A negative carbon environmental protection multi-layer reinforced raw soil base prefabricated wallboard

Abstract

The application discloses a kind of negative carbon environmental protection multilayer reinforced raw soil base prefabricated wallboards, the multilayer reinforced raw soil base prefabricated wallboards include two composite wallboards and the functional layer being arranged in composite wallboard, the composite wallboard includes two raw soil wallboards and the cellulose bonding layer being applied to the middle of two prefabricated wallboards.The application is aimed at the deficiencies of prior art, and is committed to improving the high energy consumption, high pollution, high emission problems existing in the production process of existing reinforced concrete wallboard.

Description

Technical Field

[0001] This invention belongs to the field of building technology. Specifically, this invention relates to a carbon-negative, environmentally friendly, multi-layer reinforced rammed earth precast wall panel. Background Technology

[0002] In recent years, environmental protection and sustainable development have become important trends in wall panel technology. Concepts such as pollution reduction and carbon reduction, bamboo as a substitute for plastic, and green, low-carbon recycling have gained widespread acceptance. However, in the wall panel production field, the market currently mostly uses reinforced concrete precast panels, which suffer from high energy consumption, high pollution, and high emissions during production. Therefore, earthen-based wall panels, produced using locally sourced raw soil from urban construction, combined with magnesium oxide as a green curing agent, sisal and bamboo fiber as reinforcing materials, and carbon dioxide absorption to enhance material performance, offer a more effective approach and feasible research results for solving these problems. Furthermore, the performance requirements of different building materials can be adjusted through interlayering. Besides being low-cost, low-energy-consumption, and pollution-free during production, earthen-based wall panels also possess better heat storage and insulation properties than concrete wall panels. After reaching a certain service life, they can be modified into fertilizer for agricultural production, making them more environmentally friendly and maximizing economic benefits. Summary of the Invention

[0003] This invention aligns with the environmental protection and sustainable development principles required in the wall panel production industry, providing a greener, more environmentally friendly, and more economical method for wall panel production based on activated magnesium oxide carbonized clay-based materials. Addressing the shortcomings of existing technologies, this invention aims to improve the high energy consumption, high pollution, and high emissions problems present in the current reinforced concrete wall panel production process. The technical solution is as follows: A carbon-negative, environmentally friendly, multi-layer reinforced rammed earth precast wall panel, comprising two layers of rammed earth wall panels and a functional layer disposed between the composite wall panels, wherein the composite wall panel comprises two layers of rammed earth wall panels and a cellulose bonding layer coated between the two precast wall panels.

[0004] By weight, the raw earth wall panel raw materials include: 10-25 parts of active magnesium oxide, 10-20 parts of cement, 3-6 parts of fly ash, 10-20 parts of dry sand, 0.1-0.3 parts of nanocellulose, 1-2 parts of sisal, 1-2 parts of bamboo fiber, 0.10-0.20 parts of cellulose, and 35-85 parts of raw earth.

[0005] The rammed earth wall panel is formed by pressing a mixture of raw materials with low active magnesium oxide cement content and a mixture of raw materials with high active magnesium oxide cement content into low magnesium oxide layer, medium magnesium oxide layer and high magnesium oxide layer in an upward order. The active magnesium oxide is highly active light-burned magnesium oxide, the cement is 32.5 grade ordinary silicate cement, the fly ash is experimental grade 1 fly ash, the sisal has a length of 5-10 mm, the bamboo fiber is prepared from raw materials such as moso bamboo and green bamboo, and the surface of the bamboo fiber is modified by 3-glycidyl etheroxypropyltrimethoxysilane, the nanocellulose is nanofibrillated cellulose produced based on raw material bleached conifer sulfate pulp, the cellulose used is methylcellulose, the dry sand is natural sand with a particle size of less than 2 mm, and the raw soil has a particle size of less than 2 mm.

[0006] The active magnesium oxide is highly active light-burned magnesium oxide, the cement is 32.5 grade ordinary silicate cement, the fly ash is experimental grade 1 fly ash, the sisal has a length of 20-30 mm, the bamboo fiber is prepared from moso bamboo and green bamboo, and the surface of the bamboo fiber is modified by 3-glycidyl etheroxypropyltrimethoxysilane, the nanocellulose is nanofibrillated cellulose produced based on bleached conifer sulfate pulp, the cellulose used is methylcellulose, the dry sand is natural sand with a particle size of less than 2 mm, and the raw soil has a particle size of less than 2 mm.

[0007] The high-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 25:15:6:15:0.15:2:1.5:39. The medium-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 20:15:6:15:0.15:2:1.5:44. The low-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 15:15:6:15:0.15:2:1.5:49.

[0008] The composite wall panel forming steps include: S1, prepare raw material mixtures with three different active magnesium oxide dosages; S2. Soak two types of sisal fibers with lengths of 5-10 mm and 20-30 mm in 1% NaOH solution for 30 minutes, then wash with clean water and air dry. Dry bamboo fibers in an oven at 103℃ for about 10 hours until constant weight and set aside. Prepare a 1wt% concentration of 3-glycidyl etheroxypropyltrimethoxysilane ethanol solution as a modifier. Take 100g of bamboo fibers, place the required modifier solution and bamboo fibers in a flask, heat to 60℃ and maintain constant temperature, stir with a magnetic stirrer for 3 hours. Wash the modified bamboo fibers repeatedly with distilled water 3 times, extract to remove excess 3-glycidyl etheroxypropyltrimethoxysilane, and then dry in an oven at 103℃ for 24 hours. After removal, seal in a vacuum bag and store for later use. S3, add water to the mixture of the three raw materials in S1 and stir evenly to form a mixture; S4, add sisal and bamboo fibers of two lengths, 5-10mm and 20-30mm, to the mixture in three batches according to the corresponding amounts and mix well; S5, three raw material mixtures with different active magnesium oxide content are filled into molds, manually tamped and a certain load is applied, and pressed into shape to form raw earth wall panels. S6. Demolding is performed using a demolding machine, and the mixture is immediately placed in a carbonization box for carbonization and curing. The amount of water added is 20% to 30% of the total mass of the mixture. The carbonization box is set with the following parameters: CO2 concentration 10% to 30%, temperature 20 to 30°C, and humidity 60% to 80%. S7. Mix cellulose with water to prepare a solution with a mass fraction of 20% to 30%. After standing for half an hour, apply the solution to the side of the raw earth wall panel with a lower content of active magnesium oxide cement. Adhere the raw earth wall panels in pairs to form a composite wall panel. Finally, brush a layer of waterproof protective agent on the surface of the composite wall panel.

[0009] Two grooves for installing steel reinforcement bars are formed on the high magnesium oxide layer.

[0010] The functional layer is a gypsum hollow wall panel.

[0011] The functional layer is an asbestos-free calcium silicate board.

[0012] Compared with traditional technologies, the present invention has the following advantages: (1) Compared with traditional reinforced concrete precast wall panels, the earthen wall panels used in this invention combine the advantages of traditional earthen buildings with modern scientific and innovative modification technology. Active magnesium oxide is used as a green and efficient reinforcing agent, and bamboo fiber and sisal fiber are used to replace traditional steel fiber and plastic fiber (polypropylene, etc.). On the basis of improving the mechanical properties of earthen wall panels, the overall green material utilization is realized, making the earthen wall panels more economical and environmentally friendly than traditional reinforced concrete wall panels, and responding to my country's policy of replacing plastic with bamboo, reducing carbon emissions and pollution.

[0013] (2) The multi-layer reinforced structure adopted in this invention is more adaptable to different building environments than traditional precast concrete wall panels. The intermediate layer can be an additional functional layer on the basis of the composite wall panel. For example, in building sites with strict sound insulation requirements, the multi-layer reinforced rammed earth precast wall panel of this invention can be changed from a composite wall panel to a composite wall panel-gypsum board / polyester fiber sound-absorbing board-composite wall panel.

[0014] (3) The active magnesium oxide used in this invention is a reinforcing agent, and it adopts the characteristics of layered pressing and green bonding after carbonization. It utilizes the difference in magnesium oxide dosage to offset the pressure difference of ordinary wall panels, which to a certain extent inhibits wall cracking and improves the wall's anti-fracture performance. Moreover, when the active magnesium oxide is carbonized in the rammed earth wall panel, it generates a variety of magnesium carbonates, such as trihydrate magnesia, spheroidal magnesia, and hydrous magnesia. These carbonization products can greatly improve the mechanical properties of the precast wall panels and greatly improve the development bottleneck of poor water resistance and low material strength of traditional rammed earth buildings. This allows the rammed earth wall panels to maintain their original advantages (low cost, wide availability, low emissions, strong insulation, etc.) while further improving their usability. At the same time, the dosage ratio of the active magnesium oxide curing agent in the wall panel can be adjusted according to different usage scenarios to achieve the purpose of improving durability and reducing costs.

[0015] (4) In the multi-layer reinforced structure, the present invention uses cellulose and nanocellulose for bonding and filling the gaps between and within the wall panels. Cellulose is a natural organic material extracted from plant fibers that is low in cost, healthy, safe, environmentally friendly and has excellent bonding performance. Furthermore, the bonding performance of cellulose can be adjusted by regulating its concentration, pH value and additives, so that the earthen wall panels in the present invention can adapt to different types of building needs.

[0016] (5) The nanocellulose added to the carbonized virgin earth wall panel is also a natural organic material derived from plant fibers. It is nano-sized cellulose obtained by treating fibers through physical and chemical methods. Its addition can significantly improve the mechanical properties of the carbonized virgin earth wall panel, further reduce the environmental impact of the carbonized virgin earth wall panel, and improve the durability of the carbonized virgin earth wall panel. The nanocellulose effectively fills the pores in the precast wall panel, improving the impermeability, crack resistance, and weather resistance of the carbonized virgin earth wall panel, thus significantly extending the service life of the carbonized virgin earth wall panel.

[0017] (6) The utilization of sisal and bamboo fibers is due, on the one hand, to their wide availability, renewability, low price, and environmental friendliness; on the other hand, it is due to their superior performance. Compared to steel fibers, plastic fibers, or mineral fibers in traditional concrete wall panels, sisal and bamboo fibers have the characteristics of low density, high elasticity, salt and alkali resistance, and high tensile strength among plant fibers, and they also have the advantage of low shrinkage in both dry and wet environments. Therefore, compared to traditional reinforced concrete wall panels, the multi-layer reinforced rammed earth precast wall panels described in this invention have greater advantages in terms of economy, performance, and sustainable development.

[0018] (7) By opening grooves for installing steel reinforcement keel in the high magnesium oxide layer, on the one hand, it is beneficial to install the multi-layer reinforced soil foundation precast wall panel more firmly, and on the other hand, the higher magnesium oxide content can effectively prevent the carbonization of steel reinforcement keel. Attached Figure Description

[0019] The present application will be further described below with reference to the accompanying drawings and embodiments. In the accompanying drawings: Figure 1 Flowchart of composite wall panel preparation method Figure 2 Schematic diagram of composite wall panels Figure 3 Schematic diagram of multi-layer reinforced rammed earth foundation precast wall panel structure 1. Composite wall panel; 2. Earthen wall panel; 3. Functional layer. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this application clearer, the following detailed description is provided in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the scope of this application. Furthermore, the embodiments and features described herein can be combined with each other unless otherwise specified.

[0021] To obtain the ideal green rammed earth wall panel, this invention employs three rammed earth mixtures with different amounts of magnesium oxide (MgO) activity. The highest MgO content acts on the outermost layer, a relatively high MgO content on the middle layer, and the lowest MgO content on the inner layer. The aim is to use the difference in MgO content to offset the inherent pressure difference of ordinary wall panels, thereby inhibiting wall cracking to some extent and improving the wall's fracture resistance. Furthermore, the highest MgO content effectively prevents the carbonization of the reinforcing steel reinforcement. The green reinforcement adopted enhances the wall's crack resistance, bending resistance, and shear resistance through the three-dimensional coupling distribution of fibers of different lengths within the wall. Additionally, the addition of fibers increases the friction between material particles, demonstrating a significant increase in the mechanical properties and durability of the rammed earth wall panel during the experimental phase.

[0022] The multi-layer reinforced rammed earth wall panel of the present invention enhances the strength of the wall by absorbing carbon dioxide to produce high-strength and dense carbonization products. Compared with traditional reinforced concrete wall panels, it is more environmentally friendly, reduces energy consumption and emissions while obtaining negative carbon benefits. It is also stronger and more durable than the rammed earth bricks used in traditional rammed earth buildings. Furthermore, it is more environmentally friendly than the firing of rammed earth bricks and more time-saving and labor-saving than the ramming method.

[0023] The multi-layer reinforced rammed earth precast wall panel includes two layers of composite wall panel 1 and a functional layer disposed between the composite wall panel 1. The composite wall panel 1 includes two layers of rammed earth wall panel 2 and a cellulose bonding layer 3 coated between the two layers of rammed earth wall panel 2.

[0024] By weight, the raw materials of the earthen wall panel (2) include: 10-25 parts of active magnesium oxide, 10-20 parts of cement, 3-6 parts of fly ash, 10-20 parts of dry sand, 0.1-0.3 parts of nanocellulose, 1-2 parts of sisal, 1-2 parts of bamboo fiber, 0.10-0.20 parts of cellulose, and 35-85 parts of raw soil.

[0025] Earthen wall panel 2 is formed by pressing a mixture of raw materials with low active magnesium oxide cement content and a mixture of raw materials with high active magnesium oxide cement content into low magnesium oxide layer, medium magnesium oxide layer and high magnesium oxide layer in an upward sequence. The active magnesium oxide is highly active light-burned magnesium oxide, the cement is 32.5 grade ordinary silicate cement, the fly ash is experimental grade 1 fly ash, the sisal length is 5-10mm, the bamboo fiber is prepared from raw materials such as moso bamboo and green bamboo, and the surface of the bamboo fiber is modified by 3-glycidyl etheroxypropyltrimethoxysilane. The nanocellulose is nanofibrillated cellulose produced based on raw material bleached conifer sulfate pulp, the cellulose used is methylcellulose, the dry sand is natural sand with a particle size of less than 2mm, and the raw soil has a particle size of less than 2mm.

[0026] The active magnesium oxide is highly active light-burned magnesium oxide, the cement is 32.5 grade ordinary silicate cement, the fly ash is experimental grade 1 fly ash, the sisal length is 20-30 mm, the bamboo fiber is prepared from moso bamboo and green bamboo as raw materials, and the surface of the bamboo fiber is modified by 3-glycidyl etheroxypropyltrimethoxysilane. The nanocellulose is nanofibrillated cellulose produced based on bleached conifer sulfate pulp, and the cellulose used is methylcellulose. The dry sand is natural sand with a particle size of less than 2 mm, and the raw soil has a particle size of less than 2 mm.

[0027] The high-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 25:15:6:15:0.15:2:1.5:39. The medium-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 20:15:6:15:0.15:2:1.5:44. The low-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 15:15:6:15:0.15:2:1.5:49.

[0028] The molding steps of composite wall panel 1 include: S1, prepare raw material mixtures with three different active magnesium oxide dosages; S2. Soak two types of sisal fibers with lengths of 5-10 mm and 20-30 mm in 1% NaOH solution for 30 minutes, then wash with clean water and air dry. Dry bamboo fibers in an oven at 103℃ for about 10 hours until constant weight and set aside. Prepare a 1wt% concentration of 3-glycidyl etheroxypropyltrimethoxysilane ethanol solution as a modifier. Take 100g of bamboo fibers, place the required modifier solution and bamboo fibers in a flask, heat to 60℃ and maintain constant temperature, stir with a magnetic stirrer for 3 hours. Wash the modified bamboo fibers repeatedly with distilled water 3 times, extract to remove excess 3-glycidyl etheroxypropyltrimethoxysilane, and then dry in an oven at 103℃ for 24 hours. After removal, seal in a vacuum bag and store for later use. S3, add water to the mixture of the three raw materials in S1 and stir evenly to form a mixture; S4, add sisal and bamboo fibers of two lengths, 5-10mm and 20-30mm, to the mixture in three batches according to the corresponding amounts and mix well; S5, three different active magnesium oxide content raw material mixtures are filled into molds, manually tamped and a certain load is applied, and pressed into shape to form raw earth wall panels (2). S6. Demolding is performed using a demolding machine, and the mixture is immediately placed in a carbonization box for carbonization and curing. The amount of water added is 20% to 30% of the total mass of the mixture. The carbonization box is set with the following parameters: CO2 concentration 10% to 30%, temperature 20 to 30°C, and humidity 60% to 80%. S7, mix cellulose with water to prepare a solution with a mass fraction of 20% to 30%, let it stand for half an hour and then apply it to the side of the raw earth wall panel (2) with a low active magnesium oxide cement content. Adhere the raw earth wall panels 2 in pairs to form a composite wall panel 1. Finally, brush a layer of waterproof protective agent on the surface of the composite wall panel 1.

[0029] Two grooves for installing steel reinforcement joists are provided on one side of the high magnesium oxide layer.

[0030] The functional layer is made of gypsum hollow wall panels.

[0031] The functional layer is made of asbestos-free calcium silicate board.

[0032] Figure 2 This is a schematic diagram of a composite wall panel. The interlayer adhesive used in this invention is methylcellulose. On one hand, it increases the surface adhesion of the material, improving its tensile strength and durability. Simultaneously, it increases the cellulose fiber content in the wall material, thereby enhancing the crack resistance of the building material. This cellulose fiber can also effectively control the shrinkage of the building material and effectively prevent crack formation. On the other hand, cellulose as a binder is non-toxic, simple to prepare, and inexpensive, further reducing the manufacturing cost of earthen wall panels.

[0033] In practical use, a single multi-layer reinforced rammed earth precast wall panel is typically a rectangular panel with a thickness exceeding 20mm. Therefore, two grooves are cut along both long sides. Depending on the size requirements, two or more multi-layer reinforced rammed earth precast wall panels are used together. The grooves are used in conjunction with I-beam-shaped steel reinforcement framing for the outer layer assembly of the rammed earth wall panel. In actual use, only one side of the multi-layer reinforced rammed earth precast wall panel needs to have a groove. Therefore, one of the two composite wall panels that make up the multi-layer reinforced rammed earth precast wall panel has a groove, and correspondingly, one of the two rammed earth wall panels that make up the composite wall panel has a groove. Figure 3 is a schematic diagram of a multi-layer reinforced precast wall panel structure, in which... Figure 3 The middle functional layer consists of gypsum hollow wall panels, forming a high-sound-insulating wall panel. Figure 3 The functional layer in section b is made of asbestos-free calcium silicate board, forming a high-strength fireproof and heat-insulating wall panel.

[0034] In Example 1, the thickness of the lower layer of raw earth wall panel is 20cm. The thickness of the first pressing is 10cm, and the admixtures include 15 parts of active magnesium oxide, 15 parts of cement, 6 parts of fly ash, 15 parts of dry sand, 1.5 parts of sisal of two different lengths, 2 parts of bamboo fiber, 0.15 parts of nanocellulose, and 49 parts of raw earth. The thickness of the second pressing is 10cm, and the admixtures include 20 parts of active magnesium oxide, 15 parts of cement, 6 parts of fly ash, 15 parts of dry sand, 1.5 parts of sisal of two different lengths, 2 parts of bamboo fiber, 0.15 parts of nanocellulose, and 49 parts of raw earth. The thickness of the upper layer of raw earth wall panels is 20cm, of which the first pressing is 10cm thick and the admixtures include 20 parts of active magnesium oxide, 15 parts of cement, 6 parts of fly ash, 15 parts of dry sand, 1.5 parts of sisal of two different lengths, 2 parts of bamboo fiber, 0.15 parts of nanocellulose, and 44 parts of raw earth; the second pressing is 10cm thick and the admixtures include 15 parts of active magnesium oxide, 15 parts of cement, 6 parts of fly ash, 15 parts of dry sand, 1.5 parts of sisal of two different lengths, 2 parts of bamboo fiber, 0.15 parts of nanocellulose, and 49 parts of raw earth. The intermediate layer is the functional layer, which is a gypsum hollow wall panel (10cm thick), comprising glass fiber, perlite, desulfurized gypsum, fly ash, water, and cement. The mass percentages of each component are as follows: glass fiber 2-2.5 parts, perlite 1.5-2 parts, desulfurized gypsum 45-50 parts, fly ash 4-7 parts, water 1.2-1.5 times the mass of desulfurized gypsum, and cement 0.1-0.15 times the total mass.

[0035] According to the preparation method and proportion of Embodiment 1 above, the multi-layer reinforced raw soil precast wall panel includes multiple mixed fiber layers that are bidirectionally interwoven in the transverse and longitudinal directions (the three layers shown in the figure are only examples). The thickness of each wall panel can be adjusted according to the proportion as required in practice. Its thickness is directly related to the strength and toughness of the wall panel. The most basic foundation is based on three interwoven layers, as shown in the example. The more stringent the requirements, the more layers there are and the thicker the wall panel becomes.

[0036] In Example 2, the thickness of the lower layer of raw earth wall panel is 20cm. The thickness of the first pressing is 10cm, and the admixtures include 15 parts of active magnesium oxide, 15 parts of cement, 6 parts of fly ash, 15 parts of dry sand, 1.5 parts of sisal of two different lengths, 2 parts of bamboo fiber, 0.15 parts of nanocellulose, and 49 parts of raw earth. The thickness of the second pressing is 10cm, and the admixtures include 20 parts of active magnesium oxide, 15 parts of cement, 6 parts of fly ash, 15 parts of dry sand, 1.5 parts of sisal of two different lengths, 2 parts of bamboo fiber, 0.15 parts of nanocellulose, and 44 parts of raw earth. The upper layer of raw earth wall panels is 30cm thick and is formed by pressing low-magnesium oxide, medium-magnesium oxide, and high-magnesium oxide layers in sequence. The low-magnesium oxide layer is located near the middle functional layer and contains admixtures including 15 parts active magnesium oxide, 15 parts cement, 6 parts fly ash, 15 parts dry sand, 1.5 parts of sisal of two different lengths, 2 parts bamboo fiber, 0.15 parts nanocellulose, and 49 parts raw earth. The medium-magnesium oxide layer contains admixtures including 20 parts active magnesium oxide, 15 parts cement, 6 parts fly ash, 15 parts dry sand, 1.5 parts of sisal of two different lengths, 2 parts bamboo fiber, 0.15 parts nanocellulose, and 44 parts raw earth. The high-magnesium oxide layer contains admixtures including 25 parts active magnesium oxide, 15 parts cement, 6 parts fly ash, 15 parts dry sand, 1.5 parts of sisal of two different lengths, 2 parts bamboo fiber, 0.15 parts nanocellulose, and 39 parts raw earth. The middle layer is the functional layer, which is an asbestos-free calcium silicate board (10cm thick), including calcium silicate powder, aluminum silicate powder, cellulose fiber, and magnesium silicate. The proportions of each component are approximately 54 parts calcium silicate powder, 32 parts aluminum silicate powder, 12 parts cellulose fiber, 4 parts magnesium silicate, and an appropriate amount of water (used to adjust viscosity and hardening process).

[0037] The present invention has been described above by way of example with reference to the accompanying drawings. Obviously, the specific implementation of the present invention is not limited to the above-described manner. Any non-substantial improvements made using the concept and technical solution of the present invention, or the direct application of the concept and technical solution of the present invention to other occasions without modification, are all within the protection scope of the present invention.

Claims

1. A method for forming a carbon-negative, environmentally friendly, multi-layered reinforced rammed earth precast wall panel, characterized in that: The multi-layer reinforced rammed earth precast wall panel includes two layers of composite wall panel (1) and a functional layer disposed between the composite wall panel (1). The composite wall panel (1) includes two layers of rammed earth wall panel (2) and a cellulose bonding layer (3) applied between the two layers of rammed earth wall panel (2). The molding steps of the composite wall panel (1) include: S1, prepare raw material mixtures with three different active magnesium oxide dosages; S2. Soak two types of sisal fibers with lengths of 5-10 mm and 20-30 mm in 1% NaOH solution for 30 minutes, then wash with clean water and air dry. Dry bamboo fibers in an oven at 103℃ for 10 hours until constant weight and set aside. Prepare a 1wt% concentration of 3-glycidyl etheroxypropyltrimethoxysilane ethanol solution as a modifier. Take 100g of bamboo fibers, place the required modifier solution and bamboo fibers in a flask, heat to 60℃ and maintain constant temperature, stir with a magnetic stirrer for 3 hours. Wash the modified bamboo fibers repeatedly with distilled water 3 times, extract to remove excess 3-glycidyl etheroxypropyltrimethoxysilane, and then dry in an oven at 103℃ for 24 hours. After removal, seal in a vacuum bag and store for later use. S3, add water to the mixture of the three raw materials in S1 and stir evenly to form a mixture; S4, add sisal and bamboo fibers of two lengths, 5-10mm and 20-30mm, to the mixture in three batches according to the corresponding amounts and mix well; S5, three different active magnesium oxide content raw material mixtures are filled into molds, manually tamped and loaded, pressed and shaped to form raw earth wall panels (2). S6 is demolded using a demolding machine and immediately placed in a carbonization box for carbonization curing; S7, mix cellulose with water to prepare a solution with a mass fraction of 20% to 30%, let it stand for half an hour and then apply it to the side of the raw earth wall panel (2) with a low active magnesium oxide content. Adhere the raw earth wall panels (2) in pairs to form a composite wall panel (1). Finally, brush a layer of waterproof protective agent on the surface of the composite wall panel (1). The raw earth wall panel (2) is formed by pressing a mixture of raw materials with low active magnesium oxide content and a mixture of raw materials with high active magnesium oxide content in a bottom-up order, consisting of a low magnesium oxide layer, a medium magnesium oxide layer and a high magnesium oxide layer. After demolding, the raw earth wall panel (2) is immediately placed in a carbonization box for carbonization curing. The amount of water added is 20% to 30% of the total mass of the mixture. The setting parameters of the carbonization box are: CO2 concentration 10% to 30%, temperature 20 to 30℃, and humidity 60% to 80%. The high-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 25:15:6:15:0.15:2:1.5:

39. The medium-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 20:15:6:15:0.15:2:1.5:

44. The low-magnesium oxide layer is made by mixing active magnesium oxide, cement, fly ash, dry sand, nanocellulose, bamboo fiber, sisal, and raw soil in a weight ratio of 15:15:6:15:0.15:2:1.5:

49. Two grooves for installing steel reinforcement keel are provided on the high magnesium oxide layer. The grooves are used in conjunction with the I-shaped steel reinforcement keel for the outer layer assembly of the rammed earth wall panel (2).

2. The method for forming a carbon-negative, environmentally friendly, multi-layered reinforced rammed earth precast wall panel according to claim 1, characterized in that: The active magnesium oxide is highly active light-burned magnesium oxide, the cement is 32.5 grade ordinary silicate cement, the fly ash is experimental grade 1 fly ash, the sisal has a length of 5-10 mm, the bamboo fiber is prepared from moso bamboo and green bamboo, and the surface of the bamboo fiber is modified by 3-glycidyl etheroxypropyltrimethoxysilane, the nanocellulose is nanofibrillated cellulose produced based on bleached conifer sulfate pulp, the cellulose used is methylcellulose, the dry sand is natural sand with a particle size of less than 2 mm, and the raw soil has a particle size of less than 2 mm.

3. The method for forming a carbon-negative, environmentally friendly, multi-layered reinforced rammed earth precast wall panel according to claim 1, characterized in that: The active magnesium oxide is highly active light-burned magnesium oxide, the cement is 32.5 grade ordinary silicate cement, the fly ash is experimental grade 1 fly ash, the sisal has a length of 20-30 mm, the bamboo fiber is prepared from moso bamboo and green bamboo, and the surface of the bamboo fiber is modified by 3-glycidyl etheroxypropyltrimethoxysilane, the nanocellulose is nanofibrillated cellulose produced based on bleached conifer sulfate pulp, the cellulose used is methylcellulose, the dry sand is natural sand with a particle size of less than 2 mm, and the raw soil has a particle size of less than 2 mm.

4. The method for forming a carbon-negative, environmentally friendly, multi-layered reinforced rammed earth precast wall panel according to claim 1, characterized in that: The functional layer is a gypsum hollow wall panel.

5. A method for forming a carbon-negative, environmentally friendly, multi-layered reinforced rammed earth precast wall panel according to claim 1, characterized in that: The functional layer is an asbestos-free calcium silicate board.

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