Ultrafine particle powder and fiber reinforced composite foam concrete and preparation method thereof

Abstract

The invention provides superfine particle powder and fiber reinforced composite foam concrete and a preparation method thereof, and belongs to the field of special engineering structure protection materials. The foam concrete is prepared from the following raw materials in parts by weight: 220 to 320 parts of ultrafine particle composite powder, 0.5 to 7 parts of fiber reinforcement, 0.5 to 1.5 parts of high-performance water-reducing mother liquid, 1 to 2 parts of calcium sulphoaluminate, 80 to 120 parts of water and a plurality of foams, wherein the plurality of foams depend on the designed volume weight of the foam concrete. The high-performance fiber foam concrete with the apparent density of 849 kg / m < 3 > prepared by the invention has the 28d compressive strength of 13.68 MPa and the energy absorption value of 3.21 MJ / m < 3 >, has the characteristics of light weight, high strength, crack resistance and excellent energy absorption, and can show wide application prospects in the engineering fields of shock resistance, shock absorption, impact protection, energy dissipation and the like.

Description

Technical Field

[0001] This application relates to the field of protective materials for special engineering structures, specifically to a foamed concrete composed of ultrafine particle powder and fiber reinforcement, and its preparation method. Background Technology

[0002] Currently, the safety of tunnel structures has risen to an unprecedented strategic level in the field of protective engineering. Against this backdrop, lightweight porous solids have attracted widespread attention due to their lightweight porous structure, excellent large deformation under stress, and high energy absorption during crushing, and are increasingly being used in advanced designs such as vibration damping and blast protection. The working mechanism of these materials lies in the plastic yielding and layer-by-layer collapse of their internal honeycomb or foam-like microstructures, which transforms intense impact loads into a controllable and progressively released form of energy, thereby effectively dispersing and absorbing the enormous impact energy caused by instantaneous loads.

[0003] Foamed concrete, a novel lightweight porous solid material, also known as foamed concrete, foamed soil, lightweight soil, aerated concrete, or foamed cement, has attracted much attention due to its unique physical structure and excellent engineering performance. The preparation process of foamed concrete involves introducing a large number of uniform and stable micro-bubbles into cement paste or cement mortar, followed by thorough mixing, pouring and molding, and then curing to harden. Compared with other porous materials such as foamed metals, foamed polyurethane, and foamed ceramics, foamed concrete not only has significant advantages such as low cost, wide availability of raw materials, and simple preparation process, but also exhibits excellent fire resistance, good thermal and sound insulation effects, and excellent long-term stability, and is not prone to oxidation and corrosion. Furthermore, foamed concrete is highly adaptable to construction, unrestricted by site conditions and environmental factors, and can be flexibly poured and molded in confined spaces or complex geological conditions, ensuring efficient and stable engineering applications in diverse engineering scenarios.

[0004] Although foamed concrete has been widely used in various fields such as retaining walls, underground backfilling, environmental cover, and foundation engineering, current applications are mainly concentrated on products with relatively low performance. These materials generally suffer from prominent problems such as poor quality stability, low compressive strength, insufficient damping performance, and low energy absorption efficiency, making it difficult to meet the stringent requirements of special structural protection engineering in terms of safety, durability, and functionality. Therefore, there is an urgent need to develop a high-performance foamed concrete with high strength, excellent toughness, and good energy absorption capacity. Summary of the Invention

[0005] Existing foamed concrete still generally suffers from key problems such as low compressive strength, insufficient toughness, and poor energy absorption, which seriously restricts its practical application in structural protection engineering. To address this, this application provides a foamed concrete composite of ultrafine powder and fiber reinforcement, and its preparation method. This method produces high-performance foamed concrete with stable quality, high compressive strength, good crack resistance, high energy absorption, and good buffering effect. By designing and preparing lightweight, high-strength, and crack-resistant foamed concrete, the shock wave effect generated under extreme dynamic loads is significantly reduced.

[0006] To achieve the above objectives, this application adopts the following technical solution: In a first aspect, this application provides a foamed concrete composed of ultrafine particulate powder and fiber reinforcement, comprising, by weight: 220-320 parts of ultrafine particle composite powder, 0.5-7 parts of fiber reinforcement, 0.5-1.5 parts of water-reducing agent, 1-2 parts of calcium sulfoaluminate, 80-120 parts of water and a certain amount of foam; the weight percentage of the foam is determined by the design density of the foamed concrete.

[0007] As a further improvement of this application, the ultrafine particle composite powder includes ultrafine silicate cement SC and ultrafine slag SK; wherein, the average particle size of ultrafine silicate cement is <23μm, the average particle size of ultrafine slag SK is <5μm, and the SK content is ≤20% based on 100% of the total mass of the ultrafine particle composite powder.

[0008] As a further improvement of this application, mineral admixtures are also added to the ultrafine particle composite powder, including silica fume SF and fly ash FA; Among them, based on the total mass of the ultrafine particle composite powder as 100%, the content of silica fume (SF) is less than 1%, and the content of fly ash (FA) is less than 10%.

[0009] As a further improvement of this application, the fiber reinforcement includes one or more of polypropylene fiber, basalt fiber, polyvinyl alcohol fiber and steel-like fiber, and the fiber reinforcement content is <1.54%.

[0010] As a further improvement of this application, the fiber length in the fiber reinforcement is controlled at 6~12mm and the diameter at 10~20μm.

[0011] As a further improvement of this application, the water-reducing agent is a polycarboxylate superplasticizer mother liquor, the water reduction rate of the water-reducing agent is >30%, and the dosage of the water-reducing agent is <0.05%.

[0012] As a further improvement of this application, the foaming agent is an animal protein-based foaming agent, prepared by a physical foaming method, with the foam density controlled at 40~60 kg / m³. 3 between.

[0013] As a further improvement to this application, the weight percentage of the foam is determined by the design density of the foamed concrete, specifically by using the dry density method, and the calculation formula is as follows:

[0014]

[0015]

[0016] In the formula: ρ t The target dry density of the foamed concrete is defined by α; α is the mass coefficient of the cementitious material in the foamed concrete; M c M represents the required amount of cement. ma M represents the required amount of mineral admixtures. w ρ is the required amount of mixing water; β is the water-cement ratio used in the mix design; c ρ is the apparent density of cement. w β is the apparent density of water; M is the excess foam coefficient prepared by the foaming agent; f This refers to the amount of fresh foam used.

[0017] As a further improvement of this application, the foamed concrete has an apparent density of 849 kg / m³, a 28-day compressive strength of 13.68 MPa, and an energy absorption value of 3.21 MJ / m³.

[0018] Secondly, this application provides a preparation method for preparing the aforementioned ultrafine particle powder and fiber-reinforced composite foamed concrete, characterized in that it comprises: S1: Place the powder material weighed according to the foamed concrete mix proportion into a high-speed mixing bucket, then pour in the mixing water mixed with water-reducing agent, stir evenly, add fiber reinforcement, and stir until a cement paste is formed. S2: Calculate the amount of foam based on the dry density density method of foamed concrete, then dilute the foaming agent at a ratio of 20 to 30 times, control the foam density by adjusting the flow rate of the foaming water pump, and then start the foaming equipment to produce foam. S3: Pour the cement paste and weighed foam into the concrete mixer, mix and monitor the change in wet density of the foam concrete in real time until the target density is reached, then stop adding foam to obtain foam concrete composed of ultrafine powder and fiber reinforcement.

[0019] Compared to existing technologies, the advantages of this application are as follows: This application effectively solves the technical bottlenecks of traditional foamed concrete, such as insufficient strength, poor toughness, and low energy absorption efficiency, under the premise of lightweighting, by constructing a composite system of ultrafine powder gradation optimization, high-efficiency water reduction, fiber toughening, and foam stabilization control. It employs a blend of ultrafine silicate cement and ultrafine slag to achieve the densest particle packing, significantly reducing the proportion of harmful pores and improving matrix density and hydration. Polycarboxylate superplasticizers are used to improve rheological properties under high solids content, preventing ultrafine powder agglomeration and ensuring construction fluidity. Short-cut fibers are introduced to form a crack bridging mechanism, extending the stress plateau period during crushing and improving the energy absorption capacity per unit volume. Animal protein-based foaming agents are used to generate micro-foams with high closed-cell ratio and stable pressure resistance, ensuring uniform pore structure and resistance to fusion and breakage. By combining dry density methods with real-time monitoring of wet density, a closed-loop management system is achieved from formulation design to molding control, resulting in good batch-to-batch consistency. The final product is a high-performance foamed concrete with an apparent density of 849 kg / m³, a 28-day compressive strength of 13.68 MPa, and an energy absorption value of 3.21 MJ / m³, exhibiting superior overall performance compared to existing similar products. This material is suitable for tunnel lining, underground backfilling, seismic buffer layers in buildings, and impact protection projects, demonstrating promising application prospects. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort, wherein: Figure 1 XRD pattern of ultrafine slag modified foamed concrete; Figure 2 SEM images of ultrafine slag modified foamed concrete are shown below. (a1) 0% SK, (b1) 10% SK, (c1) 20% SK, (d1) 40% SK represent the overall pore size; (a2) 0% SK, (b2) 0% SK, (c2) 20% SK, (d2) 40% SK represent the pore wall structure size; (a3) ​​0% SK, (b3) 10% SK, (c3) 20% SK, (d3) 40% SK represent the fine pore size size. Figure 3 For the compression test process of ultrafine fiber reinforced foam concrete; Figure 4 Energy absorption curve of ultrafine fiber reinforced foam concrete; Figure 5 This is a literature review on the relationship between the compressive strength and density of foamed concrete. Detailed Implementation

[0021] To make the technical problems, technical solutions, and beneficial effects of this application clearer, the following detailed description is provided in conjunction with embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application.

[0022] In this application, the term "and / or" describes the relationship between related objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone. A and B can be singular or plural. The character " / " generally indicates that the preceding and following related objects have an "or" relationship.

[0023] In this application, "at least one" means one or more, and "more than one" means two or more. "At least one of the following" or similar expressions refer to any combination of these items, including any combination of single or multiple items. For example, "at least one of a, b, or c", or "at least one of a, b, and c", can both mean: a, b, c, a~b (i.e., a and b), a~c, b~c, or a~b~c, where a, b, and c can be single or multiple.

[0024] It should be understood that in the various embodiments of this application, the order of the above processes does not imply the order of execution. Some or all steps may be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of this application.

[0025] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application. The singular forms “a,” “the,” and “the” used in the embodiments of this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise.

[0026] The weights of the relevant components mentioned in the embodiments of this application can refer not only to the specific content of each component, but also to the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components is scaled up or down proportionally according to the embodiments of this application, it is within the scope disclosed in the embodiments of this application. Specifically, the mass in the embodiments of this application can be a mass unit known in the chemical industry, such as µg, mg, g, or kg.

[0027] The terms "first" and "second" are used for descriptive purposes only, to distinguish objects, such as substances, from one another, and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. For example, without departing from the scope of the embodiments of this application, "first XX" may also be referred to as "second XX," and similarly, "second XX" may also be referred to as "first XX." Thus, features defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0028] The following implementation examples further illustrate the technical solution of this application and fully demonstrate the innovation and practicality of this application. However, it should be noted that these examples are for illustration only and not for limitation, and do not constitute a limitation on the scope of protection of this application.

[0029] The first objective of this application is to provide a foamed concrete composed of ultrafine particle powder and fiber reinforcement. The raw material mix of the foamed concrete contains the following components: ultrafine particle composite powder, fiber reinforcement, water-reducing agent, calcium sulfoaluminate, water, and a certain amount of foam.

[0030] In the foamed concrete raw material mix proportion, by weight, the ultrafine particle composite powder accounts for 220-320 parts, the fiber reinforcement accounts for 0.5-7 parts, the water-reducing agent accounts for 0.5-1.5 parts, the calcium sulfoaluminate accounts for 1-2 parts, the water accounts for 80-120 parts, and the weight proportion of foam is determined by the design density of the foamed concrete.

[0031] By introducing ultrafine slag SK to regulate the particle size distribution of the composite powder, the densest packing state of the composite powder is achieved, effectively reducing the specific surface area of ​​the composite powder and significantly improving the density and pore distribution characteristics of the foamed concrete matrix. Simultaneously, the average particle size of the designed composite powder is much smaller than that of ordinary Portland cement, which not only fully promotes the hydration reaction and increases the generation of CSH gel products, but also increases the number of harmless pores and reduces the proportion of harmful pores, thereby enhancing the mechanical properties of the foamed concrete. Furthermore, by utilizing inert microparticles, water-reducing agents, fiber reinforcements, and high-strength foam, the rheological properties of the foamed cement paste are synergistically regulated, solving the problems of easy agglomeration and dispersion of ultrafine powders and the difficulty in foam incorporation. This results in a product that combines lightweight, high strength, crack resistance, and excellent energy absorption characteristics, demonstrating broad application prospects in engineering fields such as earthquake resistance, shock protection, and energy dissipation.

[0032] To effectively address the aforementioned problems in the practical application of foamed concrete, this application, focusing on strengthening the foam matrix and reducing harmful porosity, abandons the conventionally used PO42.5 and PO52.5 grade ordinary Portland cement as the cementing material, and instead selects ultrafine particle cement with a finer particle size. Ultrafine particle cement not only has finer particles and a significantly increased specific surface area, but also possesses higher cured strength and better early strength development capability, achieving good structural stability without the need for additional nanomaterials. However, the extremely high specific surface area of ​​the ultrafine composite powder also brings a series of key technical challenges, such as a significant increase in water demand, a significant increase in slurry viscosity, and difficulties in foam incorporation as the powder fineness decreases.

[0033] The ultrafine particle composite powder consists of ultrafine silicate cement (SC) and ultrafine slag (SK), wherein the average particle size of the ultrafine silicate cement is <23μm, the average particle size of the ultrafine slag (SK) is <5μm, and the SK content is ≤20%. When the SK content is >20%, the interaction force between the ultrafine particles will be significantly reduced, resulting in powder sedimentation and separation. Based on 100% of the total mass of the ultrafine particle composite powder, it is recommended that the weight ratio of SK be controlled at around 10%.

[0034] Optionally, a small amount of mineral admixtures may be added to the ultrafine particle composite powder, with silica fume (SF) content <1% and fly ash (FA) content <10%. When the SF and FA content exceed the specified values, the foam slurry will exhibit thickening and sedimentation phenomena, respectively.

[0035] By employing an ultrafine composite powder system composed of ultrafine cement and ultrafine slag, the particle size of the composite powder was significantly reduced, achieving the most compact packing design of particle size distribution. This system not only effectively reduces the specific surface area of ​​the composite powder, promotes the degree of hydration reaction, and increases the amount of CSH gel products generated, but also increases the number of harmless pores and reduces the proportion of harmful pores, thereby improving the density and porosity distribution characteristics of the foamed concrete matrix.

[0036] Optionally, the average particle size of the ultrafine slag SK is less than 5 μm, and the dosage does not exceed 20 wt% of the total mass of the composite powder, preferably 10-15 wt%. As a micro-filler, ultrafine slag has a particle size much smaller than traditional cement particles (typically 45-60 μm), effectively embedding itself between ultrafine silicate cement particles to achieve the densest packing. Experiments show that when the SK dosage exceeds 20 wt%, the system viscosity decreases, the interparticle forces weaken, and sedimentation and segregation occur; controlling it within the 10-15 wt% range significantly improves the matrix density without compromising the slurry stability. This dosage range has been verified by multiple tests, and the compressive strength consistently reaches above 13.68 MPa at a bulk density of 849 kg / m³. In practical applications, slag can be replaced with mineral admixtures such as nano-silica or metakaolin.

[0037] By introducing ultrafine slag to optimize the gradation of ultrafine microparticle composite powder, the densest packing between particles is achieved, reducing the overall specific surface area. Based on Andreasen's particle packing theory, different particle sizes (SC and SK) are rationally combined to maximize particle packing density and minimize porosity. This structure reduces water demand per unit volume, inhibits capillary development, increases CSH gel formation, and enhances matrix continuity. SEM images show a more uniform pore distribution, with the proportion of harmful pores (>50nm) reduced to below 15%. In practical applications, the gradation curve can be dynamically adjusted using laser particle size analysis.

[0038] To address the technical challenges posed by the reduced fineness of ultrafine composite powders as the matrix of foamed concrete, such as a significant increase in water demand, a sharp increase in slurry viscosity, and difficulties in foam incorporation, this application addresses these issues. Firstly, it incorporates ultrafine slag into the composite powder design to effectively disperse ultrafine cement particles and improve the system's rheological properties. Secondly, it utilizes the strong steric hindrance effect of high-performance water-reducing agents to suppress cement particle agglomeration.

[0039] Optionally, the high-performance water-reducing agent is a polycarboxylate superplasticizer mother liquor with a water reduction rate >30% and a dosage <0.05%. When the dosage of polycarboxylate superplasticizer mother liquor exceeds 0.05%, the stability of the foamed cement paste decreases, and ultrafine powder sedimentation and separation occur. A dosage of 0.35% is recommended. The synergistic effect of the high-performance water-reducing mother liquor and the special mixing and preparation process effectively controls the rheological properties and viscosity of the cement paste, solving the problems of easy agglomeration and difficult mixing of ultrafine powder.

[0040] Optionally, the water-reducing agent is a polycarboxylate-based high-performance water-reducing mother liquor with a water reduction rate greater than 30%, and the dosage is controlled between 0.5‰ and 1.5‰ of the total cementitious material. The polycarboxylate water-reducing agent has a comb-like molecular structure, providing strong steric hindrance and electrostatic repulsion, effectively dispersing ultrafine powder particles with high specific surface areas and preventing agglomeration. The recommended dosage is 0.35‰, and the measured flow spread reaches over 260 mm, meeting the construction fluidity requirements for foam incorporation. This water-reducing agent maintains good dispersion performance even under low water-cement ratio conditions. In practical applications, commercial products such as Sika ViscoCrete-30 and Kezhijie Point-402 can be selected.

[0041] When the dosage of polycarboxylate superplasticizer exceeds 0.05% of the total cementitious material, the stability of the foamed concrete slurry decreases, leading to powder settling and foam rupture. Although superplasticizers can improve rheological properties, excessive addition can entrain excessive air, damaging the integrity of the foam structure and causing bubbles to merge and float. Orthogonal experiments determined the optimal dosage window to be 0.35‰~0.5‰, within which the slurry viscosity is moderate and the foam retention capacity is strongest. If the dosage is too high, the wet density fluctuates greatly, affecting the final molding quality. In practical applications, the dispersion state can be determined by Zeta potential detection.

[0042] To effectively reduce the brittle fragment collapse phenomenon generated during the crushing and energy absorption process of foamed concrete and improve its energy absorption efficiency, fiber reinforcement is added to improve the crack resistance and toughness of foamed concrete, thereby extending the energy absorption stress plateau of the specimen and achieving more uniform and continuous energy dissipation.

[0043] Optionally, the calcium sulfoaluminate is a light yellow powder that promotes the hydration reaction process, shortens the induction period of hydration products such as CSH, and enhances the nucleation ability of CSH gel products.

[0044] The fiber reinforcement includes, but is not limited to, polypropylene fibers, basalt fibers, polyvinyl alcohol fibers, and steel-like fibers, with a fiber reinforcement content of <1.54%. Polypropylene fibers are recommended, with a fiber content of 0.47%. The fiber reinforcement includes one or more combinations of polypropylene fibers, basalt fibers, polyvinyl alcohol (PVA) fibers, and steel-like fibers. The various fibers complement each other: polypropylene fibers are low-cost and highly alkali-resistant, suitable for large-scale use; glass fiber / basalt fibers have high modulus, improving impact resistance; PVA fibers have good hydrophilicity and a strong bond with the cement interface; steel-like fibers provide a metal-like toughening mechanism, suitable for high-protection areas. All fibers are controlled to a length of 6-12 mm and a diameter of 10-20 μm to balance bridging effect and mixing difficulty. In practical applications, hybrid fiber designs can also be used.

[0045] The fiber reinforcement content is 0.5–7 parts (corresponding to a volume fraction of 0.5%–1.54%), used to achieve an optimal balance between crack suppression and energy absorption capacity. Insufficient fiber content will result in ineffective crack bridging and a short energy absorption plateau; excessive content will cause the fibers to entangle and create local weak points. Experiments show that when the polypropylene fiber content is 0.47‰, the 28-day compressive strength reaches 13.68 MPa, and the energy absorption value is the highest (3.21 MJ / m³). This content balances mechanical properties and economy. In practical applications, gradient content can be set according to the stress requirements, such as using a low content for buffer layers and a high content for critical load-bearing areas.

[0046] To address the challenges of incorporating foam into high-viscosity cement paste and its tendency to deform under pressure, a high-performance foam with good stability and high load-bearing capacity was designed, effectively improving the compatibility between foam and cement paste.

[0047] The high-performance foam with good stability and high load-bearing capacity is prepared by physical foaming, using an animal protein-based foaming agent, and the foam density is controlled at 40~60 kg / m³. 3 The amount of foam used depends on the design density of the foamed concrete, i.e., the mix proportion of the foamed concrete.

[0048] The mix proportion of foamed concrete is designed using the dry density method, and the calculation formulas are shown in (1~3).

[0049]

[0050]

[0051]

[0052] In the formula: ρ t To design the target dry density (kg / m³) of foamed concrete 3 ); α is the mass coefficient of the cementitious material in foamed concrete; M c The required amount of cement (kg); M ma The required amount of mineral admixture (kg); M w ρ is the required mixing water quantity (kg); β is the water-cement ratio used in the mix design; c The apparent density of cement is taken as 3150 kg / m³. 3 ;ρ w The apparent density of water is taken as 1000 kg / m³. 3 β is the excess foam coefficient prepared by the foaming agent, which is related to the stability of the foam, and is usually taken as 1.1~1.5; M f This represents the amount of fresh foam used (kg). The formula is based on the principle of volume conservation, taking into account foam compression, transportation losses, and construction fluctuations. The amount of foam used is calculated by reverse-engineering the dry density method, achieving design-to-formulation. For example, when the target bulk density is 849 kg / m³, This ensures sufficient foam. In practical applications, adjustments can be made based on on-site testing. Value. By comparing the compatibility of different foaming agents with high-viscosity, low-water-cement-ratio cement paste, foams with good stability, high load-bearing capacity, and small deformation under pressure are selected to ensure that the foams are not easily broken or fused in high-viscosity conditions.

[0053] Adding calcium sulfoaluminate as an early strength activating component promotes the CSH gel nucleation rate, shortens the hydration induction period, and accelerates early strength development. Calcium sulfoaluminate rapidly forms the ettringite (AFt) phase during the initial hydration stage, releasing a large amount of Ca²⁺. + and Al³ + Ions accelerate the hydration reaction. Early strength development is particularly crucial for low-density foamed concrete, preventing collapse and delamination caused by foam rising to the surface. The recommended addition amount is 1-2 parts, approximately 0.5%-1.0% of the cementitious material, allowing for initial setting within 3 hours and demolding within 6 hours. In practical applications, early strength can be further optimized by combining it with a temperature-controlled curing regime.

[0054] The foaming agent is animal protein-based and prepared using a physical foaming method. The resulting foam exhibits high closed-cell rate, good elasticity, and strong compressive stability. Made from natural keratin extract, the animal protein foaming agent has high surface tension and thick foam walls, producing foam with a closed-cell rate ≥85% and strong resistance to compressive deformation. It maintains structural integrity even in high-viscosity cement paste, resisting collapse or fusion. Compared to synthetic foaming agents, its foam stabilization time is extended by more than 40%. In practical applications, modified plant protein or composite foaming agents can also be used.

[0055] The foam density is controlled between 40 and 60 kg / m³, precisely adjusted by regulating the foaming agent dilution ratio (20-30 times) and water pump flow rate. Foam density directly affects the finished product's dry density and mechanical properties. 40 kg / m³ foam is light but brittle, while 60 kg / m³ foam has strong load-bearing capacity but sacrifices lightweight advantages. By controlling the dilution ratio and air pressure, the target density can be output with an accuracy of ±2 kg / m³. The foaming equipment features a feedback closed loop and supports automatic compensation. In practical applications, the foam density can be configured in stages according to project requirements.

[0056] In the preparation process, the powder is first stirred at high speed with water containing a water-reducing agent for at least 3 minutes, and then the fiber reinforcement is added for dispersion and mixing. This order of addition ensures that the powder is fully wetted and dispersed, preventing the fibers from clumping in the undispersed slurry. The three-stage mixing process is as follows: dry powder premixing, water + water-reducing agent mixing, fiber addition → slow mixing, foam introduction → low-speed mixing. This process ensures the orderly integration of each component. In practical applications, the mixing time can be automatically determined based on the consistency.

[0057] Secondly, this application also provides a method for preparing crack-resistant and toughened foamed concrete, specifically including the following steps: S1: Weigh the powder material according to the foamed concrete mix proportion and put it into the high-speed mixing bucket. Then pour in the mixing water mixed with water-reducing agent and stir for more than 3 minutes. Finally, add the fiber reinforcement and stir until a cement paste with good rheological properties is formed.

[0058] S2: Calculate the amount of foam to be used based on the dry density and bulk density method of foamed concrete, then dilute the foaming agent at a ratio of 20 to 30 times, control the foam density by adjusting the flow rate of the foaming water pump, and finally start the foaming equipment to produce foam.

[0059] S3: Pour the above slurry and weighed foam into the concrete mixer and mix for no less than 3 minutes. Monitor the change in wet density of the foamed concrete in real time until the target density is reached. Then, stop adding foam and pour the foamed cement slurry into the concrete mold. After standard curing for 28 days, test the various performance indicators of the foamed concrete.

[0060] The order of adding materials S1, S2 and S3 is controlled at a speed between 500 r / min and 3000 r / min during high-speed mixing. The density of foamed concrete is controlled by the dry density method, combined with dynamic auxiliary adjustment of wet density, so as to achieve the final design target density.

[0061] The particle size distribution of ultrafine slag SK-controlled composite powder is effectively reduced, significantly improving the density and pore distribution characteristics of foamed concrete matrix. Simultaneously, the designed method not only fully enhances the mechanical properties of foamed concrete, but also innovatively utilizes inert microparticles, water-reducing agents, fiber reinforcements, and high-strength foam to synergistically regulate the rheological properties of foamed cement paste, solving technical challenges such as the easy agglomeration and dispersion difficulties of ultrafine powders and the difficulty in foam incorporation. Furthermore, the polycarboxylate superplasticizer mother liquor for foamed concrete prepared in this application, combined with ultrafine slag for multi-component composite optimization, precisely controls the material mix ratio, and employs advanced mixing technology to achieve stable foam introduction and three-dimensional uniform distribution in a high-viscosity system. This significantly improves the mechanical properties and energy retardation absorption performance: the apparent density is 849 kg / m³. 3 The high-performance fiber-reinforced foam concrete has a 28-day compressive strength of 13.68 MPa and an energy absorption value of 3.67 MJ / m³. 3 .

[0062] The speed of the S1 high-speed mixing tank is controlled between 500 and 3000 r / min to achieve efficient shearing and dispersion and prevent powder agglomeration. Low speeds are insufficient to break down the van der Waals forces between ultrafine particles, leading to localized enrichment; while high speeds enhance shearing, they may introduce air bubbles or damage fibers. The preferred speed is 1500–2000 r / min, combined with anchor-type impellers, resulting in high shearing efficiency and low energy consumption. In practical applications, a variable frequency speed control system can be used to dynamically adjust the speed according to the slurry viscosity.

[0063] The wet density of the foamed concrete is monitored in real time during the foam incorporation process. As the density approaches the target level, the foam input is gradually reduced to achieve dynamic control. Wet density monitoring uses a vibrating wire density sensor or a gamma-ray density meter, collecting data every 10 seconds. When the measured density reaches 95% of the target value, a fine-tuning foaming stage begins, reducing the flow rate by 50%; foaming is stopped once the target is reached. This mechanism prevents over-foaming from causing excessive density and ensures batch consistency. In practical applications, the wet density signal can be connected to a PLC control system for automatic adjustment.

[0064] The resulting foamed concrete has an apparent density of 849 kg / m³, meeting the dual requirements of lightweight construction and structural load-bearing capacity. This density conforms to the definition of lightweight concrete in JG / T 266~2011 standard, and it also possesses a compressive strength of 13.68 MPa, significantly higher than ordinary foamed concrete of the same density (typically 7~9 MPa). It is suitable for applications such as underground backfilling, seismic diaphragms, and tunnel linings, where self-weight is sensitive but a certain strength is required. In practical applications, a gradient design within the range of 700~1000 kg / m³ can be achieved by adjusting the foam density.

[0065] Furthermore, the 28-day compressive strength is no less than 13.68 MPa, and the energy absorption value is no less than 3.21 MJ / m³, demonstrating excellent energy dissipation capabilities. The energy absorption value is obtained by integrating the stress-strain curve, reflecting the material's energy absorption capacity during the crushing process. At a density of 849 kg / m³, the energy absorption value of conventional foamed concrete is only around 2.5 MJ / m³, while this application achieves an energy absorption increase of over 47% due to the synergistic effect of a dense matrix and fiber toughening. These performance indicators have been verified through drop hammer impact tests and static compression tests. In practical applications, its performance under dynamic loads can be predicted using numerical simulations.

[0066] Based on the above analysis, the foamed concrete is used for tunnel lining, backfilling of underground structures, seismic buffer layers in buildings, or impact protection barriers for military facilities. In tunnel engineering, it is used for backfilling non-load-bearing sections, serving both support and vibration reduction functions; in high-rise buildings, it acts as a floor-level seismic isolator, extending the vibration period; in military bunkers, it is used as the core material of blast-resistant walls, effectively attenuating shock waves. Due to its lightweight and high energy absorption characteristics, it is particularly suitable for engineering scenarios with inconvenient transportation and limited hoisting capabilities. In practical applications, it can be prefabricated into slabs or blocks or cast in place.

[0067] This application also provides a foamed concrete preparation apparatus for a method of preparing foamed concrete composed of ultrafine powder and fiber reinforcement, including a high-speed mixing unit, a foaming unit, a metering and conveying unit, and a casting mold.

[0068] High-speed mixing unit: Equipped with a variable frequency motor and sealing cover, supporting stepless speed regulation from 500 to 3000 r / min; Foaming unit: An independently operating physical foaming machine, integrating a flow valve and density feedback module; Metering and conveying unit: Electronic weighing linkage control, error ≤0.5%, ensuring proportioning accuracy; The pouring gate of the casting mold is equipped with a guide groove to prevent slurry segregation.

[0069] This device boasts a high degree of integration, making it suitable for mobile pumping operations. In practical applications, each unit can be disassembled into a modular device, facilitating transportation and installation.

[0070] The following is a detailed description of the contents of this application based on specific embodiments: Example 1: A method for preparing foamed concrete composed of ultrafine powder and fiber reinforcement, comprising the following steps: (1) The raw material mix proportion of foamed concrete includes 220-320 parts of ultrafine particle composite powder, 0.5-7 parts of fiber reinforcement, 0.5-1.5 parts of water-reducing agent, 1-2 parts of calcium sulfoaluminate, 80-120 parts of water, and a certain amount of foam. The preparation method of foamed concrete is as follows: S1: Place the weighed powder of foamed concrete into a high-speed mixing bucket, then pour in the mixing water mixed with water-reducing agent, stir for more than 3 minutes, and finally add fiber reinforcement and stir until a cement paste with fine texture and good rheological properties is formed.

[0071] S2: Based on the dry density and bulk density design method of foamed concrete, the foaming agent is diluted at a ratio of 20 to 30 times. The foam density is controlled by adjusting the flow rate of the foaming water pump. Then, the foaming equipment is started to produce uniform, delicate and stable foam.

[0072] S3: Pour the above slurry and weighed foam into a concrete mixer and mix for more than 3 minutes. Monitor the change in wet density of the foamed concrete until the target density is reached. Then, stop adding foam and pour the foamed cement slurry into the mold. After standard curing for 28 days, test the various performance indicators of the foamed concrete.

[0073] Example 2: A method for preparing foamed concrete composed of ultrafine particle powder and fiber reinforcement, comprising the following steps: (1) The raw material mix proportion of foamed concrete includes 220-320 parts of ultrafine particle composite powder, 0.5-7 parts of fiber reinforcement, 0.5-1.5 parts of water-reducing agent, 1-2 parts of calcium sulfoaluminate, 80-120 parts of water, and a certain amount of foam. The preparation method of foamed concrete is as follows: S1: Place the weighed powder of foamed concrete into a high-speed mixing bucket, then pour in the mixing water mixed with water-reducing agent, stir for more than 3 minutes, and finally add fiber reinforcement and stir until a cement paste with fine texture and good rheological properties is formed.

[0074] S2: Based on the dry density and bulk density design method of foamed concrete, the foaming agent is diluted at a ratio of 20 to 30 times. The foam density is controlled by adjusting the flow rate of the foaming water pump. Then, the foaming equipment is started to produce uniform, delicate and stable foam.

[0075] S3: Pour the above slurry and weighed foam into a concrete mixer and mix for more than 3 minutes. Monitor the change in wet density of the foamed concrete until the target density is reached. Then, stop adding foam and pour the foamed cement slurry into the mold. After standard curing for 28 days, test the various performance indicators of the foamed concrete.

[0076] Example 3: A method for preparing foamed concrete composed of ultrafine powder and fiber reinforcement, comprising the following steps: (1) The raw material mix proportion of foamed concrete includes 220-320 parts of ultrafine particle composite powder, 0.5-7 parts of fiber reinforcement, 0.5-1.5 parts of water-reducing agent, 1-2 parts of calcium sulfoaluminate, 80-120 parts of water, and a certain amount of foam. The preparation method of foamed concrete is as follows: S1: Place the weighed powder of foamed concrete into a high-speed mixing bucket, then pour in the mixing water mixed with water-reducing agent, stir for more than 3 minutes, and finally add fiber reinforcement and stir until a cement paste with fine texture and good rheological properties is formed.

[0077] S2: Based on the dry density and bulk density design method of foamed concrete, the foaming agent is diluted at a ratio of 20 to 30 times. The foam density is controlled by adjusting the flow rate of the foaming water pump. Then, the foaming equipment is started to produce uniform, delicate and stable foam.

[0078] S3: Pour the above slurry and weighed foam into a concrete mixer and mix for more than 3 minutes. Monitor the change in wet density of the foamed concrete until the target density is reached. Then, stop adding foam and pour the foamed cement slurry into the mold. After standard curing for 28 days, test the various performance indicators of the foamed concrete.

[0079] Example 4: A foamed concrete composed of ultrafine powder and fiber reinforcement, and its preparation method, comprising the following steps: (1) 220~320 parts of ultrafine particle composite powder, 0.5~7 parts of fiber reinforcement, 0.5~1.5 parts of water-reducing agent, 1~2 parts of calcium sulfoaluminate, 80~120 parts of water and some foam. 90 parts of ultrafine particle composite powder, ultrafine silicate cement, and 10 parts of ultrafine slag.

[0080] The preparation method of foamed concrete is as follows: S1: Place the weighed powder of foamed concrete into a high-speed mixing bucket, then pour in the mixing water mixed with water-reducing agent, stir for more than 3 minutes, and finally add fiber reinforcement and stir until a cement paste with fine texture and good rheological properties is formed.

[0081] S2: Based on the dry density and bulk density design method for foamed concrete, the foaming agent is diluted at a ratio of 25:1. The foam density is controlled by adjusting the flow rate of the foaming water pump, with a set foam density of 45 kg / m³. Then, the foaming equipment is started to produce uniform, fine, and stable foam.

[0082] S3: Pour the above slurry and weighed foam into a concrete mixer and mix for more than 3 minutes. Monitor the change in wet density of the foamed concrete until the target density is reached. Then, stop adding foam and pour the foamed cement slurry into the mold. After standard curing for 28 days, test the various performance indicators of the foamed concrete.

[0083] The specific process for testing the performance of foamed concrete is as follows: Case Study 1 The prepared foamed cement slurry was poured into a 100mm×100mm×100mm mold. After molding for 24 hours, the molded sample was demolded and placed in a standard curing chamber at (20±2)℃ and relative humidity >95% for 28 days. The phase composition of the foamed concrete was analyzed using X-ray diffraction. Figure 1 As shown, the hydration products of ultrafine composite powder foamed concrete mainly include C-(A)-SH gel, Ca(OH)2, hydrotalcite, hydrotalcite-like substances, and unhydrated C2S / C3S. The microstructure of the foamed concrete was analyzed using scanning electron microscopy (SEM).

[0084] Specifically, Figure 1 The X-ray diffraction (XRD) spectra of foamed concrete with different amounts of ultrafine composite powder (SCSK0, SCSK10, SCSK20, SCSK30) reflect the variation of hydration products and unhydrated minerals: 1. Diffraction Peak Characteristics and Corresponding Changes of Each Phase: Portlandite (Ca(OH)2, calcium hydroxide): Characteristic peaks around 2θ≈18°. The peak intensity is highest in SCSK0 (green curve). With increasing ultrafine composite powder content (SCSK10→SCSK20→SCSK30), the peak intensity continuously decreases—indicating that Ca(OH)2 is consumed by the pozzolanic reaction of the ultrafine composite powder, and its content gradually decreases. Hydrotalcite and Hydrotalcite-like phases: Characteristic peaks around 2θ≈30° and 40°, respectively. With increasing content, the intensity of these peaks gradually increases (especially the blue curve of SCSK30); indicating that the formation of hydrotalcite and hydrotalcite-like hydration products increases with increasing content. Unhydrated C2S / C3S (cement minerals): Characteristic peaks around 2θ≈30° and 40° (partially overlapping with hydrotalcite peaks). From SCSK0 to SCSK30, the relative intensities of these peaks gradually decrease, indicating that more unhydrated cement minerals participated in the hydration / volcanic ash reaction, and the reaction was more complete. C-(A)-SH gel: Since C-(A)-SH is an amorphous substance, there are no obvious characteristic diffraction peaks in XRD, but its formation can be indirectly inferred by the decrease of Ca(OH)2 and the increase of hydration products (corresponding to the gel coverage phenomenon observed in SEM).

[0085] With the increase of ultrafine composite powder content: the amount of unhydrated cement minerals (C2S / C3S) decreases, the volcanic ash reaction consumes Ca(OH)2, and the amount of hydration products such as hydrotalcite and hydrotalcite-like substances increases, and the degree of hydration reaction gradually increases.

[0086] like Figure 2 As shown, the pore surface of the foamed concrete modified with ultrafine slag changed from smooth micropores to C-(A)-SH gel-covered and filled, while the porosity of the pore walls was significantly reduced, resulting in a denser structure. Then, the dry density (kg / m³) of the foamed concrete was measured according to the method in the standard JG / T266-2011 Foamed Concrete. 3 The compressive strength (MPa) at 28 days and the energy absorption properties were measured.

[0087] Specifically, Figure 2 This paper presents the SEM microstructure of foamed concrete (SCFC) with different ultrafine slag (SK) admixtures. Using four groups of samples (0%, 10%, 20%, and 30% SK) and three magnification dimensions for each group (overall pore structure, pore wall structure, and fine pores), the changes in the modified microstructure are revealed. 1. Baseline group (Group a: 0%SK): Loose structure with obvious defects; (a1): Pore surface is relatively smooth, but there are obvious cracks, and the structural integrity is poor; (a2): Loose microstructure, no significant gel-like substances, and disordered pore distribution; (a3): Loose structure, large pores, accompanied by cracks, and low overall density.

[0088] 2.10%SK group (b group): Initial gel formation, the structure begins to become dense; (b1): Gel-like substances adhere to the surface of the pores (no longer completely smooth), but cracks still exist; (b2): A plate-like C-(A)-SH gel structure appears, which begins to fill the pores, but the gel distribution is relatively loose; (b3): ​​The pores are smaller than those of the baseline group, the structure tends to be dense, but cracks still exist.

[0089] 3.20%SK group (c group): dense gel and significantly reduced pore size; (c1): the surface of the pores is completely covered by a large amount of gel, and the surface is roughened; (c2): the C-(A)-SH gel structure is more developed and dense, fully filling the pores of the pore walls; (c3): the pores are further reduced, the structural compactness is greatly improved, and the number / width of cracks is reduced.

[0090] 4.30%SK group (d group): Dense structure with sufficient gel coating; (d1): The surface of the pores is almost completely covered by the gel, and the texture is richer; (d2): The gel forms a continuous and dense sheet-like / floc-like structure, and the filling effect is more thorough; (d3): The pores are significantly reduced, the structure is highly dense, and the probability of cracks is further reduced.

[0091] With the increase of ultrafine slag (SK) content, the microstructure of foamed concrete shows a transformation from smooth with little gel to dense gel coverage, and from loose and porous to dense filling. The amount of C-(A)-SH gel generated increases with the increase of SK content, continuously filling the pore walls and pores, making the structure denser and improving crack defects to a certain extent.

[0092] The testing process and test curves for the energy absorption performance of ultrafine fiber reinforced foamed concrete are as follows: Figure 3 and 4 As shown, the relationship between loading force and displacement is obtained through a quasi-static mechanical compression test.

[0093] Figure 4This is a correlation curve of stress-strain, energy absorption, and energy absorption efficiency under quasi-static compression test. The horizontal axis represents strain, the left vertical axis represents compressive strength, and the right double vertical axes correspond to energy absorption efficiency and energy absorption value, respectively. It primarily reflects the mechanical behavior and energy dissipation characteristics of the material during compression. This curve embodies the compressive mechanical properties of ultrafine fiber reinforced foamed concrete. 1. Stress-strain curve (black): Three-stage mechanical behavior, divided into three stages: Initial elastic stage (strain < 0.1): Compressive strength rapidly rises to its peak value (13.68 MPa), indicating that the material has high stiffness under small deformation and the internal pores have not yet been extensively damaged. Energy absorption plateau stage (strain 0.1~0.6): After the strength decreases, it enters a gentle fluctuation zone, which is a typical pore compression / damage section of foamed concrete; the internal pores gradually collapse, and the interface slips between the fiber and the matrix, which is the main energy dissipation stage. Dense reinforcement stage (strain > 0.6): The strength rises again, due to the bridging / reinforcement effect of ultrafine particles and fibers after pore compression and densification, improving the material's later load-bearing capacity. 2. Energy Absorption Curve (Red): Cumulative energy dissipation; energy absorption is the area enclosed by the stress-strain curve and the strain axis. Therefore, the curve rises continuously with increasing strain, eventually reaching 3.21 MJ / m³. This indicates that the material can effectively accumulate and absorb energy under quasi-static compression, making it suitable as a buffer and impact-resistant component. 3. Energy Absorption Efficiency Curve (Blue): High-efficiency energy absorption range; energy absorption efficiency reflects the effectiveness of energy absorption. The curve first rises and then tends to stabilize: at strain ≈ 0.35927, the energy absorption efficiency reaches 35.75%. This strain range is the high-efficiency energy absorption segment of the material: it ensures sufficient deformation while efficiently converting external force into internal energy from internal pore failure and interface slippage. Therefore, it can be concluded that the modification with ultrafine particles and fibers allows foamed concrete to simultaneously possess high initial stiffness, a stable energy absorption plateau, and later-stage compaction reinforcement, exhibiting good cumulative energy absorption value and energy absorption efficiency, thus balancing load-bearing capacity and energy dissipation capacity.

[0094] The compressive stress value was obtained through calculation and data processing. (unit: MPa) and compressive strain value The compressive stress-strain curve (%), where the compressive stress value σ is the ratio of the actual compressive force F applied to the specimen during the compression test to its original cross-sectional area S, and the compressive strain value... The quasi-static stress-strain curve is obtained by taking the percentage ratio of the deformation ΔL of the original gauge length segment after the specimen is subjected to force to the original gauge length L of the specimen. Then, the absorbed energy value w (in MJ / m) is calculated according to the following formulas (1) and (2). 3 ).

[0095]

[0096]

[0097] The specific test results are shown in Table 1.

[0098] Table 1

[0099] Figure 5 This is a literature review on the relationship between compressive strength and density in foamed concrete. The review article was published in the journal Open Ceramics. The article is titled Compaore A, Toure JYNK, Klenam DEP, et al. Foamconte with mineral additives: from microstructure to mechanical / physical properties, workability and durability[J]. Open Ceramics, 2025, 23(000).DOI:10.1016 / j.oceram.2025.100812. Figure 5 As can be seen from the data, the compressive strength of the composite foamed concrete using ultrafine microfiber is 13.68 MPa, which is much higher than the compressive strength of foamed concrete in the latest review.

[0100] The above description is merely an exemplary illustration of preferred embodiments of this application, intended to provide a reference path for technical implementation, and not to limit the scope of protection of this application. As is well known to those skilled in the art, the essence of technological innovation lies in continuous evolution and optimization. Therefore, even without departing from the core concept and basic architecture of this application, adaptive adjustments or equivalent replacements to process parameters, structural layout, material selection, or functional modules in specific implementation schemes all fall within the technical scope covered by this application.

Claims

1. A foamed concrete composed of ultrafine powder and fiber reinforcement, characterized in that, By weight, it includes: 220-320 parts of ultrafine particle composite powder, 0.5-7 parts of fiber reinforcement, 0.5-1.5 parts of water-reducing agent, 1-2 parts of calcium sulfoaluminate, 80-120 parts of water and a certain amount of foam; the weight percentage of the foam is determined by the design density of the foamed concrete.

2. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The ultrafine particle composite powder includes ultrafine silicate cement SC and ultrafine slag SK; wherein, the average particle size of ultrafine silicate cement is <23μm, the average particle size of ultrafine slag SK is <5μm, and the SK content is ≤20% based on 100% of the total mass of the ultrafine particle composite powder.

3. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The ultrafine particle composite powder also contains mineral admixtures, including silica fume SF and fly ash FA. Among them, based on the total mass of the ultrafine particle composite powder as 100%, the content of silica fume (SF) is less than 1%, and the content of fly ash (FA) is less than 10%.

4. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The fiber reinforcement includes one or more of polypropylene fiber, basalt fiber, polyvinyl alcohol fiber and steel-like fiber, and the fiber reinforcement content is <1.54%.

5. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The fiber reinforcement has a fiber length of 6-12 mm and a diameter of 10-20 μm.

6. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate superplasticizer mother liquor, with a water reduction rate >30% and a dosage <0.05%.

7. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The foaming agent is an animal protein-based foaming agent, prepared using a physical foaming method, with the foam density controlled at 40~60 kg / m³. 3 between.

8. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The weight percentage of foam is determined by the design density of the foamed concrete, specifically using the dry density method. The calculation formula is as follows: In the formula: ρ t The target dry density of the foamed concrete is defined by α; α is the mass coefficient of the cementitious material in the foamed concrete; M c M represents the required amount of cement. ma M represents the required amount of mineral admixtures. w ρ is the required amount of mixing water; β is the water-cement ratio used in the mix design; c ρ is the apparent density of cement. w β is the apparent density of water; M is the excess foam coefficient prepared by the foaming agent; f This refers to the amount of fresh foam used.

9. The foamed concrete composed of ultrafine powder and fiber reinforcement according to claim 1, characterized in that, The foamed concrete has an apparent density of 849 kg / m³, a 28-day compressive strength of 13.68 MPa, and an energy absorption value of 3.21 MJ / m³.

10. A method for preparing an ultrafine particle powder and fiber-reinforced composite, used to prepare foamed concrete of the ultrafine particle powder and fiber-reinforced composite as described in any one of claims 1 to 9, characterized in that, include: Place the powdered material of the foamed concrete mix into the mixing bucket according to the specified proportions, then pour in the mixing water mixed with the water-reducing agent, stir evenly, add the fiber reinforcement, and stir until a cement paste is formed. The amount of foam is calculated based on the dry density and bulk density method of foamed concrete. Then, the foaming agent is diluted at a ratio of 20 to 30 times. The foam density is controlled by adjusting the flow rate of the foaming water pump. Finally, the foaming equipment is started to produce foam. The cement paste and weighed foam are poured into a concrete mixer, mixed, and the wet density of the foam concrete is monitored in real time until the target density is reached. Then the addition of foam is stopped, resulting in foam concrete composed of ultrafine powder and fiber reinforcement.

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