CN111056799B - Hydrogel-encapsulated bacterial spore self-repairing material with pH responsiveness and cement-based concrete self-repairing method - Google Patents
Hydrogel-encapsulated bacterial spore self-repairing material with pH responsiveness and cement-based concrete self-repairing method Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/34—Non-shrinking or non-cracking materials
- C04B2111/343—Crack resistant materials
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Abstract
The invention belongs to the interdisciplinary field of civil engineering materials and microbiology, and relates to a hydrogel-encapsulated bacterial spore self-repairing material with pH responsiveness and a cement-based concrete self-repairing method. The self-repairing material comprises: a pH responsive hydrogel and bacterial spores encapsulated thereby, and a calcium source; wherein the hydrogel is prepared from a cross-linked hydrophilic polymer, and the bacterial spores comprise Bacillus alcalophilus (Bacillus pseudofiirmus) spores. The hydrogel used in the invention has pH responsiveness, encapsulates bacterial spores on the premise of ensuring that the cement strength is not damaged, and successfully realizes the self-healing of cement.
Description
Technical Field
The invention belongs to the field of interdisciplines of civil engineering materials and microbiology, and particularly relates to a hydrogel-encapsulated bacterial spore self-repairing material with pH responsiveness and a cement-based concrete self-repairing method using the self-repairing material.
Background
Cement is the most commonly used material in modern construction. After the tap water is injected, the cement paste can solidify aggregates such as stones and sands together to form cement-based materials such as mortar and concrete with good pressure resistance. However, the production of cement often causes serious environmental pollution and energy loss, including the emission of carbon dioxide and air particles, and the consumption of heat energy. In a natural environment, a cement-based material such as concrete is often cracked due to factors such as temperature change, so that external aqueous solution permeates, the permeation of the aqueous solution further causes damage to the structure of the cement-based material, the building structure is unstable in the past, the service life of the building is shortened, and the loss of cement is aggravated, so that the service life of the cement-based material is prolonged.
The prior art adopts microorganisms to carry out self-healing of cement. The use of microorganisms for self-healing of cement faces two major difficulties: firstly, great stress can be generated in the cement solidification process, the damage effect on bacterial spores can be caused, and the final self-healing result of cement is influenced; secondly, in order to ensure the recovery of bacterial spores, water-absorbing substances and nutrient substances are required to be added to ensure the normal life activities of bacteria, but the additional additives often have influence on the strength of the cement. In consideration of the factors, it is extremely urgent to research a novel hydrogel material with pH response characteristic to encapsulate bacterial spores, so that the self-healing of cement is realized, and the strength of the cement is not influenced.
Disclosure of Invention
Aiming at the defects of the prior art, the factors such as the survival rate of bacteria, the strength of cement, the property of an encapsulating material and the like are comprehensively considered, the invention provides the hydrogel encapsulating bacterial spore self-repairing material with pH responsiveness.
In order to achieve the above object, a first aspect of the present invention provides a hydrogel encapsulated bacterial spore self-repairing material having pH responsiveness, the self-repairing material comprising: a pH responsive hydrogel and bacterial spores encapsulated thereby, and a calcium source; wherein the hydrogel is prepared from a cross-linked hydrophilic polymer, and the bacterial spores comprise Bacillus alcalophilus (Bacillus pseudofiirmus) spores.
Bacillus alcalophilus (Bacillus pseudofiirmus) can survive in alkaline environment, can form spores in extremely severe environment, and has strong stress resistance. When the external conditions are appropriate, the bacterial spores are revived and metabolic activity is carried out, finally resulting in calcium carbonate (CaCO)3) The deposit of (2) can repair the crack of the cement-based material.
Encapsulation of Bacillus alcalophilus with a pH responsive hydrogel avoids crushing of bacterial spores during cement hydration. After the cement cracks, the hydrogel which is highly swelled under the condition of low pH absorbs the external water solution and rapidly swells, so that a good condition can be created for the recovery of bacterial spores. The hydrogel can be used as a nutrient substance to supply bacteria for metabolism, and in the research of Wang and the like, glutaraldehyde is used for inducing a crosslinking reaction, so that the bacterial activity is reduced, and the self-healing effect of cement is weakened.
The water swelling property of the hydrogel often affects the strength of the cement, and in the study of Jose Milla et al, the encapsulation of bacteria causes the strength of the cement to be reduced, which is difficult to be practically applied. According to the invention, single or composite hydrophilic polymers are used for interacting with calcium ions to prepare the hydrogel material with pH response characteristics of low swelling under a strong alkali condition and high swelling under a neutral acid bias condition, so that the influence of the expansion of the hydrogel in the cement hydration process on the strength of the cement-based material is reduced.
According to the present invention, in order to achieve sufficient swelling by water absorption to cause resuscitation of bacterial spores encapsulated therein, the content of the bacterial spores encapsulated in the hydrogel is 1.0X 107～9.8×107Spores per gram of hydrogel. In order to realize better repair, the mass ratio of the hydrogel to the calcium source is 1-1.5: 1.
according to the invention, due to the adoption of the crosslinking hydrophilic polymer, the hydrogel serving as the encapsulating material has large swelling ratio under the condition of low pH, and the water absorption swelling of the hydrogel can cause the bacterial spores encapsulated in the hydrogel to be recovered and carry out metabolic activity, so that calcite crystals are generated. The crosslinking hydrophilic polymer is prepared by crosslinking hydrophilic polymer, and can be prepared by various crosslinking methods in the field, such as crosslinking reaction with carbodiimide as a crosslinking agent. The hydrophilic polymer can be at least one selected from alginate, chitosan, polyvinylpyrrolidone, polyaspartate and dextran; preferably at least two selected from the group consisting of alginate, chitosan, polyvinylpyrrolidone, polyaspartate and dextran; further preferred is a combination of one selected from chitosan and dextran and one of alginate, polyvinylpyrrolidone and polyaspartate.
According to the invention, the calcium source has the effect of forming a calcium carbonate precipitate, in particular, the calcium source may be selected from at least one of calcium chloride, calcium nitrate, calcium acetate and calcium lactate; preferably at least two selected from the group consisting of calcium chloride, calcium nitrate, calcium acetate and calcium lactate.
According to a preferred embodiment of the present invention, the self-healing material further comprises an aluminum source, so that a Ca — Al deposit can be formed; the aluminum source may be selected from at least one of aluminum chloride, aluminum sulfate, aluminum nitrate, and aluminum sulfide.
According to the invention, the amount of the aluminum source can be determined according to the expected composition of Ca-Al sediment, and the molar ratio of the aluminum source to the calcium source is preferably 1-8: 2-7, most preferably 1: 6.
the alkalophilic bacillus spore adopted in the invention is preferably obtained by two stages of culture, wherein the culture medium A is adopted in the first stage of culture, and the culture medium B is adopted in the second stage of culture; the composition of medium a includes: peptone 4-6g/L, beef extract 2-4g/L, sodium bicarbonate 0.4-0.5g/L, sodium carbonate 0.5-0.6 g/L; the composition of medium B included: 0.1-0.3g/L of ammonium chloride, 0.01-0.03g/L of monopotassium phosphate, 0.2-0.3g/L of calcium chloride, 0.1-0.3g/L of potassium chloride, 0.1-0.3g/L of magnesium chloride hexahydrate, 0.005-0.02g/L of manganese sulfate monohydrate, 0.05-0.2g/L of yeast extract, 5-5.5 g/L of sodium citrate, 4-5g/L of sodium bicarbonate, 5-6g/L of sodium carbonate and 0.5-1.5mL of trace element solution SL 12B.
According to a preferred embodiment of the present invention, the hydrophilic polymer is alginate and chitosan, and the hydrogel is prepared by a method in which the concentration of the alginate is 1.0 to 4.0% (w/v), the concentration of the chitosan is 0.5 to 3.0% (w/v), the concentration of the calcium source is 0.09 to 0.27M in terms of calcium ions, and the concentration of the aluminum source is 0 to 0.15M in terms of aluminum ions. The addition of the chitosan greatly improves the flexural strength and compressive strength of the cement, the self-healing result of the cement is hardly influenced by the chitosan, and the hydrogel after the chitosan is added in a hydrogel swelling experiment obviously has the characteristics of high swelling under a low pH condition and low swelling under a high pH condition. The hydrogel obtained under the conditions has optimal pH response performance, can enhance the strength of the cement-based material to the maximum extent, and can simultaneously meet the requirements of strength enhancement and cement self-repair of the cement-based material.
The second aspect of the invention provides a preparation method of the hydrogel encapsulated bacterial spore self-repairing material with pH responsiveness, which comprises the following steps: and (3) mixing bacterial spores with the hydrophilic polymer solution, mixing with a calcium source and an optional aluminum source, and reacting to obtain the condensed hydrogel.
Preferably, the preparation method is selected from one of the following modes:
(1) mixing bacillus alcalophilus spores with an alginate solution, uniformly stirring, adding the alginate and spore mixed solution into a calcium source, an optional aluminum source and chitosan mixed solution under continuous stirring, draining condensed hydrogel beads and air-drying; the calcium source is preferably calcium chloride and calcium nitrate, and is further preferably calcium chloride and calcium nitrate in a molar ratio of 2-4: 1; the aluminum source is preferably aluminum chloride and aluminum sulfate, and is further preferably aluminum chloride and aluminum sulfate in a molar ratio of 4-6: 1; the molar ratio of the calcium source to the aluminum source on an atomic basis is preferably 5-7: 1;
(2) mixing basophilic bacillus spores with an alginate solution, uniformly stirring, adding the alginate and spore mixed solution into a calcium source, an optional aluminum source and a polyvinylpyrrolidone mixed solution in a flowing mode under continuous stirring, draining condensed hydrogel beads, performing ultralow-temperature circulating freeze thawing to enable the hydrogel beads to interpenetrate and crosslink, and then air-drying the hydrogel beads; the calcium source is preferably calcium chloride and calcium nitrate, and is further preferably calcium chloride and calcium nitrate in a molar ratio of 2-4: 1; the aluminum source is preferably aluminum chloride and aluminum sulfate, and is further preferably aluminum chloride and aluminum sulfate in a molar ratio of 4-6: 1; the molar ratio of the calcium source to the aluminum source on an atomic basis is preferably 5-7: 1;
(3) mixing basophilic bacillus spores and a polyaspartic acid salt solution, uniformly stirring, adding the polyaspartic acid salt and spore mixed solution into a calcium source, an aluminum source and chitosan mixed solution in a flowing mode under continuous stirring, carrying out ultrasonic treatment on the solution system under low-power ultrasonic waves, then placing the solution system under a low-temperature condition for reaction, finally placing the solution into an ethyl acetate solution, carrying out ultrasonic treatment, and drying; the calcium source is preferably calcium lactate and calcium acetate, and is further preferably calcium lactate and calcium acetate in a molar ratio of 2-4: 1; the aluminum source is preferably aluminum chloride; the molar ratio of the calcium source to the aluminum source on an atomic basis is preferably 5-7: 1;
(4) dissolving basophilic bacillus spores in a mixed solution of polyaspartate and chitosan, uniformly stirring, adding the mixed solution into cyclohexane containing Tween 80/Span 80 under low-power ultrasonic wave, adding a calcium source and an optional aluminum source solution into the system, continuing ultrasonic treatment after the addition is finished, placing the reaction system under a low-temperature condition for reaction, removing an oil phase of the reaction system, and drying; the calcium source is preferably calcium lactate and calcium acetate, and is further preferably calcium lactate and calcium acetate in a molar ratio of 2-4: 1; the aluminum source is preferably aluminum chloride; the molar ratio of the calcium source to the aluminum source on an atomic basis is preferably 5-7: 1;
(5) performing hydroformylation treatment on glucan, dissolving bacillus alcalophilus spores in a mixed solution of aldehyde glucose, calcium salt and an optional aluminum source, uniformly stirring, adding the mixed solution into cyclohexane containing Tween 80/Span 80 under continuous stirring, violently stirring to fully emulsify the mixed solution, finally adding an ethylenediamine solution under violent stirring, centrifugally collecting after reaction, washing with low-concentration ethanol, and airing; the calcium source is preferably calcium lactate and calcium acetate, and is further preferably calcium lactate and calcium acetate in a molar ratio of 2-4: 1; the aluminum source is preferably aluminum chloride; the molar ratio of the calcium source to the aluminum source on an atomic basis is preferably 5-7: 1;
(6) dissolving basophilic bacillus spores in a mixed solution of polyaspartate and alginate, uniformly stirring, adding the mixed solution of polyaspartate, alginate and spores into a calcium source and an optional aluminum source solution under continuous stirring, draining condensed hydrogel beads and air-drying; the calcium source is preferably calcium chloride and calcium nitrate, and is further preferably calcium chloride and calcium nitrate in a molar ratio of 2-4: 1; the aluminum source is preferably aluminum chloride and aluminum sulfate, and is further preferably aluminum chloride and aluminum sulfate in a molar ratio of 4-6: 1; the molar ratio of the calcium source to the aluminum source on an atomic basis is preferably 5 to 7: 1.
Further, in the mode (1), the concentration of the alginate solution is 1.0-4.0% (w/v), the concentration of the chitosan solution is 0.5-3.0% (w/v), the concentration of the calcium source is 0.09-0.27M, and the concentration of the aluminum source is 0-0.15M;
further, in the mode (2), the concentration of the alginate solution is 1.0-4.0% (w/v), the concentration of the calcium source is 0.09-0.27M, the concentration of the aluminum source is 0-0.15M, the concentration of the polyvinylpyrrolidone is 1.0-8.0% (w/v), and the ultralow temperature circulating freeze-thaw condition is that 3-10 circulating freeze-thaw cycles are performed at-80 ℃.
Further, in the mode (3), the concentration of the polyaspartic acid salt solution is 1.0 to 9.0% (w/v), the concentration of the calcium source is 0.09 to 0.27M, the concentration of the aluminum source is 0 to 0.15M, the concentration of the chitosan is 1.0 to 4.0% (w/v), the power of the ultrasound is 30 to 70Hz, and the time is 0.5 to 5min, and the reaction conditions include: the temperature is 4-8 ℃, the time is 20-28h, and the time of ultrasonic treatment in ethyl acetate solution is 30-60 s.
Further, in the mode (4), the concentration of the polyaspartic acid salt is 1.0-6.0% (w/v), the concentration of the chitosan is 0-4.0% (w/v), the power of the low-power ultrasonic wave is 30-70 Hz, the concentration of the calcium source is 0.27-0.81M, the concentration of the aluminum source is 0-0.15M, the continuous ultrasonic treatment time is 5-10 min, and the reaction conditions under the low-temperature condition include: the temperature is 4-8 ℃, and the time is 20-28 h.
Further, in the mode (5), a double bond is generated after the hydroformylation, and the double bond can perform a cross-linking reaction with ethylenediamine, the hydroformylation condition can be a conventional condition in the field, the concentration of the aldehyde glucose is 1.0-20.0%, the concentration of the calcium source is 0.18-0.36M, the concentration of the aluminum source is 0-0.15M, and the reaction time is 20-28 hours.
Further, in the mode (6), the concentration of the polyaspartic acid salt is 1.0-6.0% (w/v), the concentration of the alginate is 1.0-4.0% (w/v), the concentration of the calcium source is 0.09-0.27M, and the concentration of the aluminum source is 0-0.15M.
According to the process of the present invention, in modes (1) to (6), when the calcium salt is selected from organic calcium salts such as calcium acetate and/or calcium lactate, EDTA-Ca is preferably added to the reaction system2+To assist the cross-linking of calcium ions, EDTA-Ca2+The amount of (b) is such that the concentration of the compound in the mixed solution is 0.09-0.27M.
In a third aspect of the invention, a cement-based concrete self-repairing method is provided, wherein the hydrogel with pH responsiveness is doped into the cement-based concrete self-repairing method to encapsulate the mixed spore self-repairing material.
According to the invention, the mixing amount of the hydrogel is preferably 1.0wt% to 10.0wt% of the total mass of the cement-based concrete.
For better self-healing effect, the number of mixed spores of alkalophilic bacillus and bacillus kohlrabi contained in each cubic centimeter of cement-based concrete material is 2 multiplied by 105～3.5×105Preferably 2.54 × 105～3.07×105And (4) respectively.
According to a specific embodiment of the invention, the cement-based concrete self-repairing method comprises the following steps:
(1) two media (media A and B) were used for Bacillus alkalophilus culture, media A containing abundant nutrients for bacterial proliferation and media B being nutrient deficient for bacterial spore formation.
(2) A hydrophilic polymer selected from sodium alginate, chitosan, polyvinylpyrrolidone, polyaspartic acid and dextran, and a calcium source selected from calcium chloride, calcium nitrate, calcium acetate and calcium lactate are used for encapsulation of bacterial spores. Specifically, the following encapsulation methods can be employed: mixing bacillus alcalophilus spores with 1.0-4.0% (w/v) sodium alginate solution, and uniformly stirring. Adding the mixed solution of alginate and spore to the mixed solution of 0.09-0.27M calcium salt, 0-0.15M aluminum salt and 0.5-3.0% (w/v) chitosan under continuous stirring. The coagulated hydrogel beads were drained and air dried. ② mixing bacillus alcalophilus spores and 1.0-4.0% (w/v) sodium alginateThe solution is mixed and stirred evenly. Adding the mixed solution of sodium alginate and spores to 0.09-0.27M EDTA-Ca under continuous stirring2+0 to 0.15M aluminum salt and 1.0 to 8.0% (w/v) polyvinylpyrrolidone. The coagulated hydrogel beads were drained. And (3) performing cyclic freeze thawing for 3-10 times at the temperature of-80 ℃ to interpenetrate and crosslink the mixture, and then air-drying the mixture. Thirdly, mixing the alkalophilic bacillus spores with 1.0-9.0% (w/v) polyaspartic acid salt solution, and uniformly stirring. Under the condition of continuous stirring, adding the mixed solution of alginate and spores into 0.09-0.27M EDTA-Ca 2+0 to 0.15M aluminum salt and 1.0 to 4.0% (w/v) chitosan. The solution system is subjected to ultrasonic treatment for 0.5-5 min under low-power ultrasonic waves, and then is placed at 4-8 ℃ for reaction for 24 h. And finally, placing the solution in an ethyl acetate solution, performing ultrasonic treatment for 30-60 s, and drying. And fourthly, dissolving the alkalophilic bacillus spores into the mixed solution of polyaspartic acid salt (1.0-6.0% (w/v)) and chitosan (0-4.0% (w/v)), and uniformly stirring. The above mixed solution stream was added to Tween 80/Span 80 in cyclohexane under low power ultrasound. And then 0.27-0.81M of calcium salt and 0-0.15M of aluminum salt mixed solution are added into the system in a flowing mode, and the ultrasonic treatment is continued for 5-10 min after the adding in the flowing mode is finished. And (3) reacting the reaction system for 24 hours at the temperature of 4-8 ℃, removing the oil phase of the reaction system, and drying. And fifthly, performing hydroformylation treatment on the glucan. Dissolving bacillus alcalophilus spores in a mixed solution of 1.0-20.0% of aldehyde glucose, 0.18-0.36M of calcium salt and 0-0.15M of aluminum salt, and uniformly stirring. The aldehyde glucose and spore mixture solution was added to the Tween 80/Span 80 in cyclohexane with continuous stirring and stirred vigorously to emulsify it thoroughly. Finally, the ethylenediamine solution was added under vigorous stirring. After reacting for more than 24 hours, centrifugally collecting, washing with low-concentration ethanol, and airing. Sixthly, dissolving bacillus alcalophilus spores into a mixed solution of polyaspartate (1.0-6.0% (w/v)) and alginate (1.0-4.0% (w/v)), and uniformly stirring. Adding the mixed solution of polyaspartic acid salt alginate and spores into the mixed solution of 0.09-0.27M calcium salt and 0-0.15M aluminum salt under continuous stirring. The coagulated hydrogel beads were drained and air dried.
(3) Adding hydrogel encapsulating bacterial spores into cement according to the addition amount of 1.0-10%, and aging for 28 days.
(4) The strength of the prepared cement sample was evaluated using a cement bending and compression testing machine.
(5) The self-healing experiment is carried out by soaking the cement with cracks in tap water, and the crystal generation condition on the surface of the cement is characterized by using a Scanning Electron Microscope (SEM).
The invention provides a plurality of novel bacterial encapsulation methods for self-healing of cement, which ensure that bacteria play a good self-healing effect in cement-based materials, and the use of the encapsulation materials does not influence the cement strength. Applications include various basic mineral-based materials such as above ground and underwater concrete, reinforced concrete, building mortar, and putty coatings.
Compared with the prior art, the invention has the advantages that:
(1) the self-repairing material has good biocompatibility and no toxic or harmful effect on bacteria.
(2) The hydrogel used in the present invention has pH-responsive properties, which do not have a detrimental effect on the strength of the cement, and conversely, the addition of the hydrogel also provides an increase in the strength of the cement.
(3) The self-repairing material disclosed by the invention encapsulates bacterial spores on the premise of ensuring that the strength of cement is not damaged, so that the self-healing of the cement is successfully realized.
(4) The raw materials used by the self-repairing material are cheap and easy to obtain, and the self-repairing material is beneficial to promoting the further marketization of the microbial cement.
Additional features and advantages of the invention will be set forth in the detailed description which follows.
Drawings
The above and other objects, features and advantages of the present invention will become more apparent by describing in more detail exemplary embodiments thereof with reference to the attached drawings.
FIG. 1 shows dehydrated hydrogel spheres having mixed bacterial spores encapsulated therein, according to one embodiment of the invention.
Figure 2 shows the swelling of calcium alginate-chitosan hydrogel under different pH conditions. In the histogram of chitosan content in each group, from left to right, pH6, pH9, and pH12 were shown.
Figures 3A-3E show cement fracture healing after cement self-healing using chitosan + calcium alginate hydrogel encapsulated bacterial spores.
Fig. 4A to 4C show the formation of crystals on the surface of cement under a Scanning Electron Microscope (SEM) after self-repairing of cement using bacterial spores encapsulated by chitosan + calcium alginate hydrogel, which are the observation results corresponding to fig. 3A, 3B, and 3C, respectively.
Figures 5A-5B show cement fracture healing after cement self-healing using polyvinylpyrrolidone + calcium alginate hydrogel encapsulated bacterial spores. Fig. 5A and 5B show the results of adding 2.0% and 4.0% of polyvinylpyrrolidone, respectively.
FIGS. 6A-6C show the formation of crystals on the surface of cement under a Scanning Electron Microscope (SEM) after self-repair of cement using polyvinylpyrrolidone + calcium alginate hydrogel encapsulated bacterial spores. Fig. 6A and 6B correspond to the observation results in fig. 5A and 5B, respectively, and fig. 6C is an observation result when the polyvinylpyrrolidone addition amount is 4.5%.
FIGS. 7A-7C show cement fracture healing after cement self-healing using chitosan + calcium polyaspartate hydrogel encapsulated bacterial spores. Fig. 7A, 7B, and 7C show the results of the amounts of chitosan added, 1.0%, 0.5%, and not added, respectively.
FIGS. 8A-8C show the formation of crystals on the surface of cement under a Scanning Electron Microscope (SEM) after self-repair of cement using bacterial spores encapsulated with chitosan + calcium polyaspartate hydrogel. Fig. 8A, 8B, and 8C correspond to the observation results of fig. 7A, 7B, and 7C, respectively.
FIGS. 9A-9C show the formation of crystals on the surface of cement under a Scanning Electron Microscope (SEM) after self-repair of the cement using bacterial spores encapsulated with chitosan + calcium polyaspartate hydrogel. FIG. 9A, FIG. 9B and FIG. 9C show the results of adding 2.0%, 4.0% and 6.0% polyaspartic acid, respectively.
Fig. 10A-10C show the formation of crystals on the surface of cement under a Scanning Electron Microscope (SEM) after self-healing of the cement using dextran + calcium lactate hydrogel encapsulated bacterial spores. Fig. 10A, 10B, and 10C show the results of the amounts of glucan added of 4.0%, 8.0%, and 12.0%, respectively.
FIGS. 11A-11C show the formation of crystals on the surface of cement under a Scanning Electron Microscope (SEM) after self-repair of cement using bacterial spores encapsulated with calcium alginate + polyaspartic acid hydrogel. FIG. 11A, FIG. 11B and FIG. 11C show the results of adding polyaspartic acid in amounts of 1.0%, 2.0% and 4.0%, respectively.
Detailed Description
Preferred embodiments of the present invention will be described in more detail below. While the following describes preferred embodiments of the present invention, it should be understood that the present invention may be embodied in various forms and should not be limited by the embodiments set forth herein.
The hydrogel swelling characteristics are tested under different pH conditions, the pH responsive hydrogel which is high-swelling under the condition of low pH and low-swelling under the condition of high pH is obtained and then is used for encapsulating bacterial spores, a certain amount of hydrogel containing microbial spores is doped in the preparation process of the cement-based material, and the strength test and the self-healing test are carried out after the formed cement-based material sample block is obtained.
The present invention will be described in more detail with reference to examples. The examples, in which the specific conditions are not specified, were conducted under the conventional conditions or conditions recommended by the manufacturer. The reagents or instruments used are not indicated by the manufacturer, and are all conventional products available commercially.
In the following examples, Bacillus alkalophilus spores were produced by two stages of culture, medium A being used for the first stage of culture and medium B being used for the second stage of culture. The composition of medium a includes: 5g/L of peptone, 3g/L of beef extract, 0.42g/L of sodium bicarbonate and 0.53g/L of sodium carbonate (pH 9.7); the composition of medium B included: 0.2g/L of ammonium chloride, 0.02g/L of potassium dihydrogen phosphate, 0.225g/L of calcium chloride, 0.2g/L of potassium chloride, 0.2g/L of magnesium chloride hexahydrate, 0.01g/L of manganese sulfate monohydrate, 0.1g/L of yeast extract, 5.16g/L of sodium citrate, 4.2g/L of sodium bicarbonate, 5.3g/L of sodium carbonate, and 1mL of a trace element solution SL12B (pH 10).
The cement compressive strength and the cement flexural strength are tested by adopting a cement flexural and compressive tester.
The cement flexural strength is the ratio of the flexural strength of cement to the corresponding compressive strength, and is one of the indicators for the cement elasticity evaluation.
Example 1
1. Material
The bacterial encapsulating materials used in this example were alginate, chitosan, a calcium source, and an aluminum source. The calcium source is prepared from calcium chloride and calcium nitrate according to a molar ratio of 3: 1. The aluminum source is prepared from aluminum chloride and aluminum sulfate according to a molar ratio of 5: 1. The molar ratio of the calcium source (calcium ions) to the aluminum source (aluminum ions) is 6: 1. the chitosan calcium alginate hydrogel is used for encapsulating bacterial spores and self-repairing cement, and under the condition that external aqueous solution seeps into cracks of the cement, the hydrogel absorbs water to swell and stimulates the spores to recover so as to realize self-repairing. The mixing amount of the hydrogel is 3-5 g/100g of cement, and the number of spores contained in each gram of dry hydrogel is 1.0 multiplied by 107～9.8×107And (4) respectively.
2. Preparation of
50mL of alkalophilic bacillus spore (3-7% (w/v), wet weight) is mixed with 350mL of 2.0% (w/v) sodium alginate solution, and the mixture is stirred uniformly. And (3) adding the mixed solution of sodium alginate and spores into the mixed solution of 0.18M calcium salt, 0.03M aluminum salt and 0-3.0% (w/v) chitosan under continuous stirring. The coagulated hydrogel beads were drained and air dried as shown in fig. 1 (fig. 1 is chitosan concentration 1.0%).
3. Testing
The hydrogel swelling performance was evaluated in 0.1M Tris-HCl buffer at pH 6-12, and the results are shown in FIG. 2. When the content of chitosan is 1.0-1.5% (w/v), the swelling ratio of the hydrogel beads decreases with increasing pH. Therefore, it shows a lower swelling property in an alkaline environment.
4. Cement-based concrete self-repair
200g of cement (PO325 cement and PO425 cement), 300g of sand, 100g of tap water and a certain amount of hydrogel (the mixing amount is 1.0-10.0% of the total weight of the cement) are respectively weighed and prepared into concrete mortar samples. And pouring the mixed mortar into a mould to be solidified. And (3) wrapping the concrete mortar sample solidified for 24 hours by using a preservative film, aging for 28 days at 25 ℃, and testing the strength of the cement. When the mixing amount of sodium alginate is 2.0% (w/w), the chitosan content is 1.0-1.5% (w/v), and the calcium salt is prepared from calcium chloride and calcium nitrate according to a molar ratio of 3: 1, the aluminium salt consisting of aluminium chloride and aluminium sulphate in a molar ratio equal to 5: 1, the molar ratio of a calcium source (calcium ions) to an aluminum source (aluminum ions) is 6:1, the compressive strength of the cement is increased by 10.5-11.0%, the flexural strength is increased by 13.5-14.0%, and the flexural ratio is 17.0-17.5%.
And (3) soaking the cement sample block with the crack into tap water at 25 ℃ for self-healing test for 5-7 days, and observing the generation condition of the crystal on the surface of the cement by using a Scanning Electron Microscope (SEM). The self-healing results of the cement are shown in fig. 3A-3E. In fig. 3A-3C, the adopted cement is PO325 cement, hydrogel with 0-1.0% of chitosan addition amount is used for bacterial encapsulation, wherein fig. 3A represents that no chitosan is contained, fig. 3B represents that 0.5% of chitosan is contained, fig. 3C represents that 1.0% of chitosan is contained, and white calcite crystals appear on the surface of the cement after 5-7 days of cement self-healing experiments. In fig. 3D and 3E, the cement used was PO425 cement, and the cement healing was optimized to occur with a healing gap of about 4cm in length, about 1mm in width (fig. 3D) and about 3cm in length and about 0.8mm in width (fig. 3E). The hydrogels used were chitosan-free (FIG. 3D) and 1.0% (w/v) chitosan (FIG. 3E), respectively. The growth of the crystal on the surface of the cement under a Scanning Electron Microscope (SEM) is shown in fig. 4A to 4C, which are the observation results corresponding to fig. 3A, 3B, and 3C, respectively.
Example 2
1. Material
The bacterial encapsulating material used in this example was alginate, polyvinylpyrrolidone and a calcium source. The calcium source is prepared from calcium chloride and calcium nitrate according to a molar ratio of 3: 1. The aluminum source is prepared from aluminum chloride and aluminum sulfate according to a molar ratio of 5: 1. The molar ratio of the calcium source (calcium ions) to the aluminum source (aluminum ions) is 6: 1. the polyvinylpyrrolidone calcium alginate hydrogel is used for encapsulating bacterial spores and is used for self-repairing cement when external aqueous solution permeatesUnder the condition of cement cracks, the hydrogel absorbs water and expands to stimulate spores to recover, so that self-healing is realized. The mixing amount of the hydrogel is 3-5 g/100g of cement, and the number of spores contained in each gram of dry hydrogel is 1.0 multiplied by 107～9.8×107And (4) respectively.
2. Preparation of
50ml of basophilic bacillus spore (3-7% (w/v), wet weight) is mixed with 350ml of 2.0% (w/v) sodium alginate solution, and the mixture is stirred uniformly. Respectively adding the sodium alginate and spore mixed solution into 0.18M calcium source and 0.18M EDTA-Ca under continuous stirring2+0.03M aluminum source and 2.0%, 4.0% and 4.5% (w/v) polyvinylpyrrolidone. The coagulated hydrogel beads were drained. The cross-linking was interpenetrated by 8 cycles of freeze-thaw at-80 ℃ and then air-dried.
3. Cement-based concrete self-repair
200g of cement, 300g of sand, 100g of tap water and a certain amount of hydrogel (the mixing amount is 1.0-10.0% of the total weight of the cement) are respectively weighed and prepared into a concrete mortar sample. And pouring the mixed mortar into a mould to be solidified. And (3) wrapping the concrete mortar sample solidified for 24 hours by using a preservative film, aging for 28 days at 25 ℃, and testing the strength of the cement. When the content of sodium alginate is 4.0% (w/w), the content of polyvinylpyrrolidone is 2.0%, 4.0% and 4.5% (w/v), and the calcium salt is prepared from calcium chloride and calcium nitrate according to the molar ratio of 3: 1, the aluminium salt consisting of aluminium chloride and aluminium sulphate in a molar ratio equal to 5: 1, the molar ratio of a calcium source (calcium ions) to an aluminum source (aluminum ions) is 6:1, the compressive strength of the cement is increased by 7.5-10.0%, the flexural strength is increased by 12.5-14.0%, and the flexural ratio is 18.0-19.5%.
And (3) soaking the cement sample block with the crack into tap water at 25 ℃ for self-healing test for 5-7 days, and observing the generation condition of the crystal on the surface of the cement by using a Scanning Electron Microscope (SEM). As a result, as shown in FIGS. 5A-5B and FIGS. 6A-6C, a trace amount of white crystals visible to the naked eye were present on the surface of the cement, but no complete healing gaps were observed, and a large amount of white crystals were still observed on the surface of the cement sample under SEM.
Example 3
1. Material
The bacterial encapsulating material used in this example was polyaspartate, chitosan, and a calcium source. The calcium source is prepared from calcium lactate and calcium acetate according to a molar ratio of 3: 1. The aluminum source is aluminum chloride. The molar ratio of the calcium source (calcium ions) to the aluminum source (aluminum ions) is 6: 1. the chitosan calcium polyaspartate hydrogel is used for encapsulating bacterial spores and is used for cement self-repair, and under the condition that external aqueous solution seeps into cracks of cement, the hydrogel absorbs water to swell and stimulates the spores to recover so as to realize self-repair. The mixing amount of the hydrogel is 3-5/100 g of cement, and the number of spores contained in each gram of dry hydrogel is 1.0 multiplied by 107～9.8×107And (4) respectively.
2. Preparation of
50ml of alkalophilic bacillus spore (3-7% (w/v), wet weight) and 350ml of 1.0-9.0% (w/v) polyaspartic acid salt solution are mixed and stirred uniformly. The alginate and spore mixture was added to a 0.18M calcium source, 0.18M EDTA-Ca with continuous stirring2+0.03M aluminum ion and 0, 0.5 percent and 1.0 percent (w/v) chitosan. The solution system is subjected to ultrasonic treatment for 0.5-5 min under low-power ultrasonic waves, and then is placed at 4-8 ℃ for reaction for 24 h. And finally, placing the solution in an ethyl acetate solution, performing ultrasonic treatment for 30-60 s, and drying.
3. Cement-based concrete self-repair
200g of cement, 300g of sand, 100g of tap water and a certain amount of hydrogel (the mixing amount is 1.0-10.0% of the total weight of the cement) are respectively weighed and prepared into a concrete mortar sample. And pouring the mixed mortar into a mould to be solidified. And (3) wrapping the concrete mortar sample solidified for 24 hours by using a preservative film, aging for 28 days at 25 ℃, and testing the strength of the cement. When the mixing amount is 2.0-6.0% (w/w), the content of polyaspartic acid salt is 1.0-3.0% (w/v), the content of chitosan is 2.0-4.0% (w/v), and the calcium salt is prepared from calcium lactate and calcium acetate according to the molar ratio of 3: 1, aluminum salt is aluminum chloride, and the molar ratio of a calcium source (calcium ions) to an aluminum source (aluminum ions) is 6: under the condition of 1, the compressive strength of the cement is increased by 6.3-9.7%, the flexural strength is increased by 10.6-12.9%, and the flexural ratio is 20.0-23.5%.
And (3) soaking the cement sample block with the crack into tap water at 25 ℃ for self-healing test for 5-7 days, and observing the generation condition of the crystal on the surface of the cement by using a Scanning Electron Microscope (SEM). As a result, as shown in FIGS. 7A to 7C and FIGS. 8A to 8C, the cement surface had no white crystals visible to the naked eye, and a very small amount of crystals were observed under SEM.
Example 4
1. Material
The bacterial encapsulating material used in this example was chitosan, polyacrylic acid, and a calcium source. The calcium source is prepared from calcium lactate and calcium acetate according to a molar ratio of 3: 1. The aluminum source is aluminum chloride. The molar ratio of the calcium source (calcium ions) to the aluminum source (aluminum ions) is 6: 1. the chitosan-calcium polyacrylate hydrogel is used for encapsulating bacterial spores and is used for cement self-repair, and under the condition that external aqueous solution seeps into cracks of cement, the hydrogel absorbs water to swell and stimulates the spores to recover so as to realize self-repair. The mixing amount of the hydrogel is 3-5 g/100g of cement, and the number of spores contained in each gram of dry hydrogel is 1.0 multiplied by 107～9.8×107And (4) respectively.
2. Preparation of
Dissolving 20-50 mL of alkalophilic bacillus spore (3-7% (w/v), wet weight) in 100-400 mL of a polyacrylic acid (1.0-6.0% (w/v)) and chitosan (0.5-4.0% (w/v)) mixed solution, and uniformly stirring. The above mixed solution stream was added to Tween 80/Span 80 in cyclohexane under low power ultrasound. And then adding a mixed solution of 0.36M calcium salt and 0.06M aluminum salt into the system in a flowing manner, and continuing ultrasonic treatment for 5-10 min after the adding in the flowing manner is finished. And (3) reacting the reaction system for 24 hours at the temperature of 4-8 ℃, removing the oil phase of the reaction system, and drying.
3. Cement-based concrete self-repair
200g of cement, 300g of sand, 100g of tap water and a certain amount of hydrogel (the mixing amount is 1.0-10.0% of the total weight of the cement) are respectively weighed and prepared into a concrete mortar sample. And pouring the mixed mortar into a mould to be solidified. And (3) wrapping the concrete mortar sample solidified for 24 hours by using a preservative film, aging for 28 days at 25 ℃, and testing the strength of the cement. In the mixing amount of 1.0-3.0% (w/w), the content of polyaspartic acid salt is 3.0-4.6% (w/v), the content of chitosan is 0.5-2.0% (w/v), and the calcium salt is prepared from calcium lactate and calcium acetate according to the molar ratio of 3: 1, aluminum salt is aluminum chloride, and the molar ratio of a calcium source (calcium ions) to an aluminum source (aluminum ions) is 6: under the condition of 1, the compressive strength of the cement is increased by 9.6-11.0%, the flexural strength is increased by 12.8-14.0%, and the flexural ratio is 17.0-17.5%.
The cement sample block with cracks is soaked in tap water at 25 ℃ for self-healing test for 5-7 days, and the generation condition of crystals on the surface of the cement is observed by using a Scanning Electron Microscope (SEM), and the results are shown in FIGS. 9A-9C, and no calcium carbonate crystals are observed under the SEM.
Example 5
1. Material
The bacterial encapsulating material used in this example was dextran and a calcium source. The calcium source is prepared from calcium lactate and calcium acetate according to a molar ratio of 3: 1. The aluminum source is aluminum chloride. The molar ratio of the calcium source (calcium ions) to the aluminum source (aluminum ions) is 6: 1. the glucan hydrogel is used for encapsulating bacterial spores and is used for cement self-repair, and under the condition that external aqueous solution seeps into a cement crack, the hydrogel absorbs water to swell and stimulates the spores to recover so as to realize self-repair. The mixing amount of the hydrogel is 3-5 g/100g of cement, and the number of spores contained in each gram of dry hydrogel is 1.0 multiplied by 107～9.8×107And (4) respectively.
2. Preparation of
And performing hydroformylation treatment on the glucan. Dissolving 20-50 mL of alkalophilic bacillus spore (3-7% (w/v), wet weight) in 100-400 mL of a mixed solution of 1.0-20.0% aldehyde glucose, 100-400 mL of 0.27M calcium salt and 0.045M aluminum salt, and uniformly stirring. The aldehyde glucose and spore mixture solution was added to the Tween 80/Span 80 in cyclohexane with continuous stirring and stirred vigorously to emulsify it thoroughly. Finally, the ethylenediamine solution was added under vigorous stirring. After reacting for more than 24 hours, centrifugally collecting, washing with low-concentration ethanol, and airing.
3. Cement-based concrete self-repair
200g of cement, 300g of sand, 100g of tap water and a certain amount of hydrogel (the mixing amount is 1.0-10.0% of the total weight of the cement) are respectively weighed and prepared into a concrete mortar sample. And pouring the mixed mortar into a mould to be solidified. And (3) wrapping the concrete mortar sample solidified for 24 hours by using a preservative film, aging for 28 days at 25 ℃, and testing the strength of the cement. The mixing amount is 1.0-3.0% (w/w), the aldehyde glucose content is 10.0-15.0% (w/v), and the calcium salt is prepared from calcium lactate and calcium acetate according to a molar ratio of 3: 1, aluminum salt is aluminum chloride, and the molar ratio of a calcium source (calcium ions) to an aluminum source (aluminum ions) is 6: under the condition of 1, the compressive strength of the cement is increased by 7.8-13.7%, the flexural strength is increased by 6.8-8.5%, and the flexural ratio is 9.8-11.6%.
The cement sample block with cracks is soaked in tap water at 25 ℃ for self-healing test for 5-7 days, and the generation condition of crystals on the surface of the cement is observed by using a Scanning Electron Microscope (SEM), and the results are shown in FIGS. 10A-10C, and no calcium carbonate crystals are observed under the SEM.
Example 6
1. Material
The bacterial encapsulating materials used in this example were alginate, polyaspartate, and a calcium source. The calcium source is prepared from calcium chloride and calcium nitrate according to a molar ratio of 3: 1. The aluminum source is prepared from aluminum chloride and aluminum sulfate according to a molar ratio of 5: 1. The molar ratio of the calcium source (calcium ions) to the aluminum source (aluminum ions) is 6: 1. the polyaspartate calcium alginate hydrogel is used for encapsulating bacterial spores and self-repairing cement, and under the condition that external aqueous solution seeps into cracks of the cement, the hydrogel absorbs water to swell and stimulates the spores to recover so as to realize self-repairing. The mixing amount of the hydrogel is 3-5 g/100g of cement, and the number of spores contained in each gram of dry hydrogel is 1.0 multiplied by 107～9.8×107And (4) respectively.
2. Preparation of
50mL of Bacillus alcalophilus spores (3-7% (w/v), wet weight) were dissolved in 350mL of a mixed solution of polyaspartate (1.0%, 2.0%, and 4.0% (w/v)) and alginate (2.0% (w/v)), and stirred uniformly. The polyaspartate alginate and spore mixed solution was added to the 0.18M calcium salt and 0.03M aluminum salt mixed solution with continuous stirring. The coagulated hydrogel beads were drained and air dried.
3. Cement-based concrete self-repair
200g of cement, 300g of sand, 100g of tap water and a certain amount of hydrogel (the mixing amount is 1.0-10.0% of the total weight of the cement) are respectively weighed and prepared into a concrete mortar sample. And pouring the mixed mortar into a mould to be solidified. And (3) wrapping the concrete mortar sample solidified for 24 hours by using a preservative film, aging for 28 days at 25 ℃, and testing the strength of the cement. The content of alginate is 1.0-3.0% (w/w), the content of polyaspartic acid salt is 1.5-2.5% (w/v), the content of polyaspartic acid salt is 3.0-4.5% (w/v), and the aluminum salt is prepared by mixing aluminum chloride and aluminum sulfate according to a molar ratio of 5: 1, the molar ratio of a calcium source (calcium ions) to an aluminum source (aluminum ions) is 6: under the condition of 1, the compressive strength of the cement is increased by 10.5-12.6%, the flexural strength is increased by 13.5-15.7%, and the flexural ratio is 16.5-17.8%.
The cement sample block with cracks is soaked in tap water at 25 ℃ for self-healing test for 5-7 days, and the generation condition of crystals on the surface of the cement is observed by using a Scanning Electron Microscope (SEM), and the results are shown in FIGS. 11A-11C, and a small amount of white calcium carbonate crystals are observed under the SEM.
Having described embodiments of the present invention, the foregoing description is intended to be exemplary, not exhaustive, and not limited to the embodiments disclosed. Many modifications and variations will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments.
Claims (13)
1. A hydrogel-encapsulated bacterial spore self-healing material with pH responsiveness, comprising: a pH responsive hydrogel and bacterial spores, an aluminum source and a calcium source encapsulated thereby; wherein the hydrogel is prepared from crosslinking hydrophilic macromolecules, and the bacterial spore comprises Bacillus alcalophilus (Bacillus alcalophilus)) (Bacillus pseudofirmus) Spore formation; the crosslinking hydrophilic polymer is prepared by crosslinking reaction of hydrophilic polymer, wherein the hydrophilic polymer is alginate and chitosan, and the concentration of the alginate in the method for preparing the hydrogel1.0-4.0% (w/v), the concentration of the chitosan is 0.5-3.0% (w/v), and the molar ratio of the aluminum source to the calcium source is 1-8: 2 to 7.
2. The pH-responsive hydrogel-encapsulated bacterial spore self-healing material of claim 1, wherein the hydrogel has an encapsulated bacterial spore content of 1.0 x 107~9.8×107Spores per gram of hydrogel; the mass ratio of the hydrogel to the calcium source is 1-1.5: 1.
3. the pH-responsive hydrogel encapsulated bacterial spore self-healing material of claim 1, wherein the calcium source is selected from at least one of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate.
4. The pH-responsive hydrogel encapsulated bacterial spore self-healing material of claim 3, wherein the calcium source is selected from at least two of calcium chloride, calcium nitrate, calcium acetate, and calcium lactate.
5. The pH-responsive hydrogel encapsulated bacterial spore self-healing material of claim 1, wherein the aluminum source is selected from at least one of aluminum chloride, aluminum sulfate, aluminum nitrate, and aluminum sulfide.
6. The pH-responsive hydrogel encapsulated bacterial spore self-healing material of any one of claims 1 to 5, wherein the concentration of the calcium source is 0.09-0.27M in terms of calcium ions.
7. The preparation method of the pH-responsive hydrogel encapsulated bacterial spore self-repairing material as claimed in any one of claims 1 to 6, comprising the following steps: and (3) mixing bacterial spores with the hydrophilic polymer solution, mixing with a calcium source and an aluminum source, and reacting to obtain the condensed hydrogel.
8. The production method according to claim 7, wherein the production method comprises:
mixing bacillus alcalophilus spores and an alginate solution, stirring uniformly, adding the alginate and spore mixed solution into a calcium source, an aluminum source and chitosan mixed solution in a flowing mode under continuous stirring, draining condensed hydrogel beads and air-drying.
9. The production method according to claim 8, wherein the calcium source is calcium chloride and calcium nitrate; the aluminum source is aluminum chloride and aluminum sulfate; the molar ratio of the calcium source to the aluminum source is 5-7:1 in terms of atoms.
10. The preparation method according to claim 9, wherein the calcium source is calcium chloride and calcium nitrate in a molar ratio of 2-4:1, and the aluminum source is aluminum chloride and aluminum sulfate in a molar ratio of 4-6: 1.
11. The method according to claim 8, wherein the alginate solution has a concentration of 1.0 to 4.0% (w/v), the chitosan solution has a concentration of 0.5 to 3.0% (w/v), the calcium source has a concentration of 0.09 to 0.27M, and the aluminum source has a concentration of 0.03 to 0.15M;
when the calcium salt is selected from calcium acetate and/or calcium lactate, EDTA-Ca is added to the reaction system2+。
12. A cement-based concrete self-repairing method, which is characterized in that the hydrogel with pH responsiveness of any one of claims 1 to 6 is doped with the mixed spore self-repairing material during the hydration process of a cement-based concrete material; the mixing amount of the hydrogel is 1.0-10.0 wt% of the total mass of the cement-based concrete;
the number of mixed spores of the alkalophilic bacillus and the bacillus kojii contained in each cubic centimeter of the cement-based concrete material is 2 multiplied by 105~3.5×105And (4) respectively.
13. The method of self-healing cementitious concrete of claim 12, wherein each cubic centimeter of cementitious concreteThe number of mixed spores of Bacillus alcalophilus and Bacillus ke contained in the soil material was 2.54 × 105~3.07×105And (4) respectively.
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