Foamed asphalt residual water microscopic quantitative characterization method based on three-dimensional X-ray

Abstract

The invention discloses a three-dimensional X-ray-based foamed asphalt residual water microcosmic quantitative characterization method, and belongs to the technical field of road engineering foamed asphalt warm mixing, and the method comprises the following steps: adding a warm mixing agent into asphalt preheated in advance to form foamed asphalt, and standing; pouring the foamed asphalt after standing into a test tube, sealing the test tube with a rubber plug, and immediately putting the test tube into liquid nitrogen for quenching to prepare a foamed asphalt observation sample; placing the sample in an X-ray three-dimensional microscope to shoot an image, and then importing the image into ImageJ software; the method comprises the following steps of: performing polygon point selection on bubbles in an image by using a Polygon selection module of software, then running a Measure function in an Analyze module, popping up a Results interface, and summing the calculation area of each bubble. According to the method, a large amount of experimental research on selection of the foaming water consumption or the types of the warm mixing agents in practical application is reduced, the application range is wide, and theoretical guidance is provided for selection of the mixing amount and the types of the warm mixing agents in the foamed asphalt WMA technology.

Description

Technical Field

[0001] The invention relates to the field of foamed asphalt warm mix in road engineering, and in particular to a microscopic quantitative characterization method for residual water in foamed asphalt based on three-dimensional X-rays. Background Art

[0002] Asphalt mixture is the main paving material for highways. At present, it mainly relies on hot mix technology (HMA) for large-scale production. This technology has high energy consumption and emits a large amount of greenhouse gases, which has a great impact on the environment. China has gradually applied warm mix technology (WMA) to asphalt mixture production. Compared with HMA, WMA can reduce the mixing and compaction temperature of asphalt mixture by 20-40℃. In order to reduce the cost of the project, the foamed asphalt WMA technology is currently widely used, which is divided into two forms: water foaming and hydrous mineral foaming. However, a large number of studies have shown that if there is too much residual water after foaming, the performance of asphalt will be significantly reduced. By studying the effect of foaming water consumption on the dispersibility and low-temperature performance of asphalt, it is found that water has a negative effect on the low-temperature performance of foamed warm mix asphalt. The residual water in the asphalt mixture will also reduce the surface free energy of the asphalt-aggregate interface, causing its adhesion performance to decrease, thereby affecting the water stability of the pavement. At present, the research on residual water is limited to qualitative analysis. It is difficult to quantitatively characterize the residual water in foamed asphalt by measuring the performance of foamed asphalt to compare the amount of residual water in different samples and analyze the impact on the performance of foamed asphalt. In addition, when foamed asphalt is foamed at high temperature, the water content gradually changes from liquid to gas, and the total mass of foamed asphalt gradually decreases. The traditional weighing method is not accurate. Therefore, the selection of the amount of water used for foaming or the type of warm mix agent still relies on a large number of experimental studies. Summary of the invention

[0003] The purpose of the present invention is to provide a microscopic quantitative characterization method for residual water in foamed asphalt based on three-dimensional X-rays, which uses liquid nitrogen quenching to capture the solid state of foamed asphalt at a certain moment and make a test tube sample. The three-dimensional X-ray is used to observe the residual moisture in the solid sample, and combined with the regional image statistical algorithm, the residual water content in the foamed asphalt is quantitatively analyzed in the form of calculating the bubble area, thereby providing a simpler method for reasonably selecting the amount of water used for foaming or the type of warm mix agent.

[0004] To achieve the above object, the present invention provides a method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray, comprising the following steps: (1) Preparation of foamed bitumen residual water samples; (2) Place the foamed bitumen residual water sample in an X-ray three-dimensional microscope to capture images and ensure that the exported images have the same size; (3) Import the image exported in step (2) into ImageJ software; (4) Use the Polygon selections module of the ImageJ software in step (3) to perform polygonal point selection on the bubbles in the image obtained in step (2), then run the Measure in the Analyze module, and the Results interface will pop up automatically, and the calculated area of ​​each bubble will be obtained; (5) Sum the calculated areas of all bubbles.

[0005] Preferably, preparing the foamed bitumen residual water sample comprises the following steps: Add warm mix agent to the preheated asphalt, stir appropriately to form foamed asphalt, let it stand, pour the foamed asphalt after different standing times into a test tube, seal it with a rubber stopper and immediately put it into liquid nitrogen for rapid cooling to obtain a foamed asphalt residual water sample.

[0006] Preferably, the asphalt is any one of base asphalt, SBS modified asphalt, and rubber powder modified asphalt; and the warm-mixing agent is any one of water, zeolite warm-mixing agent, and red mud warm-mixing agent.

[0007] Preferably, the preheating temperature is 140-170° C.; the stirring is mechanical stirring, the time is 30-60s, and the rotation speed is 600-1200rpm.

[0008] Preferably, the different standing times are 2 min, 60 min and 120 min respectively.

[0009] Preferably, the X-ray exposure time is 1000ms, the tube voltage is 110kV, the current is 150uA, the image resolution is 2000×2000, the width and height are 2000 pixels respectively, and the horizontal and vertical resolutions are both 96dpi.

[0010] Preferably, the polygonal points are selected to calculate the area, the number of selected points is between 10 and 30, and the number of selected points for each bubble in the same image and in different images remains consistent.

[0011] Therefore, the present invention adopts the above-mentioned three-dimensional X-ray-based microscopic quantitative characterization method for residual water in foamed asphalt, and the technical effects are as follows: (1) The traditional weighing method has poor accuracy in quantitative characterization of residual water in foamed asphalt due to continuous evaporation of water. The present invention combines indoor experiments with software analysis and calculation to expand the research on residual water in foamed asphalt from qualitative analysis to quantitative characterization in the form of calculating the residual water area in foamed asphalt, providing a simple and more accurate new method.

[0012] (2) The present invention proposes a method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-rays. In the field of foamed asphalt WMA technology, the area calculation result can be used as an indicator to evaluate the performance of warm mix agents, which is beneficial to reduce a large amount of experimental research on the amount of water used for foaming or the selection of the type of warm mix agent in practical applications, and provides theoretical guidance for the selection of the dosage and type of warm mix agent in foamed asphalt WMA technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a schematic diagram of the overall process of the present invention; Figure 2 is a captured image in some embodiments; Figure 3 It is the relevant calculation module of ImageJ software used in the embodiment; Figure 4 A schematic diagram of polygon point selection using ImageJ software for a certain embodiment; Figure 5 The area calculation results using ImageJ software are shown for a certain embodiment; Figure 6 The figure is a comparison of the area calculation results of the embodiments of the present invention. DETAILED DESCRIPTION

[0014] The technical solution of the present invention is further described below through the accompanying drawings and embodiments.

[0015] Unless otherwise defined, technical or scientific terms used in the present invention shall have the common meanings understood by one having ordinary skills in the field to which the present invention belongs.

[0016] Example 1 A method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-rays, comprising the following steps: (1) Add 2% by mass of water to the base asphalt preheated at 145°C, stir for 30 seconds and control the speed of the stirring machine to 700 rpm to form foamed asphalt, and let it stand for use.

[0017] (2) Pour the foamed asphalt into a test tube after standing for 2 minutes, seal it with a rubber stopper, and immediately put it into liquid nitrogen for rapid cooling.

[0018] (3) When the foamed asphalt has been left to stand for 60 minutes, repeat step (2).

[0019] (4) When the foamed asphalt has been standing for 120 min, repeat step (2) to obtain water-foamed foamed matrix asphalt samples at three different times.

[0020] (5) Adjust the parameters of the X-ray 3D microscope, set the X-ray exposure time to 1000ms, the tube voltage to 110kV, the current to 150uA, set the exported image resolution to 2000×2000, the width and height to 2000 pixels respectively, and the horizontal and vertical resolutions to 96dpi.

[0021] (6) Three water-blown foam matrix asphalt samples are placed in the X-ray three-dimensional microscope that has been debugged in step (5) and photographed to export images.

[0022] (7) Import the images in step (6) into ImageJ software respectively, and use the Polygon selections module in the software to perform polygonal point selection on all the blisters in the images based on the regional image statistical algorithm, with 20 points selected for each blisters.

[0023] (8) Run the Measure function of the Analyze module in the software. The Area in the Results interface that pops up is the calculated area of ​​each bubble.

[0024] (9) Sum the calculated areas of all bubbles.

[0025] Example 2 Same as Example 1, except that the preheating temperature of the base asphalt is 130°C.

[0026] Example 3 The same as Example 1, except that the warm mix agent is a zeolite warm mix agent with a mass percentage of 6% of the base asphalt, and zeolite foamed base asphalt samples are obtained at three different times.

[0027] Example 4 The same as Example 1, except that the warm mix agent is a red mud warm mix agent with 15% by mass of base asphalt, and red mud foamed base asphalt samples are obtained at three different times.

[0028] Example 5 A microscopic quantitative characterization method for residual water in foamed asphalt based on three-dimensional X-rays, the steps are as follows:.

[0029] (1) Add 2% water by mass of SBS modified asphalt to the SBS modified asphalt preheated at 170°C, stir for 45 seconds and control the speed of the stirring machine to 1000 rpm to form foamed asphalt, and let it stand for use.

[0030] (2) Pour the foamed asphalt into a test tube after standing for 2 minutes, seal it with a rubber stopper, and immediately put it into liquid nitrogen for rapid cooling.

[0031] (3) When the foamed asphalt has been left to stand for 60 minutes, repeat step (2).

[0032] (4) When the foamed asphalt has been standing for 120 min, repeat step (2) to obtain water-blown SBS modified asphalt samples at three different times.

[0033] (5) Adjust the parameters of the X-ray 3D microscope, set the X-ray exposure time to 1000ms, the tube voltage to 110kV, the current to 150uA, set the exported image resolution to 2000×2000, the width and height to 2000 pixels respectively, and the horizontal and vertical resolutions to 96dpi.

[0034] (6) Three water-blown SBS modified asphalt samples are placed in the X-ray three-dimensional microscope that has been debugged in step (5) and photographed to export images.

[0035] (7) Import the images in step (6) into ImageJ software respectively, and use the Polygon selections module in the software to perform polygonal point selection on all the blisters in the images based on the regional image statistical algorithm, with 20 points selected for each blisters.

[0036] (8) Run the Measure function of the Analyze module in the software. The Area in the Results interface that pops up is the calculated area of ​​each bubble.

[0037] (9) Sum the calculated areas of all bubbles.

[0038] Example 6 Same as Example 5, except that the preheating temperature of the SBS modified asphalt is 150°C.

[0039] Example 7 The same as Example 5, except that the warm mix agent is a zeolite warm mix agent with a mass percentage of 6% of SBS modified asphalt, and zeolite foamed SBS modified asphalt samples are obtained at three different times.

[0040] Example 8 The same as Example 5, except that the warm mix agent is a red mud warm mix agent with 15% by mass of SBS modified asphalt, and zeolite foamed SBS modified asphalt samples are obtained at three different times.

[0041] Comparative Example 1 Same as Example 1, except that no warm mix agent is added to the base asphalt.

[0042] Comparative Example 2 Same as Example 5, except that no warm mix agent is added to the SBS modified asphalt.

[0043] Table 1 Area calculation results of the above embodiments and comparative examples

[0044] The results are presented in the form of area calculation to characterize the residual water in different types of foamed asphalt. The residual water content in foamed asphalt obtained by different warm mix agent types and foaming conditions is shown in a simple way. The quantitative characterization method and sample preparation method of residual water in foamed asphalt described in the present invention are also applicable to other types of foamed asphalt. It can be seen from the area calculation results that compared with water foaming and zeolite foaming, less water remains in the asphalt after the foaming is completed by using red mud foaming; regardless of the type of asphalt or warm mix agent, a low foaming temperature will result in more water remaining in the asphalt; as shown in Comparative Examples 1 and 2, when no warm mix agent is added for foaming, there is no residual water in the asphalt, and the final area calculation results are all 0.

[0045] Therefore, the present invention adopts the above-mentioned three-dimensional X-ray-based microscopic quantitative characterization method for residual water in foamed asphalt. In the field of foamed asphalt WMA technology, the area calculation result can be used as an indicator for evaluating the performance of warm mix agents, which is beneficial to reduce a large amount of experimental research on the amount of water used for foaming or the type of warm mix agent in practical applications, and provides theoretical guidance for the selection of the dosage and type of warm mix agent in foamed asphalt WMA technology.

[0046] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that they can still modify or replace the technical solution of the present invention with equivalents, and these modifications or equivalent replacements cannot cause the modified technical solution to deviate from the spirit and scope of the technical solution of the present invention.

Claims

1. A method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray, characterized in that: The following steps are involved: (1) Preparation of foamed bitumen residual water samples; (2) Place the foamed bitumen residual water sample in an X-ray three-dimensional microscope to capture images and ensure that the exported images have the same size; (3) Import the image exported in step (2) into ImageJ software; (4) Use the Polygon selections module of the ImageJ software in step (3) to perform polygonal point selection on the bubbles in the image obtained in step (2), then run the Measure in the Analyze module, and the Results interface will pop up automatically, and the calculated area of ​​each bubble will be obtained; (5) Sum the calculated areas of all bubbles.

2. The method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray according to claim 1, characterized in that: The preparation of the foamed bitumen residual water sample comprises the following steps: Add warm mix agent to the preheated asphalt, stir appropriately to form foamed asphalt, let it stand, pour the foamed asphalt after different standing times into a test tube, seal it with a rubber stopper and immediately put it into liquid nitrogen for rapid cooling to obtain a foamed asphalt residual water sample.

3. The method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray according to claim 2, characterized in that: It is any one of base asphalt, SBS modified asphalt, and rubber powder modified asphalt; the warm mixing agent is any one of water, zeolite warm mixing agent, and red mud warm mixing agent.

4. The method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray according to claim 2, characterized in that: The preheating temperature is 140-170°C; the stirring is mechanical stirring, the time is 30-60s, and the rotation speed is 600-1200rpm.

5. The method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray according to claim 2, characterized in that: The different standing times are 2min, 60min and 120min respectively.

6. The method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray according to claim 1, characterized in that: The X-ray exposure time is 1000ms, the tube voltage is 110kV, the current is 150uA, the image resolution is 2000×2000, the width and height are 2000 pixels respectively, and the horizontal and vertical resolutions are both 96dpi.

7. The method for microscopic quantitative characterization of residual water in foamed asphalt based on three-dimensional X-ray according to claim 1, characterized in that: The polygonal points are selected to calculate the area. The number of selected points is between 10 and 30. The number of selected points for each bubble in the same image and different images remains consistent.

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