Lightweight high-strength foamed concrete and method for preparing the same

Abstract

The application relates to the technical field of building materials, in particular to a light-weight high-strength foamed concrete and a preparation method thereof. The light-weight high-strength foamed concrete is prepared from the following components in parts by weight: cement 1000 parts, a surface active agent 5-30 parts and a breakable self-repairing hydrogel 800-2200 parts. The breakable self-repairing hydrogel is broken into particles and has fluidity during stirring, so that the cement and the surface active agent are fully dispersed; when the stirring is stopped, the hydrogel particles are re-coagulated, the air, the cement and the surface active agent brought in during the stirring are all locked, the'structural water' in the hydrogel gradually and slowly reacts with the cement, the subsequent drying promotes the water loss and shrinkage of the hydrogel network, micron-scale holes are formed, and the foamed concrete material with the light weight, the high strength and the excellent heat preservation performance is successfully prepared.

Description

Technical Field

[0001] This application relates to the field of building materials technology, specifically to a lightweight, high-strength foamed concrete and its preparation method. Background Technology

[0002] Foamed concrete (also known as foamed cement / foamed concrete) is a lightweight porous material. It also has the advantages of heat insulation, fire resistance and sound insulation. It is an energy-saving and environmentally friendly building material and is widely used in building insulation, structural load reduction and engineering backfilling.

[0003] Foamed concrete is typically prepared by incorporating air-water based foam precursors into cementitious slurry to form a porous bubble structure. During the mixing and static hardening stages, the stability of the bubbles in the system is affected by several factors: ① Oswald curing: Small bubbles, due to their small radius of curvature and high Laplace pressure, gradually dissolve and diffuse into larger bubbles through the liquid phase, leading to bubble coarsening and an increase in average diameter. ② Cohesion: Multiple small bubbles come into contact with each other and merge to form larger bubbles. ③ Drainage: The liquid film between bubbles thins or even ruptures due to drainage, further exacerbating bubble cohesion. These processes cause problems such as increased pore size and wider pore diameter distribution in foamed concrete, significantly reducing its macroscopic mechanical properties and greatly limiting its large-scale application in load-bearing structures. Summary of the Invention

[0004] To address the problem of large air bubbles forming in foamed concrete, leading to increased pore size and wider pore distribution, which significantly reduces its macroscopic mechanical properties, this application provides a lightweight, high-strength foamed concrete and its preparation method. The method primarily involves replacing water with a breakable, self-healing hydrogel. During stirring, the breakable, self-healing hydrogel breaks into particles and remains fluid, thus fully dispersing cement and surfactants. When stirring stops, the hydrogel particles re-coagulate, locking in the air, cement, and surfactants introduced during stirring. The "structural water" in the hydrogel gradually and slowly undergoes a hydration reaction with the cement. Subsequent drying promotes the hydrogel network to lose water and shrink, forming micron-scale pores. These factors work together to successfully prepare a foamed concrete material that combines lightweight, high strength, and excellent thermal insulation properties.

[0005] In the first aspect, this application provides a lightweight, high-strength foamed concrete, which adopts the following technical solution:

[0006] A lightweight, high-strength foamed concrete, the raw materials of which include the following components by weight: 1000 parts cement, 5-30 parts surfactant, and 800-2200 parts breakable self-healing hydrogel.

[0007] By adopting the above technical solution, the characteristic of the breakable self-healing hydrogel is that it breaks into fine particles when stirred at high speed, and when stirring stops, the fine particles reconnect and repair themselves, repeatedly forming a hydrogel. Breakable self-healing hydrogels include, but are not limited to, polyacrylamide hydrogels, whose comonomers can be replaced with acrylic acid (AA), 2-acrylamide-2-methylpropanesulfonic acid (AMPS); polymethacrylic acid (PMAA) and its salts (such as sodium and potassium salts) hydrogels; and breakable polyvinyl alcohol-based PVA hydrogels formed through borate ester crosslinking, freeze-thaw cycle physical crosslinking, etc. Natural polymer hydrogel systems can also be used as materials in this application, including polysaccharides: such as sodium alginate (through Ca... 2+ 、Sr 2+ Hydrogels can be formed using various methods, including: thermally reversible or ionicly crosslinked gels such as carrageenan, gellan gum, and xanthan gum; and decomposable gels formed from proteins such as gelatin, collagen, and silk fibroin through thermally reversible or chemical crosslinking. Other natural products, such as chitosan and starch-modified gels, can also be used as hydrogel systems in this application.

[0008] When cement, surfactant, and breakable self-healing hydrogel are stirred together, the breakable self-healing hydrogel first breaks down into tiny particles, significantly reducing the system viscosity and exhibiting good fluidity. Cement and surfactant are then uniformly dispersed between the gel particles. During stirring, air is entrained into the system, forming bubbles. The surfactant is rapidly adsorbed at the gas-liquid interface, forming a dense and stable monomolecular film, thus initially solidifying the bubbles.

[0009] After stirring ceases, the hydrogel particles rapidly self-heal through chain diffusion, entanglement, and hydrogen bonding, reconstructing a continuous three-dimensional network structure. The reconstructed hydrogel network physically encapsulates, anchors, and separates air bubbles, providing them with strong steric stabilization. This, combined with the chemical bubble-stabilizing effect of surfactants, achieves exceptional bubble stability.

[0010] Over time, the "structural water" in the hydrogel continuously and slowly migrates to the surface of the cement particles, triggering and supporting them to complete the full hydration reaction, gradually forming a robust skeleton of hydration products. After the hydration reaction is completed, the hydrogel network loses water and shrinks, releasing its original water-locking space and forming some micron-scale pores in situ, thus successfully preparing a foamed concrete material that combines lightweight, high strength, and excellent thermal insulation properties.

[0011] This application utilizes a self-healing hydrogel that breaks down into particles during mixing while maintaining fluidity, thereby fully dispersing cement and surfactants. When mixing stops, the hydrogel particles re-coagulate, locking in the air, cement, and surfactants introduced during mixing. The "structural water" in the hydrogel gradually and slowly undergoes a hydration reaction with the cement. Subsequent drying promotes the hydrogel network to lose water and shrink, forming micron-scale pores. Through this synergistic process, a foamed concrete material with lightweight, high strength, and excellent thermal insulation properties has been successfully prepared.

[0012] Preferably, the breakable self-healing hydrogel raw material comprises the following components in parts by weight: 4 parts acrylamide, 0.15-0.25 parts potassium persulfate, 0.2-1.6 parts N,N'-methylenebisacrylamide, and 110-130 parts water.

[0013] By employing the above technical solution, acrylamide is the main reactant forming the polymer network backbone, and potassium persulfate is the initiator of the system reaction. Upon heating, potassium persulfate decomposes to generate free radicals, initiating the polymerization of acrylamide to form polyacrylamide molecular chains. N,N'-methylenebisacrylamide is the crosslinking agent; its double bond structure can connect multiple polyacrylamide molecular chains to form a three-dimensional network structure, turning the solution into a gel.

[0014] The breakable mechanism originates from the highly cross-linked network structure within the hydrogel. The prepared breakable self-healing hydrogel, due to its high cross-linking density, exhibits significantly enhanced elastic modulus and yield stress, i.e., high macroscopic stiffness. This mechanical property prevents plastic flow; under the shear force provided by specific external mechanical stirring, its network structure undergoes brittle fracture rather than ductile deformation, thus breaking into particles of a specific size.

[0015] Preferably, the breakable self-healing hydrogel material further includes N,N,N',N'-tetramethylethylenediamine.

[0016] By adopting the above technical solution, N,N,N',N'-tetramethylethylenediamine can be used as an accelerator to form a redox system with potassium persulfate, which significantly reduces the decomposition temperature of the initiator, enabling it to rapidly initiate the polymerization reaction at room temperature.

[0017] Preferably, the preparation method of the breakable self-healing hydrogel includes the following steps:

[0018] Mixing: Mix the prescribed amounts of acrylamide, potassium persulfate, N,N'-methylenebisacrylamide, and water to form the reaction matrix;

[0019] Reaction: N,N,N',N'-tetramethylethylenediamine was added dropwise to the reaction matrix to obtain a breakable self-healing hydrogel.

[0020] Preferably, the surfactant includes at least one of sodium α-alkenyl sulfonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, betaine surfactant, and saponin.

[0021] By employing the above technical solution, the surfactant has a hydrophilic head at one end and a hydrophobic tail at the other, with the hydrophobic tail designed to escape the aquatic environment. In a system where the surfactant, hydrogel, and bubbles coexist, the surfactant may exhibit two orientations: ① the hydrophobic tail faces the air; ② the hydrophobic tail faces the hydrophobic microregions of the hydrogel framework. It is more likely that the tail will face the interior of the bubble to minimize the system's free energy. The direct hydrophobic interaction between the hydrogel and the surfactant is not the dominant mechanism for bubble stabilization. The core role of the hydrogel lies in its ability to significantly increase bulk viscosity to suppress liquid film drainage and indirectly enhance the mechanical properties of the interfacial film by forming a polymer network at the interface. Thus, it works synergistically with the surfactant to construct a highly stable foam system.

[0022] Surfactants are highly sensitive to the high alkalinity and high calcium ion concentration environment of cement, and can rapidly degrade due to chemical reactions. The performance of surfactants primarily depends on the inherent characteristics of their ionic type. Nonionic surfactants are the most robust because they are uncharged, unaffected by high-valence ions, and have the best compatibility. The stability of anionic surfactants depends on the ability of their hydrophilic groups to resist calcium ion precipitation; their tolerance varies, making them a key and challenging aspect of selection. Cationic surfactants are absolutely contraindicated because they strongly adsorb onto negatively charged cement particles, severely disrupting the cement's setting and hardening process. Therefore, in cement systems, the order of surfactant tolerance is generally: nonionic > anionic surfactants with specific structures >> cationic surfactants. Although sodium α-alkenyl sulfonate is an anionic surfactant, the sulfonate group in its molecule is susceptible to divalent cations (such as Ca2+). 2+ It exhibits extremely high tolerance and is very difficult to form insoluble calcium salts. This means that it can ignore the interference of high concentrations of calcium ions in cement pore liquid and maintain its high foaming capacity.

[0023] Secondly, this application provides a method for preparing lightweight high-strength foamed concrete, employing the following technical solution:

[0024] A method for preparing lightweight high-strength foamed concrete, comprising the following steps:

[0025] S1: Add the cement and surfactant of the formula to the breakable self-healing hydrogel, and then stir at a stirring speed of at least 500 rpm to obtain a mixture;

[0026] S2: Stop mixing, pour and cure the mixture, and then dry to obtain lightweight, high-strength foamed concrete.

[0027] By employing the above technical solution, at a stirring rate of at least 500 rpm, the breakable self-healing hydrogel is broken into tiny particles of 40-80 μm. During the breakage process, friction and sliding occur between the particles, leading to a significant decrease in the system viscosity and an inversion (from a high-viscosity solid-like state to a low-viscosity fluid, exhibiting good fluidity). Cement and surfactants are uniformly dispersed between the gel particles. Simultaneously, high-speed stirring entrains air into the system, forming bubbles; the pre-added surfactant in the system is rapidly adsorbed at the gas-liquid interface, forming a dense and stable monomolecular film, initially solidifying the bubbles.

[0028] After stirring ceases, the system is removed from the shear environment, and the hydrogel particles rapidly self-heal through chain diffusion, entanglement, and hydrogen bonding, reconstructing a continuous three-dimensional network structure. This process is accompanied by an instantaneous recovery of the system's viscosity, followed by another reversal, restoring its solid-like rheological behavior. The reconstructed hydrogel network physically encapsulates, anchors, and separates air bubbles, providing them with strong steric stabilization. This, combined with the chemical bubble-stabilizing effect of surfactants, achieves exceptional bubble stability.

[0029] Cement particles and air bubbles are uniformly fixed within the hydrogel framework. Over time, based on the humidity gradient between the interior and exterior surfaces of the cement particles, the "structural water" locked within the network acts as a slow-release water source, continuously and slowly migrating to the surface of the cement particles, triggering and supporting them to complete a full hydration reaction, and gradually forming a robust framework of hydration products.

[0030] After the cement hydration reaction is basically complete, the system is dried at low temperature to remove residual moisture. The hydrogel network shrinks as it loses water; as an organic component, it ultimately exists in a thin film form between the cement hydration products, playing a certain toughening role. Its original water-locking spaces are released, forming some micron-scale pores in situ. Finally, a foamed concrete material with lightweight, high strength, and excellent thermal insulation properties is successfully prepared.

[0031] Preferably, in step S1, the stirring rate is 2000-3000 rpm.

[0032] By employing the above technical solution, the main purpose of stirring is dispersion and foam initiation. However, under fixed surfactant concentration and conditions, regardless of the shear rate, the introduced foam volume has a cap, which is determined by the amount of surfactant used. Once the capped foam volume is reached, stirring is stopped, and the hydrogel returns to its static rheological state. At this point, foam stability is no longer related to the stirring rate. The stirring rate primarily determines the foam initiation rate; a stirring rate of 2000-3000 rpm can quickly bring the introduced foam volume to its maximum value.

[0033] Preferably, step S1 further includes adding nanofillers to the breakable self-healing hydrogel and stirring them together. The nanofillers include at least one of lithium saponite, nanocellulose, nanosilica, and carbon nanotubes.

[0034] By employing the above technical solutions, nanomaterials, due to their extremely high specific surface area and surface energy, are prone to irreversible aggregation and sedimentation in aqueous phases, forming aggregates that are difficult to redisperse. Therefore, when nanofillers are directly miscible with water, this uneven dispersion state severely restricts their functionality (such as reinforcement and conductivity) and becomes a performance defect in the final product.

[0035] When nanofillers are blended with breakable self-healing hydrogels, mechanical stirring is applied to induce shear force that breaks down the gel particles. This process not only allows the newly exposed gel interface to efficiently adsorb nanounits, but the gel fragments generated by the breakage also act as an instantaneously generated micron-level physical barrier, effectively isolating and preventing the re-aggregation of nanoparticles. Thus, the dissociation of the gel carrier and the efficient and stable dispersion of nanomaterials are achieved simultaneously in a single operation.

[0036] In summary, this application has the following beneficial effects:

[0037] 1. Because this application uses a breakable self-healing hydrogel that breaks into particles and has fluidity during mixing, it can fully disperse cement and surfactants. When mixing stops, the hydrogel particles re-coagulate, locking in the air, cement and surfactants introduced during mixing. The "structural water" in the hydrogel gradually and slowly undergoes a hydration reaction with the cement. Subsequent drying promotes the hydrogel network to lose water and shrink, forming micron-scale pores. Together, they successfully prepare a foamed concrete material that combines lightweight, high strength and excellent thermal insulation properties.

[0038] 2. The surfactant used in this application is preferably nonionic, because nonionic surfactants are the most robust, are uncharged, are not affected by high-valence ions, and have the best compatibility; or sodium α-alkenyl sulfonate can be used, which can ignore the interference of high concentration of calcium ions in cement pore liquid and always maintain high foaming ability.

[0039] 3. The preparation of lightweight high-strength foamed concrete in this application can also add nanofillers, because the gel fragments generated by the crushing can effectively isolate and prevent the re-aggregation of nanoparticles, thereby achieving the dissociation of the gel carrier and the efficient and stable dispersion of nanomaterials in a single operation. Detailed Implementation

[0040] The raw materials in this application include the following:

[0041] Cement: Silicate cement, chlorate cement, sulfoaluminate cement, etc. are all acceptable. This application only uses P·I 52.5 grade Silicate cement as an example.

[0042] Sodium α-alkenylsulfonate: Uses a commercially available product with CAS number 68439-57-6;

[0043] Sodium dodecyl sulfate: Use commercially available product with CAS number 151-21-3;

[0044] Fatty alcohol polyoxyethylene ether: There are many variations. This application only uses a commercially available product with CAS number 111-09-3 as an example.

[0045] Betaine surfactants include cocamidopropyl betaine and dodecyl betaine. This application only uses commercially available cocamidopropyl betaine with CAS number 61789-40-0 as an example.

[0046] Saponins: Use commercially available products with CAS number 8047-15-2;

[0047] Acrylamide: Use commercially available products with CAS number 79-06-1;

[0048] Potassium persulfate: Commercially available product with CAS number 7727-21-1 is used;

[0049] N,N'-Methylenebisacrylamide: Use commercially available products with CAS number 110-26-9;

[0050] N,N,N',N'-Tetramethylethylenediamine: Use the commercially available product with CAS number 110-18-9;

[0051] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0052] Example 1

[0053] A method for preparing a breakable self-healing hydrogel includes the following steps:

[0054] Mixing: Mix 4g acrylamide, 0.2g potassium persulfate (0.15g-0.25g is acceptable), 1g N,N'-methylenebisacrylamide and 120g water (110g-130g is acceptable) to form the reaction matrix;

[0055] Reaction: 120 μL of N,N,N',N'-tetramethylethylenediamine was added dropwise to the reaction matrix to obtain a breakable self-healing hydrogel.

[0056] A method for preparing lightweight, high-strength foamed concrete includes the following steps:

[0057] S1: Add 1000g of cement and 5g of sodium α-alkenyl sulfonate to 835g of breakable self-healing hydrogel, and then stir at a stirring speed of 2000rpm for 3min to obtain a mixture.

[0058] S2: Stop stirring, pour the mixture into the mold, vibrate to remove large air bubbles, and cure for 28 days under standard curing conditions of 20±1℃ and humidity>95%. Then, place the cured test blocks in a 60℃ forced-air oven to dry to constant weight to obtain lightweight high-strength foamed concrete.

[0059] The specific amount of breakable self-healing hydrogel added is adjusted according to the target water-cement ratio. For example, if the target water-cement ratio in Example 1 is 0.8, then the required amount of water is 800g. The water content of the breakable self-healing hydrogel is 95.8%, so the amount of breakable self-healing hydrogel added is 800 / 95.8%≈835g.

[0060] Example 2

[0061] A method for preparing a breakable self-healing hydrogel includes the following steps:

[0062] Mixing: Mix 4g acrylamide, 0.2g potassium persulfate, 1g N,N'-methylenebisacrylamide and 120g water to form the reaction matrix;

[0063] Reaction: 120 μL of N,N,N',N'-tetramethylethylenediamine was added dropwise to the reaction matrix to obtain a breakable self-healing hydrogel.

[0064] A method for preparing lightweight, high-strength foamed concrete includes the following steps:

[0065] S1: Add 500g of cement and 15g of sodium α-alkenyl sulfonate to 1044g of breakable self-healing hydrogel, and then stir at a stirring speed of 2000rpm for 3min to obtain a mixture.

[0066] S2: Stop stirring, pour the mixture into the mold, vibrate to remove large air bubbles, and cure for 28 days under standard curing conditions of 20±1℃ and humidity>95%. Then, place the cured test blocks in a 60℃ forced-air oven to dry to constant weight to obtain lightweight high-strength foamed concrete.

[0067] The specific amount of breakable self-healing hydrogel added is adjusted according to the target water-cement ratio. For example, if the target water-cement ratio in Example 1 is 2.0, then the required amount of water is 1000g. The water content of the breakable self-healing hydrogel is 95.8%, so the amount of breakable self-healing hydrogel added is 1000 / 95.8%≈1044g.

[0068] Comparative Examples 1-2

[0069] Comparative Example 1, based on the preparation method of Example 1, includes the following steps:

[0070] S1: Add 1000g of cement and 5g of sodium α-olefin sulfonate to 800g of water, then stir at a stirring speed of 2000rpm for 3min to obtain a mixture;

[0071] S2: Stop stirring, pour the mixture into the mold, vibrate to remove large air bubbles, and cure for 28 days under standard curing conditions of 20±1℃ and humidity>95%. Then, place the cured test blocks in a 60℃ forced-air oven to dry to constant weight to obtain lightweight high-strength foamed concrete.

[0072] Comparative Example 2, based on the preparation method of Example 2, includes the following steps:

[0073] S1: Add 500g of cement and 15g of sodium α-olefin sulfonate to 1000g of water, then stir at a stirring speed of 2000rpm for 3min to obtain a mixture;

[0074] S2: Stop stirring, pour the mixture into the mold, vibrate to remove large air bubbles, and cure for 28 days under standard curing conditions of 20±1℃ and humidity>95%. Then, place the cured test blocks in a 60℃ forced-air oven to dry to constant weight to obtain lightweight high-strength foamed concrete.

[0075] Performance testing

[0076] The lightweight high-strength foamed concrete of Examples 1-2 and Comparative Examples 1-2 were subjected to the following performance tests, and the test results are shown in Table 1.

[0077] The density, compressive strength and thermal conductivity of lightweight high-strength foamed concrete were determined according to GB / T 29062-2012 Foamed Concrete.

[0078] Table 1. Content and performance test results of each component in lightweight high-strength foamed concrete of Examples 1-2 and Comparative Examples 1-2.

[0079]

[0080] Referring to Table 1, comparing Examples 1-2 and Comparative Examples 1-2, it can be seen that when the water-cement ratio is 0.8, this application utilizes the breakable self-healing hydrogel to prepare a lightweight high-strength foamed concrete with moderate density, high compressive strength, and excellent thermal insulation performance, suitable for integrated load-bearing and thermal insulation components in buildings. When the water-cement ratio is 2.0, this application can prepare an ultra-lightweight, highly insulating, and relatively strong lightweight high-strength foamed concrete, suitable for exterior wall insulation layers in buildings. If the breakable self-healing hydrogel is replaced with water, the prepared concrete, due to its high water-cement ratio, is prone to bleeding and settling, disrupting the system's stability and easily cracking.

[0081] Examples 3-5

[0082] Example 3, based on the preparation method of Example 1, adjusts the preparation method of the breakable self-healing hydrogel as follows:

[0083] 4g of acrylamide, 0.2g of potassium persulfate, 1g of N,N'-methylenebisacrylamide and 120g of water were mixed and then heated at 75°C to obtain a breakable self-healing hydrogel.

[0084] Examples 4-5 are based on the preparation method of Example 1, but the content of N,N'-methylenebisacrylamide is adjusted. The specific adjustments are shown in Table 2.

[0085] The lightweight high-strength foamed concrete of Examples 3-5 were subjected to the above performance tests, and the test results are shown in Table 2.

[0086] Table 2. Content and performance test results of N,N'-methylenebisacrylamide in Examples 1 and 3-5.

[0087]

[0088] Referring to Table 2, a comparison of Examples 1 and 3-5 shows that when the amount of N,N'-methylenebisacrylamide added is greater than 0.1 g, a cross-linked network sufficient to resist plastic flow can be formed, giving the hydrogel breakable properties. Generally, within the stated ratio range, as the amount of N,N'-methylenebisacrylamide increases, the cross-linking density of the hydrogel continuously increases, the network stiffness is enhanced, and it is more prone to breakage under mechanical shearing. However, it should be noted that excessively high cross-linking density will, to some extent, restrict the mobility of polymer chain segments, thereby weakening its self-healing properties and reducing its stabilizing effect on bubbles.

[0089] Examples 6-9

[0090] Examples 6-9 are based on the preparation method of Example 1, but the types of surfactants are adjusted. The specific adjustments are shown in Table 3.

[0091] The lightweight high-strength foamed concrete of Examples 6-9 were subjected to the above performance tests, and the test results are shown in Table 3.

[0092] Table 3. Types of surfactants and performance test results for Examples 1 and 6-9.

[0093]

[0094] Referring to Table 3, a comparison of Examples 1 and 6-9 shows that anionic surfactants, nonionic surfactants, amphoteric surfactants, and biological protein surfactants can all be used. Nonionic surfactants are the most robust because they are uncharged and unaffected by high-valence ions, exhibiting the best compatibility. The stability of anionic surfactants depends on the ability of their hydrophilic groups to resist calcium ion precipitation, resulting in varying tolerances. While sodium α-alkenyl sulfonate is an anionic surfactant, the sulfonate group in its molecule is sensitive to divalent cations (such as Ca2+). 2+ It exhibits extremely high tolerance and is very difficult to form insoluble calcium salts. This means that it can ignore the interference of high concentrations of calcium ions in cement pore liquid and maintain its high foaming capacity.

[0095] Examples 10-11

[0096] Examples 10-11 are based on the preparation method of Example 1, but the stirring rate and stirring time are adjusted. The specific adjustments are shown in Table 4.

[0097] Comparative Examples 3-4

[0098] Comparative Examples 3-4 were prepared using the same method as in Example 1, but with adjustments to the stirring rate and stirring time. The specific adjustments are shown in Table 4.

[0099] The lightweight high-strength foamed concrete of Examples 10-11 and Comparative Examples 3-4 were subjected to the above performance tests, and the test results are shown in Table 4.

[0100] Table 4. Stirring rate, stirring time, and performance test results for Examples 1, 10-11, and Comparative Examples 3-4.

[0101]

[0102] Referring to Table 4, comparing Examples 1, 10-11, and 3-4, it can be seen that the main purpose of stirring is dispersion and foam initiation. However, under fixed surfactant concentration and conditions, regardless of the shear rate, the introduced foam volume has a cap, which is determined by the amount of surfactant used. Once the capped foam volume is reached, stirring is stopped, and the hydrogel returns to its static rheological state. At this point, the stable foam volume is no longer related to the stirring rate. The stirring rate mainly determines the speed of foam initiation. Therefore, low stirring rates require longer stirring times, while high stirring rates, such as 2000-3000 rpm, can quickly bring the introduced foam volume to its maximum value.

[0103] Examples 12-13

[0104] Example 12, based on the preparation method of Example 1, adjusts the preparation method of lightweight high-strength foamed concrete as follows:

[0105] S1: Add 1000g of cement, 5g of sodium α-olefin sulfonate, and 5g of nano-silica to 835g of breakable self-healing hydrogel, and then stir at a stirring speed of 2000rpm for 3min to obtain a mixture.

[0106] S2: Stop stirring, pour the mixture into the mold, vibrate to remove large air bubbles, and cure for 28 days under standard curing conditions of 20±1℃ and humidity>95%. Then, place the cured test blocks in a 60℃ forced-air oven to dry to constant weight to obtain lightweight high-strength foamed concrete.

[0107] Example 13 is based on the preparation method of Example 12, except that nano-silica is replaced with carbon nanotubes. Lithium saponite and nanocellulose can also be used in this application; Examples 12-13 are only illustrative examples using nano-silica and carbon nanotubes.

[0108] The lightweight high-strength foamed concrete of Examples 12-13 were subjected to the above performance tests, and the test results are shown in Table 5.

[0109] Table 5. Types of nanofillers and performance test results for Examples 1 and 12-13.

[0110]

[0111] Referring to Table 5, a comparison of Examples 1 and 12-13 shows that adding nanofillers to lightweight, high-strength foamed concrete further improves its performance. This is because the added nanofillers can adsorb onto the bubble interface, forming a three-dimensional barrier with high mechanical strength, inhibiting bubble aggregation and Oswald curing. When the nanofillers are blended with a breakable self-healing hydrogel, mechanical stirring is applied, utilizing shear force to cause the gel particles to break down. This process not only allows the newly exposed gel interface to efficiently adsorb nanounits, but the gel fragments generated by the breakage also act as an instantaneously generated micron-level physical barrier, effectively isolating and preventing the re-aggregation of nanoparticles. Thus, in a single operation, the dissociation of the gel carrier and the efficient and stable dispersion of nanomaterials are simultaneously achieved.

[0112] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A lightweight, high-strength foamed concrete, characterized in that, The raw materials include the following components by weight: 1000 parts cement, 5-30 parts surfactant, and 800-2200 parts breakable self-healing hydrogel; The breakable self-healing hydrogel raw material comprises the following components in parts by weight: 4 parts acrylamide, 0.15-0.25 parts potassium persulfate, 0.2-1.6 parts N,N'-methylenebisacrylamide, and 110-130 parts water; The surfactant includes at least one of sodium α-alkenyl sulfonate, sodium dodecyl sulfate, fatty alcohol polyoxyethylene ether, betaine surfactants, and saponins.

2. The lightweight high-strength foamed concrete according to claim 1, characterized in that: The breakable self-healing hydrogel material also includes N,N,N',N'-tetramethylethylenediamine.

3. The lightweight high-strength foamed concrete according to claim 2, characterized in that: The preparation method of the breakable self-healing hydrogel includes the following steps: Mixing: Mix the prescribed amounts of acrylamide, potassium persulfate, N,N'-methylenebisacrylamide, and water to form the reaction matrix; Reaction: N,N,N',N'-tetramethylethylenediamine was added dropwise to the reaction matrix to obtain a breakable self-healing hydrogel.

4. The method for preparing lightweight high-strength foamed concrete according to any one of claims 1-3, characterized in that, Includes the following steps: S1: Add the cement and surfactant of the formula to the breakable self-healing hydrogel, and then stir at a stirring speed of at least 500 rpm to obtain a mixture; S2: Stop mixing, pour and cure the mixture, and then dry to obtain lightweight, high-strength foamed concrete.

5. The method for preparing lightweight high-strength foamed concrete according to claim 4, characterized in that: In step S1, the stirring speed is 2000-3000 rpm.

6. The method for preparing lightweight high-strength foamed concrete according to claim 4, characterized in that: In step S1, the nanofiller is added to the breakable self-healing hydrogel and stirred together. The nanofiller includes at least one of lithium saponite, nanocellulose, nanosilica, and carbon nanotubes.

Images