A method for determining the optimal construction temperature of modified asphalt at different modifier dosages

Abstract

The invention discloses a method for determining the optimal construction temperature of modified asphalt under different modifier dosages, comprising: S1, detecting the viscosity of the modified asphalt sample at a temperature; S2, drawing a curve with the modifier dosage as the abscissa and the viscosity of the modified asphalt sample at a temperature T1 as the ordinate, and confirming the mutation point O T1 ; S3, temperature T1 is the optimal construction temperature of modified asphalt under a specific modifier dosage; S4, obtain the relationship between the modified asphalt modifier dosage and the optimal construction temperature, and determine the optimal construction temperature of modified asphalt under the dosage according to the modifier dosage of the modified asphalt during actual construction. The method of the present invention can construct a corresponding relationship between the dosage of a specific modifier and the optimal construction temperature of modified asphalt, and can also construct an optimal construction temperature database of modified asphalt containing different modifiers, eliminating the influence of human factors and uncertain information in the existing construction temperature determination.

Description

Technical Field

[0001] The invention belongs to the technical field of pavement construction, and in particular relates to a method for determining an optimal construction temperature in modified asphalt. Background Art

[0002] With the rapid development of road construction technology, especially polymer modification technology, the road performance such as high temperature performance, low temperature performance and durability can be significantly improved. Among them, the thermoplastic polymer styrene-butadiene-styrene (SBS) is the most successfully applied polymer modifier. SBS modified asphalt has excellent high temperature rutting resistance and good low temperature crack resistance, and is one of the main materials used in asphalt road construction. Compared with base asphalt, SBS modified asphalt shows great advantages in physical properties, storage stability and cost-effectiveness. In actual use, the construction temperature of modified asphalt will affect the aging degree of asphalt. Selecting a suitable applicable temperature can save energy, reduce carbon emissions, and make asphalt have better road performance. However, in the existing technology and existing construction methods, the approximate construction temperature is often selected on site based on experience, and no distinction is made between modified asphalts of different types of modifiers. The determination of construction temperature lacks an effective unified standard and is affected by a variety of human factors, making it difficult to fully exert the optimal performance of modified asphalt. Summary of the invention

[0003] In order to overcome the problems in the prior art, the present invention provides a method for determining the optimal construction temperature in modified asphalt. At different temperatures, by establishing a viscosity change curve of modified asphalt with different modifier dosages, the curve is differentiated once to obtain a mutation point O where the viscosity changes with the modifier dosage, and the horizontal coordinate value corresponding to the mutation point O is the upper limit of the modifier dosage in the modified asphalt at the construction temperature. The reasonable construction temperature of the modified asphalt at this dosage is the temperature corresponding to the viscosity at this time.

[0004] In order to solve the above technical problems, the technical solutions proposed by the present invention are as follows:

[0005] A method for determining the optimal construction temperature of modified asphalt under different modifier dosages comprises the following steps:

[0006] S1. Prepare modified asphalt samples with different modifier dosages and test the viscosity of the samples at different temperatures;

[0007] S2. At temperature T1, a curve is drawn with the modifier dosage as the horizontal axis and the viscosity of the modified asphalt sample as the vertical axis, and the mutation point where the viscosity changes with the modifier dosage is determined based on the curve. T1 ;

[0008] S3, mutation point O T1 The corresponding horizontal axis value is the modifier dosage CT1 , temperature T1 is the mutation point O T1 Corresponding modifier dosage C T1 The best construction temperature for modified asphalt is:

[0009] S4. Test to obtain the mutation point O at different temperatures Tn Tn , get the modifier dosage C Tn The relationship between the modified asphalt and the optimal construction temperature Tn is determined according to the modifier dosage of the modified asphalt during actual construction.

[0010] The design idea of ​​the above technical solution is that viscosity is a measure of the resistance of a fluid to flow, which can characterize the friction resistance between molecules when the fluid flows at different temperatures. By studying the viscosity index of asphalt in a flowing state, the mixing temperature and compaction temperature of various asphalt mixtures can be determined. The US Strategic Research Program (SHRP) uses a Brookfield viscometer to test the viscosity value of asphalt, and my country has also included the Brookfield viscosity test method in the "Test Procedure for Asphalt and Asphalt Mixtures for Highway Engineering" (JTG E20-2019). The present invention establishes a viscosity change curve of modified asphalt with different modifier dosages. When the modifier dosage exceeds a certain value, the viscosity of the modified asphalt will increase sharply. This point is defined as a mutation point (a linear fit is performed on the change trend of the slope of the curve, and the slope suddenly increases at a certain point, which is the mutation point). The modifier dosage corresponding to the mutation point is the key to coordinating the high temperature performance of asphalt and construction workability. The inventors found that when the modifier dosage exceeds the corresponding value of the mutation point, the asphalt viscosity increases sharply, which will greatly increase the difficulty and cost of construction. That is, it is reasonable to select this temperature as the construction temperature within this value range.

[0011] As a further preferred embodiment of the above technical solution, the mutation point O in S2 T1 And the mutation point O described in S3 Tn Determined by:

[0012] The curve is differentiated once to obtain a derivative curve of viscosity and dosage; when the slope of the derivative curve changes suddenly with the increase of the modifier dosage, the corresponding modifier dosage is counted as the mutation point.

[0013] As a further preferred embodiment of the above technical solution, in step S1, the dosage of the modifier varies in a linear gradient between 1% and 10%.

[0014] As a further preferred embodiment of the above technical solution, in step S1, the test temperature range is 80-210°C.

[0015] As a further preferred embodiment of the above technical solution, in step S1, when detecting the viscosity, the torque range of the viscometer is controlled to be 10%-98%.

[0016] As a further preferred embodiment of the above technical solution, the modifier is styrene-butadiene-styrene or a mixture containing styrene-butadiene-styrene.

[0017] As a further preferred embodiment of the above technical solution, the relationship between the modifier dosage and the optimal construction temperature in modified asphalts with different modifiers is tested according to methods S1 to S4, and a database of optimal construction temperatures for different modifiers is constructed; the optimal construction temperature of the modified asphalt is determined according to the type of modifier and the modifier dosage of the modified asphalt during actual construction.

[0018] As a further preferred embodiment of the above technical solution, when the mutation point cannot be determined according to the curve of S2, the viscosity test temperature of the modified asphalt sample is reduced until the mutation point can be determined. If the mutation point is not obvious or cannot be obtained, it means that the asphalt construction temperature is below the test temperature at the tested modifier dosage, so the viscosity test temperature needs to be reduced.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] The present invention provides a method for determining the optimal construction temperature of modified asphalt with different modifier dosages. Through this method, a corresponding relationship between the dosage of a specific modifier and the optimal construction temperature of modified asphalt can be constructed, and an optimal construction temperature database of modified asphalt containing different modifiers can also be constructed. In the actual production process, the construction party is guided to determine the optimal construction temperature according to the type of modifier and the actual dosage of the modifier, eliminating the influence of human factors and uncertain information in the existing construction temperature determination. When the construction is carried out at the optimal construction temperature, the modified asphalt material is easier to lay and level, which can improve the construction efficiency and shorten the construction period; ensure the good adhesion and density of the asphalt mixture, thereby improving the bearing capacity and durability of the road surface. Reasonable determination of the asphalt construction temperature can not only improve the construction quality and efficiency, but also reduce the later maintenance cost and environmental impact. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 is a first derivative graph of the viscosity of modified asphalt at 135°C as a function of modifier dosage in Example 1;

[0023] Figure 2is a first derivative graph of the viscosity of modified asphalt at 175°C as a function of modifier dosage in Example 1;

[0024] Figure 3 is a first derivative graph of the viscosity of modified asphalt at 190°C as a function of the modifier dosage in Example 1;

[0025] Figure 4 is a first derivative graph of the viscosity of modified asphalt at 205°C as a function of the modifier dosage in Example 1;

[0026] Figure 5 is a first derivative graph of the viscosity of modified asphalt at 135°C as a function of modifier dosage in Example 2;

[0027] Figure 6 is a first derivative graph of the viscosity of modified asphalt at 175°C as a function of modifier dosage in Example 2;

[0028] Figure 7 is a first derivative graph of the viscosity of modified asphalt at 190°C as a function of modifier dosage in Example 2;

[0029] Figure 8 is a first derivative graph of the viscosity of modified asphalt at 205°C as a function of modifier dosage in Example 2;

[0030] Fig. 9 is a first derivative graph of the viscosity of modified asphalt at 135°C as a function of modifier dosage in Example 3;

[0031] Fig.10 is a first derivative graph of the viscosity of modified asphalt at 175°C as a function of modifier dosage in Example 3;

[0032] Fig.11 This is the first derivative graph of the viscosity of the modified asphalt at 190°C as a function of the modifier dosage in Example 3. DETAILED DESCRIPTION

[0033] In order to facilitate the understanding of the present invention, the present invention will be described more comprehensively and meticulously below in conjunction with the accompanying drawings and preferred embodiments of the present invention, but the protection scope of the present invention is not limited to the following specific embodiments.

[0034] Unless otherwise defined, all professional terms used below have the same meanings as those generally understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention.

[0035] Unless otherwise specified, various raw materials, reagents, instruments and equipment used in the present invention can be purchased from the market or prepared by existing methods.

[0036] Embodiment 1:

[0037] The method of determining the optimal construction temperature of modified asphalt under different modifier dosages in this embodiment comprises the following steps:

[0038] (1) A certain amount of base asphalt 1 provided by a certain enterprise was weighed and heated to 180°C. A linear SBS (styrene-butadiene-styrene) modifier (the addition amounts were 0, 1%, 2%, 3%, 4%, 5%, 6%, 7%, 8%, and 9%) was first added at a shear rate of 700 r / min. The temperature was maintained at 180°C. The shear rate was then adjusted to 7000 r / min and the temperature was kept constant for shearing for 2 h. The sample was transferred to a disperser and dispersed at a speed of 700 r / min for 2 h to obtain a series of modified asphalt samples. The prepared modified asphalt samples were controlled by a single variable method so that all modified asphalt samples differed only in the amount of SBS modifier added.

[0039] (2) The viscosity of the modified asphalt samples was tested at different temperatures. The test temperature was 80°C-210°C (135, 175, 190 and 205°C were selected in this embodiment). The appropriate rotor model was selected according to the specific test temperature and the type of asphalt sample. The torque reading was controlled to be within the range of 10%-98%. Some test data are shown in Table 1 below:

[0040] Table 1: Relationship between SBS content in SBS modified asphalt and modified asphalt viscosity

[0041]

[0042] (3) At a specific temperature, a curve is drawn with the modifier dosage as the horizontal axis and the viscosity of the modified asphalt sample as the vertical axis; by taking the first derivative of the viscosity curve, the mutation point O where the viscosity of the modified asphalt changes with the modifier dosage is obtained; by taking the derivative of the viscosity curve, the viscosity derivative curve is analyzed. For ease of understanding, Δd is used to represent the viscosity Δη / ΔSBS dosage after differentiation, and the viscosity derivative curve at different temperatures with the SBS dosage is obtained. By taking the first-order derivative of the curve, the mutation points at 135℃, 175℃, 190℃ and 205℃ are determined. The SBS dosage values ​​corresponding to the mutation points are 6.5%, 7.0%, 8.0% and 8.5%, respectively. The first derivative graphs of the viscosity of the modified asphalt changing with the modifier dosage at 135℃, 175℃, 190℃ and 205℃ are shown in the figure below. Figure 1-4 As shown, it shows that at the corresponding modifier dosage at this mutation point, the corresponding temperature can be used as the optimal construction temperature of asphalt. At the same time, at 135°C, when the SBS dosage is about 5%, the viscosity derivative also has a small mutation point, which corresponds to the transition point of the SBS phase in asphalt. Compared with the above mutation points, the mutation trend of this point is not obvious and it is easier to distinguish.

[0043] (4) According to steps (1) to (3), the relationship between the SBS modifier dosage and the optimal construction temperature is obtained, that is, the minimum value of the SBS dosage corresponding to each mutation point is taken as the starting point, that is, when the modifier dosage is ≤6.5%, the corresponding temperature of 135°C is selected as the optimal construction temperature; when the modifier dosage is greater than 6.5% but ≤7.0%, the corresponding temperature of 175°C is selected as the optimal construction temperature; when the modifier dosage is greater than 7.0% but ≤8.0%, the corresponding temperature of 195°C is selected as the optimal construction temperature; when the modifier dosage is greater than 8.0% but ≤8.5%, the corresponding temperature of 205°C is selected as the optimal construction temperature. In the actual production process, the test temperature can be further refined in step (2) according to the actual accuracy requirements (for example, testing once every 2°C from 80°C to 210°C) to obtain more accurate optimal construction temperature values ​​under different modifier dosages. In this embodiment, considering the length of the article and actual needs, only four temperatures are selected for testing, which can determine the asphalt construction temperature within a certain dosage range. If the test temperature is further refined, a more accurate optimal construction temperature can be obtained.

[0044] Embodiment 2:

[0045] The method of determining the optimal construction temperature of modified asphalt under different modifier dosages in this embodiment comprises the following steps:

[0046] (1) The preparation method of the modified asphalt sample of this embodiment is basically the same as that of the embodiment, the only difference being that a linear SBS modifier and 0.15% sulfur are added to the base asphalt in this embodiment.

[0047] (2) The viscosity of the modified asphalt samples was tested at different temperatures. The test temperature was 80°C-210°C. The appropriate rotor model was selected according to the specific test temperature and the type of asphalt sample. The torque reading was controlled within the range of 10%-98%. Some test data are shown in Table 2 below:

[0048] Table 2: Relationship between SBS content in S / SBS ​​modified asphalt and modified asphalt viscosity

[0049]

[0050] (3) At a specific temperature, a curve is drawn with the modifier dosage as the horizontal axis and the viscosity of the modified asphalt sample as the vertical axis; by taking the first derivative of the viscosity curve, the mutation point O where the viscosity of the modified asphalt changes with the modifier dosage is obtained; by taking the derivative of the viscosity curve, the viscosity derivative curve is analyzed. For ease of understanding, Δd is used to represent the viscosity Δη / ΔSBS dosage after differentiation, and the viscosity derivative curve at different temperatures with the SBS dosage is obtained. By taking the first-order derivative of the curve, it is determined that the SBS dosage values ​​corresponding to the mutation points at 135℃, 175℃, 190℃ and 205℃ are 4.0%, 5.0%, 6.0% and 6.5%, respectively; the first derivative graphs of the viscosity of the modified asphalt with the modifier dosage at 135℃, 175℃, 190℃ and 205℃ are shown in the figure below: Figure 5-8 As shown, it shows that at the corresponding modifier dosage at this mutation point, the corresponding temperature can be used as the optimal construction temperature of asphalt. At the same time, at 135°C, when the SBS dosage is about 5%, the viscosity derivative also has a small mutation point O, which corresponds to the transition point of the SBS phase in asphalt.

[0051] (4) According to steps (1) to (3), the relationship between the SBS modifier dosage and the optimal construction temperature is obtained, that is, the minimum value of the SBS dosage corresponding to each mutation point is taken as the starting point, that is, when the modifier dosage is ≤4.0%, the corresponding temperature of 135°C is selected as the optimal construction temperature; when the modifier dosage is greater than 4.0% but ≤5.0%, the corresponding temperature of 175°C is selected as the optimal construction temperature; when the modifier dosage is greater than 5% but ≤6.0%, the corresponding temperature of 195°C is selected as the optimal construction temperature; when the modifier dosage is greater than 6.0% but ≤6.5%, the corresponding temperature of 205°C is selected as the optimal construction temperature.

[0052] Sulfur is added to SBS modified asphalt, SBS will cross-link with sulfur in the process of forming a network structure, forming a vulcanized SBS network structure, reducing the temperature sensitivity of SBS modified asphalt, and improving the high temperature performance and compatibility of SBS modified asphalt. In the modification process, the polystyrene in SBS is surrounded by polybutadiene, and polystyrene and polybutadiene are interconnected and constructed into a network structure. After adding sulfur, the polybutadiene block in SBS produces a chemical cross-linking domain and forms a more complex macromolecule. The cross-linked network structure formed at this time is formed under the combined action of physical reaction and chemical reaction, and the vulcanization cross-linking is formed. A more stable structure. Sulfur reacts chemically with SBS modified asphalt, which will affect the performance of SBS modified asphalt, so that the viscosity mutation point value of modified asphalt appears 0%~2% in advance, but does not affect the overall trend of its viscosity change and fluorescence change, so the method of the present embodiment is also applicable to the polymer modified asphalt adding stabilizers such as sulfur, which shows the universality of the method of the present invention for different modifiers.

[0053] Embodiment 3:

[0054] (1) The preparation method of the modified asphalt sample of this embodiment is basically the same as that of the embodiment, the only difference being that in this embodiment, a star-shaped SBS modifier and 3% of nano-organic montmorillonite (OMMT) are added to the base asphalt.

[0055] (2) The viscosity of the modified asphalt samples was tested at different temperatures. The test temperature was 80°C-210°C. The appropriate rotor model was selected according to the specific test temperature and the type of asphalt sample. The torque reading was controlled within the range of 10%-98%. Some test data are shown in Table 3 below:

[0056] Table 3: Relationship between SBS content in OMMT / SBS modified asphalt and modified asphalt viscosity

[0057]

[0058] (3) Plot a curve with the modifier dosage as the horizontal axis and the viscosity of the modified asphalt sample as the vertical axis; by taking a derivative of the viscosity curve, obtain the mutation point where the viscosity of the modified asphalt changes with the modifier dosage (in this embodiment, when the temperature is 190°C and 205°C, it is found that the Δd mutation point is no longer obvious, indicating that the asphalt construction temperature is below 190°C, so only the curves at 135°C and 175°C are analyzed); by taking the derivative of the viscosity curve and analyzing the viscosity derivative curve, obtain the change curve of the viscosity derivative with the SBS dosage at different temperatures, 135°C, 175°C and 190°C, respectively. Figure 9-11 As shown, the mutation point O at 135℃ and 175℃ is determined by the first-order derivative of the curve. The SBS dosage values ​​corresponding to the mutation point O are 5.0% and 6.0%, respectively; this indicates that when the modifier dosage is not higher than the dosage corresponding to the mutation point O, this temperature can be used as the construction temperature of asphalt.

[0059] (4) According to steps (1) to (3), the relationship between the SBS modifier dosage and the optimal construction temperature is obtained, that is, the minimum value of the SBS dosage corresponding to each mutation point is taken as the starting point, that is, when the modifier dosage is ≤5.0%, the corresponding temperature of 135°C is selected as the optimal construction temperature; when the modifier dosage is greater than 5.0% but ≤6.0%, the corresponding temperature of 175°C is selected as the optimal construction temperature.

[0060] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for determining the optimal construction temperature of modified asphalt under different modifier dosages, characterized in that: The following steps are involved: S1. Prepare modified asphalt samples with different modifier dosages and test the viscosity of the samples at different temperatures Tn, where n is a positive integer; S2. At temperature T1, a curve is drawn with the modifier dosage as the horizontal axis and the viscosity of the modified asphalt sample as the vertical axis, and the mutation point where the viscosity changes with the modifier dosage is determined based on the curve. T1 ; S3, mutation point O T1 The corresponding horizontal axis value is the modifier dosage C T1 , temperature T1 is the mutation point O T1 Corresponding modifier dosage C T1 The best construction temperature for modified asphalt is: S4. Test to obtain the mutation point O at different temperatures Tn Tn , get the modifier dosage C Tn The relationship between the modified asphalt and the optimal construction temperature Tn is determined according to the modifier dosage of the modified asphalt during actual construction.

2. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to claim 1, characterized in that: The mutation point O in S2 T1 And the mutation point O described in S3 Tn Determined by: The curve is differentiated once to obtain a derivative curve of viscosity and dosage; when the slope of the derivative curve changes suddenly with the increase of the modifier dosage, the corresponding modifier dosage is counted as the mutation point.

3. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to claim 1, characterized in that: In step S1, the dosage of the modifier varies linearly between 1% and 10%.

4. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to claim 1, characterized in that: In step S1, the detection temperature range of the sample is 80°C-210°C.

5. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to claim 1, characterized in that: In step S1, when detecting the viscosity, the torque range of the viscometer is controlled to be 10%-98%.

6. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to any one of claims 1 to 5, characterized in that: The modifier is styrene-butadiene-styrene or a mixture containing styrene-butadiene-styrene.

7. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to claim 6, characterized in that: According to methods S1 to S4, the relationship between the modifier dosage and the optimal construction temperature in modified asphalt with different types of modifiers is tested, and a database of optimal construction temperatures for different modifiers is constructed; the optimal construction temperature of the modified asphalt is determined according to the modifier type and modifier dosage of the modified asphalt during actual construction.

8. The method for determining the optimal construction temperature of modified asphalt under different modifier dosages according to any one of claims 1 to 5, characterized in that: When the mutation point cannot be determined according to the curve of S2, the viscosity test temperature of the modified asphalt sample is lowered until the mutation point is determined.

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