Restoration material and method for wind erosion damage in rammed earth ruins

Abstract

The present invention relates to the field of cultural heritage protection technology, and specifically to a repair material and repair method for wind erosion diseases in rammed earth sites. The repair material includes a mineralized bacterial solution and a cementing nutrient solution; the mineralized bacterial solution contains a living Bacillus pasteurianus strain and a liquid culture medium, and the liquid culture medium contains sucrose as a carbon source and yeast powder as a nitrogen source; the cementing nutrient solution is an aqueous solution containing water-soluble calcium, wood calcium, corn cob powder and urea; the corn cob powder is corn cob powder activated by potassium carbonate; the mineralized bacterial solution and the cementing nutrient solution are stored separately, and the mineralized bacterial solution and the cementing nutrient solution are mixed and formulated before use to obtain a repair material for wind erosion diseases in rammed earth sites. After the repair material of the present invention repairs the rammed earth site, it can effectively prevent the disease from further expanding and deteriorating, and can not only preserve the original appearance of the rammed earth site, but also avoid the problem of loss of historical beauty caused by traditional repair methods.

Description

Technical Field

[0001] The present invention relates to the technical field of cultural heritage protection, and in particular to a material and method for repairing wind erosion damage at rammed earth sites based on microbial mineralization. Background Art

[0002] As a World Heritage Site, rammed earth ruins are important symbols of human history and precious cultural heritage. However, after centuries of weathering and exposure to natural factors, the earthen walls have long been eroded by weathering and wind erosion. This has led to serious damage to the soil, including surface peeling, crack expansion, the formation and intensification of holes, and even localized collapse. These problems not only reduce the structural stability of the rammed earth ruins and increase the risk of further damage, but also threaten their unique historical value and cultural significance.

[0003] Traditional restoration methods often address these issues by filling or covering damaged areas to restore surface integrity. Common restoration materials typically include highly viscous and strong grouting materials, including cement clinker, gypsum, lime, and ultrafine slag. While this approach can improve the appearance in the short term, due to significant differences in the physical and chemical properties of the restoration materials and the original soil, such methods often destroy the original texture and appearance of rammed earth sites, altering the color and characteristics of the original earthen artifacts and failing to reproduce their historical imprint. The restoration of rammed earth sites also poses the problem of water erosion caused by excessive use of restoration solutions. Furthermore, excessive restoration, or even filling all damaged areas, can easily undermine the cultural authenticity and aesthetic value of the artifacts, failing to restore them to their original state. Many existing restoration materials lack compatibility with the original soil of rammed earth sites, resulting in poor durability and prone to re-fracture or deterioration under the influence of the natural environment, causing secondary damage. Furthermore, some restoration materials incorporate rubber latex to increase toughness and viscosity, which is less biodegradable and poses a certain risk of environmental pollution. Summary of the Invention

[0004] (1) Technical issues to be resolved

[0005] In view of the above-mentioned shortcomings and deficiencies of the prior art, the present invention provides a repair material and a repair method for wind erosion diseases of rammed earth sites. After the diseased parts of the rammed earth sites are repaired by the method of the present invention, a mineralized crust with breathability, no color difference, and wind erosion resistance can be formed, thereby effectively repairing the disease and preventing it from continuing to expand. It can not only preserve the original appearance of the earth site, but also have good environmental protection and compatibility with the original soil, solving the technical problems of the existing repair methods such as loss of historical beauty, destruction of the original texture and style of the rammed earth site, poor compatibility, low durability, and environmental pollution.

[0006] (2) Technical solution

[0007] In a first aspect, the present invention provides a repair material for wind erosion damage in rammed earth ruins, which comprises a mineralizing bacterial solution and a cementing nutrient solution;

[0008] The mineralized bacterial liquid contains a living Bacillus pasteurianus strain and a liquid culture medium, wherein the liquid culture medium contains sucrose as a carbon source and yeast powder as a nitrogen source; the cementing nutrient solution is an aqueous solution containing water-soluble calcium, wood calcium, corn cob powder and urea; and the corn cob powder is corn cob powder activated with potassium carbonate;

[0009] The mineralizing bacterial solution and the cementing nutrient solution are stored separately, and are mixed and formulated before use to obtain a repair material for wind erosion damage at rammed earth ruins.

[0010] According to a preferred embodiment of the present invention, the Bacillus pasteurianus strain in the mineralized bacterial solution is in a logarithmic growth phase, preferably with an optical density OD600 of 1 to 2. The pH of the mineralized bacterial solution is slightly acidic to slightly alkaline (i.e., pH 6 to 8), preferably 6.5 to 7.5.

[0011] According to a preferred embodiment of the present invention, the sucrose concentration in the mineralized bacterial solution is 10-15 g / L, and the yeast powder concentration is 15-20 g / L.

[0012] According to a preferred embodiment of the present invention, the molar concentration of urea in the cementing nutrient solution is 0.5-1 times the concentration of calcium ions in water-soluble calcium; the molar concentration of urea is 0.05-1.0 mol / L; and the amount of wood calcium added to the cementing nutrient solution is 0.5-3wt%.

[0013] According to a preferred embodiment of the present invention, the water-soluble calcium in the cementitious nutrient solution is at least one of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate, preferably calcium chloride. The water-soluble calcium provides the calcium ions required for mineralization, while the wood calcium is used for coloring, making the repaired area more similar to the original color of the rammed earth ruins, achieving a restoration effect that resembles the original.

[0014] Calcium chloride is highly soluble, at approximately 74 g / 100 mL of water at 20°C. It rapidly provides free calcium ions and has a neutral pH, minimizing interference with microbial activity (e.g., Bacillus pasteurianus). However, its chloride ions may corrode metal structures (e.g., nails found in ruins). Calcium nitrate, with a solubility of approximately 121 g / 100 mL, rapidly provides free calcium ions. Since it lacks chloride ions, it is suitable for the restoration of ruins containing metal components. However, its nitrate ions may serve as a nitrogen source for microorganisms, potentially promoting algal growth and attachment in humid environments. This, however, provides the nutrients necessary for long-term microbial calcification. Calcium acetate, with a solubility of approximately 34 g / 100 mL, is a mild, organic, water-soluble calcium salt. Its decomposition products are carbon dioxide and water, making it highly environmentally compatible. Calcium acetate is more suitable for restorations requiring slower mineralization rates and pH-sensitive conditions (e.g., murals). Calcium lactate has a low solubility (5g / 100mL) and does not provide a large amount of free calcium ions. However, it is highly biodegradable and has a slow mineralization rate. It requires long-term bioactivity and is suitable for areas with strict biotoxicity requirements. In practical applications, one or more of the four water-soluble calcium sources listed above can be selected based on the specific composition of the rammed earth site. For example, a combination of calcium chloride and calcium nitrate is recommended for efficient mineralization. Organic calcium salts can be used for sensitive remediation sites requiring greater ecological compatibility. Combining calcium chloride with calcium lactate offers a balanced approach to mineralization speed and ecological safety.

[0015] Preferably, the aqueous calcium solution is compound calcium, which is a combination of calcium chloride and calcium lactate. Calcium chloride can quickly release calcium ions to accelerate the initial mineralization rate, while calcium lactate slowly releases calcium ions to extend the mineralization cycle. Calcium lactate can also provide the carbon source required by microorganisms. In the compound calcium, the molar ratio of calcium chloride to calcium lactate is 2-3:2.

[0016] According to a preferred embodiment of the present invention, the concentration of corncob powder in the cementitious nutrient solution is 1-4wt%, and the corncob powder has a particle size of 0.05-0.25mm. Preferably, the corncob powder is activated with potassium carbonate. Activating the corncob powder with potassium carbonate increases its porosity, thereby improving its CaCO3 loading rate and loading capacity.

[0017] According to a preferred embodiment of the present invention, 1-3wt% of rice husk ash mesoporous silica (pore size of 10-30nm) is further added to the cementitious nutrient solution, with a specific surface area of 500-1000m² / g and a particle size of 0.1–1μm (obtained by directly calcining rice husk ash at high temperature). The main functions of rice husk ash mesoporous silica are: ① Rice husk ash mesoporous silica can load urea or calcium salts in the cementitious nutrient solution. Due to its chemical inertness, it is not easy to react with rammed earth components (such as clay minerals) and has an extremely low expansion coefficient, thus avoiding secondary damage to the site structure. ② Rice husk ash mesoporous silica can penetrate into the micro-cracks of rammed earth (0.1–10μm), and synergistically fill the pores with calcium carbonate precipitation to reduce the risk of wind erosion. ③ Rice husk ash mesoporous silica can adsorb SO2 and NO in the air x , slowing chemical weathering of the site. ④ Reducing the instantaneous release of ammonia, minimizing environmental disturbances to the rammed earth site. ⑤ Using rice husk ash mesoporous silica with a pore size of 10-30nm, it can block microcracks while allowing the repaired area to remain breathable.

[0018] Preferably, a silane coupling agent can be grafted onto the surface of the rice husk ash mesoporous silica to enhance the bonding strength with the rammed earth matrix.

[0019] Preferably, corn cob powder can also be added to the mineralized bacterial solution as a carrier and nutrient for the bacteria.

[0020] In a second aspect, the present invention provides a method for repairing wind erosion damage in rammed earth ruins, comprising the following steps:

[0021] Repair construction is performed using the repair material described in any of the above embodiments. A mineralizing bacterial solution and a cementing nutrient solution are mixed in a volume ratio of 1:1-1:2 to form a biomineralization precursor solution. Repair construction is performed within 5-40 minutes of obtaining the biomineralization precursor solution. The biomineralization precursor solution is applied to the damaged area of the rammed earth ruins three times a day, with at least 3 hours between each application. Each application day constitutes one cycle. After 3-6 days of continuous treatment in this manner, natural curing is performed. Preferably, the damaged area of the rammed earth ruins includes holes and cracks.

[0022] (3) Beneficial effects

[0023] 1. The present invention provides a repair material for wind erosion damage in rammed earth sites, which can be used to repair rammed earth sites that are easily eroded by wind and water. A bacterial liquid with mineralization ability and a cementing nutrient solution with specific components are combined to obtain a biomineralization precursor solution. The biomineralization precursor solution is applied to the diseased area. The flocs generated by rapid induction can be well adsorbed on the diseased area, forming a mineralized crust with good air permeability, no color difference, and wind erosion resistance, thereby effectively repairing the disease and preventing it from continuing to expand. After the repair material of the present invention repairs the rammed earth site, it can not only preserve the original appearance of the rammed earth site and avoid the problem of loss of historical beauty caused by traditional repair methods, but also effectively prevent the disease from further expansion and deterioration after repairing local hole diseases and crack diseases. The repaired area does not change the original soil color, and maintains the original historical beauty.

[0024] 2. Adding corncob powder to the cementing nutrient solution increases the mineralization reaction rate by 5-20%, rapidly forming a protective mineralized crust. Activation with potassium carbonate increases the porosity of the corncob powder, thereby improving its CaCO3 loading rate and capacity. The proportion of wood calcium is adjusted based on the color of the original soil at the rammed earth site, until it matches the original soil to ensure color consistency after restoration (color difference ΔE < 5). In practice, a combination of organic and inorganic calcium is used to adjust the release rate of free calcium ions, thereby adjusting the mineralization rate and ecological safety based on the restoration target. Rice husk ash mesoporous silica synergistically fills pores with calcium carbonate precipitation, reducing the risk of wind erosion and slowing chemical weathering at the site. It is suitable for the detailed restoration of high-value sites, such as reinforcing microcracks in mural layers and carved details. Grafting with a coupling agent enhances adhesion to the rammed earth matrix and prevents particle migration or agglomeration. Rice husk ash mesoporous silica is off-white or light gray and synergizes with wood calcium during application to achieve color matching.

[0025] The components of the repair material of the present invention are environmentally friendly and contain no chemical synthetic materials. They are well compatible with the original soil, ensuring that the air permeability and environmental adaptability of the rammed earth site are maintained during the repair process, achieving the dual goals of cultural heritage protection and environmentally friendly restoration. It is particularly suitable for the control and repair of hole diseases and crack diseases in rammed earth sites, and has the advantages of environmental protection, durability and avoidance of secondary damage. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 This is a flow chart for repairing wind erosion damage in rammed earth ruins according to the present invention.

[0027] Figure 2 Pictures of indoor specimens from the rammed earth site selected for the experiment.

[0028] Figure 3 This is a data chart of the mineralization rate of the rammed earth site wind erosion damage repair material of the present invention.

[0029] Figure 4 This is a color difference comparison chart of the specimens repaired with different repair methods.

[0030] Figure 5 These are the wind erosion resistance test results of the specimens repaired with the repair material of the present invention.

[0031] Figure 6 The figures are the chemical and wind erosion resistance test results of the specimens repaired with the repair material of the present invention. DETAILED DESCRIPTION

[0032] In order to better explain the present invention and facilitate understanding, the present invention is described in detail below through specific implementation methods in conjunction with the accompanying drawings.

[0033] Example 1

[0034] like Figure 1 The figure shows a flow chart for preparing the repair material for wind erosion damage in rammed earth ruins according to the present invention. The process includes:

[0035] S1. Prepare mineralized bacterial solution first

[0036] The mineralized bacterial solution comprises a live Bacillus pasteurianus strain and a liquid culture medium, wherein the liquid culture medium comprises sucrose as a carbon source and yeast powder as a nitrogen source. The sucrose concentration in the mineralized bacterial solution is 10-15 g / L, and the yeast powder concentration is 15-20 g / L. The Bacillus pasteurianus strain is in a logarithmic growth phase, and preferably has an optical density OD600 of 1-2, preferably 1.2. 0.01-0.1 mM urease inducer may be added to the mineralized bacterial solution. The urease inducer contains a nickel metalloenzyme that catalyzes the hydrolysis of urea into ammonia and carbon dioxide.

[0037] When preparing the bacterial solution, take the Bacillus pasteurianus strain and inoculate it into the liquid culture medium. Cultivate it at a temperature of 30℃ and shake it for 24-48 hours until the OD600 value of the bacterial solution reaches 1-2, thus obtaining a bacterial solution with high activity. Bacillus pasteurii ) strains that can be used include ATCC 11859, DSM 33, or KCTC 3558. The pH of the mineralized bacterial solution is 6-8.

[0038] S2. Preparation of cementing nutrient solution

[0039] Water-soluble calcium, wood calcium, corn cob powder, and urea are dissolved in water to obtain a cementitious nutrient solution. The water required for the cementitious nutrient solution can be natural rainfall, river water, well water, tap water, deionized water, etc. The corn cob powder in the cementitious nutrient solution is corn cob powder activated with potassium carbonate, added in an amount of 1-4wt% and a particle size of 0.05-0.25mm, preferably 0.1mm. Potassium carbonate activation of the corn cob powder increases the porosity of the corn cob powder, thereby improving its loading rate and loading capacity for CaCO3.

[0040] The water-soluble calcium is at least one of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate, and is preferably calcium chloride. Water-soluble calcium can quickly provide the calcium ions required for mineralization. The total molar concentration of water-soluble calcium is 0.1-2.0 mol / L. In some cases, the aqueous solution calcium is a complex calcium. If the complex calcium is a combination of calcium chloride and calcium lactate, calcium chloride can quickly release calcium ions to accelerate the initial mineralization rate, and calcium lactate slowly releases calcium ions, which can extend the mineralization cycle. Calcium lactate can also provide the carbon source required by microorganisms; the molar ratio of calcium chloride to calcium lactate in the complex calcium is 2-3:2. The molar concentration of urea is 0.5-1 times the calcium ion concentration in the water-soluble calcium, preferably 0.6-0.7 times; the urea concentration is preferably 0.05-1.0 mol / L.

[0041] Wood calcium is used to adjust the color of the repaired area, bringing it closer to the original color of the rammed earth site, achieving a restoration effect that reflects the original. The addition of wood calcium is 0.5-3wt%. The addition of wood calcium can meet the color difference requirements of rammed earth sites, ensuring that the color difference between the repaired area and the original soil is less than 5.

[0042] S3. After preparing the above-mentioned mineralizing bacterial solution and cementing nutrient solution, they must be stored separately. Before use, the mineralizing bacterial solution and the cementing nutrient solution must be mixed in a volume ratio of 1:1 to 1:2 to obtain a biomineralization precursor solution with flocculent matter. Ensure that it is ready for construction within 5-40 minutes. Apply the biomineralization precursor solution to the diseased areas of the rammed earth ruins three times a day, with an interval of at least 3 hours between two applications. Each application day constitutes one cycle. After 3-6 days of continuous treatment in the above manner, carry out natural curing. Preferably, the diseased areas of the rammed earth ruins include holes and cracks.

[0043] Example 2

[0044] In this embodiment, a repair material for wind erosion damage in rammed earth ruins was prepared according to the method of Example 1, and its composition is as follows:

[0045] The mineralized bacterial solution consists of: Bacillus pasteurianus (OD600 = 1.5), 12 g / L sucrose, and 18 g / L yeast extract. The Bacillus pasteurianus strain is ATCC 11859. The pH of the mineralized bacterial solution is 6-7.

[0046] The composition of the cementing nutrient solution is: 0.5M urea, 1.2 wt% wood calcium, 0.72M CaCl2, 2wt% potassium carbonate activated corn cob powder (particle size 0.1-0.2mm), deionized water. The amount of wood calcium added is based on Figure 2 Determined by the color difference test results of the test piece.

[0047] The mineralizing bacterial solution and the cementing nutrient solution are mixed in a volume ratio of 1:1, and floccules are gradually generated in the mineralizing solution to obtain a biomineralization precursor solution.

[0048] Select Figure 2 The picture of the indoor specimen of the rammed earth site shown is Figure 2 Figure a is a color difference test piece for rammed earth ruins, used to determine the most appropriate amount of wood calcium addition. Figure b is a simulated specimen for hole damage, and figure c is a simulated specimen for crack damage.

[0049] Here’s how to fix it:

[0050] Use within 25 minutes after mixing the mineralizing bacteria solution and the cementing nutrient solution. First, use a brush to apply the biomineralization precursor solution to the surface of the earthen ruins specimen. After each application, maintain it under natural conditions for 3 hours to ensure that the flocs are fully adsorbed on the soil surface and reduce water erosion and solution loss. Apply three times a day, each time under the same conditions. Before each application, prepare the repair material. Follow this operation for 6 days. After completion, place it under natural conditions and maintain it for one week to form a mineralized crust structure with wind erosion resistance. The repair process of the present invention adopts a local treatment method, and only applies to diseased areas such as cracks and holes, without filling the diseases to preserve their historical traces and beauty. The use of the smearing method can reduce the amount used and ensure that the material is firmly adsorbed on the diseased surface to form a uniform and strong mineralized crust, avoiding water erosion or damage to non-disease areas caused by spraying.

[0051] Examples 3-4

[0052] Example 3: Repair materials were prepared according to the method of Example 2, except that the 2 wt% corncob powder in the cementitious nutrient solution was adjusted to 4 wt% and 6 wt% respectively. Other preparation conditions and use methods of the repair materials are shown in Example 2.

[0053] Comparative Example 1

[0054] Comparative Example 1: A repair material was prepared according to the method of Example 2, except that 2 wt% of the corncob powder in the cementitious nutrient solution was removed, i.e., the corncob powder dosage was adjusted to zero. For other preparation conditions and use of the repair material, see Example 2.

[0055] The curves of the calcium ion conversion rate of the three repair materials of Example 2-4 and Comparative Example 1 over time are shown in the following table. Figure 3 wherein "2%" represents Example 2, "4%" represents Example 3, "6%" represents Example 4, and "0%" represents Comparative Example 1.

[0056] like Figure 3As shown, within 0-2h, compared with the repair material prepared by Comparative Example 1 without corn cob powder, the repair material of Example 2-4 has a significantly faster calcium ion conversion rate, and the calcium ion conversion rate of the three repair materials when the corn cob powder dosage is 2wt%, 4wt%, and 6wt% in the cementing nutrient solution has a certain difference before 2h, but almost overlaps at 2h. Therefore, in order to take into account cost, it is advisable to determine the addition amount of corn cob powder to be 1-4wt%, preferably 2-4wt%. Corn cob powder is a natural polysaccharide substance that not only provides a slow-release carbon source and nitrogen source for bacteria, but also because it has a porous structure and adsorption capacity, it can promote the attachment of microorganisms and the formation of biofilm, and accelerate the reaction rate of microbial mineralization. Potassium carbonate activation treatment further increases the porosity and hydrophilic groups of corn cob powder, further promotes the attachment of microorganisms, which is all conducive to improving the mineralization rate.

[0057] Comparative Example 2

[0058] Comparative Example 1: A repair material was prepared according to the method of Example 2, except that 1.2 wt% of the wood calcium in the cementing nutrient solution was removed, i.e., the wood calcium content was adjusted to zero. For other preparation conditions and usage of the repair material, see Example 2.

[0059] like Figure 4 As shown in the figure, the color difference of the rammed earth ruins specimens repaired with the repair material of Example 2 and the repair material of Comparative Example 2 is further compared. As shown in the figure, after the specimens were repaired and cured, the surface of the specimens repaired with the repair material of Comparative Example 2 showed a whitening phenomenon, with several white spots appearing, which detracted from the overall aesthetics. In contrast, the specimens repaired with the repair material of Example 2 of the present invention had a very uniform color distribution, with the repaired area showing the normal color of the soil. No color difference was observed with the naked eye, and the repaired area almost blended in with its surroundings.

[0060] This is because the active bacteria provided by the mineralized bacterial solution produce urease during their metabolism. When the solution contains a certain concentration of calcium ions, the calcium ions are adsorbed by the bacterial strain, forming CaCO3 crystals with a gelling effect around the bacteria. This forms a protective layer of calcium carbonate on the surface of the soil layer, which has the effect of repairing holes and small cracks. However, the CaCO3 crystals appear white, while the wood calcium appears brown. The introduction of wood calcium neutralizes the white color of the calcium carbonate precipitate, which has the effect of reducing color difference. Wood calcium (Calcium Lignosulfonate) is a type of lignin sulfonate, a by-product of the papermaking industry. Its chemical structure contains sulfonic acid groups and calcium ions. It appears as a yellow-brown powder or liquid and is easily soluble in water. The colorant used as a repair agent in the present invention not only achieves resource utilization, but also enables the repaired area to maintain the original soil color for a long time, presenting an effect of repairing the old as it was, and preventing whitening.

[0061] Furthermore, the rammed earth specimens repaired with the repair material of Example 2 and the rammed earth specimens without any repair treatment were placed in a wind erosion test with a wind speed of 20 m / s (equivalent to a force 8 gale) (sand carrying capacity of 200 g / m³, sand particles of 0.1-0.5 mm) for 20 minutes. 20 minutes after the end of the test, the erosion rate of each specimen was measured as follows: Figure 5 shown.

[0062] Depend on Figure 5 As can be seen, the erosion rates of the unrepaired hole and crack specimens were 2.33 times and 2.25 times higher, respectively, than those treated with the repair material of the present invention. This demonstrates that the repair material provided by the present invention can significantly inhibit the erosion process of rammed earth ruins, effectively improving their wind erosion resistance and achieving both repair and protection.

[0063] Example 5

[0064] This embodiment is based on Example 2, and 1.6wt% of rice husk ash mesoporous silica (pore size of 10-30nm) is further added to the cementitious nutrient solution. The specific surface area is 500-1000m² / g, and the particle size is 0.1-1μm. The rice husk ash mesoporous silica is obtained by directly calcining rice husk ash at a high temperature of >600°C, and its color is light gray. The rice husk ash mesoporous silica is sprayed with a 1.5wt% silane coupling agent ethanol solution and dried. For other preparation conditions and use methods of the repair material, please refer to Example 2. The pore size and dosage of the rice husk ash mesopores take into account the air permeability of the repaired area and the strength and weather resistance after repair, while the particle size mainly considers the repair and reinforcement effect of microcracks.

[0065] The rammed earth specimens repaired with the repair materials of Examples 2 and 5 were placed in a sealed test chamber. SO2 and NOx acid gases were introduced into the chamber to a concentration of 50 ppm for SO2 and 50 ppm for NOx. The test temperature was set at 25 ± 2°C and the humidity was 75 ± 5%. After 48 hours of sealed treatment, the specimens were removed and placed in a wind speed of 20 m / s (see Figure 5 The wind erosion test was carried out for 20 minutes under the sand-carrying wind condition (test conditions). 20 minutes after the test, the erosion rate of each specimen was measured as follows: Figure 6 As shown. Figure 6 As shown, the mass loss of the rammed earth specimens repaired with the repair material of Example 5 was less than that of the rammed earth specimens repaired with the repair material of Example 2, with the former losing only about 50% of the mass loss of the latter. This shows that adding a small amount of rice husk ash mesoporous silica to the cementitious nutrient solution significantly reduces the overall erosion rate of the specimens, resulting in improved weather resistance of the repaired specimens.

[0066] The above examples demonstrate that the microbial mineralization-based repair material for rammed earth ruins wind erosion damage of the present invention is a highly efficient repair agent that combines rapid mineralization with satisfactory color variability. During the repair process, Bacillus pasteurianus produces urease through metabolism, which decomposes urea into ammonium and carbonate ions, forming calcium carbonate crystals between particles that act as a binder. Corncob powder, a natural polysaccharide, not only provides a nitrogen source and energy for the bacterial solution but also, due to its porous structure, increases the reactive surface area, promoting microbial attachment and accelerating the mineralization reaction (increasing the conversion rate of calcium ions). The addition of wood calcium effectively neutralizes the white color of the calcium carbonate precipitate by utilizing its brown color, significantly reducing color variability. After application, the repair material rapidly forms a durable crust on the surface of the rammed earth ruin damage, effectively inhibiting further deterioration. The present method offers advantages such as environmental friendliness, ease of operation, and long-lasting repair effects. It is suitable for the repair of wind erosion damage in rammed earth ruins and presents significant research and application prospects.

[0067] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the above embodiments, or make equivalent replacements for some or all of the technical features therein. These modifications or replacements, or when the technical features in the above embodiments do not conflict with each other, can be combined in the manner described in the embodiments, and these modifications, replacements or combinations do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A repair material for wind erosion damage in rammed earth ruins, characterized in that: Including mineralizing bacterial solution and cementing nutrient solution; The mineralized bacterial liquid contains a living Bacillus pasteurianus strain and a liquid culture medium, wherein the liquid culture medium contains sucrose as a carbon source and yeast powder as a nitrogen source; the cementing nutrient solution is an aqueous solution containing water-soluble calcium, wood calcium, corn cob powder and urea; and the corn cob powder is corn cob powder activated with potassium carbonate; The mineralizing bacterial solution and the cementing nutrient solution are stored separately, and are mixed and formulated before use to obtain a repair material for wind erosion damage at rammed earth ruins.

2. The repair material according to claim 1, characterized in that The Bacillus pasteurianus strain in the mineralized bacterial solution is in a logarithmic growth phase, and its optical density OD600 is 1-2.

3. The repair material according to claim 1, characterized in that The sucrose concentration in the mineralized bacterial solution is 10-15 g / L, and the yeast powder concentration is 15-20 g / L.

4. The repair material according to claim 1, characterized in that The molar concentration of urea in the cementing nutrient solution is 0.5-1 times the concentration of calcium ions in water-soluble calcium; the molar concentration of urea is 0.05-1.0 mol / L; and the amount of wood calcium added to the cementing nutrient solution is 0.5-3 wt%.

5. The repair material according to claim 1, characterized in that The water-soluble calcium in the cementing nutrient solution is at least one of calcium chloride, calcium nitrate, calcium acetate and calcium lactate.

6. The repair material according to claim 5, characterized in that The calcium in the aqueous solution is compound calcium, which is a combination of calcium chloride and calcium lactate; in the compound calcium, the molar ratio of calcium chloride to calcium lactate is 2-3:

2.

7. The repair material according to claim 1, characterized in that The concentration of corn cob powder in the cementing nutrient solution is 1-4wt%, and the particle size of the corn cob powder is 0.05-0.25mm.

8. The repair material according to claim 1, characterized in that The cementing nutrient solution is further added with 1-3 wt% of rice husk ash mesoporous silica with a pore size of 10-30 nm and a particle size of 0.1-1 μm.

9. The repair material according to claim 1, characterized in that Silane coupling agent grafted onto the surface of mesoporous silica from rice husk ash.

10. A method for repairing wind erosion damage in rammed earth ruins, characterized in that: The steps include: The repair material according to any one of claims 1 to 9 is used for repair construction, wherein the mineralizing bacterial solution and the cementing nutrient solution are mixed in a volume ratio of 1:1 to 1:2 to form a biomineralization precursor solution; and the repair construction is carried out within 5 to 40 minutes after the biomineralization precursor solution is obtained by mixing; The biomineralization precursor solution is applied to the diseased parts of the rammed earth ruins, 3 times a day, with an interval of at least 3 hours between two adjacent applications, and each day of application is considered a round. After 3-6 consecutive days of treatment, natural curing is carried out; the diseased parts of the rammed earth ruins include hole diseases and crack diseases.

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