An instrument and method for testing acoustic parameters of porous asphalt mixture under water immersion conditions

Abstract

The present application discloses an instrument and method for testing the acoustic parameters of porous asphalt mixtures under immersion conditions. The device mainly includes a sound insulation cavity, a loudspeaker, an electronic scale, a probe, and a waterproof specimen carrier. The present application can measure the acoustic parameters of porous asphalt mixtures under different immersion saturation conditions, and can be used to evaluate the changes in the acoustic parameters of porous asphalt mixtures under different immersion conditions, and to evaluate the noise reduction performance of porous asphalt pavements under different rainfall conditions.

Description

Technical Field

[0001] The invention relates to an acoustic parameter test instrument and a test method for porous asphalt mixture under water immersion conditions, belonging to the technical field of road engineering. Background Art

[0002] For areas with long-term high temperatures and heavy rainfall, where rainfall is concentrated during the rainy season, long-term use of heavy-loaded porous asphalt pavement in this environment will cause blockage of voids, seriously reducing the asphalt void ratio, thereby leading to a decline in the traffic noise control functionality of the porous asphalt pavement.

[0003] Currently, the determination of the sound absorption coefficient of porous asphalt mixtures relies heavily on standing wave tube measurements and subsequent field testing. While standing wave tube testing can be sufficient for determining the sound absorption coefficient of mixture specimens during their initial service life, the experimental setup is not designed for the characteristics of asphalt mixtures and can be damaged by specimens containing water or large amounts of dust. While field testing can yield good, practical data, the data volume is often too limited to provide relevant data throughout the entire service life.

[0004] Therefore, the present invention focuses on two aspects and optimizes and improves the standing wave tube instrument guided by the needs of this profession. It mainly takes the test of specimens in a water-containing state as the starting point, focuses on the waterproofness of the experimental device and the reliability of the acoustic test results, and proposes corresponding test methods to provide test methods and test devices for the determination of the sound absorption coefficient of porous asphalt mixtures in a submerged state, so as to realize the estimation of the conditions and their impacts that it may encounter in the later stage. Summary of the Invention

[0005] Technical problem to be solved: This application mainly proposes an instrument and test method for acoustic parameters of porous asphalt mixture under immersion conditions, so as to solve the technical problems in the prior art, such as test pieces containing water or a large amount of dust will cause damage to its device, and although field tests can obtain good actual data, the amount of data is too one-sided and cannot provide relevant data support from the entire service life.

[0006] Technical solution: An instrument for testing the acoustic parameters of porous asphalt mixtures under submerged conditions, consisting of five parts, namely a sound insulation cavity, a loudspeaker, an electronic scale, a probe and a waterproof specimen carrier; the bottom of the waterproof specimen carrier is connected to the electronic scale, the bottom of the sound insulation cavity is connected to the top of the waterproof specimen carrier, the loudspeaker is connected to the top of the sound insulation cavity, and the probe is connected to the bottom of the loudspeaker; the waterproof specimen carrier is a sealed waterproof component used to place submerged asphalt mixture samples; the loudspeaker is a sound wave transmitting device, connected to a computer to control the sound wave transmitting frequency; the probe is a sound wave receiving device, connected to a computer to measure the maximum and minimum sound pressure values ​​of the entire sound pressure field in the cavity to calculate the acoustic parameters.

[0007] The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions comprises the following steps:

[0008] Step 1: Prepare a porous asphalt mixture Marshall specimen according to the Technical Specification for Design and Construction of Drained Asphalt Pavement (JTG / T 3350-03—2020);

[0009] Step 2: Measure the Marshall specimen void ratio (T 0708-2011) according to the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011);

[0010] Step 3: Place the Marshall specimen in an oven at 110°C and dry for 2 hours. Remove the specimen and measure its weight when completely dry.

[0011] Step 4: Prepare a set of waterproof specimen carriers, and calculate the weight of water required under different water content conditions based on the specimen porosity and water density, and calculate the immersion rate of the Marshall specimen with the reading of the electronic scale as a reference; the immersion rate calculation formula is: immersion rate = (WW drain ) / W s Where W is the weight of the submerged specimen, W drain is the weight of the dry specimen, W s is the saturated weight of the water-saturated specimen;

[0012] Step 5: After the waterproof specimen carrier, water, and Marshall specimen are all placed, seal the top of the waterproof specimen carrier containing the specimen with a waterproof plastic film and leave it for 2 hours to allow the water in the waterproof specimen carrier to completely soak the Marshall specimen and prevent water evaporation from affecting the test results;

[0013] Step 6: Clear the electronic scale, place the waterproof specimen carrier and the specimen into the sound insulation cavity, turn on the speaker to emit sound waves in the 80Hz-200Hz band, use the probe to record the difference between the incident sound energy and the reflected sound energy, and calculate the material acoustic parameters according to the formula;

[0014] Step 7: With the water immersion rate of the porous asphalt mixture as the horizontal axis and the calculated acoustic parameters as the vertical axis, the acoustic parameter results are connected in sequence with smooth curves to form a relationship diagram between the water immersion rate and the acoustic parameters; calculate the water immersion rate according to the fourth step based on the electronic scale after it is reset to zero, and measure the water absorption coefficient under different water immersion rate conditions.

[0015] As a preferred technical solution of the present invention: the power of the speaker reaches the standard of 120W+120W, and a full-range speaker is used to meet the requirements of a wider frequency.

[0016] As a preferred technical solution of the present invention: the sound insulation cavity is a barrel-shaped structure, using high-density sound insulation steel, with a height of 1.5m, a wall thickness of 130mm, an outer diameter of 380mm, and an inner diameter of 250mm.

[0017] As an optimal technical solution of the present invention: the waterproof test platform is made of stainless steel, and the waterproof test platform consists of an upper ring and a lower disc, and the upper ring and the lower disc are movably connected; the upper ring has a height of 70mm, an inner diameter of 110mm, and an outer diameter of 240mm; the lower disc has a diameter of 380mm and a height of 100mm.

[0018] As a preferred technical solution of the present invention: a specimen loading door is provided at the bottom of the sound insulation cavity, which can be opened and closed for taking out and placing specimens and a waterproof test platform.

[0019] As a preferred technical solution of the present invention: the calculation formula for calculating the weight of water required under different water content conditions in the fourth step is: Where W W is the weight of water, V W is the volume of water.

[0020] As a preferred technical solution of the present invention: the calculation formula for calculating the acoustic parameters of the material in the sixth step is: E is the total sound energy incident on the material (J); E r is the sound energy reflected by the material (J).

[0021] As a preferred technical solution of the present invention: using the reading after the electronic scale is reset to zero, the specimen immersion rate calculated in the fourth step is used as the horizontal coordinate, and the acoustic parameters measured of the asphalt mixture sample in the sixth step are used as the vertical coordinate. The acoustic parameter results are connected in sequence with a smooth curve to form a relationship diagram between the immersion rate of the immersed specimen and the acoustic parameters.

[0022] As a preferred technical solution of the present invention: the acoustic parameter sound absorption coefficient.

[0023] Beneficial effects: The acoustic parameter test instrument and test method for porous asphalt mixture under immersion conditions described in this application adopt the above technical solution and have the following technical effects compared with the existing technology:

[0024] 1. This application utilizes improved standing wave tube experimental technology to measure the sound absorption coefficient of asphalt mixtures and further determine the relationship between the coefficient and the content of different acoustic media in the mixture. This method can predict the change in the sound absorption coefficient of asphalt mixtures when immersed in water, meeting the requirements for asphalt pavement traffic noise control in areas with long-term heavy loads and heavy rain.

[0025] 2. This invention utilizes improved standing wave tube experimental technology to measure the sound absorption coefficient of asphalt mixtures and further determine the relationship between the coefficient and the content of different acoustic media in the mixture. This method can predict the change in the sound absorption coefficient of asphalt mixtures when immersed in water, meeting the requirements for asphalt pavement traffic noise control in areas with long-term heavy loads and heavy rain.

[0026] 3. The soundproof cavity is used to isolate external noise, provide the sound wave emission and reflection field required for the experiment, and accommodate other related instruments. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 This is a schematic diagram of the structure of the instrument for testing acoustic parameters of porous asphalt mixture under immersion conditions described in this application.

[0028] Figure 2 This is a schematic diagram of the structure of the internal components of the instrument for testing acoustic parameters of porous asphalt mixtures under immersion conditions described in this application.

[0029] Figure 3 This is a diagram for determining the relationship between void blockage and water absorption coefficient changes of different particle size drainage asphalt pavements in long-term heavy load and rainy areas for this application.

[0030] Explanation of the accompanying symbols: 1. Sound insulation cavity; 2. Speaker; 3. Electronic scale; 4. Probe; 5. Waterproof specimen carrier. DETAILED DESCRIPTION

[0031] The present invention will be further described below in conjunction with the accompanying drawings and specific embodiments, but the present invention is not limited to the embodiments. It should be understood that the specific embodiments described herein are merely for explanation of the present invention and are not intended to limit the present invention. After reading the present invention, modifications to various equivalent forms of the present invention by those skilled in the art all fall within the scope defined by the appended claims.

[0032] The specific embodiments of the present invention are further described in detail below with reference to the accompanying drawings:

[0033] Example 1

[0034] like Figure 1 and Figure 2As shown in FIG, the acoustic parameter test instrument for porous asphalt mixture under submerged conditions consists of five parts, namely a sound insulation cavity 1, a loudspeaker 2, an electronic scale 3, a probe 4 and a waterproof specimen carrier 5; the bottom surface of the waterproof specimen carrier 5 is connected to the electronic scale 3, the bottom of the sound insulation cavity 1 is connected to the top of the waterproof specimen carrier 5, the loudspeaker 2 is connected to the top of the sound insulation cavity 1, and the probe 4 is connected to the bottom of the loudspeaker 2; the waterproof specimen carrier 5 is a sealed waterproof component for placing submerged asphalt mixture samples; the loudspeaker 2 is a sound wave transmitting device, which is connected to a computer to control the sound wave transmitting frequency; the probe 4 is a sound wave receiving device, which is connected to a computer to measure the maximum and minimum sound pressure values ​​of the entire sound pressure field in the cavity to calculate the acoustic parameters.

[0035] The power of the speaker 2 reaches the standard of 120W+120W, and a full-range speaker is used to meet the requirements of a wider frequency. The sound insulation cavity 1 is a barrel-shaped structure, made of high-density sound insulation steel, with a height of 1.5m, a wall thickness of 130mm, an outer diameter of 380mm, and an inner diameter of 250mm. The waterproof test platform 5 is made of stainless steel. The waterproof test platform 5 consists of an upper ring and a lower disc, and the upper ring and the lower disc are movably connected; the upper ring has a height of 70mm, an inner diameter of 110mm, and an outer diameter of 240mm; the lower disc has a diameter of 380mm and a height of 100mm. A specimen loading door is provided at the bottom of the sound insulation cavity 1, which can be opened and closed for taking out and placing specimens and the waterproof test platform 5.

[0036] Example 2

[0037] The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions and the method for determining the optimal asphalt-stone ratio of the Marshall specimen based on the asphalt mixture residual rate include the following steps:

[0038] Step 1: Prepare a porous asphalt mixture Marshall specimen according to the Technical Specification for Design and Construction of Drained Asphalt Pavement (JTG / T 3350-03—2020);

[0039] Step 2: Measure the Marshall specimen void ratio (T 0708-2011) according to the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG E20-2011);

[0040] Step 3: Place the Marshall specimen in an oven at 110°C and dry for 2 hours. Remove the specimen and measure its weight when completely dry.

[0041] Step 4: Prepare a set of waterproof test piece carriers 5, and calculate the weight of water required under different water content conditions based on the test piece porosity and water density, and calculate the immersion rate of the Marshall test piece with the reading of the electronic scale 3 as a reference; the immersion rate calculation formula is: immersion rate = (WW drain ) / W sWhere W is the weight of the submerged specimen, W drain is the weight of the dry specimen, W s It is the saturated weight of the specimen after immersion in water, i.e. the weight of the specimen saturated with water.

[0042] Step 5: After the waterproof specimen carrier 5, water, and Marshall specimen are all placed, the top of the waterproof specimen carrier 5 containing the specimen is sealed with a waterproof plastic film and left to stand for 2 hours to allow the water in the waterproof specimen carrier 5 to completely soak the Marshall specimen and prevent water evaporation from affecting the test results;

[0043] Step 6: Clear the reading on the electronic scale 3, place the waterproof specimen carrier 5 together with the specimen into the sound insulation cavity 1, turn on the speaker 2 to emit sound waves in the frequency range of 80Hz-200Hz, use the probe 4 to record the difference between the incident sound energy and the reflected sound energy, and calculate the material acoustic parameters according to the formula;

[0044] Step 7: With the water immersion rate of the porous asphalt mixture as the horizontal axis and the calculated acoustic parameters as the vertical axis, the acoustic parameter results are connected in sequence with smooth curves to form a relationship diagram between the water immersion rate and the acoustic parameters; calculate the water immersion rate according to the fourth step based on the electronic scale after it is reset to zero, and measure the water absorption coefficient under different water immersion rate conditions.

[0045] The calculation formula for calculating the weight of water required under different water content conditions in the fourth step is: (ρ w =1g / cm 3 ), where W w is the weight of water, V W is the volume of water.

[0046] The formula for calculating the acoustic parameters of the material in the sixth step is: E is the total sound energy incident on the material (J); E r is the sound energy reflected by the material (J).

[0047] Use the reading after the electronic scale 3 is reset to zero, the specimen immersion rate calculated in the fourth step as the horizontal axis, and the acoustic parameters measured in the asphalt mixture sample in the sixth step as the vertical axis. Connect the acoustic parameter results in sequence with smooth curves to form a relationship diagram between the immersion rate of the immersed specimen and the acoustic parameters.

[0048] The method for determining the sound absorption coefficient of a Marshall specimen using a porous asphalt mixture acoustic testing device under multi-media conditions includes determining the optimal gradation based on the upper and lower limits of the gradation provided in the "Technical Specification for Highway Asphalt Pavement Construction" (JTG F40-2004); forming five porous asphalt Marshall specimens at the optimal gradation. The underwater weight is measured according to the relevant description in the specification:

[0049] Specimen void ratio = (1-specimen bulk relative density / asphalt mixture theoretical maximum density) * 100

[0050] The void ratios of the four Marshall specimens with different void ratios were calculated to be 1%, 3%, 5% and 7%. If the voids were filled with water, the weight of the voids would be used to calculate the theoretical volume of the void-free specimen based on the specimen size, and then the theoretical volume containing water would be calculated based on the percentage, and then W would be calculated based on the water density. t1 、W t2 、W t3 and W t4 .

[0051] Determine its porosity and dry it in an oven at 110°C for 2 hours to obtain the dry weight W. drain . Draw a curve of its water immersion rate and weight based on its water weight and dry weight.

[0052] Water immersion rate = WW drain / W s

[0053] Add the corresponding weight of water to the waterproof test platform 5, and use the reading of the electronic scale 3 at the bottom as the reference. Place the test piece in and wrap it with a waterproof plastic film to ensure the distribution of water in the test piece, and let it stand for 2 hours. Then put it in the test device for testing. This design method is based on a test device for testing the sound absorption coefficient of porous asphalt under multi-media conditions, focusing on water content and sound absorption coefficient, and conducting comparative tests at five different water contents to determine the relationship between void blockage and sound absorption coefficient changes in drainage asphalt pavement in long-term heavy-loaded and rainy areas. The results can be seen as follows. Figure 3 As shown:

[0054] Using the experimental device, we measured the incident sound energy at 10% water immersion to be 20 erg, and the reflected sound energy measured by probe 4 to be 4.8 erg. Using the formula in step 6, we calculated the sound absorption coefficient to be 0.24. Using the same method, we calculated the sound absorption coefficients of the specimens at different water immersion conditions, as summarized in the following table:

[0055] Water immersion rate 0％ 1％ 3％ 5％ 7％ PAC-20 0.31 0.28 0.24 0.22 0.21 pac-13 0.29 0.25 0.22 0.21 0.21 Dense gradation 0.2 0.2 0.19 0.19 0.19

[0056] To ensure that the final asphalt mixture design meets the performance requirements of the current "Technical Specification for Highway Asphalt Pavement Construction" (JTGF40-2004), the final mixture design must be tested according to the asphalt mixture design index requirements specified in the specification. If it does not meet the requirements, the gradation and void ratio design must be redesigned. Repeat the steps in this design method until the design results meet the asphalt mixture design index requirements specified in the specification.

[0057] Before obtaining the void ratio of the asphalt mixture, theoretical calculations are performed based on the relative composite density of the mineral aggregate, the relative density of the warm mix asphalt, and the volume of the warm mix asphalt mixture to obtain the estimated optimal mix ratio and void ratio of the porous asphalt mixture.

[0058] The embodiments of the present invention are described in detail above with reference to the accompanying drawings. However, the present invention is not limited to the above embodiments. Various changes can be made within the scope of knowledge possessed by ordinary technicians in this field without departing from the spirit of the present invention.

Claims

1. A test method for an acoustic parameter test instrument for porous asphalt mixture under immersion conditions, characterized in that: The acoustic parameter test instrument for porous asphalt mixture under immersion conditions is composed of five parts, namely a sound insulation cavity (1), a loudspeaker (2), an electronic scale (3), a probe (4) and a waterproof specimen carrier (5); the bottom surface of the waterproof specimen carrier (5) is connected to the electronic scale (3), the bottom of the sound insulation cavity (1) is connected to the top of the waterproof specimen carrier (5), the loudspeaker (2) is connected to the top of the sound insulation cavity (1), and the probe (4) is connected to the bottom of the loudspeaker (2); the waterproof specimen carrier (5) is a sealed waterproof component for placing the immersed asphalt mixture sample; the loudspeaker (2) is a sound wave transmitting device connected to a computer to control the sound wave transmitting frequency; the probe (4) is a sound wave receiving device connected to a computer to measure the maximum and minimum sound pressure values ​​of the entire sound pressure field in the cavity to calculate the acoustic parameters. The test method includes the following steps: Step 1: Prepare a porous asphalt mixture Marshall specimen according to the Technical Specification for Design and Construction of Drained Asphalt Pavement (JTG / T 3350-03—2020); Step 2: Measure the Marshall specimen void ratio (T 0708-2011) in accordance with the Test Procedure for Asphalt and Asphalt Mixtures for Highway Engineering (JTG E20-2011). Step 3: Place the Marshall specimen in an oven at 110°C and dry for 2 hours. Remove the specimen and measure its weight when completely dry. Step 4: Prepare a set of waterproof specimen carriers (5), and calculate the weight of water required under different water content conditions based on the specimen porosity and water density, and calculate the immersion rate of the Marshall specimen with reference to the reading of the electronic scale (3); the immersion rate calculation formula is: immersion rate = (WW drain ) / W s Where W is the weight of the submerged specimen, W drain is the weight of the dry specimen, W s is the saturated weight of the water-saturated specimen; Step 5: After the waterproof specimen carrier (5), water and Marshall specimen are all placed, a waterproof plastic film is used to seal the top of the waterproof specimen carrier (5) containing the specimen and the seal is left for 2 hours to allow the water in the waterproof specimen carrier (5) to completely soak the Marshall specimen and prevent water evaporation from affecting the experimental results; Step 6: Clear the electronic scale (3), place the waterproof test piece carrier (5) together with the test piece into the sound insulation cavity (1), turn on the speaker (2) to emit sound waves in the frequency range of 80Hz-200Hz, use the probe (4) to record the difference between the incident sound energy and the reflected sound energy, and calculate the material acoustic parameters according to the formula; Step 7: With the water immersion rate of the porous asphalt mixture as the horizontal axis and the calculated acoustic parameters as the vertical axis, the acoustic parameter results are connected in sequence with smooth curves to form a relationship diagram between the water immersion rate and the acoustic parameters; calculate the water immersion rate according to the fourth step based on the electronic scale after it is reset to zero, and measure the water absorption coefficient under different water immersion rate conditions.

2. The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions according to claim 1 is characterized by: The power of the loudspeaker (2) reaches the standard of 120W+120W, and a full-range loudspeaker is used to meet the requirements of a wider frequency.

3. The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions according to claim 1 is characterized by: The sound insulation cavity (1) is a barrel-shaped structure made of high-density sound insulation steel, with a height of 1.5m, a wall thickness of 130mm, an outer diameter of 380mm, and an inner diameter of 250mm.

4. The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions according to claim 1 is characterized by: The waterproof test piece carrier (5) is made of stainless steel and consists of an upper ring and a lower disc, and the upper ring and the lower disc are movably connected; the upper ring has a height of 70 mm, an inner diameter of 110 mm, and an outer diameter of 240 mm; the lower disc has a diameter of 380 mm and a height of 100 mm.

5. The test method of the instrument for testing acoustic parameters of porous asphalt mixture under immersion conditions according to claim 4 is characterized in that: The bottom of the soundproof cavity (1) is provided with a specimen loading door which can be opened and closed for taking out and placing specimens, as well as a waterproof specimen carrier (5).

6. The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions according to claim 1 is characterized by: The calculation formula for calculating the weight of water required under different water content conditions in the fourth step is: ( ), where W W is the weight of water, V W is the volume of water.

7. The test method of the instrument for testing acoustic parameters of porous asphalt mixture under immersion conditions according to claim 1 is characterized by: The formula for calculating the acoustic parameters of the material in the sixth step is: , E is the total sound energy incident on the material (J); E r is the sound energy reflected by the material (J).

8. The test method of the instrument for testing acoustic parameters of porous asphalt mixture under immersion conditions according to claim 1, characterized in that: After the electronic scale (3) is reset to zero, the water immersion rate of the specimen calculated in the fourth step is used as the horizontal axis, and the acoustic parameters measured in the asphalt mixture sample in the sixth step are used as the vertical axis. The acoustic parameter results are connected in sequence with smooth curves to form a relationship diagram between the water immersion rate of the immersed specimen and the acoustic parameters.

9. The test method of the porous asphalt mixture acoustic parameter test instrument under immersion conditions according to any one of claims 1 to 8, characterized in that: The acoustic parameter is the sound absorption coefficient.

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