Asphalt concrete suitable for large temperature difference environment and preparation method thereof

Abstract

The invention provides asphalt concrete suitable for a large-temperature-difference environment and a preparation method of the asphalt concrete, and relates to the technical field of pavement concrete. The preparation method comprises the following steps: firstly, heating the aggregate, and then adding a part of the aggregate into a stirring device; adding the basalt fiber into the stirring device, then adding the remaining aggregate, and uniformly stirring; heating the asphalt, adding the asphalt into the stirring device, and continuously stirring; and finally, adding mineral powder into the stirring device, and uniformly stirring and mixing to obtain the asphalt concrete. The asphalt concrete prepared by adopting basalt fibers with different specifications and mixing amounts and setting different gradation is greatly improved in high and low temperature performance. The fiber distribution uniformity can be effectively improved through the addition mode of aggregate + fiber + aggregate, so that the prepared asphalt concrete has excellent high and low temperature performance, can adapt to weather conditions of the highest temperature of 70 DEG C and the lowest temperature of-25 DEG C on the surface of an asphalt pavement, and is suitable for a large temperature difference environment in Xinjiang.

Description

Technical Field

[0001] The present application relates to the technical field of pavement concrete, and in particular to an asphalt concrete suitable for use in environments with large temperature differences and a preparation method thereof. Background Art

[0002] Asphalt concrete is commonly known as asphalt concrete. Asphalt concrete is a mixture of asphalt, fine aggregate and filler prepared at high temperature in a certain proportion. It is often used to build road pavements. Its main components include mineral materials and asphalt, which are mixed under strictly controlled conditions. This material has the following significant characteristics: 1. Smooth surface and no joints: The surface of asphalt concrete pavement is smooth and has no joints, providing a smoother driving experience. 2. Driving comfort: Due to its flexible structure and low vibration, it has good stability during driving and provides good driving comfort. 3. Good visual effect: The visual effect of the vehicle and the road surface is good, which improves the overall beauty of the road. 4. Short construction period: The construction is fast and can be delivered quickly. It is particularly suitable for projects that require rapid construction, such as airport runways and highways. 5. Easy to maintain: Asphalt concrete pavement is easy to maintain, and damaged parts can be easily repaired or replaced. 6. Recyclable: Asphalt concrete can be recycled and reused, reducing the impact on the environment and saving resources. In addition, asphalt concrete also has the characteristics of high durability, good water resistance, strong wear resistance, etc., which enables it to maintain good performance in various climatic conditions. However, it also has some disadvantages, such as being greatly affected by temperature and aging of asphalt.

[0003] Xinjiang is located deep in the Eurasian continent, far from the ocean. Due to its geological structure of "three mountains and two basins" and unique landforms, coupled with strong solar radiation, Xinjiang is hot in summer and cold in winter, with a large disparity between hot and cold, and a large annual and daily temperature difference, forming a large temperature difference area. Under the influence of high and low temperature extreme climate, road rutting, low temperature cracking, fatigue damage and other diseases are very likely to occur. Fiber, as an external admixture, can improve road performance and has the advantages of high strength, wear resistance, durability and light weight. However, in areas with large temperature differences in Xinjiang, there is little research on the application of fiber in road paving, especially in some areas of Xinjiang with extreme road problems, such as Turpan and Altay, which puts higher performance requirements on asphalt concrete. Summary of the invention

[0004] The purpose of this application is to provide asphalt concrete suitable for large temperature difference environment and its preparation method, this process can improve the uniform dispersion of raw materials, and the obtained asphalt concrete has excellent high and low temperature performance. It can adapt to the climatic conditions of the highest temperature of asphalt pavement surface 70℃ and the lowest temperature -25℃.

[0005] In order to solve the above technical problems, the technical solution adopted in this application is:

[0006] On the one hand, the present application provides an asphalt concrete suitable for use in a large temperature difference environment, wherein the asphalt concrete comprises the following raw materials: aggregate, basalt fiber, asphalt and mineral powder, wherein the added mass of basalt fiber is 0.15-0.45%, and the added mass of asphalt is 3.5-5%.

[0007] On the other hand, the present application provides a method for preparing asphalt concrete suitable for use in a large temperature difference environment, comprising the following steps:

[0008] S1. First, heat the aggregate, and then add a portion of it into a stirring device;

[0009] S2. Add basalt fiber to the mixing device, and then add the remaining aggregate and mix well;

[0010] S3, heating the asphalt, then adding it into the stirring device and continuously stirring;

[0011] S4. Finally, add the mineral powder into the stirring device, stir and mix evenly to obtain the asphalt concrete.

[0012] Compared with the prior art, the embodiments of the present application have at least the following advantages or beneficial effects:

[0013] This application uses basalt fibers of different specifications and dosages of 12mm and 6mm, and sets different gradations to prepare asphalt concrete, which has greatly improved high and low temperature performance. The addition of aggregate + fiber + aggregate can effectively improve the uniformity of fiber distribution, so that the prepared asphalt concrete has excellent high and low temperature performance, which can adapt to the climatic conditions of the highest temperature of 70℃ and the lowest temperature of -25℃ on the asphalt pavement surface, and is suitable for the large temperature difference environment in Xinjiang. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the embodiments will be briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present application and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without paying creative work.

[0015] Figure 1 This is a schematic diagram of the mixing principle of aggregate and fiber in Example 1 of the present application;

[0016] Figure 2 This is the process and product morphology diagram of the comparison group in Experimental Example 2 of this application;

[0017] Figure 3 This is a diagram of the process and product morphology of the experimental group in Experimental Example 2 of this application. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical scheme and advantages of the embodiments of the present application clearer, the technical scheme in the embodiments of the present application will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to the conventional conditions or the conditions recommended by the manufacturer. If the manufacturer is not specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. The present application will be described in detail below with reference to specific embodiments.

[0020] An asphalt concrete suitable for use in a large temperature difference environment comprises the following raw materials: aggregate, basalt fiber, asphalt and mineral powder, wherein the added mass of basalt fiber is 0.15-0.45%, and the added mass of asphalt is 3.5-5%.

[0021] In some embodiments of the present application, the raw material gradation of the asphalt concrete is AC-13, AC-16 or AC-25, and the asphalt is 90# asphalt.

[0022] In some embodiments of the present application, the basalt fibers include short-cut basalt fibers and long-cut basalt fibers. The length of the short-cut basalt fibers is 3 mm, and the length of the long-cut basalt fibers is 12 mm.

[0023] In some embodiments of the present application, the mineral powders described above have a particle size of less than 0.075 mm accounting for 75-85%, a particle size of less than 0.3 mm accounting for 90-95%, and a particle size of less than 0.6 mm accounting for 100%.

[0024] The performance indicators of the raw materials used in the examples of the present application are shown in Tables 1 to 4.

[0025] Table 1 90# asphalt performance indicators:

[0026] Test items unit Specification requirements Test results Test methods Needle penetration (25℃, 5s, 100g) 0.1mm 80～100 88.9 T0604 Softening point (R&B) ℃ ≥45 47.6 T0606 Dynamic viscosity at 60℃ Pa·s ≥160 172.4 T0620 10℃ Elongation cm ≥45 52 T0605 15℃ Elongation cm ≥100 >150 T0605

[0027] Table 2 Aggregate (limestone) technical indicators:

[0028]

[0029]

[0030] Table 3 Mineral powder technical indicators:

[0031]

[0032] Table 4 Fiber technical indicators:

[0033] Technical indicators unit Chopped Basalt Fiber Long cut basalt fiber Fiber diameter μm 17 17 Cutting length mm 6 12 proportion <![CDATA[g / cm 3 ]]> 2.65 2.65 Melting point ℃ 1450～1500 1450～1500 tensile strength MPa 2000 1800 Elastic modulus GPa 85 85 Elongation at break ％ 3.2 2.9

[0034] A method for preparing asphalt concrete suitable for use in a large temperature difference environment comprises the following steps:

[0035] S1. First, heat the aggregate, and then add a portion of it into a stirring device;

[0036] S2. Add basalt fiber to the mixing device, and then add the remaining aggregate and mix well;

[0037] S3, heating the asphalt, then adding it into the stirring device and continuously stirring;

[0038] S4. Finally, add the mineral powder into the stirring device, stir and mix evenly to obtain the asphalt concrete.

[0039] In some embodiments of the present application, the aggregate in the above step S1 is heated to 170-190° C. and maintained at a constant temperature for 4-8 hours.

[0040] In some embodiments of the present application, the portion of aggregate in the above step S1 is 40-60% of the total amount of aggregate.

[0041] In some embodiments of the present application, the stirring time in the above step S2 is 20-40s; the continuous stirring time in the step S3 is 80-120s; and the stirring and mixing time in the step S4 is 80-150s.

[0042] In some embodiments of the present application, the heating temperature of the asphalt in the above step S3 is 130-150°C, and the constant temperature is maintained for 2-3 hours after heating.

[0043] The features and performance of the present application are further described in detail below in conjunction with the embodiments.

[0044] Example 1

[0045] An asphalt concrete suitable for use in a large temperature difference environment is prepared by the following method:

[0046] Weigh the raw materials: aggregate, basalt fiber, asphalt and mineral powder. The basalt fiber is 6mm short chopped basalt fiber, and the added mass is 0.15%; the added mass of asphalt is 4.5%, and the grading type used is AC-16.

[0047] First, heat the limestone aggregate to 180°C and keep it at a constant temperature for 4 hours, then take 45% of it and add it to the asphalt mixing pot; add basalt fiber to the asphalt mixing pot, and then add the remaining 55% of the aggregate, stir for 20 seconds to make it fully mixed; take 90# base asphalt and heat it to 135°C, keep it for 2 hours, then add it to the stirring device, and continue stirring for 90 seconds; finally, add mineral powder to the stirring device, stir and mix for 90 seconds to obtain the asphalt concrete of this embodiment, and the mixing temperature in the stirring pot of this embodiment is 160°C.

[0048] The preparation process principle of aggregate + fiber + aggregate in this embodiment is as follows Figure 1 As shown, during the mixing process of the stacked structure, the friction movement between the aggregates can effectively disperse the basalt fibers in a compacted state, thereby reducing the problem of fibers and asphalt sticking together.

[0049] Example 2

[0050] An asphalt concrete suitable for use in a large temperature difference environment is prepared by the following method:

[0051] Weigh the raw materials: aggregate, basalt fiber, asphalt and mineral powder. The basalt fiber is 6mm short chopped basalt fiber, and the added mass is 0.3%; the added mass of asphalt is 4.2%, and the grading type used is AC-25.

[0052] First, heat the limestone aggregate to 185°C and keep it at a constant temperature for 6 hours, then take 50% of it and add it to the asphalt mixing pot; add basalt fiber to the asphalt mixing pot, and then add the remaining 50% of the aggregate, and stir for 30 seconds to make it fully mixed; take 90# base asphalt and heat it to 135°C, keep it for 3 hours, then add it to the stirring device, and continue stirring for 90 seconds; finally, add mineral powder to the stirring device, stir and mix for 100 seconds to obtain the asphalt concrete of this embodiment. The mixing temperature in the stirring pot of this embodiment is 160°C.

[0053] Example 3

[0054] An asphalt concrete suitable for use in a large temperature difference environment is prepared by the following method:

[0055] Weigh the raw materials: aggregate, basalt fiber, asphalt and mineral powder. The basalt fiber is 12mm long cut basalt fiber, and the added mass is 0.3%; the added mass of asphalt is 4.0%, and the grading type used is AC-16.

[0056] First, heat the limestone aggregate to 190°C and keep it at a constant temperature for 4 hours, then take 60% of it and add it to the asphalt mixing pot; add basalt fiber to the asphalt mixing pot, and then add the remaining 40% of the aggregate, and stir for 40 seconds to make it fully mixed; take 90# base asphalt and heat it to 130°C, keep it for 2.5 hours, then add it to the stirring device, and continue stirring for 120 seconds; finally, add mineral powder to the stirring device, stir and mix for 90 seconds to obtain the asphalt concrete of this embodiment, and the mixing temperature in the stirring pot of this embodiment is 160°C.

[0057] Experimental Example 1

[0058] 1. This experimental example sets up 9 test groups, and the optimal asphalt dosage is calculated by making Marshall specimens and testing, as shown in Tables 4 and 5.

[0059] Table 4 Experimental plan

[0060]

[0061] Table 5 Marshall test results

[0062]

[0063]

[0064] It can be seen from the table that when the fiber content is 0.15%, the optimal asphalt dosage of short-cut basalt fiber and long-cut basalt fiber both increase by 0.1%; when the fiber content is 0.3%, the two types of fibers increase by 0.2% and 0.1% respectively; when the fiber content is 0.45%, the optimal asphalt dosage of the two types of fibers increase by 0.2% and 0.2% respectively. Comprehensive analysis shows that under different gradations, the optimal asphalt dosage increases by 0.1% for every 0.2% increase in the content of short-cut basalt fiber and long-cut basalt fiber. This is because the different physical properties of the fibers lead to different asphalt adsorption contents in the fibers, which leads to different optimal asphalt dosages for fiber asphalt concrete.

[0065] 2. This experimental example explores the high-temperature stability of asphalt concrete. The rutting test was carried out in the indoor laboratory. The wheel rolling method was to first fix 4 driving times, then turn 180° and roll 8 driving times, and finally let it stand indoors for 12 hours for the rutting test. The test temperature was selected as the conventional 60°C. Considering the large temperature difference in Xinjiang, the difference between high and low temperatures is huge. The conventional rutting temperature cannot fully simulate the high-temperature areas in Xinjiang, such as Turpan. At the same time, the specification also has needs for high-temperature areas, and the test temperature can be increased to 70°C. Therefore, based on the large temperature difference environment conditions, this article adds a rutting test at 70°C. The rutting plate specimens are kept warm at the specified temperature for 6 hours before the rutting test. The rutting test of the two is used to analyze the influence of various factors on the performance of asphalt concrete. The dynamic stability calculation method adopts formula 1:

[0066]

[0067] Where:

[0068] DS——dynamic stability, times / mm;

[0069] N——Rubber wheel travel speed, take 42 times / min;

[0070] d60——rutting depth corresponding to 60min(t2);

[0071] d45——rutting depth corresponding to 45min(t1);

[0072] C1——Testing machine type coefficient, which is taken as 1.0 in this test;

[0073] C2——specimen coefficient, which is taken as 1.0 in this test.

[0074] The results are shown in Tables 6 and 7.

[0075] Table 6 60℃ high temperature rutting test results:

[0076]

[0077] Table 7 70℃ high temperature rutting test results:

[0078]

[0079]

[0080] As can be seen from Table 6, under the test conditions of 60°C, it can be seen that the order of improving the rutting performance of asphalt concrete at different gradations and different fiber contents is short-cut basalt and long-cut basalt fibers, and the improvement of rutting performance by long-cut basalt fibers is not obvious enough;

[0081] It can be seen from Table 7 that under the 70°C test condition, the dynamic stability of the rutting test is significantly reduced compared with the 60°C test condition. Test groups 8 and 9 do not even meet the 800 times / mm performance index required by the specification

[72] .

[0082] In summary, after the test environment was changed from 60℃ to 70℃, the various rutting properties were significantly reduced, which further demonstrated that asphalt concrete has extremely strong temperature sensitivity. At the same time, basalt fiber can reduce the temperature sensitivity of asphalt concrete, thereby improving its high-temperature stability at different temperatures and different gradations. In the two test environments, the primary and secondary relationships of the influence on the high-temperature stability and deformation resistance of rutting are short-cut basalt fiber and long-cut basalt fiber. The dynamic stability of rutting is negatively correlated with the rutting depth, that is, the greater the dynamic stability, the smaller the deformation of the rutting specimen.

[0083] 3. This experimental example explores the low-temperature crack resistance of asphalt concrete. According to the completed mineral mix design and the optimal asphalt dosage, 9 groups of tests were carried out with reference to the design parameters given in the specification, and two parallel specimens were made for each group of tests. First, the rutting board was made in the indoor laboratory. The wheel rolling method was fixed for 4 driving times, and then the wheel rolling was turned 180° for 8 driving times. Finally, it was demoulded after standing indoors for 12 hours, and then cut into prismatic beam specimens with a length of 250mm±2mm, a width of 30mm±2mm, and a height of 35mm±2mm. The size of the cut beam specimens was measured, and the specimens with unqualified sizes were discarded. Then the specimens were placed in an environmental box at -10℃ for curing for no less than 6h. The test was placed on a support with a span of 200mm. The test temperature was selected to be carried out in an environment of -10℃, and the loading rate was fixed at 50mm / min. The maximum load at the time of test failure and the mid-span deflection at the time of specimen failure were measured by the test equipment. The various performance indicators of the specimens were calculated according to formula 2-4. The specific calculation formula is as follows.

[0084]

[0085] Where:

[0086] RB——flexural tensile strength of the specimen at failure (MPa);

[0087] εB——maximum bending strain of the specimen at failure (με);

[0088] SB——Bending stiffness modulus of the specimen at failure (MPa);

[0089] PB - maximum load when the specimen is damaged (N);

[0090] d——mid-span deflection of the specimen when it fails (mm);

[0091] L——specimen length (mm);

[0092] b——test piece width (mm);

[0093] h——test piece height (mm).

[0094] The results are shown in Table 8.

[0095] Table 8 Low temperature bending beam test results:

[0096]

[0097]

[0098] It can be seen from Table 8 that the low-temperature performance of asphalt concrete with fiber addition is generally improved; the maximum flexural strains of test groups 1, 3, and 5 all reach the highest values ​​under this gradation, which are 32.4%, 22.2%, and 67.7% higher than those of ordinary asphalt concrete, respectively. At the same time, it is found that the fiber types of these three test groups are all short-cut basalt fibers, which indicates that compared with long-cut basalt fibers, it has the best effect on improving the low-temperature performance of asphalt concrete; other low-temperature performance indicators of test groups 1, 4, and 7 are also ahead of other test groups under the same gradation.

[0099] 4. This experimental example explores the water temperature performance of asphalt concrete: water-immersion Marshall test and freeze-thaw splitting test. The water-immersion Marshall test and freeze-thaw splitting test use double-sided compaction 75 times and 50 times to form cylindrical specimens with a height of 63.5mm±1.3mm and a diameter of 101.6mm±0.25mm, respectively. The specimens are demoulded after cooling to room temperature for no less than 12 hours. In the water-immersion Marshall test, 4 specimens are placed in a 60℃ water bath for 30 minutes to test their stability MS1 and flow value, and the other 4 specimens are placed in a 60℃ water bath for 48 hours to test their stability MS2 and flow value. The freeze-thaw splitting test divided the eight specimens into two groups for environmental maintenance. Four of the specimens were directly stored indoors for standby after demolding, and the other four were vacuumed for 15 minutes using the saturated water method. After the pressure was released, they were placed in water for 0.5 hours, then taken out and put into a plastic bag and placed in a -18℃ refrigerator for 16 hours. After the refrigeration, the plastic bag was immediately removed and placed in a 60℃ water bath for 24 hours. Then the eight specimens were uniformly placed in a 25℃ constant temperature water tank for 2 hours, and finally the freeze-thaw splitting test was carried out. The test temperature was 25℃, the loading rate was 50mm / min, and the splitting tensile strength RT1 and RT2 of the two groups of specimens were directly measured by the test equipment. The residual stability MS0 and the freeze-thaw splitting test strength ratio TSR were calculated by formula 5-6. The specific calculation formulas are shown below.

[0100]

[0101] Where:

[0102] MS0——Residual stability of specimen (%);

[0103] MS2——Stability of the specimen after 48h of curing (KN);

[0104] MS1——Stability of the specimen after 30 minutes of curing (KN).

[0105] TSR——freeze-thaw splitting test strength ratio (%);

[0106] ——The average value of splitting tensile strength of effective specimens after freeze-thaw cycles (MPa);

[0107] ——The average value of splitting tensile strength of effective specimens without freeze-thaw cycles (MPa).

[0108] The results are shown in Tables 9 and 10.

[0109] Table 9 Immersion Marshall test results

[0110]

[0111]

[0112] Table 10 Freeze-thaw splitting test results

[0113]

[0114] It can be seen from Table 9 that the residual stability results of the submerged Marshall test under the test meet the requirements of the specification. The residual stability of the six groups of tests with fiber addition is higher than that without fiber addition, which shows that fiber can improve the residual stability of asphalt concrete and improve its water stability.

[0115] It can be seen from Table 10 that the performance of the 12 groups of freeze-thaw splitting tests under the test all meet the requirements of the specification, and the freeze-thaw splitting strength ratio of the fiber-added ones is higher than that of the fiber-free ones, which indicates that the fiber can enhance the water stability of asphalt concrete to a certain extent;

[0116] In summary, under the same gradation, the addition of fiber increases the residual stability of asphalt concrete by 4.1% to 12.8%, and the freeze-thaw splitting strength ratio by 2.5% to 11.3%;

[0117] 5. This experimental example explores the viscoelastic properties of asphalt concrete. First, a cylindrical specimen with a diameter of 150 mm and a height of 170 mm was formed by the rotary compaction method. After demolding, it was naturally cooled for 12 hours, cored and drilled, and cut into standard specimens with a diameter of 100 mm and a height of 150 mm for the determination of the dynamic modulus. Finally, an asphalt concrete multifunctional testing machine (UTM-130) was used to conduct a dynamic modulus test of asphalt concrete. During the test, an offset sinusoidal wave load was applied to the specimen. The test temperatures were selected from -10°C and 21.1°C from low to high, and the loading frequencies were 0.1, 0.5, 1.0, 5.0, 10, and 25 Hz, and the dynamic modulus |E*| and phase angle were obtained. The results are shown in Tables 11 and 12.

[0118] Table 11 Asphalt concrete dynamic modulus test results:

[0119]

[0120] It can be seen from Table 11 that the dynamic modulus of asphalt concrete increases with the increase of frequency, and the dynamic modulus curve of asphalt concrete mixed with fibers is always higher than that of ordinary asphalt concrete, indicating that at the same temperature and load frequency, the fiber has a better stabilizing effect on the adsorption of more asphalt, making the asphalt concrete more integrated, with a higher dynamic modulus value, and better high temperature stability and low temperature stability.

[0121] Table 12 Asphalt concrete dynamic modulus test results:

[0122]

[0123]

[0124] It can be seen from Table 12 that the dynamic modulus of asphalt concrete increases with the increase of frequency, and the dynamic modulus curve of asphalt concrete mixed with fibers is always higher than that of ordinary asphalt concrete, indicating that at the same temperature and load frequency, the fiber has a better stabilizing effect on the adsorption of more asphalt, making the asphalt concrete more integrated, with a higher dynamic modulus value, and better high temperature stability and low temperature stability.

[0125] When the test temperature is -10℃, the phase angle decreases rapidly with the increase of loading frequency; at 21.1℃, the phase angle increases steadily with the increase of loading frequency, and then decreases rapidly; in the process of transition from low temperature to normal temperature, the phase angle of fiber asphalt concrete decreases with the increase of loading frequency. This is because when the temperature is low, the adhesion between asphalt and mineral aggregate is strong, and the asphalt concrete in the viscoelastic state under load has small deformation and phase angle, which can maintain low-temperature crack resistance well; as the temperature rises, the phase angle changes slowly and eventually tends to be horizontal. This may be because the addition of fiber enhances the bonding between asphalt and aggregate, improves the overall resistance of the specimen to high-temperature deformation, and weakens the elastic trend. This further proves that fiber improves the high-temperature performance of asphalt concrete.

[0126] Experimental Example 2

[0127] This experimental example explores the effect of different raw material addition sequences on asphalt concrete.

[0128] The control group used the traditional asphalt concrete mixing steps: first, the basalt aggregate was heated and placed in a mixing pot, then the basalt fiber was added and mixed at 160°C for 20 seconds, and then the heated asphalt was added and mixed at 160°C for 90 seconds. Figure 2 shown.

[0129] The experimental group adopted the preparation process of Example 2, and the asphalt concrete after the process and mixing was as follows: Figure 3 shown.

[0130] from Figure 2 and Figure 3 It can be seen that the basalt fibers and aggregates in the control group are unevenly dispersed and agglomerated. After adding asphalt, the basalt fibers and asphalt are severely adhered and agglomerated, while there is no agglomeration between the basalt fibers and asphalt in the experimental group.

[0131] In summary, the asphalt concrete and its preparation method suitable for use in a large temperature difference environment according to the embodiment of the present application have the following advantages: the asphalt concrete prepared by using basalt fibers of different specifications and dosages of 12mm and 6mm and setting different gradations has greatly improved high and low temperature performance. The addition of aggregate + fiber + aggregate can effectively improve the uniformity of fiber distribution, so that the prepared asphalt concrete has excellent high and low temperature performance, can adapt to the climatic conditions of the highest temperature of 70°C and the lowest temperature of -25°C on the surface of the asphalt pavement, and is suitable for use in the large temperature difference environment in Xinjiang.

[0132] The embodiments described above are part of the embodiments of the present application, rather than all of the embodiments. The detailed description of the embodiments of the present application is not intended to limit the scope of the present application for protection, but merely represents the selected embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the present application.

Claims

1. An asphalt concrete suitable for use in environments with large temperature differences, characterized in that: The asphalt concrete comprises the following raw materials: Aggregate, basalt fiber, asphalt and mineral powder, wherein the added mass of basalt fiber is 0.15-0.45%, and the added mass of asphalt is 3.5-5%.

2. The asphalt concrete suitable for use in a large temperature difference environment according to claim 1, characterized in that: The raw material gradation of the asphalt concrete is AC-13, AC-16 or AC-25, and the asphalt is 90# asphalt.

3. The asphalt concrete suitable for use in a large temperature difference environment according to claim 1, characterized in that: The basalt fibers include short-cut basalt fibers and long-cut basalt fibers. The length of the short-cut basalt fibers is 3 mm, and the length of the long-cut basalt fibers is 12 mm.

4. The asphalt concrete suitable for use in a large temperature difference environment according to claim 1, characterized in that: Among the mineral powder, the particle size of less than 0.075 mm accounts for 75-85%, the particle size of less than 0.3 mm accounts for 90-95%, and the particle size of less than 0.6 mm accounts for 100%.

5. A method for preparing asphalt concrete suitable for use in a large temperature difference environment as claimed in any one of claims 1 to 4, characterized in that: The following steps are involved: S1. First, heat the aggregate, and then add a portion of it into a stirring device; S2. Add basalt fiber to the mixing device, and then add the remaining aggregate and mix well; S3, heating the asphalt, then adding it into the stirring device and continuously stirring; S4. Finally, add the mineral powder into the stirring device, stir and mix evenly to obtain the asphalt concrete.

6. The method for preparing asphalt concrete suitable for use in a large temperature difference environment according to claim 5, characterized in that: The aggregate in step S1 is heated to 170-190° C. and maintained at a constant temperature for 4-8 hours.

7. The method for preparing asphalt concrete suitable for use in a large temperature difference environment according to claim 5, characterized in that: The portion of aggregate in step S1 is 40-60% of the total amount of aggregate.

8. The method for preparing asphalt concrete suitable for use in a large temperature difference environment according to claim 8, characterized in that: The stirring time in step S2 is 20-40s; the continuous stirring time in step S3 is 80-120s; and the stirring and mixing time in step S4 is 80-150s.

9. The method for preparing asphalt concrete suitable for use in a large temperature difference environment according to claim 5, characterized in that: The heating temperature of the asphalt in the step S3 is 130-150° C., and the constant temperature is maintained for 2-3 hours after heating.

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