A method for reducing the viscosity of high-viscosity waste rubber powder modified asphalt using low-dosage cycloalkane oil

Abstract

The present invention relates to the technical field of modified asphalt pavement materials, and specifically proposes a new method for reducing the viscosity of high-viscosity waste rubber powder modified asphalt using low-dosage cycloalkane oil. After physically stirring the waste rubber powder with a small amount of cycloalkane oil, the mixture is placed at a certain temperature for swelling treatment to obtain pre-swollen waste rubber powder; the pre-swollen waste rubber powder is mechanically sheared and mixed with matrix asphalt to prepare reduced-viscosity waste rubber powder modified asphalt. Compared with traditional viscosity reduction methods, the method of the present invention significantly reduces the viscosity of high-viscosity waste rubber powder modified asphalt, while maintaining good high and low temperature deformation resistance, anti-aging performance and long-term fatigue life. This viscosity reduction method not only provides an effective solution for the reuse of waste rubber, but also solves the difficulties faced by high-viscosity waste rubber powder modified asphalt during the construction process, and promotes its application in engineering.

Description

Technical Field

[0001] The invention relates to the technical field of modified asphalt pavement materials, and specifically provides a method for reducing the viscosity of high-viscosity waste rubber powder modified asphalt by utilizing low-dosage cycloalkane oil. Background Art

[0002] Waste rubber powder is made from the crushing of waste tires. Its application in the preparation of modified asphalt not only effectively solves the disposal problem of waste tires, but also significantly improves the low-temperature crack resistance of asphalt. Compared with traditional asphalt, its rheological properties are better. However, there are still some unresolved issues:

[0003] First, although high-content waste rubber powder modified asphalt increases the viscosity, it reduces the paving and compaction performance of the mixture; low content does not meet the requirements of high-viscosity asphalt pavement.

[0004] Secondly, traditional viscosity reduction methods fail to effectively prevent the thermal decomposition of rubber powder and asphalt in waste rubber powder modified asphalt, thereby reducing the durability of the modified asphalt.

[0005] In summary, the traditional viscosity reduction methods for high-viscosity waste rubber powder modified asphalt have the following problems: the viscosity reduction degree is too large to meet the high viscosity requirements of modified asphalt, the high and low temperature rheological properties are uneven, the fatigue resistance is poor, the anti-aging performance is poor, and it is not economical, which is not conducive to the promotion and application of high-viscosity waste rubber powder modified asphalt. Therefore, these problems highlight the urgent need to develop new viscosity reduction technologies to improve the long-term performance and sustainability of waste rubber powder modified asphalt. Summary of the invention

[0006] The present invention proposes a new method for reducing the viscosity of high-viscosity waste rubber powder modified asphalt using low-dosage cycloalkane oil to solve the problems in the above-mentioned background technology.

[0007] A new method for reducing the viscosity of waste rubber powder modified asphalt using low-dosage cycloalkane oil, comprising the following steps:

[0008] Step (1) mixing the cycloalkane oil and the waste rubber powder evenly by physical stirring to obtain a mixture;

[0009] Step (2) heating the mixture at a certain temperature for a period of time to allow the waste rubber powder to fully swell in the cycloparaffin oil and stabilize its volume, thereby obtaining pre-swollen waste rubber powder;

[0010] Step (3) mechanically mixing the pre-swollen waste rubber powder with the matrix asphalt;

[0011] The mass of the cycloalkane oil accounts for 1%-3% of the mass of the base asphalt.

[0012] Furthermore, the mass of the waste rubber powder accounts for 15%-30% of the mass of the base asphalt, preferably 20%.

[0013] Furthermore, in the step (2), the swelling temperature is 60-70° C., and the swelling time is 6-8 hours.

[0014] Furthermore, the mechanical mixing method in step (3) is: mixing using a shearing machine, the shearing speed is set to 5000 rpm, and shearing is performed at 170°C for 40 minutes. In the first 10 minutes, the waste rubber powder that has swelled to a certain extent is added to the base asphalt three times, and then shearing is continued for 30 minutes to ensure that the waste rubber powder is evenly distributed in the modified asphalt.

[0015] Furthermore, the base asphalt is 70# base asphalt.

[0016] Furthermore, the waste rubber powder is waste rubber powder of non-single particle size, and has a certain particle gradation.

[0017] Furthermore, the particle size distribution of the waste rubber powder is as follows:

[0018]

[0019] Compared with the prior art, the advantages and beneficial effects of the present invention are:

[0020] (1) The traditional viscosity reduction process is to add oil directly to the waste rubber powder modified asphalt to reduce the viscosity (the waste rubber powder will swell in the later stage), and the performance of the waste rubber powder modified asphalt after viscosity reduction cannot be guaranteed. The novel viscosity reduction method provided by the present invention is to mix oil with waste rubber powder first, swell them, and then use them for asphalt modification and viscosity reduction, so as to ensure the uniformity of the performance of the modified asphalt.

[0021] (2) Unlike conventional waste rubber powder modified asphalt, which uses waste rubber powder of a single particle size, the waste rubber powder in the present invention is graded, just like aggregate particles, with different particle sizes. Conventional waste rubber powder is only used for modification in modified asphalt, while the waste rubber powder in the present invention is not only modified, but also acts as aggregate, plays a filling role, is more uniform, and provides better performance for the modified asphalt.

[0022] (3) The novel viscosity reduction method provided by the present invention can effectively reduce the viscosity of high-viscosity waste rubber powder modified asphalt by using a low amount of cycloalkane oil, thereby preventing the use of a high amount of cycloalkane oil in the traditional viscosity reduction method, which leads to an increase in the viscosity reduction cost of the waste rubber powder modified asphalt and a decrease in high-temperature performance, thereby improving its paving and workability; the method balances the rheological properties of the waste rubber powder modified asphalt and extends its fatigue life; at the same time, the new viscosity reduction method enhances the anti-aging performance of the modified asphalt, overcoming the limitations of the traditional viscosity reduction method in the production of waste rubber powder modified asphalt.

[0023] (4) The use of traditional high-volume oil viscosity reduction methods or waste rubber powder of a single particle size will increase the cost of preparing and reducing the viscosity of waste rubber powder modified asphalt, and the high and low temperature deformation resistance, fatigue resistance and aging resistance of the waste rubber powder modified asphalt after viscosity reduction are poor. The present invention simultaneously utilizes low-volume cycloalkane oil, pre-swelling viscosity reduction, and waste rubber powder of different particle sizes, which will reduce the cost of preparing and reducing the viscosity of waste rubber powder modified asphalt, and the high and low temperature deformation resistance, fatigue resistance and aging resistance of the waste rubber powder modified asphalt after viscosity reduction are greatly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a schematic diagram of the viscosity reduction preparation method of pre-swollen waste rubber powder modified asphalt of the present invention and the traditional direct viscosity reduction method.

[0025] Figure 2 This is the particle gradation curve of the waste rubber powder in the waste rubber powder modified asphalt prepared in Examples 1-4.

[0026] Figure 3 It is the viscoelastic ratio of the waste rubber powder modified asphalt produced by the new viscosity reduction process in the example and the traditional direct viscosity reduction process.

[0027] Figure 4 The aging performance of the new process of Example 4 and the traditional process of Example 2 in the viscosity reduction of waste rubber powder modified asphalt is compared.

[0028] Figure 5 The infrared spectra of the waste rubber powder modified asphalt and raw materials prepared in Examples 1-4. DETAILED DESCRIPTION

[0029] The technical solution of the present invention is described in more detail below through embodiments and accompanying drawings.

[0030] In the following examples, the total mass of the waste rubber powder modified asphalt after viscosity reduction was 500 g.

[0031] The original gradation data of the waste rubber powder particles used in the following examples are shown in Table 1. The 70# matrix asphalt is provided by Shanxi Yutong Road Materials Co., Ltd., and its physical performance indicators are shown in Table 2; the cycloalkane oil used is KN-4010 of Jinan Luying Chemical Co., Ltd.

[0032] Table 1 Original gradation data of waste rubber powder particles

[0033]

[0034] Table 2 Physical properties of 70# base asphalt

[0035]

[0036] All indicators are tested according to common sense in the industry, and the aging quality changes of the film are carried out in accordance with the standard: ASTMD1754 / D1754M-09 (2014).

[0037] Example 1

[0038] A conventional method for preparing waste rubber powder modified asphalt with reduced viscosity comprises the following steps:

[0039] Step (1) weighed 0g cycloalkane oil, 83.3g waste rubber powder and 416.7g 70# matrix asphalt;

[0040] Step (2) 83.3g of waste rubber powder was placed in an oven at 25°C for 8 hours of heat treatment;

[0041] Step (3). Shear the 83.3g waste rubber powder after heat preservation into 416.7g of 70# base asphalt: Use a shearing machine to shear at a speed of 5000rpm at 170℃ for 40 minutes, add the waste rubber powder to the asphalt three times in the first 10 minutes, and shear for the last 30 minutes to ensure that it is evenly distributed in the asphalt. Finally, a waste rubber powder modified asphalt with no swelling and 0% cycloparaffin oil content is prepared, abbreviated as NSCRMA0%.

[0042] Example 2

[0043] A conventional method for preparing waste rubber powder modified asphalt with reduced viscosity comprises the following steps:

[0044] Step (1) weighed 12.2g cycloparaffin oil, 81.3g waste rubber powder and 406.5g 70# base asphalt;

[0045] Step (2) 12.2g of cycloalkane oil and 81.3g of waste rubber powder were placed in an oven at 65°C for 8 hours of thermal expansion treatment;

[0046] Step (3). Shear 81.3 g of waste rubber powder and 12.2 g of cycloparaffin oil after heat expansion into 406.5 g of 70# base asphalt: use a shearing machine to shear at a speed of 5000 rpm at 170°C for 40 minutes. In the first 10 minutes, add the waste rubber powder and cycloparaffin oil to the base asphalt three times, and shear for the last 30 minutes to ensure that the two are evenly distributed in the asphalt. Finally, prepare unswollen waste rubber powder modified asphalt with a cycloparaffin oil content of 3%, abbreviated as NSCRMA3%.

[0047] Example 3

[0048] A method for preparing asphalt viscosity reduction by pre-swelling waste rubber powder modified asphalt comprises the following steps:

[0049] Step (1) weighed 0g of cycloparaffin oil, 83.3g of waste rubber powder and 416.7g of 70# matrix asphalt;

[0050] Step (2) 83.3g of waste rubber powder was placed in an oven at 65°C for 8 hours of thermal swelling treatment;

[0051] Step (3). Shear the heat-swollen waste rubber powder into 416.7g of 70# matrix asphalt: use a shearing machine with a shearing speed of 5000rpm and shear for 40 minutes at 170°C. In the first 10 minutes, the waste rubber powder is evenly added to the matrix asphalt three times, and the shearing for the last 30 minutes is to ensure that the waste rubber powder is evenly distributed in the asphalt. Finally, a pre-swollen waste rubber powder modified asphalt with a cycloparaffin oil content of 0% is prepared, abbreviated as PSCRMA0%.

[0052] Example 4

[0053] A method for preparing asphalt with reduced viscosity by pre-swelling waste rubber powder modified asphalt comprises the following steps:

[0054] Step (1) weighed 12.2g cycloparaffin oil, 81.3g waste rubber powder and 406.5g 70# base asphalt;

[0055] Step (2) 12.2g of cycloalkane oil was mixed with 81.3g of waste rubber powder and placed in an oven at 65°C for 8 hours of pre-swelling treatment;

[0056] Step (3). Shear the pre-swollen cycloalkane oil and waste rubber powder mixture into 406.5g of 70# base asphalt: Use a shearing machine to shear at a speed of 5000rpm at 170°C for 40 minutes. Within the first 10 minutes, the pre-swollen mixture is added to the asphalt three times. The shearing for the last 30 minutes is to ensure that the waste rubber powder is evenly distributed in the asphalt. The final pre-swollen, cycloalkane oil content of 3% waste rubber powder modified asphalt is abbreviated as PSCRMA3%.

[0057] The rotational viscosity of the waste rubber powder modified asphalt prepared in Examples 1 to 4 is shown in Table 3.

[0058] Table 3 Rotational viscosity of waste rubber powder modified asphalt at 135℃

[0059]

[0060] Comparison Table 3 shows that low dosage of cycloalkane oil significantly reduces the viscosity of high viscosity waste rubber powder modified asphalt. When the dosage of cycloalkane oil is 3%, according to ASTM D 4402 standard, the rotational viscosity of high viscosity waste rubber powder modified asphalt at 135°C does not exceed 3000mPa·s, which meets the construction requirements. Compared with the waste rubber powder modified asphalt (NSCRMA0% and NSCRMA3%) prepared by traditional construction technology, the modified asphalt (PSCRMA3%) prepared by the new pre-swelling viscosity reduction process maintains a higher viscosity, which can meet the demand for high viscosity modified asphalt in pavement engineering, enhance the bonding strength between asphalt and aggregate, reduce the risk of separation, and improve the deformation resistance of asphalt.

[0061] The comparison of the viscosity reduction method of the new process of pre-swelling of waste rubber powder modified asphalt and the traditional direct viscosity reduction method in high temperature rheological properties, low temperature rheological properties and fatigue life is shown in Table 4.

[0062] Table 4 High temperature rutting resistance, low temperature cracking resistance and medium temperature fatigue resistance of waste rubber powder modified asphalt

[0063]

[0064] According to Table 4, under the same cycloalkane oil content, the rutting factor of the waste rubber powder modified asphalt after viscosity reduction by the new pre-swelling process is higher than that of the waste rubber powder modified asphalt produced by the traditional direct viscosity reduction method, which indicates that the modified asphalt produced by the new method has stronger resistance to high temperature deformation. In addition, the waste rubber powder modified asphalt reduced by the new pre-swelling process is also significantly better than the traditional method in low temperature crack resistance and fatigue life.

[0065] The low dosage of cycloparaffin oil causes the waste rubber powder to not fully expand, so that it is partially used as a modifier and partially as an aggregate filler. There are differences in the particle size distribution of the waste rubber powder in the waste rubber powder modified asphalt produced by the new pre-swelling process and the traditional direct viscosity reduction process (the waste rubber powder in the waste rubber powder modified asphalt is separated by conventional methods and then relevant tests are carried out). For example, Figure 2 shown.

[0066] The ideal grading curve should present a smooth S-shape. In terms of particle size distribution, the grading curves of NSCRMA0% and PSCRMA0% show that the performance of PSCRMA0% is better than that of NSCRMA0%, which is due to its more uniform distribution of large particles, thereby improving the density and strength of CRMA. In addition, by comparing the particle grading curves of PSCRMA3% and NSCRMA3%, it is found that the grading performance of PSCRMA3% is better at multiple control particle size points. The overall analysis shows that the grading effect of PSCRMA0% is the best, followed by NSCRMA0% and PSCRMA3%, while the particle grading effect of NSCRMA3% is the worst. Therefore, under the same low NO dosage, the viscosity reduction method of the new pre-swelling process of the present invention makes the gradation of waste rubber powder in waste rubber powder modified asphalt better than the gradation of waste rubber powder treated by the traditional direct viscosity reduction method, and can provide better performance.

[0067] Comparison of viscoelasticity between waste rubber powder modified asphalt produced by pre-swelling new process and waste rubber powder modified asphalt produced by traditional direct viscosity reduction at 25℃ Figure 3 The experiment used a dynamic shear rheometer to conduct a frequency sweep experiment to obtain the viscoelastic ratio of the modified asphalt.

[0068] The viscoelasticity of the waste rubber powder modified asphalt produced by the new pre-swelling process is relatively small, indicating that it has greater elasticity and better deformation resistance than the waste rubber powder modified asphalt produced by the traditional process.

[0069] The optical microscope experiment observed the new pre-swelling viscosity reduction process of Example 4 and the traditional direct viscosity reduction process of Example 2 to prepare waste rubber powder modified asphalt. Figure 4 In this new process, the aperture formed by cycloparaffin oil around the waste rubber powder is larger and more obvious, indicating that the new process allows more cycloparaffin oil to cover the surface of the waste rubber powder, thereby reducing its aging during use and enhancing the durability of the modified asphalt.

[0070] In order to more intuitively express the anti-pyrolysis ability of each sample, the infrared spectra of the waste rubber powder modified asphalt and raw materials prepared in Examples 1-4 were tested, as shown in FIG. Figure 5 As shown, 3400cm -1 The hydroxyl group (-OH) is at 1770cm -1 and 1720cm -1 The carbonyl group (C=O) is at 1060cm -1 and 1033cm -1 It is a sulfoxide group (S=O); by comparison, the traditional process will greatly weaken the waste rubber powder and matrix asphalt in the above functional groups, increase the pyrolysis of raw materials, and reduce the durability of the materials. The new viscosity reduction method prevents this pyrolysis behavior and increases the durability of the materials.

Claims

1. A method for reducing the viscosity of waste rubber powder modified asphalt using low-dosage cycloparaffin oil, comprising the following steps: Step (1) uniformly mixing cycloalkane oil and waste rubber powder to obtain a mixture; Step (2) heating the mixture at 60-70° C. for 6-8 hours to allow the waste rubber powder to fully swell in the cycloalkane oil and stabilize the volume, thereby obtaining pre-swollen waste rubber powder; Step (3) mechanically mixing the pre-swollen waste rubber powder with the matrix asphalt; The mass of the cycloparaffin oil accounts for 1%-3% of the mass of the base asphalt; the mass of the waste rubber powder accounts for 15%-30% of the mass of the base asphalt; the waste rubber powder is waste rubber powder of non-single particle size, which has a certain particle gradation, and the particle gradation is as follows: The specific method of mechanical mixing is: mixing with a shearing machine, the shearing speed is set to 5000rpm, and shearing is performed at 170°C for 40 minutes. In the first 10 minutes, the pre-swollen waste rubber powder is added to the base asphalt three times, and then shearing is continued for 30 minutes to ensure that the waste rubber powder is evenly distributed in the modified asphalt.

Images