Modified asphalt and methods for its production

Abstract

Modified asphalt comprising, by weight, the following raw material components: 70-90 parts of base asphalt and 10-18 parts of a modifier; wherein the modifier is a mixture of SBS, calcium oxide and n-butyl acrylate and wherein the modifier comprises 6 - 9 parts by weight of SBS, 3 - 6 parts by weight of calcium oxide and 1 - 3 parts by weight of n-butyl acrylate and wherein the modified asphalt contains an emulsifier.

Description

FIELD OF TECHNOLOGY

[0001] The invention relates to the field of asphalt technology, in particular modified asphalt and a process for its production. BACKGROUND

[0002] Over the past decade, highway construction in China has developed rapidly. Since the founding of the People's Republic of China, the number of kilometers of roads has grown from tens of thousands of kilometers to the world's largest road network. Compared with cement pavement, asphalt pavement has the advantages of higher driving comfort, stable and low noise, easier maintenance, and more. Asphalt is the material of choice for highway construction in various countries. Expressways carry high traffic volumes, high speeds, and high loads, so the pavement has higher requirements: good durability, high load-bearing capacity, a smooth surface, and good skid resistance.In recent years, China's economy has developed rapidly, the number of privately owned vehicles has increased rapidly, and traffic on expressways is increasing year after year, bringing new challenges to road use at all levels, especially the increasingly stringent requirements for the performance of asphalt pavement on well-developed highways.

[0003] SBS-modified asphalt means that a certain amount of SBS modifier is added to the base asphalt. At a certain temperature, the SBS modifier can be evenly distributed in the base asphalt through special manufacturing processes such as shearing and stirring, thus achieving a mixed state and improving the asphalt's performance through the physical structure of SBS in the asphalt. Rubber powder-modified asphalt refers to adding a certain amount of fine rubber powder produced from scrap tires through special processing technology to the asphalt, processing and treatment through mechanical processes such as shearing and mixing at high temperatures, and finally producing an asphalt rubber powder binder with improved properties during swelling and other steps.Currently, SBS-modified asphalt is widely used in road construction in China and is widely accepted by engineers and technical personnel. As a new type of modified asphalt, rubber powder-modified asphalt is gradually gaining acceptance. It is a type of asphalt with great development potential and ample room for further development.

[0004] Conventional SBS asphalt has several performance disadvantages, such as poor adhesion, low elongation, high wax content, and high temperature sensitivity. Therefore, it is difficult to use on well-developed expressways. At the same time, due to the rapidly growing traffic volume driven by economic growth, the significantly increased vehicle load, and the large temperature differences between north and south, winter and summer in China, higher requirements for asphalt pavement quality are imposed.

[0005] EP 0 599 462 A1, US 2004 / 0030008 A1, CN 113969064 A, CN 106751949 A and CN 103773023 A are cited as prior art.

[0006] Against this background, the present invention is presented. DEMOLITION

[0007] The invention relates to a modified asphalt comprising the following raw material components by weight: 70 - 90 parts of base asphalt and 10 - 18 parts of a modifier; The modifier is a mixture of SBS, calcium oxide and n-butyl acrylate.

[0008] According to the modified asphalt described above, the modifier comprises 6-9 parts by weight of SBS, 3-6 parts by weight of calcium oxide, and 1-3 parts by weight of n-butyl acrylate. Furthermore, the modified asphalt contains an emulsifier.

[0009] Alternatively, according to the modified asphalt described above, the modifier comprises 7-8 parts by weight of SBS, 4-5 parts by weight of calcium oxide and 2 parts by weight of n-butyl acrylate.

[0010] Alternatively, according to the modified asphalt described above, the base asphalt is an asphalt No. 90 Class A.

[0011] Alternatively, according to the modified asphalt described above, it contains at least one of a crosslinker, compatibilizer and stabilizer.

[0012] Alternatively, according to the modified asphalt described above, the emulsifier is 1-5 parts by weight or 2, 3, 4 parts by weight of JY-R2 emulsifier.

[0013] Alternatively, according to the modified asphalt described above, the crosslinker is 1-3 parts by weight or 2 parts by weight of crystalline sulfur.

[0014] Alternatively, according to the modified asphalt described above, the compatibilizer is 1-3 parts by weight or 2 parts by weight of naphthenic oil.

[0015] Alternatively, according to the modified asphalt described above, the stabilizer is 5-10 parts by weight or 6, 7, 8, 9 parts by weight of asbestos ash.

[0016] A further aspect of the invention relates to a process for producing modified asphalt as described above, comprising: Heating and grinding components other than base asphalt to obtain a mixture; Slowly adding the mixture to the base asphalt, which is heated to melt and stir evenly, and then naturally cooling after shearing by the emulsifier.

[0017] Alternatively, according to the manufacturing method described above, the shearing speed is 17000 rpm - 20000 rpm and the shearing time is 20 min - 40 min.

[0018] Advantageous effects: The invention utilizes a mixed modifier containing SBS, calcium oxide, and n-butyl acrylate for modification. n-butyl acrylate can interact with SBS and calcium oxide to increase the overall strength of asphalt. The addition of calcium oxide and n-butyl acrylate can also significantly improve the weather resistance of asphalt. Optimizing the compatibility of the raw materials makes production simple, eliminating the need for multiple additions of modifiers, stabilizers, and other components. DETAILED DESCRIPTION

[0019] The embodiment of the invention will be described in detail below in conjunction with the embodiment. It should be understood that these embodiments are for illustrative purposes only, not to limit the scope of the invention. For experimental procedures without specific conditions specified in the following embodiments, the specifications specified in the invention, according to the experimental manual or conventional conditions known in the art, or according to the conditions recommended by the manufacturer, should prevail.

[0020] In the following specific embodiments, the measurement parameters related to raw material components may exhibit slight deviations within the weight accuracy ranges unless otherwise noted. Including the temperature and time parameters, an acceptable deviation is permitted, resulting from instrument-based test accuracy or accuracy in operation. Example 1 1) Swelling: Heating of 70 kg of base asphalt No. 90 Class A to melt the base asphalt; 2) Heating 6 kg of SBS, 3 kg of calcium oxide, 3 kg of n-butyl acrylate, 1 kg of JY-R2 emulsifier, 3 kg of crystalline sulfur, 1 kg of naphthenic oil and 10 kg of asbestos ash to 140 °C - 160 °C (mainly conducive to the mixing of n-butyl acrylate), grinding and mixing to obtain the mixture; 3) Add the above mixture to the molten asphalt in several portions while stirring. Ensure no bubbles form during mixing and add additional defoamer if necessary. 4) In the molten state (approx. 180 °C - 210 °C), a single-stage, high-gravity emulsifying machine is used for high-speed shearing and stirring. The shear speed is 17,000 rpm and the shear time is 40 minutes. 5) Natural cooling. Example 2 1) Swelling: Heating of 90 kg of base asphalt No. 90 Class A to melt the base asphalt; 2) Heating 9 kg of SBS, 6 kg of calcium oxide, 1 kg of n-butyl acrylate, 5 kg of JY-R2 emulsifier, 1 kg of crystalline sulfur, 3 kg of naphthenic oil and 5 kg of asbestos ash to 140 °C - 160 °C (mainly conducive to the mixing of n-butyl acrylate), grinding and mixing to obtain the mixture; 3) Add the above mixture to the molten asphalt in several portions while stirring. Ensure no bubbles form during mixing and add additional defoamer if necessary. 4) In the molten state (approx. 180 °C - 210 °C), a single-stage, high-gravity emulsifying machine is used for high-speed shearing and stirring. The shear speed is 20,000 rpm and the shear time is 20 minutes. 5) Natural cooling. Example 3 1) Swelling: Heating of 80 kg of base asphalt No. 90 Class A to melt the base asphalt; 2) Heating 7 kg of SBS, 5 kg of calcium oxide, 2 kg of n-butyl acrylate, 3 kg of JY-R2 emulsifier, 2 kg of crystalline sulfur, 2 kg of naphthenic oil and 7 kg of asbestos ash to 150 °C (mainly conducive to the mixing of n-butyl acrylate), grinding and mixing to obtain the mixture; 3) Add the above mixture to the molten asphalt in several portions while stirring. Ensure no bubbles form during mixing and add additional defoamer if necessary. 4) In the molten state (approx. 180 °C - 210 °C), a single-stage, high-gravity emulsifying machine is used for high-speed shearing and stirring. The shear speed is 20,000 rpm and the shear time is 20 minutes. 5) Natural cooling. Comparison example 1.

[0021] Based on Example 3, n-butyl acrylate was replaced by an equal amount of calcium oxide. Comparison example 2.

[0022] Based on Example 3, calcium oxide was replaced by an equal amount of n-butyl acrylate. Comparison example 3.

[0023] Based on Example 3, calcium oxide and n-butyl acrylate were replaced by an equal amount of SBS. Experimental example

[0024] Basic indices of modified asphalt (tested according to standard JTG F40-2004 and test method JTJ052-2000): Table 1 Basic indices group Tested Test value Default value Example 3 Needle penetration 67 IC: 60-80 25°C (10-1 mm:100 g) 5 s ID: 30-60 Ductility 33 IC50: ≥30 5°C, 5 cm / min (cm) ID: ≥20 Softening point 68 IC: ≥55 T&B °C ID: ≥60 Comparison example 1 Needle penetration 63 IC: 60-80 25°C (10-1 mm:100 g) 5 s ID: 30-60 Ductility 26 IC50: ≥30 5°C, 5 cm / min (cm) ID: ≥20 Softening point 67 IC: ≥55 T&B °C ID: ≥60 Comparison example 2 Needle penetration 67 IC: 60-80 25°C (10-1 mm:100 g) 5 s ID: 30-60 Ductility 32 IC50: ≥30 5°C, 5 cm / min (cm) ID: ≥20 Softening point 63 IC: ≥55 T&B °C ID: ≥60 Comparison example 3 Needle penetration 61 IC: 60-80 25°C (10-1 mm:100 g) 5 s ID: 30-60 Ductility 24 IC50: ≥30 5°C, 5 cm / min (cm) ID: ≥20 Softening point 65 IC: ≥55 T&B °C ID: ≥60

[0025] It can be seen that the modified asphalt produced by the invention meets the national standard and achieves good performance. Removing n-butyl acrylate obviously affects the ductility of asphalt.

[0026] The results of the low-temperature bending test are shown in Table 2, and the size of the test piece is 40 mm × 40 mm × 200 mm. Table 2 Results of the low-temperature bending test Example No. Cross-sectional height (mm) Test specimen span (mm) Deflection in the center (µm) Average value of failure due to stress (µg) Example 3 40,0 200 603,6 3321,6 Comparison example 1 459,4 2531,1 Comparison example 2 479,9 2757,2 Comparison example 3 448,7 2489,7

[0027] The low-temperature properties of asphalt are important factors influencing its low-temperature fracture behavior. The low-temperature flexural test shows that both n-butyl acrylate and calcium oxide can significantly influence the low-temperature properties of asphalt. Assessment of stability at high temperatures

[0028] Rutting test: The rut plate size is 300 mm × 300 mm × 100 mm, and the test temperature is 60°C. The deformation at 45 min and 60 min is observed, and the number of revolutions of the test wheel at 1 mm deformation is calculated as the dynamic stability. The results are shown in Table 3. Table 3 Results of the rutting test Example No. Rut depth (mm) at the following time (min) Average value of dynamic stability (number / mm) Technical requirements (number / mm) 45 60 Example 3 0,839 1,214 6715 Comparison example 1 2,985 3,453 4110 Comparison example 2 2,537 2,698 5316 Comparison example 3 3,036 3,513 4081

[0029] The stability after rutting testing of the modified asphalt provided by the invention is higher than required by the current specification. Compared to the example, the performance of Comparative Examples 1-3 is significantly lower.

[0030] In combination with the above test results, it is shown that the modified asphalt provided by the invention has good weather resistance.

[0031] The above embodiments merely illustrate various embodiments of the invention, and the description is more specific and detailed. However, it should be understood that the scope of the invention is not limited by this. It should be obvious to those skilled in the art that various modifications and improvements are possible without departing from the concept of the invention, which still fall within the scope of the invention. Therefore, the scope of the patent is determined by the following claims, and the specifications and accompanying drawings may be used to explain the contents of the claims.

Claims

[1] Modified asphalt comprising by weight the following raw material components: 70 - 90 parts of base asphalt and 10 - 18 parts of a modifier; wherein the modifier is a mixture of SBS, calcium oxide and n-butyl acrylate and wherein the modifier comprises 6-9 parts by weight of SBS, 3-6 parts by weight of calcium oxide and 1-3 parts by weight of n-butyl acrylate and wherein the modified asphalt contains an emulsifier. [2] Modified asphalt according to claim 1, wherein the base asphalt is Asphalt No. 90 Class A. [3] Modified asphalt according to any one of claims 1-2, which contains at least one of a crosslinker, compatibilizer and stabilizer. [4] Modified asphalt according to claim 3, wherein the crosslinker is 1-3 parts by weight of crystalline sulfur. [5] Modified asphalt according to claim 3, wherein the compatibilizer is 1 ∼ 3 parts by weight of naphthenic oil. [6] Modified asphalt according to claim 3, wherein the stabilizer is 5-10 parts by weight of asbestos ash. [7] A process for producing modified asphalt according to any one of claims 1-6, comprising: Heating and grinding components other than base asphalt to obtain a mixture; and Slowly adding the mixture to the base asphalt, which is heated to melt and stir evenly, and then naturally cooling after shearing by the emulsifier. [8] A process for producing modified asphalt according to claim 7, wherein the shearing speed is 17000 rpm - 20000 rpm and the shearing time is 20 min - 40 min.