Method for determining the cold diffusion index of asphalt rejuvenators

Abstract

This application relates to a method for determining the room temperature diffusion index of asphalt recycling agents, belonging to the technical field of asphalt material performance testing. The method includes the following steps: performing reproducible penetration tests on the same mixed sample at multiple preset time intervals to obtain penetration values ​​of the mixed sample at multiple preset time intervals, wherein the mixed sample is composed of aged asphalt sample and recycling agent; calculating the diffusion depth and diffusion rate of the recycling agent at the preset time intervals based on the penetration values ​​of the mixed sample at the preset time intervals, and obtaining the diffusion index of the recycling agent based on the diffusion depth and diffusion rate of the recycling agent. This application can obtain the diffusion index of the recycling agent by conducting tests on a single mixed sample multiple times, thereby enabling the analysis of the diffusion capacity of the recycling agent at room temperature based on the diffusion index, and thus providing a favorable basis for performance evaluation of the recycling agent used in asphalt cold recycling operations.

Description

Technical Field

[0001] This application relates to the technical field of asphalt material performance testing, and in particular to a method for determining the room temperature diffusion index of asphalt recycling agents. Background Technology

[0002] As most roads in my country enter the major and medium-scale maintenance phase, the resurfacing of asphalt pavements generates a large amount of waste asphalt mixture. Properly disposing of this mixture can not only achieve significant economic benefits but also conserve substantial resources. The recycled asphalt mixture technology involves remixing old asphalt mixtures with new aggregates and asphalt in a specific ratio and then paving the pavement to meet its performance requirements.

[0003] After long-term use, old asphalt mixtures suffer from severe asphalt aging. Current experience shows that recycled asphalt mixtures formed by mixing old asphalt with new aggregates and asphalt have poor water stability and low-temperature stability. Asphalt recycling agents are needed to modify and restore its properties, enabling the reused asphalt mixture to exhibit excellent pavement performance. Asphalt recycling agents come into contact with aged asphalt and disperse under mechanical mixing, macroscopically appearing uniform. However, in reality, the two remain separated. The recycling agent gradually diffuses into the aged asphalt over time and with environmental changes, eventually forming a uniform and stable blend. Therefore, the permeability of the recycling agent in aged asphalt mixtures is a key indicator for evaluating its quality. The application of asphalt pavement recycling agents generally includes two methods: hot recycling and cold recycling. In hot recycling, both the recycling agent and asphalt are in a fluid state at high temperatures, and there is a certain degree of compatibility after mechanical mixing. In cold recycling, the recycling agent needs to diffuse and become compatible with the aged asphalt within a certain time to achieve the desired recycling effect. The diffusion index of a rejuvenator is a statistical index that shows the change in the diffusion depth of the rejuvenator in aged asphalt over time. The diffusion index of a rejuvenator can directly reflect its performance.

[0004] Despite extensive research conducted by scholars and research institutions both domestically and internationally on recycled asphalt mixture technology, the performance of recycling agents remains controversial, and the success rate of engineering applications of recycled asphalt mixture technology is still lower than that of virgin asphalt mixtures. Good diffusion ability was considered a key functional requirement for recycling agents from the outset. However, in current recycling technologies, a suitable and feasible method for evaluating the diffusion ability of recycling agents has yet to be found. This has led to a degree of uncertainty in the understanding of the interaction between recycling agents and aged asphalt, as well as in the selection of recycling agents, thus affecting the correct design and use of recycled asphalt mixtures. Cold recycling is imperative to replace hot recycling, placing higher demands on the room-temperature diffusion ability of recycling agents and urgently requiring a simple and feasible testing and evaluation method. Summary of the Invention

[0005] To detect the diffusion ability of asphalt rejuvenator in aged asphalt at room temperature, this application provides a method for determining the room temperature diffusion index of asphalt rejuvenator.

[0006] This application provides a method for determining the room-temperature diffusion index of asphalt recycling agents, employing the following technical solution:

[0007] A method for determining the room temperature diffusion index of asphalt recycling agents includes the following steps:

[0008] The mixed sample is subjected to constant temperature treatment, wherein the temperature range of the constant temperature treatment is 5-60℃, and the mixed sample is composed of aged asphalt sample and recycling agent.

[0009] Under multiple preset time periods, the overall mass of the mixed sample and the sample container under multiple preset time periods is weighed, and the mixed sample is subjected to a reproducible penetration test to obtain the penetration value of the mixed sample under multiple preset time periods.

[0010] Based on the penetration value of the mixed sample at the preset time, the diffusion depth and diffusion rate of the regenerator at the preset time are calculated, and the diffusion index of the regenerator is obtained based on the diffusion depth and diffusion rate of the regenerator.

[0011] By adopting the above technical solution, the mixed sample can be subjected to constant temperature treatment during the interval without penetration test. The mixed sample is placed at 5-60℃ to provide the mixed sample with curing conditions that simulate room temperature, thereby restoring the diffusion performance of the recycling agent during use at room temperature. This allows for a more accurate evaluation of the performance of the recycling agent in asphalt cold recycling operations.

[0012] Furthermore, by adopting the above technical solution, the diffusion performance index of the rejuvenator over time can be obtained by performing penetration tests on a single mixed sample multiple times. However, when using multiple mixed samples for lateral comparison tests, it is impossible to guarantee that the mixing ratio of aged asphalt and rejuvenator in each mixed sample is exactly the same, nor that the contact area between the aged asphalt and rejuvenator is exactly the same. This results in variations in the penetration performance of the rejuvenator in the aged asphalt even under the same lateral comparison test conditions, thus affecting the reliability of the data and making it impossible to correctly evaluate the diffusion performance of the rejuvenator. Therefore, the above technical solution can improve the poor reliability of evaluating the diffusion performance of the rejuvenator when using multiple mixed samples for lateral comparison tests.

[0013] Specifically, by conducting reproducible penetration tests on the same mixed sample at multiple preset times, the penetration values ​​of the mixed sample at multiple preset times can be obtained. By using the penetration values ​​of the mixed sample at multiple preset times, the diffusion depth and diffusion rate of the regenerator at the corresponding preset time can be calculated, thereby obtaining the statistical index of the diffusion depth of the regenerator changing with time, i.e., the diffusion index of the regenerator. In turn, the trend of the diffusion depth of the regenerator changing with time can be obtained, and the diffusion performance of the regenerator can be judged.

[0014] Optionally, before performing a reproducible penetration test on the same mixed sample at multiple preset time periods, the following steps are included:

[0015] Add the aged asphalt sample to the sample container, weigh the total mass of the aged asphalt sample and the sample container, and measure the initial penetration value of the aged asphalt sample.

[0016] A quantitative regenerant is added to the sample dish to form a mixed sample, and the total mass of the mixed sample and the sample dish in the initial state is weighed.

[0017] The reproducible penetration test on the same mixed sample at multiple preset time periods includes the following steps:

[0018] Under multiple preset time periods, the overall mass of the mixed sample and the sample container under multiple preset time periods is weighed, and the mixed sample is subjected to a reproducibility penetration test.

[0019] Before calculating the diffusion depth and diffusion rate of the regenerant at the preset time based on the penetration value of the mixed sample at the preset time, the following steps are also included:

[0020] Based on the overall mass of the aged asphalt sample and the sample container, the overall mass of the mixed sample and the sample container in the initial state, and the overall mass of the mixed sample and the sample container at the preset time, the depth of the regenerant in the sample container at the preset time is calculated.

[0021] The calculation of the diffusion depth and diffusion rate of the regenerant at the preset time, based on the penetration value of the mixed sample at the preset time, includes the following steps:

[0022] Based on the penetration value of the mixed sample at the preset time, the depth of the rejuvenator in the sample dish at the preset time, and the initial penetration value of the aged asphalt sample, the diffusion depth of the rejuvenator at the preset time is calculated, and based on the diffusion depth of the rejuvenator at the preset time, the diffusion rate of the rejuvenator at the preset time is calculated.

[0023] By adopting the above technical solution, the volume change of the rejuvenator can be calculated by measuring the overall mass change of the mixed sample, thereby calculating the depth of the rejuvenator in the sample dish at the corresponding time. This reduces the impact of the volume change of the rejuvenator on the test results during the test, further improving the accuracy of the data. At the same time, it avoids peeling the rejuvenator from the surface of the aged asphalt during the penetration test, thus improving the convenience of operation and avoiding the impact of rejuvenator peeling on the accuracy of the measurement data.

[0024] Traditional methods for penetration testing require peeling the rejuvenator from the surface of aged asphalt to measure its penetration value. However, the peeling process cannot guarantee complete removal of the rejuvenator from the aged asphalt and can easily affect the asphalt surface, thus impacting the accuracy of the data. The aforementioned technical solution eliminates this peeling process. The penetration test is performed on a mixture of rejuvenator and aged asphalt. The penetration value of the aged asphalt is obtained by subtracting the depth of the rejuvenator in the sample dish during the final calculation. This solution improves both operational convenience and, to some extent, data accuracy.

[0025] Because most rejuvenating agents are volatile, they are prone to volatilization during testing, leading to volume changes and affecting the accuracy of the data. Furthermore, in each penetration test, the measuring needle comes into contact with the rejuvenating agent, potentially causing loss and volume changes, thus affecting data accuracy. By employing the above technical solution, the overall mass of the aged asphalt sample and its container can be weighed in the initial state, as well as the overall mass of the mixed sample and its container in the initial state. The corresponding preset time can also be measured before each penetration test. The overall mass of the mixed sample and the sample container is used to calculate the depth of the rejuvenator in the sample container at the corresponding preset time, based on the overall mass of the aged asphalt sample and the sample container, the overall mass of the mixed sample and the sample container in the initial state, and the overall mass of the mixed sample and the sample container at the corresponding preset time. Furthermore, by subtracting the depth of the rejuvenator in the sample container at the corresponding preset time and the initial penetration value of the aged asphalt sample from the penetration value of the mixed sample obtained in each penetration test at the preset time, the diffusion depth of the rejuvenator within the corresponding preset time can be calculated, thereby enabling the calculation of the diffusion rate of the rejuvenator at the corresponding preset time.

[0026] Optionally, when n < 7, the interval between two adjacent reproducibility penetration tests is 2-3 days; when n ≥ 7, the interval between two adjacent reproducibility penetration tests is 3-5 days, where n is the corresponding number of test days.

[0027] By adopting the above technical solution, the trend of the diffusion performance of the rejuvenator over time can be reflected more accurately, thus facilitating a more accurate evaluation of the rejuvenator's diffusion capacity. When the rejuvenator comes into contact with aged asphalt, the diffusion rate of the rejuvenator is initially faster, but gradually slows down over time. Therefore, by setting the interval between two adjacent penetration tests to 2-3 days within seven days, the diffusion performance of the rejuvenator within seven days can be better reflected. By setting the interval between two adjacent penetration tests to 3-5 days after seven days, the diffusion performance of the rejuvenator after seven days can be reflected relatively well, thereby improving the efficiency of the test and better reflecting the law of change of the rejuvenator's diffusion performance over time.

[0028] Optionally, the number of reproducibility penetration tests on the mixed sample shall not be less than 5.

[0029] By adopting the above technical solution, the trend of the diffusion performance of the regenerator over time can be reflected more accurately, thus enabling a more accurate evaluation of the diffusion capacity of the regenerator. Extensive practical experiments have shown that at least five experiments are required to better reflect the pattern of the diffusion performance of the regenerator over time.

[0030] Optionally, the diffusion rate of the regenerant is calculated as follows:

[0031] K n = 100%

[0032] D n D represents the diffusion depth of the regenerant at the preset time. m The diffusion depth of the regenerant obtained from the previous test on day n.

[0033] By adopting the above technical solution, the ratio of the diffusion depth of the regenerator on day n to the diffusion depth of the regenerator in the previous test can be calculated, thereby reflecting the diffusion rate (slope) of the regenerator on day n, and providing a basis for evaluating the diffusion performance of the regenerator.

[0034] Optionally, the diffusion depth of the regenerant is calculated as follows:

[0035] D n =D 1dn -D 3dn -D0

[0036] In the formula, D 1dn D represents the penetration value of the mixed sample at the preset time. 3dn D0 represents the depth of the regenerant in the sample dish at the preset time, and D0 represents the initial penetration value of the aged asphalt sample.

[0037] By adopting the above technical solution, the diffusion depth of the regenerator on day n can be calculated, thereby obtaining the law of change of the diffusion depth of the regenerator over time, which further provides a basis for evaluating the diffusion performance of the regenerator; at the same time, it provides data support for calculating the diffusion rate of the regenerator.

[0038] Optionally, the method for calculating the depth of the regenerant in the sample dish at the preset time is as follows:

[0039] D 3dn =

[0040] In the formula, V1 is the initial volume of the regenerant, V 3dn The value represents the volume change of the regenerant after a preset time, and d is the diameter of the sample dish.

[0041] By adopting the above technical solution, the depth of the regenerant in the sample dish on day n can be calculated, thus providing data support for calculating the diffusion depth of the regenerant on day n.

[0042] Optionally, the method for calculating the volume change of the regenerant after a preset time is as follows:

[0043] V 3dn =

[0044] In the formula, m2 is the total mass of the mixed sample and the sample container in the initial state, m dn The total mass of the mixed sample and the sample container at the preset time. The density of the regenerant.

[0045] By adopting the above technical solution, the volume change of the regenerant after n days can be calculated, providing data support for calculating the depth of the regenerant in the sample dish on day n.

[0046] Optionally, the initial volume of the regenerant can be calculated as follows:

[0047] V1=

[0048] In the formula, m3 is the initial mass of the regenerant.

[0049] By adopting the above technical solution, the initial volume of the regenerant can be calculated, thus providing data support for calculating the volume change of the regenerant after n days.

[0050] Optionally, the initial mass of the regenerant is calculated as follows:

[0051] m3 = m2 - m1

[0052] In the formula, m1 is the total mass of the aged asphalt sample and the sample container.

[0053] By adopting the above technical solution, the initial mass of the regenerant can also be calculated, providing data support for calculating the initial volume of the regenerant.

[0054] In summary, this application includes at least one of the following beneficial technical effects:

[0055] 1. By subjecting the mixed sample to constant temperature treatment, it is possible to provide the mixed sample with curing conditions that simulate room temperature, thereby restoring the diffusion performance of the recycling agent during use at room temperature, and thus providing a favorable basis for the performance evaluation of the recycling agent used in asphalt cold recycling operations.

[0056] 2. By conducting penetration tests on a single mixed sample at specific times, the diffusion performance index of the rejuvenator over time can be obtained, providing a favorable basis for evaluating the diffusion performance of the rejuvenator. This improves upon the shortcomings of using multiple mixed samples for lateral comparison tests, where the mixing ratio of rejuvenator and aged asphalt in each mixed sample cannot be guaranteed to be exactly the same, nor can the contact area between aged asphalt and rejuvenator in each mixed sample be guaranteed to be exactly the same. As a result, even when conducting lateral comparison tests under the same conditions, the penetration performance of the rejuvenator in aged asphalt in each mixed sample is still different, which affects the reliability of the test data.

[0057] 3. By measuring the overall mass change of the mixed sample, the volume change of the rejuvenator can be calculated, thereby determining the depth of the rejuvenator in the sample dish at a corresponding time. This allows for the calculation of the rejuvenator's diffusion depth by subtracting the depth data at the corresponding time, thus avoiding the influence of the rejuvenator's volume change on the test results and improving the accuracy of the test data. Simultaneously, it avoids the need to peel the rejuvenator from the surface of aged asphalt during penetration testing, improving operational convenience and preventing the potential impact of rejuvenator peeling on the accuracy of the measurement data.

[0058] 4. By specifying the number of penetration tests and the interval between two adjacent penetration tests, the trend of the diffusion performance of the regenerator over time can be reflected more accurately, thus facilitating a more accurate evaluation of the regenerator's diffusion capacity. Attached Figure Description

[0059] Figure 1 This is a flowchart illustrating a method for determining the room temperature diffusion index of asphalt recycling agents provided in this application.

[0060] Figure 2 This is a diffusion index diagram of regenerant 1 provided in Example 1 of this application;

[0061] Figure 3 This is a diffusion rate diagram of regenerant 1 provided in Example 1 of this application;

[0062] Figure 4 This is a diffusion index diagram of regenerant 2 provided in Example 2 of this application;

[0063] Figure 5 This is a diffusion rate diagram of regenerant 2 provided in Example 2 of this application;

[0064] Figure 6 This is a diffusion index diagram of the regenerant 3 provided in Example 3 of this application;

[0065] Figure 7 This is a diffusion rate diagram of the regenerant 3 provided in Example 3 of this application;

[0066] Figure 8 This is a comparison chart of the diffusion indices of regenerator 1, regenerator 2, and regenerator 3 provided in the embodiments of this application;

[0067] Figure 9 This is a comparison diagram of the diffusion rates of regenerator 1, regenerator 2, and regenerator 3 provided in the embodiments of this application. Detailed Implementation

[0068] The following is in conjunction with the appendix Figure 1-2 This application will be described in further detail.

[0069] This application discloses a method for determining the room temperature diffusion index of asphalt recycling agents, the principle of which is as follows:

[0070] An aged asphalt sample is added to a sample dish to provide a simulated asphalt surface. Then, a quantitative amount of rejuvenating agent is added to uniformly cover the surface of the aged asphalt sample, thereby simulating the interaction interface between the rejuvenating agent and the aged asphalt. Under certain test conditions, the rejuvenating agent will continuously diffuse into the interior of the aged asphalt over time. The greater the speed and content of the rejuvenating agent's diffusion into the interior of the aged asphalt, the stronger its diffusion ability. This is reflected in the test index as a faster change in the penetration obtained in the test over time.

[0071] Reference Figure 1 A method for determining the room temperature diffusion index of asphalt recycling agents includes the following steps:

[0072] S1. Preparation: Prepare a certain amount of aged asphalt sample and a certain amount of recycling agent, and mix the recycling agent and aged asphalt sample in a sample dish.

[0073] S101. Preparation of aged asphalt: Recover aged asphalt from recycled asphalt mixture (RAP) according to the method of T0726 or T0727 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20), and prepare aged asphalt samples according to the method of T0602 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20). Add the aged asphalt sample to the sample container. After the aged asphalt has cooled, cover the top of the sample container with the lid. Weigh the total mass of the aged asphalt sample and the sample container and record it as m1 (g, accurate to four decimal places).

[0074] The sample container should be made of metal or hard glass, with a flat bottom and cylindrical shape, an inner diameter of 55mm ± 1mm, and a depth of 35mm ± 1mm. Alternatively, a clean sample container for penetration testing can be used. Before adding the aged asphalt sample, the inner diameter of the sample container must be measured and recorded as d (cm, accurate to four decimal places). The lid of the sample container is used to reduce the influence of the volatilization of the recycling agent on the test. When weighing the aged asphalt sample and the sample container together, an analytical balance with a sensitivity of no more than 0.1mg should be used to ensure the weighing accuracy.

[0075] S102 Initial penetration measurement: After weighing the total mass of the aged asphalt sample and the sample container, measure the initial penetration value of the sample container containing only the aged asphalt, and record it as D0 (mm, accurate to two decimal places).

[0076] S103. Preparation of Rejuvenating Agent: Weigh the required amount of rejuvenating agent (3-5g) and record the initial mass of the rejuvenating agent as m3 (g, accurate to four decimal places). Add the prepared amount of rejuvenating agent into the sample dish and cover the sample dish. Weigh the total mass of the aged asphalt sample, sample dish and rejuvenating agent in the initial state and record it as m2 (g, accurate to four decimal places).

[0077] When weighing the total mass of the aged asphalt sample, rejuvenator, and sample container, an analytical balance with a sensitivity of no more than 0.1 mg should be used to ensure weighing accuracy.

[0078] S2. Insulation work: Place the sample dish containing the mixed sample of aged asphalt and recycling agent in a constant temperature and humidity chamber at 15-25℃ for curing. After a preset specific time, remove the sample dish containing the mixed sample of aged asphalt and recycling agent from the constant temperature and humidity chamber at 15-25℃ for penetration test. After the test, put the sample dish containing the mixed sample of aged asphalt and recycling agent back into the constant temperature and humidity chamber at 15-25℃.

[0079] S3. Test Procedure: Conduct multiple reproducible penetration tests on the mixed samples containing aged asphalt and recycling agent at multiple preset time periods, and measure the penetration value at the corresponding time. When the preset time is less than seven days, the interval between two adjacent preset time periods is 2-3 days. When the preset time is greater than or equal to seven days, the interval between two adjacent preset time periods is 3-5 days. The number of penetration tests should not be less than 5.

[0080] In this embodiment, penetration tests were conducted on the mixed samples containing aged asphalt and recycling agent on the first day, the third day, the fifth day, the seventh day, the tenth day, the thirteenth day, the sixteenth day, the twenty-first day, the twenty-sixth day, and the thirty-first day, respectively.

[0081] S301. Pre-test weighing: After removing the sample dish containing the mixed sample of aged asphalt and recycling agent from the constant temperature and humidity chamber, first weigh the total mass of the aged asphalt, recycling agent, and sample dish, and record it as m. dn (g, accurate to four decimal places, n is the corresponding number of days).

[0082] When weighing the total mass of the aged asphalt sample, rejuvenator, and sample container, an analytical balance with a sensitivity of no more than 0.1 mg should be used to ensure weighing accuracy.

[0083] S302. Penetration Test: After weighing the aged asphalt sample, rejuvenator, and sample container on day n, open the sample container lid and place the sample container containing the mixed sample of aged asphalt and rejuvenator on the platform of the fully automatic penetration tester. Start the instrument to measure the penetration value of the mixed sample of aged asphalt and rejuvenator, and record it as D. 1dn (mm, accurate to two decimal places, n is the corresponding number of days).

[0084] When measuring penetration, at least three parallel tests should be conducted for the corresponding number of days. The distance between each test point and the edge of the sample dish should be no less than 10 mm. During the test, the loss of aged asphalt and recycling agent samples should be minimized. When the penetration test result is less than 50 (0.1 mm), the allowable error for repeatability test is 2 (0.1 mm), and the allowable error for reproducibility test is 4 (0.1 mm). When the penetration test result is greater than or equal to 50 (0.1 mm), the allowable error for repeatability test is 4% of the average value, and the allowable error for reproducibility test is 8% of the average value.

[0085] S303. Reset after test: After measuring the penetration of the mixed sample of aged asphalt and recycling agent for the corresponding number of days, place the sample container containing the mixed sample of aged asphalt and recycling agent back into the constant temperature and humidity chamber at the corresponding temperature, and continue the test according to the above steps after the corresponding number of days.

[0086] S4. Calculation work: Calculate the diffusion depth D of the regenerant based on the results of the penetration test. n (mm, accurate to two decimal places, n is the corresponding number of days) and diffusivity K n (%, where n is the corresponding number of days).

[0087] S401. Calculate the diffusion depth D of the regenerant. n (mm, accurate to two decimal places, n is the corresponding number of days):

[0088] The first step is to calculate the initial volume V1 (cm³) of the regenerant. 3 The calculation method for V1 is: V1 = In the formula, m3 (g) is the initial mass of the regenerant. (g / cm) 3 ( ) represents the density of the regenerant at the test temperature;

[0089] The second step is to calculate the volume change of the regenerant over the corresponding number of days, denoted as V. 3dn (cm) 3 ), V 3dn The calculation method is as follows: V 3dn = (In the formula, n is the corresponding number of days, (g / cm) 3 (m) represents the density of the regenerant at the test temperature. dn (g) represents the total mass of the aged asphalt, recycling agent, and sample container on day n, and m2(g) represents the total mass of the aged asphalt, recycling agent, and sample container in the initial state.

[0090] The third step is to calculate the depth of the regenerant in the sample dish for the corresponding number of days, denoted as D. 3dn (mm), D 3dn The calculation method is as follows: D 3dn = 10 (where n is the corresponding number of days, V1 (cm) 3 V represents the initial volume of the regenerant. 3dn (cm) 3 (where d is the volume change of the regenerant on day n, and d (mm) is the diameter of the sample dish).

[0091] The fourth step is to calculate the diffusion depth D of the regenerant. n (mm),D n The calculation method is D n =D 1dn -D 3dn -D0 (where D is the formula) 1dn (mm) represents the penetration value of the mixed sample of asphalt and recycling agent aged on day n, D 3dn(mm) represents the depth of the regenerant in the sample dish on day n, and D0 (mm) represents the initial penetration value of the sample dish containing only aged asphalt.

[0092] S402, Calculate the diffusion rate K of the regenerator. n (%, where n is the corresponding number of days), K n The calculation method for K is as follows: n = 100% (where n is the corresponding number of days, D) n (mm) represents the diffusion index of the regenerant on day n, D m (mm) represents the diffusion index of the regenerant obtained from the penetration test on day n prior.

[0093] S5. Based on the diffusion depth data of the regenerator, plot a line graph showing the change of the diffusion depth of the regenerator over time, i.e., the diffusion index of the regenerator. Evaluate the diffusion performance of the regenerator based on the diffusion index and the diffusion rate of the regenerator.

[0094] To better verify the method for determining the room temperature diffusion index of asphalt recycling agents provided in this application, the following are some representative embodiments of this application:

[0095] Example 1: Determination of the diffusion index of regenerant 1.

[0096] S1. Prepare a certain amount of aged asphalt sample and a certain amount of recycling agent 1, and mix the recycling agent 1 and aged asphalt sample in a sample container.

[0097] S101. Recover aged asphalt from recycled asphalt mixture (RAP) according to the method of T0726 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20), and prepare aged asphalt samples according to the method of T0602 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20). Add the aged asphalt sample to the sample container. After the aged asphalt cools down, cover the top of the sample container with the lid. Weigh the total mass of the aged asphalt sample and the sample container, m1 = 62.2017 g, and measure the diameter of the sample container, d = 5.4400 cm.

[0098] S102. Measure the initial penetration value D0 = 4.21 mm of the sample dish containing only aged asphalt;

[0099] S103. Weigh the required amount of regenerant 1 and record the initial mass of regenerant 1 as m3 = 3.9828 g. Add the prepared amount of regenerant 1 into the sample dish and cover the sample dish. Weigh the total mass of the aged asphalt sample, the sample dish and regenerant 1 in the initial state as m2 = 66.1845 g.

[0100] S2. Place the sample dish containing the mixed sample of aged asphalt and recycling agent 1 in a 20℃ constant temperature and humidity chamber for curing.

[0101] S3. On the first day, third day, fifth day, seventh day, tenth day, thirteenth day, sixteenth day, twenty-first day, twenty-sixth day and thirty-first day, the sample dish containing the mixed sample of aged asphalt and recycling agent 1 was taken out of the 20℃ constant temperature and humidity chamber for penetration test.

[0102] S301. After removing the sample dish containing the mixed sample of aged asphalt and recycling agent 1 from the constant temperature and humidity chamber, first weigh the total mass of the aged asphalt, recycling agent 1, and sample dish. The data m of the total mass of the aged asphalt, recycling agent 1, and sample dish corresponding to the number of test days is obtained. d1 m d3 m d5 m d7 m d10 m d13 m d16 m d21 m d26 m d31 ;

[0103] S302. Open the sample dish lid, place the sample dish containing the mixed sample of aged asphalt and recycling agent 1 on the platform of the fully automatic penetration meter, start the instrument to measure the penetration value of the mixed sample of aged asphalt and recycling agent 1. The data of the penetration values ​​of the mixed sample of aged asphalt and recycling agent 1 for the corresponding test days are as follows: D 1d1 D 1d3 D 1d5 D 1d7 D 1d10 D 1d13 D 1d16 D 1d21 D 1d26 D 1d31 .

[0104] S4. Calculate the diffusion depth D n and diffusion rate K n

[0105] S401, Calculate the diffusion depth D n :

[0106] The first step is to calculate the initial volume V1 of regenerant 1. = =4.2057cm 3 ;

[0107] The second step is to calculate the volume change of regenerant 1 on day n:

[0108] V3d1 V 3d3 V 3d5 V 3d7 V 3d10 V 3d13 V 3d16 V 3d21 V 3d26 V 3d31 .

[0109] The third step is to calculate the depth of regenerant 1 in the sample dish on day n:

[0110] D 3d1 D 3d3 D 3d5 D 3d7 D 3d10 D 3d13 D 3d16 D 3d21 D 3d26 D 3d31 .

[0111] Step 4: Calculate the diffusion depth D of regenerant 1. n :

[0112] D1=D 1d1 -D 3d1 -D0=0.48 mm;

[0113] D3=D 1d3 -D 3d3 -D0=1.02 mm;

[0114] D5=D 1d5 -D 3d5 -D0=1.52 mm;

[0115] D7=D 1d7 -D 3d7 -D0=1.87 mm;

[0116] D 10 =D 1d10 -D 3d10 -D0=2.19 mm;

[0117] D 13 =D 1d13 -D 3d13 -D0=2.39 mm;

[0118] D 16 =D 1d16 -D 3d16 -D0=2.55 mm;

[0119] D 21 =D1d21 -D 3d21 -D0=2.68 mm;

[0120] D 26 =D 1d26 -D 3d26 -D0=2.80 mm;

[0121] D 31 =D 1d31 -D 3d31 -D0=2.91 mm.

[0122] S402. Calculate the diffusion rate K of regenerant 1 on day n. n :

[0123] K3= 100% = 100% = 212.50%;

[0124] K5= 100% = 100% = 149.01%;

[0125] K7= 100% = 100% = 123.02%;

[0126] K 10 = 100% = 100% = 117.11%;

[0127] K 13 = 100% = 100% = 109.13%;

[0128] K 16 = 100% = 100% = 106.69%;

[0129] K 21 = 100% = 100% = 105.09%;

[0130] K 26 = 100% = 100% = 104.47%;

[0131] K 31 = 100% = 100% = 103.92%.

[0132] S5. Based on the diffusion depth data of regenerator 1, plot a line graph showing the change in diffusion depth of regenerator 1 over time, i.e., the diffusion index of regenerator 1, as shown below. Figure 2 As shown, a line graph depicting the change in the diffusion rate of regenerator 1 over time is plotted based on the diffusion rate of regenerator 1. Figure 3 As shown, the diffusion performance of regenerator 1 is evaluated based on its diffusion index and diffusion rate.

[0133] Example 2: Determination of the diffusion index of regenerant 2.

[0134] S1. Prepare a certain amount of aged asphalt sample and a certain amount of recycling agent 2, and mix the recycling agent 2 and aged asphalt sample in a sample container.

[0135] S101. Recover aged asphalt from recycled asphalt mixture (RAP) according to the method of T0726 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20), and prepare aged asphalt samples according to the method of T0602 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20). Add the aged asphalt sample to the sample container. After the aged asphalt cools down, cover the top of the sample container with the sample container lid. Weigh the total mass of the aged asphalt sample and the sample container, m1 = 63.7435 g, and measure the diameter of the sample container, d = 5.4400 cm.

[0136] S102. Measure the initial penetration value D0 = 4.21 mm of the sample dish containing only aged asphalt;

[0137] S103. Weigh the required amount of rejuvenating agent 2 and record the initial mass of rejuvenating agent 2 as m3 = 4.0091 g. Add the prepared amount of rejuvenating agent 2 into the sample dish and cover the sample dish. Weigh the total mass of the aged asphalt sample, the sample dish and rejuvenating agent 2 in the initial state as m2 = 67.7526 g.

[0138] S2. Place the sample dish containing the mixed sample of aged asphalt and recycling agent 2 in a constant temperature and humidity chamber at 20℃ for curing.

[0139] S3. On the first day, third day, fifth day, seventh day, tenth day, thirteenth day, sixteenth day, twenty-first day, twenty-sixth day and thirty-first day, the sample dish containing the mixed sample of aged asphalt and recycling agent 2 was taken out of the 20℃ constant temperature and humidity chamber for penetration test.

[0140] S301. After removing the sample dish containing the mixed sample of aged asphalt and recycling agent 2 from the constant temperature and humidity chamber, first weigh the total mass of the aged asphalt, recycling agent 2, and sample dish. The data for the total mass of the aged asphalt, recycling agent 2, and sample dish at the corresponding number of days are as follows: m d1 md3 m d5 m d7 m d10 m d13 m d16 m d21 m d26 m d31 ;

[0141] S302. Open the sample dish lid, place the sample dish containing the mixed sample of aged asphalt and recycling agent 2 on the platform of the fully automatic penetration meter, start the instrument to measure the penetration value of the mixed sample of aged asphalt and recycling agent 2. The penetration values ​​of the mixed sample of aged asphalt and recycling agent 2 for the corresponding number of days are as follows: D 1d1 D 1d3 D 1d5 D 1d7 D 1d10 D 1d13 D 1d16 D 1d21 D 1d26 D 1d31 .

[0142] S4. Calculate the diffusion depth D n and diffusion rate K n

[0143] S401, Calculate the diffusion depth D n :

[0144] The first step is to calculate the initial volume V1 of regenerant 2. =4.3295cm 3 ;

[0145] The second step is to calculate the volume change of regenerant 2 on day n:

[0146] V 3d1 V 3d3 V 3d5 V 3d7 V 3d10 V 3d13 V 3d16 V 3d21 V 3d26 V 3d31 .

[0147] The third step is to calculate the depth of regenerant 2 in the sample dish on day n:

[0148] D 3d1 D 3d3 D 3d5 D 3d7 D 3d10 D 3d13 D3d16 D 3d21 D 3d26 D 3d31 .

[0149] Step 4: Calculate the diffusion depth D n :

[0150] D1=D 1d1 -D 3d1 -D0=0.39 mm;

[0151] D3=D 1d3 -D 3d3 -D0=1.06 mm;

[0152] D5=D 1d5 -D 3d5 -D0=1.41 mm;

[0153] D7=D 1d7 -D 3d7 -D0=1.72 mm;

[0154] D 10 =D 1d10 -D 3d10 -D0=2.00 mm;

[0155] D 13 =D 1d13 -D 3d13 -D0=2.18 mm;

[0156] D 16 =D 1d16 -D 3d16 -D0=2.30 mm;

[0157] D 21 =D 1d21 -D 3d21 -D0=2.41 mm;

[0158] D 26 =D 1d26 -D 3d26 -D0=2.50 mm;

[0159] D 31 =D 1d31 -D 3d31 -D0=2.59 mm.

[0160] S402. Calculate the diffusion rate K on day n. n :

[0161]

[0162]

[0163] S5. Based on the diffusion depth data of regenerator 2, plot a line graph showing the change in diffusion depth of regenerator 2 over time, i.e., the diffusion index of regenerator 2, as shown below. Figure 4 As shown, a line graph depicting the diffusion rate of regenerator 2 over time is plotted based on the diffusion rate of regenerator 2. Figure 5 As shown, the diffusion performance of regenerator 2 is evaluated based on its diffusion index and diffusion rate.

[0164] Example 3: Determination of the diffusion index of regenerant 3.

[0165] S1. Prepare a certain amount of aged asphalt sample and a certain amount of recycling agent 3, and mix the recycling agent 3 and aged asphalt sample in a sample container.

[0166] S101. Recover aged asphalt from recycled asphalt mixture (RAP) according to the method of T0726 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20), and prepare aged asphalt samples according to the method of T0602 in the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTGE20). Add the aged asphalt sample to the sample container. After the aged asphalt cools down, cover the top of the sample container with the sample container lid. Weigh the total mass of the aged asphalt sample and the sample container, m1 = 61.8483 g, and measure the diameter of the sample container, d = 5.4400 cm.

[0167] S102. Measure the initial penetration value D0 = 4.21 mm of the sample dish containing only aged asphalt;

[0168] S103. Weigh the required amount of regenerant 3 and record the initial mass of regenerant 3 as m3 = 4.0162 g. Add the prepared amount of regenerant 3 into the sample dish and cover the sample dish. Weigh the total mass of the aged asphalt sample, the sample dish and the regenerant 3 in the initial state as m2 = 65.8645 g.

[0169] S2. Place the sample dish containing the mixed sample of aged asphalt and recycling agent 3 in a 20℃ constant temperature and humidity chamber for curing.

[0170] S3. On the first day, third day, fifth day, seventh day, tenth day, thirteenth day, sixteenth day, twenty-first day, twenty-sixth day and thirty-first day, the sample dish containing the mixed sample of aged asphalt and recycling agent 3 was taken out of the 20℃ constant temperature and humidity chamber for penetration test.

[0171] S301. After removing the sample dish containing the mixed sample of aged asphalt and recycling agent 3 from the constant temperature and humidity chamber, first weigh the total mass of the aged asphalt, recycling agent 3, and sample dish. The data for the total mass of the aged asphalt, recycling agent 3, and sample dish at the corresponding number of days are as follows: m d1 m d3 m d5 m d7 m d10 m d13 m d16 m d21 m d26 m d31 ;

[0172] S302. Open the sample dish lid, place the sample dish containing the mixed sample of aged asphalt and recycling agent 3 on the platform of the fully automatic penetration meter, start the instrument to measure the penetration value of the mixed sample of aged asphalt and recycling agent 3. The penetration values ​​of the mixed sample of aged asphalt and recycling agent 3 for the corresponding number of days are as follows: D 1d1 D 1d3 D 1d5 D 1d7 D 1d10 D 1d13 D 1d16 D 1d21 D 1d26 D 1d31 .

[0173] S4. Calculate the diffusion depth D n and diffusion rate K n

[0174] S401, Calculate the diffusion depth D n :

[0175] The first step is to calculate the initial volume V1 of regenerant 3. =4.4378cm 3 ;

[0176] The second step is to calculate the volume change of regenerant 3 on day n:

[0177] V 3d1 V 3d3 V 3d5 V 3d7 V 3d10 V 3d13 V 3d16 V 3d21 V 3d26 V 3d31 .

[0178] The third step is to calculate the depth of regenerant 3 in the sample dish on day n:

[0179] D 3d1 、D 3d3 、D 3d5 、D 3d7 、D 3d10 、D 3d13 、D 3d16 、D 3d21 、D 3d26 、D 3d31 。

[0180] Step 4: Calculate the diffusion depth D n :

[0181] D1 = D 1d1 - D 3d1 - D0 = 0.52 mm;

[0182] D3 = D 1d3 - D 3d3 - D0 = 1.17 mm;

[0183] D5 = D 1d5 - D 3d5 - D0 = 1.80 mm;

[0184] D7 = D 1d7 - D 3d7 - D0 = 2.13 mm;

[0185] D 10 = D 1d10 - D 3d10 - D0 = 2.37 mm;

[0186] D 13 = D 1d13 - D 3d13 - D0 = 2.48 mm;

[0187] D 16 = D 1d16 - D 3d16 - D0 = 2.58 mm;

[0188] D 21 = D 1d21 - D 3d21 - D0 = 2.69 mm;

[0189] D 26 = D 1d26 - D 3d26 - D0 = 2.77 mm;

[0190] D 31 = D 1d31 - D 3d31 - D0 = 2.84 mm.

[0191] S402. Calculate the diffusion rate K on day n. n :

[0192]

[0193] S5. Based on the diffusion depth data of regenerator 3, plot a line graph showing the change in diffusion depth of regenerator 3 over time, i.e., the diffusion index of regenerator 3, as shown below. Figure 6 As shown, a line graph depicting the diffusion rate of regenerator 3 over time is plotted based on the diffusion rate of regenerator 3. Figure 7 As shown, the diffusion performance of regenerator 3 is evaluated based on its diffusion index and diffusion rate.

[0194] In summary, the diffusion indices of regenerator 1, regenerator 2, and regenerator 3 are compared to... Figure 8 As shown, the diffusion rates of regenerator 1, regenerator 2, and regenerator 3 are compared to, for example... Figure 9 As shown. By Figure 8 and Figure 9 It can be seen that regenerator 3 exhibits better diffusion depth and faster diffusion rate in the early stages, indicating that its initial diffusion effect is relatively better. After 10 days, the diffusion depth and diffusion rate of regenerator 1 and regenerator 2 gradually catch up with and surpass that of regenerator 3, thus concluding that regenerator 1 and regenerator 2 have relatively better long-term diffusion effects. Therefore, the diffusion performance of regenerator 1, regenerator 2, and regenerator 3 can be comprehensively compared and judged using this detection method as follows:

[0195] Recycling agent 3 mainly softens aged asphalt materials. In addition to the initial surface softening effect, recycling agents 1 and 2 can also diffuse and become compatible in asphalt over a long period of time, achieving better recycling results.

[0196] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A method for determining the room temperature diffusion index of asphalt recycling agents, characterized in that, Includes the following steps: The mixed sample is subjected to constant temperature treatment, wherein the temperature range of constant temperature treatment is 5-60℃, and the mixed sample is composed of aged asphalt sample and recycling agent. Under multiple preset time periods, the overall mass of the mixed sample and the sample container under multiple preset time periods is weighed, and the mixed sample is subjected to a reproducible penetration test to obtain the penetration value of the mixed sample under multiple preset time periods. Based on the penetration value of the mixed sample at the preset time, the diffusion depth and diffusion rate of the regenerator at the preset time are calculated, and the diffusion index of the regenerator is obtained based on the diffusion depth and diffusion rate of the regenerator. Before performing a reproducible penetration test on the same mixed sample at multiple preset time periods, the following steps are included: Add the aged asphalt sample to the sample container, weigh the total mass of the aged asphalt sample and the sample container, and measure the initial penetration value of the aged asphalt sample. A measured amount of regenerant is added to the sample dish to form a mixed sample, and the total mass of the mixed sample and the sample dish in the initial state is weighed. The reproducible penetration test on the same mixed sample at multiple preset time periods includes the following steps: Under multiple preset time periods, the overall mass of the mixed sample and the sample container under multiple preset time periods is weighed, and the mixed sample is subjected to a reproducibility penetration test. Before calculating the diffusion depth and diffusion rate of the regenerant at the preset time based on the penetration value of the mixed sample at the preset time, the following steps are also included: Based on the overall mass of the aged asphalt sample and the sample container, the overall mass of the mixed sample and the sample container in the initial state, and the overall mass of the mixed sample and the sample container at the preset time, the depth of the regenerant in the sample container at the preset time is calculated. The calculation of the diffusion depth and diffusion rate of the regenerant at the preset time, based on the penetration value of the mixed sample at the preset time, includes the following steps: Based on the penetration value of the mixed sample at the preset time, the depth of the regenerator in the sample dish at the preset time, and the initial penetration value of the aged asphalt sample, the diffusion depth of the regenerator at the preset time is calculated, and based on the diffusion depth of the regenerator at the preset time, the diffusion rate of the regenerator at the preset time is calculated. When n < 7, the interval between two adjacent reproducibility penetration tests is 2-3 days; when n ≥ 7, the interval between two adjacent reproducibility penetration tests is 3-5 days, where n is the corresponding number of test days.

2. The method for determining the room temperature diffusion index of asphalt recycling agents according to claim 1, characterized in that, The number of reproducibility penetration tests on the mixed sample shall not be less than 5.

3. The method for determining the room temperature diffusion index of asphalt recycling agents according to claim 2, characterized in that, The method for calculating the diffusion rate of the regenerant is as follows: K n = 100％ In the formula, D n D represents the diffusion depth of the regenerant at the preset time. m The diffusion depth of the regenerant obtained from the previous test on day n.

4. The method for determining the room temperature diffusion index of asphalt recycling agents according to claim 3, characterized in that, The method for calculating the diffusion depth of the regenerant is as follows: D n =D 1dn -D 3dn -D0 In the formula, D 1dn D represents the penetration value of the mixed sample at the preset time. 3dn D0 represents the depth of the regenerant in the sample dish at the preset time, and D0 represents the initial penetration value of the aged asphalt sample.

5. The method for determining the room temperature diffusion index of asphalt recycling agents according to claim 4, characterized in that, The method for calculating the depth of the regenerant in the sample dish at the preset time is as follows: D 3dn = In the formula, V1 is the initial volume of the regenerant, V 3dn The value represents the volume change of the regenerant after a preset time, and d is the diameter of the sample dish.

6. The method for determining the room temperature diffusion index of asphalt recycling agents according to claim 5, characterized in that, The method for calculating the volume change of the regenerant after a preset time is as follows: V 3dn = In the formula, m2 is the total mass of the mixed sample and the sample container in the initial state, m dn The total mass of the mixed sample and the sample container at the preset time. The density of the regenerant.

7. The method for determining the room temperature diffusion index of asphalt recycling agents according to claim 6, characterized in that, The initial volume of the regenerant is calculated as follows: V1= In the formula, m3 is the initial mass of the regenerant.

8. A method for determining the room temperature diffusion index of asphalt recycling agents according to claim 7, characterized in that, The method for calculating the initial mass of the regenerant is as follows: m3 = m2 - m1 In the formula, m1 is the total mass of the aged asphalt sample and the sample container.

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