A single-component alkali-activated slag foam lightweight concrete and a preparation method thereof

Abstract

The application discloses a single-component alkali-activated slag foam light concrete and a preparation method thereof. The concrete comprises a paste, a foaming agent, nano-silicon dioxide and a foam stabilizer. The paste comprises a cementing material and water. The cementing material comprises the following raw materials in percentage by mass: 88-92% of slag, 4-8% of sodium carbonate and 3-7% of slaked lime. The water-binder ratio is 0.35-0.45. The amount of the foaming agent is 0.5-1% of the mass of the paste. The amount of the nano-silicon dioxide is 1-2% of the mass of the foaming agent. The amount of the foam stabilizer is 0.1-0.3% of the mass of the paste. The application is composed of a dry mixture of a solid aluminosilicate precursor, a solid alkali source and an additive. The reaction process is triggered by directly adding water, the production steps are simplified, the cement consumption is reduced, and the carbon emission is reduced. The double-component alkali-activated cementing material overcomes the shortcomings of a strong alkaline activator, such as corrosion and high price.

Description

Technical Field

[0001] This invention belongs to the technical field of lightweight concrete materials, and relates to a single-component alkali-activated slag foam lightweight concrete and its preparation method. Background Technology

[0002] Foamed concrete is lightweight, provides thermal insulation, sound insulation, and fire resistance, and is widely used in civil engineering fields such as roadbed filling, roof insulation, and lightweight walls. However, traditional foamed concrete mainly uses cement as a binder, resulting in high energy consumption and carbon emissions during its production process, which presents limitations such as high energy consumption and high pollution. Therefore, using alkali-activated binders made from solid waste to prepare cementless foamed concrete can not only significantly reduce CO2 emissions but also achieve high-value utilization of solid waste, aligning with the green, environmentally friendly, and sustainable development concept of civil engineering, and demonstrating enormous application potential.

[0003] Currently, slag, as an industrial solid waste, is widely used in the field of alkali-activated materials due to its potential hydraulic activity and low cost. Alkali-activated slag adhesives are formed by activating the potential activity of slag using alkaline activators to create cementitious materials with high strength and durability. However, there is very little development of alkali-activated slag-based foamed concrete, and those that exist employ two-component systems. The activators are typically liquids such as sodium hydroxide solution or sodium silicate solution. Liquid activators present problems such as strong corrosivity, complex operation, and significant safety hazards during storage, transportation, and use. Summary of the Invention

[0004] To address the aforementioned issues, this invention provides a single-component alkali-activated slag foam lightweight concrete and its preparation method. The concrete consists of a dry mixture of a solid aluminosilicate precursor, a solid alkali source, and an admixture. The reaction process is triggered by the direct addition of water, simplifying the production process, reducing cement usage, and decreasing carbon emissions. This overcomes the disadvantages of two-component alkali-activated cementitious materials, such as the corrosiveness and high cost of the strongly alkaline activators.

[0005] The technical solution adopted in this invention is a single-component alkali-activated slag foam lightweight concrete, comprising:

[0006] The cementitious mortar comprises cementing materials and water (tap water). The cementing materials include the following raw materials by mass percentage: 88%-92% slag, 4%-8% sodium carbonate, and 3%-7% quicklime, with the total mass of the three components being 100%; the water-cement ratio is 0.35-0.45.

[0007] Foaming agent, the dosage is 0.5%-1% of the adhesive paste mass;

[0008] Nano-silica, used at a rate of 1%-2% of the foaming agent mass;

[0009] Foam stabilizer, the dosage is 0.1%-0.3% of the adhesive paste mass.

[0010] Furthermore, the foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate.

[0011] Furthermore, the foam stabilizer is polyvinyl alcohol.

[0012] A method for preparing a single-component alkali-activated slag foam lightweight concrete includes the following steps:

[0013] S1. Weigh the foaming agent according to the mass ratio and mix the foaming agent with water (tap water) evenly.

[0014] S2, Weigh out nano-silica according to the mass ratio, add nano-silica to the foaming agent in S1, and stir evenly;

[0015] S3 includes foaming and pulping;

[0016] The foaming process involves placing the S2 solution in a foaming machine to produce foam.

[0017] The pulping process involves mixing slag, sodium carbonate, quicklime, and water according to the mass ratio, stirring at 800-1000 rpm for 3-5 minutes, then adding polyvinyl alcohol as a foam stabilizer according to the mass ratio, and continuing to stir for 5-7 minutes to obtain the slurry.

[0018] S4. Quickly inject the foam obtained in the foaming step of S3 into the slurry obtained in the slurry preparation step of S3, and stir evenly to obtain mixed foamed concrete slurry.

[0019] S5. Pour the mixed foamed concrete slurry into the mold, cure it at room temperature for a period of time, then remove the mold and continue curing at room temperature to obtain the final product.

[0020] Furthermore, in S1, the foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate.

[0021] Furthermore, in S1, the mass ratio of sodium fatty alcohol polyoxyethylene ether sulfate to water is 1:10-20, and the mixture is stirred evenly at a rate of 300-500 rpm at room temperature (18-22℃).

[0022] Furthermore, in step S2, the mixture is stirred at a rate of 300-500 rpm at room temperature until homogeneous.

[0023] Furthermore, in S3, the air injection pressure of the foaming machine is 0.2-0.4 MPa.

[0024] Furthermore, in step S4, the mixture is stirred at a speed of 300-500 rpm for 1-2 minutes.

[0025] The beneficial effects of this invention are:

[0026] (1) This invention uses slag and other solid waste as raw materials to prepare single-component alkali-activated slag foam lightweight concrete, which provides a practical method for the utilization of solid waste, reduces the cost of cementitious materials, has good economic benefits, and conforms to the material design concept of efficient and economical resource utilization and green environmental protection.

[0027] (2) This invention utilizes a single-component alkali-activated lightweight slag foam concrete preparation method. The operation is simple, requiring no special treatment of the materials. It consists of a dry mixture of a solid aluminosilicate precursor, a solid alkali source, and an admixture. The reaction process is triggered by directly adding water. The process only requires uniform mixing of the solid activator and solid waste powder, adding water, stirring, pouring into molds, and vibration. This simplifies the production and construction process, reduces material mixing errors, and improves construction efficiency. It also possesses excellent mechanical properties, making it of significant research value and practical application significance. Compared to the more mature two-component alkali-activated lightweight slag foam concrete preparation method, this invention eliminates the need for pre-preparation of the activation solution, avoiding problems such as short setting time of cementitious materials, large shrinkage, corrosive alkaline solutions, complex operation, and negative impacts on workers and the environment. This facilitates its promotion in engineering practice and has promising engineering application prospects.

[0028] (3) The activator of the present invention is a low alkalinity activator. Both the foaming agent and the stabilizer are resistant to strong alkali, which can effectively solve the problem that foam is prone to breakage in a strong alkaline environment, improve the stability of foam in slurry, make the internal pore structure of foam concrete more regular, the bubble size uniform, and the uniformity higher, thereby improving the strength, construction efficiency and finished product quality of foam lightweight concrete, and also reducing its thermal conductivity. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the preparation method according to an embodiment of the present invention.

[0031] Figure 2 This is a photograph of the mixed foamed concrete slurry prepared in Example 7 of the present invention.

[0032] Figure 3 This is a photograph of the mixed foamed concrete slurry prepared in Comparative Example 1 of this invention.

[0033] Figure 4 This is a photograph of the mixed foamed concrete slurry prepared in Comparative Example 2 of this invention.

[0034] Figure 5 This is a photograph of the mixed foamed concrete slurry prepared in Comparative Example 3 of this invention. Detailed Implementation

[0035] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0036] Example 1,

[0037] A single-component alkali-activated slag foam lightweight concrete includes a binder, a foaming agent, nano-silica, and a foam stabilizer. The binder comprises cementitious materials and water. The cementitious materials include the following raw materials by mass percentage: 88%-92% slag, 4%-8% sodium carbonate, and 3%-7% quicklime, with the total mass of the three components being 100%. The water-cement ratio is 0.35-0.45. The amount of foaming agent is 0.5%-1% of the binder mass. The amount of nano-silica is 1%-2% of the foaming agent mass. The amount of foam stabilizer is 0.1%-0.3% of the binder mass.

[0038] The water-cement ratio refers to the mass ratio of water to cementitious materials (the total mass of slag, sodium carbonate, and quicklime).

[0039] The foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate.

[0040] The foam stabilizer is polyvinyl alcohol, which is added after the slag, sodium carbonate, quicklime and water are mixed to form a slurry.

[0041] In traditional foamed concrete, air bubbles tend to float or settle, leading to uneven pore structure and affecting the final material's performance. In highly alkaline environments (pH ≥ 13), ordinary foam films are prone to rupture, causing foam collapse and affecting the uniformity of bubble structure and material density control. The main functions of polyvinyl alcohol (PVA) are: ① Improving foam stability and preventing collapse. PVA enhances the extensibility and toughness of the foam film, making it less prone to rupture due to external disturbances or alkaline environments. ② Enhancing the bond between the slurry and bubbles, resulting in uniform bubble distribution. PVA strengthens the interfacial bond between the slurry and bubbles, reduces the bubble rise rate, prevents foam aggregation on the slurry surface, improves foam dispersion, and ensures uniform foam distribution, thereby improving the material's density uniformity. ③ Improving material strength and optimizing the mechanical properties of low-density foamed concrete. ④ Improving workability and fluidity, making the slurry easier to pump and increasing construction efficiency.

[0042] Example 2,

[0043] A method for preparing a single-component alkali-activated slag foam lightweight concrete, such as... Figure 1 As shown, it includes the following steps:

[0044] S1. Prepare the foaming agent: Weigh out the foaming agent at 0.8% of the mass of the adhesive paste. The foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate (AES). The mass ratio of the foaming agent to water (tap water) is 1:10. Stir and mix evenly at a speed of 300 rpm at room temperature (18-22℃).

[0045] S2, add nano-silica to the uniformly mixed foaming agent obtained in S1, the mass of nano-silica being 1.5% of the mass of the foaming agent; stir evenly at a rate of 300 rpm at room temperature (18-22℃).

[0046] S3: The foaming agent and nano-silica solution obtained in S2 are uniformly mixed and placed in a foaming machine for foaming at an injection pressure of 0.2 MPa to prepare foam. Simultaneously, slag (92% by mass), activator (4% sodium carbonate + 4% quicklime), and water (tap water) weighed according to a water-binder ratio of 0.4 are mixed and stirred at 800 rpm for 4 minutes. Polyvinyl alcohol is then added, and stirring continues for 6 minutes to obtain a slurry. The polyvinyl alcohol accounts for 0.2% of the slurry's mass. The slurry includes water, slag, sodium carbonate, and quicklime.

[0047] S4. Quickly inject the foam obtained in S3 into the slurry prepared in S3, and stir at 300 rpm for 2 minutes to obtain mixed foamed concrete slurry.

[0048] S5 involves pouring the mixed slurry, curing it at room temperature with the formwork in place for 24 hours, removing the formwork, and then curing it at room temperature for 28 days to obtain single-component alkali-activated slag foam lightweight concrete.

[0049] Example 3,

[0050] A method for preparing a single-component alkali-activated slag foam lightweight concrete includes the following steps:

[0051] S1. Prepare the foaming agent: Weigh out the foaming agent at 0.6% of the mass of the adhesive paste. The foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate. The mass ratio of the foaming agent to water (tap water) is 1:20. Stir and mix evenly at a speed of 500 rpm at room temperature (18-22℃).

[0052] S2, add nano-silica to the uniformly mixed foaming agent obtained in S1, the mass of nano-silica being 1.8% of the mass of the foaming agent; stir evenly at a rate of 500 rpm at room temperature (18-22℃).

[0053] S3: The foaming agent and nano-silica solution obtained in S2 are uniformly mixed and placed in a foaming machine for foaming at an injection pressure of 0.4 MPa to prepare foam. Simultaneously, slag (92% by mass), activator (5% sodium carbonate + 3% quicklime), and water (tap water) weighed according to a water-binder ratio of 0.35 are mixed and stirred at 1000 rpm for 3 minutes. Polyvinyl alcohol is then added, and stirring continues for 7 minutes to obtain a slurry. The polyvinyl alcohol accounts for 0.3% of the slurry's mass. The slurry includes water, slag, sodium carbonate, and quicklime.

[0054] S4. Quickly inject the foam obtained in S3 into the slurry prepared in S3, and stir at 500 rpm for 1 minute to obtain mixed foamed concrete slurry.

[0055] S5 involves pouring the mixed slurry, curing it at room temperature with the formwork in place for 24 hours, removing the formwork, and then curing it at room temperature for 28 days to obtain single-component alkali-activated slag foam lightweight concrete.

[0056] Example 4,

[0057] A method for preparing a single-component alkali-activated slag foam lightweight concrete includes the following steps:

[0058] S1. Prepare the foaming agent: Weigh out 0.5% of the foaming agent according to the mass of the adhesive paste. The foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate. The mass ratio of the foaming agent to water (tap water) is 1:15. Stir and mix evenly at a speed of 400 rpm at room temperature (18-22℃).

[0059] S2, add nano-silica to the uniformly mixed foaming agent obtained in S1, the mass of nano-silica being 1% of the mass of the foaming agent; stir evenly at a speed of 400 rpm at room temperature (18-22℃).

[0060] S3: The foaming agent and nano-silica solution obtained in S2 are mixed evenly and placed in a foaming machine for foaming. The air injection pressure is 0.3 MPa to prepare foam. Simultaneously, slag (90%), activator (6% sodium carbonate + 4% quicklime), and water (tap water) weighed according to a water-binder ratio of 0.45 are mixed and stirred at 900 rpm for 5 minutes. Then, polyvinyl alcohol is added, and stirring is continued for 5 minutes to obtain a slurry. The mass of polyvinyl alcohol is 0.1% of the slurry mass. The slurry includes water, slag, sodium carbonate, and quicklime.

[0061] S4. Quickly inject the foam obtained in S3 into the slurry prepared in S3, and stir at 400 rpm for 1.5 min to obtain mixed foamed concrete slurry.

[0062] S5 involves pouring the mixed slurry, curing it at room temperature with the formwork in place for 24 hours, removing the formwork, and then curing it at room temperature for 28 days to obtain single-component alkali-activated slag foam lightweight concrete.

[0063] The amounts of slag, activator (sodium carbonate + quicklime), water-cement ratio, foaming agent (sodium fatty alcohol polyoxyethylene ether sulfate), nano silica and polyvinyl alcohol added in Examples 5-11 are shown in Table 1. The remaining steps are the same as in Example 4.

[0064] Comparative Example 1,

[0065] Step S2 is omitted, i.e., no nano-silica is added; the remaining steps are the same as in Example 7.

[0066] Comparative Example 2,

[0067] In step S3, polyvinyl alcohol is not added; the remaining steps are the same as in Example 7.

[0068] Comparative Example 3,

[0069] Step S2 is omitted, i.e., no nano-silica is added; and in step S3, no polyvinyl alcohol is added; the remaining steps are the same as in Example 7.

[0070] Comparative Example 4,

[0071] The activator was only sodium silicate, and the amount of sodium silicate used was the same as the molar alkalinity (Na2O equivalent) of the activator (sodium carbonate + quicklime) in Example 7. The remaining steps were the same as in Example 7.

[0072] Comparative Example 5,

[0073] The activator is sodium hydroxide, and the amount of sodium hydroxide used is the same as the molar alkalinity (Na2O equivalent) of the activator (sodium carbonate + quicklime) in Example 7. The remaining steps are the same as in Example 7.

[0074] Table 1. Amounts of each raw material used in Examples 2-11

[0075]

[0076] Dry density, compressive strength, and thermal conductivity were determined for single-component alkali-activated cementitious material foam specimens after 28 days of curing. Compressive strength and dry density were tested according to the methods specified in standard JG / T266-2011 "Foamed Concrete," and thermal conductivity was tested according to GB / T10294-2008 "Determination of Steady-State Thermal Resistance and Related Properties of Insulation Materials - Protective Hot Plate Method." The test results are shown in Table 2.

[0077] Table 2. Test results of Examples 2-11 and Comparative Examples 1-3

[0078]

[0079] When the slag content is 88%, sodium carbonate content is 7%, quicklime content is 5%, water-cement ratio is 0.35, foaming agent is 0.7% of the mortar mass, nano-silica is 1.2% of the foaming agent mass, and polyvinyl alcohol is 0.15% of the mortar mass, the 28-day compressive strength of the single-component alkali-activated slag foam lightweight concrete is 3.1 MPa, and the dry density is 470 kg / m³. 3 Its thermal conductivity is 0.069 W / (m·K).

[0080] Photographs of the mixed foamed concrete slurry obtained at the same preparation time in Comparative Examples 1, 2, 3 and S4 of Example 7 are shown below. Figures 2-5 As shown in the figure, the mixed foamed concrete slurry obtained in Example 7 has better uniformity. Compared with Comparative Examples 1, 2 and 3, the foam in Example 7 did not combine to form larger bubbles. At the same time, no settling occurred. Adding a single foam stabilizer or not adding a foam stabilizer caused the slurry to settling before it hardened, indicating that Example 7 has a better foam stabilizing effect, thereby improving the strength of the foamed lightweight concrete and reducing the thermal conductivity.

[0081] If sodium dodecylbenzenesulfonate (SDBS) is used as the foaming agent in this embodiment of the invention, it has strong foaming ability, but the foam is prone to coalescence, affecting the uniformity of the bubbles. Its toxicity and irritation are both higher than AES, and its biodegradability is poor. If sodium α-alkenylsulfonate (AOS) is used as the foaming agent in this embodiment of the invention, it has good alkaline stability, but the foam fineness is not as good as AES. Its toxicity and irritation are lower than SDBS but higher than AES. It is biodegradable, but the degree of degradation is worse than AES.

[0082] If nano-titanium dioxide (TiO2) replaces the nano-silica in the embodiments of this invention, the cost is higher and the impact on the slurry is greater (it is prone to agglomeration and poor dispersibility, leading to a decrease in foam stability; it may inhibit hydration, increase viscosity, and affect fluidity). If ultrafine calcium carbonate (CaCO3) replaces the nano-silica in the embodiments of this invention, the particles are larger, and the foam stabilizing effect is not as good as that of SiO2. If hydroxyethyl cellulose (HEC) replaces the nano-silica in the embodiments of this invention, the alkaline stability is insufficient, and it is easy to decompose.

[0083] If sodium carboxymethyl cellulose (CMC-Na) replaces polyvinyl alcohol in the embodiments of the present invention, the alkali resistance is weak; if hydroxypropyl methyl cellulose (HPMC) replaces polyvinyl alcohol in the embodiments of the present invention, a higher addition amount is required to achieve the effect of PVA. If hydroxyethyl cellulose (HEC) replaces polyvinyl alcohol in the embodiments of the present invention, the flexibility is poor and the improvement of slurry strength is insufficient.

[0084] In highly alkaline environments (pH≥13), bubble films are prone to collapse due to high permeability and low film strength. Ordinary foaming agents are easily degraded, leading to foam rupture or disappearance, affecting the material's volume stability, density control, and strength. Traditional foam stabilizers (such as cellulose or single nanomaterials) struggle to maintain the foam structure in highly alkaline environments. In traditional foamed concrete systems, insufficient bubble film strength leads to foam fusion and collapse, consequently affecting material uniformity. This invention addresses the synergistic effect of nano-silica and polyvinyl alcohol: SiO2 enhances the rigid support of the foam, preventing physical rupture; PVA enhances the flexibility of the foam, preventing collapse or chemical degradation due to external forces. This dual physical and chemical synergistic stabilizing effect ensures the foam remains stable and resistant to rupture even in highly alkaline environments, ultimately improving the overall performance of the foamed concrete. Combining physical support and film reinforcement properties, the strength and flexibility of the foam film are improved, significantly enhancing foam stability in highly alkaline environments (pH≥13) and effectively overcoming the foam collapse problem.

[0085] Table 3 Experimental results of the activator in the embodiments of the present invention and the comparative examples.

[0086]

[0087] Traditional alkaline activation material systems typically employ liquid activators (such as sodium silicate and sodium hydroxide) or solid sodium silicate and sodium hydroxide. However, these activators readily interact with foam, leading to foam breakage and making it difficult to ensure uniform bubble distribution. Secondly, these strongly alkaline activators are prone to gelation reactions during alkaline activation, affecting the fluidity of the slurry and the uniform mixing of the foam. This invention employs a combined activation system of sodium carbonate and quicklime, which can slow down the hydration reaction rate between the sodium carbonate activator and the precursor, reducing the early viscosity of the slurry and ensuring uniform foam dispersion. The experimental results are shown in Table 3. Simultaneously, the addition of quicklime provides additional Ca2+. 2+ Ions react with slag to form a denser CSH gel, improving material strength without damaging the foam structure. The combination of sodium carbonate and quicklime creates a highly efficient alkali-activated reaction. Simultaneously, the addition of nano-SiO2 and polyvinyl alcohol optimizes the compatibility between the foaming agent and the slurry, ensuring uniform foam distribution and slurry bonding. Stepwise mixing at room temperature and pressure enables efficient preparation of foamed concrete, significantly reducing energy consumption and cost. This invention, through the combination of a single-component alkali-activated system and a dual foam stabilization strategy, achieves comprehensive optimization of lightweight foamed concrete in terms of material properties, construction efficiency, and environmental characteristics. This preparation method not only simplifies the production process but also significantly improves the mechanical properties and thermal insulation effect of the product, making it an economical, efficient, and green method for preparing lightweight concrete. The resulting foamed concrete is lightweight, heat-insulating, sound-insulating, and fire-resistant, and can be used for roadbed filling projects, roof insulation, lightweight walls, etc.

[0088] Traditional phosphogypsum or autoclaved foam concrete requires high-temperature and high-pressure curing to ensure the material's strength development, increasing production costs and energy consumption. In cold regions or high-humidity environments, the curing time is difficult to control, affecting construction efficiency. This invention optimizes the alkali activation system and foam stabilization system, enabling the material to cure at room temperature, achieving low energy consumption and room-temperature curing characteristics, improving the material's ease of construction and environmental adaptability. The slow-release properties of sodium carbonate ensure that the material solidifies within a reasonable time, avoiding construction difficulties caused by excessively rapid solidification. The filling effect of nano-silica reduces porosity defects and improves the material's early strength.

[0089] Table 4. Experimental results of the foaming agent in the embodiments of the present invention and the comparative example.

[0090]

[0091] Comparative Example 6,

[0092] The foaming agent is plant protein (soybean), and the amount of foaming agent used is 0.7% of the mass of the adhesive. Steps S3-S5 are the same as in Example 7.

[0093] Comparative Example 7,

[0094] The foaming agent is animal protein, and the amount of foaming agent used is 0.7% of the mass of the adhesive paste. Steps S3-S5 are the same as in Example 7.

[0095] As shown in Table 4, traditional foamed concrete uses plant or animal protein as a foaming agent. However, under highly alkaline conditions (pH ≥ 13), the foam stability decreases, making it prone to collapse. This also results in insufficient foam uniformity, affecting the strength of the foamed concrete. The embodiments of this invention utilize AES, which has strong alkali resistance (pH ≥ 13), making the foam less prone to collapse in alkali-activated systems. The foam is finer, more uniform, has good compatibility with foam stabilizers, and exhibits strong foam durability.

[0096] This invention employs anionic synthetic surfactant sodium fatty alcohol polyoxyethylene ether sulfate (AES) as a foaming agent, which possesses excellent foaming properties and alkali resistance, ensuring the stability of the foam in alkali-activated cementitious material systems. Simultaneously, nano-SiO2 is introduced, utilizing its high specific surface area and colloidal stabilizing effect to adsorb onto the foam-film interface, enhancing the foam film thickness and rigidity, and delaying the rupture of the foam liquid film. Polyvinyl alcohol (PVA) can form a stretchable "elastic network structure" between the foam films, synergistically working with nano-SiO2 to further improve the foam's burst resistance and early-stage volume stability. The synergistic effect of these three components allows the foam to maintain good stability even in highly alkaline environments (pH>13) and exhibits excellent compatibility with alkali-activated slag reaction processes. As shown in Table 4, the 1-hour settling distance of the AES foaming agent used in this invention is much smaller than that of the protein-based foaming agent system, and the 28-day compressive strength is much higher than that of the protein-based foaming agent system. As shown in Tables 1 and 2, the synergistic stabilization mechanism of AES + nano-SiO2 + PVA has significant advantages in improving the mechanical properties and controlling the microstructure of alkaline slag foamed concrete.

[0097] Extensive experimental research has shown that the AES + SiO2 + PVA combination exhibits the best alkali resistance, foam stability, slurry-foam bonding strength, and mechanical properties, making it more suitable for high-alkalinity foamed concrete systems. Specifically:

[0098] (1) Complementary effect of interface physical structure: Nano-silica particles are oriented on the surface of the foam film to form a "particle protective film layer", which provides micro-rigid support and improves tensile strength; Polyvinyl alcohol forms a continuous polymer network in the liquid phase of the foam film, which effectively improves the extensibility and flexibility of the film; The two work together to form a "rigid-flexible-elastic" three-phase composite foam film structure, which enables the foam system to have both high crack resistance and collapse resistance.

[0099] (2) Synergistic stability improvement in alkaline environment: Polyvinyl alcohol is at risk of partial chain breakage and decreased film stability in a highly alkaline slag activation system. Nano-silica can wrap part of the PVA chain through hydrogen bonds or van der Waals forces to form a composite structure of "particle protective film + flexible film formation", which improves the structural stability in alkaline system. Nano-silica can also partially adsorb foaming agent molecules, improve the retention rate of foam surfactant and film surface adhesion, thereby inhibiting foam merging and drainage.

[0100] The AES+nano-SiO2+PVA foaming stabilization system of this invention breaks through the limitations of traditional single polymer modification technology. For the first time, it realizes a rigid-flexible composite synergistic foam film stabilization mechanism in alkali-activated foamed concrete, significantly improving the stability of the foam structure and demonstrating significant technological advancement and industrial application potential.

[0101] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention are included within the scope of protection of the present invention.

Claims

1. A single-component alkali-activated slag foam lightweight concrete, characterized in that, include: The mortar comprises cementitious materials and water. The cementitious materials include the following raw materials by mass percentage: 88%-92% slag, 4%-8% sodium carbonate, and 3%-7% quicklime, with the total mass of the three components being 100%; the water-cement ratio is 0.35-0.

45. Foaming agent, the dosage is 0.5%-1% of the adhesive paste mass; Nano-silica, used at a rate of 1%-2% of the foaming agent mass; Foam stabilizer, the dosage is 0.1%-0.3% of the adhesive paste mass.

2. The single-component alkali-activated slag foam lightweight concrete according to claim 1, characterized in that, The foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate.

3. The single-component alkali-activated slag foam lightweight concrete according to claim 1, characterized in that, The foam stabilizer is polyvinyl alcohol.

4. The method for preparing a single-component alkali-activated slag foam lightweight concrete as described in claim 1, characterized in that, Includes the following steps: S1. Weigh the foaming agent according to the mass ratio and mix the foaming agent with water evenly; S2, Weigh out nano-silica according to the mass ratio, add nano-silica to the foaming agent in S1, and stir evenly; S3 includes foaming and pulping; The foaming process involves placing the S2 solution in a foaming machine to produce foam. The pulping process involves mixing slag, sodium carbonate, quicklime, and water according to the mass ratio, stirring at 800-1000 rpm for 3-5 minutes, then adding polyvinyl alcohol as a foam stabilizer according to the mass ratio, and continuing to stir for 5-7 minutes to obtain the slurry. S4. Quickly inject the foam obtained in the foaming step of S3 into the slurry obtained in the slurry preparation step of S3, and stir evenly to obtain mixed foamed concrete slurry. S5. Pour the mixed foamed concrete slurry into the mold, cure it at room temperature for a period of time, then remove the mold and continue curing at room temperature to obtain the final product.

5. The method for preparing a single-component alkali-activated slag foam lightweight concrete according to claim 4, characterized in that, In S1, the foaming agent is sodium fatty alcohol polyoxyethylene ether sulfate.

6. The method for preparing a single-component alkali-activated slag foam lightweight concrete according to claim 5, characterized in that, In S1, the mass ratio of sodium fatty alcohol polyoxyethylene ether sulfate to water is 1:10-20, and the mixture is stirred evenly at a rate of 300-500 rpm at room temperature.

7. The method for preparing a single-component alkali-activated slag foam lightweight concrete according to claim 4, characterized in that, In step S2, the mixture is stirred at a rate of 300-500 rpm at room temperature until homogeneous.

8. The method for preparing a single-component alkali-activated slag foam lightweight concrete according to claim 4, characterized in that, In S3, the air injection pressure of the foaming machine is 0.2-0.4 MPa.

9. The method for preparing a single-component alkali-activated slag foam lightweight concrete according to claim 4, characterized in that, In step S4, the mixture is stirred at 300-500 rpm for 1-2 minutes.

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