A foam cement-based sound-absorbing material with adjustable pore structure and its preparation method

Abstract

The present invention discloses a foam cement-based sound-absorbing material with adjustable pore structure and its preparation method, belonging to the technical field of building functional materials. Aiming at the problems of insufficient regulation of the pore structure, limited sound-absorbing performance and high cost of traditional cement-based sound-absorbing materials, the present invention is based on P.O42.5R Portland cement. Through the synergistic effect of a composite foaming agent, a microporous structure regulator and a composite pore-forming agent, combined with the physical-chemical synergistic foaming method and the three-stage gradient temperature-controlled freeze-drying process, precise regulation of pores from nm to mm is realized, forming an interconnected pore network with a high open porosity. The obtained material has a density of 200~1000 kg / m³, a porosity of 60~90%, a pore diameter coverage range of 2 nm~6 mm, an open porosity of 70~85%, a 28-day compressive strength of 1.83~14.56 MPa, an average sound absorption coefficient of 0.12~0.62 in the frequency range of 250~2000 Hz, and a noise reduction coefficient of 0.14~0.64. The present invention has the characteristics of adjustable pore structure, light weight and high strength, broadband sound absorption, low cost and good durability, and is suitable for noise control fields such as building walls and transportation facilities.

Description

Technical Field

[0001] This application relates to the technical field of building functional materials, and particularly relates to a foam cement-based sound-absorbing material with adjustable pore structure and a preparation method thereof. Background Art

[0002] With the rapid development of urbanization, industrialization, and transportation, noise pollution has become one of the major environmental problems faced by human society. According to a report by the World Health Organization, long-term exposure to noise pollution will seriously affect human physical and mental health, and the vibration caused by noise will also accelerate the aging of mechanical equipment and building structures. Therefore, it is urgent to take effective measures to mitigate the harm caused by noise pollution. In view of the propagation characteristics of noise, using sound-absorbing materials for control in the propagation path is the simplest and most efficient.

[0003] According to the noise mechanism, sound-absorbing materials are divided into resonant and porous sound-absorbing materials. Among them, the application of resonant sound-absorbing materials is severely restricted due to their narrow sound-absorbing frequency band, while porous sound-absorbing materials have been widely used in passive noise control due to their advantages in effective absorption in the high-frequency and broadband ranges, convenient material selection, light weight, and relatively lower cost.

[0004] Currently, commonly used porous sound-absorbing materials include mineral materials, synthetic materials, and metal materials, etc. However, due to problems such as poor durability and adaptability, and high cost, the long-term application of the above raw materials in building structures still faces challenges. On the contrary, cement-based materials, as typical structural materials, provide excellent choices in terms of cost-effectiveness, durability, and mechanical properties, making them the most commonly used building materials. Therefore, developing building porous sound-absorbing materials with good sound-absorbing performance is of great significance for reducing noise pollution in the building environment.

[0005] The invention patent (publication number CN115010513A) uses tailings, construction waste, gypsum, fly ash, cement, etc. as the main raw materials, and uses the decomposition of hydrogen peroxide to obtain a large number of circular holes on the surface and inside of the sound-absorbing board, and then uses a foaming agent with a slightly higher decomposition temperature to decompose during autoclave curing to achieve pore formation, and prepares a cement-based porous sound-absorbing material. The open porosity in its examples is greater than 64 - 70%. This technology uses autoclave curing, resulting in high energy consumption costs. In contrast, this technology innovatively combines physical-chemical synergistic foaming method with freeze-drying method and adds a microporous structure regulator, and the open porosity can reach a larger 70 - 85%, the pore structure is more abundant and complex, and the energy consumption is lower.

[0006] The invention patent (publication number CN110255987A) uses the foaming effect of an anionic surfactant, α-olefin sulfonate, on the basis of ordinary cement to leave more pores during natural air drying, obtaining a foam cement-based porous sound-absorbing material. This technology only uses α-olefin sulfonate anionic surfactant as a physical foaming agent. The pore size of the obtained foam cement-based sound-absorbing material is 3 mm to 15 mm, and the porosity is 15% to 30%. However, in this technology, by adjusting the dosages and ratios of the microporous structure regulator, composite foaming agent, and composite pore-forming agent, a foam cement-based sound-absorbing material with a density of 200 to 1000 kg / m 3 can be obtained, with a porosity of 60% to 90%, a pore size coverage range of 2 nm to 6 mm, and an open porosity of 70% to 85%. It can precisely control the pore structure. The material not only has a greater internal tortuosity but also a larger internal porosity, greatly improving the sound-absorbing performance of the material.

[0007] The invention patent (publication number CN115353365A) adopts an alkali activation technology, using waste incineration ash, granulated blast furnace slag, and fly ash as precursors, supplemented with a foaming agent (aluminum powder), to prepare a porous cement sound-absorbing material. The noise reduction coefficient in its examples is 0.05 to 0.25, and the noise reduction ability is poor. However, the foam cement-based sound-absorbing material prepared by this technology has a noise reduction coefficient of 0.12 to 0.64 and has more excellent sound-absorbing performance.

[0008] The invention patent (publication number CN103739306A) discloses a preparation method of oriented porous cement. Using tert-butanol, camphene, camphor, and camphene-naphthalene blend as organic pore-forming agents, the porous material is prepared through four steps: preparation of cement-based slurry, production of frozen green body, production of cement-based porous green body by freeze-drying method, and curing of the green body. The open porosity is about 50 - 80%. The invention patent (publication number CN106892674A) discloses a method for preparing gradient-oriented porous cement based on a two-phase pore-forming agent system freeze-forming technology. By stirring and mixing cement powder with a mixed solution based on a two-phase pore-forming agent system (water and tert-butanol) into a uniform system, gradient-oriented porous cement material is obtained through freeze-forming, freeze-drying, and curing in sequence. In the examples, the open porosity is 40.21 - 62.81%. The invention patent (publication number CN107619226A) discloses a porous cement membrane, its preparation method and use. Using water as the pore-forming agent, a porous cement membrane with an oriented pore structure is prepared through a freeze-forming process, and its porosity is 40 - 70%. Different from these technologies, the present technology uses a mixed solution of ethylene glycol, benzyl alcohol, and cyclohexanol as a composite pore-forming agent. Based on the different freezing points and sublimation characteristics of the three, an innovative freeze-drying process with three-stage temperature control is designed, which can achieve the full crystallization and segmented sublimation removal of water and the composite pore-forming agent, and innovatively combines the physical-chemical foaming method and microporous structure modifier to effectively design the pore structure and sound absorption performance. The porosity is 60 - 90%, and the open porosity can reach a higher 70 - 85%. Moreover, the freeze-sublimation process is more reasonable, ensuring the strength of the material.

[0009] In summary, although the cement-based porous sound-absorbing materials in the prior art have made certain progress in sound absorption performance, there are still problems such as insufficient regulation of pore structure, limited sound absorption performance, and high cost. The present invention takes cement slurry as the main component, innovatively combines the physical-chemical synergistic foaming method with the vacuum freeze-drying method, and precisely regulates the pore structure by adjusting the dosage and composition ratio of the microporous structure modifier, composite foaming agent, and composite pore-forming agent. At the same time, a freeze-drying process with three-stage temperature control is designed, significantly improving the complexity of the material pore structure and the open porosity, thereby effectively improving the sound absorption performance of the material, solving the problems of insufficient regulation of pore structure, limited sound absorption performance, and high cost in the prior art, and providing an efficient and low-cost solution for noise pollution control in the building environment. Summary of the Invention

[0010] Aiming at the problems of traditional building sound-absorbing materials, such as high density, difficult regulation of pore structure, poor sound-absorbing performance, and high cost, an object of the present invention is to provide a foam cement-based sound-absorbing material with adjustable pore structure. This sound-absorbing material has the advantages of low bulk density, adjustable density, pore size coverage range, proportion of different levels of pores, porosity, and open porosity, light weight and high strength, good sound-absorbing performance, low cost, fireproof and non-combustible, and good durability, achieving effective control of noise in the building environment.

[0011] The above object of the present invention is achieved by the following technical solutions:

[0012] A foam cement-based sound-absorbing material with adjustable pore structure, the raw materials of which are calculated by weight and include: 1000 - 1300 parts of P.O42.5R portland cement, 400 - 600 parts of water, 20 - 100 parts of a composite foaming agent prepared mainly from 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, 10 - 35 parts of a microporous structure regulator prepared mainly from sepiolite powder, zeolite powder, and diatomite, 5 - 30 parts of a composite pore-forming agent prepared mainly from ethylene glycol, benzyl alcohol, and cyclohexanol, and 1 - 20 parts of a quick-setting agent. The density of the foam cement-based sound-absorbing material is 200 - 1000 kg / m 3 , the thickness is 20 - 60 mm, the porosity is 60 - 90%, the pore size coverage range is 2 nm - 6 mm, and the open porosity is 70 - 85%.

[0013] In this technical solution, by adjusting the dosage and composition ratio of the composite foaming agent, the material density, total porosity, and the proportion of pores at the μm and mm levels can be regulated. Secondly, for foam cement-based sound-absorbing materials, porosity is the key to sound energy loss. When the density of the material is too small, its porosity is too large, which will lead to a mismatch between the material and air impedance, a significant reduction in the sound waves dissipated inside the foam cement-based sound-absorbing material, and an obvious decrease in the mechanical properties of the material; while when the density is too large, its porosity is too low, resulting in difficulty for sound waves to enter the material. Preferably, the density of the foam cement-based sound-absorbing material is 200 - 1000 kg / m 3 , and the porosity is 60 - 90%.

[0014] In one or more embodiments, the composite foaming agent includes 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide.

[0015] Furthermore, the mass ratio of 30 wt.% hydrogen peroxide solution, potassium lauryl phosphate, calcium stearate, and coconut oil diethanolamide is (22 - 28):(8 - 14):(1 - 6):(1 - 3). In this technical solution, a composite foaming agent with a mass ratio of 30 wt.% hydrogen peroxide, potassium lauryl phosphate, calcium stearate, and coconut oil diethanolamide of (22 - 28):(8 - 14):(1 - 6):(1 - 3) is used. When creating pores through the physical-chemical synergistic foaming method, on the one hand, a large number of closed pores are formed inside the matrix by the physical foaming agent (potassium lauryl phosphate), and on the other hand, the adjacent pores are connected by the continuous gas generation effect of the decomposition of the chemical foaming agent (hydrogen peroxide), thereby forming a large number of connected pores inside the material. In addition, potassium lauryl phosphate foaming mainly contributes to pores in the μm range, while hydrogen peroxide foaming mainly contributes to pores in the mm range, thus forming a complementary effect, making the pore distribution more reasonable, and the proportion of μm and mm-level pores in the material can be regulated by adjusting the ratio of hydrogen peroxide to potassium lauryl phosphate. And adding calcium stearate and coconut oil diethanolamide as foam stabilizers is beneficial for the bubbles to remain in the slurry, making it not easy to break or prolonging the breaking time, resulting in a higher yield of the foam cement-based sound-absorbing material and being easier to reach the set density.

[0016] In this technical solution, for the foam cement-based sound-absorbing material, different thicknesses will exhibit different sound-absorbing characteristics. Generally speaking, materials with a moderate thickness have good sound-absorbing performance in the medium and high frequency bands, while thicker materials perform better in the low frequency band. However, when the material thickness is too large, its low frequency sound-absorbing performance may decline because the too thick material may cause sound waves to reflect and interfere inside the material, thus affecting the sound-absorbing effect. At the same time, the too thick material may cause problems such as excessive space occupation and difficult construction. Therefore, preferably, the thickness of the foam cement-based sound-absorbing material prepared in this technical solution is 20 - 60 mm.

[0017] In this technical solution, by adjusting the dosage and composition ratio of the microporous structure regulator, the proportion of nm-level micropores in the foam cement-based sound-absorbing material can be regulated, and a larger porosity and a more complex pore structure can be obtained under the condition of higher strength, thereby improving the sound-absorbing performance of the material.

[0018] In one or more embodiments, the microporous structure regulator includes sepiolite powder, zeolite powder, and diatomaceous earth.

[0019] Furthermore, the mass ratio of the sepiolite powder, zeolite powder and diatomaceous earth is (7~12):(1~5):(2~3). In this technical solution, a microporous structure regulator with a mass ratio of sepiolite powder, zeolite powder and diatomaceous earth of (7~12):(1~5):(2~3) is adopted. Among them, sepiolite powder has a special interlayer structure, zeolite powder has a unique spatial network structure, and diatomaceous earth has a fine and porous microstructure. Although their internal structures are different, they are all rich in nm-level micropores, have a large specific surface area, good water absorption, and also have a certain pozzolanic activity. Adding an appropriate amount of microporous structure regulator to the foam cement-based sound-absorbing material can create pores through the sublimation of the water absorbed by the microporous structure regulator during the freeze-drying process, and can also react with cement using the pozzolanic activity of the microporous structure regulator to increase the strength and durability of the material. Furthermore, under the synergistic effect of sepiolite powder, zeolite powder and diatomaceous earth, it can ensure that the foam cement-based sound-absorbing material has sufficient mechanical properties and can regulate the proportion of nm-level pores, further increasing the porosity and pore complexity of the material.

[0020] In addition, if the porosity, pore morphology and thickness of two foam cement-based sound-absorbing material samples are the same, then the smaller the pore diameter of the sample, the more pores there will be inside and the more complex the overall network structure of the pores will be. The number of reflections and refractions generated when sound waves pass through the pores will increase greatly, the contact area between the air inside the material and its adjacent pore walls will increase, and the energy loss caused by the friction and heat transfer generated by the relative movement will also increase. The sound energy absorbed by the material sample will increase, thus improving the sound-absorbing performance. On the contrary, if the pore diameter is too small, it will be difficult for sound waves to enter the interior of the material and direct reflection will occur on its surface, and the sound-absorbing performance will drop greatly at this time. Therefore, the pore diameter of the foam cement-based sound-absorbing material should not be too large or too small, and there will be an optimal pore diameter range to make its sound-absorbing performance the best. Preferably, the pore diameter coverage range of the foam cement-based sound-absorbing material prepared by this technical solution is 2nm~6mm.

[0021] In this technical solution, by adjusting the dosage and composition ratio of the composite pore-forming agent, foam cement-based sound-absorbing materials with different open porosity can be obtained under the same density and pore diameter coverage range. Generally speaking, the sound-absorbing performance of materials with high open porosity is better than that of materials with low open porosity, but this is not completely certain. The size of the open porosity not only determines the complexity of the internal pore structure, but also directly affects the flow resistivity of the material, thus changing the sound-absorbing performance of the material. Preferably, the open porosity of the foam cement-based sound-absorbing material prepared by this technical solution is preferably 70~85%.

[0022] In one or more embodiments, the composite pore-forming agent includes ethylene glycol, benzyl alcohol and cyclohexanol.

[0023] Further, the mass ratio of ethylene glycol, benzyl alcohol, and cyclohexanol is (6 - 8):(1 - 2):(1 - 2). In this technical solution, using a composite pore-forming agent with a mass ratio of ethylene glycol, benzyl alcohol, and cyclohexanol of (6 - 8):(1 - 2):(1 - 2) is beneficial to maximizing the open porosity and achieving the best connectivity of the material. Ethylene glycol, benzyl alcohol, and cyclohexanol are all non-polar or weakly polar organic substances and do not react with cement, ensuring the stable formation of the pore structure during curing. Moreover, the three have different freezing points and sublimation characteristics, forming crystals of different shapes during freezing and undergoing cross-linking during growth to form internally connected pores and channels, and this structure will be retained after sublimation, making the foam cement-based sound-absorbing material have better pore connectivity and structural stability.

[0024] In this technical solution, during the foaming process, the stability of the foam is very important. Therefore, a shotcrete liquid accelerator is added to the slurry of the cement-based foam, significantly accelerating the setting and hardening process of the foam slurry, stabilizing and fixing the bubbles in a short time, and preventing the collapse of the mold caused by the rupture of the bubbles before they are fixed. At the same time, a foam-stabilizing component is added to the composite foaming agent to make the bubbles generated by the physical-chemical synergistic foaming method stably exist in the slurry, avoiding the situation of overflow or bubble merging.

[0025] Another object of the present invention is to provide a preparation method of a foam cement-based sound-absorbing material with adjustable pore structure, and this method specifically includes the following steps:

[0026] S1. Weigh P.O42.5R portland cement, water, accelerator, microporous structure regulator, and composite pore-forming agent according to the mass ratio, and place them in a high-speed stirrer to stir at a speed of 1500 - 3000 rad / min for 2 - 4 min to obtain a composite cement slurry;

[0027] S2. After adding the composite foaming agent to the composite cement slurry obtained in S1, stir at a speed of 1500 - 3000 rad / min for 30 - 45 s, and then continue to stir at a speed of 6000 - 8000 rad / min for 15 - 25 s to obtain a composite cement-based foam slurry;

[0028] S3. Pour the composite cement-based foam slurry obtained in S2 quickly into a mold, and let it stand and foam for 20 - 48 h in an environment with room temperature (20 - 30 °C) and relative humidity of 50 - 90% to obtain a composite foam cement matrix material;

[0029] S4. Place the fully foamed and solidified composite foam cement matrix material obtained in S3 in a -5 °C freezing device and freeze it for 20 - 36 h to allow the water and the composite pore-forming agent in the composite foam cement matrix material to fully crystallize at low temperature, obtaining a frozen foam cement-based material;

[0030] S5. Use a vacuum freeze dryer to perform freeze drying on the frozen foam cement-based material obtained in S4, with a vacuum degree of 0.1 - 5 Pa and freezing for 20 - 48 h to further complete the regulation of the pore structure;

[0031] S6. Finally, transfer the material obtained in S5 into a standard curing box, and process it to obtain the foam cement-based sound-absorbing material after curing for a specified time.

[0032] In one or more embodiments, pour the composite cement-based foam slurry into a mold with a diameter of 100 mm and a height of 50 mm, and let it stand and foam for 20 - 48 h to make it foam sufficiently. At the same time, enable the composite cement-based foam slurry to form a certain amount of gelling substances through early hydration, so that the cement particles bond to each other, facilitating the subsequent preparation process.

[0033] In some embodiments, place the fully foamed and solidified composite foam cement matrix material in S3 in a -5°C freezing device and freeze for 20 - 36 h. The purpose is to make the water and the composite pore-forming agent in the composite foam cement matrix material crystallize at low temperature. Secondly, choosing -5°C for pre-freezing is to avoid the cement matrix cracking due to too low temperature.

[0034] In some embodiments, place the frozen foam cement-based material obtained in S4 in a vacuum freeze dryer for vacuum freeze drying treatment. The vacuum degree is 0.1 - 5 Pa, and the freeze drying process is divided into three stages. The first stage is -15 - 0°C, and the freeze drying time is 10 - 16 h; the second stage is -30 - -15°C, and the freeze drying time is 6 - 12 h; the third stage is -45 - -30°C, and the freeze drying time is 4 - 8 h. Finally, make the water and the composite pore-forming agent fully crystallize and sublimate to form pores at different temperature zones, while avoiding the cracking of the cement matrix. In the first stage of vacuum freeze drying (-15 - 0°C), the water in the foam cement-based sound-absorbing material is completely sublimated, and part of the benzyl alcohol is sublimated for preliminary pore opening; in the second stage of vacuum freeze drying (-30 - -15°C), the remaining benzyl alcohol and ethylene glycol are sublimated to form stepped pore formation; in the third stage of vacuum freeze drying (-45 - -30°C), cyclohexanol rapidly sublimes to reduce the blockage of the pore walls by the residues. Finally, the water and the composite pore-forming agent in the material completely leave in the form of gas, so that the subsequent hydration in the standard curing box is not affected by it, ensuring the standardization and consistency of the curing conditions and reducing the error of the mechanical properties of the specimens.

[0035] According to the experimental materials and experimental preparation methods of the present invention, this technical solution can obtain foam cement-based sound-absorbing materials with different pore complexity levels: foam cement-based sound-absorbing materials with different density grades, foam cement-based sound-absorbing materials with different pore size coverage ranges and pore ratios under the same density grade, and foam cement-based sound-absorbing materials with different open porosity under the same density grade, ultimately realizing the effective design of the pore structure and sound-absorbing performance of foam cement-based sound-absorbing materials.

[0036] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0037] 1. In the present invention, through the innovative adoption of the physical-chemical synergistic foaming method combined with the vacuum freeze-drying method, and introducing the multi-component synergistic effect of a microporous structure regulator, a composite foaming agent, and a composite pore-forming agent, multi-dimensional regulation of different pore ratios (nm, μm, and mm), different pore size coverage ranges, different porosities, and different open porosities of the foam cement-based sound-absorbing material is achieved, thereby obtaining a foam cement-based sound-absorbing material with low density, high open porosity, and relatively high strength, and then effectively dissipating sound energy. By adjusting the pore structure, not only the harm of noise pollution is effectively reduced, but also the structural characteristics, durability, and low cost characteristics of inorganic mineral building materials are fully utilized;

[0038] 2. The present invention designs a microporous structure regulator, adjusts the dosage and composition ratio of the microporous structure regulator in the foam cement-based sound-absorbing material, and uses the pozzolanic activity of the microporous structure regulator itself to react with cement to increase the strength of the material and cooperate with the vacuum freeze-drying method to sublimate and remove the ice crystals in its own nm-level pores, realizing the regulation of the pore ratio at the nm level of the foam cement-based sound-absorbing material on the premise of having sufficient mechanical properties, and further increasing the porosity and pore complexity;

[0039] 3. The present invention designs a freeze-drying process with three-stage temperature control. Specifically, according to the different freezing points and sublimation characteristics of water and the composite pore-forming agent, a three-stage temperature control (-15~0°C to -30~-15°C and then to -45~-30°C) vacuum freeze-drying process is designed, and the vacuum freeze-drying time at different stages is regulated according to the dosage and composition ratio of the composite pore-forming agent, realizing the full crystallization and sublimation of water and the composite pore-forming agent, and avoiding the damage of the pore structure caused by ice crystal coarsening, achieving high open porosity, thereby increasing the sound absorption capacity of the foam cement-based sound-absorbing material. At the same time, the setting of various experimental condition parameters in the preparation process of the foam cement-based sound-absorbing material is explored, providing a reference for the preparation of new building functional materials. Description of the Drawings

[0040] The accompanying drawings are used to provide a further understanding of the present invention and form a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not limit the embodiments of the present invention. In the accompanying drawings:

[0041] Figure 1 is a process step diagram of a foam cement-based sound-absorbing material with adjustable pore structure and its preparation method provided by the present invention;

[0042] Figure 2 is a physical diagram of a foam cement-based sound-absorbing material with adjustable pore structure provided by the present application;

[0043] Figure 3 is a physical comparison diagram of the surface pore structure of embodiments with different pore diameter coverage ranges under the same density grade provided by the present invention. Detailed Embodiments

[0044] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in combination with embodiments and the accompanying drawings. The illustrative embodiments of the present invention and their descriptions are only used to explain the present invention and do not limit the present invention.

[0045] For all raw materials of the present invention, there are no special restrictions on their sources, and they can be purchased on the market or prepared according to the conventional methods well-known to those skilled in the art;

[0046] For all raw materials of the present invention, there are no special restrictions on their purity, and the present invention preferably uses analytical pure;

[0047] For all raw materials of the present invention, their grades and abbreviations are all conventional grades and abbreviations in the art, and each grade and abbreviation is clear and definite in the field of its relevant uses. Those skilled in the art can purchase them from the market or prepare them through conventional methods according to the grade, abbreviation, and corresponding uses.

[0048] Example 1: By weight, the raw materials include: 1100 parts of P.O42.5R Portland cement, 550 parts of water, 80 parts of a composite foaming agent, 16 parts of a microporous structure regulator, and 8 parts of a quick-setting agent;

[0049] Among them, the main raw materials of the composite foaming agent are 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, and the mass ratio of the 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide is 28:14:6:2;

[0050] Among them, the main raw materials of the microporous structure regulator are sepiolite powder, zeolite powder, and diatomaceous earth, and the mass ratio of the sepiolite powder, zeolite powder, and diatomaceous earth is 7:2:2;

[0051] Among them, the accelerating agent is a liquid accelerating agent for shotcrete.

[0052] The specific steps are as follows:

[0053] (1) Weigh P.O42.5R Portland cement, water, accelerating agent, microporous structure regulator and composite pore-forming agent according to the mass ratio, and place them in a high-speed stirrer to stir at a speed of 2000 rad / min for 3 min to obtain a composite cement paste;

[0054] (2) After adding a composite foaming agent to the composite cement paste obtained in S1, stir at a speed of 1600 rad / min for 35 s, and then continue to stir at a speed of 7600 rad / min for 20 s to obtain a composite cement-based foam paste;

[0055] (3) Quickly pour the composite cement-based foam paste obtained in (2) into a mold, and let it stand and foam for 24 h in an environment with a room temperature of 25 °C and a humidity of 90% to obtain a composite foam cement matrix material;

[0056] (4) Transfer the composite foam cement matrix material obtained in (3) to a standard curing box for curing to the specified time, and then process it to obtain a foam cement-based sound-absorbing material.

[0057] Example 2: By weight, the raw materials include: 1100 parts of P.O42.5R Portland cement, 550 parts of water, 80 parts of composite foaming agent, 22 parts of microporous structure regulator, and 8 parts of accelerating agent;

[0058] Among them, the main raw materials of the composite foaming agent are 30 wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, and the mass ratio of the 30 wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide is 26:11:4:1;

[0059] The remaining steps are the same as those in Example 1.

[0060] Example 3: By weight, the raw materials include: 1100 parts of P.O42.5R Portland cement, 550 parts of water, 80 parts of composite foaming agent, 25 parts of microporous structure regulator, and 8 parts of accelerating agent;

[0061] Among them, the main raw materials of the composite foaming agent are 30 wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, and the mass ratio of the 30 wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide is 25:10:3:1;

[0062] The remaining steps are the same as those in Example 1.

[0063] Example 4: By weight, the raw materials include: 1100 parts of P.O42.5R portland cement, 550 parts of water, 80 parts of composite foaming agent, 30 parts of microporous structure regulator, and 8 parts of quick-setting agent;

[0064] Among them, the main raw materials of the composite foaming agent are 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, and the mass ratio of the 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide is 24:9:2:1;

[0065] The remaining steps are the same as those in Example 1.

[0066] Example 5: By weight, the raw materials include: 1100 parts of P.O42.5R portland cement, 550 parts of water, 80 parts of composite foaming agent, 32 parts of microporous structure regulator, and 8 parts of quick-setting agent;

[0067] Among them, the main raw materials of the composite foaming agent are 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, and the mass ratio of the 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide is 22:8:1:1;

[0068] The remaining steps are the same as those in Example 1.

[0069] Example 6: By weight, the raw materials include: 1100 parts of P.O42.5R portland cement, 550 parts of water, 80 parts of composite foaming agent, 22 parts of microporous structure regulator, 10 parts of composite pore-forming agent, and 8 parts of quick-setting agent;

[0070] Among them, the main raw materials of the composite foaming agent are 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide, and the mass ratio of the 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide is 26:11:4:1;

[0071] Among them, the main raw materials of the microporous structure regulator are sepiolite powder, zeolite powder, and diatomaceous earth, and the mass ratio of the sepiolite powder, zeolite powder, and diatomaceous earth is 7:2:2;

[0072] Among them, the main raw materials of the composite pore-forming agent are ethylene glycol, benzyl alcohol, and cyclohexanol, and the mass ratio of the ethylene glycol, benzyl alcohol, and cyclohexanol is 8:2:1;

[0073] Among them, the quick-setting agent is a shotcrete liquid quick-setting agent.

[0074] The specific steps are as follows:

[0075] (1)Weigh P.O42.5R Portland cement, water, quick-setting agent, microporous structure regulator and composite pore-forming agent according to the mass ratio, and place them in a high-speed stirrer to stir at a speed of 2000 rad / min for 3 min to obtain a composite cement paste;

[0076] (2)After adding the composite foaming agent to the composite cement paste obtained in (1), stir at a speed of 1600 rad / min for 35 s, and then continue to stir at a speed of 7600 rad / min for 20 s to obtain a composite cement-based foam paste;

[0077] (3)Quickly pour the composite cement-based foam paste obtained in (2) into a mold, and let it stand and foam for 24 h in an environment with a room temperature of 25 °C and a humidity of 90% to obtain a composite foam cement matrix material;

[0078] (4)Place the fully foamed and solidified composite foam cement matrix material obtained in (3) in a -5 °C freezing device and freeze it for 20 h to allow the water in the composite foam cement matrix material and the composite pore-forming agent to fully crystallize at low temperature, obtaining a frozen foam cement-based material;

[0079] (5)Use a vacuum freeze dryer to perform vacuum freeze drying on the frozen foam cement-based material obtained in (4), with a vacuum degree of 0.1 Pa. The vacuum freeze drying process is divided into three stages. The first stage is -15~0 °C, and the freeze drying time is 10 h. The second stage is -30~-15 °C, and the freeze drying time is 6 h. The third stage is -45~-30 °C, and the freeze drying time is 4 h, so that the water and the composite pore-forming agent in the frozen foam cement-based material fully crystallize and sublimate, further completing the pore structure regulation;

[0080] (6)Finally, transfer the material obtained in (5) to a standard curing box, and after curing for the specified time, process it to obtain a foam cement-based sound-absorbing material.

[0081] Example 7: By weight, the raw materials include: 1100 parts of P.O42.5R Portland cement, 550 parts of water, 80 parts of composite foaming agent, 22 parts of microporous structure regulator, 14 parts of composite pore-forming agent, and 8 parts of quick-setting agent;

[0082] Among them, in step (5), the frozen foam cement-based material obtained in (4) is subjected to vacuum freeze drying with a vacuum degree of 0.1 Pa. The vacuum freeze drying process is divided into three stages. The first stage is -15~0 °C, and the freeze drying time is 11 h. The second stage is -30~-15 °C, and the freeze drying time is 7 h. The third stage is -45~-30 °C, and the freeze drying time is 5 h, so that the water and the composite pore-forming agent in the frozen foam cement-based material fully crystallize and sublimate, further completing the pore structure regulation;

[0083] The remaining steps are the same as those in Example 6.

[0084] Example 8: By weight, the raw materials include: 1100 parts of P.O42.5R portland cement, 550 parts of water, 80 parts of composite foaming agent, 22 parts of microporous structure regulator, 18 parts of composite pore-forming agent, and 8 parts of accelerating agent;

[0085] Among them, in step (5), the frozen foam cement-based material obtained in (4) is freeze-dried with a vacuum degree of 0.1 Pa. The freeze-drying process is divided into three stages. The first stage is -15~0°C with a freeze-drying time of 11 h, the second stage is -30~-15°C with a freeze-drying time of 8 h, and the third stage is -45~-30°C with a freeze-drying time of 6 h, so that the water in the frozen foam cement-based material and the composite pore-forming agent are fully crystallized and sublimated to further complete the pore structure regulation;

[0086] The remaining steps are the same as those in Example 6.

[0087] Example 9: By weight, the raw materials include: 1100 parts of P.O42.5R portland cement, 550 parts of water, 80 parts of composite foaming agent, 22 parts of microporous structure regulator, 22 parts of composite pore-forming agent, and 8 parts of accelerating agent;

[0088] Among them, in step (5), the frozen foam cement-based material obtained in (4) is freeze-dried with a vacuum degree of 0.1 Pa. The freeze-drying process is divided into three stages. The first stage is -15~0°C with a freeze-drying time of 13 h, the second stage is -30~-15°C with a freeze-drying time of 11 h, and the third stage is -45~-30°C with a freeze-drying time of 6 h, so that the water in the frozen foam cement-based material and the composite pore-forming agent are fully crystallized and sublimated to further complete the pore structure regulation;

[0089] The remaining steps are the same as those in Example 6.

[0090] Example 10: By weight, the raw materials include: 1100 parts of P.O42.5R portland cement, 550 parts of water, 80 parts of composite foaming agent, 22 parts of microporous structure regulator, 26 parts of composite pore-forming agent, and 8 parts of accelerating agent;

[0091] Among them, in step (5), the frozen foam cement-based material obtained in (4) is freeze-dried with a vacuum degree of 0.1 Pa. The freeze-drying process is divided into three stages. The first stage is -15~0°C with a freeze-drying time of 15 h, the second stage is -30~-15°C with a freeze-drying time of 12 h, and the third stage is -45~-30°C with a freeze-drying time of 7 h, so that the water in the frozen foam cement-based material and the composite pore-forming agent are fully crystallized and sublimated to further complete the pore structure regulation;

[0092] The remaining steps are the same as those in Example 6.

[0093] Example 11: After preparing the foam cement-based sound-absorbing materials P1 to P10 through Examples 1 to 10, the sound-absorbing performance and mechanical properties of the foam cement-based sound-absorbing materials were tested by an impedance tube and a universal testing machine respectively. The average sound-absorbing coefficient, noise reduction coefficient, and compressive strength of the foam cement-based sound-absorbing materials with different pore structures are shown in Table 1.

[0094] Table 1:

[0095]

[0096] As can be seen from Table 1, by adding appropriate components such as a composite foaming agent, a microporous structure regulator, a composite pore-forming agent, and a quick-setting agent to cement, a foam cement-based sound-absorbing material with adjustable pore structure can be obtained. By adjusting the pore structure, the ability of the material to attenuate sound waves can be greatly improved, which not only effectively reduces the harm of noise pollution but also fully exerts the structural characteristics, durability, and low cost of inorganic mineral building materials. When the density of the foam cement-based sound-absorbing material is 400 kg / m 3 , the total porosity is 82.8%, and the open porosity is 73.1%, the 28-day compressive strength is 2.98 MPa, the average sound-absorbing coefficient reaches 0.62, and the noise reduction coefficient reaches 0.64. The realization of the adjustability of the pore structure has specifically and effectively improved the sound-absorbing performance of the foam cement-based sound-absorbing material.

[0097] The specific embodiments described above have further elaborated on the purpose, technical solutions, and beneficial effects of the present invention. It should be understood that the above are only specific embodiments of the present invention and are not used to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A foam cement-based sound-absorbing material with adjustable pore structure, characterized in that, Its raw materials by weight include: 1000 - 1300 parts of P.O42.5R portland cement, 400 - 600 parts of water, 20 - 100 parts of composite foaming agent, 10 - 35 parts of micro - pore structure regulator, 5 - 30 parts of composite pore - forming agent, and 1 - 20 parts of quick - setting agent; among them, the composite foaming agent takes 30wt.% hydrogen peroxide solution, potassium dodecyl phosphate, calcium stearate, and coconut oil diethanolamide as main raw materials, and they are weighed respectively according to the mass ratio of (22 - 28):(8 - 14):(1 - 6):(1 - 3) and then stirred and mixed evenly; the micro - pore structure regulator takes sepiolite powder, zeolite powder, and diatomite as main raw materials, and they are weighed respectively according to the mass ratio of (7 - 12):(1 - 5):(2 - 3) and then stirred and mixed evenly, and placed in excessive water and soaked until saturated, and then filtered; the composite pore - forming agent takes ethylene glycol, benzyl alcohol, and cyclohexanol as main raw materials, and they are weighed respectively according to the mass ratio of (6 - 8):(1 - 2):(1 - 2) and then mixed evenly.

2. The preparation method of a porous structure adjustable foam cement-based sound-absorbing material according to claim 1, characterized in that, It includes the following steps: S1. Weigh P.O42.5R portland cement, water, quick - setting agent, micro - pore structure regulator, and composite pore - forming agent according to the mass ratio, and place them in a high - speed stirrer and stir at a speed of 1500 - 3000 rad / min for 2 - 4 min to obtain a composite cement paste; S2. After adding the composite foaming agent to the composite cement paste obtained in S1, stir at a speed of 1500 - 3000 rad / min for 30 - 45 s, and then continue to stir at a speed of 6000 - 8000 rad / min for 15 - 25 s to obtain a composite cement - based foam paste; S3. Pour the composite cement - based foam paste obtained in S2 quickly into a mold, and let it stand and foam for 20 - 48 h in an environment with room temperature (20 - 30°C) and relative humidity of 50 - 90% to obtain a composite foam cement matrix material; S4. Place the fully foamed and solidified composite foam cement matrix material obtained in S3 in a - 5°C freezing device and freeze for 20 - 36 h to make the water in the composite foam cement matrix material and the composite pore - forming agent fully crystallize at low temperature to obtain a frozen foam cement - based material; S5. Use a vacuum freeze - dryer to freeze - dry the frozen foam cement - based material obtained in S4, with a vacuum degree of 0.1 - 5 Pa and freeze for 20 - 48 h to further complete the regulation of the pore structure; S6. Finally, transfer the material obtained in S5 to a standard curing box, and after curing for the specified time, process it to obtain a foam cement - based sound - absorbing material.

3. The preparation method of a foam cement-based sound-absorbing material with adjustable pore structure according to claim 2, characterized in that In the step S5, it specifically includes the following steps: The freeze-dried foam cement-based material obtained in S4 is placed in a vacuum freeze dryer for vacuum freeze-drying treatment. The freeze-drying process is divided into three stages. The first stage is at -15 to 0 °C, and the freeze-drying time is 10 to 16 h; the second stage is at -30 to -15 °C, and the freeze-drying time is 6 to 12 h; the third stage is at -45 to -30 °C, and the freeze-drying time is 4 to 8 h. Finally, water and the composite pore-forming agent are fully crystallized and sublimated to form pores at different temperature zones, while avoiding cracking of the cement matrix.

4. The preparation method of a foam cement-based sound-absorbing material with adjustable pore structure according to claim 2, characterized in that The proportion of nm-scale micropores in the material is regulated by adjusting the dosage and composition ratio of the microporous structure regulator; the density, total porosity, and the proportion of pores at the μm and mm scales in the material are regulated by adjusting the dosage and composition ratio of the composite foaming agent; and the open porosity of the material is mainly regulated by adjusting the dosage, composition ratio of the composite pore-forming agent, and the freeze-drying process parameters, ultimately realizing the effective design of the pore structure and sound absorption performance of the foam cement-based material.

5. A foam cement-based sound-absorbing material with adjustable pore structure obtained by the preparation method of the foam cement-based sound-absorbing material with adjustable pore structure according to any one of claims 2 to 4, characterized in that, The density of the foam cement-based sound-absorbing material with adjustable pore structure is 200~1000 kg / m 3 , the thickness is 20~60 mm, the porosity is 60~90%, the pore size coverage range is 2 nm~6 mm, the open porosity is 70~85%, the 28-day compressive strength is 1.83~14.56 MPa, the average sound absorption coefficient in the frequency range of 250~2000 Hz is 0.12~0.62, and the noise reduction coefficient is 0.14~0.64.

Images