Method for detecting toughness of high-viscosity modified asphalt

Abstract

The invention belongs to the technical field of road asphalt detection, and particularly relates to a method for detecting the toughness of high-viscosity modified asphalt, which comprises the following steps of: preparing a high-viscosity modified asphalt sample by adopting an 8-shaped mold, and testing the ductility of the high-viscosity modified asphalt at 5 DEG C to obtain a load-displacement curve; selecting the lowest point in the curve part opposite to the x axis on the curve, intersecting the vertical line of the lowest point with the x axis, respectively calculating the load-displacement curve area corresponding to the lowest point and the whole load-displacement curve area, and then calculating the toughness and viscosity toughness of the high-viscosity modified asphalt by using a toughness and viscosity toughness calculation model. According to the technical scheme provided by the invention, the problem that the toughness cannot be calculated by a load-displacement bimodal curve of the high-viscosity modified asphalt is solved.

Description

Technical Field

[0001] The invention belongs to the technical field of road asphalt detection, and in particular relates to a method for detecting the toughness of high-viscosity modified asphalt. Background Art

[0002] The viscosity-toughness test of asphalt is usually used as a means to evaluate the quality of modified asphalt. It was first proposed by Benson in the 1950s. The test can obtain the relationship curve between asphalt deformation and load. After the test, two indicators are output through calculation, which are called viscosity-toughness and toughness. Among them, viscosity-toughness can reflect both the viscoelastic effect of asphalt and the amount of energy it possesses; toughness can reflect the ability of asphalt to resist fracture and delayed destruction in the yield stage. The viscosity-toughness test must first preheat the mold for at least 1 hour, wipe the hemispherical head clean, pour 50g of asphalt sample into the container, quickly insert the hemispherical head into the asphalt sample, and fix the positioning nut. Remember that the hemispherical head cannot be immersed in the sample, but should be flush with the surface of the asphalt sample. After cooling, put it in a 25℃ water bath for at least 1.5 hours. After the insulation is over, fix the viscosity-toughness mold on the testing machine, and immediately start vertical stretching at a speed of 500mm / min. It ends when it stretches to 300mm. The test curve is as follows Figure 1 and Figure 2 shown.

[0003] For conventional asphalt, the tangent CE is found according to the method required by the operating regulations, and the viscosity-toughness and toughness data are obtained by calculating the envelope area. However, for high-viscosity modified asphalt, the load-displacement curve is slightly different. The relationship curve of ordinary asphalt is a single peak (such as Figure 1 ), and after the load reaches the maximum value, there is a long downward curve, which makes it easy to get the tangent CE; the load-displacement curve of high-viscosity modified asphalt is double-peaked (such as Figure 2 ), after reaching the load peak, the load will drop briefly and then continue to increase, which leads to two situations: the first is that point E is close to F, resulting in a very small toughness result; the second is that point E falls outside the AF range. If the area is still calculated as the toughness as required by the specification, part of the area will be negative, which is obviously unreasonable; at the same time, the high-viscosity modified asphalt has a large cohesive force, and the hemispherical head may fall out of the asphalt sample during the test; the current traditional viscosity-toughness test methods cannot accurately calculate the viscosity-toughness and toughness of high-viscosity modified asphalt. Summary of the invention

[0004] The purpose of the present invention is to provide a method for detecting the toughness of high-viscosity modified asphalt, which can accurately detect the viscosity, toughness and toughness of high-viscosity modified asphalt or modified asphalt with greater cohesion, so as to solve the problems existing in the above-mentioned background technology.

[0005] To achieve the above objectives, this application is implemented through the following technical solutions:

[0006] A method for testing the toughness of high-viscosity modified asphalt, using a force-ductility testing machine to perform a viscosity-toughness test, comprises the following steps:

[0007] S1. Use a mold to prepare samples of high-viscosity modified asphalt, conduct a 5°C ductility test on the high-viscosity modified asphalt, and obtain a load-displacement curve;

[0008] S2. For the load-displacement curve of step S1, select the lowest point C in the curve portion opposite to the x-axis, and draw a vertical line through the lowest point C that intersects the x-axis at point F. The area enclosed by line segment OF, line segment CF, and the load-displacement curve between points O and C is S. 1 The area enclosed by the load-displacement curve and the x-axis is S 2 , calculate S 1 The area of ​​x 1 ,S 2 The area of ​​x 2 ;

[0009] S3, toughness and viscosity-toughness calculation model is: ; ; where R 2 =1, r 2 =0.9017;y 1 Represents toughness, y 2 Indicates viscosity and toughness.

[0010] Furthermore, in step S1, the mold used is an "8"-shaped mold.

[0011] Furthermore, in step S1, the steps of preparing the high viscosity modified asphalt sample are as follows:

[0012] S11, heating the high viscosity modified asphalt to 175-185°C;

[0013] S12. When pouring the mold, slowly move the high-viscosity modified asphalt from one end of the mold to the other end, back and forth several times, until the mold is filled and higher than the set height of the mold, and cool at room temperature for at least 1.5 hours;

[0014] S13. Use a hot scraper to scrape the sample from the middle to both ends, scrape off the sample that is higher than the mold, make the sample flush with the mold, and put it in a 5℃±0.1℃ water bath to keep warm for 1.5 hours.

[0015] Furthermore, the high-viscosity modified asphalt after sample preparation is subjected to a ductility test using a force-ductility instrument. After the test, the displacement and load data are output and a load-displacement curve is plotted.

[0016] Furthermore, when the ductility test is performed using a force-ductility instrument, horizontal stretching is started at a speed of 50 mm / min.

[0017] Furthermore, in step S2, the load-displacement curve between the highest load point of the load-displacement curve and the X-axis is a straight line and is parallel to the line segment CF.

[0018] The beneficial effects of the present invention are:

[0019] The detection method of the present invention solves the problem that the toughness cannot be calculated using the double-peak curve of the load-displacement of high-viscosity modified asphalt. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 This is the load-deformation curve of the viscosity-toughness test.

[0021] Figure 2 This is the load-deformation curve of the high viscosity asphalt viscosity-toughness test.

[0022] Figure 3 It is a load-displacement curve diagram of the force-ductility test of the high-viscosity modified asphalt of the present invention. DETAILED DESCRIPTION

[0023] The technical solution of the present invention is described in detail below through examples. The following examples are merely exemplary and can only be used to explain and illustrate the technical solution of the present invention, but cannot be construed as limiting the technical solution of the present invention.

[0024] Example 1

[0025] Preparation of high viscosity modified asphalt:

[0026] Sample GNT-1: Heat the base asphalt 70# to 165℃, then add 5.5% softening oil and stir evenly; add 9% SBS, continue to heat to 180℃, stir evenly, and grind with a colloid mill; after grinding, add 0.3% stabilizer and develop to obtain high-viscosity modified asphalt; the development temperature is 183℃, the development time is 5h, and the stirring rate is 450r / min.

[0027] Testing steps:

[0028] a) Use the "8"-shaped mold to prepare the sample, conduct a 5℃ ductility test on the high-viscosity modified asphalt, obtain the load and tensile displacement data, and draw a curve, such as Figure 3 shown.

[0029] b) Calculate the area of ​​the load-displacement curve obtained in the force-ductility test and record x 1 Area and x 2 area.

[0030] c) Substitute the values ​​of X1 and X2 into the toughness and viscosity-toughness data model: ; ; where R 2 =1, r 2 =0.9017;y 1 Represents toughness, y 2 It represents viscosity-toughness, and obtains toughness and viscosity-toughness.

[0031] In step a), the sample preparation temperature of high-viscosity modified asphalt is 180°C. When pouring the mold, slowly move from one end of the mold to the other end, back and forth several times, until the mold is filled and part of the mold is higher than the mold, and then cool at room temperature for 1.5 hours. Use a hot scraper to scrape the sample from the middle to both ends, scrape off the sample that is higher than the mold, make the sample flush with the mold, and put it in a 5°C water bath for 1.5 hours. Use a force ductility tester to perform the ductility test (start horizontal stretching at a speed of 50mm / min). After the test, output the displacement and load data and draw the curve.

[0032] Example 2

[0033] Sample GNT-2: Heat the base asphalt 70# to 165°C, then add 4.0% softening oil and stir evenly; add 7.2% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; add 0.2% stabilizer after grinding, and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 8h, and the stirring rate is 450r / min. The detection steps are the same as those in Example 1.

[0034] Example 3

[0035] Sample GNT-3: Heat the base asphalt 70# to 165°C, then add 6% softening oil and stir evenly; add 10% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; add 0.3% stabilizer after grinding and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 8h, and the stirring rate is 450r / min. The detection steps are the same as those in Example 1.

[0036] Example 4

[0037] Sample GNT-4: Heat the base asphalt 70# to 165°C, then add 3.2% softening oil and stir evenly; add 5.0% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; add 0.3% stabilizer after grinding, and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 5h, and the stirring rate is 450r / min. The detection steps are the same as those in Example 1.

[0038] The force-ductility tests of high-viscosity modified asphalt of Examples 1 to 4 are shown in Table 1.

[0039] Table 1 Calculation values ​​of the force-ductility test area for high-viscosity modified asphalt

[0040]

[0041] Comparative Example 1

[0042] The sample is the same as the example: heat the base asphalt 70# to 165°C, then add 5.5% softening oil and stir evenly; add 9% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; after grinding, add 0.3% stabilizer and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 5h, and the stirring rate is 450 r / min.

[0043] According to the viscosity-toughness test operating procedures, samples were prepared and tested using the SYD-0624 viscosity-toughness testing machine produced by Shanghai Changji Geological Instrument Co., Ltd. The tensile rate was 500 mm / min, and the test ended when the stretching reached 300 mm. The instrument automatically calculated the toughness and viscosity-toughness values.

[0044] Comparative Example 2

[0045] The sample is the same as Example 2: heat the base asphalt 70# to 165°C, then add 4.0% softening oil and stir evenly; add 7.2% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; after grinding, add 0.2% stabilizer and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 8 h, and the stirring rate is 450 r / min.

[0046] According to the viscosity-toughness test operating procedures, samples were prepared and tested using the SYD-0624 viscosity-toughness testing machine produced by Shanghai Changji Geological Instrument Co., Ltd. The tensile rate was 500 mm / min, and the test ended when the stretching reached 300 mm. The instrument automatically calculated the toughness and viscosity-toughness values.

[0047] Comparative Example 3

[0048] The sample is the same as Example 3: heat the base asphalt 70# to 165°C, then add 6% softening oil and stir evenly; add 10% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; after grinding, add 0.3% stabilizer and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 8 h, and the stirring rate is 450 r / min.

[0049] According to the viscosity-toughness test operating procedures, samples were prepared and tested using the SYD-0624 viscosity-toughness testing machine produced by Shanghai Changji Geological Instrument Co., Ltd. The tensile rate was 500 mm / min, and the test ended when the stretching reached 300 mm. The instrument automatically calculated the toughness and viscosity-toughness values.

[0050] Comparative Example 4

[0051] The sample is the same as Example 4: heat the base asphalt 70# to 165°C, then add 3.2% softening oil and stir evenly; add 5.0% SBS, continue to heat to 180°C, stir evenly, and grind with a colloid mill; after grinding, add 0.3% stabilizer and develop to obtain high-viscosity modified asphalt; the development temperature is 183°C, the development time is 5 h, and the stirring rate is 450 r / min.

[0052] According to the viscosity-toughness test operating procedures, samples were prepared and tested using the SYD-0624 viscosity-toughness testing machine produced by Shanghai Changji Geological Instrument Co., Ltd. The tensile rate was 500 mm / min, and the test ended when the stretching reached 300 mm. The instrument automatically calculated the toughness and viscosity-toughness values. The comparative test data are shown in Table 2.

[0053] Table 2 SYD-0624 viscosity and toughness testing machine test data

[0054]

[0055] Embodiments 1, 2, 3, and 4 correspond to proportions 1, 2, 3, and 4 respectively. It can be seen from the data that the viscosity-toughness calculated by the force-ductility meter has a good correlation with the actual measured value. When a double peak appears, the viscosity-toughness testing machine cannot correctly measure the toughness result, while the force-ductility meter can calculate the toughness. This method solves the problem that the toughness cannot be calculated by the double peak curve of the load-displacement of high-viscosity modified asphalt.

[0056] The above specific implementation cases are only exemplary, and are intended to enable professionals in the field to better understand the content of the present invention, and should not be understood as limiting the scope of protection of the present invention. As long as it is an equivalent change or revision made according to the spirit disclosed by the present invention, it should be included in the scope of protection of the present invention.

Claims

1. A method for testing the toughness of high-viscosity modified asphalt, using a force-ductility testing machine to test the toughness, characterized in that: The following steps are involved: S1. Use a mold to prepare samples of high-viscosity modified asphalt, conduct a 5°C ductility test on the high-viscosity modified asphalt, and obtain a load-displacement curve; S2. For the load-displacement curve of step S1, select the lowest point C in the curve portion opposite to the x-axis, and let the vertical line through the lowest point C intersect the x-axis at point F, where the area enclosed by line segment OF, line segment CF and the load-displacement curve between points O and C is S1, and the area enclosed by the load-displacement curve and the x-axis is S2. The area of ​​S1 is calculated to be x1, and the area of ​​S2 is calculated to be x2; S3, toughness and viscosity-toughness calculation model is: ; ; where R 2 =1,r 2 =0.9017; y1 represents toughness, and y2 represents viscosity-toughness.

2. The method for testing toughness of high-viscosity modified asphalt according to claim 1, characterized in that: In step S1, the mold used is an "8"-shaped mold.

3. The method for testing toughness of high viscosity modified asphalt according to claim 2, characterized in that: In step S1, the steps of preparing the high viscosity modified asphalt sample are as follows: S11, heating the high viscosity modified asphalt to 175-185°C; S12. When pouring the mold, slowly move the high-viscosity modified asphalt from one end of the mold to the other end, back and forth several times, until the mold is filled and higher than the set height of the mold, and cool at room temperature for at least 1.5 hours; S13. Use a hot scraper to scrape the sample from the middle to both ends, scrape off the sample that is higher than the mold, make the sample flush with the mold, and put it in a 5℃±0.1℃ water bath to keep warm for 1.5 hours.

4. The method for testing toughness of high-viscosity modified asphalt according to claim 3, characterized in that: The high-viscosity modified asphalt after sample preparation is subjected to ductility test using a force-ductility instrument. After the test, the displacement and load data are output and the load-displacement curve is plotted.

5. The method for testing toughness of high viscosity modified asphalt according to claim 4, characterized in that: When using a force-extension instrument to perform the ductility test, start horizontal stretching at a speed of 50 mm / min.

6. The method for testing toughness of high viscosity modified asphalt according to claim 1, characterized in that: In step S2, the load-displacement curve between the highest load point of the load-displacement curve and the X-axis is a straight line and is parallel to the line segment CF.

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