A ceramsite sound-absorbing metal sound barrier unit

Abstract

The present invention provides a ceramsite sound-absorbing metal sound barrier unit, comprising a cavity formed by a metal shell, a cement-based sound-absorbing board arranged in the cavity, and starting from the side of the metal shell facing the sound source, the cavity sequentially comprises: a first air layer, a first cement-based sound-absorbing board, a second cement-based sound-absorbing board, and a second air layer. The present invention achieves a comprehensive improvement in the acoustic performance of rail transit sound barrier products.

Description

Technical Field

[0001] The present invention belongs to the technical field of rail transit noise control, and specifically relates to a rail transit metal sound barrier made of cement-based sound-absorbing material with good durability and excellent environmental protection performance, and in particular relates to a sound barrier board composed of a metal shell, a cement-based sound-absorbing board and a cavity. Background Art

[0002] The main noise reduction measures adopted by railways and urban rail transit are to set up sound barriers beside the tracks. After long-term research, the applicant has developed ceramsite sound-absorbing panels that can replace rock wool, polyester fiber and other materials in existing metal shells. The panels are made of ceramsite with different particle sizes as aggregates, cementitious materials, admixtures, etc. The sound barrier products obtained by using such ceramsite sound-absorbing panels in metal shells are lightweight, weather-resistant and have excellent mechanical properties.

[0003] As the applicant conducts in-depth research, it is found that different ceramsite aggregates and the arrangement of different ceramsite sound-absorbing panels in the metal shell will have different effects on the acoustic effects of the sound barrier products. In terms of acoustic effects, sound absorption and sound insulation are two different acoustic concepts with essential differences. Sound absorption refers to the use of sound-absorbing materials or sound-absorbing structures to absorb and consume incident sound energy, reduce reflected sound, and thus reduce noise in the volume. Sound insulation is the use of sound insulation structures to block sound, reduce the transmission of noise, and separate the noisy environment from the environment that requires quietness. For example, noise reduction boxes, sound insulation rooms, and sound insulation screens are commonly used sound insulation devices to ensure the privacy of the indoor environment and reduce the impact of external sounds. It can also be seen from the above concepts that the goals and focuses of sound absorption and sound insulation treatment are different. The goal of sound absorption treatment is to reduce the repeated reflection of sound in the room, that is, to reduce the reverberation sound in the room, shorten the duration of the reverberation sound, and cooperate with the sound quality design. Sound insulation treatment focuses on isolating the noise from the sound source room to the adjacent room, so that the adjacent room is not disturbed by the noise, that is, reducing the background noise and improving the required clarity. Sound absorption and sound insulation are essentially contradictory. Materials with excellent sound absorption performance may also have poor sound insulation performance. In general acoustic materials, sound absorption and sound insulation performance are mutually opposed, but in the design of rail transit sound barriers, it is hoped that the two can be unified within a certain range of excellence. This is the current difficulty in the design of sound barrier products.

[0004] In addition, in the metal sound barrier of rail transit, due to the limitation of metal shell space and the requirement of overall lightweight, the ceramsite sound absorbing board cannot have a large thickness (generally less than 80mm). The thin wall requirement of this ceramsite sound absorbing board makes it particularly difficult to improve its sound insulation performance index. Every increase of 1 decibel in weighted sound insulation requires great technical efforts. In the acoustic component products of railway sound barriers, it is hoped that the (weighted) sound insulation can reach more than 30dB. Summary of the invention

[0005] In order to solve the above-mentioned problems of the prior art, the present invention provides a ceramsite sound-absorbing metal sound barrier unit, which has a certain sound absorption effect and sound insulation performance, and realizes the comprehensive improvement of the acoustic performance of rail transit sound barrier products.

[0006] The present invention provides the following technical solutions:

[0007] A ceramsite sound-absorbing metal sound barrier unit comprises a cavity formed by a metal shell, a cement-based sound-absorbing board is arranged in the cavity, and starting from the side of the metal shell facing the sound source, the cavity comprises in sequence: a first air layer, a first cement-based sound-absorbing board, a second cement-based sound-absorbing board, and a second air layer.

[0008] In which, the metal shell can be an aluminum alloy shell, including a U-shaped main body, a top profile and a bottom profile. The top of the U-shaped main body is provided with inwardly bent transverse bending parts on both sides of the top, and the top profile includes a transverse web, which can cover the inwardly bent transverse bending parts on both sides of the top of the U-shaped main body. Flanges are vertically provided on both sides of the transverse web of the top profile, which can be matched and engaged with the two sides of the transverse bending parts of the U-shaped main body. A number of lower side ribs are provided below the transverse web of the top profile, which can enter the cavity through the gap between the transverse bending parts of the U-shaped main body and are used to fix the cement-based sound-absorbing board. The top profile can be fixed to the U-shaped main body by rivets arranged on the transverse web and the transverse bending parts; the bottom profile is fixed to the inner bottom surface of the U-shaped main body, and is provided with upper side ribs corresponding to the lower side ribs.

[0009] Furthermore, the first cement-based sound absorbing board and the second cement-based sound absorbing board are clamped in parallel between the lower rib and the upper rib, and form air layers on both sides of the cavity of the U-shaped body; an opening is set on the side of the U-shaped body facing the sound source, and the opening rate is 25%-80%, preferably set to 25%-30%; shock-absorbing pads are also set on the connection contact parts between the cement-based sound absorbing board and the metal shell, and on the connection contact parts between the U-shaped body and the top profile.

[0010] Among them, in the cavity, the thickness ratio of each layer satisfies the first air layer: the first cement-based sound-absorbing board: the second cement-based sound-absorbing board: the second air layer = (5-38): (35-50): (5-25): (39-72), and the total thickness of the cement-based sound-absorbing board is ≤60mm.

[0011] Wherein, the thickness of a single-layer cement-based sound-absorbing board is ≥10 mm, preferably ≥15 mm; the total thickness of the cement-based sound-absorbing board is ≥35 mm, preferably ≥40 mm.

[0012] The thickness ratio of the two layers of cement-based sound-absorbing panels satisfies the first cement-based sound-absorbing panel: the second cement-based sound-absorbing panel ≥ 1.2.

[0013] The thickness of the second air layer is greater than the thickness of the first cement-based sound-absorbing board, and preferably greater than the total thickness of the cement-based sound-absorbing board.

[0014] The cement-based sound-absorbing board is made of light aggregate and / or light aggregate ash, cementitious materials, admixtures and water; the light aggregate is ceramsite with a particle size of 1 mm to 3 mm, and the light aggregate ash is ceramsite ash; the cementitious materials include one or more main materials selected from silicate cement, aluminate cement, sulphoaluminate cement, lime, gypsum and water glass, and one or more admixtures selected from fly ash, slag powder, silica fume and volcanic ash; the admixtures include hydrophobic agents, water reducers, thickeners, air entraining agents and nanomaterials; in the cement-based sound-absorbing board, the light aggregate and / or light aggregate ash account for more than 50% of the total mass, preferably more than 70%, and more preferably more than 80%.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are: through the comprehensive adjustment of the number of layers, thickness and air layer of the sound-absorbing board, the metal sound barrier can achieve the optimal sound absorption and sound insulation performance in a limited space, and the basic performance indicators can reach compressive strength ≥ 2MPa, flexural strength ≥ 0.7MPa, surface density not more than 65kg, sound absorption coefficient ≥ 0.77, and weighted sound insulation ≥ 33dB; the further optimized performance indicators reach compressive strength ≥ 2.5MPa, flexural strength ≥ 0.8MPa, surface density not more than 65kg, sound absorption coefficient ≥ 0.8, and weighted sound insulation ≥ 33dB. On the premise of achieving the same sound absorption and insulation effect, the weight of the light aggregate concrete sound barrier used in the past is reduced by more than 20%. The light aggregate of the present invention uses ceramsite with a particle size of 1mm-3mm, and does not use a particle size of more than 3mm. On the one hand, it can increase the proportion of aggregates, and on the other hand, it is conducive to the vibration of ceramsite, and is more conducive to the absorption of sound waves, so as to achieve the overall thickness reduction. The cement-based sound-absorbing board is designed with two layers. Sound waves are incident into the first cement-based sound-absorbing board through the perforated panel, causing the air between the ceramsite particles to vibrate and the sound energy is lost. A part of the sound waves is incident into the second cement-based sound-absorbing board through the first cement-based sound-absorbing board, which better absorbs and blocks the sound and further reduces the propagation of noise. After that, the sound waves pass through the double-layer sound-absorbing board into the second air layer, so that the sound is further absorbed and blocked. In this process, the sound waves are repeatedly reflected and consumed between the double-layer cement-based sound-absorbing board and the air layer. Therefore, the structure and layout of the present invention solve the contradiction between sound absorption and sound insulation, and achieve the best sound absorption and insulation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 It is a schematic diagram of the overall structure of the ceramsite sound-absorbing metal sound barrier unit of the present invention;

[0017] Figure 2 It is a schematic diagram of the cross-sectional structure of the ceramsite sound-absorbing metal sound barrier unit of the present invention;

[0018] Figure 3 is the sound absorption coefficient curve of the product of Example 1-2;

[0019] Figure 4 is the sound insulation curve of the product of Example 1-2;

[0020] Figure 5 is the sound insulation curve of the product in Example 3;

[0021] Figure 6 The sound absorption curves of single-layer and double-layer cement-based sound-absorbing panels with the same total thickness;

[0022] Figure 7 The sound absorption performance of the same cement-based sound-absorbing board with and without an air layer.

[0023] Figure 8 The sound insulation of single-layer sound-absorbing board and double-layer sound-absorbing board is compared under the same total thickness of cement-based sound-absorbing board;

[0024] Fig. 9 It is the sound insulation curve under different second air layer thickness under the same number and thickness of sound absorbing panels;

[0025] Fig.10 The sound insulation performance of single-layer sound-absorbing panels and double-layer sound-absorbing panels is compared under the same total thickness of cement-based sound-absorbing panels.

[0026] Among them, 01-first air layer; 02-first cement-based sound-absorbing board; 03-second cement-based sound-absorbing board; 04-second air layer; 1-U-shaped main body; 11-bending part; 12-opening; 2-top profile; 21-web; 22-flange; 23-lower side rib; 3-bottom profile; 31-upper side rib; 4-shock-absorbing pad. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other implementation methods obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] The present invention adopts construction waste to prepare cement-based sound-absorbing panels, and the cement-based sound-absorbing panels are made of light aggregate and / or light aggregate ash, cementitious materials, admixtures, water, etc. The light aggregate is ceramsite with a particle size of 1mm-3mm, and the light aggregate ash is ceramsite ash. Other materials can be selected from existing products. The cementitious materials can include main materials such as silicate cement, aluminate cement, sulphoaluminate cement, lime, gypsum, water glass, and admixtures such as fly ash, slag powder, silica ash, and volcanic ash; the admixtures can include hydrophobic agents, water reducers, thickeners, air entraining agents, nanomaterials, etc. In the cement-based sound-absorbing panel, light aggregate and / or light aggregate ash account for more than 50% of the total mass, preferably more than 70%, and more preferably more than 80%. A higher proportion of light aggregate and / or light aggregate ash is conducive to increasing the density of ceramsite, improving the refraction and scattering of sound waves in the sound-absorbing panel, and at the same time improving the strength of the panel.

[0029] The cement-based sound-absorbing board of the present invention can be fixed in a cavity formed by a metal shell, and the cavity includes, starting from the side of the metal shell facing the sound source, the following: a first air layer 01, a first cement-based sound-absorbing board 02, a second cement-based sound-absorbing board 03, and a second air layer 04. The double-layer sound-absorbing board can significantly improve the sound absorption coefficient in the low-frequency band, and the air layer can improve the sound insulation of the sound barrier unit and the sound absorption coefficient at certain frequencies. However, due to the construction space beside certain tracks, the space in the cavity of the metal shell is generally limited, about 110-140 mm. Therefore, there is a mutually restrictive relationship between the thickness of the cement-based sound-absorbing board and the thickness of the air layer. By rationally and comprehensively adjusting the thickness of the cement-based sound-absorbing board and the air layer, the overall sound absorption and insulation performance of the sound barrier board can be significantly improved, especially reducing the weight of the sound barrier unit and saving investment.

[0030] Figure 1-2This is an example of a structure of the expanded clay sound-absorbing metal sound barrier unit of the present invention. The metal shell can be an aluminum alloy shell, including a U-shaped main body 1, a top profile 2 and a bottom profile 3. The top of the U-shaped main body 1 is provided with inwardly bent transverse bending parts 11 on both sides of the top, and the top profile 2 includes a transverse web 21. The transverse web 21 can cover the inwardly bent transverse bending parts 11 on both sides of the top of the U-shaped main body 1. Flanges 22 are vertically provided on both sides of the transverse web 21 of the top profile 2, which can match and snap on both sides of the transverse bending part 11 of the U-shaped main body 1. A plurality of lower side ribs 23 are provided below the transverse web 21 of the top profile 2, which can enter the cavity through the gap between the transverse bending parts 11 of the U-shaped main body 1 and are used to fix the cement-based sound-absorbing board. The top profile 2 can be fixed to the U-shaped main body 1 by rivets arranged on the transverse web 21 and the transverse bending part 11; the bottom profile 3 is fixed to the inner bottom surface of the U-shaped main body 1, and is provided with upper side ribs 31 corresponding to the lower side ribs 23. The spacing, number, size, etc. of the lower ribs 23 and the upper ribs 31 can be adjusted during manufacturing according to needs and / or the size of the cement-based sound-absorbing board. The cement-based sound-absorbing board is divided into two layers, which can be clamped in parallel between the lower ribs 23 and the upper ribs 31, and form air layers on both sides of the cavity of the U-shaped body 1. An opening 12 can be set on the side of the U-shaped body 1 facing the sound source, and the opening rate can be 25%-80%. Considering the overall strength of the metal shell and the auxiliary sound absorption effect of the panel, the opening rate can be preferably set to 25%-30%. In order to prevent vibration, stress concentration, and rigid damage to the sound barrier unit during transportation and installation, a shock-absorbing pad 4, such as an EPDM rubber pad, can also be set on the connection contact part between the cement-based sound-absorbing board and the metal shell, and the connection contact part between the U-shaped body 1 and the top profile 2.

[0031] The present invention achieves the coordinated unity of sound absorption and sound insulation effects under the requirement of overall lightweight of the sound barrier unit by studying different arrangements of cement-based sound absorbing panels in the limited cavity space of the metal shell.

[0032] The present invention has found through a large number of experiments that in a limited space, the thickness ratio of each layer satisfies the first air layer: the first cement-based sound-absorbing board: the second cement-based sound-absorbing board: the second air layer = (5-38): (35-50): (5-25): (39-72), and when the total thickness of the cement-based sound-absorbing board is ≤ 60 mm, the sound absorption and sound insulation can be optimized and unified, the sound absorption coefficient can reach more than 0.77, and the weighted sound insulation can reach more than 33 dB. At the same time, the total thickness of the cement-based sound-absorbing board is designed in consideration of the lightweight requirement.

[0033] The cement-based sound-absorbing board is preferably designed as two layers. Under the condition of limited total thickness, three layers or more layers are likely to result in lower strength. The thickness of a single-layer cement-based sound-absorbing board is preferably ≥10mm, more preferably ≥15mm; the total thickness of the cement-based sound-absorbing board is ≥35mm, more preferably ≥40mm. The product of the present invention has a compressive strength of ≥2MPa, a flexural strength of ≥0.7MPa, and a surface density of no more than 65kg, which achieves further lightweight improvement compared to the unoptimized standard (compressive strength of 2MPa under the condition of surface density of 70kg).

[0034] Among them, the first cement-based sound-absorbing board: the second cement-based sound-absorbing board ≥ 1.2, so that the first cement-based sound-absorbing board has a larger thickness. First, it can effectively absorb sound at a larger thickness, and then the thinner second cement-based sound-absorbing board supplements the sound absorption, but the thickness can be thinned to promote the coordinated sound insulation with the air layer. The thickness of the second air layer is preferably greater than the thickness of the first cement-based sound-absorbing board, and more preferably greater than the total thickness of the cement-based sound-absorbing board. The design of the thickness of the second air layer is conducive to effectively dissipating the sound waves passing through the cement-based sound-absorbing board, making up for the insufficient sound insulation capacity of the cement-based sound-absorbing board of corresponding thickness, and improving the sound insulation effect. Under the optimized conditions of the number of layers and thickness, the sound absorption and sound insulation effects of the present invention are further improved, and can reach a sound absorption coefficient of more than 0.8, a weighted sound insulation of more than 33dB, a compressive strength of ≥ 2.5MPa, and a flexural strength of ≥ 0.8MPa.

[0035] Some embodiments and comparative examples of the metal sound barrier unit of the present invention are listed in Table 1. Other preparation conditions of the embodiments and comparative examples are the same.

[0036] Table 1

[0037]

[0038]

[0039] Figure 3-4 Taking Examples 1-2 as examples, the sound absorption coefficient curve and sound insulation curve of the product are shown. It can be seen that the product of the present invention can produce effective sound absorption and sound insulation effects at different frequency ranges. Figure 5 The sound insulation curve of Example 3 is shown separately, which is consistent with the trend of Examples 1-2 and has better sound insulation performance at a higher frequency range. Figure 6 The sound absorption curves of single-layer and double-layer cement-based sound-absorbing panels with the same total thickness are shown. It can be seen that the sound absorption coefficients are not much different in the low frequency range, and the double-layer cement-based sound-absorbing panels have better sound absorption effects in the higher frequency range. Figure 7 The sound absorption performance of the same cement-based sound-absorbing board with an air layer (Example 4) and without an air layer (the thickness of the air layer is 0) is shown. It can be seen that after the air layer is set, the sound absorption coefficient of the sound barrier in the low frequency range can be effectively improved. Figure 8 The figure shows the sound insulation comparison between a single-layer sound-absorbing board and a double-layer sound-absorbing board (without an air layer) under the same total thickness of the cement-based sound-absorbing board (50 mm). It can be seen that the setting of the double-layer sound-absorbing board can effectively improve the sound insulation performance. Fig. 9 The sound insulation curves under different second air layer thicknesses with the same number and thickness of sound-absorbing panels are shown. It can be seen that under the double-layer sound-absorbing panel design, increasing the thickness of the second air layer can effectively improve the sound insulation performance in the mid-frequency range, and the sound insulation performance in the low and high frequency ranges is not much different. Fig.10 The figure shows the sound insulation comparison of single-layer sound-absorbing board and double-layer sound-absorbing board under the same total thickness of cement-based sound-absorbing board (the first air layer is not set, and the thickness of the second air layer is 47.5mm). It can be seen that the setting of the second air layer is relatively better than that of no air layer ( Figure 8 ), the sound insulation performance has been improved, and the difference in sound insulation between the double-layer sound insulation board and the single-layer sound insulation board has been reduced. Figure 3-10 It can be seen that the sound absorption and sound insulation effects are affected by the number of sound-absorbing panels, thickness, and air layer. Especially within the total installation space limit, the adjustment of various factors affects and restricts each other.

[0040] Examples 1-8 in Table 1 show the results of various implementations of the present invention in which the thickness ratio of each layer satisfies the first air layer: the first cement-based sound absorbing board: the second cement-based sound absorbing board: the second air layer = (5-38): (35-50): (5-25): (39-72), and the total thickness of the cement-based sound absorbing board is ≤ 60 mm. It can be seen that in a limited space, the sound absorption coefficient and weighted sound insulation of the metal sound barrier board reach the target optimization index, and the strength performance is also effectively improved.

[0041] Example 6 includes the above-mentioned design conditions of each layer of the present invention, and at the same time, a 10mm cement-based sound-absorbing board (3mm-5mm cementite) is added before the first cement-based sound-absorbing board, and the thickness of the second air layer is appropriately reduced (47.5mm). It can be seen that the sound absorption and sound insulation performance are basically maintained under the conditions of the present invention, but due to the thin thickness of the 10mm cement-based sound-absorbing board, the flexural strength is reduced (0.8MPa). At the same time, due to the slight decrease in the thickness of the second air layer, which is not greater than the total thickness of the sound-absorbing board, the sound insulation performance is also slightly reduced (33dB).

[0042] Example 7 provides an example of adjusting the thickness of two cement-based sound absorbing panels. Although the first cement-based sound absorbing panel is slightly thicker than the second cement-based sound absorbing panel, the difference does not meet the requirement of more than 1.2 times, and the sound absorption coefficient is slightly reduced, failing to reach the optimized index of more than 0.8.

[0043] Example 8 provides a smaller total thickness of two layers of cement-based sound-absorbing panels (35 mm). Due to the insufficient thickness of the panels, although the lightweight index is optimized, the sound absorption coefficient is slightly reduced and does not reach the optimized index of 0.8 or above. At the same time, the flexural strength is also reduced.

[0044] Comparative Example 1 provides two equal air layer thicknesses (41.5 mm), combined with Fig. 9 It can be seen that the thickness of the second air layer is too low to effectively dissipate the sound waves, which affects the sound insulation effect and reduces the sound absorption and insulation performance.

[0045] Comparative Examples 2 and 3 both use a single-layer cement-based sound-absorbing board, and the thickness of the two air layers is different. It can be seen from Comparative Example 2 that when the thickness of the second air layer is optimized, although the sound absorption and insulation performance is improved compared with Comparative Example 3 where the air layer is not optimized, it is still inferior to the performance index of the double-layer cement-based sound-absorbing board, and the sound insulation performance cannot meet the index requirement (32dB).

[0046] Comparative Example 4 provides three layers of cement-based sound-absorbing panels of the same thickness. Although the total thickness has not changed and the sound absorption performance is not much different, due to the large number of layers, the thickness of the first cement-based sound-absorbing panel is reduced, so that the sound insulation performance cannot meet the index requirement (32dB), and the strength index is also significantly reduced.

[0047] In Comparative Example 5, an air layer of 10 mm is added between the two cement-based sound-absorbing panels, and the thickness of the second cement-based sound-absorbing panel is increased. Although the sound absorption coefficient is improved, the sound insulation performance is further reduced, indicating that even if an air layer is added in the middle, the problem of the second cement-based sound-absorbing panel being too thick and the second air layer being insufficient cannot be improved.

[0048] The protection scope of the present invention is not limited thereto, and any person skilled in the art can easily make changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A ceramsite sound-absorbing metal sound barrier unit, comprising a cavity formed by a metal shell, a cement-based sound-absorbing board is arranged in the cavity, and the cavity includes the following in order from the side of the metal shell facing the sound source: A first air layer (01), a first cement-based sound absorbing board (02), a second cement-based sound absorbing board (03), and a second air layer (04); The cement-based sound-absorbing board is composed of light aggregate and / or light aggregate ash, cementitious materials, admixtures, and water; the light aggregate is 1-3 mm ceramsite; the light aggregate ash is ceramsite ash; The light aggregate and / or light aggregate ash accounts for more than 50% of the total mass of the cement-based sound-absorbing board; The thickness ratio of each layer satisfies the first air layer: the first cement-based sound-absorbing board: the second cement-based sound-absorbing board: the second air layer = (5-38): (35-50): (5-25): (39-72); The thickness of the first cement-based sound-absorbing board: the thickness of the second cement-based sound-absorbing board ≥ 1.2; The thickness of the second air layer is greater than the thickness of the first cement-based sound-absorbing board; The total thickness of the cement-based sound-absorbing board is ≤60 mm.

2. The ceramsite sound-absorbing metal sound barrier unit according to claim 1 is characterized in that: The metal shell is an aluminum alloy shell, comprising a U-shaped body (1), a top profile (2) and a bottom profile (3); the top of the U-shaped body (1) is provided with inwardly bent transverse bending portions (11) on both sides of the top; the top profile (2) comprises a transverse web (21), which can cover the inwardly bent transverse bending portions (11) on both sides of the top of the U-shaped body (1); the transverse web (21) of the top profile (2) is provided with flanges (22) vertically on both sides, which can match and engage with the transverse bending portions (11) of the U-shaped body (1). On both sides of the bend (11), a plurality of lower ribs (23) are provided below the transverse web (21) of the top profile (2), which can enter the cavity through the gap between the transverse bends (11) of the U-shaped body (1) and are used to fix the cement-based sound absorbing board. The top profile (2) is fixed to the U-shaped body (1) by rivets provided on the transverse web (21) and the transverse bends (11); and the bottom profile (3) is fixed to the inner bottom surface of the U-shaped body (1), and is provided with upper ribs (31) corresponding to the lower ribs (23).

3. The ceramsite sound-absorbing metal sound barrier unit according to claim 2 is characterized in that: The first cement-based sound absorbing plate (02) and the second cement-based sound absorbing plate (03) are clamped in parallel between the lower rib (23) and the upper rib (31), and form air layers on both sides of the cavity of the U-shaped body (1); an opening (12) is provided on the side of the U-shaped body (1) facing the sound source, and the opening rate is 25%-80%; and a shock-absorbing pad (4) is also provided at the connection contact portion between the cement-based sound absorbing plate and the metal shell, and at the connection contact portion between the U-shaped body (1) and the top profile (2).

4. The ceramsite sound-absorbing metal sound barrier unit according to claim 1 is characterized in that: The thickness of a single-layer cement-based sound-absorbing board is ≥10mm; the total thickness of the cement-based sound-absorbing board is ≥35mm.

5. The ceramsite sound-absorbing metal sound barrier unit according to claim 1 is characterized in that: The thickness of the second air layer is greater than the total thickness of the cement-based sound-absorbing board.

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