A rapid prediction method of zero shear viscosity of matrix asphalt based on dynamic shear modulus master curve

Abstract

The application discloses a kind of based on dynamic shear modulus master curve matrix asphalt zero shear viscosity fast prediction method, the method is obtained under the condition of multiple temperature, multiple frequency of complex modulus of asphalt by dynamic shear rheological test, and equivalent principle of time-temperature is combined to construct dynamic shear modulus master curve;On this basis, modulus-viscosity conversion relationship is used to establish complex viscosity master curve, by comparing the complex viscosity under low frequency condition with the steady-state apparent viscosity under low shear rate condition, determine the equivalent application interval of Cox-Merz relationship established;Further in the interval, using rheological model is fitted to complex viscosity master curve, obtain the zero shear viscosity of asphalt.The application can realize the fast, stable prediction of zero shear viscosity based on dynamic shear test, and can reuse existing dynamic shear modulus master curve data, with the advantages of high test efficiency, strong engineering applicability.

Description

Technical Field

[0001] This invention belongs to the field of rheological testing technology for asphalt materials, and relates to a method for characterizing the rheological properties of asphalt materials, specifically a method for rapid prediction of zero-shear viscosity of matrix asphalt based on the master curve of dynamic shear modulus. Background Technology

[0002] Zero shear viscosity (ZSV) is a key rheological parameter characterizing the flow properties of asphalt under high temperature and low shear conditions, and is closely related to its high-temperature rutting resistance and service stability. In existing technologies, zero shear viscosity is typically determined through steady-state shear rheological tests under low shear rate conditions. However, this method is time-consuming and prone to shear instability and test fluctuations under low shear conditions, resulting in poor repeatability and reliability of the results.

[0003] In contrast, dynamic shear rheological testing offers advantages such as controllable strain, high testing stability, and high testing efficiency. By establishing a master curve of dynamic shear modulus through multi-temperature and multi-frequency scanning combined with the time-temperature equivalence principle, the viscoelastic properties of asphalt can be systematically characterized. Studies have shown that, under certain conditions, there is an equivalent relationship between the complex viscosity obtained from dynamic shear testing and the apparent viscosity obtained from steady-state shear testing, namely the Cox-Merz relationship.

[0004] However, existing technologies often apply the Cox-Merz relationship directly based on experience, lacking a clearly defined applicable range. This leads to uncertainty in predicting zero-shear viscosity based on dynamic shear tests. Furthermore, a large amount of dynamic shear modulus master curve data has not yet been effectively used to obtain zero-shear viscosity. Therefore, there is an urgent need for a method based on the dynamic shear modulus master curve that can clearly define the applicable range of the Cox-Merz relationship and achieve rapid and stable prediction of zero-shear viscosity in base asphalt. Summary of the Invention

[0005] To address the problems of long testing time and insufficient stability in existing steady-state shear tests for determining zero-shear viscosity, this invention provides a rapid prediction method for the zero-shear viscosity of base asphalt based on the dynamic shear modulus master curve. This method establishes the dynamic shear modulus master curve of asphalt through dynamic shear tests, or extracts existing dynamic shear modulus master curve data from literature, converts it to a complex viscosity master curve, verifies the result, and rapidly calculates the zero-shear viscosity of asphalt using the Cox-Merz relationship. This invention enables rapid and stable prediction of zero-shear viscosity based on dynamic shear tests and allows for the reuse of existing dynamic shear modulus master curve data, offering advantages such as high testing efficiency and strong engineering applicability.

[0006] The objective of this invention is achieved through the following technical solution:

[0007] A rapid prediction method for zero-shear viscosity of base bitumen based on the master curve of dynamic shear modulus includes the following steps:

[0008] Step 1: Dynamic frequency scanning tests were conducted on asphalt using a dynamic shear rheometer. The complex modulus of asphalt at a reference temperature of 60℃ was established based on the time-temperature equivalence principle. Storage modulus and loss modulus Principal curve;

[0009] Step 2: Obtain the dynamic viscosity through the modulus-viscosity conversion relationship. Loss viscosity and complex viscosity Main curve:

[0010]

[0011]

[0012]

[0013] Step 3: Conduct steady-state flow scanning tests on asphalt using a dynamic shear rheometer to establish the steady-state apparent viscosity curve of asphalt;

[0014] Step 4: By comparing the complex viscosity under low-frequency conditions with the steady-state apparent viscosity under low-shear rate conditions, determine the equivalent applicable range for the Cox-Merz relationship. The Cox-Merz relationship is as follows:

[0015]

[0016] In the formula, Shear rate; The apparent viscosity for steady-state testing; Angular frequency; Complex viscosity for dynamic testing;

[0017] Step 5: Within the equivalent applicable interval where the Cox-Merz relationship holds as determined in Step 4, obtain the zero-shear viscosity using the complex viscosity master curves fitted by the Cross and Carreau models, respectively. The formulas for the Cross and Carreau models are as follows:

[0018]

[0019]

[0020] In the formula, Viscosity; This is the first Newtonian viscosity, i.e., the zero-shear viscosity; This refers to the viscosity in the second Newtonian zone of the flow curve. , denoted as a characteristic constant of the material.

[0021] In this invention, steps one and two can be replaced by: extracting existing dynamic shear modulus master curve data from the literature and converting it to obtain the complex viscosity master curve.

[0022] Compared with the prior art, the present invention has the following advantages:

[0023] 1. This invention uses dynamic shear testing to replace steady-state shear testing, enabling rapid prediction of the zero-shear viscosity of base asphalt. While shortening the testing time and improving testing efficiency, it effectively avoids shear instability problems through strain-controllable testing methods, thereby improving the stability and repeatability of test results.

[0024] 2. By verifying the applicability of the Cox–Merz relationship and defining the low-frequency range, the prediction process of zero shear viscosity has clear technical boundaries and implementation conditions, avoiding the uncertainty brought about by empirical relationships.

[0025] 3. This invention can be implemented using only conventional dynamic shear rheology tests without the need for additional testing equipment. At the same time, for base asphalt with obtained dynamic shear modulus master curves, its zero-shear viscosity can be directly predicted without additional tests, thus fully exploring the engineering application value of existing test data. Attached Figure Description

[0026] Figure 1 A comparison chart of steady-state shear viscosity curve and dynamic shear viscosity master curve;

[0027] Figure 2 To obtain the zero-shear viscosity map using a Cross model fitting. Detailed Implementation

[0028] The technical solution of the present invention will be further described below with reference to the accompanying drawings, but it is not limited thereto. Any modifications or equivalent substitutions to the technical solution of the present invention that do not depart from the spirit and scope of the technical solution of the present invention should be covered within the protection scope of the present invention.

[0029] This invention provides a rapid prediction method for the zero-shear viscosity of base asphalt based on a dynamic shear modulus master curve. The method obtains the complex modulus of asphalt under multiple temperature and frequency conditions through dynamic shear rheological tests, and constructs a dynamic shear modulus master curve using the time-temperature equivalence principle. Based on this, a complex viscosity master curve is established using the modulus-viscosity conversion relationship. By comparing the complex viscosity under low-frequency conditions with the steady-state apparent viscosity under low shear rate conditions, the equivalent applicable interval for the Cox-Merz relationship is determined. Then, within this interval, a rheological model is used to fit the complex viscosity master curve to obtain the zero-shear viscosity of the asphalt. This method aims to solve the problems of long testing time and insufficient stability in existing steady-state shear tests for determining zero-shear viscosity. The specific steps are as follows:

[0030] Step 1: Conduct dynamic frequency sweep tests on asphalt using a dynamic shear rheometer (temperatures 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃, and 70℃, angular frequency 100~0.01 rad / s). Based on the time-temperature equivalence principle, establish the complex modulus of asphalt at a reference temperature of 60℃. Storage modulus () and loss modulus ( Main curve.

[0031] Step 2: Obtain the dynamic viscosity through the modulus-viscosity conversion relationship. ), loss viscosity ( ) and complex viscosity ( Main curve:

[0032]

[0033]

[0034]

[0035] In the formula: To store modulus, For loss modulus, For complex viscosity, For dynamic viscosity, This is for loss viscosity.

[0036] Step 3: Conduct steady-state flow sweep tests on asphalt using a dynamic shear rheometer (temperature 60℃, shear rate 0.001~1000 s⁻¹). - ¹), establish the steady-state apparent viscosity curve of asphalt.

[0037] Step 4: By comparing the complex viscosity master curve and the steady-state apparent shear viscosity curve under conditions where the angular frequency and shear rate are of comparable magnitude (e.g., ...Figure 1 As shown in the figure, when the angular frequency and shear rate are in the low range, both types of viscosity curves form a stable zero-shear viscosity plateau, and the viscosity values ​​within the corresponding plateau interval are highly consistent, indicating that the Cox-Merz relationship is stably valid in this range. Therefore, this low-frequency, low-shear-rate range is determined as the equivalent applicable range of the Cox-Merz relationship, for subsequent direct characterization of the zero-shear viscosity of asphalt based on dynamic shear tests. The Cox-Merz relationship is as follows:

[0038]

[0039] In the formula, Shear rate ( / s); The apparent viscosity (Pa·s) is for steady-state testing. Angular frequency (rad / s); The complex viscosity (Pa·s) is measured dynamically.

[0040] Step 5: Within the Cox-Merz equivalent applicability range determined in Step 4, fit the steady-state apparent viscosity curve and the complex viscosity master curve using the Cross model and Carreau model respectively (e.g., Figure 2 As shown in the figure, the corresponding zero-shear viscosity is obtained from the fitting results. The results show that the zero-shear viscosity obtained based on the fitting of the complex viscosity master curve has good consistency with the zero-shear viscosity obtained based on the fitting of the steady-state apparent viscosity curve, thus indicating that the method of the present invention can obtain reliable zero-shear viscosity results without the need for steady-state shear tests.

[0041] The formulas for the Cross and Carreau models are as follows:

[0042]

[0043]

[0044] In the formula, Viscosity (Pa·s); This is the first Newtonian viscosity, i.e., the zero-shear viscosity (Pa·s); The viscosity (Pa·s) in the second Newtonian zone of the flow curve. The shear rate is 1 / s. , denoted as a characteristic constant of the material.

Claims

1. A rapid prediction method for zero-shear viscosity of base bitumen based on the master curve of dynamic shear modulus, characterized in that... The method includes the following steps: Step 1: Dynamic frequency scanning tests were conducted on asphalt using a dynamic shear rheometer. The complex modulus of asphalt at a reference temperature of 60℃ was established based on the time-temperature equivalence principle. Storage modulus and loss modulus Principal curve; Step 2: Obtain the dynamic viscosity through the modulus-viscosity conversion relationship. Loss viscosity and complex viscosity Principal curve; Step 3: Conduct steady-state flow scanning tests on asphalt using a dynamic shear rheometer to establish the steady-state apparent viscosity curve of asphalt; Step 4: By comparing the complex viscosity under low frequency conditions with the steady-state apparent viscosity under low shear rate conditions, determine the equivalent applicable range in which the Cox–Merz relationship holds. Step 5: Within the equivalent applicable range where the Cox–Merz relationship is valid as determined in Step 4, obtain the zero-shear viscosity using the complex viscosity master curves fitted by the Cross and Carreau models, respectively.

2. The method for rapid prediction of zero-shear viscosity of base asphalt based on the master curve of dynamic shear modulus according to claim 1, characterized in that... In step one, the temperature for the frequency scanning test is 0℃, 10℃, 20℃, 30℃, 40℃, 50℃, 60℃ and 70℃, and the angular frequency is 100~0.01 rad / s.

3. The method for rapid prediction of zero-shear viscosity of base asphalt based on the master curve of dynamic shear modulus according to claim 1, characterized in that... In step two, dynamic viscosity Loss viscosity and complex viscosity The calculation formula is: 。 4. The method for rapid prediction of zero-shear viscosity of base bitumen based on the master curve of dynamic shear modulus according to claim 1, characterized in that... In step three, the flow scanning test temperature is 60℃, and the shear rate is 0.001~1000 s⁻¹. - ¹.

5. The method for rapid prediction of zero-shear viscosity of base asphalt based on the master curve of dynamic shear modulus according to claim 1, characterized in that... In step four, the Cox–Merz relationship is as follows: In the formula, Shear rate; The apparent viscosity for steady-state testing; Angular frequency; For complex viscosity tested dynamically.

6. The method for rapid prediction of zero-shear viscosity of base bitumen based on the master curve of dynamic shear modulus according to claim 1, characterized in that... In step five, the formulas for the Cross and Carreau models are as follows: In the formula, Viscosity; This is the first Newtonian viscosity, i.e., the zero-shear viscosity; This refers to the viscosity in the second Newtonian zone of the flow curve. , denoted as a characteristic constant of the material.

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