Concrete reinforcement particles and their applications

Abstract

The present invention relates to the field of microbial technology, and in particular to a concrete reinforcing particle containing microorganisms and its application. The concrete reinforcing particle is a modified zeolite particle immobilized with microorganisms; the microorganism includes Bacillus pasteurianus; the modified zeolite particle is obtained by impregnating and modifying natural zeolite particles with an acidic solution or an alkaline solution. The present invention uses modified zeolite particles obtained by impregnating and modifying natural zeolite particles with an acidic solution or an alkaline solution as a basic carrier, and immobilizes Bacillus pasteurianus to obtain the concrete reinforcing particle. The concrete reinforcing particle can replace the fine aggregate component in concrete in equal amounts, and significantly improves the repair effect of concrete cracks. In particular, it has outstanding performance in performance tests such as the compressive strength of the repaired concrete, the compressive strength recovery rate within a stage time, and the 24h water absorption rate of the repaired concrete.

Description

Technical Field

[0001] The present invention relates to the field of microbial technology, and in particular to concrete reinforcing particles containing microorganisms and applications thereof. Background Art

[0002] Concrete cracks are physical structural changes caused by internal and external factors. The occurrence of concrete cracks will significantly reduce the bearing capacity, durability and waterproofness of concrete structures. Microbial self-repair of concrete cracks is a popular and eco-friendly new technology. It uses a certain method to incorporate microorganisms into fresh concrete. The mineralization of microorganisms transforms the substrate into a substance with a certain bonding strength, thereby filling the cracks and achieving the purpose of self-repair of cement-based material cracks.

[0003] At present, microbial self-repair technology often uses porous carriers to immobilize microorganisms and then incorporates them into fresh concrete. The attached carriers include silica gel, nano-graphite sheets, expanded clay, and zeolite. However, from the aspects of pressure resistance, economy, bacterial immobilization capacity, and compatibility between the carrier and the concrete matrix, the above-mentioned carriers all have their own inherent shortcomings, and the effect of repairing concrete cracks is not good.

[0004] In view of this, the present invention is proposed. Summary of the Invention

[0005] The present invention provides concrete-reinforcing particles and their application. These particles are made from modified zeolite particles, obtained by impregnating natural zeolite particles with an acidic or alkaline solution, and immobilized with Bacillus pasteurianus. These particles can replace an equal amount of fine aggregate in concrete, significantly improving the repair effect of concrete cracks.

[0006] Specifically, the technical solution of the present invention is as follows:

[0007] In a first aspect, the present invention provides concrete reinforcing particles, which are modified zeolite particles immobilized with microorganisms; the microorganisms include Bacillus pasteurianus; and the modified zeolite particles are obtained by modifying natural zeolite particles by impregnation in an acidic solution or an alkaline solution.

[0008] The present invention utilizes modified zeolite particles to immobilize Bacillus pasteurianus. The modified zeolite particles are obtained by impregnating and modifying natural zeolite particles with an acidic solution or an alkaline solution. Among them, the main principle of using an acidic solution to modify natural zeolite is to increase the porosity and improve the specific surface area of ​​the zeolite particles by removing impurities in the pores of the natural zeolite; the main principle of using an alkaline solution to modify natural zeolite is to change the silicon-aluminum ratio so that the zeolite forms more regular mesopores. Compared with unmodified natural zeolite particles, the diffusion force of the modified zeolite particles impregnated with an acidic solution or an alkaline solution is enhanced in the present invention. The present invention utilizes modified zeolite particles to immobilize Bacillus pasteurianus, and the adsorption capacity of Bacillus pasteurianus is significantly improved compared with unmodified natural zeolite particles.

[0009] In a preferred embodiment of the present invention, the modified zeolite particles are obtained by impregnating natural zeolite particles with an acidic solution. Although alkaline solution modification can also improve the diffusion and adsorption capacity of zeolite, the porosity of zeolite modified with an acidic solution is significantly higher than that of zeolite modified with an alkaline solution. Zeolite modified with an acidic solution exhibits a significantly greater adsorption capacity for Bacillus pasteurianus than zeolite modified with an alkaline solution.

[0010] In the present invention, the H + The concentration is preferably 0.2-0.6 mol / L, more preferably 0.3-0.5 mol / L. The impregnation modification time is preferably 4-8 hours, more preferably 5-7 hours. In a more preferred embodiment of the present invention, the acidic solution is an HCl solution. The concentration of the HCl solution is preferably 0.3-0.5 mol / L, more preferably 0.4 mol / L. When the zeolite is modified using the HCl solution, the impregnation modification time is preferably 5-7 hours, more preferably 6 hours. The preferred embodiment of the present invention can achieve a relatively better zeolite modification effect.

[0011] In the present invention, the microorganism is preferably subjected to stress treatment.

[0012] In the present invention, the stress treatment method preferably includes one or more of the following:

[0013] (1) placing the microorganisms in a water-deficient environment for 2-5 days;

[0014] (2) Soak the microorganisms in a 0.05-0.2 mol / L MnCl2 solution for 1-5 hours;

[0015] (3) The microorganisms are placed under stress conditions at 70-85°C for 10-20 minutes.

[0016] In method (1), the duration of the stress treatment is preferably 2-4 days, more preferably 3 days.

[0017] In method (2), the concentration of the MnCl2 solution is preferably 0.8-0.15 mol / L, more preferably 0.1 mol / L; the soaking time is preferably 2-4 h, more preferably 3 h.

[0018] In mode (3), the temperature condition is preferably 75-85°C, more preferably 80°C; the time of the stress treatment is preferably 12-16 minutes, more preferably 15 minutes.

[0019] Microorganisms that have undergone stress treatment are better able to adapt to the concrete environment and show better repair effects in the subsequent longer-term mineralization repair process.

[0020] In a more preferred embodiment of the present invention, the stress treatment includes the above-mentioned methods (1), (2), and (3). The microorganisms treated by the above-mentioned methods (1), (2), and (3) have a higher spore conversion rate, and the concrete reinforcement particles obtained after being immobilized with the modified zeolite particles perform best in repairing concrete cracks.

[0021] In another alternative embodiment of the present invention, the microorganism can be directly immobilized on modified zeolite particles using commercially available spore-forming Bacillus pasteurianus without undergoing stress treatment. While the concrete-reinforced particles obtained in this manner are less effective at repairing concrete cracks than the previously described stress-treated Bacillus pasteurianus, they are superior to unstressed, standard Bacillus pasteurianus.

[0022] Furthermore, in the present invention, the method for immobilizing microorganisms on modified zeolite particles preferably comprises the following steps:

[0023] S1. Shake and mix the modified zeolite particles and the microbial suspension at a mass ratio of 1:(1.5-3) for 3-6 hours to obtain a mixed material;

[0024] S2. The mixed material described in step S1 is placed under vacuum solidification at 0.06-0.1 MPa for 15-30 minutes to obtain a solid material;

[0025] S3. Drying the zeolite in the solid-loaded material in step S2 at 40-60° C. for 30-120 min to obtain modified zeolite particles loaded with microorganisms.

[0026] The present invention first shakes and mixes the modified zeolite particles with the microbial suspension. In the present invention, the concentration of the microbial suspension is preferably 0.5×10 7 cfu / mL-5×10 7 cfu / mL, more preferably 1×10 7 cfu / mL-3×10 7cfu / mL. The mass ratio of the modified zeolite particles to the microbial suspension is 1:(1.5-3), preferably 1:(1.8-2.5), and more preferably 4:9. The shaking mixing time is 3-6 hours, preferably 4-5 hours.

[0027] After shaking and mixing, a mixed material is obtained. In the present invention, the mixed material is placed under vacuum conditions for solidification. In the present invention, the vacuum conditions are 0.06-0.1 MPa, preferably 0.08 MPa. The solidification time is 15-30 minutes, preferably 20 minutes.

[0028] After vacuum solidification, a solid-loaded material is obtained. In the present invention, the zeolite in the solid-loaded material is removed and dried. In the present invention, the drying temperature is 40-60°C, preferably 45-55°C, and more preferably 50°C. The drying time is 30-120 minutes, preferably 50-70 minutes, and more preferably 60 minutes. After the drying process, modified zeolite particles with microorganisms immobilized are obtained.

[0029] In a second aspect, the present invention provides concrete comprising the concrete reinforcing particles.

[0030] In the present invention, the mass proportion of the concrete reinforcing particles in the concrete is preferably 5%-32.5%, more preferably 10%-20%, and even more preferably 12%-14%. The concrete reinforcing particles can replace the fine aggregate component in concrete in equal amounts, significantly improving the repair effect of concrete cracks.

[0031] In a preferred embodiment of the present invention, the concrete-reinforcing particles and river sand together constitute the fine aggregate component of the concrete. The fine aggregate component preferably accounts for 25% to 40% by weight of the concrete, more preferably 30% to 35% by weight. The concrete-reinforcing particles preferably account for 30% to 50% of the fine aggregate component, more preferably 35% to 45%, and even more preferably 40%.

[0032] Furthermore, the concrete preferably also includes at least one of calcium chloride, urea, tryptone, and yeast extract, and more preferably includes calcium chloride, urea, tryptone, and yeast extract. Calcium chloride, urea, tryptone, and yeast extract can be absorbed and utilized by microorganisms in the concrete reinforcement particles, further enhancing the effectiveness of the microorganisms in the concrete crack repair process.

[0033] In a third aspect, the present invention provides the concrete reinforcing particles, or use of the concrete in crack repair.

[0034] In this invention, crack repair encompasses both conventional concrete crack filling and self-repair of the concrete after cracks develop. Compared to existing conventional microbial self-repair technologies, this invention utilizes modified zeolite particles as a carrier, immobilized with Bacillus pasteurianus, significantly improving both the repair capability of conventional concrete cracks and the self-repair capability of concrete after cracks develop. In particular, performance tests show outstanding performance in terms of compressive strength of the self-repaired concrete, compressive strength recovery rate over a specific period of time, and 24-hour water absorption of the repaired concrete.

[0035] Beneficial effects:

[0036] The present invention provides a concrete reinforcing particle, which is a modified zeolite particle immobilized with microorganisms; the microorganisms include Bacillus pasteurianus; the modified zeolite particles are obtained by impregnating and modifying natural zeolite particles with an acidic solution or an alkaline solution. The present invention uses modified zeolite particles obtained by impregnating and modifying natural zeolite particles with an acidic solution or an alkaline solution as a basic carrier, and immobilizes Bacillus pasteurianus to obtain the concrete reinforcing particles. The concrete reinforcing particles can replace the fine aggregate component in concrete in equal amounts, and the repair effect of concrete cracks is significantly improved. In particular, they have outstanding performance in performance tests such as the compressive strength of the repaired concrete, the compressive strength recovery rate within a stage time, and the 24-hour water absorption rate of the repaired concrete. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] In order to more clearly illustrate the technical solutions of the present invention or the prior art, the drawings required for use in the embodiments or the description of the prior art will be described below.

[0038] Figure 1 This is a morphology diagram of Bacillus pasteurianus after Gram staining in Example 1 of the present invention.

[0039] Figure 2 This is a morphology diagram of natural zeolite particles in Example 1 of the present invention.

[0040] Figure 3 This is a morphology diagram of zeolite particles after vacuum immobilization of microorganisms in Example 1 of the present invention.

[0041] Figure 4 This is a graph showing the relationship between the crack width and the repair rate of the concrete test blocks of groups I, II, and III in Experimental Example 2 of the present invention after 28 days of crack repair.

[0042] Figure 5 This is the BEC in Experimental Example 2 of the present invention. m Comparative photos of the 28d repair process of cracks in the two groups of concrete specimens, BEC and BEC.

[0043] Figure 6 This is the BEC in Experimental Example 2 of the present invention. mSEM image analysis results of the two groups of concrete specimens at different positions and different magnifications after the cracks of the BEC and BEC groups were repaired 28 days ago; the scale values ​​of (a), (b), (c) and (d) are 100μm, 100μm, 200μm and 50μm respectively.

[0044] Figure 7 This is the BEC in Experimental Example 2 of the present invention. m FTIR analysis results of white crystals after 28 days of repair of concrete specimen cracks. DETAILED DESCRIPTION

[0045] The following examples are provided to illustrate the present invention but are not intended to limit the scope of the present invention. Without departing from the spirit and substance of the present invention, modifications or substitutions made to the methods, steps or conditions of the present invention are within the scope of protection of the present invention.

[0046] Unless otherwise specified, the experimental materials, reagents, instruments, etc. used in the examples of the present invention are commercially available; unless otherwise specified, all technical means in the examples of the present invention are conventional means well known to those skilled in the art.

[0047] Example 1

[0048] This embodiment provides a concrete reinforcement particle, and the raw materials and preparation method thereof are as follows:

[0049] (1) Raw materials:

[0050] The mineralizing microorganism used in the experiment was Bacillus pasteurii (BNCC337394, freeze-dried powder, purchased from Beina Biotech - Henan Industrial Microbial Engineering Technology Research Center).

[0051] The culture medium used for microbial cultivation was LB liquid medium, which consisted of yeast extract (5 g / L), tryptone (10 g / L), sodium chloride (10 g / L), and deionized water. Urea (20 g / L) was also added to adjust the pH to 7.4.

[0052] Gram staining reagent for Bacillus pasteurianus.

[0053] The experimental concrete was made with strength grade C40 and P·O 42.5 cement was used. The coarse aggregate was crushed stone with a particle size of 5-20 mm and continuous grading. The fine aggregate was river sand with a fineness modulus of 2.9. The zeolite was commercially available natural zeolite filter material with a particle size of 1.0-2.0 mm and a density of 2.1 g / cm 3 The chemical composition of zeolite is shown in Table 1; the water reducing agent is polycarboxylic acid water reducing agent powder, and the water reducing rate is 30%.

[0054] Table 1 Chemical composition of zeolite

[0055] Element <![CDATA[SiO2]]> <![CDATA[Al2O3]]> CaO <![CDATA[K2O]]> <![CDATA[Na2O]]> content(%) 68.50 12.43 3.55 3.01 1.17

[0056] The morphology of Bacillus pasteurianus after Gram staining is shown in Figure 1 .

[0057] The morphology of natural zeolite particles can be found in Figure 2 .

[0058] (2) Cultivation of microorganisms and preparation of spore suspension:

[0059] Before culturing the microorganisms, sterilize the LB medium components at 121°C for 20 minutes. Then, filter-sterilize the urea and mix them together for later use. The first step in microbial cultivation is to activate the lyophilized powder. Add the activated bacterial suspension to fresh culture medium at a ratio of 5%. Incubate the culture in a shaker at 210 rpm and 37°C for 28 hours to increase the concentration of the culture. Store the cultured solution in a refrigerator at 4°C.

[0060] Because the internal environment of concrete is relatively harsh, the microorganisms need to be further treated before solidification to transform them into spores, which can meet the needs of long-term mineralization. First, 1000mL of 3×10 7 After centrifugation of the cfu / mL Bacillus pasteurianus bacterial solution, the supernatant was poured out and the remaining precipitate was air-dried in an anhydrous state for 3 days. In order to accelerate the conversion of Bacillus pasteurianus into spores, the air-dried precipitate was placed in 100 mL of 0.1 mol / L MnCl2 solution (the volume ratio of bacterial solution to manganese chloride solution was 10:1) and soaked for 3 hours. Then, it was heated in an 80°C water bath for 15 minutes and resuspended in 800 mL of normal saline (the volume ratio of bacterial solution to normal saline was 5:4) to obtain a spore suspension.

[0061] (3) Zeolite impregnation modification:

[0062] Since zeolite pores and channels contain certain impurities, the impurities in the channels can be removed through acidic solution impregnation modification, the porosity can be increased, and the specific surface area can be increased. At the same time, a certain diffusion force can be generated, and the adsorption capacity can be further improved. Therefore, the zeolite after impregnation modification can provide a wider living space for microorganisms.

[0063] The modification reagent used was 0.4 mol / L HCl solution. The modification method was as follows:

[0064] At room temperature, the zeolite was washed and dried, and then immersed in a 0.4 mol / L HCl solution for 6 h (the mass ratio of zeolite to modification reagent was 1:2). Then, it was placed in a shaker (160 r / min, 20 ° C). After 24 hours, it was taken out, the supernatant was poured out, filtered, and repeatedly washed with deionized water. It was dried in an oven at 105-110 ° C to constant weight, cooled to room temperature for use, and the modification was completed.

[0065] (4) Immobilization of microorganisms:

[0066] 400 g of the modified zeolite was mixed with 900 mL of spore suspension (mass ratio of 4:9) and placed in a shaker (100 r / min, 10° C.). After uniform mixing for 4 hours, the mixture was vacuum-fixed at -0.08 MPa for 20 minutes using a vacuum pump. The zeolite with the immobilized microorganisms was then taken out and placed in an oven (50° C., 60 minutes). The microbial immobilization was completed, and the concrete reinforcing particles of the present invention were obtained.

[0067] The morphology of zeolite particles after vacuum immobilization of microorganisms can be found in Figure 3 .

[0068] Example 2

[0069] This embodiment provides a concrete reinforcement particle. The raw materials and preparation method thereof differ from those of Example 1 in that the modification agent selected for zeolite impregnation modification is sodium hydroxide solution. The modification method is as follows:

[0070] At room temperature, the zeolite was washed and dried, then immersed in 0.4 mol / L sodium hydroxide solution for 6 hours, and then placed in a shaker (160 r / min, 20 ° C) for 24 hours. After being taken out, the supernatant was poured out, filtered and repeatedly washed with deionized water, dried in an oven at 105-110 ° C to constant weight, cooled to room temperature for use, and the modification was completed.

[0071] Example 3

[0072] This embodiment provides a concrete reinforcement particle. The raw materials and preparation method thereof differ from those of Example 1 in that the modification agent selected for zeolite impregnation modification is H2SO4 solution. The modification method is as follows:

[0073] At room temperature, the zeolite was washed and dried, then immersed in 0.3 mol / L H2SO4 solution for 7 hours, and then placed in a shaker (160 r / min, 20 ° C) for 24 hours. After being taken out, the supernatant was poured out, filtered and repeatedly washed with deionized water, dried in an oven at 105-110 ° C to constant weight, cooled to room temperature for use, and the modification was completed.

[0074] Example 4

[0075] This embodiment provides a concrete reinforcement particle. The raw materials and preparation method thereof differ from those of Example 1 in that the modification agent selected for zeolite impregnation modification is HNO3 solution. The modification method is as follows:

[0076] At room temperature, the zeolite was washed and dried, then immersed in 0.5 mol / L HNO3 solution for 5 h, then placed in a shaker (160 r / min, 20 ° C) for 24 h, taken out, the supernatant was poured out, filtered and repeatedly washed with deionized water, dried in an oven at 105-110 ° C to constant weight, cooled to room temperature for use, and the modification was completed.

[0077] Comparative Example 1

[0078] This comparative example provides a concrete reinforcing particle. The raw materials and preparation method thereof differ from those of Example 1 in that natural zeolite is directly used for microbial immobilization without modification.

[0079] Experimental Example 1

[0080] In this experimental example, the microbial immobilization and mineralization effects of concrete reinforcing particles modified with different modifying agents (including the concrete reinforcing particles prepared in Example 1) and the concrete reinforcing particles prepared in Comparative Example 1 were compared. The specific methods are as follows:

[0081] (1) Acid and alkali impregnation modification part:

[0082] Modification reagents: 0.2mol / L, 0.4mol / L, 0.6mol / L HCl solutions and 0.2mol / L, 0.4mol / L, 0.6mol / L NaOH solutions.

[0083] Modification method: At room temperature, take 500g of zeolite each, with the initial zeolite particle size of 1.0-2.0mm. After washing and drying the zeolite, place it in 1000mL of modification reagent and immerse it for 6 hours (the mass ratio of zeolite to modification reagent is 1:2). Then place it in a shaker (160r / min, 20℃). After 24 hours, take it out, pour out the supernatant, filter it, and repeatedly wash it with deionized water. Dry it in an oven at 105-110℃ to constant weight, cool it to room temperature and use it. The modification is complete.

[0084] Seven groups of samples were used in the experiment. Group a consisted of natural zeolite, serving as the control group; groups b1, b2, and b3 were modified by impregnation with HCl solutions of varying concentrations; and groups c1, c2, and c3 were modified by impregnation with NaOH solutions of varying concentrations. See Table 2 for details.

[0085] Table 2 Sample impregnation modification parameters

[0086] serial number Zeolite particle size (mm) Modification reagents a 1.0-2.0 Unmodified b1 1.0-2.0 0.2 mol / L HCl solution b2 1.0-2.0 0.4 mol / L HCl solution b3 1.0-2.0 0.6 mol / L HCl solution c1 1.0-2.0 0.2 mol / L NaOH solution c2 1.0-2.0 0.4 mol / L NaOH solution c3 1.0-2.0 0.6 mol / L NaOH solution

[0087] (2) Preparation of spore suspension

[0088] 1000mL of a 3×10 7 After centrifugation of the cfu / mL Bacillus pasteurianus bacterial solution, the supernatant was poured out and the remaining precipitate was air-dried in an anhydrous state for 3 days. In order to accelerate the conversion of Bacillus pasteurianus into spores, the air-dried precipitate was placed in 100mL of 0.1mol / L MnCl2 solution (the volume ratio of bacterial solution to manganese chloride solution was 10:1) and soaked for 3h. Then, it was heated in an 80℃ water bath for 15min and resuspended in 800mL of normal saline (the volume ratio of bacterial solution to normal saline was 5:4) to obtain a spore suspension.

[0089] (3) Comparison of microbial immobilization and mineralization weight gain effects:

[0090] 400 g of each modified zeolite group and natural zeolite were weighed respectively, and 900 mL of spore suspension was measured respectively (the mass ratio of zeolite to bacterial liquid was 4:9). The zeolite and spore suspension were mixed and placed in a shaker (100 r / min, 24°C) for uniform mixing for 4 h, and then vacuum-fixed at -0.08 MPa for 20 min using a vacuum pump. After immobilization, the zeolite needs to be taken out and placed in an oven (50°C, 60 min). After drying, the mass of the zeolite is measured and recorded as m1. This stage is the microbial immobilization stage, and the immobilization weight gain is recorded as Δm1. Then, the immobilized zeolite particles are placed in a beaker, and 900 mL of 0.5 mol / L calcium chloride solution is added (the volume ratio of calcium chloride solution to bacterial liquid is 1:1). At the same time, in order to provide sufficient nutrients, 2.0 g of urea, 0.5 g of yeast extract, and 1.0 g of trypsin are added. Finally, 7 groups of samples a, b1, b2, b3, c1, c2, and c3 are placed in a shaker (150 r / min, 20°C). After 50 hours, the zeolite particles are taken out and the final mass is measured after drying, recorded as m2. This stage is the microbial mineralization stage, and the mineralization weight gain is recorded as Δm2. Δm1 and Δm2 are calculated according to the following formulas:

[0091] Δm1=m1-24;

[0092] Δm2=m2-m1.

[0093] Wherein, Δm1 is the weight gain of modified zeolite in the solidification stage, g;

[0094] Δm2 is the weight gain of modified zeolite during the mineralization stage, g;

[0095] m1 is the mass of modified zeolite after microbial immobilization, g;

[0096] m2 is the mass of modified zeolite after microbial mineralization, g;

[0097] After 50 hours of mineralization, the weight gain of the seven groups of zeolites was measured. The measurement results are shown in Table 3.

[0098] Table 3 Weight gain of modified zeolite

[0099] serial number <![CDATA[Δm1(g)]]> <![CDATA[Δm2(g)]]> a 0.72 0.57 b1 1.39 0.64 b2 1.58 0.66 b3 1.72 0.59 c1 0.81 0.61 c2 0.96 0.60 c3 1.08 0.58

[0100] Table 3 shows that compared to natural zeolite, modified zeolite (zeolite modified by impregnation with acidic or alkaline solutions) has a higher microbial loading capacity and better mineralization weight gain. In particular, the 0.4 mol / L acid-modified zeolite doubles the microbial loading capacity of natural zeolite and exhibits the best mineralization weight gain of all groups.

[0101] Example 5

[0102] This embodiment provides a concrete comprising the concrete reinforcing particles (modified zeolite particles immobilized with microorganisms) described in Example 1. The composition and raw material ratio of the concrete are shown in Table 4:

[0103] Table 4 Concrete mix ratio (Kg / m 3 )

[0104]

[0105]

[0106] Note: BEC m In the figure, B stands for microbial concrete and the suffix m stands for the modification of zeolite in the concrete.

[0107] In Table 4, the zeolite is the concrete reinforcing particles described in Example 1.

[0108] Comparative Example 2

[0109] This comparative example provides a conventional concrete without adding concrete reinforcing particles. Its composition and raw material mix ratio are shown in Table 5:

[0110] Table 5 Concrete mix ratio (Kg / m 3 )

[0111]

[0112] Comparative Example 3

[0113] This comparative example provides a concrete comprising the concrete reinforcing particles (natural zeolite particles immobilized with microorganisms) described in Comparative Example 1. The composition and raw material mix ratio of the concrete are shown in Table 6:

[0114] Table 6 Concrete mix ratio (Kg / m 3 )

[0115]

[0116] Note: In BEC, B stands for microbial concrete and no suffix m means the zeolite in the concrete is not modified.

[0117] In Table 6, the zeolite used is the concrete reinforcing particles described in Comparative Example 1.

[0118] Experimental Example 2

[0119] This experimental example conducted a concrete crack repair test on the concrete of Example 5 and the concrete of Comparative Examples 2-3. The test method is as follows:

[0120] (1) Concrete preparation:

[0121] During the concrete mixing process of Samples I and III, zeolite was added at a rate of 40% to replace the fine aggregate river sand (the amount of river sand in Table 5 is 786 kg / m 3 Tables 4 and 6 have replaced the river sand in Table 5 by 40% of the fine aggregate. The amount of river sand after replacement is 471.6 kg / m 3 The zeolite dosage is 314.4 kg / m 3 ). Specific preparation method: Before formal mixing, pre-mix cement mortar with the same water-cement ratio, hang the inner wall of the mixer on the mortar, and then discharge the remaining material. Then add coarse aggregate stone and fine aggregate river sand into the mixer (speed 20r / min) and stir for 2 minutes. At the same time, calcium chloride and nutrients required for microbial growth (urea, trypsin, yeast extract) are fully dissolved in water at a mass ratio of 1:5. Then the solution and zeolite are evenly mixed to ensure that the surface of the zeolite particles is wet and coated with sufficient nutrients and calcium sources for mineralization and crystallization. After mixing evenly, add the coated zeolite particles to the cement and fly ash, and stir them together with the aggregate. After stirring for 30 seconds, add the remaining mixing water (the water reducer has been dissolved in the water) in batches according to the mix ratio. The mixing time is 3 minutes. Pour the mixed concrete mixture onto a steel plate and manually stir it for 2 minutes to make it uniform.

[0122] Concrete preparation method for Sample II: Before formal mixing, pre-mix cement mortar with the same water-cement ratio, coat the inner wall of the mixer with mortar, and then discharge the remaining material. Then, add the coarse aggregate stone and fine aggregate river sand into the mixer (speed 20r / min) and stir for 2 minutes. After mixing evenly, add it to the cement and fly ash and stir together with the aggregate. After stirring for 30 seconds, add the remaining mixing water (the water reducer has been dissolved in the water) in batches according to the mix ratio, and mix for 3 minutes. Pour the mixed concrete mixture onto a steel plate and manually stir it for 2 minutes to make it uniform.

[0123] The concrete prepared from the above three groups of samples was respectively poured into a cubic mold with a side length of 100 mm and cured under standard curing conditions (temperature 20°C ± 3°C, relative humidity above 90%) to 28 days to obtain three groups of concrete test blocks.

[0124] (2) Compressive strength recovery rate test:

[0125] To examine the strength recovery of the three groups of concrete specimens described above, compressive strength recovery tests were conducted on these specimens. Cracks were created in the cured concrete specimens using a WHY-2000 microcomputer-controlled pressure testing machine, and initial compressive strength was measured. The crack width was controlled to be less than 0.60 mm. The cracks were then self-repaired using an air-water cycle curing method for 28 days.

[0126] After 28 days of curing, the specimens were removed and the strength of the repaired concrete was retested. The strength of the repaired concrete was compared with its original 28-day compressive strength, and the compressive strength recovery rate (R) was calculated using the following formula.

[0127]

[0128] Where, R represents the strength recovery rate of concrete; f c ' c Indicates the strength of concrete after crack repair, MPa; f cc Indicates the cubic compressive strength of concrete at 28 days, MPa.

[0129] (3) Water absorption test:

[0130] After repairing, remove the specimen and dry it in an oven until constant weight is reached. Weigh the specimen and record its mass as m0. Cool the specimen to room temperature and place it in a water tank. Add water until the water level is 30 mm above the specimen, maintaining a constant temperature of 20°C. After 24 hours, remove the specimen, wipe off any surface moisture with a wrung-out damp cloth, and weigh the specimen as m1. Calculate the final water absorption w using the following formula.

[0131]

[0132] Where w represents the water absorption rate of the specimen for 24 hours; m0 represents the initial mass of the specimen, kg; m1 represents the mass of the specimen after immersion in water for 24 hours, kg.

[0133] The compressive strength, compressive strength recovery rate and water absorption rate of each group of specimens after testing are shown in Table 7.

[0134] Table 7 Compressive strength and water absorption of specimens

[0135]

[0136]

[0137] (4) Analysis of the relationship between crack width and crack repair rate of different concrete specimens:

[0138] When the zeolite content is 40%, the relationship between the crack width and the repair rate of the concrete specimens of groups I, II, and III after 28 days of repair is as follows: Figure 4 shown.

[0139] Depend on Figure 4 It can be seen that after zeolite modification, the immobilization efficiency increased significantly, as did the amount of Bacillus pasteurianus mineralized. The maximum crack width of Group I specimens that could be completely repaired was 0.50 mm. Natural zeolite, due to its relatively low immobilized microorganisms and mineralized content, exhibited relatively poor crack repair performance. The maximum crack width that could be completely repaired in Group III specimens was 0.30 mm, which was lower than that of the modified zeolite concrete specimens. However, the repair performance was significantly higher than that of the natural, ordinary concrete (Group II specimens).

[0140] (5) Comparative analysis of crack repair effects:

[0141] During the self-repair maintenance period, take photos to record the crack repair situation. Figure 5 and Figure 6 .

[0142] Figure 5 For BEC m Comparative photos of the 28-day repair process of the cracks in the two groups of concrete specimens ( Figure 5 The photo on the left is BEC m group, the photo on the right is the BEC group). Figure 5 It can be seen that modified zeolite BEC m A relatively large amount of white crystals were produced at the cracks of the specimens, and the crack repair rate and final repair effect were correspondingly high; the crystallization rate of the cracks in 7-14 days was faster than that of the natural zeolite specimens, and the final repair rate in 28 days could reach up to 100%. The cracks were completely and densely filled with white deposited crystals, and the repair effect was more significant.

[0143] Figure 6 For BEC m SEM image analysis results of different positions of the two groups of concrete specimens after the cracks were repaired for 28 days. Figure 6 From Figures (a) and (b), we can see that modified zeolite BEC m The cracks of the test block are almost completely surrounded by white crystals, while the cracks of the natural zeolite BEC test block have relatively few crystals around them, and the surface is still partially exposed, so the mineralization effect is relatively poor. Figure 6 In Figure (c), it can be observed that: modified zeolite BEC mThe crystallization of the test block has covered the surrounding coarse aggregate and made the structure more compact, with obvious crystallization effect. Figure 6 In Figure (d), it can be observed that: modified zeolite BEC m The white crystalline particles of the test block are obvious, square-shaped particles with small particle size, the largest of which is close to 20μm.

[0144] (6) FTIR analysis of white crystals in cracks:

[0145] After 28 days of self-repair and curing, the white crystals in the cracks were analyzed by FTIR. The results are shown in Figure 7 .

[0146] Figure 7 For BEC m The FTIR analysis results of the white crystals in the concrete specimen after 28 days of repair showed three strong bands (1420 cm -1 , 876cm -1 and 711cm -1 Carbonate rocks have three to four strong bands in the infrared spectrum. -1 , 876cm -1 The zone is the characteristic of carbonate rock identification, 711cm -1 Zoning is characteristic of calcite in various carbonate rocks. The spectral analysis shows that the white precipitate in the cracks is calcite, which matches the mineralization crystals of Bacillus pasteurianus.

[0147] In summary, the concrete-reinforcing particles of the present invention help improve the compressive strength of concrete after curing and can automatically repair cracks in concrete specimens. Compared to the comparative example, concrete specimens prepared with the concrete-reinforcing particles of the present invention exhibited higher compressive strength and recovery rate after 28 days of self-repair, and lower 24-hour water absorption. This demonstrates that the concrete-reinforcing particles provided by the present invention have excellent concrete reinforcement and self-repair effects.

[0148] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. Concrete reinforcing particles, characterized in that, The concrete reinforcing particles are modified zeolite particles loaded with microorganisms; the microorganisms include Bacillus pasteurianus; the modified zeolite particles are obtained by impregnating and modifying natural zeolite particles with an acidic solution or an alkaline solution; the microorganisms are subjected to stress treatment; The coercive treatment methods include one or more of the following: (1) Place the microorganisms in a water-deficient environment for 2-5 days; (2) Soak the microorganisms in a 0.05-0.2 mol / L MnCl2 solution for 1-5 hours; (3) Place the microorganisms under stress conditions at 70-85°C for 10-20 minutes.

2. The concrete reinforcing particles according to claim 1, characterized in that: The modified zeolite particles are obtained by impregnating natural zeolite particles with an acidic solution; the H + The concentration is 0.2-0.6 mol / L, and the time for the immersion modification is 4-8 hours.

3. The concrete reinforcing particles according to claim 1, characterized in that: The acidic solution is a 0.3-0.5 mol / L HCl solution; and the immersion modification time is 5-7 hours.

4. The concrete reinforcing particles according to any one of claims 1 to 3, characterized in that: The microorganism is in spore form.

5. The concrete reinforcing particles according to any one of claims 1 to 3, characterized in that: The method for immobilizing microorganisms on modified zeolite particles comprises the following steps: S1. Shake and mix the modified zeolite particles and the microbial suspension at a mass ratio of 1:(1.5-3) for 3-6 hours to obtain a mixed material; S2. The mixed material described in step S1 is placed under vacuum solidification at 0.06-0.1 MPa for 15-30 minutes to obtain a solid material; S3. Drying the zeolite in the solid-loaded material in step S2 at 40-60° C. for 30-120 min to obtain modified zeolite particles loaded with microorganisms.

6. The concrete reinforcing particles according to claim 4, characterized in that: The method for immobilizing microorganisms on modified zeolite particles comprises the following steps: S1. Shake and mix the modified zeolite particles and the microbial suspension at a mass ratio of 1:(1.5-3) for 3-6 hours to obtain a mixed material; S2. The mixed material described in step S1 is placed under vacuum solidification at 0.06-0.1 MPa for 15-30 minutes to obtain a solid material; S3. Drying the zeolite in the solid-loaded material in step S2 at 40-60° C. for 30-120 min to obtain modified zeolite particles loaded with microorganisms.

7. The concrete reinforcing particles according to claim 5, characterized in that: The concentration of the microbial suspension in step S1 is 0.5×10 7 cfu / mL-5×10 7 cfu / mL.

8. The concrete reinforcing particles according to claim 6, characterized in that: The concentration of the microbial suspension in step S1 is 0.5×10 7 cfu / mL-5×10 7 cfu / mL.

9. Concrete, characterized in that The concrete reinforcing particles according to any one of claims 1 to 8 are included.

10. The concrete according to claim 9, characterized in that: The mass proportion of the concrete reinforcing particles in the concrete is 5%-32.5%.

11. The concrete according to claim 9 or 10, characterized in that: The concrete further comprises at least one of calcium chloride, urea, tryptone and yeast extract.

12. Use of the concrete reinforcing particles according to any one of claims 1 to 8, or the concrete according to any one of claims 9 to 11 in crack repair.

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