Low carbon stabilized soil matrix and applications

Abstract

The application discloses a low-carbon solidified soil matrix and application. The matrix is made of dredged soil, biochar, slag and gypsum mixed in a specific ratio, and the preferred ratio (T1) is that the mass ratio of the dredged soil, the biochar, the slag and the gypsum is 60:15:10:15. By comparing the mechanical properties and the plant growth effects of different ratios (CK, T1, T2 and T3), it is found that the unconfined compressive strength of the T3 ratio (with the highest content of slag) is the highest (up to more than 3000kPa) after 60 days; however, the T1 ratio (with the highest content of biochar) exhibits the best ecological effect, including significantly promoting the growth of ryegrass, increasing the biomass, optimizing the carbon-nitrogen ratio of soil and enhancing the soil microbial activity, while maintaining sufficient engineering strength (about 1000kPa after 60 days) and excellent dry-wet cycle performance. The application realizes the balance between the mechanical and ecological restoration functions through the collaborative utilization of multi-source solid wastes, and provides an economic, environment-friendly and efficient solution for erosion areas.

Description

Technical Field

[0001] This application belongs to the technical fields of geotechnical engineering and environmental science, solid waste resource utilization, and solid waste recycling, and relates to a method for preparing a low-carbon solidified soil matrix for erosion prevention and ecological restoration using low-carbon materials and industrial by-products. Background Technology

[0002] In many erosion-prone areas, such as riverbanks, hillsides, and coastal regions, traditional erosion control methods have long relied on the use of expensive materials and large-scale land alteration. Techniques such as cement-based stabilizers, synthetic polymers, or concrete structures are not only costly but also lack long-term sustainability. These methods often fail to address the root causes of erosion or effectively achieve ecological restoration. Furthermore, they damage natural landscapes and hinder vegetation growth, which is crucial for long-term soil stability and ecological restoration.

[0003] Current erosion control measures often consume non-renewable resources and generate large amounts of substances that increase carbon emissions. For example, the global cement industry currently emits over 1 billion tons of carbon annually, accounting for approximately 5%-8% of global anthropogenic carbon emissions. In China, the cement industry accounts for about 13% of industrial carbon emissions, further exacerbating the negative environmental impact. Many materials used in traditional erosion control systems are difficult to integrate well with the surrounding ecosystem, and their effects often only last a short time, or even worsen environmental degradation. Furthermore, these materials often require large-scale land modification or the introduction of environmentally unfriendly synthetic substances, thus failing to effectively address long-term erosion problems in vulnerable areas.

[0004] A growing awareness of the environmental impacts of traditional farming practices underscores the urgent need for low-carbon, cost-effective, and durable solutions that not only stabilize soils but also promote ecosystem recovery. Such solutions must effectively address the dual challenges of soil erosion and ecosystem degradation, particularly in erosion-prone areas, necessitating sustainable and long-term remediation measures. Simultaneously, the production of industrial byproducts is increasing, such as slag from steel production, gypsum from flue gas desulfurization, and silt dredged from riverbanks or coastlines. While these materials are abundant, they are often wasted, causing environmental pollution; therefore, more effective recycling or reprocessing methods are urgently needed. The overproduction of these industrial byproducts poses significant challenges to solid waste management, as they are often dumped in landfills or improperly disposed of, exacerbating environmental pollution. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides a low-carbon solidified soil matrix and its application. The method provided in this application, by compounding dredged sediment with biochar, slag, and gypsum in a specified ratio, not only meets engineering application requirements but also promotes plant growth (especially ryegrass) and improves soil structure. This material can be widely used in erosion control and ecological restoration projects for riverbanks, slopes, coastal areas, or dikes. It not only reduces erosion control costs, increases strength, and promotes ecological restoration but also provides a green, economical, efficient, and environmentally friendly solution, avoiding the environmental impact of traditional erosion control materials (such as cement-based materials).

[0006] In a first aspect, this application provides a low-carbon solidified soil substrate, comprising, by weight percentage: Dredged soil 60%-70%, biochar 7.5%-15%, slag 10-25%, gypsum 7.5-15%.

[0007] In one possible implementation, the low-carbon solidified soil substrate comprises, by weight percentage: The composition is 60% dredged soil, 15% biochar, 10% slag, and 15% gypsum.

[0008] In one possible implementation, the biochar is obtained by pyrolysis of agricultural residues or forestry and wood waste under anaerobic or low-oxygen conditions.

[0009] Furthermore, the raw materials for the biochar include one or more of the following: corn stalks, rice stalks, rice husks, and corn cobs.

[0010] In one possible implementation, the low-carbon solidified soil substrate also includes an improver.

[0011] Furthermore, the modifier includes one or more of cement kiln ash and fly ash.

[0012] Secondly, this application provides a method for preparing the low-carbon solidified soil substrate described in the first aspect, comprising: The dredged soil was broken into small particles; According to the stated mass percentages, the treated dredged soil, biochar, slag and gypsum were dry-mixed and stirred evenly. Add an appropriate amount of water and mix thoroughly to form a homogeneous mixture; The mixture is then shaped and cured to obtain the final product.

[0013] In one possible implementation, the maintenance conditions are: temperature 18-22°C, relative humidity not less than 95%.

[0014] Thirdly, this application provides the application of the low-carbon solidified soil substrate described in the first aspect in the preparation of erosion control and ecological restoration engineering materials for riverbanks, slopes, coastal areas or dikes.

[0015] In one possible implementation, the ecological restoration engineering materials include engineering materials that promote the production of soil microbial enzymes and the growth of grass.

[0016] The beneficial effects of this application are as follows: (1) The method provided in this application utilizes multi-source solid waste (dredged soil, gypsum, biochar, slag) to transform industrial solid waste into a solution that meets engineering strength requirements while also taking into account ecological restoration effects, thereby achieving a balance between the mechanical properties and ecological functions of the substrate. This method not only improves the resource utilization rate of solid waste, facilitates cost control, energy conservation and emission reduction, and environmental protection, but also significantly enhances ecological benefits.

[0017] (2) Compared with traditional erosion control materials (such as cement-based materials), the low-carbon solidified soil substrate provided in this application makes full use of multi-source industrial solid waste, which not only avoids the secondary pollution to the environment caused by traditional erosion control materials, but also further promotes ecological restoration and can improve soil structure, such as increasing soil biomass, optimizing soil carbon-nitrogen ratio and enhancing soil microbial activity, which has a positive impact on the environment.

[0018] (3) The process for preparing the substrate provided in this application is simple and conducive to large-scale production and promotion. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the low-carbon solidified soil matrix preparation process provided in the embodiments of this application; Figure 2 The solidification and compression test of the low-carbon solidified soil matrix provided in the embodiments of this application; Figure 3 Plant growth of low-carbon solidified soil matrix with different formulations provided in the embodiments of this application at 10 days, 22 days and 35 days; Figure 4 UCS test results of low-carbon solidified soil matrix with different formulations provided in the embodiments of this application at 14 days, 28 days and 60 days; Figure 5 XRD patterns of low-carbon solidified soil matrices with different formulations provided in the embodiments of this application; Figure 6 Microstructure diagrams and elemental composition of low-carbon solidified soil matrices under different formulations provided in the embodiments of this application; Figure 7 Results of 0, 2, 4, 7, 10 and 12 wet-dry cycle strength tests on low-carbon solidified soil matrices with different formulations provided in the embodiments of this application; Figure 8 The effects of low-carbon solidified soil matrix with different formulations provided in the embodiments of this application on the dynamics of plants (right) and soil nutrients (left); Figure 9 The effects of different formulations of low-carbon solidified soil matrix provided in the embodiments of this application on the chlorophyll a and b content of plants; Figure 10 The effects of different formulations of low-carbon solidified soil matrix provided in the embodiments of this application on soil electrical conductivity and microbial activity; Figure 11 This is a schematic diagram illustrating the interaction between the substrate and the plant as provided in an embodiment of this application. Detailed Implementation

[0020] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0021] In the description of this application, the term "for example" is used to mean "used as an example, illustration, or description." Any embodiment described as "for example" in this application is not necessarily to be construed as being more preferred or advantageous than other embodiments. The following description is provided to enable any person skilled in the art to make and use this application. Details are set forth in the following description for purposes of explanation. It should be understood that those skilled in the art will recognize that this application can be made without using these specific details. In other instances, well-known structures and processes will not be described in detail to avoid unnecessarily obscuring the description of this application. Therefore, this application is not intended to be limited to the embodiments shown, but is consistent with the broadest scope of the principles and features disclosed in this application.

[0022] The excessive production of industrial by-products poses a significant challenge to solid waste treatment. These by-products are often dumped in landfills or improperly disposed of, exacerbating environmental pollution. Furthermore, existing soil matrix materials have poor vegetation-growth properties and offer extremely limited ecological restoration benefits to the soil.

[0023] In view of this, this application provides a low-carbon solidified soil matrix and its application.

[0024] A low-carbon solidified soil substrate, comprising, by weight percentage: Dredged soil 60%-70%, biochar 7.5%-15%, slag 10-25%, gypsum 7.5-15%.

[0025] In one possible implementation, the low-carbon solidified soil substrate comprises, by weight percentage: The composition is 60% dredged soil, 15% biochar, 10% slag, and 15% gypsum.

[0026] In one possible implementation, the biochar is obtained by pyrolysis of agricultural residues or forestry and wood waste under anaerobic or low-oxygen conditions.

[0027] Furthermore, the raw materials for the biochar include one or more of the following: corn stalks, rice stalks, rice husks, corn cobs, and fruit shells.

[0028] In one possible implementation, the slag is industrial slag, an industrial byproduct prepared by blast furnace ironmaking through "molten slag → water quenching and granulation → drying and grinding", and is officially called finely ground blast furnace slag (GBFS).

[0029] In one possible implementation, the low-carbon solidified soil substrate also includes an improver.

[0030] Furthermore, the modifier includes one or more of cement kiln ash and fly ash.

[0031] The above describes the low-carbon solidified soil matrix; the preparation method of this matrix is ​​described below.

[0032] A method for preparing a low-carbon solidified soil substrate includes: S101. The dredged soil is crushed into small particles; S102. According to the stated mass percentage, the treated dredged soil, biochar, slag and gypsum are dry-mixed and stirred evenly. S103. Add an appropriate amount of water and wet mix to form a uniform mixture; S104. The mixture is shaped and cured to obtain the final product.

[0033] In one possible implementation, the particle size is less than 2 mm.

[0034] In one possible implementation, the maintenance conditions are: temperature 18-22°C, relative humidity not less than 95%.

[0035] Furthermore, the temperature for the curing process is 18-22℃.

[0036] The technical solution of this application will be further described below with reference to more specific embodiments, but it is not intended to limit the scope of this application.

[0037] The experimental materials included dredged soil, biochar, slag, and gypsum.

[0038] The dredged soil was taken from the riverbank excavation site, air-dried at room temperature, and sieved to less than 2 mm. It had a moisture content of 5% and its main components were SiO2 and Al2O3. The dredged soil used in this embodiment originated from Nanjing, Jiangsu Province.

[0039] Biochar is produced from agricultural waste. After impurities are removed, the waste is crushed and sieved, and then dried to constant weight at 60-105℃. It is then placed in a controlled furnace and subjected to oxygen-limited pyrolysis carbonization in a low-oxygen environment created by purging nitrogen. After the product cools to room temperature, it is ground, sieved, washed until neutral, and dried again to obtain the finished biochar product. Before use, the biochar is sieved to a size less than 3mm and homogenized. In the embodiments of this application, the biochar is a mixture of corn stalks, wheat stalks, and rice stalks.

[0040] Blast furnace slag is an industrial byproduct of blast furnace ironmaking. It is prepared by "molten slag → water quenching and granulation → drying and grinding". Its main components are SiO2, Al2O3, Fe2O3 and CaO. It mainly comes from the solid residues generated by coal combustion in facilities such as coal-fired power plants, industrial boilers, thermal power plants and heating furnaces.

[0041] Gypsum, mainly raw gypsum (CaSO4·2H2O), is made from natural gypsum ore or industrial by-product gypsum through physical processing such as crushing, impurity removal, low-temperature drying, and grinding. Its main sources are gypsum ore mining and processing or by-products from industrial processes such as flue gas desulfurization, phosphorus chemical industry, and titanium dioxide production.

[0042] The main physicochemical properties of the raw materials used in the embodiments of this application are shown in Table 1.

[0043] Table 1 Physicochemical properties of each raw material in the examples

[0044] Note: % in Table 1 represents mass percentage.

[0045] The experimental grouping and mixing scheme are shown in Table 2.

[0046] Table 2 Test Protocol

[0047] Note: % in Table 2 represents mass percentage.

[0048] See Figure 1 The method for preparing low-carbon solidified soil matrix provided in this application includes the following steps: (1) Preparation of dredged soil. In order to meet the test requirements, the excavated dredged soil needs to be mechanically crushed. The particle size of the crushed dredged soil should be less than 2 mm.

[0049] (2) Matrix preparation. According to the experimental plan, the crushed dredged soil, biochar, slag and gypsum were placed in a mixer and mixed thoroughly, and then poured into a 50mm×50mm mold.

[0050] (3) Matrix curing. The prepared samples were cured at a temperature of 18-22°C and a humidity of ≥95% for 14 days, 28 days and 60 days respectively.

[0051] The test items for the sample include: (1) Matrix strength test. After curing, the unconfined compressive strength test and wet-dry cycle test were carried out. The unconfined compressive strength test (UCS) was carried out in accordance with the standard for geotechnical testing methods (CB / T 50123-2019).

[0052] (2) Substrate cultivation experiment. Perennial ryegrass (Lolium perenne) was selected at 25 g / m². 2 The seeding rate was determined by sowing the seeds on substrate that had been cured for 7 days. The substrate was placed in a plastic box and observed for 35 days under controlled humidity conditions (soil moisture content 70-80%). Throughout the growth period, the germination rate, plant height, chlorophyll content (SPAD value), carbon and nitrogen content, and biomass accumulation of perennial ryegrass were recorded.

[0053] Example 1: Preparation of low-carbon solidified soil matrix for erosion control and ecological restoration and the effects of different treatment schemes on solidification effect.

[0054] The preparation of low-carbon solidified soil matrix is ​​carried out according to the process in steps (1), (2), and (3), as detailed in the following steps: Figure 1 As shown. The prepared samples were tested according to implementation step (4). Unconfined compressive strength tests were conducted at 14d, 28d, and 60d respectively. It was found that T3 had a better curing effect than T1 and T2. After 60 days of curing, T3 reached 3057.23 kPa, as shown in the figure. Figure 4 As shown. Through analysis Figure 5The XRD patterns show that the crystallinity of the matrix gradually increases from CK to T3, and the diffraction peaks become more pronounced. CK mainly contains kaolinite phase, indicating that kaolinite is the main mineral in the dredged soil. The T1 group shows gypsum, calcite, and calcium magnesium olivine crystals, indicating that the kaolinite crystalline phase in the T1 group transforms into a coexistence of gypsum, calcite, and calcium magnesium olivine crystalline phases. This suggests that the strength of T1 is mainly contributed by calcium magnesium olivine as the key strength-contributing crystalline phase, while calcite acts as a physical filler, which also explains the lower strength of T1. In contrast, T2 and T3 show a significant increase in dicalcium silicate crystallinity compared to T1. Dicalcium silicate can further undergo hydration to form hydrated calcium silicate (CSH gel), which greatly improves the strength of T2 and T3. The diffraction peaks of T3 are the clearest and most pronounced, which explains its highest strength. These changes all indicate that inorganic phases gradually integrate into the matrix, greatly enhancing its strength and stability, especially evident in T2 and T3.

[0055] Referring to Table 3, elemental analysis was used to detect the content of elements such as carbon (C), oxygen (O), silicon (Si), aluminum (Al), and iron (Fe) in the matrices of different groups (CK, T1, T2, T3). Images taken at magnifications of 5 and 10 μm further revealed the effects of different processing methods on the material surface. Figure 6 As shown, the surface morphology and elemental composition of the matrix underwent significant evolution from CK to T3. The CK group exhibited a relatively dense morphology with fine pores and granular structures, dominated by kaolinite, and a high C content, indicating the presence of organic matter. The T1 group showed a rougher surface morphology, with the emergence of numerous flocculent and needle-like structures, resulting in a looser surface. This suggests that increased biochar content leads to a more porous surface. Simultaneously, the contents of C and Al decreased significantly, while O, Si, Fe, and Ca increased significantly, indicating that primary minerals such as kaolinite began to decompose in large quantities, generating new phases such as gypsum, calcite, and calcium magnesium olivine, further validating the XRD analysis. The changes in the surface of the T2 and T3 groups were even more pronounced. The T2 group also exhibited a flocculent structure, but its density was somewhat restored compared to T1. The T3 group showed a relatively uniform surface morphology with a distinct granular texture, indicating that cementitious products were generated in the T2 and T3 groups to fill the pores between soil particles. XRD pattern analysis shows that during the curing processes of T2 and T3, with the formation of dicalcium silicate, OH... - As the concentration gradually increases, it can react with free Al in the matrix. 3+ Combined with [Al(OH)6] 3- SO4 in gypsum 2- It can be further combined with [Al(OH)6] 3- Free Ca 2+The reaction produces calcium vanadate (AFt), while SiO2 in the slag is converted into [SiO(OH)3] under alkaline conditions. - (Silicate ions), thus reacting with free Ca 2+ After undergoing the aforementioned strengthening and curing processes, the matrix strength of groups T2 and T3 was significantly improved, especially group T3, which exhibited the strongest mineralization and densest structure, resulting in excellent mechanical properties. However, based on... Figure 3 It can be seen that in group T3, the plants can grow normally on day 10, but a large number of plants wither on day 22, indicating that its ecological effect is poor. The reason is that its dense structure makes the plant roots unable to breathe and thus die.

[0056] Table 3. Elemental composition of dredged soil matrix and treatment group

[0057] Example 2: Preparation of low-carbon solidified soil matrix for erosion control and ecological restoration and the effects of different treatment schemes on dry-wet cycle.

[0058] The preparation of low-carbon solidified soil matrix is ​​carried out according to the process in steps (1), (2), and (3), as detailed in the following steps: Figure 1 As shown. The prepared samples were tested according to the sample testing items. By conducting 0, 2, 4, 7, 10, and 12 wet-dry cycle tests on the 28-day samples, it was found that the substrates with different treatments maintained high strength and high durability after wet-dry cycles. The results are as follows. Figure 7 As shown.

[0059] For the control group (CK), the matrix consisted entirely of dredged soil. In the 0th wet-dry cycle, the matrix strength was 95.13 kPa, gradually decreasing in subsequent cycles, reaching 22.17 kPa by the 12th cycle. This indicates that the strength of untreated dredged soil decreased rapidly during wet-dry cycles, suggesting that mechanical strength is primarily influenced by the inherent properties of the dredged soil itself.

[0060] The initial strength of the matrix in group T1 was 825.24 kPa, which gradually decreased in subsequent cycles, reaching 718.94 kPa by the 12th wet-dry cycle. The initial strength of group T2 was 1423.16 kPa, which decreased to 1137.28 kPa by the 12th wet-dry cycle. For the matrix in group T3, the strength change trend after wet-dry cycles was similar to that of group T2, but the rate of strength decrease was slightly slower. In the 0th wet-dry cycle, the initial strength of the matrix was 2368.42 kPa, which decreased to 2118.24 kPa by the 12th wet-dry cycle.

[0061] Overall, the matrix after different treatments can effectively enhance mechanical strength and stability, combined with Figure 6 Analysis revealed that the addition of biochar, slag, and gypsum significantly altered the microstructure and elemental distribution of the dredged soil. Particularly in groups T2 and T3, the higher slag content resulted in a more ordered and stable matrix structure, with increased concentrations of elements such as Ca, Fe, and Ti, thereby enhancing the matrix's mechanical strength and stability. Gypsum, on the other hand, improved the overall stability of the matrix, making it more resistant to strength changes under wet-dry cycles.

[0062] Example 3: Preparation of low-carbon solidified soil matrix for erosion control and ecological restoration and the effects of different treatment schemes on plant and soil nutrient dynamics. The low-carbon solidified soil matrix was prepared according to the procedures in steps (1) and (2). After preparation, tests were conducted according to the sample testing items. Figure 3 It was found that the plants in group T1 grew well; therefore, the carbon and nitrogen contents of the plants and soil in both CK and T1 groups were analyzed. Figure 8 As shown, the experimental results indicate that the carbon and nitrogen content in the plant (T1 group) was significantly higher than that in the untreated group (CK), while the carbon-nitrogen ratio in the T1 group was lower than that in the untreated group (CK), indicating that the carbon and nitrogen ratio in the plants in the T1 group was more balanced. Conversely, the carbon and nitrogen content in the soil (Soil) was significantly lower in the T1 group than that in the untreated group (CK), suggesting that the T1 group may affect the carbon and nitrogen cycling process in the soil, making the nutrient cycling in the soil more efficient and further promoting plant growth.

[0063] Example 4: Preparation of low-carbon solidified soil matrix for erosion control and ecological restoration and the effects of different treatment schemes on chlorophyll a and chlorophyll b in plants. The low-carbon solidified soil matrix was prepared according to the procedures in steps (1) and (2). After preparation, tests were conducted according to the sample testing items. To better demonstrate the plant growth, the chlorophyll content of perennial ryegrass in CK and T1 samples was detected. Figure 9 As shown in the results, the average chlorophyll a content of plants in group T1 was significantly higher than that in the untreated group (CK), with an average content of 9.43 µg / g in group T1 and 5.73 µg / g in group CK. This indicates that group T1 can promote the production of chlorophyll a in plants. Similarly, the average chlorophyll b content of plants in group T1 was also significantly higher than that in group CK, with an average content of 5.36 µg / g in group T1 and 3.53 µg / g in group CK. Group T1 significantly increased the chlorophyll b content in plants, suggesting that this group may have a positive effect on chloroplast development or pigment synthesis.

[0064] Example 5: Preparation of low-carbon solidified soil matrix for erosion control and ecological restoration and the effects of different treatment schemes on soil electrical conductivity and microbial activity The low-carbon solidified soil matrix was prepared according to the procedures in steps (1) and (2). After preparation, the samples were tested according to the test items. Figure 10 The results show that group T1 had a significant impact on various biological and chemical properties of the soil, specifically in terms of electrical conductivity ( Figure 10 (above), β-glucosidase activity ( Figure 10 (in the middle) and urease activity ( Figure 10 (The changes below)

[0065] The decrease in electrical conductivity in group T1 indicates an improvement in soil salinity, which is beneficial to improving soil health and making the soil more conducive to plant root growth and microbial activity. The increase in β-glucosidase and urease activity indicates that group T1 not only promoted the production of microbial enzymes in the soil, but also enhanced key processes of soil organic matter decomposition and nitrogen cycling.

[0066] These results further demonstrate the potential role of T1 in improving soil biological processes and reducing soil salinity, both of which are important for enhancing soil fertility and promoting soil microbial activity.

[0067] As can be seen from the above examples, the mechanical properties of groups T1, T2, and T3 are all higher than those of the untreated group (CK). Group T3 has the highest strength (reaching over 3000 kPa in 60 days), but its ecological effect is almost zero. T1, while meeting the strength requirements, has a better ecological effect than the untreated group (CK).

[0068] Based on the experimental results in Examples 1, 2, 3, 4, and 5 above, the unconfined compressive strength of group T1 after 60 days is close to 1000 kPa, which is 7-8 times higher than that of the untreated group. Simultaneously, the substrate treated with T1 exhibits good durability, meeting engineering requirements. Furthermore, the plant growth in group T1 is basically similar to that in the untreated group (CK). The plant carbon-nitrogen ratio, chlorophyll content, soil carbon-nitrogen ratio, electrical conductivity, and microbial activity in group T1 are all superior to those in the untreated group (CK), indicating that group T1 simultaneously considers both mechanical and ecological performance. Therefore, the optimal formulation (T1) of the low-carbon solidified soil substrate provided in this application is as follows: Dredged soil: 60% Biochar: 15% Slag: 10% Gypsum: 15% This formulation, by adjusting the proportions of each component, ensures that the final sample maintains suitable pore density and good mechanical properties while also achieving excellent plant growth performance. Specifically, biochar can create a favorable growth environment for plants by improving soil physical structure, regulating the chemical environment, and activating biological activity. This application controls the biochar content to 15%, which reduces the pore density of the sample to a certain extent. Relatively low pore density is beneficial for plant root growth, thus improving plant growth performance; conversely, lower biochar content diminishes these effects, leading to a significant decline in plant growth performance. This application uses 15% gypsum as an activation agent, reacting with calcium-based raw materials to generate hydrated products such as ettringite (AFt) and CSH gel, effectively filling soil pores and enhancing soil strength, providing a stable mechanical basis for plant root anchorage. Simultaneously, the Ca released from gypsum... 2+ Biochar participates in soil cation exchange, promotes aggregate formation, and improves the acid-base environment for microbial survival by moderately reducing the pH value of alkaline soil (<8). Based on this, this application controls the content of both biochar and gypsum to 15%, resulting in a significant synergistic effect. On the one hand, the porous structure of biochar constructs a reservoir for nutrients and water, which, together with the soil aggregates induced by gypsum, optimizes the soil's aeration and water retention capacity, providing a suitable physical environment for the synthesis and catalysis of soil enzymes. On the other hand, the alkaline buffering capacity of biochar and the pH-regulating effect of gypsum counterbalance each other, stabilizing the soil's acid-base environment and significantly enhancing the activity of soil enzymes such as urease and phosphatase. Furthermore, the sulfur nutrients provided by gypsum and the calcium adsorbed by the functional groups on the surface of biochar form a slow-release nutrient system, continuously supplying plant roots and microbial metabolism, ultimately achieving a comprehensive balance between soil strength and high-enzyme-activity vegetation performance.

[0069] This application successfully developed a substrate that is both robust and environmentally friendly by using materials such as dredged sediments, biochar, slag, and gypsum. This substrate is particularly helpful in improving soil quality and promoting vegetation growth, which are key factors in achieving ecological restoration. Furthermore, utilizing industrial byproducts not only enhances the performance of the substrate but also reduces the environmental impact of waste materials.

[0070] The substrate provided in this application not only enhances soil stability but also helps promote the development of sustainable infrastructure. It can effectively address the urgent need for environmentally friendly and economically viable solutions in erosion-prone areas (such as riverbanks, hillsides, and coastal areas) because traditional methods often fail to achieve long-term stability or deliver significant ecological benefits.

[0071] This application also provides the application of the substrate in the preparation of erosion control and ecological restoration engineering materials for riverbanks, slopes, coastal areas or dikes.

[0072] In one possible implementation, the ecological restoration engineering materials include engineering materials that promote the production of soil microbial enzymes and the growth of grass.

[0073] Understandably, the substrate can promote grass growth and improve soil structure, such as increasing soil biomass, optimizing soil carbon-nitrogen ratio, and enhancing soil microbial activity.

[0074] Specifically, the soil microbial enzymes include β-glucosidase and urease; the planted grass includes ryegrass (Lolium perenne).

[0075] Figure 11 A schematic diagram illustrating the interaction between the substrate and the plant provided in an embodiment of this application is shown.

[0076] In summary, the embodiments of this application provide an economical and environmentally friendly innovative solution that effectively prevents erosion and makes reasonable use of industrial by-products, making it highly suitable for erosion control and ecological restoration projects on riverbanks, slopes, coastal areas, or dikes. The matrix provided in these embodiments not only reduces the environmental impact of excess industrial solid waste but also offers a sustainable alternative to traditional erosion control measures. The matrix prepared from these materials can withstand the long-term effects of natural environmental conditions such as wet-dry cycles, rainfall, and runoff, making it an ideal solution for long-term soil stabilization and ecological restoration in vulnerable areas.

[0077] The above description is merely a preferred embodiment of this application, but the scope of protection of this application is not limited thereto. Any modifications, equivalent substitutions, and improvements made by those skilled in the art within the scope of the technology disclosed in this application should be included within the scope of protection of this application.

Claims

1. A low-carbon solidified soil substrate, characterized in that, By weight percentage, including: Dredged soil 60%-70%, biochar 7.5%-15%, slag 10-25%, gypsum 7.5-15%.

2. The low-carbon solidified soil substrate according to claim 1, characterized in that, The low-carbon solidified soil substrate comprises, by weight percentage: The composition is 60% dredged soil, 15% biochar, 10% slag, and 15% gypsum.

3. The low-carbon solidified soil substrate according to claim 1, characterized in that, The biochar is obtained by pyrolysis of agricultural residues or forestry and wood waste under anaerobic or low-oxygen conditions.

4. The low-carbon solidified soil substrate according to claim 3, characterized in that, The raw materials for the biochar include one or more of the following: corn stalks, rice stalks, rice husks, and corn cobs.

5. The low-carbon solidified soil substrate according to any one of claims 1-4, characterized in that, The low-carbon solidified soil substrate also includes an improver.

6. The low-carbon solidified soil substrate according to claim 5, characterized in that, The modifier includes one or more of cement kiln ash and fly ash.

7. A method for preparing a low-carbon solidified soil substrate according to any one of claims 1-6, characterized in that, include: The dredged soil was broken into small particles; According to the stated mass percentages, the treated dredged soil, biochar, slag and gypsum were dry-mixed and stirred evenly. Add an appropriate amount of water and mix thoroughly to form a homogeneous mixture; The mixture is then shaped and cured to obtain the final product.

8. The preparation method according to claim 7, characterized in that, The maintenance conditions are: temperature 18-22℃, relative humidity not less than 95%.

9. The application of the low-carbon solidified soil substrate according to any one of claims 1-6 in the preparation of erosion control and ecological restoration engineering materials for riverbanks, slopes, coastal areas or dikes.

10. The application according to claim 9, characterized in that, The ecological restoration engineering materials include engineering materials that promote the production of soil microbial enzymes and the growth of grass.

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