at 25℃ using a 100 g weight for 5 s. The penetration value of the modified asphalt sample was measured in units of 0.1 mm. Based on the penetration index parameter, the temperature sensitivity of base asphalt and modified asphalt was studied. The results of the penetration and softening point tests were used to estimate the penetration index PI using the following formula. Internationally, the most commonly used method is to calculate it using the penetration at 25℃ and the softening point, utilizing the linear relationship between the logarithm of penetration and temperature. The final calculation formula is as follows: ;

[0038] Where: A——the slope of the linear regression equation, the calculation method is shown in equation (2); — Penetration at 25℃ (100 g, 5 s); T – Measured softening point of asphalt (°C).

[0039] 2.3 Experimental Design and Response Surface Method (RSM) Analysis Techniques RSM is a statistical and mathematical method that can be used for experimental design, statistical analysis, modeling, and numerical optimization. Therefore, this embodiment selects RSM for statistical analysis, development of predictive models, and numerical optimization.

[0040] The numerical simulation software used in this embodiment is Design Expert 13. The effects of rubber powder, basalt fiber (BF), and lignin fiber (LF) on the softening point and penetration index of modified asphalt were investigated. According to the tests, the rubber powder content was 15%, 20%, and 25%, respectively. Too low a rubber powder content might not achieve the desired modification effect, while too high a content would result in an overly viscous asphalt paste, making shear dispersion difficult. Furthermore, excessive fiber would entangle the shearing device blade and cause the asphalt paste to become too viscous, hindering modification operations and subsequent testing of the three major indicators. Therefore, the total fiber content was controlled at 0.4% of the base asphalt mass, and the ratio of BF to LF was adjusted.

[0041] Experimental Example 1 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 25%, the amount of BF is 0%, and the amount of LF is 0.4%.

[0042] Experimental results: Softening point 62.4℃, penetration 44.5 (0.1mm), PI value 1.20.

[0043] Experimental Example 2 The preparation process of modified asphalt in this test example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this test example is 25%, the amount of BF is 0.4%, and the amount of LF is 0%.

[0044] Experimental results: softening point 63.1℃, penetration 42.3 (0.1mm), PI value 1.19.

[0045] Experimental Example 3 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 15%, the amount of BF is 0%, and the amount of LF is 0.4%.

[0046] Experimental results: softening point 60.5℃, penetration 56.8 (0.1mm), PI value 1.46.

[0047] Test Example 4 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 25%, the amount of BF is 0.2%, and the amount of LF is 0.2%.

[0048] Experimental results: softening point 62.9℃, penetration 44.1 (0.1mm), PI value 1.28.

[0049] Experimental Example 5 The preparation process of modified asphalt in this test example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this test example is 20%, the amount of BF is 0%, and the amount of LF is 0%.

[0050] Experimental results: softening point 61.4℃, penetration 45 (0.1mm), PI value 1.04.

[0051] Experimental Example 6 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 25%, the amount of BF is 0.3%, and the amount of LF is 0.1%.

[0052] Experimental results: softening point 63.1℃, penetration 43.9 (0.1mm), PI value 1.30.

[0053] Experimental Example 7 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 20%, the amount of BF is 0.1%, and the amount of LF is 0.3%.

[0054] Experimental results: softening point 62.4℃, penetration 45.6 (0.1mm), PI value 1.26.

[0055] Experimental Example 8 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 15%, the amount of BF is 0.3%, and the amount of LF is 0.1%.

[0056] Experimental results: softening point 60.9℃, penetration 45.8 (0.1mm), PI value 0.99.

[0057] Experimental Example 9 The preparation process of modified asphalt in this test example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this test example is 15%, the amount of BF is 0.4%, and the amount of LF is 0%.

[0058] Experimental results: softening point 61.9℃, penetration 44.4 (0.1mm), PI value 1.10.

[0059] Experimental Example 10 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 15%, the amount of BF is 0.1%, and the amount of LF is 0.3%.

[0060] Experimental results: softening point 60.7℃, penetration 55.5 (0.1mm), PI value 1.44.

[0061] Experimental Example 11 The preparation process of modified asphalt in this test example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this test example is 20%, the amount of BF is 0.4%, and the amount of LF is 0%.

[0062] Experimental results: softening point 62.9℃, penetration 43.6 (0.1mm), PI value 1.25.

[0063] Experimental Example 12 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 15%, the amount of BF is 0.2%, and the amount of LF is 0.2%.

[0064] Experimental results: softening point 60.7℃, penetration 48.9 (0.1mm), PI value 1.11.

[0065] Experimental Example 13 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 20%, the amount of BF is 0.3%, and the amount of LF is 0.1%.

[0066] Experimental results: softening point 62.8℃, penetration 44.2 (0.1mm), PI value 1.26.

[0067] Test Example 14 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 20%, the amount of BF is 0.2%, and the amount of LF is 0.2%.

[0068] Experimental results: softening point 62.5℃, penetration 44.9 (0.1mm), PI value 1.24.

[0069] Experimental Example 15 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 20%, the amount of BF is 0%, and the amount of LF is 0.4%.

[0070] Experimental results: softening point 62.2℃, penetration 47.4 (0.1mm), PI value 1.32.

[0071] Experimental Example 16 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 25%, the amount of BF is 0.1%, and the amount of LF is 0.3%.

[0072] Experimental results: softening point 62.7℃, penetration 44.1 (0.1mm), PI value 1.24.

[0073] Experimental Example 17 The preparation process of modified asphalt in this test example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this test example is 15%, the amount of BF is 0%, and the amount of LF is 0%.

[0074] Experimental results: softening point 60.5℃, penetration 48.9 (0.1mm), PI value 1.07.

[0075] Experimental Example 18 The preparation process of modified asphalt in this experimental example is the same as in Example 1. The only difference is that the amount of rubber powder (RP) in this experimental example is 25%, the amount of BF is 0%, and the amount of LF is 0%.

[0076] Experimental results: softening point 62.2℃, penetration 44.7 (0.1mm), PI value 1.18.

[0077] In the above experimental examples 1-18, a total of three factors were involved: rubber powder, BF, and LF. The rubber powder content was 15%, 20%, and 25% at three levels; the BF and LF content were each at five levels, and the total fiber content was 0.4% of the mass of the base asphalt. The final experimental results are shown in Table 4.

[0078]

[0079] Verification Example 1: Softening Point Experiment Asphalt viscosity and high-temperature stability can be reflected in the softening point. Based on the above experiments, the softening point variation trend of modified asphalt under different rubber powder and fiber ratios is as follows: Figure 3 As shown in Table 5, from Figure 3As shown in Table 5, the softening point of each fiber ratio group generally increases with the increase of rubber powder content. The softening point of the group without added fiber is approximately directly proportional to the rubber powder content. For the groups with added fiber, the increase in softening point is higher when the rubber powder content increases from 15% to 20%, and the increase slows down when the rubber powder content increases from 20% to 25%, but still maintains an upward trend. Overall, the softening point level of the fiber-added groups is higher than that of the group without added fiber. When the rubber powder content is 15%, BF has a higher effect on improving the softening point of modified asphalt than other groups, reaching 61.9℃; the other groups did not reach 61℃. This may be because BF disperses in the asphalt slurry and forms a stable structure by winding with RP, which slows down the dripping rate of the asphalt slurry when using the ring and ball method to test the softening point, resulting in a higher test result. When the rubber powder content was increased to 20%, the softening point of the modified asphalt was significantly improved compared to the control group without added fibers. However, the improvement effect was worse in the BF:LF=0.4:0 group compared to other fiber ratio groups. When the rubber powder content reached 25%, the improvement effect of each fiber ratio group on the softening point slowed down. It was noted that the softening point reached its maximum value of 63.1℃ when BF:LF=0.3:0.1. The softening point of the BF:LF=0:0.4 group was observed to be lower than that of other fiber-added groups, indicating that adding LF alone has limited effect on improving the softening point of modified asphalt, and the addition of BF is necessary. However, excessive BF, even with high rubber powder content, cannot achieve a good modification effect, and in actual engineering, it will affect the storage of asphalt mastic, increasing the difficulty of modification.

[0080]

[0081] Verification Example 1 1.1 Penetration Test The purpose of this test was to evaluate the consistency of rubber powder-composite fiber modified asphalt and the influence of rubber powder and composite fiber on asphalt hardness. The final results show the penetration of modified asphalt under different rubber powder and fiber ratios as follows: Figure 4 As shown in Table 6, from Figure 4As shown in Table 6, although the rubber powder-composite fiber modified asphalt is a heterogeneous asphalt mortar, the penetration index of each fiber ratio group generally shows a decreasing trend with the increase of rubber powder content. It can be seen that when the rubber powder content is 15%, the increase of BF content leads to a rapid decrease in the asphalt penetration value. The highest penetration value is found in the BF:LF=0:0.4 group, reaching 56.8, indicating that the asphalt mortar is relatively soft and easily penetrated by needles. The penetration value of the BF:LF=0:0.4 group remains at a high level with the increase of rubber powder content, indicating that the addition of LF has little effect on the hardness of the asphalt mortar. For modified asphalt ratio groups with higher BF content, especially the BF:LF=0.4:0 group, the penetration value remains at a low level, which is due to the high toughness and high density of BF leading to a higher mortar hardness. When the rubber powder content reaches 25%, the penetration value of the group without added fibers is higher, possibly because adding fibers when a large amount of rubber powder has already been added would affect the hardness of the asphalt mortar. Overall, the amount of rubber powder is the main factor affecting the change in asphalt penetration, and the increase in BF content will also have a certain impact on the reduction of modified asphalt penetration.

[0082]

[0083] 1.2 Temperature Sensitivity The purpose of this test is to evaluate the sensitivity of rubber powder-composite fiber modified asphalt to ambient temperature. The penetration of the modified asphalt under different rubber powder and fiber ratios is shown in the figure below. Figure 5 As shown in Table 7, from Figure 5 As shown in Table 7, the PI value of asphalt exhibits certain changes under different rubber powder contents. With increasing rubber powder content, the PI value of the group with higher basalt fiber content tends to increase. At the same rubber powder content, different composite fiber ratios have a significant impact on the PI value of asphalt. For example, at a rubber powder content of 15.0%, the PI value increases from 1.07 for 0% fiber to 1.46 for a 0:0.4 composite fiber ratio, demonstrating the moderating effect of the composite fiber ratio on the temperature sensitivity of asphalt. Therefore, by comparing the PI values ​​under different combinations, an asphalt formulation with the lowest temperature sensitivity under specific conditions can be selected.

[0084]

[0085] 1.3 Results of the Response Surface Method 1.3.1 Statistical Analysis and Analysis of Variance To verify the experimental results on the influence of rubber powder-composite fiber modified asphalt consistency, statistical analysis and response surface modeling were conducted under different rubber powder dosages and BF / LF composite ratios. This allows for the creation of more accurate predictive models of the behavior and fundamental rheological parameters of the rubber powder-composite fiber modifier. Based on regression analysis, quadratic and cubic polynomial models were used to represent the softening point, penetration, and PI of the control, rubber powder, BF, and LF composite modified asphalt. Appropriate polynomial regressions were evaluated based on the model's predicted and actual R² values ​​to represent the relationship between the rubber powder dosage and composite fiber ratio as inputs and the softening point, penetration, and PI as responses. Furthermore, other analyses, such as ANOVA, were performed to determine whether the recommended model was applicable to each response.

[0086] Tables 8-10 below list the ANOVA analysis results for softening point, penetration, and PI response, respectively. It can be seen that the F-values ​​for the three are 67.63, 19.44, and 5.76, respectively, indicating that the proposed model is statistically significant, and the probability that the F-values ​​are noise is extremely low, at 0.01%, 0.01%, and 1.08%, respectively. Furthermore, p-value analysis was used to assess the significance of the model within the 95% confidence interval. Tables 7-9 show that the p-values ​​for all models are below 0.05, indicating that the constructed model has a certain degree of significance within the 95% confidence interval.

[0087] The quality and fit of the models constructed in the study can be evaluated using their correlation coefficients (R²). In this example, the R² values ​​for softening point, penetration, and PI are 0.9836, 0.9453, and 0.8664, respectively. This indicates that all three models have a high degree of correlation. Furthermore, the Adj.R² values ​​for softening point, penetration, and PI are 0.9691, 0.8967, and 0.7161, respectively. This shows that the Adj.R² values ​​are very close to the expected R² values, meaning that the predictions obtained through this model match the data obtained from the laboratory study. The standard deviation (SD) and coefficient of variation (CV) of the model were used to evaluate the variability of the experimental data. Tables 7-9 show that all models have relatively low standard deviations and coefficients of variation (SD and CV), indicating that the created models are sufficiently correlated with the experimental data. According to the model design methodology, the precision (AP) value should be greater than 4. Clearly, Tables 8-10 show that the AP value for each model is greater than 4, meeting the standard requirement.

[0088]

[0089]

[0090]

[0091] Equations (3)-(5) illustrate the quadratic polynomial models for softening point, penetration, and PI derived from the ANOVA study. In the regression analysis, only significant and relatively significant terms were retained, while irrelevant variables with no or extremely insignificant impact on the results were discarded. Analysis of the following regression equations and their operational rules reveals the influence of rubber powder and composite fiber incorporation on the relevant properties and indices of asphalt. These equations can be used to predict the softening point, penetration, and PI indices of modified asphalt within the range of 15%-25% rubber powder incorporation, 0-0.4% BF, and 0-0.4% LF content.

[0092]

[0093] 1.3.2 Response Surface Contour Plot Diagnostic plots are drawn to determine the normality of the data and the validity of the distribution, specifically as follows: Figure 6 As shown. Figure 6 a, 6b, and 6c show the normal distributions of the softening point, penetration, and PI based on the data point distribution, respectively. The values ​​on the sloping lines are closely aligned with the normal plot of the residuals, indicating a high degree of consistency and suggesting that the data follows a normal distribution. Furthermore, Figure 6 Figures 6d, 6e, and 6f show the residuals and running order of the softening point, penetration, and PI, respectively. Except for one point in the PI graph that exceeds the red line, representing a deviation from the program, all other points are contained within the red boundary of the graph, indicating that the prediction model is established as expected.

[0094] To better understand the model's behavior and trends, a comparison chart was created between the measured values ​​of three indicators—softening point, penetration, and PI (Actual) and the predicted values ​​generated by the model. (See figure below.) Figure 7 As shown in the figure. The results show that the consistency and trend of the model predictions are basically consistent with the experimental results. The points representing the actual results are all distributed near the predicted line, which also demonstrates the accuracy of the model generated based on the experimental design layout. It can accurately predict the impact of changes in the content of rubber powder and BF and LF composite fibers on the thermal stability and consistency of asphalt.

[0095] Figures 8-10 These are 3D surfaces showing the changes in softening point, penetration, and PI of modified asphalt under different conditions. Figure 8Figures a, 8b, and 8c illustrate the relationship between the softening point of modified asphalt and the other two independent variables when LF, BF, and RP are kept constant (all at intermediate levels), respectively. The 3D graphs show a positive correlation between the softening point level and the RP and BF content. When the BF content is constant or fixed, the effect of LF on improving the softening point is limited. According to the prediction model, the highest softening point can be obtained when RP, BF, and LF all reach their set maximum levels. However, based on the tests conducted, the total fiber content needs to be controlled at 0.4% of the asphalt mass; therefore, further analysis of the maximum softening point value under this condition is required.

[0096] Figure 9 Figures 9a, 9b, and 9c show the influence of the other two independent variables on the penetration of modified asphalt when LF, BF, and RP are kept constant (all at intermediate levels), respectively. It can be seen that the decrease in penetration of modified asphalt is related to the increase of both BF and RP. This may be because the large incorporation of RP and BF produces a reinforcing effect, increasing the density of the modified asphalt mastic and leading to a decrease in penetration.

[0097] 1.4 Multi-objective optimization and prediction verification of response The softening point of modified asphalt reflects its high-temperature stability. In order to prevent asphalt pavement from melting or breaking under hot conditions or repeated rolling by vehicle wheels, asphalt pavement should have high high-temperature stability, which requires modified asphalt to have a high softening point.

[0098] pass Figures 8-10 It is known that the prediction model considers a total of 75 possibilities, including extreme cases such as 25% RP, 0.4% BF, and 0.4% LF. The softening point reaches its maximum value when both BF and LF are 0.4%, which clearly does not conform to actual production conditions. Therefore, the highest softening point is used as the target, and the total composite fiber content is artificially controlled to 0.4% of the asphalt mass. According to the model prediction results, the softening point reaches its maximum value of 63.28℃ when RP is 24.3%, BF is 0.32%, and LF is 0.08%. Under this ratio, the corresponding penetration is 43.20 and PI is 1.28.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit it. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of the present invention without departing from the spirit and scope of the technical solutions of the present invention, and all such modifications or substitutions should be covered within the scope of the claims of the present invention.

Claims

1. A modified bitumen, characterized in that, The modified asphalt includes base asphalt and modified asphalt additives; The modified asphalt additive includes desulfurized waste tire rubber powder, basalt fiber, and lignin fiber. The amounts of desulfurized waste tire rubber powder, basalt fiber, and lignin fiber added account for 24.3%, 0.32%, and 0.08% of the total mass of the raw materials, respectively.

2. The method of preparing modified bitumen according to claim 1, wherein, Includes the following steps: (1) After heating the base asphalt to a liquid state, pour it into a container containing desulfurized waste tire rubber powder; (2) After stirring evenly, heat to make the desulfurized waste tire rubber powder swell; (3) After swelling, continue stirring and control the temperature; (4) After mixing, add fiber and mix again. After heating, the modified asphalt is obtained.

3. The production method according to claim 2, wherein In step (1), the heating is to heat the base asphalt at 170°C for 1.5 h, and the desulfurized waste tire rubber powder accounts for 24.3% of the total mass of the raw materials.

4. The production method according to claim 2, wherein In step (2), the stirring is to use a glass rod to stir so that the desulfurized waste tire rubber powder is evenly dispersed in the asphalt, and the heating to make the desulfurized waste tire rubber powder swell is to make the desulfurized waste tire rubber powder swell in an oven at 170°C for 20 min.

5. The production method according to claim 2, wherein In step (3), the continued stirring is to use a high-speed shear apparatus to stir at 5000 r / min for 20 min; the temperature control is to control the asphalt temperature at 185℃.

6. The preparation method according to claim 2, characterized in that, In step (4), the fibers are basalt fibers and lignin fibers, and the amount of basalt fibers and lignin fibers added accounts for 0.32% and 0.08% of the total mass of the raw materials, respectively; the heating is carried out in an oven at 170°C for 40 min.

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