Modified bitumen for durable thin surfacing and method of making, use, wearing course

Abstract

The application belongs to the technical field of polymer materials, and discloses a modified asphalt for durable thin-layer pavement, a preparation method, application and wearing layer thereof; the modified asphalt comprises the following components in mass fraction: 100 parts of asphalt, 10-20 parts of thermoplastic elastomer, 2-5 parts of tackifier and an additive; the tackifier is phthalonitrile resin; the thermoplastic elastomer contains not less than 90 wt% of SBS; the modified asphalt is synergistically modified by the tackifier and the thermoplastic elastomer, so that the obtained modified asphalt has excellent high-temperature performance, low-temperature performance and aging resistance, and is particularly suitable for durable thin-layer pavement; and the wearing layer prepared by the modified asphalt has excellent fatigue durability.

Description

Technical Field

[0001] This invention belongs to the field of asphalt material technology, specifically relating to a modified asphalt for durable thin-layer paving, its preparation method, uses, and wearing course. Background Technology

[0002] Ultra-thin overlays are currently one of the most commonly used techniques in highway maintenance, widely applied in preventative maintenance of asphalt and cement pavements on expressways, bridge decks, and tunnels, as well as in the upgrading and reconstruction of urban asphalt pavements. They significantly improve driving comfort and safety. However, the service life of ultra-thin overlays is typically no more than 5 years. Generally, reflective cracks begin to appear 3 years after application, and loosening and material loss begin to occur on the surface after 5 years, far below the 15-year design life of newly constructed asphalt pavements. Asphalt binder is the core component of ultra-thin overlays, and improving its durability is achieved by improving the performance of the asphalt binder. The standard JTG / T 5142-01—2021 specifies that the binder used in ultra-thin overlays is generally high-viscosity, high-elasticity asphalt, with core technical indicators including a softening point > 90℃, dynamic viscosity at 60℃ > 200,000 Pa·s, and ductility at 5℃ > 40 cm. The fatigue life of thin-layer overlay mixtures made with high-viscosity, high-elasticity asphalt is generally around 100,000 cycles. To further improve the durability of ultra-thin overlays, it is crucial to enhance the performance indicators of asphalt binders, including their high-temperature, low-temperature, aging resistance, and fatigue resistance.

[0003] In the field of asphalt modification technology, the improvement of high-temperature performance and low-temperature performance indicators are generally contradictory. Asphalt with excellent high-temperature performance indicators usually has average low-temperature performance indicators, and vice versa. Asphalt with excellent low-temperature performance indicators usually has unremarkable high-temperature performance indicators. Since ultra-thin overlays are located on the outermost layer of the road surface, they directly bear the combined effects of load and environment. Compared with other ordinary asphalt pavement layers, the working environment is more severe. Therefore, improving the high-temperature and low-temperature performance of high-viscosity and high-elasticity modified asphalt is of great significance for improving the service durability of ultra-thin overlays.

[0004] Therefore, the technical problem to be solved by the present invention is: how to develop a modified asphalt suitable for durable thin-layer paving that can significantly increase the service durability of the wearing course. Summary of the Invention

[0005] The purpose of this invention is to provide a modified asphalt for durable thin-layer paving, which contains a thermoplastic elastomer and a tackifier, wherein the tackifier is phthalonitrile resin. By using the tackifier and thermoplastic elastomer to synergistically modify the asphalt, the resulting modified asphalt simultaneously possesses excellent high-temperature performance, low-temperature performance, and fatigue durability, making it particularly suitable for durable thin-layer paving.

[0006] In addition, the present invention also provides a method for preparing the super-modified asphalt, its uses, and a wear layer made using the modified asphalt.

[0007] To achieve the above objectives, the present invention provides the following technical solution:

[0008] A modified asphalt for durable thin-layer paving comprises, by mass fraction, the following components: 100 parts asphalt, 10-20 parts thermoplastic elastomer, 2-5 parts tackifier, and additives;

[0009] The tackifier is phthalonitrile resin;

[0010] The plastic elastomer contains not less than 90 wt% SBS.

[0011] Preferably, the plastic elastomer further contains one or more combinations of SIS and SEBS.

[0012] Preferably, the asphalt is petroleum asphalt with a penetration of 30-500.

[0013] More preferably, the asphalt is Grade A petroleum asphalt for Road No. 70.

[0014] Preferably, by mass fraction, the additive contains 6-10 parts plasticizer, 2-6 parts dispersant, 1-2 parts antioxidant and 1-2 parts vulcanizing agent.

[0015] More preferably, the plasticizer is one or more combinations of di-n-butyl phthalate, trioctyl trimellitate, and pentaerythritol tetraoleate; the dispersant is N-methyl-2-pyrrolidone; the antioxidant is 2,6-di-tert-butyl-p-cresol; and the vulcanizing agent is VA-7.

[0016] Furthermore, this invention discloses a method for preparing the modified asphalt as described above. The specific method is as follows: heating the asphalt to 200°C, adding thermoplastic elastomer and tackifier and stirring, stirring for 30 minutes and then lowering the temperature to 180°C, adding plasticizer, dispersant and antioxidant in sequence, stirring for 4 hours, and finally adding vulcanizing agent and stirring for 2 hours to obtain the modified asphalt.

[0017] Furthermore, this invention discloses the use of the modified asphalt described above in the preparation of a wear layer for durable thin-layer pavement.

[0018] Finally, the present invention discloses a wear layer of a modified asphalt composition for durable thin-layer paving, the wear layer containing the modified asphalt as described above.

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

[0020] The modified asphalt prepared by this invention, through the synergistic effect of thermoplastic elastomer and tackifier, achieves a softening point >110℃ and a ductility >60cm at 5℃, simultaneously improving high-temperature and low-temperature performance indicators. Simultaneously, the aging resistance of the modified asphalt is significantly improved; after PAV aging, the ductility at 5℃ is >50cm, demonstrating resistance to long-term aging caused by sunlight and ultraviolet radiation. Secondly, the theoretical dynamic viscosity of the modified asphalt at 60℃ is >2 million Pa·s, more than 10 times the required dynamic viscosity index in existing standards, significantly enhancing the high-temperature deformation resistance of thin-layer overlay mixtures. Finally, the thin-layer asphalt mixture prepared using the modified asphalt of this invention exhibits a fatigue life exceeding 1 million cycles at 15℃ and 2000με, demonstrating significantly improved fatigue crack resistance and effectively enhancing the anti-reflective cracking performance of thin-layer overlays. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Reagents or instruments used that do not specify the manufacturer are all conventional products that can be purchased commercially.

[0022] Product Information:

[0023] Asphalt: Grade A petroleum asphalt for Road No. 70, purchased from Dongguan Taihe Asphalt Products Co., Ltd., Esso brand 70# base asphalt, with a penetration of 72 (0.1mm);

[0024] SBS: YH791-H produced by Sinopec Baling Petrochemical Plant has a styrene content of 30wt%.

[0025] SIS: JH-8153 produced by Ningbo Jinhaichenguang Chemical Co., Ltd., contains 15wt% styrene and 20wt% diblock.

[0026] SEBS: TAIPOL 6152P manufactured by TSRC Corporation Limited;

[0027] Phthalonil resin: Phthalonil resin produced by Wuhan Chengtian Fine Chemical Co., Ltd., CAS: 91-15-6; Part 1

[0028] The preparation methods for the following embodiments and comparative examples are shown below;

[0029] The modified asphalt is heated to 200°C, and thermoplastic elastomer and tackifier are added and stirred. After stirring for 30 minutes, the temperature is reduced to 180°C, and plasticizer, dispersant and antioxidant are added in sequence. Then, the mixture is stirred for 4 hours, and finally, vulcanizing agent is added and stirred for 2 hours to obtain the modified asphalt.

[0030] The formulations of each embodiment and comparative example are shown in Table 1.

[0031] Table 1. Modified Asphalt Formulation (parts by weight)

[0032]

[0033] The specific components of thermoplastic elastomers, tackifiers, and tackifiers can be found in Table 2.

[0034] Table 2 Detailed ingredient list

[0035]

[0036] Example 8

[0037] It is basically the same as Example 3, except that the plasticizer pentaerythritol tetraoleate is replaced by tributyl acetylacetonate.

[0038] Example 9

[0039] The example is essentially the same as Example 3, except that the antioxidant 2,6-di-tert-butyl-p-cresol is replaced by p-phenylenediamine.

[0040] Example 10

[0041] It is basically the same as Example 3, except that the vulcanizing agent VA-7 is replaced by sulfur powder.

[0042] Performance testing

[0043] The modified asphalts prepared in each embodiment and comparative example were subjected to the following tests;

[0044] Refer to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" JTG E20-2011;

[0045] Softening point: T 0606-2011;

[0046] Dynamic viscosity at 60℃: T 0620 -2000;

[0047] Ductility at 5℃: T 0605-2011;

[0048] PAV aging test method: T 0630-2011;

[0049] Fatigue testing method: T0739-2011;

[0050] The relevant test results are shown in Tables 3 and 4.

[0051] Table 3 Modified Asphalt Data Sheet

[0052]

[0053]

[0054] Table 4. Data on modified asphalt after one PAV long-term aging process

[0055]

[0056] Data Analysis

[0057] 1. As can be seen from the data of Examples 1 to 5, within the dosage range of the present invention, the modified asphalt obtained has good performance in terms of softening point, dynamic viscosity at 60°C, and ductility at 5°C, with Example 5 showing the best performance.

[0058] 2. As can be seen from the data in Examples 3 and 6-7, when the thermoplastic elastomer is used in combination with SBS and SIS or SEBS, the performance of the modified asphalt is further improved.

[0059] 3. As can be seen from the data of Examples 3 and 8-10, the preferred plasticizer of the present invention is pentaerythritol tetraoleate, the antioxidant is 2,6-di-tert-butyl-p-cresol, and the vulcanizing agent is VA-7.

[0060] 4. As can be seen from the data of Examples 3 and Comparative Examples 1-4, the phthalonitrile resin tackifier is a crucial and indispensable component of this invention, which can synergistically improve the performance of modified asphalt with thermoplastic elastomers; the effect of using other tackifiers such as PE, EVA, terpene resins and SBS in combination is far inferior to that of phthalonitrile resin.

[0061] 5. As can be seen from the data of Examples 3 and Comparative Examples 5-6, the type of thermoplastic elastomer selected in this invention is also crucial. SBS is the most preferred, while other thermoplastic elastomers such as SEPS and TPV are not effective.

[0062] Part Two

[0063] Wearing layers were prepared from the modified asphalts of Examples 3, 6-7, and Comparative Examples 1-6; the formulation ratios are as follows:

[0064] Modified asphalt: 2mm manufactured sand: 4mm basalt: 7mm basalt: mineral powder: polyester fiber = 8:15:40:40:5:0.3;

[0065] The specific preparation method is as follows:

[0066] The stone is heated to 190°C and the asphalt is heated to 185°C. The stone and fiber are mixed for 90 seconds, then high-viscosity asphalt is added and mixed for 90 seconds. Finally, mineral powder is added and mixed for 90 seconds to obtain an ultra-thin overlay mixture wear layer.

[0067] In this example, Example 3 corresponds to wear layer 1, Examples 6-7 correspond to wear layers 2-3, and Comparative Examples 1-6 correspond to wear layers 4-9.

[0068] The wear layer obtained above was tested using the following method:

[0069] The fatigue test was conducted according to the fatigue test method T0739-2011, under the following conditions: 15℃ and strain level 2000με.

[0070] The results are shown in Table 5.

[0071] Table 5. Test data for wear layer

[0072] Fatigue life / cycle Wear layer 1 1367480 Wear layer 2 1749670 Wear layer 3 1536920 Wear layer 4 123580 Wear layer 5 258490 Wear layer 6 324570 Wear layer 7 379630 Wear layer 8 248950 Wear layer 9 204830

[0073] As can be seen from the data in Table 6, the wearing course prepared using the modified asphalt of the present invention exhibits excellent fatigue life, especially wearing course 2. In contrast, the wearing course prepared using the modified asphalt in the comparative example has a fatigue life between 100,000 and 400,000 cycles, significantly shorter than that of the wearing course prepared using the modified asphalt in the examples. This demonstrates that the modified asphalt prepared by the present invention is particularly suitable for durable thin-layer paving.

[0074] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A modified asphalt for durable thin-layer pavement, characterized in that, By mass fraction, it includes the following components: 100 parts asphalt, 10-20 parts thermoplastic elastomer, 2-5 parts tackifier, and additives; The tackifier is phthalonitrile resin; The plastic elastomer contains not less than 90 wt% SBS; The plastic elastomer also contains one or more combinations of SIS and SEBS.

2. The modified asphalt according to claim 1, characterized in that, The asphalt is petroleum asphalt with a penetration of 30-500.

3. The modified asphalt according to claim 2, characterized in that, The asphalt mentioned is Grade A petroleum asphalt for Road No.

70.

4. The modified asphalt according to claim 1, characterized in that, The additives, by mass fraction, contain 6-10 parts plasticizer, 2-6 parts dispersant, 1-2 parts antioxidant and 1-2 parts vulcanizing agent.

5. The modified asphalt according to claim 4, characterized in that, The plasticizer is one or more combinations of di-n-butyl phthalate, trioctyl trimellitate, and pentaerythritol tetraoleate; the dispersant is N-methyl-2-pyrrolidone; the antioxidant is 2,6-di-tert-butyl-p-cresol; and the vulcanizing agent is VA-7.

6. The method for preparing modified asphalt according to any one of claims 1-5, characterized in that, The specific method is as follows: heat the asphalt to 200℃, add thermoplastic elastomer and tackifier and stir. After stirring for 30 minutes, lower the temperature to 180℃, add plasticizer, dispersant and antioxidant in sequence, stir for 4 hours, and finally add vulcanizing agent and stir for 2 hours to obtain the modified asphalt.

7. Use of the modified bitumen as described in any one of claims 1-5 in the preparation of a wearing course for durable thin-layer paving.

8. A wear layer for durable thin-layer paving, characterized in that, The wear layer contains the modified bitumen as described in any one of claims 1-5.

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