A high-performance asphalt concrete pavement material and its preparation method

Abstract

The present invention relates to the technical field of pavement materials, and particularly relates to a high-performance asphalt concrete pavement material and a preparation method thereof. The formula of the pavement material includes asphalt, high melt index SBS, fine aggregate, coarse aggregate, fly ash, water reducer, low-temperature anti-cracking agent and anti-freezing agent. Among them, the preparation method of the low-temperature anti-cracking agent includes stirring and melt spinning of homopolypropylene, nano-silicon carbide and low melt index SBS to obtain the low-temperature anti-cracking agent. By optimizing the ratio and adding specific components, the material has good low-temperature anti-cracking performance, anti-freezing performance and anti-stripping performance. The high-performance asphalt concrete pavement material provided by the present invention is expected to be applied to highway engineering and road construction fields in low-temperature regions.

Description

Technical Field

[0001] The present invention relates to the technical field of pavement materials, and particularly to a high-performance asphalt concrete pavement material and a preparation method thereof. Background Art

[0002] Asphalt concrete is a commonly used pavement material with good durability and load-bearing capacity. However, in low-temperature environments, asphalt concrete is prone to brittle cracks, reducing the service life and performance stability of the pavement. Traditional asphalt concrete is prone to cracks caused by freeze-thaw cycles at low temperatures, which brings problems to the use and maintenance of roads.

[0003] In order to overcome the brittle characteristics of asphalt concrete at low temperatures, many improvement measures have been proposed. These include adding modifiers, improving asphalt formulations, using better aggregates and fillers, etc. For example, the patent technical literature CN114477925B discloses a high and low temperature resistant asphalt concrete and a preparation method thereof, which is prepared from the following raw materials in parts by weight: 50-70 parts of water, 7-12 parts of modified SBS, 70-80 parts of asphalt base material, 3-5 parts of water reducing agent, 1-2 parts of stabilizer, 1-2 parts of cold-resistant modifier, 1-3 parts of high-temperature resistant modifier, 3-5 parts of sugar alcohol, 120-150 parts of cement, 10-15 parts of mineral powder, 17-25 parts of porous ceramics, and 5-12 parts of short-cut carbon fiber. The cold-resistant modifier is styrene-butadiene rubber and lignin. Although adding styrene-butadiene rubber and lignin to asphalt concrete helps to improve its low-temperature resistance, the improvement ability is limited. Especially in extremely low-temperature environments such as the north, the temperature is often below -10°C, and the lower temperature will make the brittle characteristics of the concrete more obvious, thereby reducing the service life of asphalt concrete. Summary of the Invention

[0004] In view of this, the purpose of the present invention is to provide a high-performance asphalt concrete pavement material and a preparation method thereof to solve the problem that asphalt concrete has obvious brittle characteristics at low temperatures.

[0005] Based on the above purpose, the present invention provides a high-performance asphalt concrete pavement material, including the following raw materials in parts by weight: 20-40 parts of asphalt, 0.2-0.4 parts of high melt index SBS, 80-150 parts of fine aggregate, 250-450 parts of coarse aggregate, 3-8 parts of fly ash, 2-5 parts of water reducing agent, 3-6 parts of low-temperature crack resistance agent, and 1-4 parts of antifreeze agent.

[0006] Among them, the preparation method of the low-temperature crack resistance agent is as follows:

[0007] S1: Add homopolypropylene, nano-silicon carbide, and low melt index SBS into a blender and stir for 3 - 5 min for premixing, then add them into a twin-screw extruder for melt extrusion. The extrusion temperature is 215 - 225 °C, and the screw speed is 350 - 450 r / min to obtain modified polypropylene masterbatch;

[0008] S2: Add the modified polypropylene masterbatch into a screw spinning machine for spinning. The diameter of the spinneret hole is 0.1 - 0.3 mm, and then stretch it at 100 - 105 °C with a draw ratio of 5 - 7 to obtain a low-temperature crack resistance agent.

[0009] Preferably, the high melt index SBS has a melt index of 10 - 20 g / 10 min at 200 °C and 5 kg.

[0010] Preferably, the low melt index SBS has a melt index of 0.5 - 1 g / 10 min at 200 °C and 5 kg.

[0011] Preferably, the particle size of the fine aggregate is 0.075 - 4.75 mm.

[0012] Preferably, the particle size of the coarse aggregate is 10 - 20 mm.

[0013] Preferably, the fly ash is Class I fly ash.

[0014] Preferably, the water reducing agent is one of polycarboxylate water reducing agent, sulfonate water reducing agent, and fatty acid salt water reducing agent.

[0015] Preferably, the antifreeze is a mixture of sodium acetate and ethylene glycol in a weight ratio of 1:1.

[0016] Preferably, the homopolypropylene in step S1 has a melt index of 3 - 8 g / 10 min at 230 °C and 2.16 kg.

[0017] Preferably, the particle size of the nano-silicon carbide in step S1 is 30 - 80 nm.

[0018] Preferably, the weight ratio of homopolypropylene, nano-silicon carbide, and low melt index SBS in step S1 is 3 - 6:0.1 - 0.5:0.3 - 1.5;

[0019] Preferably, the spinning temperature in step S2 is: Zone 1: 155 - 160 °C, Zone 2: 210 - 215 °C, Zone 3: 225 - 230 °C, Zone 4: 235 - 240 °C, Zone 5: 250 - 255 °C, and the melt box: 250 - 255 °C.

[0020] Preferably, the model of the high melt index SBS is Kraton-D0243; the model of the low melt index SBS is Kraton-D1101.

[0021] Furthermore, the present invention also provides a method for preparing the above-mentioned high-performance asphalt concrete pavement material, comprising the following steps:

[0022] (1) mixing and drying coarse aggregate, fine aggregate and fly ash at a drying temperature of 110-120° C. to obtain a mixture A;

[0023] (2) heating the asphalt to 165-180° C., then adding the mixture A and stirring, adding a water reducer, a low-temperature anti-cracking agent and an antifreeze agent during the stirring process, and mixing thoroughly to obtain a mixture B;

[0024] (3) Mixture B is placed into a mold and compacted to obtain a high-performance asphalt concrete pavement material.

[0025] Beneficial effects of the present invention:

[0026] Improve low-temperature crack resistance: By adding low-temperature anti-cracking agent, this material can significantly improve the brittle characteristics of asphalt concrete at low temperatures, improve its crack resistance, reduce the probability of pavement cracks, and further improve the low-temperature crack resistance by further limiting the melting index of the added SBS.

[0027] Improve durability: With high-performance raw material formula and optimized mix ratio, the material has high antifreeze performance, which can effectively reduce the damage of freeze-thaw cycles to pavement materials and increase the service life of asphalt concrete.

[0028] The preparation method is simple: the low-temperature anti-cracking agent is prepared by mixing, extruding, spinning and stretching different raw materials in a certain proportion. At the same time, the process for preparing the overall asphalt concrete pavement material is relatively simple and easy to operate and implement.

[0029] In summary, the high-performance asphalt concrete pavement material and its preparation method provided by the present invention can effectively improve the performance of asphalt concrete at low temperatures, enhance its crack resistance and frost resistance, thereby extending the service life of the pavement and reducing maintenance, and is expected to be applied to highway engineering and road construction in low-temperature areas. DETAILED DESCRIPTION

[0030] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with specific embodiments.

[0031] The sources or properties of the raw materials used in the present invention are as follows:

[0032] Homopolymer polypropylene was purchased from Dongguan Jinshixiang Plastic Raw Materials Co., Ltd., with a melt index of 4.5 g / 10 min (230 ° C, 2.16 kg); nano-silicon carbide was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd., with a product number of S104653 and a particle size of 40 nm; high melt index SBS was purchased from Dongguan Bailing New Materials Co., Ltd., with a model of Kraton-D0243 and a melt index of 18.5 g / 10 min (200 ° C, 5 kg) ; Low melt index SBS was purchased from Dongguan Bailing New Materials Co., Ltd., model Kraton-D1101, and the melt index was 0.8g / 10min (200℃, 5kg); the coarse aggregate was gravel with a particle size of 10-20mm; the fine aggregate was artificial sand with a particle size of 0.075-4.75mm, and the fly ash was Class I fly ash, all of which were purchased from a construction company; the water reducer was a polycarboxylic acid water reducer, model DonPCEHWR-502.

[0033] Embodiment 1: A high-performance asphalt concrete pavement material, the preparation method is as follows:

[0034] S1: 3g homopolymer polypropylene, 0.1g nano silicon carbide and 0.3g low melt index SBS were added into a mixer for stirring and premixing for 5min, and then added into a twin-screw extruder for melt extrusion at an extrusion temperature of 220°C and a screw speed of 400r / min to obtain a modified polypropylene masterbatch;

[0035] S2: Add the modified polypropylene masterbatch into a screw spinning machine for spinning, the spinneret diameter is 0.2 mm, the spinning temperature is 160°C in zone 1, 210°C in zone 2, 230°C in zone 3, 240°C in zone 4, 250°C in zone 5, the melt box is 250°C, and then stretched at 100°C with a stretch ratio of 6 to obtain a low-temperature anti-cracking agent;

[0036] S3: 250 g of coarse aggregate, 80 g of fine aggregate and 3 g of fly ash are stirred and dried at a drying temperature of 110° C. to obtain a mixture A;

[0037] S4: 20 g of asphalt was heated to 165° C., and then mixed material A was added and stirred. During the stirring process, 0.2 g of high melt index SBS, 2 g of polycarboxylate water reducer, 3 g of low temperature anti-cracking agent, 0.5 g of sodium acetate and 0.5 g of ethylene glycol were added, and the mixture was fully mixed to obtain a mixture B;

[0038] S5: The mixture B is loaded into a mold and compacted to obtain a high-performance asphalt concrete pavement material.

[0039] Embodiment 2: A high-performance asphalt concrete pavement material, the preparation method is as follows:

[0040] S1: 4.5 g homopolypropylene, 0.3 g nano silicon carbide and 1 g low melt index SBS were added into a mixer for stirring and premixing for 3-8 min, and then added into a twin-screw extruder for melt extrusion at an extrusion temperature of 215-225° C. and a screw speed of 400 r / min to obtain a modified polypropylene masterbatch;

[0041] S2: Add the modified polypropylene masterbatch into a screw spinning machine for spinning, the spinneret diameter is 0.2 mm, the spinning temperature is 160°C in zone 1, 210°C in zone 2, 230°C in zone 3, 240°C in zone 4, 250°C in zone 5, the melt box is 250°C, and then stretched at 100°C with a stretch ratio of 6 to obtain a low-temperature anti-cracking agent;

[0042] S3: 300 g of coarse aggregate, 110 g of fine aggregate and 5 g of fly ash are stirred and dried at a drying temperature of 110° C. to obtain a mixture A;

[0043] S4: 28 g of asphalt was heated to 170° C., and then mixed material A was added and stirred. During the stirring process, 0.28 g of high melt index SBS, 3.4 g of polycarboxylate water reducer, 4.2 g of low temperature anti-cracking agent, 1.2 g of sodium acetate and 1.2 g of ethylene glycol were added, and mixed thoroughly to obtain mixture B;

[0044] S5: The mixture B is loaded into a mold and compacted to obtain a high-performance asphalt concrete pavement material.

[0045] Embodiment 3: A high-performance asphalt concrete pavement material, the preparation method is as follows:

[0046] S1: 6 g homopolymer polypropylene, 0.5 g nano silicon carbide and 1.5 g low melt index SBS were added into a mixer for stirring and premixing for 5 min, and then added into a twin-screw extruder for melt extrusion at an extrusion temperature of 220° C. and a screw speed of 400 r / min to obtain a modified polypropylene masterbatch;

[0047] S2: Add the modified polypropylene masterbatch into a screw spinning machine for spinning, the spinneret diameter is 0.2 mm, the spinning temperature is 160°C in zone 1, 210°C in zone 2, 230°C in zone 3, 240°C in zone 4, 250°C in zone 5, the melt box is 250°C, and then stretched at 100°C with a stretch ratio of 6 to obtain a low-temperature anti-cracking agent;

[0048] S3: 450 g of coarse aggregate, 150 g of fine aggregate and 8 g of fly ash are stirred and dried at a drying temperature of 120° C. to obtain a mixture A;

[0049] S4: 40 g of asphalt was heated to 180° C., and then mixed material A was added and stirred. During the stirring process, 0.4 g of high melt index SBS, 5 g of polycarboxylate water reducer, 6 g of low temperature anti-cracking agent, 2 g of sodium acetate and 2 g of ethylene glycol were added, and mixed thoroughly to obtain mixture B;

[0050] S5: The mixture B is loaded into a mold and compacted to obtain a high-performance asphalt concrete pavement material.

[0051] Comparative Example 1: An asphalt concrete pavement material, the preparation method is as follows:

[0052] The difference between Comparative Example 1 and Example 2 is that no low-temperature anti-cracking agent is added in step S4.

[0053] Comparative Example 2: An asphalt concrete pavement material, the preparation method is as follows:

[0054] The difference between Comparative Example 2 and Example 2 is that nano-silicon carbide is not added in step S1.

[0055] Comparative Example 3: An asphalt concrete pavement material, the preparation method is as follows:

[0056] The difference between Comparative Example 3 and Example 2 is that low melt index SBS is not added in step S1.

[0057] Comparative Example 4: An asphalt concrete pavement material, the preparation method is as follows:

[0058] The difference between Comparative Example 4 and Example 2 is that nano-silicon carbide and low melt index SBS are not added in step S1.

[0059] Comparative Example 5: An asphalt concrete pavement material, the preparation method is as follows:

[0060] The difference between Comparative Example 5 and Example 2 is that the low melt index SBS in step S1 is replaced by a high melt index SBS.

[0061] Comparative Example 6: An asphalt concrete pavement material, the preparation method is as follows:

[0062] The difference between Comparative Example 6 and Example 2 is that the high melt index SBS in step S4 is replaced by a low melt index SBS.

[0063] Performance Test:

[0064] Low-temperature crack resistance: It is evaluated by the indirect tensile test at low temperature. According to the standard ASTM D6931-2012, the pavement materials prepared in Examples 1-3 and Comparative Examples 1-6 are made into standard non-permeable Marshall specimens, and then placed in an environmental chamber at -10°C, -20°C, and -30°C for 6 hours respectively. An indirect tensile test is carried out using a universal testing machine, and a splitting test fixture with a width of 12.7 mm is used as the loading strip to obtain the indirect tensile strength. The results are shown in Table 1.

[0065] Freeze-thaw splitting test: It is evaluated by the residual strength ratio. According to the standard JTG D50-2017, the pavement materials prepared in Examples 1-3 and Comparative Examples 1-6 are made into standard non-permeable Marshall specimens. The freeze-thaw temperature is -10°C, and the number of freeze-thaw cycles is 30 times. The strength of the freeze-thaw specimens and the strength of the non-freeze-thaw specimens are measured. The ratio of the strength of the freeze-thaw specimens to the strength of the non-freeze-thaw specimens is the residual strength ratio. The results are shown in Table 1.

[0066] Table 1 Performance test results

[0067]

[0068] Data analysis:

[0069] It can be seen from Examples 1-3 that the high-performance asphalt concrete pavement material prepared by the present invention has excellent low-temperature crack resistance, and after 30 freeze-thaw experiments, it still has a high residual strength ratio, indicating its excellent durability.

[0070] It can be seen from Example 2 and Comparative Example 1 that the low-temperature crack resistance agent prepared by the present invention has a crucial influence on the low-temperature crack resistance and water resistance of asphalt concrete pavement materials; it can be seen from the examples and Comparative Examples 2-4 that the improvement of the low-temperature crack resistance and water resistance of asphalt concrete pavement materials by the low-temperature crack resistance agent is mainly due to the introduction of nano-silicon carbide and SBS with a low melt index into the polypropylene fiber. This may be because nano-silicon carbide and SBS with a low melt index exist in the polypropylene fiber in the form of a uniform discrete phase, improving the brittle performance of the polypropylene fiber at low temperature, and then enhancing the low-temperature reinforcement effect of polypropylene in asphalt concrete.

[0071] It can be seen from Example 2 and Comparative Examples 5-6 that the selection of SBS in the asphalt concrete formulation and SBS in polypropylene is not arbitrary. Among them, SBS in the asphalt concrete formulation is more preferably low melt index SBS, which may be because low melt index SBS helps to promote the adhesion between asphalt and aggregate and polypropylene fiber. SBS in polypropylene is more suitable for high melt index SBS, mainly because high melt index SBS will not exhibit excessive fluidity during the preparation of asphalt concrete. Excessive fluidity will cause damage to polypropylene fibers, and high melt index SBS may be helpful for improving the brittle properties of polypropylene fibers at low temperatures.

[0072] Those of ordinary skill in the art should understand that the discussion of any of the above embodiments is only exemplary and is not intended to imply that the scope of the present invention (including the claims) is limited to these examples; under the concept of the present invention, the technical features in the above embodiments or different embodiments can also be combined, and the steps can be implemented in any order, and there are many other variations in different aspects of the present invention as described above, which are not provided in detail for the sake of brevity.

[0073] The present invention is intended to cover all such substitutions, modifications, and variations that fall within the broad scope of the appended claims. Therefore, any omission, modification, equivalent substitution, improvement, etc., made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A high-performance asphalt concrete pavement material, characterized in that The raw materials include the following parts by weight: 20-40 parts of asphalt, 0.2-0.4 parts of high melt index SBS, 80-150 parts of fine aggregate, 250-450 parts of coarse aggregate, 3-8 parts of fly ash, 2-5 parts of water reducing agent, 3-6 parts of low temperature anti-cracking agent, and 1-4 parts of antifreeze agent; The preparation method of the low temperature anti-cracking agent is as follows: S1: homopolymer polypropylene, nano silicon carbide and low melt index SBS are added into a mixer for stirring and premixing for 3-5 minutes, and then added into a twin-screw extruder for melt extrusion at an extrusion temperature of 215-225°C and a screw speed of 350-450r / min to obtain modified polypropylene masterbatch; S2: adding the modified polypropylene masterbatch into a screw spinning machine for spinning, the spinneret hole diameter is 0.1-0.3 mm, and then stretching at 100-105°C with a stretch ratio of 5-7 to obtain a low-temperature anti-cracking agent; The high melt index SBS has a melt index of 10-20 g / 10 min at 200° C. and 5 kg; the low melt index SBS has a melt index of 0.5-1 g / 10 min at 200° C. and 5 kg.

2. The high-performance asphalt concrete pavement material according to claim 1, characterized in that The particle size of the fine aggregate is 0.075-4.75 mm; the particle size of the coarse aggregate is 10-20 mm; and the fly ash is Class I fly ash.

3. The high-performance asphalt concrete pavement material according to claim 1, characterized in that, The water reducer is one of a polycarboxylate water reducer, a sulfonate water reducer and a fatty acid salt water reducer.

4. The high-performance asphalt concrete pavement material according to claim 1, characterized in that, The antifreeze agent is a mixture of sodium acetate and ethylene glycol in a weight ratio of 1:

1.

5. The high-performance asphalt concrete pavement material according to claim 1, characterized in that, In the step S1, the melt index of the homopolymerized polypropylene at 230° C. and 2.16 kg is 3-8 g / 10 min.

6. The high-performance asphalt concrete pavement material according to claim 1, wherein The particle size of the nano-silicon carbide in step S1 is 30-80 nm.

7. The high-performance asphalt concrete pavement material according to claim 1, wherein In the step S1, the weight ratio of homopolymer polypropylene, nano silicon carbide and low melt index SBS is 3-6:0.1-0.5:0.3-1.

5.

8. The high-performance asphalt concrete pavement material according to claim 1, wherein The spinning temperatures in step S2 are: 155-160°C in zone 1, 210-215°C in zone 2, 225-230°C in zone 3, 235-240°C in zone 4, 250-255°C in zone 5, and 250-255°C in the melt box.

9. The high-performance asphalt concrete pavement material according to claim 1, characterized in that, The model of the high melt index SBS is Kraton-D0243; the model of the low melt index SBS is Kraton-D1101.

10. A method for preparing a high-performance asphalt concrete pavement material according to any one of claims 1-9, characterized in that, The steps include: (1) Mixing and drying the coarse aggregate, fine aggregate and fly ash at a drying temperature of 110-120° C. to obtain a mixture A; (2) The asphalt is heated to 165-180°C, and then the mixture A is added and stirred. During the stirring process, high melt index SBS, water reducer, low temperature anti-cracking agent and antifreeze agent are added. After fully mixing, mixture B is obtained; (3) Mixture B is placed into a mold and compacted to obtain a high-performance asphalt concrete pavement material.

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