Microbial agent separation double-system self-repairing concrete and preparation method thereof

Abstract

The invention relates to the technical field of microbial concrete materials, in particular to microbial agent separation double-system self-repairing concrete and a preparation method. The self-repairing concrete is prepared from the following raw materials in parts by weight: 1100 to 1300 parts of coarse aggregate, 500 to 560 parts of river sand, 30 to 40 parts of silica fume, 300 to 425 parts of ordinary Portland cement (P.O 42.5), 5 to 6 parts of a water reducing agent, 90 to 120 parts of a carrier loaded with microorganisms and 240 to 260 parts of large-particle-size porous particles loaded with nutrient substances, wherein the microorganisms adopt bacillus coriolis and denitrifying bacteria; the preparation method is used for preparing the self-repairing concrete, the problem that reliable repairing cannot be achieved due to one-time consumption of the fungicide in the concrete self-repairing process is solved, the durability of the concrete structure under the freezing and thawing cycle effect is improved, and the service life of the concrete in the extreme environment is greatly prolonged.

Description

Technical Field

[0001] The present invention relates to the technical field of microbial concrete materials, and in particular to a bacterial agent separation dual-system self-repairing concrete and a preparation method thereof. Background Art

[0002] With the development of economy, building space has gradually extended to plateaus, underground, offshore and other dimensions. The application environment of concrete structures has become more diverse and complex. In the cold regions of northern my country, concrete structures such as reservoirs, dams, and ports built on water levels or in shallow groundwater areas are prone to periodic cracking and damage due to periodic freeze-thaw cycles. Most super-large projects are reinforced concrete structures. During the construction and use of concrete, it is affected by factors such as design, construction, service environment, and its own shrinkage and creep. When it is put into use, there are some visible original defects, such as microcracks and micropores. These original defects make the mechanical properties of concrete structures easily affected by external loads and the environment and change, reducing their durability. When The microcracks and micropores inside the concrete are in a saturated state. When the outside temperature changes positively or negatively, the pore water will freeze in the capillary pores, causing the cavity to expand, generating pore water pressure and migration pressure. The segregation of ice and pore water pressure will cause volume expansion, and the volume expansion and osmotic pressure of the concrete will induce the expansion of the cement paste, leading to the growth of porosity and microcracks, and advancing the initiation time of cracks. With the increase in the number of freeze-thaw cycles, the freezing and thawing of the internal pore water will cause obvious fatigue damage to the concrete structure, leading to an increase in internal microcracks, accelerated expansion of the main cracks, and interconnection of cracks and microcracks, which will eventually lead to the destruction of the internal void structure of the concrete, a decrease in the mechanical properties of the structure, and a loss of safety and durability.

[0003] Based on the freeze-thaw damage mechanism of concrete, research on concrete mechanical damage at home and abroad has been carried out from two aspects: on the one hand, delaying the expansion of freeze-thaw damage from a microscopic perspective, that is, adding air-entraining agent into concrete to increase the micro-closed pores in concrete and improve the pore structure of concrete. However, air-entrained concrete will reduce the strength of the structure and cannot guarantee the durability of the structure; on the other hand, avoiding the development of mesoscopic damage to the macroscopic from a microscopic perspective, that is, pre-loading repair materials in concrete. After the concrete suffers freeze-thaw damage, the existing cracks are repaired by repair materials to ensure the durability of the structure; and pre-loading repair materials in concrete can make concrete have the ability of self-sensing and self-repairing cracks, improve the self-healing ability of concrete cracks, and ensure the strength of concrete, which is extremely important for ensuring the safety and durability of buildings.

[0004] In the prior art, there are studies on self-repairing concrete, such as the Bacillus cereus strain isolated from the soil in Qatar, and the preparation of biological self-repairing concrete through MICP. The Bacillus cereus strain was encapsulated in sodium alginate beads and then mixed into cement mortar. After local strain strain, it can fill the microscopic pores on the concrete.

[0005] For example, the utility model patent with publication number CN208717174U discloses a self-repairing concrete structure containing hollow fibers, which solves the problem of reduced alkalinity of concrete during the self-repair process and reduces the possibility of corrosion of steel bars.

[0006] However, the above structure can only repair concrete a limited number of times and is not suitable for concrete structures subject to freeze-thaw cycles. When concrete is subjected to freeze-thaw cycles, the self-repair rate of concrete is often lower than the cycle rate of thawing during the day and freezing at night. Cracks will appear and develop repeatedly, and one-time repair cannot meet the needs of actual engineering structures.

[0007] Therefore, there is an urgent need to provide a bacterial agent separation dual system self-repairing concrete and a preparation method, so that the concrete can undergo multi-cycle, reciprocating, continuous and gradual damage repair until the source of damage is completely blocked. Summary of the invention

[0008] The purpose of the present invention is to provide a bacterial agent separation dual system self-repairing concrete and a preparation method, so as to solve the problem that the bacterial agent cannot be consumed once in the concrete self-repair process to achieve reliable repair, improve the durability of concrete structures under freeze-thaw cycles, and greatly extend the service life of concrete in extreme environments.

[0009] To achieve the above object, the present invention provides the following technical solutions:

[0010] A bacterial agent separation dual-system self-repairing concrete comprises the following raw materials in weight fractions: 1100-1300 parts of coarse aggregate, 500-560 parts of river sand, 30-40 parts of silica fume, 300-425 parts of ordinary Portland cement (PO 42.5), 5-6 parts of water reducer, 90-120 parts of a carrier carrying uniformly distributed microorganisms, and 240-260 parts of a slow-release carrier carrying nutrients, wherein the slow-release carrier comprises large-diameter porous particles, and a protective layer is arranged outside the large-diameter porous particles; the microorganisms are Bacillus cohnii and denitrifying bacteria.

[0011] Preferably, the microbial carrier is a hollow fiber, or a sisal fiber, or a high-strength Tena graphene fiber, or a small-particle expanded perlite.

[0012] Preferably, the large-size porous particles include large-size perlite and large-size expanded perlite, the perlite particle size is 1.0mm-3.2mm, and the protective layer outside the large-size porous particles is potassium magnesium phosphate cement, or a slurry obtained by mixing sodium acid solution with kaolin and water in proportion.

[0013] Preferably, the small-size expanded perlite is provided with a potassium magnesium phosphate cement protective layer.

[0014] Preferably, the ingredients and proportions of the Bacillus cohnii nutrient are: 1000-1200 parts of expanded perlite, 750-900 parts of potassium dihydrogen phosphate, 2200-2300 parts of magnesium oxide, 40-50 parts of anhydrous sodium acetate, 1350-1400 parts of water, 10-13 parts of inosine, 220-230 parts of sodium dihydrogen phosphate, 4.5-5.6 parts of beef extract, 7.5-8 parts of peptone, and 135 parts of calcium lactate.

[0015] Preferably, the composition and proportion of the denitrifying bacteria nutrient are: 1000-1200 parts of expanded perlite, 750-900 parts of potassium dihydrogen phosphate, 2200-2300 parts of magnesium oxide, 40-50 parts of anhydrous sodium acetate, 2200-2350 parts of water, 5 parts of yeast extract powder, 10-10.2 parts of peptone, and 75-89 parts of calcium nitrate.

[0016] A method for preparing a bacterial agent separation dual system self-repairing concrete, which is applied to the bacterial agent separation dual system self-repairing concrete, comprises the following steps:

[0017] S1: centrifuging the culture medium containing microorganisms and washing with deionized water, refrigerating the washed bacterial solution for later use, and filling the bacterial solution into the carrier by vacuum adsorption method to obtain a carrier carrying uniformly distributed microorganisms;

[0018] S2: preparing a nutrient solution of microorganisms, selecting a slow-release carrier, adsorbing the nutrient solution into the slow-release carrier by a vacuum adsorption method, and coating the carrier with a protective layer material to obtain a slow-release carrier loaded with nutrients;

[0019] S3: 90-120 parts of the carrier loaded with uniformly distributed microorganisms are premixed with 2-3 parts of a water reducer and dispersed by ultrasonication to obtain a carrier dispersion;

[0020] S4: Mix the raw materials according to 1100-1300 parts of coarse aggregate, 500-560 parts of river sand, 30-40 parts of silica fume, 300-425 parts of ordinary Portland cement (P.O42.5), and 2-3 parts of water reducer, and then add 240-260 parts of slow-release carrier containing nutrients and carrier dispersion and continue to stir. After stirring evenly, put it into the mold for curing.

[0021] Preferably, the preparation process of the carrier containing uniformly distributed microorganisms is as follows: Bacillus cohnii and denitrifying bacteria are prepared into Bacillus cohnii spore suspension and denitrifying bacteria suspension, hollow fiber, sisal fiber, high-strength Tena graphene fiber, or small-particle expanded perlite is selected as the strain carrier, and the carrier is placed in a vacuum cylinder for vacuum adsorption and then vibrated and dispersed, and dried at 40±2°C to constant weight.

[0022] Preferably, the preparation process of the sustained-release carrier loaded with nutrients is: selecting nutrients of Bacillus cohnii and denitrifying bacteria to form a nutrient solution, and placing the nutrient solution and large-size porous particles into a vacuum cylinder for vacuum adsorption and then vibration dispersion, drying at 40±2°C to constant weight, and evenly mixing the protective layer solution, and drying and hardening.

[0023] Preferably, the self-repairing concrete mixing preparation process is: first premix the bacteria-carrying carrier and the water reducer and disperse them evenly by ultrasound to obtain a dispersion, mix the remaining raw materials evenly according to the mix ratio, add the slow-release carrier containing nutrients and the carrier dispersion and continue stirring for 60 seconds, and then mold and cure to form.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] The present invention provides a bacterial agent separation dual-system self-repairing concrete and a preparation method thereof, which adopts aerobic and anaerobic microbial co-mixing for mineralization, such as the synergistic effect of Bacillus cohnii and denitrifying bacteria. Bacillus cohnii and denitrifying bacteria use aerobic Bacillus cohnii with extremely fast mineralization rate to repair cracks, and use the continuous and slow mineralization of denitrifying bacteria in an anaerobic environment to squeeze the retained water in the cracks out of the cracks, so as to achieve delayed and efficient repair of long cracks after the cracks are closed, improve the repair density, compress the water storage space in the cracks, inhibit freeze-thaw damage, and avoid the accumulation of mineralized products at the cracks on the surface of concrete; and Bacillus cohnii and denitrifying bacteria are domesticated in a long-term engineering freeze-thaw environment simulation, and the rapid freezing and thawing method is used to improve the response rate of the bacteria, which is suitable for fast-response bacteria that repeatedly dormant and awakened in multiple cycles, and a self-repairing operation mechanism that conforms to the evolution characteristics of freeze-thaw damage is established, which can realize the self-repair of periodic crack damage caused by periodic freeze-thaw cycles in concrete.

[0026] The present invention provides a bacterial agent separation dual-system self-repairing concrete and a preparation method thereof. The self-repairing concrete adopts large-size perlite with a hollow structure, a porous interior and strong hydrophilicity to fix slow-release nutrients. The carrier of the nutrients utilizes the slow-release principle to quantitatively release nutrients, and the nutrient release rate is adjusted by changing the ratio of the slow-release agent, so that the nutrients can be supplied and consumed within several freeze-thaw cycles. The self-repairing concrete adopts porous particles such as highly water-absorbent fiber filaments or small-size perlite to fix microorganisms, so as to realize point-by-point synchronous repair of microorganisms in concrete cracks. Nutrients are transported to each microbial growth point through the migration of water media, and a "self-sensing-self-awakening-self-sleeping" type cyclic healing dynamic mechanism is constructed, so that the mineralized products gradually fill the crack space.

[0027] The present invention provides a bacterial agent separation dual system self-repairing concrete and a preparation method thereof. Perlite can form a shear fault zone in the concrete, inducing cracks to move toward the zone, which can release the stress at the crack tip, inhibit the rapid expansion of a single crack driven by frost heave force, reduce the risk of freeze-thaw damage, and promptly awaken and start the self-repairing mechanism. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 A schematic diagram of a material for preparing a bacterial agent separation dual system self-repairing concrete according to the present invention;

[0029] Figure 2 This is a schematic diagram of a self-repairing process of a bacterial agent separation dual system self-repairing concrete according to the first embodiment of the present invention;

[0030] Figure 3 This is a schematic diagram of the self-repairing process of a bacterial agent separation dual system self-repairing concrete described in Example 2 of the present invention.

[0031] Reference numerals:

[0032] 1. Hollow fiber bacteria carrier; 2. Large-size perlite nutrient slow-release carrier; 3. Microorganisms; 4. Nutrient one; 5. Mineralization product; 6. Fracture water; 7. Small-size expanded perlite bacteria carrier; 8. Large-size expanded perlite nutrient slow-release carrier; 9. Nutrient two. DETAILED DESCRIPTION

[0033] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0034] In the following description of the invention, it should be noted that the terms "upper", "lower", "left", "right", "inner", "outer", etc., indicating directions or positional relationships, are based on directions or positional relationships shown in the drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a specific direction or be constructed and operated in a specific direction. The term "connection" only indicates the connection between devices and has no special meaning.

[0035] In addition, the technical fields and installation methods involved in the embodiments of the present invention described below can be combined with each other as long as there is no conflict between them.

[0036] Specific implementation: Please refer to Figure 1 A bacterial agent separation dual system self-repairing concrete includes a slow-release carrier carrying uniformly distributed microbial carriers and nutrients, the microbial carriers store fast-response bacteria suitable for multi-cycle repeated dormancy-awakening, the slow-release carriers include porous particles such as perlite with large particle size (1.0mm-3.2mm) and a protective layer on the outside, and the slow-release carriers store nutrients for aerobic and anaerobic microorganisms.

[0037] Specifically, the carrier carrying uniformly distributed microorganisms is a highly water-absorbent fiber with sealed ends, such as polyester fiber, alkali-resistant glass fiber, hollow silver-loaded polyester fiber, sisal fiber, bamboo fiber, spandex fiber, high-strength Tena graphene fiber, hollow fiber, etc., or small-diameter (0.3mm-1.0mm) porous particles such as perlite, pumice, coral stone, etc. with a protective layer on the outside.

[0038] Among them, the fast-responding bacteria with multiple cycles of repeated dormancy and awakening use Bacillus cohnii and denitrifying bacteria. Bacillus cohnii and denitrifying bacteria are domesticated for a long time, and the domestication environment simulates the real engineering freeze-thaw environment. The rapid freezing and rapid thawing method is used to improve the response rate of the bacteria. They are suitable for fast-responding bacteria with multiple cycles of repeated dormancy and awakening. They can quickly transform into spore form during the dormancy period, and use the spore wall to protect the bacteria.

[0039] Under the action of frost heave, the repaired cracks will crack again and connect with the external environment. At this time, driven by the crack expansion force, the nutrients released by the slow-release carrier particles carrying nutrients and the water-oxygen environment can quickly stimulate the activity of aerobic Bacillus cohnii and achieve rapid mineralization repair. Especially near the cracks, due to the enrichment of water-oxygen, the mineralization speed is extremely fast. The mineralized products quickly block the connected cracks and isolate them from the external environment. The synergy of Bacillus cohnii and denitrifying bacteria is adopted, and the aerobic Bacillus cohnii with extremely fast mineralization rate is used to repair the cracks, and the continuous slow mineralization of denitrifying bacteria in an anaerobic environment is used to squeeze out the retained water in the cracks.

[0040] Specifically, the sustained-release carrier loaded with nutrients utilizes the sustained-release principle to quantitatively release the nutrients, and adjusts the nutrient release rate by changing the ratio of the sustained-release agent to avoid the consumption of the nutrients in one or several freeze-thaw cycles.

[0041] Specifically, a method for preparing a bacterial agent separation dual system self-repairing concrete is as follows:

[0042] S1: centrifuging the culture medium containing microorganisms and washing with deionized water, refrigerating the washed bacterial solution for later use, and filling the bacterial solution into the carrier by vacuum adsorption method to obtain a carrier carrying uniformly distributed microorganisms;

[0043] S2: preparing a nutrient solution of microorganisms, selecting a slow-release carrier, adsorbing the nutrient solution into the slow-release carrier by a vacuum adsorption method, and coating the carrier with a protective layer material to obtain a slow-release carrier loaded with nutrients;

[0044] S3: 90-120 parts of the carrier loaded with uniformly distributed microorganisms are premixed with 2-3 parts of a water reducer and dispersed by ultrasonication to obtain a carrier dispersion;

[0045] S4: Mix the raw materials in the proportion of 1100-1300 parts of coarse aggregate, 500-560 parts of river sand, 30-40 parts of silica fume, 300-425 parts of ordinary Portland cement (PO 42.5), and 2-3 parts of water reducer, then add 240-260 parts of slow-release carrier containing nutrients and the above-mentioned carrier dispersion and continue to stir. After stirring evenly, put it into a mold for curing.

[0046] Example 1: In this example, the microorganism carrier is specifically hollow fiber, and the nutrient carrier is specifically large-diameter expanded perlite;

[0047] The present embodiment provides a bacterial agent separation dual system self-repairing concrete, which includes the following raw materials: 1200 parts of coarse aggregate, 500 parts of river sand, 35 parts of silica fume, 400 parts of ordinary Portland cement (PO 42.5), 6 parts of water reducer, 120 parts of hollow fiber carriers carrying uniformly distributed microorganisms, and 250 parts of large-particle expanded perlite slow-release carriers carrying nutrients.

[0048] The specific steps for preparing the hollow fiber carrier carrying microorganisms are as follows:

[0049] S11-1: Select Bacillus cohnii and denitrifying bacteria.

[0050] S12-1: Preparation of Bacillus cohnii spore suspension:

[0051] Inoculate 1% of the inoculum into the optimal spore-forming culture medium, ferment and culture under optimal external conditions for 4 days to obtain a spore-containing culture medium liquid, then divide 5 ml of the spore-containing culture medium liquid into 100 ml centrifuge tubes, centrifuge at 5000 rpm, 4°C for 5 min, repeatedly centrifuge and wash three times with deionized water, resuspend in deionized water, and obtain a spore suspension and place it in a 4°C refrigerator for use.

[0052] S13-1: Prepare a denitrifying bacteria suspension in the same manner as that of Bacillus cohnii spore suspension.

[0053] S14-1: PET hollow fiber was selected as the strain carrier. The axis of the fiber had a through tubular cavity with a hollow ratio of 55%.

[0054] S15-1: Place the hollow fiber filaments in a vacuum barrel, start the vacuum pump and stop when the vacuum degree reaches -0.006MPa, then suck the prepared Bacillus cohnii spore suspension and denitrifying bacteria suspension into the vacuum cylinder through the pressure relief ball valve under negative pressure, wait until the Bacillus cohnii spore suspension and the denitrifying bacteria suspension all flow into the vacuum cylinder, close the pressure relief ball valve, and after the vacuum adsorption reaches the specified time, obtain the hollow fiber carrier fiber filaments carrying microorganisms, and place it in a 50℃ drying oven and heat it for 25s to shrink the fiber filament seal; after the adsorption is completed, filter with a sieve to remove excess bacterial liquid, and then place it in an oven to dry to constant weight to obtain a hollow fiber carrier carrying microorganisms.

[0055] The above-mentioned large-particle expanded perlite slow-release carrier containing nutrients is prepared by the following specific steps:

[0056] S21-1: A nutrient solution for Bacillus cohnii is prepared by dissolving 1000 parts of expanded perlite, 812 parts of potassium dihydrogen phosphate, 2200 parts of magnesium oxide, 45 parts of anhydrous sodium acetate, 1380 parts of water, 12 parts of inosine, 223 parts of sodium dihydrogen phosphate, 5.6 parts of beef extract, 7.8 parts of peptone, and 135 parts of calcium lactate; a nutrient solution for denitrifying bacteria is prepared by dissolving 1000 parts of expanded perlite, 812 parts of potassium dihydrogen phosphate, 2200 parts of magnesium oxide, 45 parts of anhydrous sodium acetate, 2213 parts of water, 5 parts of yeast extract powder, 10.2 parts of peptone, and 89 parts of calcium nitrate.

[0057] S22-1: Select an appropriate amount of large-size expanded perlite and place it into a vacuum cylinder with the prepared nutrient solution of Bacillus coli and the nutrient solution of denitrifying bacteria. After vacuum adsorption (the whole operation process is controlled within about 10 minutes), disperse it by vibration and dry it in a 40℃±2℃ forced air drying oven to constant weight.

[0058] S23-1: Potassium magnesium phosphate cement prepared by mixing potassium dihydrogen phosphate and magnesium oxide with water in a certain proportion is used as the protective layer solution for large-particle expanded perlite.

[0059] S24-1: Place the dried large-particle perlite loaded with nutrients into a drum mixer, then pour the prepared protective layer solution into a high-pressure spray pot, turn on the air compressor and the mixer, and evenly spray the protective layer solution on the surface of the large-particle expanded perlite. After drying and hardening, a large-particle expanded perlite slow-release carrier loaded with nutrients is obtained.

[0060] Finally, the prepared hollow fiber carrier carrying evenly distributed microorganisms and the large-particle perlite slow-release carrier carrying nutrients are mixed and stirred, poured into a mold for curing and forming, and the self-repairing concrete is obtained.

[0061] Among them, before mixing and preparing the self-repairing concrete, 120 parts of hollow fiber carriers carrying uniformly distributed microorganisms are premixed with 3 parts of water reducers and dispersed by ultrasound to make them evenly dispersed and obtain a fiber dispersion of the hollow fiber. The remaining raw materials are evenly mixed according to 1200 parts of coarse aggregate, 500 parts of river sand, 35 parts of silica fume, 400 parts of ordinary Portland cement (PO 42.5), and 3 parts of water reducers. Then, 250 parts of large-particle perlite slow-release carriers carrying nutrients and the above-mentioned fiber dispersion are added and stirred for 60 seconds, and the self-repairing concrete is obtained by mold curing.

[0062] Example 2: In this example, the microorganism carrier is small-size perlite, and the nutrient carrier is specifically large-size perlite;

[0063] The present embodiment provides a bacterial agent separation dual system self-repairing concrete, comprising the following raw materials: 1200 parts of coarse aggregate, 500 parts of river sand, 35 parts of silica fume, 400 parts of ordinary Portland cement (PO 42.5), 6 parts of water reducer, 120 parts of small-particle perlite carrier carrying uniformly distributed microorganisms, and 250 parts of large-particle perlite slow-release carrier carrying nutrients.

[0064] The specific steps for preparing the above-mentioned small-size perlite carrier carrying uniformly distributed microorganisms are as follows:

[0065] S11-2: Select Bacillus cohnii and denitrifying bacteria.

[0066] S11-2: Preparation of Bacillus cohnii spore suspension:

[0067] Inoculate 1% of the inoculum into the optimal spore-forming culture medium, ferment and culture under optimal external conditions for 4 days to obtain a spore-containing culture medium liquid, then divide 5 ml of the spore-containing culture medium liquid into 100 ml centrifuge tubes, centrifuge at 5000 rpm, 4°C for 6 min, repeatedly centrifuge and wash three times with deionized water, resuspend in deionized water, and obtain a spore suspension and place it in a 4°C refrigerator for use.

[0068] S13-2: Prepare a denitrifying bacteria suspension in the same manner as that of Bacillus cohnii spore suspension.

[0069] S14-2: Small-sized perlite was used as the strain carrier.

[0070] S15-2: Place the prepared Bacillus cohnii spore suspension and denitrifying bacteria suspension and small-particle expanded perlite into a vacuum cylinder for vacuum adsorption (the entire operation process is controlled within about 10 minutes), then disperse by vibration, and dry in a 40℃±2℃ forced air drying oven to constant weight to obtain a small-particle expanded perlite carrier carrying uniformly distributed microorganisms.

[0071] S16-2: Potassium magnesium phosphate cement prepared by potassium dihydrogen phosphate and magnesium oxide in a certain proportion with water is used as a protective layer solution for a small-particle expanded perlite carrier carrying uniformly distributed microorganisms.

[0072] S17-2: Place the dried small-particle expanded perlite carrier carrying evenly distributed microorganisms into a drum mixer, then pour the prepared protective layer solution into a high-pressure spray pot, turn on the air compressor and the mixer, and evenly spray the protective layer solution on the surface of the small-particle expanded perlite. After drying and hardening, the small-particle expanded perlite carrier carrying evenly distributed microorganisms is obtained.

[0073] Different from Example 1, the large-size perlite as the slow-release carrier carrying nutrients in this example is prepared in step S23-2: a slurry obtained by mixing sodium silicate solution: metakaolin: water = 1.0:2.2:1.1 is used as a protective layer material for the large-size perlite.

[0074] Finally, the prepared small-particle expanded perlite carrier carrying evenly distributed microorganisms and the large-particle perlite slow-release carrier carrying nutrients are mixed, stirred evenly, and poured into a mold for curing and forming, thereby obtaining the self-repairing concrete.

[0075] The specific mixing and preparation process of this embodiment is the same as that of Embodiment 1, except that the microbial carrier and the slow-release carrier of the nutrient substance are different. Before mixing and preparing the self-repairing concrete, 120 parts of the prepared small-particle expanded perlite carrier carrying uniformly distributed microorganisms are premixed with 3 parts of a water reducer and dispersed evenly by ultrasonic wave to obtain a dispersion. Then, the remaining raw materials are evenly stirred, 250 parts of the large-particle perlite slow-release carrier carrying the nutrient substance and the above dispersion are added, and stirring is continued for 60 seconds, and the self-repairing concrete is obtained by molding and curing.

[0076] Example 3: In this example, the microbial carrier is sisal fiber, and the sustained-release carrier of nutrients is specifically large-particle expanded perlite;

[0077] The present embodiment provides a bacterial agent separation dual system self-repairing concrete, which includes the following raw materials: 1300 parts of coarse aggregate, 560 parts of river sand, 40 parts of silica fume, 425 parts of ordinary Portland cement (PO 42.5), 5.6 parts of water reducer, 120 parts of sisal fiber carrier carrying uniformly distributed microorganisms, and 240 parts of large-particle expanded perlite slow-release carrier carrying nutrients.

[0078] The preparation of the sisal fiber carrier carrying uniformly distributed microorganisms is carried out in the following specific steps:

[0079] S11-3: Select Bacillus cohnii and denitrifying bacteria.

[0080] S12-3: Preparation of Bacillus cohnii spore suspension:

[0081] Inoculate 1% of the inoculum into the optimal spore-forming medium containing agar, peptone, beef extract, KCl, and distilled water, ferment and culture under optimal external conditions for 4 days to obtain 5 ml of spore-containing medium liquid, then divide the 5 ml of spore-containing medium liquid into 100 ml centrifuge tubes, centrifuge at 5000 rpm and 4°C for 7 min, repeatedly centrifuge and wash three times with deionized water, resuspend in deionized water, and obtain a spore suspension and place it in a 4°C refrigerator for standby use.

[0082] S13-3: Prepare a denitrifying bacteria suspension in the same manner as that of Bacillus cohnii spore suspension.

[0083] S14-3: Sisal fiber was selected as the strain carrier.

[0084] S15-3: Place sisal fiber in a vacuum barrel, start the vacuum pump until the vacuum degree reaches -0.006MPa and stop, then suck the prepared Bacillus cohnii spore suspension and denitrifying bacteria suspension into the vacuum cylinder through the pressure relief ball valve under negative pressure, wait until the Bacillus cohnii spore suspension and the denitrifying bacteria suspension all flow into the vacuum cylinder, close the pressure relief ball valve, and after the vacuum adsorption reaches the specified time, obtain the sisal fiber carrier fiber filaments carrying uniformly distributed microorganisms, and place it in a 50°C drying oven and heat it for 25s; after the adsorption is completed, filter with a sieve to remove excess bacterial liquid, and then place it in an oven to dry to constant weight to obtain the sisal fiber carrier carrying uniformly distributed microorganisms.

[0085] The specific steps for preparing the above-mentioned large-particle expanded perlite slow-release carrier containing nutrients are as follows:

[0086] S21-3: A nutrient solution for Bacillus cohnii is prepared by dissolving 1120 parts of expanded perlite, 750 parts of potassium dihydrogen phosphate, 2300 parts of magnesium oxide, 40 parts of anhydrous sodium acetate, 1350 parts of water, 10 parts of inosine, 220 parts of sodium dihydrogen phosphate, 4.5 parts of beef extract, 7.5 parts of peptone, and 135 parts of calcium lactate; a nutrient solution for denitrifying bacteria is prepared by dissolving 1120 parts of expanded perlite, 750 parts of potassium dihydrogen phosphate, 2300 parts of magnesium oxide, 40 parts of anhydrous sodium acetate, 2350 parts of water, 5 parts of yeast extract powder, 10 parts of peptone, and 75 parts of calcium nitrate.

[0087] S22-3: Select an appropriate amount of large-size expanded perlite and place it into a vacuum cylinder together with the prepared nutrient solution of Bacillus cohnii and the nutrient solution of denitrifying bacteria. Perform vacuum adsorption (the entire operation process is controlled within about 10 minutes) and then vibrate to disperse. Place the mixture in a 40±2℃ forced air drying oven and dry to constant weight.

[0088] S23-3: A slurry obtained by mixing sodium silicate solution: metakaolin: water = 1.0:2.2:1.1 is used as a protective layer solution for large-particle expanded perlite.

[0089] S24-3: Place the dried large-particle expanded perlite loaded with nutrients into a drum mixer, then pour the prepared protective layer solution into a high-pressure spray pot, turn on the air compressor and the mixer, and evenly spray the protective layer solution on the surface of the large-particle expanded perlite. After drying and hardening, a large-particle expanded perlite slow-release carrier loaded with nutrients is obtained.

[0090] Finally, the prepared sisal fiber carrier carrying evenly distributed microorganisms and the large-particle expanded perlite slow-release carrier carrying nutrients are mixed, stirred evenly, and poured into a mold for curing and forming, thereby obtaining the self-repairing concrete.

[0091] The specific mixing preparation process of this embodiment is the same as that of Embodiment 1, except that the microbial carrier and the slow-release carrier of the nutrient substance are different, and before mixing to prepare the self-repairing concrete, 120 parts of the prepared sisal fiber carrier carrying evenly distributed microorganisms are premixed with 3 parts of a water reducer and dispersed evenly by ultrasound to obtain a dispersion, and then the remaining raw materials are stirred evenly, and then 240 parts of a large-particle perlite slow-release carrier carrying nutrients and the above-mentioned dispersion are added and stirred for 60 seconds, and molded and cured to obtain the self-repairing concrete.

[0092] Example 4: The microbial carrier in this example is high-strength Turner graphene fiber, and the nutrient carrier is specifically large-particle expanded perlite;

[0093] The present embodiment provides a bacterial agent separation dual system self-repairing concrete, comprising the following raw materials: 1100 parts of coarse aggregate, 500 parts of river sand, 30 parts of silica fume, 300 parts of ordinary Portland cement (PO 42.5), 5 parts of water reducer, 90 parts of high-strength Turner graphene fiber loaded with microorganisms, and 260 parts of large-particle expanded perlite loaded with nutrients.

[0094] The specific steps for preparing the high-strength Turner graphene fiber carrier carrying uniformly distributed microorganisms are as follows:

[0095] S11-4: Select Bacillus cohnii and denitrifying bacteria.

[0096] S12-4: Preparation of Bacillus cohnii spore suspension:

[0097] Inoculate 1% of the inoculum into the optimal spore-forming culture medium, ferment and culture under optimal external conditions for 4 days to obtain a spore-containing culture medium liquid, then divide 5 ml of the spore-containing culture medium liquid into 100 ml centrifuge tubes, centrifuge at 5000 rpm, 4°C for 6 min, repeatedly centrifuge and wash three times with deionized water, resuspend in deionized water, and obtain a spore suspension and place it in a 4°C refrigerator for use.

[0098] S13-4: Prepare a denitrifying bacteria suspension in the same manner as that of Bacillus cohnii spore suspension.

[0099] S14-4: High-strength Turner graphene fiber was selected as the strain carrier.

[0100] S15-4: Place the high-strength Turner graphene fiber in a vacuum barrel, start the vacuum pump and stop when the vacuum degree reaches -0.006MPa, then suck the prepared Bacillus spore suspension and denitrifying bacteria suspension into the vacuum cylinder through the pressure relief ball valve under negative pressure, wait until the Bacillus spore suspension and the denitrifying bacteria suspension all flow into the vacuum cylinder, close the pressure relief ball valve, and after the vacuum adsorption reaches the specified time, obtain the high-strength Turner graphene fiber carrier fiber filaments carrying uniformly distributed microorganisms, and place it in a 50℃ drying oven for heating for 25s; after the adsorption is completed, filter with a sieve to remove excess bacterial liquid, and then place it in an oven and dry it to constant weight to obtain a high-strength Turner graphene fiber carrier carrying uniformly distributed microorganisms.

[0101] Different from Example 3, in the preparation of the large-particle perlite sustained-release carrier loaded with nutrients in this example, step S21-4 uses 1200 parts of expanded perlite, 900 parts of potassium dihydrogen phosphate, 2300 parts of magnesium oxide, 50 parts of anhydrous sodium acetate, 1400 parts of water, 13 parts of inosine, 230 parts of sodium dihydrogen phosphate, 5.5 parts of beef extract, 8 parts of peptone, and 135 parts of calcium lactate to mix and dissolve to prepare a nutrient solution for Bacillus cohnii; 1200 parts of expanded perlite, 900 parts of potassium dihydrogen phosphate, 2300 parts of magnesium oxide, 50 parts of anhydrous sodium acetate, 2200 parts of water, 5 parts of yeast extract powder, 10 parts of peptone, and 80 parts of calcium nitrate are mixed and dissolved to prepare a nutrient solution for denitrifying bacteria.

[0102] Finally, the prepared high-strength Turner graphene fiber carrier carrying evenly distributed microorganisms and the large-particle perlite slow-release carrier carrying nutrients are mixed, stirred evenly, and poured into a mold for curing and forming to obtain the self-repairing concrete.

[0103] The specific mixing and preparation process of this embodiment is the same as that of Embodiment 1, except that the microbial carrier and the slow-release carrier of the nutrient substance are different, and before mixing and preparing the self-repairing concrete, 90 parts of the prepared high-strength Turner graphene fiber carrier carrying uniformly distributed microorganisms are premixed with 2 parts of a water reducer and dispersed evenly by ultrasonic wave to obtain a dispersion, and then the remaining raw materials are stirred evenly, and then 260 parts of a large-particle perlite slow-release carrier carrying nutrients and the above-mentioned dispersion are added and stirred for 60 seconds, and molded and cured to obtain the self-repairing concrete.

[0104] See also Figure 2, the repair process of the self-repairing concrete provided in Example 1 is as follows: when the concrete is subjected to freeze-thaw damage and cracks are generated for the first time, the hollow fiber bacteria carrier 1 carrying microorganisms 3 and the large-size perlite nutrient slow-release carrier 2 carrying microbial nutrients 1 4 are damaged during the continuous extension of the cracks, and the microorganisms 3 and nutrients 1 4 are released respectively, and the fissure water 6 transports the nutrients 4 to the cracks, and the microorganisms 3 contact the nutrients 4 to release the mineralized products 5, which can repair the freeze-thaw damage cracks of the concrete at all damaged parts at the same time. The repaired concrete can continue to act on the freeze-thaw environment, and the bacteria enter the "self-dormancy" mode at this time. When the concrete is damaged again, the microorganisms 3 and nutrients 4 are released and contacted again, and the self-repair mode is turned on again inside the concrete to complete the repair of the concrete structure; this cycle is repeated until the self-repairing concrete structure loses its durability.

[0105] See also Figure 3 The repair process of the self-repairing concrete provided in Example 2 is as follows: when the concrete is subjected to freeze-thaw damage under the action of freeze-thaw cycles and cracks are generated for the first time inside, the small-sized expanded perlite bacteria-carrying microorganisms 3 and the large-sized expanded perlite nutrient slow-release carrier 8 carrying microbial nutrients 9 are damaged during the continuous extension of the cracks, and the microorganisms 3 and the nutrients 9 are released respectively, and the fissure water 6 transports the nutrients 9 to the cracks, and the microorganisms 3 contact the nutrients 9 to release mineralized products 5, which can repair the freeze-thaw damage cracks of the concrete at all damaged parts at the same time. The repaired concrete can continue to act in the freeze-thaw environment, and the bacteria enter the "self-dormancy" mode at this time; the cycle is repeated until the self-repairing concrete structure loses its durability.

[0106] The present invention provides a bacterial agent separation dual-system self-repairing concrete and a preparation method thereof, which adopts aerobic and anaerobic microbial co-mixing for mineralization, such as the synergistic effect of Bacillus cohnii and denitrifying bacteria. Bacillus cohnii and denitrifying bacteria use aerobic Bacillus cohnii with extremely fast mineralization rate to repair cracks, and use the continuous and slow mineralization of denitrifying bacteria in an anaerobic environment to squeeze the retained water in the cracks out of the cracks, so as to achieve delayed and efficient repair of long cracks after the cracks are closed, improve the repair density, compress the water storage space in the cracks, inhibit freeze-thaw damage, and avoid the accumulation of mineralized products at the cracks on the surface of concrete; and Bacillus cohnii and denitrifying bacteria are domesticated in a long-term engineering freeze-thaw environment simulation, and the rapid freezing and thawing method is used to improve the response rate of the bacteria, which is suitable for fast-response bacteria that repeatedly dormant and awakened in multiple cycles, and a self-repairing operation mechanism that conforms to the evolution characteristics of freeze-thaw damage is established, which can realize the self-repair of periodic crack damage caused by periodic freeze-thaw cycles in concrete.

[0107] The present invention provides a bacterial agent separation dual-system self-repairing concrete and a preparation method thereof. The self-repairing concrete adopts large-size perlite with a hollow structure, a porous interior and strong hydrophilicity to fix slow-release nutrients. The carrier of the nutrients utilizes the slow-release principle to quantitatively release nutrients, and the nutrient release rate is adjusted by changing the ratio of the slow-release agent, so that the nutrients can be supplied and consumed within several freeze-thaw cycles. The self-repairing concrete adopts porous particles such as highly water-absorbent fiber filaments or small-size perlite to fix microorganisms, so as to realize point-by-point synchronous repair of microorganisms in concrete cracks. Nutrients are transported to each microbial growth point through the migration of water media, and a "self-sensing-self-awakening-self-sleeping" type cyclic healing dynamic mechanism is constructed, so that the mineralized products gradually fill the crack space.

[0108] The present invention provides a bacterial agent separation dual system self-repairing concrete and a preparation method thereof. Perlite can form a shear fault zone in the concrete, inducing cracks to move toward the zone, which can release the stress at the crack tip, inhibit the rapid expansion of a single crack driven by frost heave force, reduce the risk of freeze-thaw damage, and promptly awaken and start the self-repairing mechanism.

Claims

1. A bacterial agent separation dual system self-repairing concrete, Features: The invention comprises the following raw materials in weight fractions: 1100-1300 parts of coarse aggregate, 500-560 parts of river sand, 30-40 parts of silica fume, 300-425 parts of ordinary Portland cement (PO 42.5), 5-6 parts of water reducer, 90-120 parts of a carrier carrying uniformly distributed microorganisms, and 240-260 parts of a slow-release carrier carrying nutrients, wherein the slow-release carrier comprises large-diameter porous particles, and a protective layer is arranged outside the large-diameter porous particles; the microorganisms are Bacillus cohnii and denitrifying bacteria.

2. The bacterial agent separation dual system self-repairing concrete according to claim 1, Features: The microbial carrier is hollow fiber, or sisal fiber, or high-strength Turner graphene fiber, or small-diameter expanded perlite.

3. The bacterial agent separation dual system self-repairing concrete according to claim 1, Features: The large-size porous particles include large-size perlite and large-size expanded perlite. The perlite particle size is 1.0mm-3.2mm. The protective layer outside the large-size porous particles is potassium magnesium phosphate cement, or a slurry obtained by mixing sodium acid solution with kaolin and water in proportion.

4. The bacterial agent separation dual system self-repairing concrete according to claim 2, Features: A potassium magnesium phosphate cement protective layer is arranged outside the small-size expanded perlite.

5. The bacterial agent separation dual system self-repairing concrete according to claim 1, Features: The ingredients and proportions of the nutrient material for Bacillus cohnii are: 1000-1200 parts of expanded perlite, 750-900 parts of potassium dihydrogen phosphate, 2200-2300 parts of magnesium oxide, 40-50 parts of anhydrous sodium acetate, 1350-1400 parts of water, 10-13 parts of inosine, 220-230 parts of sodium dihydrogen phosphate, 4.5-5.6 parts of beef extract, 7.5-8 parts of peptone, and 135 parts of calcium lactate.

6. The bacterial agent separation dual system self-repairing concrete according to claim 1, Features: The composition and proportion of the denitrifying bacteria nutrient are: 1000-1200 parts of expanded perlite, 750-900 parts of potassium dihydrogen phosphate, 2200-2300 parts of magnesium oxide, 40-50 parts of anhydrous sodium acetate, 2200-2350 parts of water, 5 parts of yeast extract powder, 10-10.2 parts of peptone, and 75-89 parts of calcium nitrate.

7. A method for preparing a bacterial agent separation dual system self-repairing concrete, applied to the bacterial agent separation dual system self-repairing concrete according to any one of claims 1 to 6, It is characterized in that The steps include: S1: centrifuging the culture medium containing microorganisms and washing with deionized water, refrigerating the washed bacterial solution for later use, and filling the bacterial solution into the carrier by vacuum adsorption method to obtain a carrier carrying uniformly distributed microorganisms; S2: preparing a nutrient solution of microorganisms, selecting a slow-release carrier, adsorbing the nutrient solution into the slow-release carrier by a vacuum adsorption method, and coating the carrier with a protective layer material to obtain a slow-release carrier loaded with nutrients; S3: 90-120 parts of the carrier loaded with uniformly distributed microorganisms are premixed with 2-3 parts of a water reducer and dispersed by ultrasonication to obtain a carrier dispersion; S4: Mix the raw materials according to 1100-1300 parts of coarse aggregate, 500-560 parts of river sand, 30-40 parts of silica fume, 300-425 parts of ordinary Portland cement (PO 42.5), and 2-3 parts of water reducer, and then add 240-260 parts of slow-release carrier containing nutrients and carrier dispersion and continue to stir. After stirring evenly, put it into a mold for curing.

8. The method for preparing a bacterial agent separation dual system self-repairing concrete according to claim 7, Features: The preparation process of the microbial carrier with uniform distribution is as follows: Bacillus cohnii and denitrifying bacteria are prepared into Bacillus cohnii spore suspension and denitrifying bacteria suspension, hollow fiber, sisal fiber, high-strength Tena graphene fiber, or small-size expanded perlite is selected as the strain carrier, and the carrier is placed in a vacuum cylinder for vacuum adsorption and then vibrated and dispersed, and dried at 40±2°C to constant weight.

9. The method for preparing a bacterial agent separation dual system self-repairing concrete according to claim 7, Features: The preparation process of the sustained-release carrier loaded with nutrients is as follows: nutrients of Bacillus cohnii and denitrifying bacteria are selected to form a nutrient solution, and the nutrient solution and large-size porous particles are placed in a vacuum cylinder for vacuum adsorption and then dispersed by vibration, dried at 40±2° C. to constant weight, and evenly mixed with a protective layer solution, and dried to harden.

10. The method for preparing a bacterial agent separation dual system self-repairing concrete according to claim 7, Features: The self-repairing concrete mixing preparation process is: first premix the bacteria carrier and the water reducer and disperse them evenly by ultrasonic to obtain a dispersion, mix the remaining raw materials evenly according to the mix ratio, add the slow-release carrier containing nutrients and the carrier dispersion, continue to stir for 60 seconds, and mold and cure to form.

Images