A method for preparing a pervious asphalt mixture

Abstract

The application relates to a preparation method and device of water-permeable asphalt mixture, which comprises the following steps: S1, heating coarse materials to 170-190 DEG C and performing high-frequency vibration; S2, cooling the coarse materials to 150-160 DEG C, spraying atomized asphalt and fine materials, and stirring; S3, continuously stirring, reducing the temperature of the mixed part to 130-140 DEG C, introducing 5%-8% nano calcium carbonate modifier, and stirring again. Through linkage of multi-stage temperature regulation and stirring, the application avoids asphalt aging and insufficient mixing, improves overall quality, solves the problem of asphalt aging or insufficient mixing caused by single temperature setting, guarantees suitable temperatures required by material reactions in each stage, ensures uniform mixing of components through continuous stirring, and significantly improves the comprehensive performance of the mixture and the product qualification rate.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of asphalt mixture preparation technology, in particular to a preparation method of water permeable asphalt mixture. BACKGROUND

[0002] As an open-graded material with skeleton and void structure, water permeable asphalt mixture originated in Europe in the mid-20th century and was initially used to solve road drainage and noise reduction problems. With the acceleration of urbanization, this material has been widely used worldwide due to its ecological advantages such as alleviating urban waterlogging and replenishing groundwater sources. In recent years, research on related technologies has focused on optimizing material components and improving preparation processes to enhance mechanical properties and durability. Currently, the industry generally uses the basic preparation process of heating-mixing-molding to achieve the designed void ratio by controlling parameters such as coarse aggregate gradation and asphalt content, but there is still room for improvement in the uniformity of material mixing and temperature coordination control.

[0003] The existing water permeable asphalt mixture preparation technology has the following shortcomings: first, coarse aggregates are prone to agglomeration after heating due to interparticle forces, and traditional mixing methods cannot effectively break up the agglomerates, resulting in uneven distribution of void structures; second, the addition of asphalt and fine aggregates is mostly done by synchronous pouring, and asphalt can quickly wrap around local particles at high temperatures, forming oil agglomerates or dry spots; third, the modifier is mostly added at the end of mixing, and it is difficult to achieve molecular dispersion due to the influence of material viscosity, which weakens its performance enhancement effect on the mixture. In addition, temperature control is mostly set in a single interval, and there is no gradient adjustment for the reaction characteristics of different materials, resulting in asphalt aging or insufficient mixing. SUMMARY

[0004] To overcome the shortcomings of the prior art, the purpose of the present application is to provide a preparation method of water permeable asphalt mixture, which can fully mix the materials and reduce agglomeration.

[0005] The above-mentioned purpose of the present application is achieved by the following technical solutions:

[0006] A preparation method of water permeable asphalt mixture, the method comprising: step S1, heating coarse aggregates to 170-190 DEG C and performing high-frequency vibration; step S2, cooling the coarse aggregates to 150-160 DEG C while spraying atomized asphalt and fine aggregates and stirring; step S3, continuously stirring and reducing the temperature of the mixed part to 130-140 DEG C, and introducing 5-8% of nano calcium carbonate modifier.

[0007] As a preferred embodiment of the present application, in step S1, the high-frequency vibration is achieved by a piston mechanism arranged obliquely, which comprises a piston rod and a sleeve, the sleeve is arranged obliquely to the horizontal plane, the sleeve is hollow, the upper end of the sleeve is the coarse material inlet end, the side wall of the sleeve is provided with a blanking hole, the piston rod blocks the lower end of the sleeve, the piston rod reciprocates along the sleeve to open or close the blanking hole, and the high-frequency vibration is generated by the periodic reciprocating movement of the piston rod.

[0008] As a preferred embodiment of the present application, the periodic reciprocating movement of the piston rod forms a temporary gap structure between the coarse material particles.

[0009] As a preferred embodiment of the present application, in the reciprocating movement of the piston rod, when the piston rod moves upward along the sleeve, the rod body of the piston rod blocks the blanking hole, and the top end of the piston rod collides with the coarse material in the sleeve to generate a first vibration wave, and at the same time, a positive pressure is formed in the sleeve due to the upward movement of the piston rod.

[0010] When the piston rod moves downward along the sleeve, the rod body of the piston rod is away from the blanking hole, and the top end of the piston rod collides with the bottom of the sleeve to generate a second vibration wave, and at the same time, a negative pressure is formed in the sleeve due to the downward movement of the piston rod.

[0011] The first vibration wave and the second vibration wave form superposition in the sleeve, and the airflow impact generated by the positive and negative pressure difference makes the coarse material produce spiral rolling displacement under the synergistic action of vibration force, gravity component and air pressure thrust.

[0012] As a preferred embodiment of the present application, the opening time of the blanking hole is 1.5 to 2 times the closing time; the single stroke of the piston rod is 15 to 25 mm.

[0013] As a preferred embodiment of the present application, in step S2, the cooling process of the coarse material and the operation of introducing the atomized asphalt and the fine material into the stirring device are completed in the stirring device, the upper end of the stirring device is connected with the blanking hole, the lower end of the stirring device is provided with a feeding port, the atomized asphalt is injected into the stirring device from the feeding port to form a convection with the coarse material, and the fine material is sent into the stirring device from the blanking hole after the coarse material is discharged.

[0014] As a preferred embodiment of the present application, a mixing assembly is arranged in the stirring device, the coarse material falls into the stirring device from the blanking hole in the reciprocating movement of the piston rod, the atomized asphalt is injected into the stirring device from the feeding port, and the fine material falls into the stirring device from the blanking hole, and in this process, the mixing assembly continuously rotates to mix the materials in the stirring device.

[0015] As a preferred embodiment of the present application, in step S3, the feeding port is closed when the nano calcium carbonate modifier is introduced, the piston rod stops moving in the state that the material falling hole is open, the nano calcium carbonate modifier enters the stirring device from the sleeve, and the mixing assembly continues to rotate.

[0016] As a preferred embodiment of the present application, the mixing assembly comprises a material turning shaft and a plurality of stirring blade assemblies, each of the stirring blade assemblies is connected to the side wall of the material turning shaft and is spaced apart along the axis direction of the material turning shaft to form multiple layers.

[0017] A permeable asphalt mixture device for realizing the preparation method of the permeable asphalt mixture.

[0018] In summary, the beneficial technical effects of the present application are as follows:

[0019] 1. The present application solves the problem of coarse material aggregation by the cooperation of coarse material heating and high-frequency vibration, and improves the uniformity of the skeleton. In step S1, the coarse material is heated to 170-190 DEG C and subjected to high-frequency vibration. The vibration energy is used to break the force between the coarse material particles, avoid the local dense area formed by the aggregation of the coarse material in the traditional heating process, and form a uniform temporary gap structure between the coarse material particles. The problem of uneven gap distribution caused by the easy aggregation of the coarse material after heating is solved, and a stable skeleton foundation is provided for the subsequent filling of asphalt and fine material, ensuring that the overall void ratio of the mixture meets the design requirements.

[0020] 2. The present application optimizes the asphalt wrapping effect by combining gradient cooling and the incorporation of atomized asphalt, and avoids local defects. In step S2, the coarse material is cooled to 150-160 DEG C, and atomized asphalt and fine material are sprayed and stirred at the same time. Compared with the traditional high-temperature synchronous pouring method, the atomized asphalt can be more uniformly dispersed on the surface of the coarse material. In combination with the suitable temperature after cooling, the problem of oil clumps or dry spots caused by the rapid viscosity of asphalt due to high temperature is solved. The asphalt is more uniformly coated on the surface of the aggregate, and the mechanical property consistency of the mixture is improved.

[0021] 3. The present application promotes the dispersion of the modifier and strengthens the reinforcing effect by the cooperation of low-temperature environment and continuous stirring. In step S3, the mixture is cooled to 130-140 DEG C, 5-8% of the nano calcium carbonate modifier is introduced, and stirring is performed again. The temperature interval reduces the viscosity of the material, so that the modifier is more easily penetrated and dispersed into the mixture under the action of continuous stirring, avoiding the uneven dispersion caused by the viscosity of the material when the traditional modifier is introduced at one time. The problem of difficult molecular dispersion of the modifier is solved, the reinforcing effect of the modifier on the asphalt mixture is enhanced, and the durability and anti-deformation ability are improved.

[0022] 4. The present application avoids asphalt aging and insufficient mixing through the linkage of multi-stage temperature regulation and stirring, improves overall quality, and solves the problem of asphalt aging or insufficient mixing caused by single temperature setting through the coordinated operation of gradient temperature process and each stage of stirring, which not only ensures the appropriate temperature required for material reaction in each stage, but also ensures uniform mixing of each component through continuous stirring, significantly improves the comprehensive performance of the mixture and the product qualification rate. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 A flowchart of the preparation method of the porous asphalt mixture.

[0024] Figure 2 A flowchart of the method for forming a temporary gap structure between coarse materials.

[0025] Figure 3 A structural schematic diagram of the porous asphalt mixture device provided by the present application;

[0026] Figure 4 A sectional view of the porous asphalt mixture device provided by the present application;

[0027] Figure 5 A structural schematic diagram of the position of the turnover vortex blade in the porous asphalt mixture device provided by the present application;

[0028] Figure 6 A structural schematic diagram of the position of the parallel hopper in the porous asphalt mixture device provided by the present application;

[0029] Figure 7 An internal sectional view of the position of the parallel hopper in the porous asphalt mixture device provided by the present application;

[0030] Figure 8 An internal exploded structural schematic diagram of the position of the parallel hopper in the porous asphalt mixture device provided by the present application;

[0031] Figure 9 An exploded structural schematic diagram of the position of the piston rod in the porous asphalt mixture device provided by the present application.

[0032] Reference numerals: 101. Mixing device; 102. Insulation shell; 103. Constant temperature plate; 104. Feed inlet; 105. Shaft frame; 106. Top cover; 107. First discharge port; 108. Sliding seal ring; 109. Tilting motor; 110. Tilting shaft; 111. Tilting vortex blade; 112. Mixing rod; 113. Tilting actuating blade; 201. Second discharge port; 202. Support outer cylinder; 203. Protective shell; 204. Support ring; 205. Connecting column; 206. Distributing port; 207. Converging hopper; 208. Adjusting bin; 209. Feeding hopper; 301. Sleeve; 302. Connecting rotor; 303. Guide hole; 304. Piston rod; 305. Extension cylinder; 306. Hexagonal slide groove; 307. Elastic baffle membrane; 308. Buffer ring; 309. Guide slide column; 401. Baffle plate; 402. Reinforcing ring; 403. Sealing ring; 404. Guide rod; 405. Mounting plate; 406. Premix motor; 407. Hexagonal slider; 408. Push-pull guide frame; 409. Threaded cylinder; 410. Slide cylinder; 411. Discharge motor; 412. Threaded push rod. Detailed Implementation

[0033] The present application will be further described in detail below with reference to the accompanying drawings.

[0034] like Figure 1 As shown, a method for preparing permeable asphalt mixture is presented. The core of this method is to achieve efficient dispersion and uniform mixing of materials through a three-step gradient treatment. The specific process is as follows: First, a coarse material pretreatment stage is carried out. Coarse materials with particle size that meet the design requirements are selected and put into a heating device for heating. Then, a piston mechanism is introduced for vibration treatment.

[0035] The heating system uses thermocouples to monitor and precisely control the temperature of the coarse material in real time within the range of 170℃ to 190℃. This temperature range reduces the adsorption force on the surface of the coarse material and prevents performance degradation due to high temperatures. The material is then subjected to vibration via a piston mechanism, with the vibration duration adjusted according to the amount of coarse material. Under the action of periodic mechanical force, the coarse material overcomes the van der Waals forces and friction between particles, breaking down the naturally occurring agglomeration and forming a preliminary dispersed, loose structure, laying the foundation for subsequent mixing with other materials.

[0036] Next, into the mixing phase, the pretreated coarse material is transported to the stirring device 101 through the first drop port 107, and the stirring device 101 stirs the coarse material to reduce the temperature gradient of the coarse material to 150-160°C. In this temperature range, the construction viscosity of asphalt is relatively optimal, which can avoid the asphalt from flowing due to too high temperature or uneven coating due to too low temperature. The molten asphalt is heated to 160-180°C and atomized into 5-10 μm droplets by the high-pressure atomizing nozzle in the prior art, and sprayed into the stirring device 101. After the coarse material is sprayed, the fine material is added. In this process, the asphalt continues to be sprayed and the stirring device 101 continues to stir. The stirring device 101 makes the atomized asphalt, fine material and coarse material fully contact under the action of shear force, wherein the asphalt droplets uniformly coat the surface of the coarse material, and the fine material fills the gap between the coarse material particles to form a preliminary skeleton-filling structure.

[0037] Finally, the modified reinforcement stage, the stirring device 101 is kept running, and the material temperature is further reduced to 130-140°C. This temperature can reduce the overall viscosity of the mixture and create favorable conditions for the dispersion of the modifier. At this time, the nano calcium carbonate modifier is added. The stirring speed of the stirring device 101 is increased to 80-120 r / min, and the nano calcium carbonate is uniformly dispersed in the asphalt film by higher shear rate to form a stable composite system with asphalt. The nano particles can fill the gap between asphalt molecules and enhance the interfacial adhesion between asphalt and coarse material and fine material. After continuous stirring for 5-10 min, the entire preparation process is completed, and the obtained mixture can be directly used for subsequent molding operations.

[0038] Further, the high-frequency vibration mechanism is realized by a piston mechanism arranged obliquely, which includes a piston rod 304 and a sleeve 301. The sleeve 301 is arranged obliquely at an angle of 15-30° with respect to the horizontal plane. This angle design facilitates the natural sliding of the coarse material under the action of the gravity component and forms a combined motion trajectory with the vibration force. The sleeve 301 is hollow, and its upper end is a coarse material inlet end for continuously supplying coarse material to be processed. The side wall of the sleeve 301 is provided with a drop hole, and the specific size of the drop hole is determined according to the maximum particle size of the coarse material to ensure that the qualified coarse material can smoothly pass through the drop hole and avoid blockage.

[0039] The piston rod 304 is assembled at the lower end of the sleeve 301, and the rod body diameter of the piston rod 304 is matched with the gap between the inner wall of the sleeve 301 to ensure that the piston rod 304 can smoothly reciprocate along the sleeve 301 and form an effective seal. The reciprocating motion of the piston rod 304 directly controls the opening and closing of the drop hole. Specifically, when the piston rod 304 moves upward along the sleeve 301, the rod body part will block the drop hole of the side wall, so that the coarse material cannot fall temporarily. When the piston rod 304 moves downward, the rod body part is separated from the drop hole area, and the through hole is completely exposed to allow the coarse material to pass through.

[0040] The high-frequency vibration is generated from the periodic reciprocating movement of the piston rod 304: when the piston rod 304 moves upward to the limit position, the top end of the piston rod 304 collides rigidly with the coarse material in the sleeve 301, generating a first beam of vibration waves; when the piston rod 304 resets downward to the lowest point, the bottom end of the piston rod 304 collides with the baffle plate 401 at the bottom of the sleeve 301, generating a second beam of vibration waves. The two beams of vibration waves propagate axially in the inclined sleeve 301 and superimpose to form a high-frequency vibration field. Such vibration not only breaks the cohesion between coarse material particles, but also causes relative displacement between particles, which, combined with the periodic opening and closing of the material falling hole, realizes the dispersion and grading screening of the coarse material. The oversized particles that do not pass through the material falling hole will be further broken under the action of continuous vibration, while the qualified particles will pass through the material falling hole into the subsequent processing link.

[0041] Further, the periodic reciprocating movement of the piston rod 304 along the sleeve 301 produces continuous mechanical disturbance to the coarse material in the sleeve 301. This disturbance directly acts on the coarse material particles, changes the contact state between the particles, and further forms a temporary gap structure with a specific temporary gap ratio. The temporary gap structure referred to herein is the overall structure formed by the gaps between the particles after the particles are dispersed and arranged under the action of vibration, and the temporary gap ratio is the ratio of the total volume of all gaps in the structure to the total volume of the coarse material particles, which directly reflects the dispersion degree and arrangement looseness of the coarse material particles.

[0042] The reciprocating movement of the piston rod 304 can form such a temporary gap structure, which is mainly due to the transmission of vibration energy to the coarse material particles during the movement of the piston rod 304. When the piston rod 304 moves upward, the rod body of the piston rod 304 extrudes the coarse material, and the collision between the coarse material and the top end of the sleeve 301 generates vibration waves, which push the particles upward and separate from each other; when the piston rod 304 moves downward, the rod body and the bottom of the sleeve 301 generate reverse vibration waves, and the particles are redistributed under the combined action of gravity, impact force and vibration waves. In this process, the cohesion and friction between the particles are overcome by the vibration energy, and the originally agglomerated particles are dispersed to form uniformly distributed gaps.

[0043] As Figure 2As shown, during the periodic reciprocating movement of the piston rod 304 along the sleeve 301, the interaction between the piston rod 304 and the structure of the material dropping hole and the inside of the sleeve 301 forms a multi-dimensional material disturbance mechanism. When the piston rod 304 moves upward, the rod body gradually passes through the material dropping hole of the side wall of the sleeve 301, and finally completely blocks the material dropping hole to block the coarse material falling channel; in this process, the top end of the piston rod 304 collides rigidly with the coarse material in the sleeve 301, and the mechanical energy generated by the collision spreads in the form of elastic waves in all directions, forming a first vibration wave, which spreads along the inclined direction of the sleeve 301 and can directly break the agglomeration force between the coarse material particles. At the same time, the coarse material is added in batches into the sleeve 301 and blocks the upper end of the sleeve 301 to form a sealed space. Since the piston rod 304 moves upward to compress the space in the sleeve 301, and the material dropping hole is temporarily closed, a small amount of gas leaks between the piston rod 304 and the inner wall of the sleeve 301, but the air in the sleeve 301 is still compressed to form a positive pressure of 0.02 MPa to 0.05 MPa. The positive pressure airflow penetrates along the gap between the coarse material particles, further promoting particle separation.

[0044] When the piston rod 304 moves downward, the piston rod 304 uncovers the material dropping hole, and the material dropping hole is completely opened to allow the coarse material to pass through; at this time, the piston rod 304 collides with the bottom of the sleeve 301, generating a second vibration wave with a frequency similar to the movement period of the piston rod 304, and the propagation direction of the second vibration wave is opposite to that of the first vibration wave, forming a wave peak superposition area in the middle of the sleeve 301. At the same time, the downward movement of the piston rod 304 suddenly expands the space in the sleeve 301, forming a negative pressure of -0.01 MPa to -0.03 MPa. The negative pressure sucks in external air through the material dropping hole, forming an upward airflow disturbance, which alternately impacts with the downward airflow in the positive pressure stage.

[0045] The superposition of the first vibration wave and the second vibration wave in the sleeve 301 forms a standing wave effect, and the energy concentration area at the wave crest of the standing wave can make the coarse material particles obtain greater vibration acceleration; and the periodic airflow impact generated by the positive and negative pressure difference gives the particles an axial thrust component. Since the sleeve 301 itself is inclined to the horizontal plane, the coarse material has a downward sliding tendency under the action of the gravity component in the inclined direction. The vector superposition of the above-mentioned vibration force, air pressure thrust and gravity component finally makes the coarse material particles roll in a spiral shape along the inner wall of the sleeve 301, which can not only avoid the local accumulation of particles caused by single direction vibration, but also ensure the uniformity of the temporary gap structure through continuous inter-particle friction and collision, thereby creating favorable conditions for the subsequent filling of fine materials and asphalt.

[0046] The opening time and the closing time of the blanking hole are set in a ratio of 1.5 to 2 times during the reciprocating movement of the piston rod 304. The ratio design is based on the synergistic requirements of coarse material falling and vibration dispersion: when the blanking hole is opened, the coarse material dispersed by high-frequency vibration can continue to fall under the action of the gravity component force and the gas pressure thrust. The longer opening time ensures the stability of the material falling amount per unit time, avoiding material accumulation due to too short opening time. Although the closing time is short, it can generate strong vibration waves through rigid collision during the upward movement of the piston rod 304, further breaking the secondary agglomeration of coarse materials and laying a foundation for uniform dispersion for the next opening and blanking.

[0047] The single stroke of the piston rod 304 is set to 15mm~25mm, which is verified by multiple tests. If the stroke is too small, the impact force of the piston rod 304 and the bottom of the sleeve 301 is insufficient, the second vibration wave energy is weak, and it is difficult to drive the coarse material with large particle size to produce effective rolling. If the stroke is too large, not only will it cause large fluctuations in the gas pressure in the sleeve 301, but it may also exacerbate equipment wear due to excessive friction between the piston rod 304 and the inner wall of the sleeve 301, and cause the coarse material to bounce too much and deviate from the falling trajectory. The stroke of 15mm~25mm can ensure that the standing wave energy formed by the superposition of the two vibration waves is moderate, which is sufficient to make the coarse material roll uniformly along the spiral trajectory, and can avoid material splashing through controllable gas pressure difference, ultimately achieving the balance between vibration dispersion and stable blanking.

[0048] Further, the cooling process of the coarse material and the operation of introducing atomized asphalt and fine material are completed inside the stirring device 101. The upper end of the stirring device 101 is connected to the sleeve 301 through a blanking port, and a screen is installed in the blanking port to form a plurality of blanking holes. When the coarse material enters the stirring device 101 from the blanking hole, the initial temperature is maintained at 170℃~190℃, and the temperature gradually approaches 150℃~160℃ after stirring in the stirring device 101.

[0049] A feed inlet 104 is provided on the lower end side wall of the stirring device 101, and a high-pressure atomizing nozzle is installed at the feed inlet 104. The nozzle is connected to an asphalt heat preservation tank through a heat preservation pipeline. The asphalt is atomized into liquid droplets of 5μm~10μm under the action of a pressure of 0.2MPa~0.3MPa, and is injected upward into the inside of the stirring device 101 from the feed inlet 104. Since the coarse material falls in the vertical direction from the upper end of the stirring device 101, the injection direction of the atomized asphalt is opposite to the falling direction of the coarse material, and the two form a strong convection in the middle part of the stirring device 101, so that the atomized asphalt can uniformly contact the surface of the coarse material.

[0050] The addition of fine materials is carried out in a step-by-step manner. When the discharge hole stops discharging coarse materials, fine materials are transported into the piston mechanism and into the mixing device 101. The fine materials mix with the coarse materials that have been initially coated with asphalt, avoiding the premature addition of fine materials that can cause local accumulation or premature wrapping by asphalt to form clumps. This step-by-step convection mixing method not only improves the uniformity of the coating by utilizing the dispersion of atomized asphalt, but also ensures the accuracy of the fine materials filling the gaps between coarse materials by the late addition of fine materials, laying a uniform material basis for the subsequent incorporation of modifiers.

[0051] Further, the mixing assembly is provided inside the mixing device 101. When the coarse materials continuously fall into the mixing device 101 from the discharge hole in the side wall of the sleeve 301 under the periodic reciprocating motion of the piston rod 304, the mixing assembly is already in the starting state. At this time, the coarse materials enter the upper inlet of the mixing device 101 and spread to the lower part of the device under the action of their own gravity and the initial agitation of the mixing assembly. At the same time, the atomized asphalt enters through the feed inlet 104 at the lower end of the mixing device 101 in a high-pressure jetting manner, with the jetting direction opposite to the falling direction of the coarse materials. Under the stirring action of the mixing device 101, a convection impact effect is formed, enabling the atomized asphalt particles to quickly contact the surface of the coarse materials, and the continuous injection of atomized asphalt is not affected by the continuous agitation of the mixed materials in the mixing device 101.

[0052] After the coarse materials are completely dropped into the mixing device 101, the fine materials are sent into the mixing device 101 through the same discharge hole. Since the discharge hole is located at the upper end of the mixing device 101, the fine materials will first mix with the materials in the upper region after entering, and then spread to the middle and lower parts under the continuous rotation of the mixing assembly. Throughout the process, the mixing assembly always remains rotating, not only mechanically mixing the coarse materials, atomized asphalt, and fine materials to generate a certain shear force, promoting the uniform coating of the asphalt film on the aggregate surface, but also avoiding local accumulation of fine materials due to gravity. This synergistic method of multiple materials entering in stages and the continuous work of the mixing assembly can effectively improve the uniformity of material mixing, laying a good foundation for the subsequent incorporation of modifiers.

[0053] Further, when it is necessary to introduce nano calcium carbonate modifier into the mixing device 101, the feed inlet 104 is first closed. The sealing can be achieved by a gate valve or a butterfly valve provided at the feed inlet 104 to prevent the modifier from overflowing from the feed inlet 104 during the addition process, and to avoid the entry of external air or impurities into the mixing device 101 to affect the mixing environment. At this time, the piston rod 304 stops reciprocating while keeping the discharge hole open, i.e., the position of the piston rod 304 is locked, so that the discharge hole remains unobstructed, and the piston rod 304 no longer vibrates. This not only retains the communication channel between the sleeve 301 and the mixing device 101, but also avoids interference with the materials that have entered the mixing device 101.

[0054] The addition path of the nano-calcium carbonate modifier is coordinated with the conveying path of the coarse and fine materials. Specifically, it is added from the upper inlet of the sleeve 301, and with the help of the inclined structure of the sleeve 301 and its own gravity, it slides down along the internal channel of the sleeve 301 and enters the stirring device 101 through the open discharge hole. This design utilizes the existing structure of the sleeve 301 as the conveying channel for the modifier, eliminating the need for an additional dedicated feed pipe, simplifying the equipment structure and reducing the risk of material residue.

[0055] During this process, the mixing assembly within the mixing device 101 maintains continuous rotation. This continuous operation ensures that the newly introduced nano-calcium carbonate modifier is quickly incorporated into the mixing material. Through the shearing and tumbling action of its blades, the modifier is evenly dispersed throughout the mixture of coarse materials, fine materials, and atomized asphalt. This prevents the modifier from accumulating at the bottom of the device due to gravity settling, ensuring sufficient contact between the modifier and all components of the mixture, thereby maximizing its enhancing effect on the mechanical properties and durability of the asphalt mixture. Throughout the process, the rotation parameters of the mixing assembly can be maintained or adjusted according to actual mixing requirements to adapt to changes in material viscosity during the modifier addition stage.

[0056] Furthermore, the mixing assembly, as the core structure for achieving uniform mixing of materials within the mixing device 101, mainly consists of a tilting shaft 110 and several mixing blade assemblies. The tilting shaft 110 is cylindrical, with its axis coinciding with the central axis of the mixing device 101. Its two ends are rotatably connected to the top cover 106 and the bottom shaft frame 105 of the mixing device 101 via bearings, and can be driven by a motor to achieve 360° rotation. The several mixing blade assemblies are fixedly connected to the side wall of the tilting shaft 110, specifically by welding or bolting, to ensure that they do not loosen during high-speed rotation.

[0057] The mixing blade assemblies are distributed at certain intervals along the axial direction of the turning shaft 110, forming a multi-layer structure. Each layer of mixing blade assembly can contain 2 to 4 turning blades, which are evenly distributed along the circumference of the turning shaft 110. Each turning blade adopts a rectangular or arc-shaped plate structure with an edge inclined at a 30° to 45° angle to enhance the pushing and shearing effect on the material.

[0058] Preferably, the multi-layer distribution design enables the stirring blade assembly to form a three-dimensional mixing flow field in the stirring device 101. Specifically, the lower stirring blade assembly stirs the bottom material upwards, the upper assembly pushes the top material downwards, and the middle assembly is responsible for lateral shearing of the material. The three components work together to effectively break the vortex dead angle formed during the stirring process, and are particularly suitable for the initial mixing of atomized asphalt and coarse materials, as well as the dispersion process of nano calcium carbonate modifier. Compared to the traditional single-layer stirring blade that can only achieve local stirring, this multi-layer structure can continuously disturb the material in the axial and radial directions, significantly improving the mixing uniformity.

[0059] Referring to Figures 3-9 As shown, a permeable asphalt mixture device is shown for implementing the above-mentioned permeable asphalt mixture preparation method. Specifically, the permeable asphalt mixture device includes a stirring device 101 and a piston mechanism connected to the upper end of the stirring device 101.

[0060] Specifically, the piston mechanism includes a piston rod 304, a driving part, and a material guiding part. The driving part drives the piston rod to move reciprocally in the material guiding part. The piston rod 304, the driving part, and the material guiding part are each provided with two sets, and each set of the piston rod 304, the driving part, and the material guiding part is correspondingly arranged.

[0061] Further, the stirring device 101 is the core area for material mixing, including a heat insulation shell 102, a mixing assembly, and a constant temperature plate 103. The mixing assembly is arranged in the heat insulation shell 102, and the constant temperature plate 103 is installed between the heat insulation shell 102 and the mixing assembly. The constant temperature plate 103 adopts a ring structure and is tightly fitted to the inner side wall of the heat insulation shell 102, forming a surrounding temperature maintaining layer.

[0062] Preferably, the main material of the constant temperature plate 103 is selected from composite silicate insulation materials, and multiple groups of temperature sensors are embedded in the inside. The sensors are arranged at intervals of 120° on the inner side of the constant temperature plate 103, which can monitor the temperature field distribution inside the stirring device 101 in real time.

[0063] When the temperature needs to be reduced to 130°C~140°C, the temperature sensor captures the internal temperature change, and only relies on the heat preservation characteristics of the heat preservation layer to achieve slow cooling, avoiding sudden temperature drop that causes sudden change of material viscosity. This design enables the stirring device 101 to stably maintain the required temperature range at each step, providing a suitable temperature environment for the combination of coarse materials and atomized asphalt, the dispersion of nano calcium carbonate modifier, and reducing the interference of external environmental temperature fluctuations on the mixing process.

[0064] The bottom end of the stirring device 101 is provided with an inlet 104 for the introduction of atomized asphalt and the discharge of the mixed material after completion of the mixing; the inner wall is fixedly connected with a shaft support 105 to provide support for the turnover shaft 110. The top of the stirring device 101 is fixedly installed with a top cover 106, the top cover 106 is integrally provided with two first discharge ports 107, the inner wall of the top cover 106 is fixedly connected with a sliding seal ring 108 to ensure the internal sealing performance.

[0065] The upper surface of the top cover 106 is installed with a turnover motor 109, the output end of the turnover motor 109 is connected with a turnover shaft 110 through a shaft coupling, the surface of the turnover shaft 110 is rotatably connected with the inner wall of the top cover 106 and the inner wall of the shaft support 105 through bearings to ensure stable rotation. The surface of the turnover shaft 110 is fixedly installed with turnover vortex leaves 111, the surface of the turnover vortex leaves 111 is provided with mixing rods 112, one end surface of the turnover vortex leaves 111 is fixedly sleeved with turnover stirring leaves 113, and the spiral directions of the turnover vortex leaves 111 and the turnover stirring leaves 113 are opposite, which together constitute a stirring blade assembly to realize the sufficient turnover and mixing of the material through the reverse spiral movement.

[0066] The material guiding part is connected to the top of the stirring device 101, and each of the two material guiding parts is provided with a second discharge port 201. Each first discharge port 107 is connected with a second discharge port 201 to form a channel, and each material guiding part comprises a support outer cylinder 202, the second discharge port 201 is opened on the support outer cylinder 202, one end of each support outer cylinder 202 is fixedly connected with a protective shell 203 to form protection for the internal components, the other ends of the two support outer cylinders 202 are respectively connected with a combined hopper 207, the combined hopper 207 has two distribution ports 206, each distribution port 206 is fixedly connected with a support ring 204 through a plurality of connecting columns 205, and the inner side of the support outer cylinder 202 is fixedly connected with the outer side of the support ring 204.

[0067] Further, the combined hopper 207 also has an inlet port, the inlet port is in communication with the interiors of the two distribution ports 206, the material is sent from the inlet port to the two distribution ports 206, the top of the combined hopper 207 is connected with an adjusting bin 208, and the adjusting bin 208 is connected with a plurality of feeding hoppers 209.

[0068] The driving part is arranged in the interior of the material guiding part and comprises a sleeve 301, the sleeve 301 is arranged in the support ring 204, the sleeve 301 is connected with the distribution port 206 and is arranged in an inclined manner, the sleeve 301 is fixedly provided with a protruding butt joint rotary head 302 at both ends, one butt joint rotary head 302 is connected with the distribution port 206, thereby realizing the communication between the combined hopper 207 and the interior space of the sleeve 301 and realizing the stable conveying of the material.

[0069] The piston rod 304 is operable to move in the sleeve 301, the sleeve 301 is in the support outer cylinder 202, the piston rod 304 extends to one side of the support outer cylinder 202 to form an extension cylinder 305, the extension cylinder 305 can be regarded as a part of the piston rod 304 rod body, a hexagonal sliding groove 306 is formed on the extension cylinder 305, an elastic material blocking film 307 is connected to one side of the piston rod 304, a buffer ring 308 is arranged on the other side of the piston rod 304, the buffer ring 308 is connected with one end of the sleeve 301, and the elastic material blocking film 307 and the buffer ring 308 are used for buffering the impact force, and sealing and buffering effects are achieved.

[0070] The other side of the piston rod 304 is fixedly connected with a guide sliding column 309, the guide sliding hole 303 is arranged on the butt joint rotating head 302, the guide sliding column 309 is slidably inserted into the guide sliding hole 303, and the stable sliding of the piston rod 304 is guaranteed.

[0071] The protective shell 203 is provided with a material blocking plate 401, the material blocking plate 401 is hollow and provided with a reinforcing ring 402 inside, the inner wall of the reinforcing ring 402 is fixedly connected with a sealing ring 403, the surface of the sealing ring 403 is in sliding connection with the surface of the extension cylinder 305, and the sealing effect is enhanced. One side of the material blocking plate 401 is provided with a mounting plate 405, the mounting plate 405 is fixedly connected with a guide sliding rod 404, a hole is formed in the material blocking plate 401 and is inserted with the guide sliding rod 404, and the guide sliding rod 404 plays a positioning and guiding role.

[0072] The mounting plate 405 is fixedly provided with a premixing motor 406 on one side, the output end of the premixing motor 406 is fixedly sleeved with a hexagonal sliding block 407, the surface of the hexagonal sliding block 407 is connected with the inner wall of the hexagonal sliding groove 306, when the premixing motor 406 is started, the output end is telescopic, and then the piston rod 304 is driven to realize reciprocating movement, preferably, the premixing motor 406 can be a linear motor.

[0073] The extension cylinder 305 is further provided with a push-pull guide frame 408, the push-pull guide frame 408 is provided with a threaded cylinder 409 and a sliding cylinder 410, the inner wall of the sliding cylinder 410 is in sliding connection with the surface of the guide sliding rod 404.

[0074] Further, one side of the mounting plate 405 is provided with a blanking motor 411, an output end of the blanking motor 411 is connected with a threaded push rod 412, the blocking plate 401 and the mounting plate 405 are both provided with holes, the threaded push rod 412 penetrates the holes on the blocking plate 401 and the mounting plate 405, the threaded push rod 412 is screwed with the threaded cylinder 409, when the blanking motor 411 is started, the output end drives the threaded push rod 412 to rotate, and then drives the push-pull guide frame 408 to move, the push-pull guide frame 408 is fixedly connected with the extension cylinder 305, and thus drives the piston rod 304 to reciprocate. The blanking motor 411 and the premixing motor 406 are respectively used to generate a pushing force through screw rotation and directly generate a pushing force, and are doubly used on the piston rod 304, so as to ensure the power of the piston rod 304.

[0075] The embodiments of the specific implementation are the preferred embodiments of the application, and do not limit the protection scope of the application, so that: any equivalent changes made according to the structure, shape, principle of the application should be covered within the protection scope of the application.

Claims

1. A method for preparing permeable asphalt mixture, characterized in that, The methods include, Step S1: Select coarse material with a particle size that meets the design requirements, put it into the heating device, heat the coarse material to 170℃~190℃, and subject it to high-frequency vibration. Under the action of periodic mechanical force, the coarse material overcomes the van der Waals force and friction between particles, breaks the naturally existing agglomeration state, and forms a preliminary dispersed loose structure. Step S2: Stir the coarse material and cool it to 150℃~160℃. At the same time, heat the molten asphalt to 160~180℃, atomize it into 5~10μm droplets, spray it in, and stir. Step S3: Add fine materials and stir to ensure that the asphalt, fine materials and coarse materials are in full contact under shear force; Step S4: Continue stirring and lower the temperature of the mixed part to 130℃~140℃, then introduce 5%~8% of nano-calcium carbonate modifier; Step S5: Increase the stirring speed to 80r / min~120r / min to uniformly disperse the nano-calcium carbonate in the asphalt film and form a stable composite system with the asphalt; The coarse material is composed of one or two types of basalt aggregate and granite aggregate.

2. The method for preparing permeable asphalt mixture according to claim 1, characterized in that, In step S1, the high-frequency vibration is achieved by an inclined piston mechanism. The piston mechanism includes a piston rod (304) and a sleeve (301). The sleeve (301) is inclined to the horizontal plane and is hollow. The upper end of the sleeve is the coarse material inlet end. A material drop hole is opened on the side wall of the sleeve (301). The piston rod (304) blocks the lower end of the sleeve (301). The piston rod (304) reciprocates along the axial direction of the sleeve (301) to open or close the material drop hole. The high-frequency vibration is generated by the periodic reciprocating motion of the piston rod (304).

3. The method for preparing permeable asphalt mixture according to claim 2, characterized in that, The periodic reciprocating motion of the piston rod (304) creates a temporary void structure between the coarse material particles.

4. The method for preparing permeable asphalt mixture according to claim 2, characterized in that, During the reciprocating motion of the piston rod (304), when the piston rod (304) moves upward along the axial direction of the sleeve (301), the rod body of the piston rod (304) blocks the material drop hole, and the top end of the piston rod (304) rigidly collides with the coarse material in the sleeve (301) to generate a first vibration wave. At the same time, positive pressure is formed in the sleeve (301) due to the upward movement of the piston rod (304). When the piston rod (304) moves downward along the sleeve (301) axially, the rod body of the piston rod (304) moves away from the discharge hole, and the top of the piston rod (304) impacts the bottom of the sleeve (301) to generate a second vibration wave. At the same time, a negative pressure is formed inside the sleeve (301) due to the downward movement of the piston rod (304). The first vibration wave and the second vibration wave are superimposed in the sleeve (301), and together with the airflow impact generated by the positive and negative pressure difference, the coarse material produces a spiral rolling displacement under the combined action of vibration force, gravity component force and air pressure thrust.

5. The method for preparing permeable asphalt mixture according to claim 4, characterized in that, The opening time of the discharge hole is 1.5 to 2 times the closing time; the single stroke of the piston rod (304) is 15 mm to 25 mm.

6. The method for preparing permeable asphalt mixture according to claim 2, characterized in that, In steps S2 and S3, the cooling process of the coarse material and the introduction of the atomized asphalt and the fine material are both completed in the mixing device (101). The upper end of the mixing device (101) is connected to the discharge hole, and the lower end of the mixing device (101) is provided with a feed inlet (104). The atomized asphalt is sprayed from the feed inlet (104) into the mixing device (101) in a direction opposite to the direction of the coarse material. The fine material is sent into the mixing device (101) from the discharge hole after the coarse material is discharged.

7. The method for preparing permeable asphalt mixture according to claim 6, characterized in that, The mixing device (101) is equipped with a mixing component. During the reciprocating motion of the piston rod (304), the coarse material falls into the mixing device (101) through the discharge hole. The atomized asphalt is sprayed into the mixing device (101) through the feed inlet (104). The fine material falls into the mixing device (101) through the discharge hole. During this process, the mixing component rotates continuously to mix the materials in the mixing device (101).

8. The method for preparing permeable asphalt mixture according to claim 7, characterized in that, In step S4, when the nano-calcium carbonate modifier is introduced, the feed port (104) is closed, the piston rod (304) stops moving while the discharge hole is open, the nano-calcium carbonate modifier enters the stirring device (101) from the sleeve (301), and the mixing component continues to rotate.

9. The method for preparing permeable asphalt mixture according to claim 7, characterized in that, The mixing assembly includes a turning shaft (110) and several stirring blade assemblies. The stirring blade assemblies are all connected to the side wall of the turning shaft (110) and are distributed at intervals along the axial direction of the turning shaft (110) to form multiple layers.

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