Hollow fiber mediated bio-concrete carbon sequestration fibers, methods of making, and concrete

Abstract

The present application relates to the technical field of building materials and microbial mineralization, and discloses a hollow fiber-mediated bio-concrete carbon fixation fiber, a preparation method and concrete. The carbon fixation fiber comprises a fiber carrier providing a transport path and a diffusion channel for CO2, and a carbon fixation microorganism loaded on the fiber carrier, and the carbon fixation fiber is used as a reinforcing fiber in concrete. The present application forms a carbon fixation fiber with a stable microorganism-carrier composite system by loading the carbon fixation microorganism on the surface of the fiber carrier with a hollow structure. The carbon fixation fiber is applied to concrete to provide a transport path and a diffusion channel for CO2 in the concrete matrix through hollow mediation, and the carbon fixation microorganism is oriented and mineralized at the interface between the reinforcing fiber and the concrete, thereby improving the carbon fixation amount and strengthening the interfacial bonding force, and a low-carbon concrete with high CO2 sequestration capacity and excellent mechanical properties is prepared, which provides a new material and a new process for the carbon neutralization goal of the building industry.

Description

TECHNICAL FIELD

[0001] The application relates to the technical field of building materials and microbial mineralization, and particularly relates to a hollow fiber-mediated bio-concrete carbon fixation fiber, a preparation method and concrete. BACKGROUND

[0002] The climate crisis caused by the rapid increase of global carbon emissions poses a serious threat to the ecological environment. The construction industry, as a key source of carbon emissions, has seen a continuous increase in the annual output of its core material, concrete, which is expected to exceed 5.5 billion tons in 2025. The decomposition of carbonates and fuel combustion in the production process of cement contribute about 8% of global CO2 emissions (annual emissions of 2.8 billion tons), and the overexploitation of river sand resources exacerbates the ecological pressure. Under this background, the combination of sea sand concrete (SWSSC) and fiber-reinforced polymer (FRP) bars has become a solution for coastal engineering. However, the inherent high alkaline environment (pH>12.5) of concrete easily leads to the deterioration of the FRP bar-concrete interface, which restricts its application.

[0003] The International Energy Agency (IEA) points out that even if renewable energy transformation is achieved, 1 billion to 10 billion tons of CO2 need to be treated annually through carbon capture, utilization and storage (CCUS) technology by 2050 to achieve the net zero emission target. The carbonation curing technology of concrete can not only permanently fix carbon, but also significantly reduce the pH value of the pore solution to 8-10, thereby completely eliminating the risk of alkaline corrosion of FRP bars. At the same time, this technology optimizes the microstructure of concrete, improves its mechanical properties and durability, and becomes a key path for the low-carbon transformation of building materials.

[0004] However, the current carbonation curing technology faces two major bottlenecks: first, the dense structure of concrete limits the diffusion of CO2, resulting in a carbon fixation efficiency usually less than 25%; second, the technology generally relies on high-pressure or high-concentration CO2 sources, making the carbon capture-compression-transportation chain highly energy-consuming, which is contrary to the principle of carbon neutrality. Therefore, biological catalytic carbon fixation technology has attracted attention due to its mild reaction conditions. However, the direct bacteria mixing method has key obstacles: biological enzymes are easily inactivated in a high-alkaline environment (pH>12.5), and the CO2 transport efficiency inside the concrete is limited. SUMMARY

[0005] In view of the fact that the physical limitation of CO2 internal transmission in the existing concrete carbonation carbon sequestration technology is still difficult to overcome, and the carbon sequestration-enhanced performance is split, the hollow fiber mediated microbial concrete carbon sequestration fiber is provided, wherein the fiber carrier provides a transport path and a diffusion channel for CO2, significantly reducing the diffusion resistance of CO2; the fiber carrier itself is used as the CO2 transport path to improve the CO2 transmission efficiency; the carbon sequestration microorganism loaded on the fiber carrier is oriented mineralization at the fiber-matrix interface, and the interface bonding is strengthened, so that the problem of split of carbon sequestration-enhanced performance is solved, and the specific scheme is as follows:

[0006] The hollow fiber mediated biological concrete carbon sequestration fiber comprises a fiber carrier providing a transport path and a diffusion channel for CO2, and a carbon sequestration microorganism loaded on the fiber carrier.

[0007] The fiber carrier is a hollow structure.

[0008] Preferably, the fiber carrier is a natural hollow fiber and / or a synthetic hollow fiber.

[0009] Preferably, the carbon sequestration microorganism has the characteristics of accelerating the hydration of CO2 to generate carbonate and dissolving the alkaline substances in the concrete matrix to form carbonate precipitates by secreting organic acid.

[0010] The carbon sequestration microorganism is Bacillus mucilaginosus.

[0011] The preparation method of the hollow fiber mediated biological concrete carbon sequestration fiber is applied to the preparation of the hollow fiber mediated biological concrete carbon sequestration fiber, and the preparation method comprises the following steps:

[0012] S1, a natural hollow fiber and / or a synthetic hollow fiber is used to prepare a hollow fiber yarn;

[0013] S2, the hollow fiber yarn is pretreated, and the pretreated hollow fiber yarn is sequentially subjected to alkali modification treatment, impurity removal and drying to obtain a fiber carrier, wherein the fiber carrier has the characteristics of improving the antistatic property and the flame retardancy of the hollow fiber yarn while maintaining the original mechanical properties of the hollow fiber yarn;

[0014] S3, the fiber carrier is subjected to surface treatment to increase its roughness;

[0015] S4, the fiber carrier is soaked in a carbon sequestration microorganism culture solution to obtain the hollow fiber mediated biological concrete carbon sequestration fiber;

[0016] The fiber volume content of the fiber carrier is 0.5 kg / m 3 1.5 kg / m 3 .

[0017] The concentration of the carbon sequestration microorganism culture solution is 2×103 CFU / m~2×10 9 CFU / ml, constant temperature immersion for 12h.

[0018] Preferably, the alkali treatment in S2 is by soaking in an organic amine solution at room temperature for 12h.

[0019] The organic amine solution is an ethanol amine solution.

[0020] Preferably, the pretreatment process of the hollow fiber in S2 includes soaking in an alkali solution and then washing with clean water; the impurity removal process in S2 includes washing with an alcohol solution and then repeatedly washing with clean water.

[0021] Preferably, the alkali solution is a 80% sodium hydroxide solution, and the soaking is at 80℃ for 24h.

[0022] The alcohol solution is a 50% anhydrous ethanol solution.

[0023] The network-embedded matrix forms a rapid CO2 transport path, realizing gradient mineralization in the deep layer.

[0024] In view of the existing carbonation carbon sequestration technology of concrete, the application provides a hollow fiber-mediated biological concrete, and a hollow fiber-mediated biological concrete carbon fiber is embedded in the concrete matrix as a reinforcing base to prepare a carbon sequestration concrete with carbon sequestration and mechanical property improvement, and the specific scheme is as follows:

[0025] A hollow fiber-mediated biological concrete, the carbon sequestration concrete comprises: a concrete matrix and a reinforcing fiber embedded in the concrete matrix.

[0026] The reinforcing fiber is the hollow fiber-mediated biological concrete carbon fiber.

[0027] The hollow fiber-mediated biological concrete carbon fiber provides a transport path and diffusion channel for CO2 in the concrete matrix and provides a survival environment for the loaded carbon sequestration microorganism on one hand, and on the other hand, the carbon sequestration microorganism loaded therein is oriented mineralization at the interface between the reinforcing fiber and the concrete, thereby increasing the carbon sequestration amount and strengthening the interface bonding.

[0028] Preferably, the concrete matrix is mixed by steel slag, cementitious material, sand aggregate and water.

[0029] Preferably, the carbonation carbon sequestration method of the carbon sequestration concrete comprises:

[0030] S1, preparing a concrete matrix material;

[0031] S2, the hollow fiber mediated bio-concrete carbon fiber is added to the concrete base material, stirred, and evenly dispersed in the concrete base material, and poured into the corresponding model for solidification;

[0032] S3, the solidified concrete is respectively placed in a carbonation curing box with 50% CO2, 50% RH and 25℃ for 7d, 14d and 28d.

[0033] Compared with the prior art, the technical scheme of the present application has the following beneficial effects:

[0034] The fiber carrier in the present application is a hollow structure that provides a diffusion channel for CO2, and the fiber carrier itself serves as a CO2 transport path, which provides a living environment for the carbon fixation microorganism, to solve the physical limitation of CO2 transmission in the prior art; the carbon fixation microorganism accelerates the hydration of CO2 to generate carbonate on the one hand, and secretes organic acid to dissolve Ca 2+ / Mg 2+ in the steel slag on the other hand, to form carbonate precipitation; to achieve directional mineralization at the fiber-matrix interface, strengthen the interface bonding, and solve the problem of the split of carbon fixation and performance enhancement;

[0035] Preferably, the natural hollow fiber is sisal fiber, and the synthetic hollow fiber is polypropylene fiber, because the cavity diameter of the sisal / polypropylene fiber is 3~4 orders of magnitude larger than the capillary pore of the concrete, which significantly reduces the CO2 diffusion resistance; and the fiber network is embedded in the matrix to form a rapid CO2 transport path, achieving gradient mineralization in the deep area;

[0036] In the preparation of the hollow fiber mediated bio-concrete carbon fiber, the hollow fiber filaments are first alkali modified, and the surfaces of the natural fiber (sisal fiber) and the synthetic fiber (polypropylene fiber) are subjected to high-temperature alkali etching to enhance the roughness of the surfaces, so that the lumen pore size of the PP fiber surface is increased; the modified hollow fiber loads the carbon fixation microorganism, which provides a living environment for the fluorocarbon microorganism, and the hollow structure of the fiber serves as a high-speed diffusion channel for CO2, accelerating the carbonation reaction and increasing the carbon fixation amount; at the same time, the bacteria are directionally mineralized at the fiber-matrix interface, strengthening the interface bonding, thereby promoting the transmission of CO2 and the improvement of the carbonation degree during the carbonation curing process. Then the fiber is immersed in the bacteria solution of the carbon fixation microorganism to load the carbon fixation microorganism on the surface of the fiber carrier, thereby preparing the hollow fiber mediated bio-concrete carbon fiber.

[0037] The present application solves the problem of limited carbonation depth of CO2 in concrete, and through innovative theory and method, the modified hollow fiber and Bacillus mucilaginosus are combined to improve the mechanical properties of carbonation curing concrete while achieving carbonation degree and carbon sequestration amount; it has important theoretical significance and practical application value; the technology provides a scalable implementation of low-carbon material solution for building, marine engineering and CCUS industry. 2+ / Mg 2+ The matrix of the concrete is mixed by steel slag, cementitious material, sand aggregate and water, and the steel slag is used as an auxiliary cementitious material to replace cement, and the calcium and magnesium rich minerals (CaO, MgO) thereof provide a high activity ion source for carbonation reaction, and at the same time realizes the resource utilization of solid waste.

[0038] The present application tests the carbonation degree and mechanical properties under different carbonation ages by preparing specimens separately mixed with bacteria and hollow fibers, and fiber-loaded hollow fibers, and uses saturated calcium hydroxide solution for curing as a control to analyze the improvement of fiber-loaded bacteria under carbonation effect, and prepares carbon sequestration concrete with carbon sequestration and mechanical property improvement.

[0039] The present application not only solves the problem of limited carbonation depth of CO2 in concrete, but also through innovative theory and method, the modified hollow fiber and Bacillus mucilaginosus are combined to improve the mechanical properties of carbonation curing concrete while achieving carbonation degree and carbon sequestration amount; it has important theoretical significance and practical application value; the technology provides a scalable implementation of low-carbon material solution for building, marine engineering and CCUS industry. BRIEF DESCRIPTION OF DRAWINGS

[0040] Figure 1 Flow chart of the hollow fiber loaded bacteria enhanced carbonation and carbon sequestration method in the present application;

[0041] Figure 2 Schematic diagram of fiber treatment and specimen forming and curing in the embodiment of the present application;

[0042] Figure 3 Microstructure diagram of the hollow fiber yarn, fiber carrier and fiber carrier loaded with microorganisms prepared in the embodiment of the present application;

[0043] Figure 4 Schematic diagram of carbonation degree of concrete at different ages in the embodiment of the present application;

[0044] Figure 5The influence law diagram of the compressive strength of different ages (7d, 14d, 28d) under different factors in the embodiment of the present application is shown.

[0045] Figure 6 The influence law diagram of the flexural strength of 28d under different factors in the embodiment of the present application is shown.

[0046] Figure 7 The XRD test result diagram of the micro performance of 28d under different factors in the embodiment of the present application is shown.

[0047] Figure 8 The TG test result diagram of the micro performance of 28d under different factors in the embodiment of the present application is shown. DETAILED DESCRIPTION

[0048] The technical solutions in the embodiments of the present application will be clearly and completely described in combination with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the protection scope of the present application.

[0049] Embodiment 1

[0050] The hollow fiber mediated bio-concrete carbon fiber includes: a fiber carrier providing a transport path and a diffusion channel for CO2, and a carbon fixation microorganism loaded on the fiber carrier.

[0051] The fiber carrier is a hollow structure, wherein the fiber carrier is a hollow fiber yarn prepared from natural hollow fibers and / or synthetic hollow fibers.

[0052] The carbon fixation microorganism has the characteristics of accelerating the hydration of CO2 to generate carbonate and dissolving alkaline substances in the concrete matrix to form carbonate precipitates by secreting organic acids.

[0053] The carbon fixation microorganism is Bacillus mucilaginosus.

[0054] Embodiment 2

[0055] The preparation method of the hollow fiber mediated bio-concrete carbon fiber includes:

[0056] S1, a hollow fiber yarn is prepared from natural hollow fibers and / or synthetic hollow fibers, wherein the natural hollow fibers include but are not limited to sisal fibers, and the synthetic hollow fibers include but are not limited to polypropylene fibers (pp fibers); the hollow fiber yarn in the embodiment is a mixed hollow sisal fiber yarn and a hollow PP fiber yarn with a length of 15mm.

[0057] S2, the length of 15 mm, the volume of 0.5 kg / m 3 The mixed hollow sisal fiber and hollow PP fiber are pretreated (specifically, the hollow fiber is put into a sodium hydroxide cleaning solution with a concentration of 80%, soaked at 80°C for 24h, and then cleaned with clean water), and the pretreated hollow fiber is sequentially subjected to alkali modification treatment (soaked in an organic amine solution for 12h for alkali modification of the hollow fiber), cleaned twice with anhydrous ethanol solution with a concentration of 50%, and finally cleaned repeatedly with clean water to remove impurities, and then naturally dried to obtain a fiber carrier, which has the properties of improving the antistatic property and flame retardancy of the hollow fiber while maintaining the original mechanical properties of the hollow fiber;

[0058] S3, the fiber carrier is surface treated (specifically, high-temperature alkali etching) to increase its roughness;

[0059] S4, the modified hollow fiber is put into a carbon fixation microbial culture solution (i.e., a Bacillus mucilaginosus concentrated solution with a concentration of 2×10 3 CFU / m), and the container is soaked in a thermostat for 12h to obtain a hollow fiber-mediated bioconcrete carbon fixation fiber, i.e., a sisal fiber and a PP fiber loaded with Bacillus mucilaginosus.

[0060] Example 3:

[0061] The preparation method of the hollow fiber-mediated bioconcrete carbon fixation fiber comprises:

[0062] S1, natural hollow fibers and synthetic hollow fibers are used to prepare hollow fiber, wherein the natural hollow fibers include but are not limited to sisal fibers, and the synthetic hollow fibers include but are not limited to polypropylene fibers (PP fibers); in this embodiment, the hollow fiber is a mixed hollow sisal fiber and a hollow PP fiber with a length of 15mm;

[0063] S2, the length of 15 mm, the volume of 1.0 kg / m 3 The mixed hollow sisal fiber and hollow PP fiber are pretreated (specifically, the hollow fiber is put into a sodium hydroxide cleaning solution with a concentration of 80%, soaked at 80°C for 24h, and then cleaned with clean water), and the pretreated hollow fiber is sequentially subjected to alkali modification treatment (soaked in an organic amine solution for 12h for alkali modification of the hollow fiber), cleaned twice with anhydrous ethanol solution with a concentration of 50%, and finally cleaned repeatedly with clean water to remove impurities, and then naturally dried to obtain a fiber carrier, which has the properties of improving the antistatic property and flame retardancy of the hollow fiber while maintaining the original mechanical properties of the hollow fiber;

[0064] S3, the fiber carrier is surface treated (specifically, high-temperature alkaline etching) to increase its roughness;

[0065] S4, the modified hollow fiber filaments are placed in a carbon-fixing microbial culture medium (i.e., a concentration of 2×10⁻⁶). 6 The container was soaked in a constant temperature incubator for 12 hours after obtaining a CFU / ml concentrated solution of Bacillus mucilaginosus to form hollow fiber-mediated bio-concrete carbon fiber, which is sisal fiber and PP fiber loaded with Bacillus mucilaginosus.

[0066] Example 4:

[0067] A method for preparing hollow fiber-mediated bio-concrete-fixed carbon fibers, the method comprising:

[0068] S1, hollow fiber filaments are prepared using natural hollow fibers and / or synthetic hollow fibers, wherein the natural hollow fibers include, but are not limited to, sisal fibers, and the synthetic hollow fibers include, but are not limited to, polypropylene fibers (PP fibers); in this embodiment, the hollow fiber filaments are a mixture of hollow sisal fiber filaments and hollow PP fiber filaments with a length of 15mm.

[0069] S2, obtained from S1, has a length of 15 mm and a volumetric doping amount of 1.5 kg / m. 3 The mixed hollow sisal fiber filaments and hollow PP fiber filaments were pretreated (specifically, the hollow fiber filaments were immersed in an 80% sodium hydroxide cleaning solution at 80°C for 24 hours, and then rinsed with clean water). The pretreated hollow fiber filaments were then subjected to alkali modification treatment (immersed in an organic amine solution for 12 hours to modify the hollow fiber filaments with alkali), first washed twice with a 50% anhydrous ethanol solution, and finally repeatedly rinsed with clean water to remove impurities. After cleaning, the fiber carrier was naturally dried to obtain the fiber carrier. The fiber carrier can improve the antistatic and flame retardant properties of the hollow fiber filaments while maintaining the original mechanical properties of the hollow fiber filaments.

[0070] S3, the fiber carrier is surface treated (specifically, high-temperature alkaline etching) to increase its roughness;

[0071] S4, the modified hollow fiber filaments are placed in a carbon-fixing microbial culture medium (i.e., a concentration of 2×10⁻⁶). 9 The container was soaked in a constant temperature incubator for 12 hours after obtaining a CFU / ml concentrated solution of Bacillus mucilaginosus to form hollow fiber-mediated bio-concrete carbon fiber, which is sisal fiber and PP fiber loaded with Bacillus mucilaginosus.

[0072] Example 5:

[0073] A hollow fiber-mediated bio-carbon-fixing concrete, the carbon-fixing concrete comprising: a concrete matrix and reinforcing fibers embedded in the concrete matrix;

[0074] The reinforcing fiber is a hollow fiber-mediated biological concrete carbon sequestration fiber prepared in embodiments 2-4;

[0075] The hollow fiber-mediated biological concrete carbon sequestration fiber provides a transport path and diffusion channel for CO2 in the concrete matrix on the one hand, and provides a survival environment for the loaded carbon sequestration microorganism on the other hand. The carbon sequestration microorganism loaded on the reinforcing fiber is oriented and mineralized at the interface between the reinforcing fiber and the concrete, thereby increasing the amount of carbon sequestration and strengthening the interface bonding.

[0076] The concrete matrix is mixed by steel slag, cementitious material, sand and gravel aggregate, and water.

[0077] Embodiment 6:

[0078] A preparation method of a hollow fiber-mediated biological carbon sequestration concrete, specifically:

[0079] The concentration of Bacillus mucilaginosus in embodiments 2-4 is 2×10 3 CFU / ml, 2×10 6 CFU / ml and 2×10 9 CFU / ml, respectively; the volume fraction of sisal fiber and PP fiber is 0.5 kg / m 3 , 1 kg / m 3 , 1.5 kg / m 3 , respectively; other factors remain unchanged. The sisal fiber and PP fiber loaded with Bacillus mucilaginosus prepared respectively are mixed into the same concrete matrix, and the corresponding carbon sequestration concrete test pieces are prepared, wherein the specific preparation steps of the carbon sequestration concrete test pieces are as follows:

[0080] (1) The cementitious material and each sand and gravel aggregate are poured into a mixer for dry mixing;

[0081] (2) The water (concentrated bacterial solution) is mixed uniformly and then poured into the mixer until the mixture approaches the target fluidity;

[0082] (3) The sisal fiber and PP fiber loaded with Bacillus mucilaginosus prepared in embodiments 2-4 are added into the mixer in small amounts and multiple times respectively, so as to be uniformly dispersed;

[0083] (4) Stir for 2 min, and immediately pour out after rapid stirring to complete the preparation of the three kinds of concrete test pieces corresponding to embodiments 2-4, and complete the preparation process of the concrete test pieces.

[0084] Among them, the forming size of the concrete test piece is a cube test piece with a size of 100mm×100mm×100mm and a prism test piece with a size of 100mm×100mm×400mm.

[0085] Example 7:

[0086] As Figure 1 shown, the three concrete specimens prepared in Example 6 were demolded and placed in a carbonation curing box with 50% CO 2 , 50% RH, and 25℃ for carbonation curing, respectively, for 7d, 14d, and 28d; part of the mix proportion concrete specimens were placed in a calcium hydroxide solution for water curing for 28d as a control.

[0087] The following comparative examples analyze the effects of different fiber carriers, different concentrations of bacteria solution, different volume contents of sisal fibers, and different volume contents of PP fibers on the carbonation degree, mechanical properties, and microscopic properties of the prepared sea sand concrete specimens.

[0088] Comparative Example 1:

[0089] This comparative example analyzes the effects of different fiber carriers on the carbonation degree, mechanical properties, and microscopic tests of sea sand concrete. In this comparative example, cement, steel slag, sea sand, 5mm-20mm gravel, water, and water reducing agent are used as raw materials to prepare a concrete matrix material, and the fiber content is 1.5 kg / m 3 Different fiber carriers are soaked in concentrated bacteria solution with a bacteria concentration of 2x10 6 CFU / ml to obtain different hollow fiber-mediated bioconcrete carbon fixation fibers, which are then mixed into the concrete matrix material to prepare sea sand concrete specimens with different hollow fiber-mediated bioconcrete carbon fixation fibers of different fiber carriers. The raw material proportions of the sea sand concrete specimens with different fiber carriers are shown in Table 1:

[0090] Table 1 Raw material proportions of sea sand concrete specimens with different fiber carriers

[0091]

[0092] The preparation process of the sea sand concrete specimens with different hollow fiber-mediated bioconcrete carbon fixation fibers of different fiber carriers is as follows:

[0093] (1) Pour the cementitious materials and aggregates into the mixer and dry mix for 2 min;

[0094] (2) Mix the water reducing agent and water evenly and pour into the mixer, wet mix for 3 min, until the mixture reaches the target flow degree;

[0095] (3) Finally, add the bacteria solution, fibers, or fiber-loaded bacteria into the mixer, stir for 1 min, and then load into 100 mm x 100 mm x 100 mm and 100 mm x 100 mm x 400 mm molds to complete the preparation process.

[0096] After 24 h of specimen forming, the mold was removed, and the prepared 100 mm x 100 mm x 100 mm compressive specimens and 100 mm x 100 mm x 400 mm flexural specimens were placed in a carbonation curing box with 50% CO 2 , 50% RH, and 25°C for curing until 7 d, 14 d, and 28 d. Subsequently, the compressive strength test and carbonation degree test were performed on the specimens cured for 7 d, 14 d, and 28 d, the flexural strength test and microstructure test (X-ray diffraction analysis and thermogravimetric analysis) were performed on the specimens cured for 28 d, and the compressive strength test was performed on the specimens cured for 28 d in water.

[0097] The carbonation degree of the split test block cured for 28 d was tested using a 1% phenolphthalein solution. The carbonation degree was determined by calculating the ratio of the carbonation area of the colorless region to the total cross-sectional area.

[0098] The carbonation degree, mechanical properties, and microstructure test results were analyzed in coordination. The microstructure of the hollow fiber-mediated bioconcrete with different fiber carriers is shown in Figure 3 , the carbonation degree variation is shown in Figure 4 , the mechanical property variation is shown in Figure 5 (a) and Figure 6 , and the microstructure is shown in Figure 7 (a) and 8(a). The carbonation results of the hollow fiber-mediated bioconcrete with different fiber carriers are shown in Table 2.

[0099] Table 2 Carbonation results of hollow fiber-mediated bioconcrete with different fiber carriers

[0100]

[0101] Analysis of the carbonation degree test results showed that under carbonation curing conditions, the carbonation degree of the hollow fiber-mediated bioconcrete prepared with different fiber carriers was improved to different degrees compared with the control group at different ages. When cured for 28 d, the carbonation degree of the sisal fiber-loaded bacteria and PP fiber-loaded bacteria was increased by 26.62% and 33.33%, respectively, compared with the control group.

[0102] Analysis of the mechanical property test results showed that under carbonation curing conditions, the compressive strength of the hollow fiber-mediated bioconcrete prepared with different fiber carriers was improved to different degrees compared with the control group at different ages. When cured for 28 d, the compressive strength of the sisal fiber-loaded bacteria and PP fiber-loaded bacteria was increased by 25.88% and 30.21%, respectively, compared with the control group, and the flexural strength was increased by 12.83% and 17.69%, respectively.

[0103] The microstructure of the concrete was analyzed. The XRD results showed that the main components in the control group without the addition of BM were Ca(OH)2, and a small amount of CaCO3 was formed. In the S-B and P-B groups, Ca(OH)2 was almost completely converted into CaCO3, and the CaCO3 diffraction peak in the P-B group was the highest among all groups. The study also showed that the carbonation of the control group without the addition of bacteria and fibers was 17.37% at 600-800°C, corresponding to the decomposition of calcium carbonate. The carbonation of the S-B and P-B groups was 23.31% and 24.48%, respectively, which was 5.94% and 7.11% higher than that of the control group, respectively. The carbonic anhydrase secreted by Bacillus mucilaginosus accelerates the dissolution of CO2 and promotes the early precipitation of CaCO3 (MICP). The CaCO3 precipitation fills the microcracks and capillary pores, improving the density and mechanical properties. At the same time, the hollow fibers provide a relatively stable living and acting space for the BM. The lumen of the hollow fiber provides CO2 for the MICP produced by the BM, and its unique pore structure can guide sufficient CO2 to diffuse to the microbial enrichment area, thereby optimizing the spatial distribution of the carbonation reaction. The hollow fiber and the enzyme work together to synergistically promote carbonation.

[0104] Comparative Example 2

[0105] This comparative example investigates the effects of adding different concentrations of bacterial solution alone on the carbonation of carbonation-cured sea sand concrete, mechanical properties, and microstructure. The concentrations of the concentrated bacterial solution of the carbon-fixing microorganism were 2×10 3 CFU / ml, 2×10 6 CFU / ml, and 2×10 9 CFU / ml, which were added to the concrete matrix at a concentration of 10% of water. The specific proportions are shown in Table 3, and the remaining parameters are consistent with those in Comparative Example 1.

[0106] Table 3 Proportions of sea sand concrete prepared with different concentrations of bacterial solution

[0107]

[0108] The macroscopic properties of the sea sand concrete prepared with the above different proportions were tested, and the results are shown in Table 4, the carbonation degree variation is shown in Figure 4 , the mechanical property variation is shown in Figure 5 (b) and Figure 6 , and the microstructure is shown in Figure 7 (b) and 8(b).

[0109] Table 4 Carbonation degree results of sea sand concrete with different bacterial concentrations

[0110]

[0111] From Table 4, the carbonation degree of sea sand concrete with different bacterial concentrations can be known. Under carbonation curing conditions, the carbonation degree of concrete mixed with bacteria at different ages is improved to different degrees compared with the control group. When the carbonation curing time is 28d, the carbonation degree of the group with a bacterial concentration of 2x10 6 CFU / ml is the largest, which is 30.0% higher than that of the control group.

[0112] From the test results of the mechanical properties of sea sand concrete with different bacterial concentrations, it can be found that under carbonation curing conditions, the mechanical properties of carbonated sea sand concrete with three different bacterial concentrations first increase and then decrease; and the compressive strength and flexural strength reach the maximum value when the bacterial concentration is 2x10 6 CFU / ml. When the carbonation curing time is 28d, the compressive strength and flexural strength of the B2 group can be increased by 19.96% and 8.85% respectively compared with the C group.

[0113] From the XRD pattern, it can be found that the diffraction peak intensity of CaCO3 in the carbonated concrete sample mixed with BM is significantly improved, and the diffraction peak intensity of Ca(OH)2 is weakened, indicating that the minerals gradually carbonate with the addition of BM. The diffraction peak of Ca(OH)2 in the B2 group is the weakest, indicating that the carbonation efficiency is the highest at this concentration. The carbonic anhydrase (CA) produced by BM catalyzes the generation of a large amount of carbonate ions, as shown in formula (1) and (2). Ca(OH)2 reacts with carbonate to completely convert to CaCO3, so the CaCO3 peak value of the carbonation specimen mixed with bacteria is much higher than that of the control group concrete. At the same time, from the thermogravimetric results, it can be found that the carbon sequestration rates of B1, B2 and B3 with different bacterial concentrations are 19.4%, 21.9% and 20.4% respectively, which are increased by 2.1%, 4.6% and 3.1% respectively compared with the control group. With the increase of BM concentration, the concentrations of Ca 2+ , and H + in the environment increase. High concentration of bacteria can regulate the growth characteristics of nucleation sites and promote the precipitation process of carbonate by increasing the concentration of catalytic enzyme. Excessive aggregation of bacteria will lead to rapid depletion of nutrients such as urea and Ca 2+ , which will cause the metabolism to stop in the later stage. At the same time, the local supersaturation state will cause the disordered crystallization of CaCO3, which will weaken the bonding force between the interfaces, and thus the compressive strength will be reduced.

[0114] (1)

[0115] (2)

[0116] Comparative Example 3:

[0117] The present embodiment explores the influence of different volume contents of sisal fibers on the carbonation, mechanical properties and microstructure of carbonation-cured sea sand concrete.

[0118] In the present comparative example, the raw material composition does not contain the PP fibers and the bacterial solution described in Comparative Example 1, and the content of the sisal fiber used is 0.5 kg / m 3 , 1.0 kg / m 3 , 1.5 kg / m 3 , and the remaining parameters are consistent with those in Comparative Example 1.

[0119] The mix proportion of the present example is shown in Table 5, the macroscopic performance test results are shown in Table 6, the microstructure of the sisal fiber after modification is shown in Figure 3 , the carbonation degree variation is shown in Figure 4 , the mechanical property variation is shown in Figure 5 (c) and Figure 6 , and the microstructure is shown in Figure 7 (c) and 8(c).

[0120] Table 5 Mix proportion table of sea sand concrete with different sisal fiber contents

[0121]

[0122] Table 6 Carbonation results table of sea sand concrete with different sisal fiber contents

[0123]

[0124] By analyzing the carbonation degree test results of sea sand concrete with different sisal fiber contents, it can be found that under carbonation curing conditions, the carbonation degree of the concrete mixed with sisal fiber is higher than that of the control group at different ages. When carbonation curing for 28 days, the carbonation degree of the sisal fiber content of 1.0 kg / m 3 is the largest, which is 33.33% higher than that of the control group.

[0125] By analyzing the mechanical property test results of sea sand concrete with different sisal fiber contents, it can be found that under carbonation curing conditions, the mechanical properties of carbonation-cured sea sand concrete with three fiber contents first increase and then decrease; the compressive strength and flexural strength of the sisal fiber content of 1.0 kg / m 3 reach the maximum value. When carbonation curing for 28 days, the compressive strength and flexural strength of the S2 group can be increased by 16.35% and 9.96% respectively compared with the C group. The decline in 28d mechanical properties may be due to the decomposition of natural fibers at 28d, which leads to the increase of concrete pore structure.

[0126] Analysis of the microstructure test results of sea sand concrete with different sisal fiber content revealed that, according to XRD patterns, the diffraction peak intensity of CaCO3 in the carbonized concrete samples incorporating sisal fiber was significantly enhanced, while the diffraction peak intensity of Ca(OH)2 was weakened. Figure 2 The microstructure revealed that the sisal fibers, after alkali modification, had cavities distributed on their surface. These cavities provide permeation channels for CO2 during carbonation curing, allowing CO2 to enter the concrete and thus promoting higher carbonation levels. The strongest diffraction peak for CaCO3 was observed in group S2, indicating a fiber content of 1.0 kg / m³. 3 The carbonization efficiency was highest at this time. Meanwhile, according to the thermogravimetric results, the carbon fixation rates of the samples with different dosages of S1, S2, and S3 were 19.12%, 21.4%, and 20.5%, respectively, which were 1.8%, 4.1%, and 3.2% higher than those of the control group.

[0127] Comparative Example 4:

[0128] This comparative example analyzes the effects of different PP fiber dosages on the carbonation performance, mechanical properties, and microstructure of sea sand concrete. Unlike Comparative Example 1, this example does not contain sisal fiber or the carbon-fixing bacterial solution used in Comparative Example 1; the remaining parameters are consistent with those in Example 1. A dosage of 0.5 kg / m³ was used. 3 1.0 kg / m 3 1.5 kg / m 3 This study investigated the effect of different dosages of PP fiber on the carbonation of carbon-cured sea sand concrete. The proportions of each component in this comparative example are shown in Table 7, with dosages of 0.5 kg / m³. 3 1.0 kg / m 3 1.5 kg / m 3 The macroscopic performance test results of PP fiber in sea sand concrete are shown in Table 8. The microstructure of PP fiber after modification is shown in Table 8. Figure 3 As shown, the variation pattern of carbonization degree is as follows: Figure 4 As shown, the variation law of mechanical properties is as follows: Figure 5 (d) and Figure 6 As shown, the microscopic properties are as follows Figure 7 As shown in (d) and 8(d).

[0129] Table 7. Mix Proportions for Sea Sand Concrete with Different PP Fiber Contents

[0130]

[0131] Table 8 Carbonation Results of Sea Sand Concrete with Different PP Fiber Contents

[0132]

[0133] The carbonation degree test results of different PP fiber content sea sand concrete show that, under carbonation curing conditions, the carbonation degree of concrete mixed with PP fiber is higher than that of the control group at different ages. Similar to sisal fiber, the carbonation degree of PP fiber content of 1.0 kg / m 3 The carbonation degree of 1.0 kg / m

[0134] The mechanical property test results of different PP fiber content sea sand concrete show that, under carbonation curing conditions, the mechanical properties of carbonation cured sea sand concrete first increase and then decrease with different fiber contents; the compressive strength and flexural strength of sisal fiber content of 1.0 kg / m 3 The compressive strength and flexural strength of P2 group are increased by 17.50% and 10.40% respectively compared with C group at 28d. The decline in mechanical properties at 28d may be due to the uneven mixing of too much fiber, which forms clusters, and the fiber cluster area becomes a stress concentration point, causing cracks to preferentially expand.

[0135] The microstructure test results of different sisal fiber content sea sand concrete show that, from the XRD pattern, the diffraction peak intensity of CaCO3 in the carbonation concrete sample mixed with sisal fiber is significantly improved, and the diffraction peak intensity of Ca(OH)2 is weakened, which is similar to the result of sisal fiber. Figure 2 The microstructure can be found that the lumen pore size of the PP fiber surface after modification increases, which promotes the transmission of CO2 during carbonation curing, thereby promoting the improvement of carbonation degree. The diffraction peak of CaCO3 in P2 group is the strongest, indicating that the carbonation efficiency is the highest when the fiber content is 1.0 kg / m 3 At the same time, according to the thermogravimetric results, the carbon sequestration rates of P1, P2 and P3 with different contents are 19.63%, 21.58% and 20.53% respectively, which are increased by 2.26%, 4.21% and 3.16% respectively compared with the control group.

[0136] The above shows and describes the basic principles, main features and advantages of the present application. Those skilled in the art should understand that the present application is not limited to the above examples, and the above examples and descriptions in the specification are only to illustrate the principles of the present application. Without departing from the spirit and scope of the present application, various changes and improvements can be made to the present application, and these changes and improvements all fall within the scope of the claimed present application. The scope of protection of the present application is defined by the appended claims and their equivalents.

Claims

1. Hollow fiber-mediated bio-concrete-based carbon fiber, characterized in that, include: Fiber carriers that provide transport pathways and diffusion channels for CO2, and carbon-fixing microorganisms loaded on the fiber carriers; The fiber carrier has a hollow structure, providing a diffusion channel for CO2. The fiber carrier itself serves as a CO2 transport path, providing a living environment for carbon-fixing microorganisms, thereby overcoming the physical limitations on CO2 transport to the interior. Carbon-fixing microorganisms accelerate CO2 hydration to generate carbonate ions on the one hand, and secrete organic acids to dissolve the calcium in steel slag on the other. 2+ / Mg 2+ This forms carbonate precipitates, thereby achieving directional mineralization at the fiber-matrix interface and strengthening interfacial adhesion. The carbon-fixing microorganism is Bacillus mucilaginosus.

2. The hollow fiber-mediated bio-concrete-fixed carbon fiber according to claim 1, characterized in that, The fiber carrier is a natural hollow fiber and / or a synthetic hollow fiber.

3. A method for preparing hollow fiber-mediated bio-concrete-fixed carbon fibers, characterized in that, The preparation method is applied to the preparation of hollow fiber-mediated bio-concrete solidified carbon fibers as described in any one of claims 1-2, and the preparation method includes: S1, hollow fiber filaments are prepared using natural hollow fibers and / or synthetic hollow fibers; S2, pretreatment of hollow fiber filaments, followed by alkali modification, impurity removal, and drying of the pretreated hollow fiber filaments to obtain a fiber carrier, wherein the fiber carrier can improve the antistatic and flame retardant properties of the hollow fiber filaments while maintaining the original mechanical properties of the hollow fiber filaments. S3, the fiber carrier is surface treated to increase its roughness; S4, the fiber carrier was immersed in a carbon-fixing microbial culture medium to obtain hollow fiber-mediated bio-concrete carbon fiber; wherein the fiber volume content of the fiber carrier was 0.5 kg / m³. 3 ~1.5 kg / m 3 ; The concentration of the carbon-fixing microbial culture medium is 2×10⁻⁶. 3 CFU / m~2×10 9 CFU / ml, soaked at constant temperature for 12 hours.

4. The method for preparing hollow fiber-mediated bio-concrete-fixed carbon fiber according to claim 3, characterized in that, The alkali modification treatment in S2 involves soaking in an organic amine solution at room temperature for 12 hours. The organic amine solution is an ethanolamine solution.

5. The method for preparing hollow fiber-mediated bio-concrete-fixed carbon fiber according to claim 3, characterized in that, The pretreatment process of hollow fiber filaments in S2 includes soaking in an alkaline solution followed by rinsing with clean water; the impurity removal process in S2 involves rinsing with an alcohol solution followed by repeated rinsing with clean water.

6. The method for preparing hollow fiber-mediated bio-concrete-fixed carbon fiber according to claim 5, characterized in that, The alkaline solution is an 80% sodium hydroxide solution, soaked at 80°C for 24 hours; The alcohol solution is a 50% anhydrous ethanol solution.

7. A hollow fiber-mediated bio-concrete, characterized in that, The bio-concrete comprises: a concrete matrix and reinforcing fibers embedded in the concrete matrix; The reinforcing fiber is the hollow fiber-mediated bio-concrete solid carbon fiber as described in any one of claims 1 to 2; The hollow fiber-mediated bio-concrete carbon fiber provides a transport path and diffusion channel for CO2 in the concrete matrix and a living environment for the loaded carbon-fixing microorganisms through its hollow structure. On the other hand, the loaded carbon-fixing microorganisms perform directional mineralization at the interface between the reinforcing fiber and the concrete, thereby increasing the carbon fixation capacity of the concrete and strengthening the interface. The generated carbonate precipitates not only increase the carbon fixation capacity of the concrete but also tightly fill and strengthen the interface transition zone, thus improving the carbon fixation efficiency and mechanical properties of the concrete.

8. The hollow fiber-mediated bioconcrete according to claim 7, characterized in that, The concrete matrix is ​​composed of steel slag, cementitious materials, sand and gravel aggregates, and water.

9. The hollow fiber-mediated bio-concrete according to claim 7, characterized in that, The carbonization and carbon sequestration method for the bio-concrete includes: S1, Preparation of concrete matrix materials; S2, hollow fiber-mediated bio-concrete solid carbon fiber is added to the concrete matrix material, stirred to make it evenly dispersed in the concrete matrix material, and then poured into the corresponding model for curing. S3, the cured bio-concrete was placed in carbonization curing chambers with 50% CO2, 50% RH and 25℃ respectively for 7d, 14d and 28d.

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