Study on Properties of Drainage SBS Modified Asphalt Mixture with Fiber

School of Civil Engineering and Communication, North China University of Water Resources and Electric Power, Zhengzhou 450045, Henan, China Henan Province Engineering Technology Research Center of Environment Friendly and High-Performance Pavement Materials, Zhengzhou 450045, Henan, China Zhengzhou City Key Laboratory of Environmentally Friendly High Performance Road and Bridge Materials, Zhengzhou 450045, Henan, China


Introduction
With the proposal of 'sponge city' construction in China, drainage asphalt pavement has attracted more and more attention [1][2][3]. e drainage asphalt pavement surface layer adopts large void open graded asphalt mixture, and the middle and lower layers adopt dense graded asphalt mixture. It has good noise reduction, drainage, and antiskid performance, which can effectively improve the safety of travel in rainy days and reduce noise pollution to a certain extent [4,5]. Due to the small content of fine aggregate and mineral powder in the drainage asphalt pavement mixture, there are a large number of communicating interstices, air and rainwater are easy to penetrate into the internal structure, and they are prone to aging and reduce the service life; drainage asphalt mixture is an open-graded skeleton void structure with more coarse aggregate and less adhesive force, so the asphalt binder used in drainage asphalt pavement should have strong adhesion, antistripping, and water resistance to aggregate [6][7][8][9][10][11][12][13].
In order to strengthen the high and low temperature performance, skid resistance, and water stability of drainage pavement, many related studies have been conducted in China and abroad. In the 1960s, Germany first proposed the "large void asphalt pavement," namely, petroleum asphalt (spraying anionic emulsified asphalt) pavement, which was developed and applied to airport runways. e purpose is to enhance the skid resistance of runways and reduce and avoid the water drift generated by aircraft during the taxiing in rainy days [14]. In the 1990s, the paving test of porous asphalt pavement was carried out in Britain. e asphalt mixture used in the test section is rubber asphalt or No. 100 matrix asphalt, and fiber and 2% lime are added. It is proved that the pavement has the effect of reducing noise and rainwater film [15]. In 1999, fiber was introduced into China for the first time, and some highway projects began to use fiber as additive to improve the road performance of asphalt mixture. rough exploring the mechanism of basalt fiber in asphalt mixture [16,17], it is found that basalt fiber has the best high temperature stability and shear strength among several fibers, which can significantly improve the rutting resistance factor and water stability of asphalt mortar [18][19][20][21][22]. Toughened polystyrene (TPS) is a high viscosity asphalt additive, which can significantly improve the high and low temperature performance of asphalt and improve the fatigue performance of asphalt pavement. However, due to the high price of TPS high viscosity asphalt modifier, it is difficult to promote it [23,24]. Later, SBS modifier was widely used in China. SBS is a kind of thermoplastic elastomer, which has the elasticity of rubber at room temperature and can melt and flow at high temperature. e incorporation of SBS modifier into asphalt mixture can greatly improve the rutting resistance, and the high temperature stability is also better, and the water stability of drainage asphalt mixture is effectively improved [25][26][27][28][29].
Basalt fiber can improve the dispersion of mineral powder, has toughening and reinforcing effect, and can improve pavement performance and prolong service life; SBS modifier has the advantages of high softening point, high viscosity, large elongation, and strong antistripping property. Adding SBS modifier into asphalt mixture can make it have good high temperature stability and durability. erefore, both of them are used for drainage asphalt mixture to further enhance the high and low temperature stability and water damage resistance of drainage asphalt pavement. To this end, this paper intends to prepare the drainage SBS modified asphalt mixture with basalt fiber and puts forward the preparation method of high-speed shear SBS modified asphalt. e rheological properties of modified asphalt are analyzed by DSR test and BBR test. e high temperature stability, low temperature crack resistance, water stability, and drainage performance are comprehensively studied through rutting test, immersion Marshall test, freeze-thaw splitting test, and low temperature bending test. e mechanism of basalt fiber reinforced asphalt mixture on road performance is further studied from the micro level by scanning electron microscopy, so as to promote the development of drainage asphalt pavement in China.  Table 3.

Mineral Fines.
e technical indicators of ore powder are shown in Table 4.

Fiber.
e drainage asphalt mixture has large void ratio and low aggregate specific surface area, which may lead to segregation of mixture during paving and rolling. erefore, the pavement performance of the mixture can be improved by adding fiber to increase the thickness of asphalt film and the grip strength between asphalt and mineral. e nominal length of basalt fiber and wood fiber is 6 mm, and the diameter of single fiber is 16 μm, and the technical indexes are shown in Table 5

Preparation Method of Modified
Asphalt. SBS modified asphalt with 7% SBS modifier and TPS modified asphalt with 12% TPS modifier were prepared by high-speed shearing method. e specific preparation process of modified asphalt is as follows: 3.1.1. Title of Raw Materials. According to the amount and blending ratio of modified asphalt required in the test, the amount of matrix asphalt and modifier was determined. e modifier is slowly and evenly added to the matrix asphalt heated to 160°C.

Preswelling.
e research shows that the polymer is uniformly distributed in the base asphalt, and the improvement effect of asphalt performance will be more significant when the volume is expanded to 10 times the original volume, and then the high-speed shear is carried out.
at is, after the modifier is added to asphalt, the polymer is preswelling, which makes it easier to shear and grind. erefore, this experiment first sheared at a low speed of 600 r/min for 15 min to ensure the full swelling of the modifier.

High-Speed Shearing.
After the modifier is fully swelling, the shear rate is increased to 4500 r/min under the condition of high-speed shear 40 min, so that the different components of asphalt are redistributed to prepare the required modified asphalt.    Advances in Civil Engineering 3 sieve hole is adjusted, and three initial grading schemes are selected based on the grading median, as shown in Table 6. e initial asphalt contents of the three groups of gradations are obtained by theoretical calculation, which are 4.9%, 4.7%, and 4.3%, respectively. en, the Marshall specimens of SBS drainage asphalt mixture and TPS drainage asphalt mixture are formed by the target gradation and the corresponding initial asphalt content, and the void ratio of the specimens is measured. Studies have shown that when the target porosity is about 20%, the drainage asphalt pavement can not only ensure excellent drainage performance, but also ensure good structural performance.

Determination
erefore, 20% was selected as the target porosity for this topic.
e test results are shown in Table 7.
e analysis in Table 7 shows that the void ratio of gradation 1 is small, and the void ratio of gradation 3 is large. e void ratio of SBS drainage asphalt mixture and TPS drainage asphalt mixture at gradation 2 is closer to the target void ratio of 20%. So, choose gradation 2 as target gradation.

Determination of Optimum Asphalt Content
(1) Drain-Down Test. Leakage test is using asphalt mixture test procedures T0732 beaker method for testing; the specific steps are as follows: 1 kg of asphalt mixture will be mixed into the mass of 800 ml dry clean beaker, called the total mass of m 1 . e glass cover was added to the beaker and placed in an oven at 170°C. After 1 h, the beaker was removed, and the    mixture was poured onto the glass plate. e total mass of the beaker and the adhesive was recorded as m 2 . e leakage loss is calculated according to Formula (1). e specification requires that, for the drainage asphalt mixture, the leakage loss in the leakage test should be ≤0.8%. TPS drainage asphalt mixture and SBS drainage asphalt mixture with basalt fiber content of 0%, 0.15%, 0.25%, and 0.35% were made with 0.5% oil-aggregate ratio in the range of 4%∼6% oilaggregate ratio. e inflection point of the curve in the leakage loss-oil-aggregate ratio diagram was taken as the maximum asphalt content.
In the formula: Δm--loss rate of leakage, %; m 0 --cup quality, g; m 1 --total quality of beaker and asphalt mixture, g.
(2) Leakage Test Results. e results of leakage test are shown in Table 8 and Figure 3. Taking the inflection point of the curve in the leakage loss-oil ratio diagram as the maximum asphalt content, the maximum asphalt content of SBS modified asphalt mixture with basalt fiber content of 0%, 0.15%, 0.25%, and 0.35% is 5.0%, 5.1%, 5.2%, and 5.25%, respectively. e maximum asphalt content of TPS modified asphalt mixture is 4.9%. With the increase of fiber content, asphalt content increases accordingly. e reason is that the huge specific surface area of fiber can become the interface of asphalt infiltration, so as to adsorb asphalt, increase the amount of asphalt, and increase the thickness of asphalt structural film, so the higher the fiber content, the higher the maximum asphalt content of asphalt mixture.
(3) CANTABRO Test. e specific steps of the Scattering loss test are as follows: Marshall specimens were placed in a constant temperature water bath at 20°C and 0.5°C for 20 h.
e specimen was taken out and weighed as m 0 . Put it into the Los Angeles wear testing machine, without steel ball, set the speed of 30∼33 r/min, and the revolution is 300 r. en, the broken specimen was taken out, and the maximum test block in the residual test block was selected for weighing, denoted as m 1 . Calculate the dispersion loss rate, as shown in formula (2). Within the range of 4%-6% of the oil-stone ratio, TPS modified asphalt Marshall specimens and SBS modified asphalt Marshall specimens with 0%, 0.15%, 0.25%, and 0.35% basalt fiber content were prepared with 0.5% of the oil-stone ratio to conduct the dispersion test. e minimum asphalt content takes the inflection point of the curve in the dispersion loss-oil ratio diagram.
(4) Results of Scattering Loss Test. e results of scattering loss test are shown in Table 9 and Figure 4, e maximum asphalt content of SBS modified asphalt mixture with 0%, 0.15%, 0.25%, and 0.35% basalt fiber is 5.0%, 5.1%, 5.2%, and 5.25%, respectively; e minimum asphalt content is 4.8%, 5.0%, 5.1%, and 5.15%, respectively. e maximum asphalt content of TPS drainage asphalt mixture is 4.9%, and the minimum asphalt content is 4.7%. With the increase of fiber content, the amount of asphalt also increases accordingly, because the huge specific surface area of fiber can become the interface of asphalt infiltration, so as to adsorb asphalt, increase the amount of asphalt, and increase the thickness of asphalt structural film. e leakage loss rate and dispersion loss rate of SBS drainage asphalt mixture with basalt fiber are significantly lower than those of SBS drainage asphalt mixture without basalt fiber. With the increase of fiber content, the leakage loss rate and dispersion loss rate show a trend of first decreasing and then increasing. e reason is that after the fiber is mixed with the asphalt mixture, it produces physical infiltration or even chemical bond with  Advances in Civil Engineering 5 the surface active substances in the asphalt. e asphalt is wrapped on the surface of the fiber to inhibit its free flow and reduce the leakage loss and dispersion loss; however, when the fiber content exceeds a certain amount, it is difficult for the fiber to be uniformly dispersed, and it will be intertwined or even agglomerated. e asphalt mixture in the agglomerated part will gather more free asphalt, and the leakage loss and dispersion loss will increase instead.

Determination of Fiber Content.
e test results are shown in Table 10 and  e analysis of the test results shows the following: With the increase of fiber content, the porosity and mineral gap rate decrease accordingly, and the asphalt saturation increases. Because the increase of fiber content will increase the asphalt content and occupy more voids, the porosity and mineral gap rate decrease accordingly, and the asphalt saturation increases. However, the three changes are not significant, because the drainage asphalt mixture is the skeleton void structure, and the gradation type is the decisive factor affecting the void ratio. e fiber content and asphalt content have little effect on it. It can be seen from Figure 8 that Marshall stability increases with the increase of fiber content. When the basalt fiber content is 0.25%, the stability has a peak value of 7.76 kN. e reason is that the high tensile strength of basalt fiber can improve the strength of drainage asphalt mixture, thus improving the stability and the ability to resist deformation. However, when the fiber content is too high, the fiber is difficult to be evenly distributed in the mixture, entangled together, and the fiber cannot give full play to its role. When subjected to load, stress concentration may occur, resulting in local damage and Marshall stability decreases. e stability reaches the peak when the basalt fiber content is 0.25%, and the leakage loss rate and dispersion loss rate are the smallest when the basalt fiber content is 0.25%, indicating that the fiber can play a better role and enhance the performance of the mixture. erefore, 0.25% basalt fiber is selected as the best dosage.

Test Method for Rheological Properties
3.3.1. Dynamic Shear Test. Using dynamic shear rheometer: According to the specification JTG E20-2011, T0628-2011, in the temperature range of 58°C-82°C, the temperature of matrix asphalt, 7% SBS modified asphalt, and 12% TPS modified asphalt was scanned for each increase of 6°C. e control strain mode was selected, and the loading strain was uniformly selected as 10%.
e loading frequency was 10 rad/s, and the sample size was 25 mm × 2 mm. e complex shear modulus G * , phase angle δ, rutting factor G * /sinδ and other parameters of the matrix asphalt before and after aging and the composite modified asphalt before and after aging were tested by dynamic shear rheometer to study the high-temperature performance of the composite modified asphalt.

Flexural Creep Stiffness Test.
Using bending beam rheometer: e BBR test of matrix asphalt, 7% SBS modified asphalt, and 12% TPS modified asphalt at −12°C, −18°C and −24°C was carried out to determine the bending creep stiffness modulus S and creep curve slope m, and the low temperature crack resistance of asphalt was studied.

High-Temperature Stability.
e YLDCX-6 automatic wheel milling machine is used. ree rut boards of fiber-free SBS drainage asphalt mixture, 0.25% basalt fiber content SBS drainage asphalt mixture, and TPS drainage asphalt mixture are formed, respectively, with the volume of 300 mm × 300 mm × 50 mm. en, the YLDCZ-8S rut tester is used, and the test is carried out at 60°C, 42 times/min and 0.7 MPa.

Water Stability
(1) Immersion Marshall Test. Eight standard Marshall specimens of three kinds of drainage asphalt mixtures were formed, respectively, and the residual stability, namely, the ratio of the stability of the specimen soaked for 48 h and 0.5 h at 60°C, was used as the evaluation standard. e larger the value was, the stronger the ability of the mixture to resist water damage was. In this experiment, the DF stability tester was used to measure the stability, and then the residual stability was obtained.
(2) Freeze-aw Splitting Test. Marshall specimens of three kinds of drainage asphalt mixtures were formed in two groups, and the first group was subjected to splitting test after water bathing at 25°C for 2 h. e second group was saturated for 15 min under the condition of 97.3∼98.7 kPa vacuum degree. e specimens were placed in a plastic bag, and 10 mL water was added. e specimens were placed at −18°C for 16 h and then bathed at 60°C for 24 h. Finally, the splitting test was carried out at 25°C for 2 h. Angeles testing machine to rotate 300 revolutions at a speed of 33 r/min. e mass of the specimen was taken out, and the dispersion loss was calculated and compared with the standard dispersion loss.

Low Temperature Crack Resistance.
e low temperature bending test of the beam was used to evaluate the low temperature crack resistance of the drainage asphalt mixture. In other words, the vertical pressure was applied in the middle of the beam until the beam was damaged. e ability of the mixture to resist deformation under lowtemperature conditions was simulated. e evaluation indexes were flexural tensile strength, maximum flexural tensile strain, and flexural stiffness modulus. e rutting plates of SBS drainage asphalt mixture with basalt fiber, TPS drainage asphalt mixture, and nonfiber SBS drainage asphalt mixture were cut into small beams with a volume of 30 mm × 35 mm × 250 mm, respectively. e asphalt mixture multifunctional dynamic test system was used to load at the midpoint under the conditions of −10°C of test temperature and 50 mm·min −1 of loading speed, and the required data for the test were calculated.

Test Method for Drainage Performance.
e basic steps of seepage test are as follows: the asphalt mixture specimen was formed by wheel milling method. e steel ring was placed in the central position of the specimen, and the lines were marked along the inner ring and the outer ring by chalk. Take off the steel ring, the two-ring clamp part with waterproof putty; '/'mm for sealing treatment. Place the pavement water seepage meter at the measuring point and press down the base of the water seepage meter to enhance the water tightness and prevent water from flowing out of the gap or other gap between the water seepage meter and the sealing material. Exhaust the air in the water meter and fill the water, open the switch, and when the water surface drops to 100 mL, start timing. When the water surface drops to 500 mL, stop counting and calculate the seepage coefficient.

Scanning Electron Microscope Test. JSM-7500F
scanning electron microscope (SEM) was used to observe the microscopic characteristics of splitting failure of basalt fiber SBS drainage asphalt mixture and fiber-less SBS drainage asphalt mixture and the distribution of basalt fiber in the mixture. e length, width, and height of the specimen are 2 cm × 2 cm × 1 cm, and the automatic magnetron sputtering instrument is used to spray gold for 15 s at 40 mA current, so that the specimen has enough conductivity.

Determination of Modifier Dosage.
e comparison results of main performance indexes are shown in Table 11. It can be seen from Table 11 that the decrease of penetration of the two modified asphalts indicates that the viscosity of asphalt increases and the road performance is improved. e low temperature ductility of modified asphalt has been further improved. SBS modifier exceeds the modification effect of TPS modifier, indicating that SBS modified asphalt has better low temperature crack resistance. e modified asphalt with high dynamic viscosity at 60°C can form thick asphalt film and has good adhesion performance, thus improving the water stability and durability of the mixture.

Dynamic Shear Test.
e test results are shown in Figures 9 and 10, and the analysis in Figures 9 and 10 shows that, with the increase of temperature, the phase angle of matrix asphalt increases, indicating that the proportion of viscoelastic components has changed, and the matrix asphalt is transformed from elasticity to viscosity. However, SBS modified asphalt showed a trend of first increase and then decrease, because with the increase of temperature, the activity of modifier increased with the increase of temperature, which increased the proportion of elastic components in modified asphalt. e phase angle of TPS modified asphalt was lower than that of SBS modified asphalt, indicating that the proportion of elastic components was large, the ability to restore deformation was stronger, and the ability to resist high temperature deformation was stronger. Peng et al. studied the performance of modified lignocellulose and SMA-13 asphalt mixture and concluded that when the yield of modified lignocellulose ranged from 0.3% to 0.5%, the rutting resistance was the best [30]. In this experiment, with the increase of temperature, the complex shear modulus and rutting factor of the three asphalts show a decreasing trend, indicating that the antirutting deformation ability is reduced. Meanwhile, because the rutting factor of TPS modified asphalt is higher than that of SBS modified asphalt, TPS modified asphalt has better rutting resistance.

Flexural Creep Stiffness Test.
e test results are shown in Figures 11 and 12; by analyzing Figures 11 and 12, it can be seen that the stiffness modulus of the three kinds of asphalt increases with the decrease of temperature, which reflects that the brittleness of asphalt increases with the  energy required for material failure, and the better the crack resistance, and the SBS modified asphalt has better low temperature crack resistance. With the decrease of temperature, the creep rate of three kinds of asphalt is also reduced. e maximum creep rate of SBS modified asphalt is m, and the stiffness modulus S changes faster with time. Under low temperature environment, the stiffness modulus S value decreases rapidly, which reduces the possibility of cracking of drainage asphalt pavement. SBS modified asphalt has better low temperature crack resistance. erefore, SBS modified asphalt has the minimum stiffness modulus, the maximum creep rate, and the best low temperature crack resistance at the same temperature.  Table 12.

Analysis on Road
e deformation of basalt fiber SBS drainage asphalt mixture is the smallest, and the DS value is increased by 0.5% and 14.3%, respectively, compared with TPS drainage asphalt mixture and nonfiber SBS drainage asphalt mixture. It shows that adding fiber under high temperature can improve the stability of the material, mainly reflected in two aspects: firstly, the reason of rutting is largely due to the decrease of asphalt viscosity under high temperature conditions, showing plastic characteristics. e    addition of basalt fiber will adsorb more free asphalt, and the proportion of structural asphalt with strong adhesion will increase. erefore, the adhesion of the mixture is enhanced, and the high temperature stability of the drainage asphalt mixture is improved; secondly, the fibers are evenly distributed in the mixture and overlap with each other to form a fiber skeleton network, which plays a role of reinforcement, restricting the free movement of aggregates and playing the role of hooping. us, the antideformation ability of the mixture is improved, so as to improve the high-temperature stability of the drainage asphalt mixture. Studies have shown that when the basalt content reaches 0.4%, the high temperature stability of the 6 mm chopped basalt fiber mixture is the best, which is 1.8 times that of the ordinary asphalt mixture [31].

Water Stability.
Relevant research shows that the water stability of 6 mm fiber asphalt mixture with 0.2% content is the best [31]. e water stability test results of three asphalt mixtures in this test are shown in Tables 13-15. Tables [13][14][15] show that the three performances of 0.25% basalt fiber SBS drainage asphalt mixture are the best. e residual stability, freeze-thaw splitting strength ratio, and immersion dispersion loss of 0.25% basalt fiber SBS drainage asphalt mixture are 2.7%, 5.6%, and 4.9% higher than those of TPS drainage asphalt mixture, respectively, and 8.6%, 8.5%, and 8.5% higher than those of nonfiber SBS drainage asphalt mixture. e reason is that, similar to the high temperature stability of fiber reinforced drainage asphalt mixture, the addition of fiber increases the proportion of structural asphalt, the adhesion between asphalt and aggregate is enhanced, and the erosion of water is weakened. In addition, the network structure formed by fiber in the mixture increases the strength of the mixture. In addition, the raw material test shows that the moisture absorption of basalt fiber is poor, which can avoid its expansion at the interface and improve the water stability of drainage asphalt mixture.

Low Temperature Crack
Resistance. Low temperature crack resistance test results are shown in Table 16; the analysis in Table 16 shows that the flexural stiffness modulus of basalt fiber SBS drainage asphalt mixture is the smallest, which is 5.7% and 10.2% lower than that of fiber-less SBS drainage asphalt mixture and TPS drainage asphalt mixture, respectively. is shows that the greater the energy required for material failure, the better the crack resistance at low temperature. e maximum flexural tensile strain of basalt fiber SBS drainage asphalt mixture is the largest, which is 9.5% and 15.3% higher than that of nonfiber SBS drainage asphalt mixture and TPS drainage asphalt mixture, respectively. It shows that the higher the strain is, the better the resistance to low temperature deformation is. Cheng et al. studied the effect of basalt fiber content on the pavement performance of large-porosity asphalt mixture and found that basalt fiber could improve the splitting tensile strength of large-porosity asphalt mixture before and after freezing and thawing, indicating that basalt fiber had excellent lowtemperature crack resistance [32]. e low temperature crack resistance of basalt fiber SBS drainage asphalt mixture is the best, and TPS drainage asphalt mixture is the worst. e low temperature crack resistance of SBS modified asphalt is better than that of TPS modified asphalt. Basalt fiber SBS drainage asphalt mixture has the best low temperature crack resistance. Analyzing the reasons, the fibers overlap with each other in the mixture space to form a fiber grid.
Under low temperature conditions, it plays a role of tackifying, inhibits the flow of free asphalt, and enhances the bonding with aggregate. e elastic modulus of fiber is high, and the tensile strength is large, which can improve the overall performance of the mixture. In addition, fiber grid can spread the pavement load inside the mixture, reduce stress concentration, and prevent pavement cracking.

Connecting Void.
e voids of drainage asphalt mixture include connected voids, semiconnected voids, and closed voids, as shown in Figure 8. e semiconnected voids can store water but cannot drain. e closed voids can neither store water nor drain. Only the connected voids can play the role of drainage. erefore, it is extremely important to study the connected voids for drainage asphalt pavement. e analysis of the test results is shown in Table 17. e void ratios of the three kinds of drainage asphalt mixtures are maintained at about 20%, which meets the requirements of the initial void ratio of the drainage pavement. e connectivity porosity is above 15%, so the three drainage asphalt mixtures all meet the requirements of drainage function of drainage pavement.

Analysis of Seepage Test.
e seepage test results are shown in Table 18. e analysis of the test results shows that the seepage coefficient of basalt fiber drainage asphalt mixture is the smallest. e reason for the analysis is that the incorporation of fibers reduces the void ratio of the mixture. At the same time, the adsorption of fibers on asphalt increases the amount of asphalt and decreases the void ratio. However, the main factor affecting the void ratio is the gradation type, so the number of fibers and asphalt have little effect on the results, which also meets the specification requirements and has good drainage performance.

Scanning Electron Microscope Analysis
(1) Analysis on Strengthening Effect of Bonding Interface between Fiber and Asphalt. e OGFC-13 asphalt mixture belongs to the skeleton void structure, and the interlocking force of mineral particles is not strong, mainly relying on the bonding effect of binder. In related studies, it is proposed that the combination mode between fiber and asphalt mixture is mainly mechanical connection and infiltration adsorption. Since the fiber surface is not smooth but has a certain roughness, convex and concave, the pits on the

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Advances in Civil Engineering surface of asphalt and fiber form a more compact combination [33]. It can be seen from Figure 13 that the mineral aggregate in the nonfiber SBS drainage asphalt mixture is not closely bonded to the asphalt, and there are a large number of voids. erefore, with the increase of temperature and the erosion of water, the mineral aggregate is easy to peel off from the asphalt surface, resulting in rutting, pits, and other damage. e fiber diameter is small, and the mixed mixture has a huge specific surface area. e fiber surface is adsorbed by a large amount of asphalt, and the root is closely bonded with the asphalt mixture. is shows that the infiltration between fiber and asphalt liquid is great, and the bonding degree of the interface between the two is significantly greater than that between the mineral aggregate of nonfiber asphalt mixture and asphalt. Figure 14 shows that fiber and mixture are combined by mechanical connection and infiltration adsorption. Basalt fiber has a certain roughness and unevenness. Asphalt phase extends to the pits on the surface of fiber phase, forming a closer combination. When asphalt phase      contacts with fiber, it is surface contact, resulting in the effect equivalent to mechanical anchor sum. It has a large bite force and improves the high temperature stability of drainage asphalt mixture by improving the bond strength. Transition layer refers to the structural asphalt layer, and the transition layer between free asphalt and fiber can connect two phases. ere are two forms of asphalt in the mixture. One is the constrained structural asphalt, and the other is the free asphalt without contact with the entity. e constrained structural asphalt has stronger bonding force. e adsorption of fiber makes free asphalt transform into transition layer structure asphalt at the contact point of the two. e fiber with large specific surface area will form a large number of transition layers in the mixture, and the proportion of structural asphalt with higher cohesive force increases.
erefore, the addition of fiber can improve the high and low temperature stability and water stability of drainage asphalt mixture. e incorporation of basalt fiber changes the effect of each phase interface of drainage asphalt    (2) Effect of Fiber on Reinforcement and Crack Resistance of Drainage Asphalt Mixture. It can be seen from Figure 15 that the splitting failure surface of fiber-free SBS drainage asphalt mixture has many cracks and different stripping levels. e mineral material is in a state of separation, and the connection is extremely weak. e microscopic picture of drainage asphalt mixture with basalt fiber is shown in Figure 16.
e main failure mode of asphalt mixture in use is shear failure, which starts from the internal voids of asphalt mixture and spreads along the original voids, especially the interface between asphalt and mineral [33]. e basalt overlaps vertically and horizontally in the mixture to form a spatial network structure. When the asphalt pavement is subjected to load, the spatial network structure can transfer stress and reduce stress concentration, which is similar to the role of reinforcement in reinforced concrete. It can also inhibit the free movement of particles, play a 'hoop' role in the mixture, and improve the overall mechanical properties of drainage asphalt pavement. It can be seen from the photographs of the fiber fracture that the fiber is interspersed in the asphalt mixture, and the root is absorbed by the asphalt and buried in the internal of the asphalt mixture, indicating that the basalt fiber and the asphalt mixture have strong adhesion and crack resistance.

Conclusion
(1) Compared with TPS drainage asphalt mixture and nonfiber SBS drainage asphalt mixture, basalt fiber SBS drainage asphalt mixture can better improve the high temperature stability of drainage asphalt mixture. 0.25% basalt fiber SBS drainage asphalt mixture has the best three properties, indicating that its water stability is the best; the maximum bending strain of basalt fiber SBS drainage asphalt mixture is the largest, which shows that its resistance to low temperature deformation is better than the other two kinds of drainage asphalt mixture. (2) e optimum asphalt content of BS drainage asphalt mixture with basalt fiber content of 0%, 0.15%, 0.25%, and 0.35% is 4.9%, 5.05%, 5.15%, and 5.2%, respectively. When the content of basalt fiber is 0.25%, the stability reaches the peak, and the leakage loss rate and the dispersion loss rate reach the minimum. erefore, 0.25% is selected as the optimal content of basalt fiber. (3) e high temperature performance, water stability, low temperature performance, and drainage performance of 0.25% basalt fiber SBS drainage asphalt mixture can meet the specification requirements, and the performance is better. Compared with no fiber SBS drainage asphalt mixture and TPS drainage asphalt mixture, the dynamic stability, residual stability, and freezethaw splitting strength are improved. Dip loss and bending stiffness modulus decrease. e connectivity porosity of basalt fiber SBS drainage asphalt Marshall specimen is 15.97%, and the permeability coefficient is 3809.5 mL/min, which meets the requirements of the specification. erefore, SBS drainage asphalt mixture with basalt fiber has good performance and can be applied in drainage pavement. (4) e root of basalt fiber mixed with asphalt mixture is closely bonded with the mixture, and the bonding degree of the interface between basalt fiber and asphalt mixture is significantly greater than that of the mineral aggregate and asphalt mixture without basalt fiber, which has a large bite force and improves the bonding strength, indicating that the infiltration effect between basalt fiber and asphalt is good; and the bonding interface bonding degree of the two is significantly greater than that of the fiber-free asphalt mixture mineral and asphalt joint. e formation of network structure in the mixture inhibits the further diffusion of cracks and improves the high and low temperature performance and water stability of drainage asphalt mixture.

Data Availability
Some or all data, models, or code that support the findings of this study are available from the corresponding author upon reasonable request. Advances in Civil Engineering 15