A bio-based repair material for stone cultural relics restoration and its preparation method

Abstract

The present invention discloses a bio-based repair material for stone cultural relics and its preparation method, which is composed of modified stone powder, modified fine stone materials, bacterial sludge, biopolymer, cementing solution and modified basalt fiber. By adopting the technical solution of the present invention, the problems of poor compatibility, low repair efficiency and insufficient mechanical properties of traditional repair materials are solved. At the same time, the green sustainability of the repair process is realized, and it is widely applicable to the crack filling, surface damage reinforcement and structural repair of stone cultural relics.

Description

Technical Field

[0001] The present invention belongs to the technical field of ecological restoration materials, and particularly relates to a bio-based restoration material for the restoration of stone cultural relics and a preparation method thereof. Background Art

[0002] Due to long-term exposure to the natural environment, stone cultural relics are vulnerable to multiple factors such as physical (temperature changes, freeze-thaw cycles), chemical (acid rain erosion, salt crystallization), and biological (microorganisms, plant roots), resulting in surface deterioration, crack expansion, and even structural instability. Traditional restoration techniques mainly rely on the following materials: (1) inorganic materials (such as lime-based and cement-based materials), although they have low costs, their compatibility is poor, and they are prone to salt crystallization, which damages the stone cultural relics themselves; (2) organic synthetic materials (such as epoxy resins and acrylic resins): they have high initial bonding strength, but are prone to aging and yellowing, release harmful substances, and are irreversible restorations, hindering subsequent protection; (3) pure biomineralization materials (such as MICP technology): they are environmentally friendly but have low mineralization efficiency and insufficient mechanical strength, making it difficult to repair large damaged areas and deep cracks.

[0003] In recent years, bio-based restoration materials have become a research hotspot, but the existing technologies still have the following problems: (1) low utilization rate of waste stones: the waste materials of the stone cultural relics themselves are not fully utilized, resulting in a mismatch between the mineral composition of the restoration layer and the original stone; (2) insufficient microbial activity: the permeability of the bacterial community in complex pores is poor, the mineralization efficiency is low, and the distribution of mineralization products is uneven; (3) mechanical property bottleneck: it is difficult for the restoration material to balance its compressive, flexural, and crack resistance properties by using a single mineralization enhancement method. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide a bio-based restoration material for the restoration of stone cultural relics and a preparation method thereof.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A bio-based restoration material for the restoration of stone cultural relics is composed of modified stone powder, modified fine stone materials, bacterial sludge, biopolymer, cementing solution, and modified basalt fibers; wherein,

[0007] The mass ratio of the modified stone powder to the modified fine stone materials is 1:(0 - 1);

[0008] The incorporation amount of the bacterial sludge is 5% - 10% of the total mass of the modified stone powder and the modified fine stone materials;

[0009] The incorporation amount of the biopolymer is 1.0% - 1.5% of the total mass of the modified stone powder and the modified fine stone materials;

[0010] The dosage of the modified basalt fiber is 0.5%-1.0% of the total volume of the modified stone powder, modified fine aggregate, bacterial sludge and biopolymer;

[0011] The dosage of the cementing solution is 10%-25% of the total mass of the modified stone powder, modified fine aggregate, bacterial sludge and biopolymer.

[0012] Preferably, the biopolymer is composed of xanthan gum, chitosan and calcium lignosulfonate, and their mass ratio is 1:1:1.

[0013] Preferably, the cementing solution is composed of 2% urea, 1% CaCl2 and 0.5% yeast extract.

[0014] Preferably, the modified basalt fiber is basalt fiber modified by acidification, and its length is cut to 1-5 mm.

[0015] The present invention also provides a preparation method of a bio-based repair material for stone cultural relics restoration, including:

[0016] Step 1: Add the modified stone powder, modified fine aggregate, biopolymer, bacterial sludge and modified basalt fiber into a mixer according to the designed proportion, and stir and mix at a low speed for 5-10 min until the mixture is uniform; then slowly add the cementing solution, adjust the stirring speed to 100-150 r / min, and continue for 15 min to form a homogeneous composite slurry; among them, the low-speed stirring speed is 50-70 r / min;

[0017] Step 2: Let the composite slurry stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the bubbles, coat it on the damaged part of the stone cultural relic or inject it into the crack;

[0018] Step 3: Sprinkle the cementing solution on the surface of the repair material for curing for 7-14 days.

[0019] Preferably, the preparation steps of the modified stone powder, modified fine aggregate and bacterial sludge are as follows:

[0020] S1: Crush the waste stone produced by the stone cultural relics to be restored, screen to obtain stone powder with a particle size less than 0.1 mm and fine aggregate with a particle size of 0.1-2 mm, clean them in deionized water with an ultrasonic cleaner for 30 min to remove surface impurities; then dry them in an oven at 50-60 °C for 12 h, and control the moisture content below 1%;

[0021] S2: Prepare a citric acid solution with a concentration of 1 - 3 mol / L. Immerse the stone powder and fine stone materials in the citric acid solution according to a solid-liquid ratio of 1:5, and let them stand at room temperature for 24 - 48 h, stirring every 8 h for 5 min each time. Rinse the treated stone powder and fine stone materials with deionized water until the pH reaches 6.8 - 7.2, and then dry them in an oven at 50 - 60 °C for later use.

[0022] S3: Extract the indigenous flora from the surface of the stone cultural relics, inoculate it into the liquid medium of Bacillus pasteurii, add 5% - 10% of the stone powder to the medium, and shake and culture it at 25 - 40 °C and 80 - 150 r / min for 3 - 5 days to screen out the Bacillus pasteurii strains with high affinity for the stone materials. Inoculate the domesticated strains into the liquid medium of Bacillus pasteurii to obtain the Bacillus pasteurii bacterial liquid. Then culture it at 25 - 40 °C until the OD600 of the bacterial liquid is 1.0 ± 0.2, and then centrifuge to obtain the bacterial sludge.

[0023] S4: Immerse the acidified stone powder and fine stone materials in the Bacillus pasteurii bacterial liquid, and let them stand at room temperature for 48 - 72 h. During this period, supplement 0.5 mol / L urea and CaCl2 solution every 12 h. Then take out the stone powder and fine stone materials and drain them at room temperature to obtain the modified stone powder and activated fine stone materials.

[0024] S5: Mix the activated fine stone materials and the bacterial sludge according to a mass ratio of 7:3, place them in a vacuum reactor, evacuate to -0.08 - -0.05 MPa, and maintain for 12 - 24 h to allow the bacterial sludge to penetrate into the pores of the fine stone materials. After releasing the vacuum, cure at 25 - 40 °C for 24 h to obtain the modified fine stone materials.

[0025] The present invention uses the waste stone materials of the stone cultural relics as the matrix, and through the technologies of waste stone material gradient modification, flora directional domestication, and bio-polymer - modified basalt fiber synergistic enhancement, prepares a bio-based composite material with high compatibility, high strength, and ecological environmental protection. It solves the problems of poor compatibility, low repair efficiency, and insufficient mechanical properties of traditional repair materials, and at the same time realizes the green sustainability of the repair process. It is widely applicable to the crack filling, surface damage reinforcement, and structural repair of stone cultural relics, and has the following technical effects:

[0026] 1. Make full use of the waste materials of the stone cultural relics to achieve a high degree of matching of the mineral, structure, and mechanical properties between the repair material and the stone cultural relics.

[0027] 2. After acidification and microbial activation modification, the stone powder forms a porous structure, providing mineral compatibility and flora attachment sites. Loading the bacterial sludge into the internal pores of the fine stone materials can significantly increase the number of microbial cells in the repair material. After the modification of the stone powder and fine stone materials, the problems of poor permeability of the flora in the repair material, low mineralization efficiency, and uneven distribution of mineralization products are solved.

[0028] 3. The repair material is incorporated with bacterial sludge, biopolymer and modified basalt fibers. The latter two are intertwined to form a three-dimensional toughness-enhancing network, which synergistically acts with the calcium carbonate crystals of the microbial mineralization product of the former to wrap, cement and interweave the modified stone powder and modified fine stone materials to form an integral structure, greatly improving the compressive, flexural and crack resistance of the bio-based repair material.

[0029] 4. The product components of the repair material are all natural minerals and organic substances, which have strong compatibility with the main body material of stone cultural relics, no secondary pollution, are ecological and environmentally friendly, and the material is produced at low temperature during the production process, and its energy consumption is significantly reduced compared with traditional materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only the embodiments of the present invention. For those of ordinary skill in the art, other drawings can be obtained according to the provided drawings without creative efforts.

[0031] Figure 1 It is a flowchart of the preparation method of the bio-based repair material for stone cultural relics restoration in the embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0033] In order to make the above objects, features and advantages of the present invention more obvious and understandable, the present invention will be further described in detail below with reference to the drawings and specific embodiments.

[0034] Example 1:

[0035] As Figure 1 shown, the embodiment of the present invention provides a bio-based repair material for stone cultural relics restoration, which is composed of modified stone powder, modified fine stone materials, bacterial sludge, biopolymer, cementing solution and modified basalt fibers; among them,

[0036] The mass ratio of the modified stone powder to the modified fine stone materials is 1:(0 - 1);

[0037] The incorporation amount of the bacterial sludge is 5% - 10% of the total mass of the modified stone powder and the modified fine stone materials;

[0038] The incorporation amount of the biopolymer is 1.0% - 1.5% of the total mass of the modified stone powder and the modified fine aggregate;

[0039] The incorporation amount of the modified basalt fiber is 0.5% - 1.0% of the total volume of the modified stone powder, the modified fine aggregate, the bacterial sludge and the biopolymer;

[0040] The incorporation amount of the cementing solution is 10% - 25% of the total mass of the modified stone powder, the modified fine aggregate, the bacterial sludge and the biopolymer.

[0041] As an implementation mode of the embodiment of the present invention, the modified stone powder: the particle size is <0.1 mm, and after acidification and microbial activation, a porous structure is formed to provide mineral compatibility and bacterial attachment sites.

[0042] As an implementation mode of the embodiment of the present invention, the modified fine aggregate: the particle size is 0.1 - 2 mm, which constructs the skeleton structure of the repair material and controls and adjusts the density of the repair material; a large amount of bacterial sludge is adsorbed in the internal pores of the modified fine aggregate, significantly increasing the number of microbial cells in the repair material.

[0043] As an implementation mode of the embodiment of the present invention, the bacterial sludge: domesticated Bacillus pasteurii cells, secrete urease to decompose urea to generate , and combine to form calcium carbonate crystals for filling and cementing the modified stone powder and the modified fine aggregate.

[0044] As an implementation mode of the embodiment of the present invention, the biopolymer is composed of xanthan gum, chitosan and calcium lignosulfonate, and their mass ratio is 1:1:1; the biopolymer is used to wrap and cement the modified stone powder and the modified fine aggregate to form a three-dimensional tough network structure, which synergistically acts with the microbial mineralization product calcium carbonate crystals to improve the mechanical and durability properties of the repair material.

[0045] As an implementation mode of the embodiment of the present invention, the cementing solution is composed of 2% urea, 1% CaCl2 and 0.5% yeast extract; it has the function of activating the bacterial community and improving the metabolism and mineralization ability of the bacterial community.

[0046] As an implementation mode of the embodiment of the present invention, the modified basalt fiber is basalt fiber modified by acidification, and its length is cut to 1 - 5 mm; after acidification modification, the surface roughness increases, and it interweaves with the biopolymer to form a three-dimensional reinforcement network, inhibiting the crack propagation of the repair material.

[0047] Example 2:

[0048] The embodiment of the present invention also provides a preparation method of a bio-based repair material for stone cultural relics repair, including:

[0049] Step 1: Add modified stone powder, modified fine stone materials, biopolymer, bacterial sludge, and modified basalt fibers into a blender according to the designed proportion, and stir and mix them at a low speed for 5 - 10 min until the mixture is uniform; then slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue stirring for 15 min to form a homogeneous composite slurry; among them, the low-speed stirring speed is 50 - 70 r / min;

[0050] Step 2: Let the composite slurry stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the bubbles, coat it on the damaged part of the stone cultural relic or inject it into the crack;

[0051] Step 3: Sprinkle the cementing solution on the surface of the repair material for curing for 7 - 14 days.

[0052] As an implementation mode of the embodiment of the present invention, the preparation steps of the modified stone powder, modified fine stone materials, and bacterial sludge are as follows:

[0053] S1: Crush the waste stone materials generated from the stone cultural relics to be repaired, and screen to obtain stone powder with a particle size less than 0.1 mm and fine stone materials with a particle size of 0.1 - 2 mm. Wash them in deionized water with an ultrasonic cleaner for 30 min to remove surface impurities; then dry them in an oven at 50 - 60 °C for 12 h, and control the moisture content below 1%;

[0054] S2: Prepare a 1 - 3 mol / L citric acid solution, immerse the stone powder and fine stone materials in the citric acid solution according to a solid-liquid ratio of 1:5 respectively, let them stand at room temperature for 24 - 48 h, stir once every 8 h, and each stirring lasts for 5 min; rinse the treated stone powder and fine stone materials with deionized water until the pH = 6.8 - 7.2, and then dry them in an oven at 50 - 60 °C for standby;

[0055] S3: Extract indigenous bacteria from the surface of the stone cultural relics, inoculate them into the liquid medium of Bacillus pasteurii, add 5% - 10% of stone powder to the medium, and shake and culture them at 25 - 40 °C and 80 - 150 r / min for 3 - 5 days to screen out the Bacillus pasteurii strains with high affinity for stone materials; continue to inoculate the domesticated strains into the liquid medium of Bacillus pasteurii to obtain Bacillus pasteurii bacterial liquid; then culture it at 25 - 40 °C until the OD600 of the bacterial liquid = 1.0 ± 0.2, and then centrifuge to obtain bacterial sludge;

[0056] S4: Immerse the acidified stone powder and fine stone materials in the Bacillus pasteurii bacterial liquid, let them stand at room temperature for 48 - 72 h, supplement 0.5 mol / L urea and CaCl2 solution every 12 h during this period, and then take out the stone powder and fine stone materials and drain them at room temperature to obtain modified stone powder and activated fine stone materials;

[0057] S5: Mix the activated fine aggregate and the bacterial sludge in a mass ratio of 7:3, place them in a vacuum reactor, evacuate to -0.08 to -0.05 MPa, and maintain for 12 - 24 h to allow the bacterial sludge to penetrate into the pores of the fine aggregate. After releasing the vacuum, cure at 25 - 40 °C for 24 h to obtain the modified fine aggregate.

[0058] Example 1: Bio-based repair material (only containing modified stone powder)

[0059] 1. Raw material ratio

[0060] Modified stone powder: fine aggregate = 1:0;

[0061] Dosage of bacterial sludge 5% (by mass of stone powder);

[0062] Dosage of biopolymer (xanthan gum: chitosan: calcium lignosulfonate = 1:1:1) 1.0%;

[0063] Dosage of cementing solution 10%;

[0064] Volume dosage of modified basalt fiber 0.5%.

[0065] 2. Preparation process

[0066] Prepare the modified stone powder and the bacterial sludge according to steps S1 - S4.

[0067] First, add the modified stone powder, biopolymer, bacterial sludge, and modified basalt fiber into a mixer according to the designed ratio, and stir at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is uniform; secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite slurry; then let the composite slurry stand indoors for 30 min or be treated in a vacuum degassing machine for 5 min. After removing the bubbles, pour the slurry into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then place them in a room-temperature environment and continue to cure until 14 d. Sprinkle the cementing solution on the surface of the specimens once every 12 h during the curing period. Place the specimens cured for 14 d in an oven at 60 °C and dry for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14-d compressive strength of the specimens is 2.18 MPa, and the average 14-d splitting tensile strength is 0.27 MPa.

[0068] Example 2: Bio-based repair material (only containing modified stone powder)

[0069] 1. Raw material ratio

[0070] Modified stone powder: modified fine aggregate = 1:0;

[0071] The dosage of bacterial sludge is 8% (by mass of stone powder);

[0072] The dosage of biopolymer (xanthan gum: chitosan: calcium lignosulfonate = 1:1:1) is 1.2%;

[0073] The dosage of cementing solution is 15%;

[0074] The volume dosage of modified basalt fiber is 0.8%.

[0075] 2. Preparation process

[0076] Prepare the modified stone powder and bacterial sludge according to steps S1 - S4.

[0077] First, add the modified stone powder, biopolymer, bacterial sludge, and modified basalt fiber into a mixer according to the designed proportions, and stir at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is uniform; secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite slurry; then, let the composite slurry stand indoors for 30 min or be treated in a vacuum degassing machine for 5 min. After removing the air bubbles, pour the slurry into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then place them in a room-temperature environment and continue to cure until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry them for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14-d compressive strength of the specimens is 4.43 MPa, and the average 14-d splitting tensile strength is 0.66 MPa.

[0078] Example 3: Bio-based repair material (only containing modified stone powder)

[0079] 1. Raw material ratio

[0080] Modified stone powder: Modified fine aggregate = 1:0;

[0081] The dosage of bacterial sludge is 10% (by mass of stone powder);

[0082] The dosage of biopolymer (xanthan gum: chitosan: calcium lignosulfonate = 1:1:1) is 1.5%;

[0083] The dosage of cementing solution is 25%;

[0084] The volume dosage of modified basalt fiber is 1.0%.

[0085] 2. Preparation process

[0086] Prepare the modified stone powder and bacterial sludge according to steps S1 - S4.

[0087] First, add the modified stone powder, biopolymer, bacterial sludge, and modified basalt fibers into a blender according to the designed proportions, and mix them at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is uniform. Secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite slurry. Then, let the composite slurry stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the air bubbles, pour the slurry into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then continue to cure them in a room temperature environment until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry them for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14 - d compressive strength of the specimens is 4.97 MPa, and the average 14 - d splitting tensile strength is 0.83 MPa.

[0088] Control Example 1: Traditional bio - based repair material (only contains stone powder)

[0089] 1. Raw material ratio

[0090] Stone powder: fine aggregate = 1:0;

[0091] Dosage of bacterial liquid is 10%;

[0092] Dosage of cementing solution is 10%.

[0093] 2. Preparation process

[0094] First, add the stone powder and bacterial liquid into a blender according to the designed proportions, and mix them at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is uniform. Secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous slurry. Then, let the slurry stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the air bubbles, pour the slurry into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then continue to cure them in a room temperature environment until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry them for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14 - d compressive strength of the specimens is 1.28 MPa, and the average 14 - d splitting tensile strength is 0.10 MPa.

[0095] Example 4: Bio - based repair material (contains modified stone powder and modified fine aggregate)

[0096] 1. Raw material ratio

[0097] Modified stone powder: modified fine aggregate = 1:0.5;

[0098] Dosage of bacterial sludge is 5%;

[0099] Dosage of biopolymer (xanthan gum: chitosan: calcium lignosulfonate = 1:1:1) is 1.0%;

[0100] Dosage of cementing solution is 10%;

[0101] Volume dosage of modified basalt fiber is 0.5%.

[0102] 2. Preparation process

[0103] Prepare modified stone powder, modified fine aggregate and bacterial sludge according to steps S1 - S5;

[0104] First, add modified stone powder, modified fine aggregate, biopolymer, bacterial sludge and modified basalt fiber into a mixer according to the designed ratio, and stir at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is uniform; secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite slurry; then let the composite slurry stand indoors for 30 min or be treated in a vacuum degassing machine for 5 min. After removing the bubbles, pour the slurry into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then place them in a room temperature environment to continue curing until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14 - d compressive strength of the specimens is 3.99 MPa, and the average 14 - d splitting tensile strength is 0.48 MPa.

[0105] Example 5: Bio - based repair material (containing modified stone powder and modified fine aggregate)

[0106] 1. Raw material ratio

[0107] Modified stone powder: modified fine aggregate = 1:1;

[0108] Dosage of bacterial sludge is 8%;

[0109] Dosage of biopolymer (xanthan gum: chitosan: calcium lignosulfonate = 1:1:1) is 1.2%;

[0110] Dosage of cementing solution is 15%;

[0111] The volume fraction of modified basalt fiber is 0.8%.

[0112] 2. Preparation process

[0113] Prepare modified stone powder, modified fine aggregate and bacterial sludge according to steps S1 - S5;

[0114] First, add modified stone powder, modified fine aggregate, biopolymer, bacterial sludge and modified basalt fiber into a mixer according to the designed proportion, and mix at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is uniform; Second, slowly add the cementing solution, adjust the mixing speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite slurry; Then, let the composite slurry stand indoors for 30 min or be treated in a vacuum degassing machine for 5 min. After removing the air bubbles, pour the slurry into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then place them in a room temperature environment for continued curing until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry them for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14 - d compressive strength of the specimens is 8.84 MPa, and the average 14 - d splitting tensile strength is 1.49 MPa.

[0115] Example 6: Bio - based repair material (containing modified stone powder and modified fine aggregate)

[0116] 1. Raw material ratio

[0117] Modified stone powder: Modified fine aggregate = 1:1;

[0118] The content of bacterial sludge is 10%;

[0119] The content of biopolymer (xanthan gum: chitosan: calcium lignosulfonate = 1:1:1) is 1.5%;

[0120] The content of cementing solution is 25%;

[0121] The volume fraction of modified basalt fiber is 1.0%.

[0122] 2. Preparation process

[0123] Prepare modified stone powder, modified fine aggregate and bacterial sludge according to steps S1 - S5;

[0124] First, add the modified stone powder, modified fine aggregate, biopolymer, bacterial sludge, and modified basalt fiber into a blender according to the designed proportions, and mix them at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is homogeneous. Secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite paste. Then, let the composite paste stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the air bubbles, pour the paste into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then continue to cure them in a room-temperature environment until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry them for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14-d compressive strength of the specimens is 9.66 MPa, and the average 14-d splitting tensile strength is 1.84 MPa.

[0125] Comparative Example 2: Traditional bio-based repair material (containing stone powder and fine aggregate)

[0126] 1. Raw material ratio

[0127] Stone powder: Fine aggregate = 1:1;

[0128] Dosage of bacterial liquid is 10%;

[0129] Dosage of cementing solution is 10%.

[0130] 2. Preparation process

[0131] First, add the stone powder, fine aggregate, and bacterial liquid into a blender according to the designed proportions, and mix them at a low speed (50 - 70 r / min) for 5 - 10 min until the mixture is homogeneous. Secondly, slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous paste. Then, let the paste stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the air bubbles, pour the paste into a cylindrical mold with a diameter of 5 cm and a height of 10 cm and compact it. A total of 6 specimens are prepared. Demold the specimens after curing at room temperature for 3 d, and then continue to cure them in a room-temperature environment until 14 d. During the curing period, spray the cementing solution on the surface of the specimens once every 12 h. Place the specimens cured for 14 d in an oven at 60 °C and dry them for 2 h. After taking out the specimens, conduct unconfined compressive strength tests and splitting tensile strength tests respectively. Each group of tests has 3 specimens. The average 14-d compressive strength of the specimens is 1.89 MPa, and the average 14-d splitting tensile strength is 0.15 MPa.

[0132] The embodiments described above are only descriptions of the preferred embodiments of the present invention and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various deformations and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the claims of the present invention.

Claims

1. A bio-based repair material for the restoration of stone cultural relics, characterized in that, It is composed of modified stone powder, modified fine stone materials, bacterial sludge, biopolymer, cementing solution, and modified basalt fiber; among them, The mass ratio of the modified stone powder to the modified fine stone materials is 1:(0 - 1); The incorporation amount of the bacterial sludge is 5% - 10% of the total mass of the modified stone powder and the modified fine stone materials; The incorporation amount of the biopolymer is 1.0% - 1.5% of the total mass of the modified stone powder and the modified fine stone materials; The incorporation amount of the modified basalt fiber is 0.5% - 1.0% of the total volume of the modified stone powder, modified fine stone materials, bacterial sludge, and biopolymer; The incorporation amount of the cementing solution is 10% - 25% of the total mass of the modified stone powder, modified fine stone materials, bacterial sludge, and biopolymer; The biopolymer is composed of xanthan gum, chitosan, and calcium lignosulfonate, and their mass ratio is 1:1:1; The cementing solution is composed of 2% urea, 1% CaCl2, and 0.5% yeast extract; The modified basalt fiber is basalt fiber modified by acidification, and its length is cut to 1 - 5 mm; The modified stone powder is obtained by immersing acidified stone powder in the liquid of Bacillus pasteurii for modification; the modified fine stone materials are obtained by first immersing acidified fine stone materials in the liquid of Bacillus pasteurii for activation, and then mixing the activated fine stone materials with bacterial sludge for modification; The preparation steps of the modified stone powder, modified fine stone materials, and bacterial sludge are as follows: S1: Crush the waste stone materials generated from the stone cultural relics to be repaired, and screen to obtain stone powder with a particle size less than 0.1 mm and fine stone materials with a particle size of 0.1 - 2 mm. Wash them in deionized water with an ultrasonic cleaner for 30 min to remove surface impurities; then dry them in an oven at 50 - 60 °C for 12 h, and control the moisture content to be below 1%; S2: Prepare a citric acid solution with a concentration of 1 - 3 mol / L. Immerse the stone powder and fine stone materials in the citric acid solution according to a solid-liquid ratio of 1:5 respectively, and let them stand at room temperature for 24 - 48 h, stirring once every 8 h, with each stirring lasting for 5 min; rinse the treated stone powder and fine stone materials with deionized water until the pH = 6.8 - 7.2, and then dry them in an oven at 50 - 60 °C for standby; S3: Extract the indigenous flora from the surface of the stone cultural relics, inoculate it into the liquid medium of Bacillus pasteurii, add 5% - 10% of the stone powder to the medium, and shake and culture it at 25 - 40 °C and 80 - 150 r / min for 3 - 5 days to screen out the Bacillus pasteurii strains with high affinity for the stone materials; continue to inoculate the domesticated strains into the liquid medium of Bacillus pasteurii to obtain the liquid of Bacillus pasteurii; then culture it at a temperature of 25 - 40 °C until the OD600 of the liquid is 1.0 ± 0.2, and then centrifuge to obtain the bacterial sludge; S4: Immerse the acidified stone powder and fine stone materials in the liquid of Bacillus pasteurii, let them stand at room temperature for 48 - 72 h, and supplement 0.5 mol / L urea and CaCl2 solution every 12 h during this period. Then take out the stone powder and fine stone materials and drain them at room temperature to obtain the modified stone powder and activated fine stone materials; S5: Mix the activated fine aggregates and the bacterial sludge at a mass ratio of 7:3, place them in a vacuum reactor, evacuate to -0.08 to -0.05 MPa, and maintain for 12 - 24 h to allow the bacterial sludge to penetrate into the pores of the fine aggregates. After releasing the vacuum, cure at 25 - 40 °C for 24 h to obtain modified fine aggregates.

2. A preparation method of a bio-based repair material for stone cultural relics restoration as described in claim 1, characterized in that, Including: Step 1: Add the modified stone powder, modified fine aggregates, biopolymer, bacterial sludge, and modified basalt fibers into a mixer according to the designed proportions, and stir and mix at a low speed for 5 - 10 min until the mixture is uniform; then slowly add the cementing solution, adjust the stirring speed to 100 - 150 r / min, and continue for 15 min to form a homogeneous composite paste; among them, the low-speed stirring speed is 50 - 70 r / min. Step 2: Let the composite paste stand indoors for 30 min or place it in a vacuum degassing machine for 5 min. After removing the bubbles, coat it on the damaged parts of the stone cultural relics or inject it into the cracks. Step 3: Sprinkle the cementing solution on the surface of the repair material for curing for 7 - 14 days.

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