A regeneration agent permeability evaluation method and index based on a contact angle test

Abstract

A regeneration agent permeability evaluation method and index based on a contact angle test, steps as follows: take 0.5 mL of aged asphalt heated to a flow state and add to a contact angle device, place the sample at a set temperature for 30 min, then add 5% of a high-permeability warm regeneration agent, place the sample in the device at a set temperature for 1 h of permeation, and finally perform a contact angle test, take the contact angle data at 10, 20, 30, 40, and 50 drops to evaluate the permeation effect of the regeneration agent, and calculate the contact angle between the asphalt and the glass slide, the contact angle test temperature is the set temperature, the total measurement time of the contact angle data is 1 min, the contact angle is measured once every 1 s, a total of 60 contact angle data are measured for each group, the data are fitted by a power function y=ax b b represents the paving rate of the asphalt on the aggregate surface, the greater the absolute value of b, the faster the paving rate, and the better the permeability of the regeneration agent. The method has the advantages of small sample size, simple operation, accurate test, etc.

Description

Technical Field

[0001] This invention relates to the fields of road engineering materials technology and maintenance technology, specifically to a method and index for evaluating the permeability of regenerators based on contact angle tests. Background Technology

[0002] Currently, the utilization rate of solid waste remains low, consuming a large amount of land resources and posing significant ecological and environmental safety risks. The comprehensive utilization level of bulk solid waste urgently needs to be further improved, shifting from "inefficient, low-value, and decentralized utilization" to "efficient, high-value, and large-scale utilization."

[0003] Asphalt pavement recycling technology has been widely used in road engineering, playing a crucial role, particularly in pavement performance repair and the comprehensive utilization of large-scale solid waste. To transform asphalt pavement recycling technology from "inefficient, low-value, and decentralized utilization" to "efficient, high-value, and large-scale utilization," it is necessary to improve the recycling efficiency. In high-efficiency asphalt mixture recycling technology, a key issue is the diffusion of the rejuvenating agent during the recycling process, as the degree of diffusion directly affects the recycling effect of the mixture. Current research on the diffusion of rejuvenating agents in rejuvenating agents often focuses on molecular dynamics simulations, stratified extraction, and improved simple performance tests (such as penetration and softening point). Molecular dynamics studies the penetration effect of rejuvenating agents in the microscopic realm, but a reliable connection with macroscopic experiments has not yet been established. Stratified extraction tests can simulate the diffusion mechanism between the old asphalt film and the rejuvenating agent, but they are difficult to operate, and the results are affected by the disturbances caused by trichloroethylene and mineral powder. Simple macroscopic experiments are insufficient to characterize the degree of diffusion. Therefore, it is essential to design a diffusion test that can both macroscopically evaluate the penetration effect of the rejuvenating agent and is easy to operate and yields reliable results. Summary of the Invention

[0004] Technical problem solved: In view of the problem that the existing methods for evaluating the permeability of regenerators based on contact angle tests cannot intuitively and efficiently reflect the permeability of regenerators, this invention proposes a permeability evaluation method and index based on contact angle tests, which has the advantages of small sample size, simple operation and accurate test.

[0005] Technical solution: A method for evaluating the permeability of regenerants based on contact angle testing, comprising the following steps:

[0006] Step 1. Heat the aged asphalt to a fluid state, draw 0.5 mL with a glass syringe, add it to the contact angle test sample tube, place it in the sample tube rack in the oven, select the temperature to be evaluated for permeability, i.e., set the temperature and keep it warm for 30 min, then add 5 wt% of recycling agent to obtain the sample, place the sample in the high-level heat preservation equipment in the contact angle tester and keep it warm and permeate for 1 h at the set temperature.

[0007] Step 2. Then, conduct the contact angle test. While the asphalt is being insulated, place the glass slide in the insulated chamber of the contact angle analyzer. Adjust the instrument so that the asphalt slowly drips onto the surface of the glass slide. To prevent air bubbles from forming in the initial droplets, wipe away the first two droplets pushed out by the instrument. Start recording from the third drop and record a total of 50 drops. Take the contact angle data at the 10th, 20th, 30th, 40th, and 50th drops to evaluate the penetration effect of the recycling agent. Calculate the contact angle between the asphalt and the glass slide. The test temperature is the set temperature. The total measurement time for the contact angle data is 1 minute. Measure the contact angle once every 1 second. Measure a total of 60 contact angle data for each group.

[0008] Step 3. Plot a scatter plot of the contact angle versus time based on the obtained data, and apply the power function y = ax b The fitting analysis showed that, at the set temperature, the contact angle-time variation exhibited a power function relationship, with a fitting coefficient R0. 2 All are greater than 0.97, indicating good correlation for the power function y = ax b The variation characteristics of the contact angle of asphalt on the aggregate surface are determined by a and b. Here, a represents the contact angle when the asphalt just comes into contact with the aggregate at 1 second, which can be regarded as the initial state of the contact angle; b represents the paving rate of asphalt on the aggregate surface. Power function fitting is performed on the contact angle-time scatter plots of 50 sequentially dripping droplets.

[0009] Step 4. Use the b-value to evaluate the penetration of the recycling agent. The larger the absolute value of b, the faster the paving rate, which indicates that the recycling agent has a better penetration effect (the softer the asphalt, the more recycling agent penetrates).

[0010] Preferably, the contact angle testing instrument is the DSA-100 optical contact angle analyzer from Kruss GmbH, Germany, which includes a room temperature device and a high temperature device. It mainly consists of a camera, lighting equipment, and dedicated analysis software, and the contact angle measurement accuracy is 0.01°.

[0011] Preferably, in step one, the aged asphalt is aged using RTFOT aging equipment for a delayed aging time of 720 minutes to simulate the road surface aging asphalt with an actual service life of 15 years.

[0012] The above method is used to evaluate the index of recycling agent permeability, and the index is the asphalt paving rate b on the aggregate surface.

[0013] Furthermore, the larger the absolute value of b, the faster the paving rate, indicating a better penetration effect of the regenerator.

[0014] Beneficial effects: The contact angle test of this invention uses a small amount of sample, is less affected by gravity, and the amount of asphalt pushed out is precisely controlled by machinery. During the asphalt paving process, high-precision cameras and software are used to track and collect data. The test is simple and the data is accurate. Therefore, the contact angle test is an efficient and accurate method for evaluating the permeability of recycling agents. Attached Figure Description

[0015] Figure 1 This is a flowchart of the evaluation method of the present invention.

[0016] Figure 2 This is a schematic diagram of the contact angle test in this invention.

[0017] Figure 3 This shows the variation of the contact angle with the experiment in this invention. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0019] In the examples provided in this specification, the aged asphalt was aged using RTFOT aging equipment for a delayed aging time of 720 minutes to simulate asphalt aging on a road surface with an actual service life of 15 years. A high-penetration, temperature-controlled recycling agent was used to compare with ordinary recycling agents to verify the rationality of its evaluation of penetration effect. The contact angle testing instrument was a DSA-100 optical contact angle analyzer from Kruss GmbH, Germany.

[0020] Example 1

[0021] A method for evaluating the permeability of regenerators based on contact angle tests, wherein the regenerators include a common regenerator and a high-permeability temperature regenerator used as controls, and the technical indicators of the two regenerators are shown in Tables 1 and 2.

[0022] Table 1 Technical Specifications of Common Regenerants

[0023]

[0024] Table 2 Technical Specifications of High-Permeability Temperature Regenerator

[0025]

[0026] like Figure 1 As shown, the temperature in this embodiment is set at 140℃, and the experiment includes the following steps (the following steps are used for ordinary regenerant and high-penetration temperature regenerant respectively):

[0027] (1) Heat the aged asphalt to a fluid state, use a glass syringe to draw 0.5 mL, add it to the contact angle test sample tube, place it in the sample tube rack and place it in an oven at 140℃ for 30 min, then add 5 wt% of regenerator, and place the sample in the high-level heat preservation equipment in the contact angle tester at 140℃ for 1 h for heat preservation and penetration.

[0028] (2) Then, a contact angle test was conducted. While the asphalt was being insulated, the glass slide was also placed in the insulated chamber of the contact angle analyzer. The instrument was adjusted so that the asphalt slowly dripped onto the surface of the glass slide. To prevent air bubbles from forming in the initial droplets, the first two drops pushed out by the instrument were wiped away (air bubbles were squeezed out). Data was recorded starting from the third drop, for a total of 50 drops. The contact angle data at the 10th, 20th, 30th, 40th, and 50th drops were used to evaluate the penetration effect of the high-penetration temperature regenerator. The contact angle test temperature between the asphalt and the glass slide was calculated to be 140℃. The total measurement time for the contact angle data was 1 minute, with a 1-second interval between measurements. A total of 60 contact angle data were measured for each group. See the contact angle test images for details. Figure 2 ;

[0029] (3) Based on the obtained data, plot a scatter plot of the contact angle versus time, and perform a power function y = ax b Fitting.

[0030] In this invention, the index for evaluating the regenerant's penetration effect is calculated as follows: when the temperature is 140℃, the change in contact angle-time follows a power function curve relationship, with a fitting coefficient R... 2 All are greater than 0.99, indicating a good correlation for the power function y = ax b The variation characteristics of the contact angle of asphalt on the aggregate surface are determined by 'a' and 'b'. 'a' represents the contact angle at 1 second when the asphalt just comes into contact with the aggregate, which can be considered the initial state of the contact angle; 'b' represents the paving rate of the asphalt on the aggregate surface. Power function fitting was performed on the contact angle-time scatter plots of sequentially dripping 10, 20, 30, 40, and 50 droplets, and the results are shown below. Figure 3 As shown, the larger the absolute value of b, the faster the paving rate, which indicates a better penetration effect of the regenerator.

[0031]

[0032] Different droplets represent samples at different depths in the sample tube. As shown in the table above, the spreading rate of droplets from the high-permeability warm-temperature regenerator at all locations in the sample tube is higher than that of the ordinary regenerator. This indicates that the high-permeability warm-temperature regenerator has a better penetration effect, and the evaluation method is reasonable.

[0033] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for evaluating the permeability of regenerants based on contact angle testing, characterized in that, The steps are as follows: Step 1. Heat the aged asphalt to a fluid state, draw 0.5 mL with a glass syringe, add it to the contact angle test sample tube, place it in the sample tube rack in the oven, select the temperature to be evaluated for permeability, i.e., set the temperature and keep it warm for 30 min, then add 5 wt% of recycling agent to obtain the sample, place the sample in the high-level heat preservation device in the contact angle tester and keep it warm and permeate for 1 h at the set temperature. Step 2. Then, conduct the contact angle test. While the asphalt is being insulated, place the glass slide in the insulated chamber of the contact angle tester. Adjust the instrument so that the asphalt drips onto the surface of the glass slide. To prevent air bubbles from forming in the initial droplets, wipe away the first two droplets pushed out by the instrument. Start recording from the third drop and record a total of 50 drops. Take the contact angle data at 10, 20, 30, 40, and 50 drops to evaluate the penetration effect of the recycling agent. Calculate the contact angle between the asphalt and the glass slide. The test temperature is the set temperature. The total measurement time for the contact angle data is 1 minute. Measure the contact angle once every 1 second. A total of 60 contact angle data are measured for each group. Step 3. Plot a scatter plot of the contact angle versus time based on the obtained data, and then apply the power function y=ax. b The fitting process shows that the variation characteristics of the contact angle of asphalt on the aggregate surface are determined by a and b. Here, a represents the contact angle of asphalt at 1 second when it just comes into contact with the aggregate, which can be regarded as the initial state of the contact angle; b represents the paving rate of asphalt on the aggregate surface. Power function fitting is performed on the contact angle-time scatter plot of the sequentially dripping droplets. Step 4. Use the b-value to evaluate the permeability of the recycling agent. The larger the absolute value of b, the faster the paving rate, which indicates that the asphalt is softer and the more recycling agent permeates.

2. The method for evaluating the permeability of regenerant based on contact angle testing according to claim 1, characterized in that, The contact angle tester is the DSA-100 optical contact angle analyzer from Kruss GmbH, Germany.

3. The method for evaluating the permeability of regenerant based on contact angle testing according to claim 1, characterized in that, In step one, the aged asphalt is aged using RTFOT aging equipment for a time delay of 720 minutes to simulate the road surface aging asphalt with an actual service life of 15 years.

4. An index for evaluating the permeability of regenerants based on the method of claim 1, characterized in that, The index is the paving rate b of asphalt on the aggregate surface.

5. The index for evaluating the permeability of regenerants according to claim 4, characterized in that, The larger the absolute value of b, the faster the paving rate, indicating a better recycling agent penetration effect.

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