A laser ranging type Marshall compaction curve real-time monitoring device

Abstract

The utility model belongs to the field of road engineering, concretely relates to a laser ranging formula Marshall compaction curve real -time monitoring device, and compaction hammer rod can be set up on the vertical rod support and slide up and down, and the hammer driving mechanism is used for driving the up and down movement of compaction hammer rod, and the displacement sensor is located just above compaction hammer rod and is used for measuring the displacement of the top end of vertical rod support, and the counting sensor is set up on vertical rod support and is used for detecting the hammering frequency of compaction hammer rod, and the hammer driving mechanism, displacement sensor and counting sensor are connected with the controller, and the device can monitor and record the height change of Marshall test piece in real time during compaction process, provide data support for compaction characteristic analysis after the test is completed. Meanwhile, the height can be detected in the test process, and the test of unqualified test piece is terminated in advance, and the measurement precision is high. This saves the cumbersome operation steps of measuring the height eligibility of test piece by depending on the vernier caliper previously, and the test piece manufacturing efficiency is improved significantly.

Description

Technical Field

[0001] This utility model belongs to the field of road engineering, specifically relating to a laser ranging type Marshall compaction curve real-time monitoring device. Background Technology

[0002] In asphalt pavement construction, compaction quality is a core factor determining pavement service life and performance. The Marshall compaction test, a key laboratory method for evaluating the compaction characteristics of asphalt mixtures, has a specimen formation process highly correlated with the actual pavement compaction process. By analyzing the dynamic change in specimen height with the number of compaction passes (i.e., the Marshall compaction curve), the differences in compaction characteristics of the mixture in the early (front compaction) and later (back compaction) stages can be revealed, such as changes in structural strength development and compactability. This information is crucial for optimizing asphalt mixture mix design (including selecting appropriate gradations and determining the optimal asphalt content) and guiding the determination of on-site construction machinery configuration and rolling process parameters. However, the current conventional Marshall compaction test method has the following main limitations:

[0003] 1. Lack of process data:

[0004] Current methods (Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering, JTG E20-2011 T0702) typically only obtain the final volumetric parameters (such as height and density) of the specimens after compaction and cooling, and cannot record the height data of the specimens after each compaction in real time and continuously. Therefore, it is impossible to plot and analyze Marshall compaction curves that reflect the dynamic behavior of mixture compaction, which limits a deeper understanding of the compaction process.

[0005] 2. The assessment of high qualification is delayed and cumbersome:

[0006] Determining whether the height of the molded specimen meets the specifications (e.g., the standard Marshall specimen height requirement is 63.5mm ± 1.3mm) typically requires manual measurement using tools such as vernier calipers after compaction, cooling, and demolding. If the specimen height does not meet the requirements, the entire test is invalid, requiring re-preparation, heating, and compaction, which is not only inefficient but also wastes materials and time. Furthermore, the inability to obtain real-time height information during the test for early warning makes it impossible to adjust test parameters in a timely manner.

[0007] 3. Difficulty in deeply analyzing compaction characteristics:

[0008] The lack of continuous height data during the compaction process makes it impossible to calculate the density change of the specimen for each compaction, and consequently, to establish a relationship curve between the number of compactions and key volumetric indicators (such as degree of compaction and aggregate void ratio). This data deficiency limits in-depth analysis of the compaction characteristics of the mixture, significantly diminishing the application value of the test results.

[0009] Therefore, there is an urgent need for a specialized device capable of real-time, automatic, and high-precision monitoring and recording of specimen height changes after each compaction during the Marshall compaction test. This device should overcome the aforementioned limitations, providing a reliable raw data foundation for obtaining the Marshall compaction curve, thereby supporting a comprehensive and in-depth analysis of the compaction characteristics of the mixture and significantly improving the efficiency and reliability of the test itself. Utility Model Content

[0010] The purpose of this invention is to provide a special device with a simple structure, high measurement accuracy, and the ability to monitor and record the changes in specimen height during Marshall compaction in real time. This effectively solves the problems of traditional methods being unable to obtain continuous height data in real time and the low efficiency and poor accuracy of manual measurement, providing key technical support for in-depth analysis of the compaction characteristics of asphalt mixtures.

[0011] The technical problem to be solved by this utility model is achieved by the following technical solution: a laser ranging type Marshall compaction curve real-time monitoring device, including a support platform, a pole support, a Marshall compaction mold, a compaction hammer rod, a compaction hammer, a hammer driving mechanism, a displacement sensor, a counting sensor and a controller;

[0012] The upright support is vertically mounted on the support platform, and the Marshall compaction mold is placed on the support platform;

[0013] The compaction hammer rod is slidably mounted on the upright support and is located directly above the Marshall compaction mold. The compaction hammer is located at the lower end of the compaction hammer rod.

[0014] The hammer driving mechanism is used to drive the hammer rod to move up and down.

[0015] The displacement sensor is vertically mounted on the pole support and is located directly above the hammer rod. It is used to measure the displacement of the top of the pole support.

[0016] The counting sensor is mounted on the pole support and is used to detect the number of times the hammer is struck by the compaction hammer.

[0017] The hammer driving mechanism, displacement sensor, and counting sensor are connected to the controller;

[0018] The controller is used to measure and display the height of each compaction in real time.

[0019] In a preferred embodiment of this utility model, the support platform includes a base plate, a buffer pad, and a base;

[0020] The lower end of the upright support is detachably mounted on the base plate;

[0021] The base is parallel to the base plate and can be slidably mounted on the upright support.

[0022] The buffer pads are located between the base and the bottom plate. The base is parallel to the bottom plate and spaced apart to make the upright support more stable. The buffer pads play a buffering role, reducing the impact of vibration on the measurement data and making the entire device more stable.

[0023] In a preferred embodiment of this invention, the buffer pad is a wooden block, and shock-absorbing rubber rings are provided between the upright support and the base, and between the upright support and the base plate. Through the above structure, a buffering effect can be achieved, reducing the impact of vibration on the accuracy of measurement data during compaction.

[0024] In a preferred embodiment of this invention, the compaction hammer is detachably mounted on the compaction hammer rod, facilitating hammer replacement to accommodate Marshall compaction molds of different sizes.

[0025] Preferably, this utility model also includes a circular reflective platform disposed at the top of the pole support, and the displacement sensor is a laser rangefinder sensor;

[0026] The circular reflective platform is coaxially arranged with the pole support, and the laser rangefinder's beam coincides with the axis of the pole support to improve the accuracy of distance measurement and reduce errors caused by pole support swaying.

[0027] Preferably, in this invention, the diameter of the circular reflective platform is greater than 50mm, and the top surface of the circular reflective platform is coated with matte white paint. The paint surface is uniform and without gloss to maximize the intensity of the laser reflection signal from the laser rangefinder sensor, ensuring the stability and accuracy of the measurement.

[0028] Preferably, this utility model also includes an anti-sway guide tube horizontally arranged on the upright support, wherein the anti-sway guide tube is detachably arranged on the upright support;

[0029] The compaction hammer rod is slidably installed inside the anti-sway guide tube to reduce the shaking of the compaction hammer rod during the compaction process. The anti-sway guide tube is detachable and easy to replace the Marshall compaction hammer.

[0030] In a preferred embodiment, this invention further includes a lifting beam, which is slidably mounted on the upright support, and the displacement sensor is fixedly mounted on the lifting beam. The height of the displacement sensor can be adjusted vertically using the lifting beam.

[0031] Preferably, in this utility model, the distance between the displacement sensor and the top of the pole support is greater than 500mm;

[0032] Limiters are installed at the top of the pole support and at a distance of 30cm from the top.

[0033] The lifting beam is located between two limiters to constrain the vertical movement range of the lifting beam, protect the displacement sensor, and prevent the top of the pole support from hitting the displacement sensor or the displacement sensor from slipping off the pole support.

[0034] In a preferred embodiment of this invention, the controller includes a height reset button, a start button, a stop button, a height display, a compaction count display, and a data export interface;

[0035] The height reset key is used to set the displacement sensor measurement value to zero when the upright support is at its lowest point and the Marshall compaction mold is empty, so that the height display of the controller is zero.

[0036] The data export interface is used to connect to a computer or storage device to directly export compaction height data.

[0037] Compared with the prior art, the beneficial effects of this utility model are:

[0038] (1) Real-time monitoring and efficiency improvement: This device can monitor and record the height change of the Marshall specimen in real time during the compaction process, providing data support for the compaction characteristic analysis after the test. At the same time, the height can be detected during the test, and the test can be terminated in advance for unqualified specimens, with high measurement accuracy. This eliminates the cumbersome operation steps of relying on vernier calipers to measure the qualification of specimen height, and significantly improves the efficiency of specimen preparation.

[0039] (2) Data In-Depth Analysis and Application Value: The Marshall compaction data recorded by this device can be used to plot the Marshall compaction curve, thereby evaluating the compaction characteristics of the mixture. This method, through the comparison of positive and negative compaction compaction standards and compaction characteristics, can serve as an important means to optimize the mix design of asphalt mixtures. By enhancing the structural strength of the mixture, it helps to improve the rutting resistance of asphalt pavements and avoid the generation of overly dense mixtures, thereby reducing the occurrence of early-stage asphalt pavement distress. Attached Figure Description

[0040] Figure 1 This is a schematic diagram of the structure of the laser ranging type Marshall compaction curve real-time monitoring device described in this embodiment of the utility model;

[0041] In the diagram, 1 is the support platform, 2 is the upright bracket, 3 is the Marshall compaction mold, 4 is the compaction hammer rod, 5 is the compaction hammer, 6 is the hammer driving mechanism, 7 is the displacement sensor, 8 is the counting sensor, and 9 is the controller.

[0042] 101 Base plate, 102 Buffer pad, 103 Base;

[0043] 10 Circular reflective platform, 11 Anti-sway guide tube, 12 Lifting crossbeam, 13 Limiter;

[0044] 91. Height reset button, 92. Start button, 93. Stop button, 94. Height display, 95. Number of impacts display, 96. Data export interface. Detailed Implementation

[0045] The technical solutions in the embodiments of this utility model will now be clearly and completely described in conjunction with the accompanying drawings.

[0046] like Figure 1 As shown, a laser ranging type Marshall compaction curve real-time monitoring device includes a support platform 1, a pole support 2, a Marshall compaction mold 3, a compaction hammer rod 4, a compaction hammer 5, a hammer driving mechanism 6, a displacement sensor 7, a counting sensor 8, and a controller 9.

[0047] The upright support 2 is vertically mounted on the support platform 1, and the Marshall compaction mold 3 is placed on the support platform 1.

[0048] The compaction hammer rod 4 is slidably mounted on the upright support 2 and is located directly above the Marshall compaction mold 3. The compaction hammer 5 is located at the lower end of the compaction hammer rod 4.

[0049] The hammer driving mechanism 6 is used to drive the hammer rod 4 to move up and down. The hammer driving mechanism 6 is fixedly mounted on the support platform 1. The hammer driving mechanism 6 is a linear module, which is vertically mounted on the support platform 1. The upright bracket 2 is detachably mounted on the slider of the linear module (the specific structure of the linear module is existing technology and will not be described in detail here).

[0050] The displacement sensor 7 is vertically mounted on the pole support 2, located directly above the hammer rod 4, and is used to measure the displacement of the top of the pole support 2.

[0051] The counting sensor 8 is mounted on the pole support 2 and is used to detect the number of blows of the hammer rod 4. The counting sensor 8 is also located at the lower end of the pole support 2 and is used to record the number of blows when the hammer rod 4 is at its lowest point. The counting sensor 8 is a laser sensor.

[0052] The hammer driving mechanism 6, displacement sensor 7, and counting sensor 8 are connected to the controller 9.

[0053] The controller 9 is used to measure and display the height of each compaction in real time. The displacement sensor 7, combined with the signal from the counting sensor 8, records the lowest point position of the compaction hammer 5 during the compaction process, establishing a functional relationship between the compaction height and the number of compactions.

[0054] The support platform 1 includes a base plate 101, a buffer pad 102, and a base 103.

[0055] The lower end of the upright support 2 is detachably mounted on the base plate 101.

[0056] The base 103 is parallel to the base plate 101 and is slidably mounted on the upright bracket 2.

[0057] The buffer pad 102 is located between the base 103 and the bottom plate 101.

[0058] The buffer pad 102 is a wooden block, and shock-absorbing rubber rings (not shown in the figure) are provided between the upright support 2 and the base 103, and between the upright support 2 and the base plate 101.

[0059] The compaction hammer 5 is detachably mounted on the compaction hammer rod 4, and the compaction hammer 5 is threadedly connected to the compaction hammer rod 4.

[0060] The laser-ranged Marshall compaction curve real-time monitoring device also includes a circular reflective platform 10 mounted on the top of the pole support 2, and the displacement sensor 7 is a laser rangefinder. The laser rangefinder is a high-precision laser rangefinder, based on the time-of-flight (ToF) principle, with a minimum range of <30cm, an accuracy of not less than 0.02mm, and features a high sampling frequency (≥100Hz) and peak hold function.

[0061] The circular reflective platform 10 is coaxially arranged with the pole support 2, and the laser rangefinder's beam coincides with the axis of the pole support 2.

[0062] The circular reflective platform 10 has a diameter greater than 50 mm, and its top surface is coated with matte white paint. The circular reflective platform 10 is a metal plate, specifically a steel plate.

[0063] The laser ranging type Marshall compaction curve real-time monitoring device also includes an anti-sway conduit 11 horizontally mounted on the pole support 2. The anti-sway conduit 11 is detachably mounted on the pole support 2. The anti-sway conduit 11 is connected to the pole support 2 via a clamp sleeve.

[0064] The compaction hammer rod 4 is slidably installed inside the anti-sway guide tube 11.

[0065] The laser ranging type Marshall compaction curve real-time monitoring device also includes a lifting beam 12, which is slidably mounted on the upright support 2. The displacement sensor 7 is fixedly mounted on the lifting beam 12. The displacement sensor 7 is located at the end of the lifting beam 12, with the laser emission window facing the center of the circular reflection platform. The lifting beam 12 is connected to the upright support 2 via a clamp sleeve.

[0066] The displacement sensor 7 is located at a distance greater than 500mm from the top of the pole support 2.

[0067] Limiters 13 are provided at the top of the pole support 2 and at a distance of 30cm from the top. The limiter 13 is a ring structure that is sleeved on the pole support 2.

[0068] The lifting beam 12 is located between the two limiters 13.

[0069] The controller 9 includes a height reset button 91, a start button 92, a stop button 93, a height display 94, a compaction count display 95, and an export data interface 96.

[0070] The height reset key 91 is used to set the measured value of the displacement sensor 7 to zero when the upright support 2 is at its lowest point and the Marshall compaction mold 3 is empty.

[0071] The controller 9 can record the compaction height after each Marshall compaction and display it on the height display 94 in real time.

[0072] The data export interface 96 is used to connect to a computer or storage device to directly export compaction height data.

[0073] The specific operating steps of this utility model device are as follows:

[0074] (1) Test preparation: Adjust the height of the lifting beam 12 on the upright support 2 so that the distance from the laser rangefinder to the circular reflective platform 10 is greater than 500mm. Adjust the equipment to keep the laser rangefinder, the circular reflective platform and the hammer rod concentric.

[0075] (2) Place the Marshall test mold and base 103 on the Marshall compactor, put down the compaction hammer 5, turn on the controller power switch, and then click the reset button, i.e. the height reset key 91, to reset. At this time, the height value should be displayed as "0".

[0076] (3) Marshall test: The Marshall compaction test is carried out according to the specifications. The height of the Marshall specimen can be displayed in real time during the compaction process. The display value is used to judge whether the specimen height meets the requirements. If it meets the requirements, the test data is retained. After the test is completed, the Marshall compaction curve is exported (specifically, the number of compactions is used as the horizontal axis and the compaction height is used as the vertical axis to export the corresponding compaction curve).

[0077] (4) Measured volume parameters: After compaction, place the Marshall specimen at room temperature until it cools and is demolded. Remove the surface dust from the specimen, measure the height H and diameter D of the Marshall specimen, and calculate the density γf of the Marshall specimen.

[0078] (5) Data processing: The bulk density γvi under each Marshall compaction condition is calculated based on the measured Marshall specimen height. γfi is obtained by correcting each density according to the measured density. The compaction degree K obtained for each compaction is calculated. After removing outliers, a curve showing the relationship between the logarithm of the number of compactions and the compaction degree is established.

[0079] (6) Compaction characteristics analysis:

[0080] Based on the compaction curves of both sides, the structural strength and compactibility of asphalt mixtures are evaluated. Mixtures with weaker strength or easier compaction have a flatter slope and higher compaction degree. To ensure the structural strength and prevent over-compaction of the mixture, the compaction degree should not be less than 93% after a certain number of compaction passes on the front side, and not less than 97% after a certain number of compaction passes on the back side. When designing mix proportions, by comparing and analyzing the compaction curves, and under the premise of meeting the required compaction degree, the preferred gradation or asphalt content with a larger slope is selected. This can improve the road performance of asphalt mixtures and serves as an optimization method for mix proportion design.

Claims

1. A laser-ranged Marshall compaction curve real-time monitoring device, characterized in that: It includes a support platform (1), a pole support (2), a Marshall compaction mold (3), a compaction hammer rod (4), a compaction hammer (5), a hammer driving mechanism (6), a displacement sensor (7), a counting sensor (8), and a controller (9); The pole support (2) is vertically mounted on the support platform (1), and the Marshall compaction mold (3) is placed on the support platform (1); The compaction hammer rod (4) is slidably mounted on the upright support (2) and located directly above the Marshall compaction mold (3). The compaction hammer (5) is mounted at the lower end of the compaction hammer rod (4). The hammer driving mechanism (6) is used to drive the hammer rod (4) to move up and down; The displacement sensor (7) is vertically downward mounted on the pole support (2). The displacement sensor (7) is located directly above the hammer rod (4) and is used to measure the displacement of the top of the pole support (2). The counting sensor (8) is installed on the pole support (2) and is used to detect the number of times the hammer rod (4) is struck. The hammer driving mechanism (6), displacement sensor (7) and counting sensor (8) are connected to the controller (9); The controller (9) is used to measure and display the height of each compaction in real time.

2. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 1, characterized in that: The support platform (1) includes a base plate (101), a buffer pad (102), and a base (103). The lower end of the upright support (2) is detachably mounted on the base plate (101); The base (103) is parallel to the base plate (101) and is slidably mounted on the upright bracket (2); The buffer pad (102) is located between the base (103) and the bottom plate (101).

3. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 2, characterized in that: The buffer pad (102) is a wooden block, and shock-absorbing rubber rings are provided between the upright support (2) and the base (103) and between the upright support (2) and the base plate (101).

4. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 1, characterized in that: The compaction hammer (5) is detachably mounted on the compaction hammer rod (4).

5. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 1, characterized in that: It also includes a circular reflective platform (10) set at the top of the pole support (2), and the displacement sensor (7) is a laser rangefinder; The circular reflective platform (10) is coaxially arranged with the pole support (2), and the beam of the laser rangefinder coincides with the axis of the pole support (2).

6. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 5, characterized in that: The circular reflective platform (10) has a diameter greater than 50 mm, and the top surface of the circular reflective platform (10) is coated with matte white paint.

7. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 1, characterized in that: It also includes an anti-sway conduit (11) that is horizontally mounted on the pole support (2), and the anti-sway conduit (11) is detachably mounted on the pole support (2); The compaction hammer rod (4) is slidably installed inside the anti-sway guide tube (11).

8. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 1, characterized in that: It also includes a lifting beam (12), which is slidably mounted on the upright support (2), and the displacement sensor (7) is fixedly mounted on the lifting beam (12).

9. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 8, characterized in that: The displacement sensor (7) is more than 500mm away from the top of the pole support (2); Limiters (13) are provided at the top of the pole support (2) and at a distance of 30cm from the top. The lifting beam (12) is located between two limiters (13).

10. The laser ranging type Marshall compaction curve real-time monitoring device according to claim 1, characterized in that: The controller (9) includes a height reset button (91), a start button (92), a stop button (93), a height display (94), a compaction count display (95), and an export data interface (96). The height reset key (91) is used to set the measured value of the displacement sensor (7) to zero when the upright support (2) is at its lowest point when the Marshall compaction mold (3) is empty; The data export interface (96) is used to connect to a computer or storage device to directly export compaction height data.

Images