Urban inspection well periphery pavement repairing asphalt screening method based on high temperature stability

Abstract

The invention belongs to the technical field of road engineering materials, and provides a method for screening asphalt for repairing pavements around urban inspection wells based on high-temperature stability, which comprises the following steps of: firstly, selecting different types of asphalt samples special for repairing, and performing short-term aging treatment; secondly, performing a multiple stress creep recovery test to obtain the permanent deformation compliance of the special asphalt for repairing under different temperature, stress and aging conditions; then, a thermal activation rheological equation is used for fitting the relation changing along with the temperature, and thermal activation energy of all the special asphalt for repairing is obtained; a high-temperature stability index is defined and used for comprehensively evaluating the high-temperature rutting resistance of the repairing asphalt, and meanwhile, an aging attenuation coefficient is introduced and used for evaluating the influence of aging on the performance. According to the method, the temperature, the stress and the aging effect are uniformly incorporated into an analysis system through the thermal activation rheological model, so that the problems of single parameter and poor applicability in traditional high-temperature stability evaluation are solved, and the rheological property and the structural stability of the special asphalt for repairing in a high-temperature environment can be accurately reflected.

Description

Technical Field

[0001] This invention belongs to the field of road engineering materials technology, specifically relating to a method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability. Background Technology

[0002] The area around manholes is a weak point in urban roads due to factors such as material discontinuity, difficulty in compaction, and stress concentration. Repairs there are prone to secondary damage, severely impacting driving comfort and road lifespan. Therefore, developing specialized asphalt materials for manhole repair and establishing scientific evaluation methods for their high-temperature stability are of great significance for improving the overall service performance of urban roads.

[0003] Currently, both domestically and internationally, the composite shear modulus (G* / sinδ), zero shear viscosity (ZSV), and multiple stress creep recovery (MSCR) indicators obtained from the Superpave system are commonly used to evaluate the high-temperature stability of asphalt. These evaluation methods can reflect the high-temperature deformation resistance of repair-specific asphalt to a certain extent, but they still have the following shortcomings: (1) Existing evaluation systems are mostly based on single temperature or single stress conditions, which makes it difficult to truly reflect the performance changes of repair materials under the coupling effect of actual complex temperature and traffic load, and especially cannot accurately characterize their comprehensive response behavior under high temperature and multiple stress levels. (2) Traditional indicators fail to systematically consider the impact of short-term aging on the high-temperature performance of materials, making it difficult to predict the long-term durability of repair materials during actual construction and use. (3) Current methods rely on a single parameter and cannot simultaneously cover the coupling effect of multiple factors such as temperature, stress and aging. This results in a lack of consistency and comparability in the high-temperature stability ranking of different asphalts, which is not conducive to the scientific selection of repair materials.

[0004] In recent years, thermally activated rheological models have provided a new approach to characterizing the behavior of asphalt materials under multi-field coupling of temperature, stress, and aging. However, they have not yet been applied to the high-temperature stability evaluation and selection of asphalt specifically for repairing urban manholes. Therefore, there is an urgent need to establish a high-temperature stability evaluation method that can comprehensively consider the influence of multiple factors, providing a reliable basis for the accurate selection of repair materials and improving the quality of road repairs. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides a method for screening asphalt for repairing urban manhole perimeter pavements based on high-temperature stability, thereby resolving the issues in the prior art. The technical solution adopted by this invention is as follows: Asphalt selection methods for repairing urban manhole perimeter pavement based on high-temperature stability include: S1. Through multiple stress creep and recovery tests, the permanent deformation flexibility of repair-specific asphalt under different temperature, stress levels and aging conditions is obtained; S2. Establish a model of the relationship between permanent deformation compliance and temperature using the thermally activated rheological equation, and solve for the thermal activation energy. S3. Calculate the stress response coefficient of the repair-specific asphalt under different stress levels; S4. Construct a high-temperature stability index; S5. Calculate the aging attenuation coefficient based on the high temperature stability index and evaluate the anti-aging ability of the repair asphalt.

[0006] Furthermore, in S2, a model relating permanent deformation compliance to temperature is established using the thermally activated rheological equation, including: The thermally activated rheological equation is expressed as: ; In the formula: The constant is the permanent deformation compliance; A is a constant term. R is the thermal activation energy; T is the gas constant; and T is the absolute temperature. Taking the logarithm of both sides of the thermally activated rheological equation, we obtain a linear expression: ; make , The resulting linear equation is: ; in, , .

[0007] Furthermore, in S2, solving for the thermal activation energy includes: Based on multiple stress creep and recovery tests at different temperatures Data, with As the independent variable, Using the least squares method as the dependent variable, linear regression is performed to obtain the slope. With intercept Thus, the thermal activation energy can be calculated. .

[0008] Furthermore, in S3, the stress response coefficient is obtained by the slope of the permanent deformation compliance as a function of stress, and is expressed as: ; We obtain the following by differentiating the stress yield: ; In the formula: The stress response coefficient; For permanent deformation flexibility; The applied stress level; Let be the intercept of the linear equation.

[0009] Furthermore, the characteristic feature is that, in S4, the formula for constructing the high-temperature stability index is: ; In the formula, The average thermal activation energy, The mean permanent deformation compliance at the highest temperature. The average stress response coefficient, This is the high-temperature stability index.

[0010] Furthermore, in S5, the aging attenuation coefficient is the ratio of the high-temperature stability index under unaged and aged conditions, used to evaluate the impact of aging on the performance of repair-specific asphalt; the aging attenuation coefficient is expressed as: ; in, This is the aging degradation coefficient; the smaller the value, the greater the aging effect. The high-temperature stability index is calculated for repairing asphalt under aged conditions; The high-temperature stability index is calculated for repairing asphalt in its unaged state.

[0011] The present invention has the following beneficial effects: (1) Strong comprehensiveness: This invention establishes a temperature-dependent equation based on a thermally activated rheological model, which integrates three key factors—temperature, stress level, and aging state—into the analysis system. This overcomes the limitations of traditional methods that only evaluate under a single temperature or stress condition, and can comprehensively reflect the mechanical response characteristics of repair-specific asphalt materials under high-temperature conditions.

[0012] (2) The model is scientific and reasonable: This invention establishes a temperature-dependent model by introducing a thermally activated rheological equation, so that the thermally activated energy Q has a clear physical meaning and can effectively quantify the temperature sensitivity of repaired asphalt.

[0013] (3) Objective and unified evaluation results: This invention achieves comparability of different repair asphalts in terms of high temperature stability by defining a unified high temperature stability index (HSI), thus avoiding errors caused by inconsistent parameters in the traditional index system.

[0014] (4) The effects of aging can be quantified: The present invention introduces the aging attenuation coefficient AAC, which can quantitatively evaluate the attenuation law of short-term aging on high-temperature stability, and provide a scientific basis for the aging sensitivity analysis of repair asphalt materials. Attached Figure Description

[0015] Figure 1 Here is the overall method flowchart; Figure 2 This refers to the Sr value of all repair-specific asphalt in its unaged state; Figure 3 This represents the Sr value of all repair-specific asphalt under aged conditions. Detailed Implementation

[0016] The following will be described in conjunction with embodiments of the present invention. Figures 1-3 The technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Unless otherwise specified, the technical means used in the embodiments are conventional means well known to those skilled in the art.

[0017] This invention first selects different types of repair-specific asphalt samples and subjects them to short-term aging treatment. Second, it conducts multiple stress creep recovery tests to obtain the permanent deformation compliance of the repair-specific asphalt under different temperature, stress, and aging conditions. Then, it uses a thermally activated rheological equation to fit the relationship with temperature changes, obtaining the thermal activation energy of each repair-specific asphalt to characterize its temperature sensitivity. Combined with the stress response coefficient, a high-temperature stability index is defined to comprehensively evaluate the high-temperature rutting resistance of the repair asphalt. Simultaneously, an aging attenuation coefficient is introduced to evaluate the impact of aging on performance. This invention's method integrates temperature, stress, and aging effects into the analysis system through a thermally activated rheological model, overcoming the problems of single parameters and poor applicability in traditional high-temperature stability evaluations. It accurately reflects the rheological characteristics and structural stability of repair-specific asphalt under high-temperature environments, providing a scientific basis for the optimal selection of repair-specific asphalt for urban manhole perimeter pavement repair. This method is simple to calculate and yields reliable results, and can be widely applied to the high-temperature stability evaluation and formulation optimization of special asphalt materials in urban road repair projects.

[0018] Specifically, such as Figure 1 This invention proposes a method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability, comprising: S1. Through multiple stress creep and recovery tests, the permanent deformation flexibility of repair-specific asphalt under different temperature, stress levels and aging conditions is obtained; S2. Establish a model of the relationship between permanent deformation compliance and temperature using the thermally activated rheological equation, and solve for the thermal activation energy. S3. Calculate the stress response coefficient of the repair-specific asphalt under different stress levels; S4. Construct a high-temperature stability index; S5. Calculate the aging attenuation coefficient based on the high temperature stability index and evaluate the anti-aging ability of the repair asphalt.

[0019] Among them, the Multiple Stress Creep and Recovery (MSCR) test is an existing technology. It involves conducting multiple stress creep recovery tests on asphalt samples under different temperatures and stress levels, respectively, after unaged and short-term aged (RTFOT) treatments, to measure the permanent deformation compliance under different temperatures, stress levels and aging conditions.

[0020] Furthermore, in S2, a model relating permanent deformation compliance to temperature is established using the thermally activated rheological equation, including: The thermally activated rheological equation is expressed as: ; In the formula: The constant is the permanent deformation compliance; A is a constant term. R is the thermal activation energy; T is the gas constant; and T is the absolute temperature. Taking the logarithm of both sides of the thermally activated rheological equation, we obtain a linear expression: ; make , The resulting linear equation is: ; in, , .

[0021] Furthermore, in S2, solving for the thermal activation energy includes: Based on multiple stress creep and recovery tests at different temperatures Data, with As the independent variable, Using the least squares method as the dependent variable, linear regression is performed to obtain the slope. With intercept Thus, the thermal activation energy can be calculated. .

[0022] Furthermore, in S3, the stress response coefficient is obtained by the slope of the permanent deformation compliance as a function of stress, and is expressed as: ; We obtain the following by differentiating the stress yield: ; In the formula: The stress response coefficient; For permanent deformation flexibility; The applied stress level; Let be the intercept of the linear equation.

[0023] Furthermore, the characteristic feature is that, in S4, the formula for constructing the high-temperature stability index is: ; In the formula, The average thermal activation energy, The mean permanent deformation compliance at the highest temperature. The average stress response coefficient, This is the high-temperature stability index.

[0024] Furthermore, in S5, the aging attenuation coefficient is the ratio of the high-temperature stability index under unaged and aged conditions, used to evaluate the impact of aging on the performance of repair-specific asphalt; the aging attenuation coefficient is expressed as: ; in, This is the aging degradation coefficient; the smaller the value, the greater the aging effect. The high-temperature stability index is calculated for repairing asphalt under aged conditions; The high-temperature stability index is calculated for repairing asphalt in its unaged state.

[0025] The following section uses six types of special asphalt used in a manhole repair project on a main road in a certain city as an example to illustrate the method of the present invention in detail. The road section in this project is located in a high-temperature area in summer, where the surface temperature can reach above 60°C all year round. Asphalt pavement is subjected to high temperature and heavy load for a long time, which easily leads to permanent deformation problems such as rutting.

[0026] Based on the rheological performance test results under the multi-stress creep recovery (MSCR) test conditions, and combined with the actual characteristics of the road structure layer in this region under high temperature, the preferred method for repairing pavement around urban manholes proposed in this invention is further explained.

[0027] The specific steps of this method are as follows: S1: Select asphalt samples suitable for repairing urban manholes, and define them as No. 1, No. 2, No. 3, No. 4, No. 5 and No. 6 respectively. After unaged and short-term aging (RTFOT) treatments, conduct multiple stress creep and recovery (MSCR test) tests.

[0028] The experiment was conducted on a dynamic shear rheometer (DSR). Four temperature points—40 ℃, 50 ℃, 60 ℃, and 70 ℃—were selected to cover the high-temperature range commonly found in engineering pavements. The applied stress levels were set to 3.2 kPa, 5.0 kPa, 8.0 kPa, and 10.0 kPa to simulate the stress response characteristics of asphalt materials under different traffic loads.

[0029] The repair asphalt was measured under different temperatures, stress levels, and aging conditions. Dp The values ​​were calculated, and the average of each set of data was taken as the representative result under that condition. Tables 1, 2, 3, and 4 show the measured values ​​of the unaged repair-specific asphalt under different stress and temperature levels. Dp The results, Tables 5, 6, 7, and 8, show the measured values ​​of the aging repair-specific asphalt under different stress and temperature levels. Dp result.

[0030] Table 1. Special Asphalt for Repairing Unaged Asphalt at 3.2 kPa Dp

[0031] Table 2. Special Asphalt for Repairing Unaged Asphalt at 5 kPa Dp

[0032] Table 3. Special Asphalt for Repairing Unaged Bituminous Material at 8 kPa Dp

[0033] Table 4. Special Asphalt for Repairing Unaged Asphalt at 10KPa Dp

[0034] Table 5. Special Asphalt for Aging Repair at 3.2 kPa Dp

[0035] Table 6. Special Asphalt for Aging Repair at 5KPa Dp

[0036] Table 7. Special Asphalt for Aging Repair at 8 kPa Dp

[0037] Table 8. Special Asphalt for Aging Repair at 10 kPa Dp

[0038] S2: This step utilizes a thermally activated rheological model to quantitatively characterize the temperature sensitivity of the repair-specific asphalt. The thermally activated rheological model is an important empirical equation describing the thermal activation process of materials, and its form can be expressed as: ; In the formula: For permanent deformation compliance ( A is a constant term that reflects the structural properties of the material. Thermally activated energy ( ), representing the sensitivity of the material's rheological properties to temperature changes; R is the gas constant (8.314 = T is the absolute temperature ( ).

[0039] To facilitate linear fitting, we take the logarithm of both sides of the above equation, and obtain the following linear expression: ; make , The resulting linear equation is as follows: ; in, , .

[0040] Based on the results of multiple stress creep and recovery tests at different temperatures Data, with As the independent variable, Using the least squares method as the dependent variable, linear regression is performed to obtain the slope. With intercept Therefore, the thermal activation energy can be calculated. .

[0041] ; To verify the applicability of the thermally activated rheological model, this invention calculates the stress levels of each repair asphalt at four stress levels (3.2). 5 8 10 Coefficient of determination for fit under ) All fitting results All are greater than 0.93, indicating and The significant linear correlation between the two indicates that the rheological properties of the repair-specific asphalt in the high-temperature range conform to the thermally activated rheological law.

[0042] Calculations show that the thermal activation energy of different types of repair-specific asphalt varies between aged and non-aged states. As shown in Table 9 below.

[0043] Table 9. Q values ​​of all repair-specific asphalts under unaged and aged conditions.

[0044] S3: Obtaining permanent deformation compliance under different stress levels Following the data, to further quantify the response of repair asphalt to applied stress, this step calculates the stress response coefficient. Sr The stress response coefficient reflects the degree of rheological nonlinearity of repair asphalt at high temperatures and is an important characterization parameter for its high-temperature rutting resistance.

[0045] Based on the results of the multiple stress creep recovery (MSCR) test, For the ordinate, Using the x-axis as the horizontal axis, a linear regression fit is performed to establish the following relationship: ; In the formula, For permanent deformation compliance ( ); The applied stress level ( ); This is the intercept of the linear equation; The slope of this linear equation is the stress response coefficient defined in this invention at that specific temperature. ).

[0046] Differentiate the preceding equation with respect to stress yield: ; By performing a linear fit using the least squares method on the established linear relationship, the stress response coefficient under specific conditions (specific asphalt, specific aging state, specific temperature) can be obtained. Sr The value of . Sr The magnitude of the value directly represents Dp Sensitivity to stress changes. Sr The larger the value, the greater the stress for each unit increase. Dp The greater the increase, the more sensitive the repair asphalt is to heavy traffic, the less stable its network structure is under high pressure, and the higher the risk of deterioration in its rutting resistance. Under different conditions... Sr Values ​​such as Figure 2 and Figure 3 .

[0047] To ensure data stability, this invention calculates data at each test temperature. Sr Take four temperatures Sr The average value is used as the comprehensive stress sensitivity index of the repaired asphalt.

[0048] This average value is the average stress response coefficient of the repair-specific asphalt under this aging state, denoted as . .

[0049]

[0050] Table 10 Stress response coefficients of different repair-specific asphaltsSr

[0051] S4: The deformation properties of asphalt under high-temperature loads are controlled by both temperature and stress effects. Thermal activation energy. This describes the material's sensitivity to temperature changes; a higher value indicates a stronger resistance to temperature variations. The stress response coefficient reflects a material's ability to recover from deformation under high temperature and high stress. A smaller value indicates lower fluidity and stronger resistance to deformation. Sr This is used to describe the degree of response of a material to changes in applied stress. To achieve optimal performance for repaired asphalt, this invention constructs a high-temperature stability index. HSI Its definition is as follows: ; In the formula, The average thermal activation energy, The mean permanent deformation compliance at the highest temperature. This represents the average stress sensitivity.

[0052] The upper horizontal bar above the parameters represents the average value. The unit of the high temperature stability index is ( ). A higher high-temperature stability index indicates better rutting resistance. Table 11 below shows the high-temperature stability index of all repair-specific asphalts under both unaged and aged conditions.

[0053] Table 11 High-Temperature Stability Index of Different Repair-Specific Asphalts

[0054] The results showed that No. 3, No. 4, and No. 6 repair asphalts had significantly higher [performance / quality]. HSI The values ​​show excellent high-temperature rutting resistance. Among them, No. 4 has the highest high-temperature stability index in both unaged and aged states, indicating that its polymer network structure is more stable under high-temperature conditions and has the strongest resistance to rheological deformation under the coupling effect of temperature and stress.

[0055] S5: Achieves a high-temperature stability index for repair asphalt. Next, to further evaluate the magnitude of performance changes and durability of the material under aging, this step introduces the aging degradation coefficient (AAC). The aging degradation coefficient is used to quantify the degree of retention of high-temperature stability before and after aging, and its definition is as follows: ; In the formula, The aging degradation coefficient (dimensionless) reflects the relative degree of performance change before and after aging; The high-temperature stability index is calculated for repairing asphalt under aged conditions; The high-temperature stability index is calculated for repairing asphalt in its unaged state.

[0056] The AAC value reflects the degree of influence of aging on the high-temperature deformation resistance of asphalt. The smaller the AAC, the more significant the decline in high-temperature stability of asphalt after aging; conversely, the closer the AAC is to 1, the better the material can maintain good rutting resistance after aging.

[0057] The specific indicators are shown in Table 12 below.

[0058] Table 12 Aging Degradation Coefficients of Different Repair-Specific Asphalts

[0059] According to the data in Table 12, No. 4 asphalt has the lowest AAC value but the highest HSI value, indicating that although it is more sensitive to aging, it has extremely strong high-temperature deformation resistance. No. 1 and No. 2 asphalt have relatively high AAC values, indicating that their performance stability is good but their overall rutting resistance is average. No. 5 and No. 6 asphalt show obvious performance differentiation after aging. Among them, the HSI value of No. 6 asphalt increases significantly after aging, indicating that its structure is more compact and its thermal stability is significantly improved after aging.

[0060] The overall high-temperature stability index ranking is as follows: No. 6 > No. 4 > No. 5 > No. 3 > No. 2 > No. 1. This ranking result indicates that the parameters obtained by this method can accurately reflect the stability and rutting resistance of different repair-specific asphalt materials under high-temperature conditions.

[0061] In summary, the proposed method for optimizing asphalt for urban manhole perimeter road repair based on high-temperature stability is feasible. This method enables unified quantitative analysis of temperature, stress, and aging factors, overcoming the limitations of traditional indicators (such as G* / sinδ, ZSV, etc.) that characterize performance only under single conditions. It is applicable to engineering practices such as the research and development of asphalt for urban manhole perimeter road repair, material selection, and road maintenance engineering design, providing reliable theoretical and technical support for the anti-rutting repair design and performance optimization of urban road manhole perimeter areas in high-temperature regions. This invention can be applied to new material-related services in roads, bridges, and buildings; new material testing; computer-aided design; testing or analyzing materials by measuring their chemical or physical properties; road construction materials; applying thermal methods to test or analyze materials; and related industries such as infrastructure digital data processing.

[0062] The above embodiments are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, alterations, alterations, or substitutions made by those skilled in the art to the technical solutions of the present invention without departing from the spirit of the present invention should fall within the protection scope defined by the claims of the present invention.

Claims

1. A method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability, characterized in that, include: S1. Through multiple stress creep and recovery tests, the permanent deformation flexibility of repair-specific asphalt under different temperature, stress levels and aging conditions is obtained; S2. Establish a model of the relationship between permanent deformation compliance and temperature using the thermally activated rheological equation, and solve for the thermal activation energy. S3. Calculate the stress response coefficient of the repair-specific asphalt under different stress levels; S4. Construct a high-temperature stability index; S5. Calculate the aging attenuation coefficient based on the high temperature stability index and evaluate the anti-aging ability of the repair asphalt.

2. The method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability according to claim 1, characterized in that, In S2, a model relating permanent deformation compliance to temperature is established using thermally activated rheological equations, including: The thermally activated rheological equation is expressed as: ； In the formula: The constant is the permanent deformation compliance; A is a constant term. R is the thermal activation energy; T is the gas constant; and T is the absolute temperature. Taking the logarithm of both sides of the thermally activated rheological equation, we obtain a linear expression: ； make , The resulting linear equation is: ； in, , .

3. The method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability according to claim 2, characterized in that, In S2, solving for the thermal activation energy includes: Based on multiple stress creep and recovery tests at different temperatures Data, with As the independent variable, Using the least squares method as the dependent variable, linear regression is performed to obtain the slope. With intercept Thus, the thermal activation energy can be calculated. .

4. The method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability according to claim 2, characterized in that, In S3, the stress response coefficient is obtained by the slope of the permanent deformation compliance as a function of stress, and is expressed as: ； We obtain the following by differentiating the stress yield: ； In the formula: The stress response coefficient; For permanent deformation flexibility; The applied stress level; Let be the intercept of the linear equation.

5. The method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability according to any one of claims 1-4, characterized in that, In S4, the formula for constructing the high-temperature stability index is: ； In the formula, The average thermal activation energy, The mean permanent deformation compliance at the highest temperature. The average stress response coefficient, This is the high-temperature stability index.

6. The method for screening asphalt for repairing urban manhole perimeter pavement based on high-temperature stability according to claim 5, characterized in that, In S5, the aging attenuation coefficient is the ratio of the high-temperature stability index under unaged and aged conditions, used to evaluate the impact of aging on the performance of repair-specific asphalt; the aging attenuation coefficient is expressed as: ； in, This is the aging degradation coefficient; the smaller the value, the greater the aging effect. The high-temperature stability index is calculated for repairing asphalt under aged conditions; The high-temperature stability index is calculated for repairing asphalt in its unaged state.

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