A method for constructing dry-hard concrete for airport pavements

Abstract

This invention provides a method for constructing dry-hard concrete pavements for airports, relating to the field of road construction technology. The method includes the following steps: Step 1: Preparing dry-hard concrete; Step 2: Surveying and setting out; Step 3: Installing formwork; Step 4: Mixing dry-hard concrete; Step 5: Spreading the dry-hard concrete within the formwork at the construction site; Step 6: Vibrating the spread dry-hard concrete; Step 7: Leveling, compacting, and smoothing the vibrated dry-hard concrete; Step 8: Roughening the surface of the dry-hard concrete; Step 9: Covering and curing the roughened dry-hard concrete until the curing period is complete, then removing the formwork, thus completing the airport pavement construction. In this invention, dry-hard concrete is used for pavement construction. The low fluidity of dry-hard concrete accelerates the concrete forming speed, shortens the formwork removal time, reduces the construction period, improves construction efficiency, and saves construction costs.

Description

Technical Field

[0001] This invention relates to the field of road construction technology, and in particular to a method for constructing dry-hard concrete for airport pavements. Background Technology

[0002] Airport pavement construction projects play a crucial role in social development, and the construction of concrete pavements is complex. Specifically, airport pavement construction refers to airport pavements with a cement concrete surface layer, often called rigid pavements. Due to their good load-bearing capacity, strong resistance to corrosion from water, aviation fuel, and de-icing agents, and long service life, they are widely used in current airport pavement design and construction.

[0003] Application CN114575213B, authorized by the patent application, relates to the field of concrete and specifically discloses a concrete pouring construction method for road construction, including the following steps: (1) excavating the foundation trench; (2) laying the foundation; (3) installing the steel reinforcement frame; (4) forming the mold cavity; (5) pouring high-toughness concrete; (6) pouring high-strength concrete; (7) dismantling the steel mold; and (8) road surface maintenance. This application has the effect of reducing the need for frequent maintenance of municipal roads and lowering maintenance costs.

[0004] However, in the above construction methods, traditional concrete is used during pouring. Traditional concrete has high fluidity and slow molding speed, resulting in a long construction period. Summary of the Invention

[0005] This invention provides a method for constructing dry-hard concrete for airport pavements, which solves the technical problem that traditional concrete construction methods are slow to form and result in long construction periods.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for constructing dry-hard concrete for airport pavements includes the following steps:

[0008] Step 1: Prepare dry-hardened concrete;

[0009] Step 2: Surveying and setting out, measuring the construction site environment, and making templates;

[0010] Step 3: Install the template;

[0011] Step 4: Mix the dry-hardened concrete and transport the mixed dry-hardened concrete to the construction site;

[0012] Step 5: Spread the dry-hardened concrete within the formwork at the construction site;

[0013] Step 6: Vibrate the spread, dry-hardened concrete.

[0014] Step 7: Level, compact, and grout the dry-hardened concrete after vibration;

[0015] Step 8: Roughen the surface of the dry, hard concrete;

[0016] Step 9: Cover and cure the roughened dry concrete until the curing period is over, then remove the formwork. The airport pavement construction is now complete.

[0017] Preferably, in step 1, the formulation of the dry-hard concrete includes the following elements:

[0018] Cement, fine aggregate, and coarse aggregate;

[0019] The cement may be selected from any one of silicate cement, ordinary silicate cement or road silicate cement as cement material, and the strength grade of the selected cement shall not be lower than 42.5.

[0020] The fine aggregate should be natural sand, and its fineness modulus should be between 2.6 and 3.2. For natural sand used in the same mix proportion, the variation range of its fineness modulus should not exceed 0.3.

[0021] The coarse aggregate can be crushed stone or broken pebbles, and two single-size coarse aggregates should be mixed in proportion to meet the minimum loose porosity requirements.

[0022] Preferably, in step 3, the template is a custom steel template.

[0023] Preferably, in step 4, the dry-hard concrete is mixed at a mixing plant. The mixing time is controlled at 90 seconds from the completion of feeding to the start of mixing after discharge. The slump of the dry-hard concrete should be less than 20 mm. When the consistency is controlled by a Vebe consistency meter, it should be greater than 15 seconds. After mixing, the mixed dry-hard concrete is transported to the construction site by a transport vehicle.

[0024] Preferably, in step 6, a self-propelled high-frequency vibrator is used to vibrate the dry-hard concrete, and the self-propelled high-frequency vibrator travels at a speed of 0.7-0.8 m / min.

[0025] Preferably, in step 9, after the strength meets the design requirements, the formwork is removed, and the curing time is no less than 14 days.

[0026] Preferably, in step 4, a dry-hard concrete mixing device is used to mix the dry-hard concrete. The dry-hard concrete mixing device is mounted on a gantry frame, which is used to move across the construction surface. The dry-hard concrete mixing device includes a base, the lower part of which is mounted on the surface of the gantry frame. A tank and a blade assembly are respectively provided at both ends of the base surface. The tank and the blade assembly are spaced apart. A servo slide rail is provided between the blade assembly and the base. The servo slide rail is used to drive the blade assembly to move closer to or away from the tank. A discharge port is provided at the end of the tank near the blade assembly. The blade assembly cooperates with the servo slide rail and rotates within the tank.

[0027] The upper part of the tank is equipped with a coarse aggregate adding device, which is used to intermittently supply coarse aggregate to the tank.

[0028] Preferably, an engine unit is provided at the end of the tank away from the blade assembly, and the output end of the engine unit is connected to the rotating shaft of the tank by a belt. The rotating shaft is located on the side of the tank away from the blade assembly, and the engine unit is used to drive the tank to rotate.

[0029] The impeller assembly includes a stirring assembly and an intermittent opening and closing assembly. The stirring assembly includes a drive shaft connected to the engine belt. A first gear is provided at the output end of the drive shaft. The first gear meshes with a second gear. The second gear is connected to a third gear via a transmission rod. The second gear and the third gear are respectively located at both ends of the transmission rod. The third gear meshes with a fourth gear. The fourth gear and the first gear are located at opposite ends of the same horizontal line segment. A stirring shaft is provided on the side of the fourth gear away from the first gear. The stirring shaft cooperates with the servo slide rail for rotation within the tank. Several stirring rods are provided on the circumferential outer wall of the stirring shaft.

[0030] Preferably, the intermittent opening and closing device includes a turntable disposed between the first gear and the fourth gear. The turntable is located on one side of the transmission shaft, and one side of the turntable is connected to the first gear via a drive rod. A boss is provided on the side of the turntable near the fourth gear, and the boss is located on the edge of the turntable surface. The side of the boss near the fourth gear is used to engage a push rod, which is located in the middle of the swing rod. The upper part of the swing rod is hinged to the surface of a mounting block, which is located on the upper part of the blade assembly. The bottom end of the swing rod is attached to a push rod, which is located on the side of the swing rod near the fourth gear. The push rod is hinged to the bottom end of the swing rod. Next, the end of the push rod away from the swing rod is slidably disposed in the through hole, the through hole is disposed through the shaft of the fourth gear, one end of the through hole is used to house the push rod, and the other end of the through hole is used to slidably house the stirring shaft, a slider is disposed on the outer wall of the end of the stirring shaft near the fourth gear, the slider is slidably disposed in the limiting groove, the limiting groove is disposed on the inner wall of the through hole along the length direction of the through hole, the fourth gear cooperates with the limiting groove to drive the stirring shaft to rotate, a return spring is disposed on the end of the stirring shaft away from the fourth gear, and an opening and closing assembly is disposed between the stirring shaft and the inner wall of the tank, the opening and closing assembly is used to intermittently open and close the tank inlet.

[0031] Preferably, the tank inlet is located on the outer wall of the tank on the side away from the paddle assembly, a cover plate is slidably disposed inside the inlet, a mating block is disposed on the side of the cover plate near the paddle assembly, the mating block is used to cooperate with the opening and closing assembly, and a tension spring is disposed at the end of the cover plate away from the mating block, the tension spring is disposed between one end of the cover plate and the inner wall of the inlet;

[0032] The opening and closing assembly includes a hinge rod, with both ends of the hinge rod connected to the inner wall of the tank. A mating rod is hinged to the middle of the hinge rod, with one end of the mating rod connected to the end of the stirring rod near the return spring, and the other end of the stirring rod abutting against the mating block near the tension spring.

[0033] The stirring rod has a sliding hole at one end near the return spring, and the mating rod is movably disposed within the sliding hole.

[0034] Preferably, both ends of the gantry are set on the surface of the servo rails, and the two servo rails are set on both sides of the construction surface. The coarse aggregate adding device includes a feeding box and a storage box. The feeding box is set on one end surface of the gantry, and the storage box is set on the upper part of the tank. A screw feeder is set between the feeding box and the storage box, and the lower part of the storage box is set against the feed inlet of the tank.

[0035] Preferably, the surface of the gantry frame is provided with a plurality of discharge pipes at intervals, the input end of the discharge pipe is connected to the discharge port of the tank, the output end is set towards the ground, and each discharge pipe is arranged along the length of the gantry frame;

[0036] The gantry frame ground is also provided with several vibration components at intervals. Each vibration component includes a drive motor, and the output shaft of the drive motor is connected to each vibration component by a belt. Each vibration component includes a pulley, one end of which is connected to a fifth gear. The fifth gear is rotatably mounted on the surface of the gantry frame. The pulley is connected to the drive motor belt. Several sixth gears are provided between the bottom surface of the fifth gear and the gantry frame. The sixth gears are spaced apart on the outer wall of the fifth gear and mesh with the outer wall of the fifth gear. A Z-shaped rod is provided on the side of the sixth gear near the gantry frame. One end of the Z-shaped rod is connected to the center of the sixth gear, and the other end is connected to a vibrating rod. The end of the Z-shaped rod near the sixth gear passes through the gantry frame.

[0037] Compared with the prior art, the beneficial effects of the present invention are:

[0038] This invention provides a method for constructing dry-hard concrete pavements for airports, relating to the field of road construction technology. The method includes the following steps: Step 1: preparing dry-hard concrete; Step 2: surveying and setting out; Step 3: installing formwork; Step 4: mixing dry-hard concrete; Step 5: spreading the dry-hard concrete within the formwork at the construction site; Step 6: vibrating the spread dry-hard concrete; Step 7: leveling, compacting, and smoothing the vibrated dry-hard concrete; Step 8: roughening the surface of the dry-hard concrete; Step 9: covering and curing the roughened dry-hard concrete until the curing period is complete, then removing the formwork, thus completing the airport pavement construction. In this invention, dry-hard concrete is used for pavement construction. Dry-hard concrete has low fluidity, which accelerates concrete forming speed, shortens demolding time, shortens the construction period, improves construction efficiency, saves construction costs, and enhances the pavement's inherent properties, increasing its strength and extending its service life. Attached Figure Description

[0039] Figure 1 This is a flowchart of a method for constructing dry-hard concrete for airport pavement according to the present invention.

[0040] Figure 2 This is a schematic diagram of the gantry structure of the present invention;

[0041] Figure 3 This is a schematic diagram of the dry-hard concrete mixing device of the present invention.

[0042] Figure 4 This is a schematic diagram of the intermittent opening and closing component structure of the present invention;

[0043] Figure 5 This is a schematic diagram of the fourth gear structure of the present invention;

[0044] Figure 6 This is a schematic diagram of the cover plate installation according to the present invention;

[0045] Figure 7 This is a schematic diagram of the installation of the vibratory tamping assembly of the present invention;

[0046] Figure 8 This is a schematic diagram of the vibratory tamping assembly structure of the present invention.

[0047] In the diagram: 1. Gantry frame; 2. Base; 3. Tank body; 4. Paddle assembly; 5. Servo slide rail; 6. Engine assembly; 7. Drive shaft; 8. First gear; 9. Second gear; 10. Transmission rod; 11. Third gear; 12. Fourth gear; 13. Stirring shaft; 14. Stirring rod; 15. Turntable; 16. Drive rod; 17. Boss; 18. Push rod; 19. Swing rod; 20. Push rod; 21. Perforation; 2 2. Slider; 23. Limiting groove; 24. Return spring; 25. Cover plate; 26. Mating block; 27. Tension spring; 28. Hinge rod; 29. ​​Mating rod; 30. Sliding hole; 31. Servo track; 32. Feeding box; 33. Storage box; 34. Screw feeder; 35. Discharge pipe; 36. Drive motor; 37. Pulley; 38. Fifth gear; 39. Sixth gear; 40. Z-shaped rod; 41. Vibrating rod. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In the description of this invention, it should be noted that the terms "upper," "lower," "inner," "outer," "front end," "rear end," "both ends," "one end," and "the other end," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention. Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0050] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installed," "equipped with," "connected," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be a connection within two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0051] Example 1

[0052] Please see Figure 1-8 A method for constructing dry-hard concrete pavement for airport runways includes the following steps:

[0053] Step 1: Prepare dry-hardened concrete;

[0054] Step 2: Surveying and setting out, measuring the construction site environment, and making templates;

[0055] Step 3: Install the template;

[0056] Step 4: Mix the dry-hardened concrete and transport the mixed dry-hardened concrete to the construction site;

[0057] Step 5: Spread the dry-hardened concrete within the formwork at the construction site;

[0058] Step 6: Vibrate the spread, dry-hardened concrete.

[0059] Step 7: Level, compact, and grout the dry-hardened concrete after vibration;

[0060] Step 8: Roughen the surface of the dry, hard concrete;

[0061] Step 9: Cover and cure the roughened dry concrete until the curing period is over, then remove the formwork. The airport pavement construction is now complete.

[0062] In step 1, the formulation of dry-hard concrete includes the following elements:

[0063] Cement, fine aggregate, and coarse aggregate;

[0064] The cement may be selected from any one of silicate cement, ordinary silicate cement or road silicate cement as cement material, and the strength grade of the selected cement shall not be lower than 42.5.

[0065] The fine aggregate should be natural sand, and its fineness modulus should be between 2.6 and 3.2. For natural sand used in the same mix proportion, the variation range of its fineness modulus should not exceed 0.3.

[0066] The coarse aggregate can be crushed stone or broken pebbles, and two single-size coarse aggregates should be mixed in proportion to meet the minimum loose porosity requirements.

[0067] In step 3, a custom-made steel template is used.

[0068] In step 4, the dry-hard concrete is mixed at the mixing plant. The mixing time is controlled at 90 seconds from the completion of feeding to the start of mixing after discharge. The slump of the dry-hard concrete should be less than 20 mm. When the consistency is controlled by a Vebe consistency meter, it should be greater than 15 seconds. After the mixing is completed, the mixed dry-hard concrete is transported to the construction site by a transport vehicle.

[0069] In step 6, a self-propelled high-frequency vibrator is used to vibrate the dry-hard concrete. The self-propelled high-frequency vibrator travels at a speed of 0.7-0.8 m / min.

[0070] In step 9, after the strength meets the design requirements, the formwork is removed, and the curing time is no less than 14 days.

[0071] The working principle and beneficial effects of the above embodiments are as follows:

[0072] Before construction, dry-hard concrete mix materials should be prepared, and appropriate raw materials should be selected for concrete mix design. In this scheme, dry-hard concrete is composed of cement, fine aggregate, and coarse aggregate. The pavement concrete should use cement with low shrinkage, high wear resistance, good frost resistance, and low alkali content. Rotary kiln-produced silicate cement, ordinary silicate cement, or road silicate cement are preferred. The cement strength grade should not be lower than 42.5, and fast-hardening, early-strength cement should not be used. The fine aggregate should be durable, clean, and hard in texture. Natural sand is preferred, with a fineness modulus of [missing value]. The fineness modulus of sand used in the same mix proportion should not vary by more than 0.3; crushed stone or broken pebbles are preferred as coarse aggregate. The coarse aggregate is hard, durable, wear-resistant and clean. The synthetic gradation of crushed stone or broken pebbles is made by mixing two single-size coarse aggregates. The proportion of each size is determined based on the minimum loose porosity. After the raw materials are selected, the mix proportion of concrete is prepared according to the design strength.

[0073] After the raw materials are selected, the site is surveyed and laid out. The construction site environment is measured, and the plane position and elevation should meet the design and specification requirements. The template is made according to the measurement results.

[0074] After the templates are made, they are installed. Custom steel templates are preferred because they are structurally stable and the installation is more secure. Templates can be customized according to the size of the pavement panels, forming them in one go and making construction more convenient. Wooden templates can be used instead of steel templates in irregular locations. The plane position and top elevation of the templates must meet the design requirements. The templates must be firmly fixed and their straightness and verticality should be checked. The joints of the templates and the contact points between the templates and the base layer are all sealed with asphalt felt. The geotextile is laid flat.

[0075] During template fabrication and installation, the selected raw materials can be mixed at a mixing plant to improve construction efficiency. The mixing plant strictly adheres to the construction mix proportions, with the mixing time controlled at 90 seconds from the completion of material feeding to the start of mixing at discharge. The concrete slump should be less than 20mm, and when using a Vebe consistency meter to control consistency, it should be greater than 15 seconds. After the testing engineer verifies that the mixed material meets the requirements, it is discharged. Transportation can be carried out using 15m... 3 Dump trucks transport freshly mixed dry hard concrete to the construction site. The transport roads are planned in advance and hardened to ensure that the dump truck tires are free of mud.

[0076] Next, the paving operation is carried out. The mixed dry hard concrete is unloaded in front of the row-type high-frequency vibrator. A small excavator is used for initial placement of the material. After the row-type high-frequency vibrator is vibrated, the missing material in some areas is manually supplemented by shovels. During the vibration of the wooden rammer, the material is manually supplemented again in some areas until the appropriate elevation is reached.

[0077] After the concrete placement is completed, uniform vibration is performed on the dry-hardened concrete. A self-propelled high-frequency vibrator is used, with the walking speed controlled at 0.7-0.8 m / min to ensure thorough vibration. After vibration, the side tie rods are manually driven to the designed depth using a small hammer. The end dowel bars, reinforced areas, and light pit areas are vibrated using a handheld immersion vibrator, overlapping the vibrator area by at least 50 cm. The immersion vibrator power should be no less than 1.1 kW, and the vibration frequency no less than 50 Hz. The concrete vibration time can be determined based on the power and frequency of the high-frequency vibrator and the workability of the mixture, ideally until the concrete stops settling, no more air bubbles escape, and a slurry-like surface appears. Over-vibration should be avoided. The concrete filling pouring time is calculated from the latest time of the concrete surface layer on both sides. When laying the filling concrete, protective measures should be taken for the edges and surfaces of the already poured concrete surfaces on both sides to prevent edge damage and slurry adhesion. For the already poured surface layers on both sides, the cracks on the sides of the dummy joints should be covered with a full-thickness isolation material with a width of not less than 300mm. A 2cm thick rubber material should be used as a walking pad for equipment. When finishing the surface, a neat straight line should be drawn at the junction of the new and old concrete with a trowel, and the mortar on the edge of the slab should be cleaned thoroughly.

[0078] After vibration, the dry-hardened concrete is leveled, compacted, and the mortar is raised. Before leveling, a wooden tamper is used to vibrate back and forth 3-4 times to ensure that the aggregate distribution on the concrete surface is uniform, dense, and the surface mortar is even. Then, a roller is used 2-3 times to ensure that the mortar on the concrete surface is full and of uniform thickness to meet the finishing requirements. After the initial leveling, the surface of the dry-hardened concrete is smoothed twice with a wooden trowel, and then smoothed twice with a steel trowel to ensure that the surface is flat, dense, without exposed sand, and free from sand holes, trowel marks, air bubbles, cracks, etc.

[0079] Then, roughening is performed. The timing of roughening depends on factors such as temperature, wind force, and the slump of the mixture. It's crucial to control the timing; roughening too early or too late is not advisable. During roughening, there should be a certain thickness (3-4mm) of mortar in front of the brush, but it shouldn't accumulate. The ideal consistency is when pressing a finger into the concrete surface leaves an indentation, but the mortar doesn't stick. The roughening brush is made of a 2.5mm diameter rubber rod. During the roughening process, to ensure straightness, a straightedge is placed perpendicular to the longitudinal joint of the slab, and the brush is evenly pulled along the straightedge. To avoid wrinkles, the roughening process should not be stopped or vibrated midway. Each brush stroke should be moistened with clean water, and any cement slurry adhering to the brush should be cleaned frequently to ensure smooth and regular groove edges.

[0080] Finally, the roughened, dry-hardened concrete is covered for curing. When the concrete surface no longer sticks to the geotextile and light pressure with a finger leaves no obvious marks, promptly cover it with non-woven geotextile for curing to prevent excessive water loss. After the concrete has fully set and the surface begins to turn white, promptly sprinkle water to keep the concrete surface moist. Curing should not be done too early, as this can easily dilute the surface cement, reduce the water-cement ratio and strength of the surface mortar, and cause localized sanding and roughening later. The curing time should be determined based on the concrete strength gain, preferably not less than the time it takes for the cement concrete to reach 90% of its design strength, and should be no less than 14 days. During the curing period, protect the finished product by setting up warning flags, closing traffic, and preventing damage to the pavement by people, livestock, and various vehicles until the curing period is over and the concrete strength meets the design requirements. Once the pavement concrete strength meets the design requirements, remove the formwork, and the airport pavement construction is complete.

[0081] In this invention, dry-hard concrete is used for pavement construction. Dry-hard concrete has low fluidity, making it easier to form, accelerating the concrete forming speed, shortening demolding time, reducing the construction period, improving construction efficiency, and saving construction costs. Furthermore, dry-hard concrete enhances its own properties, increases pavement strength, and extends service life. Steel formwork is used, making the formwork installation more secure. Customized formwork can be made according to the size of the pavement panels, allowing for one-time forming and making construction more convenient. During vibration, a row-type high-frequency vibrator is used, ensuring more thorough vibration of the dry-hard concrete, improving its bonding properties, and greatly reducing concrete defects. The leveling process is more comprehensive, ensuring a smooth, dense, and sand-free surface, free from sand holes, trowel marks, air bubbles, cracks, and other defects, thus improving construction quality.

[0082] Example 2

[0083] Please see Figure 1-8 In step 4, a dry-hard concrete mixing device is used to mix dry-hard concrete. The dry-hard concrete mixing device is mounted on a gantry frame 1, which is used to move on the construction surface. The dry-hard concrete mixing device includes a base 2, the lower part of which is mounted on the surface of the gantry frame 1. A tank body 3 and a blade assembly 4 are respectively provided at both ends of the surface of the base 2. The tank body 3 and the blade assembly 4 are spaced apart. A servo slide rail 5 is provided between the blade assembly 4 and the base 2. The servo slide rail 5 is used to drive the blade assembly 4 to move closer to or away from the tank body 3. A discharge port is provided at the end of the tank body 3 near the blade assembly 4. The blade assembly 4 cooperates with the servo slide rail 5 and rotates inside the tank body 3.

[0084] The upper part of the tank body 3 is provided with a coarse aggregate adding device, which is used to intermittently supply coarse aggregate to the tank body 3.

[0085] An engine set 6 is provided at one end of the tank body 3 away from the blade assembly 4. The output end of the engine set 6 is connected to the rotating shaft of the tank body 3 by a belt. The rotating shaft is located on the side of the tank body 3 away from the blade assembly 4. The engine set 6 is used to drive the tank body 3 to rotate.

[0086] The impeller assembly 4 includes a stirring assembly and an intermittent opening and closing assembly. The stirring assembly includes a drive shaft 7, which is connected to the engine set 6 by a belt. A first gear 8 is provided at the output end of the drive shaft 7. The first gear 8 meshes with a second gear 9. The second gear 9 is connected to a third gear 11 through a transmission rod 10. The second gear 9 and the third gear 11 are respectively located at both ends of the transmission rod 10. The third gear 11 meshes with a fourth gear 12. The fourth gear 12 and the first gear 8 are located at both ends of the same horizontal line segment. A stirring shaft 13 is provided on the side of the fourth gear 12 away from the first gear 8. The stirring shaft 13 cooperates with the servo slide rail 5 to rotate inside the tank 3. Several stirring rods 14 are provided on the circumferential outer wall of the stirring shaft 13.

[0087] The intermittent opening and closing device includes a turntable 15, which is disposed between the first gear 8 and the fourth gear 12. The turntable 15 is located on one side of the transmission shaft, and one side of the turntable 15 is connected to the first gear 8 via a drive rod 16. A boss 17 is provided on the side of the turntable 15 near the fourth gear 12. The boss 17 is located on the edge of the surface of the turntable 15 and is used to cooperate with a push rod 18. The push rod 18 is located in the middle of a swing rod 19. The upper part of the swing rod 19 is hinged to the surface of a mounting block, which is located on the upper part of the blade assembly 4. The bottom end of the swing rod 19 is attached to a push rod 20, which is located on the side of the swing rod 19 near the fourth gear 12 and is hinged to the bottom end of the swing rod 19. The push rod 20 is slidably disposed in the perforation 21 at one end away from the swing rod 19. The perforation 21 passes through the shaft of the fourth gear 12. One end of the perforation 21 is used to house the push rod 20, and the other end of the perforation 21 is used to slidably house the stirring shaft 13. A slider 22 is disposed on the outer wall of the end of the stirring shaft 13 near the fourth gear 12. The slider 22 is slidably disposed in the limiting groove 23. The limiting groove 23 is disposed on the inner wall of the perforation 21 along the length direction of the perforation 21. The fourth gear 12 cooperates with the limiting groove 23 to drive the stirring shaft 13 to rotate. A return spring 24 is disposed at the end of the stirring shaft 13 away from the fourth gear 12. An opening and closing assembly is disposed between the stirring shaft 13 and the inner wall of the tank 3. The opening and closing assembly is used to intermittently open and close the feed port of the tank 3.

[0088] The feed inlet of the tank 3 is located on the outer wall of the tank 3 away from the blade assembly 4. A cover plate 25 is slidably disposed inside the feed inlet. A mating block 26 is disposed on the side of the cover plate 25 near the blade assembly 4. The mating block 26 is used to cooperate with the opening and closing component. A tension spring 27 is disposed at the end of the cover plate 25 away from the mating block 26. The tension spring 27 is disposed between one end of the cover plate 25 and the inner wall of the feed inlet.

[0089] The opening and closing assembly includes a hinge rod 28, with both ends of the hinge rod 28 connected to the inner wall of the tank body 3. A mating rod 29 is hinged to the middle of the hinge rod 28. One end of the mating rod 29 is connected to the end of the stirring rod 14 near the return spring 24, and the other end of the stirring rod 14 abuts against the mating block 26 on the side near the tension spring 27.

[0090] The stirring rod 14 has a sliding hole 30 at one end near the return spring 24, and the mating rod 29 is movably disposed within the sliding hole 30.

[0091] The working principle and beneficial effects of the above embodiments are as follows:

[0092] Dry-hard concrete has a relatively low water-cement ratio, which places high demands on the mixing capacity and uniformity of the mixing equipment, as well as the timeliness of transportation. The lower water-cement ratio means that the concrete contains relatively less water and has a higher viscosity. This requires the mixing equipment to have sufficient mixing power and efficiency to fully disperse the water and mix it evenly with solid particles such as cement. The mixing equipment needs to ensure that water and cement particles are fully mixed to ensure the homogeneity of the concrete. In addition, due to its relatively low water-cement ratio, dry-hard concrete is more prone to caking during transportation than conventional cement. Therefore, a secondary mixing equipment is needed to pre-mix the dry-hard concrete before laying and vibrating it, thereby improving the yield of the finished dry-hard concrete product.

[0093] First, dry-hard concrete is mixed at the batching plant. Precast concrete is then loaded into tank 3 via transport trucks. The precast concrete undergoes secondary mixing in tank 3. During loading, the precast concrete is loaded from the side of tank 3 closest to the paddle assembly 4. After loading, coarse aggregate is added to the coarse aggregate adding device. During the secondary mixing process, coarse aggregate is gradually added to further reduce the water-cement ratio and meet the paving requirements. This avoids the problem of adding too much coarse aggregate during the premixing of dry-hard concrete at the batching plant, which would result in an excessively low water-cement ratio, increasing transportation difficulties. It also avoids the need for the batching plant to mix for a long time to fully integrate the coarse aggregate with the cement and fine aggregate. By adding a portion of the coarse aggregate first and then adding the remaining amount through secondary mixing, the required water-cement ratio for paving can be achieved. This reduces the requirements for the batching plant's mixing equipment, shortens the premixing time, and improves the batching plant's discharge efficiency.

[0094] When mixing is performed using a dry-hard concrete mixing device, the precast concrete filling tank 3 is completed. The servo slide rail 5 is then activated, bringing the paddle assembly 4 closer to the tank 3 and finally fully inserting the paddle assembly 4 into the tank 3. The fourth gear 12 is mounted on the base 2 via bearings, ensuring that the mixing shaft 13 is always located inside the tank 3. When the servo slide rail 5 is working, it is only necessary to bring the fourth gear 12 closer to the mixing shaft 13 to drive the mixing shaft 13. One end of the tank 3 near the paddle assembly 4 is open, and a baffle is provided at the open end to form a mixing zone inside the tank 3, preventing cement from being exposed inside the tank 3. A discharge port can be provided at the bottom of the baffle, and a filling port can be provided at the top. Precast concrete is filled through the filling port and discharged through the discharge port during laying. Thus, the split design of the tank 3 and the paddle assembly 4 expands the filling operation space, improves filling efficiency, and also facilitates subsequent maintenance of the tank 3.

[0095] During stirring, the first gear 8 drives the second gear 9 to rotate, the second gear 9 drives the third gear 11 to rotate through the transmission rod 10, the third gear 11 rotates and drives the fourth gear 12 to rotate, and the fourth gear 12 rotates through the limiting groove 23 to drive the slider 22 and the stirring shaft 13 to rotate, so that the stirring rod 14 rotates and stirs the material in the tank 3, achieving the purpose of secondary stirring;

[0096] When the first gear 8 rotates, it drives the turntable 15 to rotate via the drive rod 16. The rotation of the turntable 15 causes the boss 17 to rotate around its center. When the boss 17 rotates to the push rod 18, it pushes the push rod 18 to move away from the boss 17. The push rod 18 then drives the swing rod 19 to swing around the mounting block. When the lower part of the swing rod 19 moves, it pushes the push rod 20 towards the fourth gear 12, thereby pushing the stirring shaft 13 to move within the perforation 21. This causes the stirring shaft 13 to drive the stirring rod 14 to move towards the tank 3. Simultaneously, the stirring shaft 13 continues to rotate, stirring the material on one side of the stirring shaft 13. When the boss 17... When the top rod 18 is driven away, the return spring 24 pushes the mixing shaft 13 to return to its original position. This allows the mixing shaft 13 to move back and forth intermittently within the tank 3 during the rotation and mixing process, thereby reducing the blind zone of mixing and making the mixing more thorough. This ensures the mixing quality of dry-hard concrete. Furthermore, the coarse aggregate adding device can intermittently add coarse aggregate. After the previous part of coarse aggregate is fully mixed, new coarse aggregate can be added continuously for mixing. This not only improves the mixing degree of coarse aggregate but also reduces the load on the mixing rod 14 and the engine assembly 6, thereby extending the service life of the mixing rod 14 and the engine assembly 6.

[0097] When the stirring shaft 13 is pushed to one side, the opening and closing assembly operates, the lower part of the mating rod 29 is pushed, and the mating rod 29 swings around the hinge rod 28, causing the upper part of the mating rod 29 to push the mating block 26 and drive the cover plate 25 to slide to one side, thereby achieving the purpose of opening the cover plate 25. At this time, the feed inlet of the tank 3 is located at the upper part of the tank 3 and below the coarse aggregate adding device. After the cover plate 25 is opened, the coarse aggregate in the coarse aggregate adding device enters the tank 3. When the stirring shaft 13 is reset, the cover plate 25 is driven to close the feed inlet by the tension spring 27, and the mating block 26 pushes the mating rod 29 to reset. At this time, the cover plate 25 is closed. When the tank 3 continues to rotate, the material in the tank 3 will not be exposed from the feed inlet, thereby achieving the purpose of automatic opening and closing of the cover plate 25 and automatic feeding.

[0098] Example 3

[0099] Please see Figure 1-8 Both ends of the gantry frame 1 are set on the surface of the servo track 31, and the two servo tracks 31 are set on both sides of the construction surface. The coarse aggregate adding device includes a feeding box 32 and a storage box 33. The feeding box 32 is set on one end surface of the gantry frame 1, and the storage box 33 is set on the upper part of the tank body 3. A screw feeder 34 is set between the feeding box 32 and the storage box 33. The lower part of the storage box 33 is set against the feed inlet of the tank body 3.

[0100] The surface of the gantry frame 1 is provided with a plurality of discharge pipes 35 at intervals. The input end of the discharge pipe 35 is connected to the discharge port of the tank 3, and the output end is set towards the ground. Each discharge pipe 35 is arranged along the length of the gantry frame 1.

[0101] The gantry frame 1 is also provided with several vibration components at intervals on the ground. Each vibration component includes a drive motor 36. The output shaft of the drive motor 36 is connected to each vibration component by a belt. Each vibration component includes a pulley 37. One end of the pulley 37 is connected to a fifth gear 38. The fifth gear 38 is rotatably disposed on the surface of the gantry frame 1. The pulley 37 is connected to the drive motor 36 by a belt. Several sixth gears 39 are disposed between the bottom surface of the fifth gear 38 and the gantry frame 1. The sixth gears 39 are spaced apart on the outer wall of the fifth gear 38 and mesh with the outer wall of the fifth gear 38. A Z-shaped rod 40 is disposed on the side of the sixth gear 39 near the gantry frame 1. One end of the Z-shaped rod 40 is connected to the center of the sixth gear 39, and the other end is connected to a vibrating rod 41. The end of the Z-shaped rod 40 near the sixth gear 39 passes through the gantry frame 1.

[0102] The working principle and beneficial effects of the above embodiments are as follows:

[0103] The equipment in the feeding box 32 used for transporting coarse aggregate is replenished with coarse aggregate. The coarse aggregate in the feeding box 32 is lifted to the top of the storage box by the screw feeder 34 and then falls into the storage box, thus automatically feeding the coarse aggregate.

[0104] After the mixing in tank 3 is completed, the material is continuously discharged through discharge pipe 35. At this time, the vibration assembly is started to vibrate the discharged material.

[0105] During vibration, the vibrator 41 starts, and the drive motor 36 works, driving each pulley 37 to rotate via a belt. When the pulley 37 rotates, it drives the fifth gear 38 to rotate. When the fifth gear 38 rotates, it drives each sixth gear 39 to rotate. The rotation of the sixth gear 39 drives each Z-shaped rod 40 to rotate. The Z-shaped rod 40 achieves the eccentric setting of the vibrator 41, so that the vibrator 41 can rotate continuously during operation. Thus, when a single vibration component works, it drives multiple vibrators 41 to perform circular motion. This allows multiple vibration components to work simultaneously, and the vibrators 41 of each vibration component to perform circular motion simultaneously, resulting in higher vibration efficiency and avoiding the generation of blind spots in vibration.

[0106] By using synchronous vibration, the problem of coarse and fine aggregates collapsing around the vibrator when it vibrates a local area can be avoided. The poor fluidity of dry-hard concrete can be used to shorten the construction period, while efficient vibration can make the concrete distribution more uniform and reduce the problem of cracking caused by the low water-cement ratio of dry-hard concrete.

[0107] Example 4

[0108] Taking actual construction as an example, in the Chengdu Tianfu International Airport Flight Area Runway Project, Section 09, the locations of concrete mixing plants around the airport were investigated before construction. Based on the maximum allowable time from mixing to finishing of dry-hard concrete, it was determined that if dry-hard concrete mixed directly from the mixing plant was used, the concrete mixer trucks would not be able to reach the airport construction section for paving within the maximum allowable time. The following is the maximum allowable time from mixing to finishing:

[0109]

[0110]

[0111] Since the construction period is in October, and the local temperature is between 13℃ and 19℃, the maximum allowable time for mixing and finishing the dough is compressed to within 90 minutes.

[0112] To address the challenges of short mixing and finishing times for dry-hard concrete, particularly the high construction difficulty associated with large-scale airport paving, this invention utilizes a dry-hard concrete mixing device. Concrete is pre-mixed at a batching plant and then transported to the construction section. The dry-hard concrete mixing device further mixes the concrete, continuously adding coarse aggregate to adjust the water-cement ratio and meet the requirements for dry-hard concrete construction. This simultaneous mixing and paving reduces the workload on the batching plant. The device allows for continuous concrete processing during paving, improving on-site construction efficiency and reducing waiting time at the batching plant. This results in a 40%–60% increase in construction efficiency, significantly reducing the number of personnel required. A gantry crane moves the dry-hard concrete mixing device and vibrating components across the construction section, mixing, paving, and vibrating simultaneously. This reduces the labor intensity of manual hand-held vibrators. Multiple vibrating components work concurrently, ensuring more uniform vibration and reducing subsequent curing difficulties and cracking risks.

[0113] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. A method for constructing dry-hard concrete for airport pavements, characterized in that, Includes the following steps: Step 1: Prepare dry-hardened concrete; Step 2: Surveying and setting out, measuring the construction site environment, and making templates; Step 3: Install the template; Step 4: Mix the dry-hardened concrete and transport the mixed dry-hardened concrete to the construction site; Step 5: Spread the dry-hardened concrete within the formwork at the construction site; Step 6: Vibrate the spread, dry-hardened concrete. Step 7: Level, compact, and grout the dry-hardened concrete after vibration; Step 8: Roughen the surface of the dry, hard concrete; Step 9: Cover and cure the roughened dry concrete until the curing period is over, then remove the formwork. The airport pavement construction is now complete. In step 4, the dry-hard concrete is pre-mixed twice before being laid, and coarse aggregate is gradually added during the second mixing process to further reduce the water-cement ratio. In step 4, a dry-hard concrete mixing device is used to mix dry-hard concrete. The dry-hard concrete mixing device is set on a gantry frame (1). The gantry frame (1) is used to move on the construction surface. The dry-hard concrete mixing device includes a base (2). The lower part of the base (2) is installed on the surface of the gantry frame (1). A tank (3) and a blade assembly (4) are respectively set at both ends of the surface of the base (2). The tank (3) and the blade assembly (4) are spaced apart. A servo slide rail (5) is set between the blade assembly (4) and the base (2). The servo slide rail (5) is used to drive the blade assembly (4) to move closer to or away from the tank (3). A discharge port is set at one end of the tank (3) near the blade assembly (4). The blade assembly (4) cooperates with the servo slide rail (5) and rotates inside the tank (3). The upper part of the tank (3) is provided with a coarse aggregate adding device, which is used to intermittently supply coarse aggregate to the tank (3); An engine unit (6) is provided at one end of the tank (3) away from the blade assembly (4). The output end of the engine unit (6) is connected to the shaft of the tank (3) by a belt. The shaft is located on the side of the tank (3) away from the blade assembly (4). The engine unit (6) is used to drive the tank (3) to rotate. The blade assembly (4) includes a stirring assembly and an intermittent opening and closing assembly. The stirring assembly includes a drive shaft (7), which is belt-connected to the engine assembly (6). A first gear (8) is provided at the output end of the drive shaft (7). The first gear (8) meshes with a second gear (9). The second gear (9) is connected to a third gear (11) via a transmission rod (10). The second gear (9) and the third gear (11) are respectively located at both ends of the transmission rod (10). The third gear (11) meshes with a fourth gear (12). The fourth gear (12) and the first gear (8) are located at both ends of the same horizontal line segment. A stirring shaft (13) is provided on the side of the fourth gear (12) away from the first gear (8). The stirring shaft (13) is used in conjunction with the servo slide rail (5) to rotate inside the tank (3). Several stirring rods (14) are provided on the circumferential outer wall of the stirring shaft (13). The intermittent opening and closing assembly includes a turntable (15) disposed between the first gear (8) and the fourth gear (12). The turntable (15) is located on one side of the transmission rod (10). One side of the turntable (15) is connected to the first gear (8) via a drive rod (16). A boss (17) is provided on the side of the turntable (15) near the fourth gear (12). The boss (17) is located on the edge of the surface of the turntable (15). The boss (17) near the fourth gear (12) is used to cooperate with the push rod (18). The push rod (18) is located in the middle of the swing rod (19). The upper part of the swing rod (19) is hinged to the surface of the mounting block. The mounting block is located on the upper part of the blade assembly (4). The bottom end of the swing rod (19) is located on the push rod (20). The push rod (20) is located on the side of the swing rod (19) near the fourth gear (12). The push rod (20) and the bottom of the swing rod (19) are connected. The push rod (20) is hinged at one end, with the end away from the swing rod (19) slidably disposed in the through hole (21). The through hole (21) passes through the shaft of the fourth gear (12). One end of the through hole (21) is used to house the push rod (20), and the other end of the through hole (21) is used to slidably house the stirring shaft (13). A slider (22) is disposed on the outer wall of the end of the stirring shaft (13) near the fourth gear (12). The slider (22) is slidably disposed in a limiting position. Inside the groove (23), the limiting groove (23) is arranged along the length direction of the perforation (21) on the inner wall of the perforation (21). The fourth gear (12) cooperates with the limiting groove (23) to drive the stirring shaft (13) to rotate. A return spring (24) is provided at the end of the stirring shaft (13) away from the fourth gear (12). An opening and closing assembly is provided between the stirring shaft (13) and the inner wall of the tank (3). The opening and closing assembly is used to intermittently open and close the feed port of the tank (3). The feed inlet of the tank (3) is located on the outer wall of the tank (3) away from the blade assembly (4). A cover plate (25) is slidably arranged inside the feed inlet. A mating block (26) is arranged on the side of the cover plate (25) close to the blade assembly (4). The mating block (26) is used to cooperate with the opening and closing component. A tension spring (27) is arranged at the end of the cover plate (25) away from the mating block (26). The tension spring (27) is arranged between one end of the cover plate (25) and the inner wall of the feed inlet. The opening and closing assembly includes a hinge rod (28), with both ends of the hinge rod (28) connected to the inner wall of the tank body (3). A mating rod (29) is hinged in the middle of the hinge rod (28). One end of the mating rod (29) is connected to the end of the stirring rod (14) near the return spring (24), and the other end of the stirring rod (14) abuts against the mating block (26) on the side near the tension spring (27). The stirring rod (14) has a sliding hole (30) at one end near the return spring (24), and the mating rod (29) is movably disposed within the sliding hole (30).

2. The method for constructing dry-hard concrete for airport pavements according to claim 1, characterized in that: In step 1, the formulation of dry-hard concrete includes the following elements: Cement, fine aggregate, and coarse aggregate; The cement may be selected from any one of silicate cement, ordinary silicate cement or road silicate cement, and the strength grade of the selected cement shall not be lower than 42.

5. The fine aggregate should be natural sand, and its fineness modulus should be between 2.6 and 3.

2. For natural sand used in the same mix proportion, the variation range of its fineness modulus should not exceed 0.

3. The coarse aggregate can be crushed stone or broken pebbles, and two single-size coarse aggregates should be mixed in proportion to meet the minimum loose porosity requirements.

3. The method for constructing dry-hard concrete for airport pavements according to claim 1, characterized in that: In step 3, a custom-made steel template is used.

4. The method for constructing dry-hard concrete for airport pavements according to claim 1, characterized in that: In step 4, the dry-hard concrete is mixed at the mixing plant. The mixing time is controlled at 90 seconds from the completion of feeding to the start of mixing after discharge. The slump of the dry-hard concrete should be less than 20 mm. When the consistency is controlled by a Vebe consistency meter, it should be greater than 15 seconds. After the mixing is completed, the mixed dry-hard concrete is transported to the construction site by a transport vehicle.

5. The method for constructing dry-hard concrete for airport pavements according to claim 1, characterized in that: In step 6, a self-propelled high-frequency vibrator is used to vibrate the dry-hard concrete. The self-propelled high-frequency vibrator travels at a speed of 0.7-0.8 m / min.

6. The method for constructing dry-hard concrete for airport pavements according to claim 1, characterized in that: In step 9, after the concrete strength reaches the design requirements, the formwork is removed, and the curing time is no less than 14 days.

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