A full-solid-waste-based bio-fiber coordinated microbial mineralization flow-state solidified soil and a preparation method thereof

Abstract

The application discloses a kind of full solid waste base biological fiber cooperates microorganism mineralization flow state solidified soil and preparation method thereof.The application is immersed in alkaline solution by biological base fiber, and modified carrier material is obtained;Waste concrete or waste brick ball is crushed and ball milled, and recycled micro-powder cementitious material is prepared;Modified carrier material is mixed with engineering waste, and recycled micro-powder cementitious material is dry mixed, and urease-producing bacterial solution or calcium carbonate precipitation-inducing microbial solution is added to stirring and standing, and mixture is obtained;Urea and calcium source are contained in the mixture and added to cementing fluid, and stirring is obtained, and the full solid waste base biological fiber flow state solidified soil is obtained.The application utilizes the alkaline excitation of recycled micro-powder, the carrier anchoring of biological fiber and the suspension synergistic effect of biological glue, effectively solves the problems of traditional MICP flow state soil bacteria easy loss, cement-free system easy segregation and large brittleness, and the prepared filler has the characteristics of high flowability, high toughness and low carbon environmental protection.

Description

Technical Field

[0001] This invention relates to the field of geotechnical engineering materials and solid waste resource utilization technology, specifically to a solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil and its preparation method. Background Technology

[0002] With the acceleration of urbanization, the excavation of foundation pits, tunneling, and building demolition have generated massive amounts of construction waste and waste concrete. Traditional disposal methods mostly involve landfilling, which can easily lead to environmental geological disasters such as landslides and dust storms. On the other hand, traditional compacted soil cannot be implemented in narrow spaces such as backfilling trenches and filling abandoned pipe corridors. While conventional cement-based fluidized solidified soil has good fluidity, cement production is energy-intensive and has high carbon emissions. Furthermore, excessive use of cement leads to brittleness and cracking of the solidified soil after hardening, which does not meet the requirements of the current "dual-carbon" strategy.

[0003] Microbial induced calcium carbonate precipitation (MICP) is an environmentally friendly reinforcement technology that utilizes urease-producing bacteria to hydrolyze urea to generate calcium carbonate cemented soil particles. However, when combining traditional MICP technology with fiber reinforcement for fluidized bed construction, three major technical bottlenecks remain: 1. Poor biocompatibility of synthetic fibers: Current technologies mostly use synthetic fibers such as polypropylene (PP) as reinforcing materials. Due to their smooth and hydrophobic surface, microorganisms have difficulty attaching and colonizing on their surface, resulting in weak interfacial bonding between the fibers and calcium carbonate crystals. This makes it difficult to form an effective "biological-fiber-mineral" synergistic reinforcement system, and the fibers are also prone to floating or segregating in fluid slurries due to density differences.

[0004] 2. Bacterial Loss and Activity Inhibition under High Water-to-Solid Ratios: Fluidized solidified soils typically require a high water-to-solid ratio (>0.6). In the absence of an effective carrier, bacteria are easily lost with the free water, leading to low bonding efficiency. Furthermore, existing technologies often rely on cement or chemical reagents (such as sodium hydroxide) to adjust the pH value, and highly alkaline environments and heat of hydration easily inhibit microbial activity.

[0005] 3. Uneven reaction and "flash coagulation": If the bacterial solution, calcium source cementitious solution and soil are mixed at one time, the local high concentration of calcium ions will instantly encapsulate the undispersed bacteria to form precipitation, resulting in "flash coagulation" or local caking, blocking the seepage channels, hindering deep solidification, and making it difficult to maintain the suspension stability of solid particles in a cement-free system.

[0006] Therefore, there is an urgent need to develop a method for preparing fluidized solidified soil that utilizes natural fiber carriers with high biocompatibility and combines recycled micro powder from construction solid waste to replace cement, thereby achieving a method that produces all-solid-waste, low-carbon, and high-strength and tough soil. Summary of the Invention

[0007] To address the technical problems of existing fluidized bed solidification technologies, such as heavy reliance on high-energy-consuming cement, poor biocompatibility of traditional synthetic fibers (e.g., polypropylene) leading to high microbial loss rates, and the brittleness and cracking of MIP-solidified soil, this invention provides a fully solid waste-based bio-fiber synergistic microbial mineralization fluidized bed solidification soil and its preparation method. This method completely eliminates silicate cement, utilizes recycled micropowder from construction waste to stimulate microbial activity, and uses modified bio-based fibers as a "colonization carrier" for microorganisms, achieving fluidization, high strength and toughness, and full solid waste resource utilization of engineering waste soil.

[0008] The primary objective of this invention is to provide a method for preparing a fully solid waste-based bio-cellulose fluidized solidified soil, comprising the following steps: Bio-based fibers were immersed in an alkaline solution for surface roughening treatment to obtain a modified carrier material; Waste concrete or waste brick slag is crushed and ball-milled to produce recycled micro powder cementitious material; The modified carrier material is dry-mixed with engineering waste soil and the recycled micro powder cementitious material. Then, urease-producing bacterial solution or microbial solution that induces calcium carbonate precipitation is added, stirred and allowed to stand, so that the bacteria are adsorbed on the surface of the carrier material and the recycled micro powder cementitious material to obtain a mixture. Add a cementing solution containing urea and calcium source to the mixture and stir to obtain the all-solid waste-based bio-fiber fluidized solidified soil.

[0009] In some embodiments of the present invention, the bio-based fiber includes sisal fiber or loofah sponge.

[0010] In some embodiments of the present invention, the alkaline solution includes one or more of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, sodium carbonate solution, and sodium silicate solution; the present invention removes lignin impurities from the fiber surface through alkaline treatment to improve the adsorption capacity for bacteria; The concentration of the alkaline solution is 2wt% to 4wt%. Soaking time is 1 to 2 hours.

[0011] In some embodiments of the present invention, the resulting recycled micro-powder cementitious material has a particle size of less than 0.075 mm and a specific surface area of ​​≥400 m². 2 / kg. This invention utilizes regenerated micro-powder to provide an alkaline environment of pH 8.5–9.5 in the slurry, replacing chemical alkali regulators to maintain urease activity.

[0012] In some embodiments of the present invention, the mass ratio of the modified carrier material to the engineering waste soil and the recycled micro-powder cementitious material is (2-4):1000:(150-300); The construction waste soil is low liquid limit clay, with a liquid limit of 20% to 50% and a plastic limit of 10% to 25%.

[0013] In some embodiments of the present invention, the urease activity of the urease-producing bacterial culture is not less than 10 mM urea / min, and the OD600 value is 1.2 to 1.8. The bacteria in the urease-producing bacterial solution include one or more of Bacillus pasteurellii, Bacillus megaterium, Bacillus spheroidae, Bacillus subtilis, Bacillus caudatus, and Arthrobacter. Microorganisms that induce calcium carbonate precipitation include Bacillus mucilaginosus and / or Pseudomonas denitrificans; Let it stand for 2 to 5 minutes.

[0014] In some embodiments of the present invention, the cementing solution includes bone glue or xanthan gum; the concentration of the bone glue or xanthan gum is 0.05wt% to 0.1wt%; the use of bone glue or xanthan gum is to improve the suspension stability of the slurry; The concentration of urea in the cementing solution is 0.1 mol / L to 2.0 mol / L; The concentration of calcium ions in the cementing solution is 0.1 mol / L to 2.0 mol / L.

[0015] Furthermore, it is preferable that the molar concentration ratio of urea to calcium ions is 1:1; Preferably, the concentration range of urea and calcium ions is 0.5 mol / L to 1.5 mol / L.

[0016] In some embodiments of the present invention, the fluidity of the slurry is 160 mm to 220 mm.

[0017] In this invention, the cementing solution is added after the bacterial solution, and the calcium source in the cementing solution is provided by the acid hydrolysis leachate of construction waste.

[0018] The second objective of this invention is to provide a fully solid waste-based bio-fiber fluidized solidified soil, prepared by the aforementioned method. The microstructure of the fully solid waste-based bio-fiber fluidized solidified soil exhibits an interfacial directional cementation characteristic of "fiber-calcium carbonate-soil particles". Calcite-type calcium carbonate crystals are densely wrapped around the surface of the alkali-treated bio-based fibers and at the contact points between the fibers and soil particles, forming a bio-reinforced network with micro-anchoring effect.

[0019] In some embodiments of the present invention, the 28-day unconfined compressive strength of the all-solid waste-based bio-fiber fluidized solidified soil is not less than 1.5 MPa.

[0020] The synergistic solidification system of "self-regulating alkalinity of recycled building powder-targeted mineralization of bio-fiber carrier" constructed in this invention specifically includes the following key steps: Step 1: Solid waste matrix activation and fiber modification. Construction waste concrete or brick slag is ball-milled to a specific surface area of ​​not less than 400 m². 2 / kg of recycled micro powder was used as an auxiliary cementing material and alkaline activator; sisal fiber or loofah sponge was selected and subjected to surface roughening and lignin removal treatment by soaking in dilute alkali solution to obtain modified bio-based fiber with high biocompatibility.

[0021] Step Two: Microbial Targeted Adsorption and Carrier Construction. The engineering waste soil, recycled micro-powder, and modified bio-based fibers are dry-mixed, followed by the addition of urease-producing microbial inoculum and some of the mixing water. The mixture is stirred at low speed and allowed to stand for 2–5 minutes. Mechanism Explanation: This step utilizes the microscopic rough structure and hydrophilic groups on the surface of the modified fibers, combined with the electrostatic attraction during the standing period, to allow microorganisms to preferentially adsorb and colonize on the fiber surface and in the pores of the micro-powder, constructing an active reinforced "fiber-bacteria" network to prevent bacteria from being lost with free water during subsequent water addition.

[0022] Step 3: Delayed Activation and Fluidized Bed Molding. Add a binder containing urea, calcium source, and biorheology modifier (bone glue or xanthan gum) to the mixture from Step 2, and stir at high speed until the slurry fluidity reaches 160mm–220mm. Mechanism Explanation: The delayed addition of the binder avoids the inhibition of unadsorbed bacterial activity by high concentrations of calcium ions; the calcium hydroxide released from the hydration of recycled building powder creates a weakly alkaline environment of pH 8.5–9.5 in situ within the slurry, stimulating the microorganisms on the fiber surface to undergo mineralization reactions.

[0023] This invention completely abandons silicate cement and uses recycled micro powder from mechanically ball-milled construction waste as an alkaline activating material. It utilizes the hydration characteristics to construct a weakly alkaline environment of pH 8.5-9.5 required for the MIP reaction in situ. Sisal or loofah fibers modified by soaking in dilute sodium hydroxide solution are selected as reinforcing materials and microbial carriers. The process adopts a "pre-adsorption-delayed activation" sequential mixing strategy. First, the urease-producing bacterial solution is mixed with the solid matrix and allowed to stand for 2-5 minutes to allow the microorganisms to target and colonize the rough surface of the fiber. Then, a cementing solution containing a biorheology modifier (bone glue or xanthan gum) is added and stirred until fluidized.

[0024] The beneficial effects of this invention are: 1. Breakthrough in the technical bottleneck of "cement-free" curing: This invention does not use silicate cement at all, but innovatively utilizes the hydration characteristics of recycled building powder (finely ground waste concrete / brick slag), which not only provides the alkaline environment necessary for the MIP reaction (replacing chemical alkali), but also synergistically fills the pores with mineralized products (replacing cement bonding), thus achieving true "waste treatment with waste" and low-carbon environmental protection.

[0025] 2. Solved the problem of microbial "loss" in fluidized soil: Unlike traditional smooth and hydrophobic polypropylene fibers, this invention uses alkali-treated bio-based fibers (sisal / loofah). Their natural porous and rough surface provides an ideal carrier for microorganisms. Combined with a sequential mixing process of "adsorption followed by activation," the retention rate and mineralization efficiency of bacteria are significantly improved, resulting in calcium carbonate crystals mainly deposited on the fiber surface, enhancing the interfacial bonding between the fiber and the soil matrix.

[0026] 3. A balance between high fluidity and anti-segregation: To address the problem of easy segregation in cement-free slurry, a biological rheology modifier (bone glue / xanthan gum) was introduced to jointly construct a liquid-phase viscous network with biological fibers. This ensures that while the slurry meets the pumping fluidity requirement (≥160mm), the coarse aggregate does not settle or bleed water, and the hardened soil exhibits excellent toughness and ductile failure characteristics. Attached Figure Description

[0027] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein... Figure 1 This is a construction process flow chart of the all-solid waste-based bio-fiber fluidized solidified soil according to an embodiment of the present invention, which shows the steps of "solid waste recycling - fiber modification - sequential mixing - pumping curing"; Figure 2 This is a schematic diagram of the integrated production device for fluidized solidified soil used in an embodiment of the present invention, showing the connection relationship between the recycled micro powder silo, the fiber modification tank and the dual-liquid diversion mixing system; Figure 3 This is a comparison chart of the flowability and mechanical properties test results of various embodiments and comparative examples of the present invention. The stacked bar chart shows the influence of different fiber types and mixing processes on strength and breaking strain. Detailed Implementation

[0028] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0029] I. Experimental Materials and Preparation In the embodiments of the present invention, unless otherwise stated, all chemical reagents used are commercially available analytical grade, and the water is deionized water.

[0030] 1. Construction waste soil: Waste soil taken from a construction foundation pit project, after being air-dried, crushed and passed through a 2mm standard sieve, was found to have a liquid limit of 34.5% and a plastic limit of 18.2%, which is classified as low liquid limit clay.

[0031] 2. Recycled building powder (cement substitute): Taken from waste concrete blocks generated during building demolition, crushed by a jaw crusher and ground by a ball mill, then passed through a 200-mesh sieve (particle size <0.075mm), with a specific surface area ≥400m². 2 / kg. Its main components are calcium carbonate and unhydrated calcium silicate particles, used to provide the alkaline environment required for the MIP reaction and as a micro-aggregate filler.

[0032] 3. Bio-based fiber (carrier material): Natural sisal fiber (or loofah sponge) from Guangxi is selected. Before use, it is soaked in 2%–4% NaOH solution for 1–2 hours, then rinsed with clean water and dried, and cut to lengths of 6 mm, 9 mm, and 12 mm. The pretreatment aims to remove surface lignin and pectin, exposing the rough surface of the cellulose to facilitate microbial attachment.

[0033] 4. Microbial strains: Sporosarcina pasteurii (ATCC11859) was used, purchased from the Shanghai Culture Collection Center. After expansion, the OD600 value of the bacterial culture was controlled at 1.2–1.8, and the urease activity was not less than 10 mM urea / min.

[0034] 5. Bio-rheology modifier: Industrial-grade bone glue (or xanthan gum) is selected as a thickening component of the binder to improve the suspension stability of cementless slurry. II. Specific Implementation Methods Example 1: This embodiment prepares a high-strength, tough, fluidized solidified soil that completely eliminates the need for cement and utilizes recycled building powder to activate its activity. The specific steps are as follows: Step 1: Preparation of delayed-acting cementitious solution: Weigh urea and anhydrous calcium chloride, dissolve them in water to prepare an equimolar mixed solution with a concentration of 1.0 mol / L; add bone glue solution with a mass fraction of 0.1% and stir evenly to obtain a cementitious solution containing biorheology modifier.

[0036] Step 2: Dry material premixing: Weigh 1000g of pretreated dry slag, 200g of recycled building powder and 3g of modified sisal fiber (0.3% of the dry soil mass) and put them into a mixer. Mix at medium speed for 60s to ensure that the fiber and powder are evenly dispersed in the soil matrix.

[0037] Step 3 Targeted Adsorption and Colonization: Spray 300mL of urease-producing bacteria solution and 182mL of mixing water into the mixture, stir at low speed for 60s, and let stand for 3 minutes.

[0038] Processing Mechanism: By utilizing the settling period and the micro-rough structure of the modified fiber surface, negatively charged bacteria are directionally adsorbed and fixed on the fiber surface and in the micro-powder pores under the action of electrostatic attraction, forming "fiber-bacteria" active aggregates, preventing bacteria from being lost with free water during subsequent water addition.

[0039] Step 4: Activation and molding: Add 300 mL of the bone glue-containing binder prepared in Step 1 to the mixture after it has been allowed to stand, adjust the total water-to-solid ratio to 0.65, and stir at high speed for 120 s until the slurry reaches fluidization (flowability 160-220 mm).

[0040] Processing Mechanism: OH- released during the hydration of recycled building powder - Ions in situ created a weakly alkaline environment with a pH of 8.5–9.5 in the slurry, stimulating the activity of microorganisms adsorbed on the fiber surface; bone glue increased the viscosity of the slurry, preventing the segregation of solid waste particles.

[0041] Step 5 Curing: Pour the slurry into a 70.7mm×70.7mm×70.7mm triple mold, do not vibrate (utilizing its self-compacting properties), and cure at room temperature in a sealed environment for 24 hours. Then remove the mold and continue standard curing for 28 days to obtain a fully bio-based fiber synergistic microbial mineralization solidification recycled construction waste fluid filler.

[0042] Example 2 This embodiment provides a fully solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil and its preparation method. The only difference from Embodiment 1 is the change in the feeding ratio of the core raw materials, specifically: The mass ratio of the modified carrier material, the engineering waste soil and the recycled micro powder cementitious material is 2:1000:150 (that is, 1000g of engineering waste soil, 150g of recycled micro powder and 2g of modified sisal fiber are weighed and mixed).

[0043] All other raw material parameters, cementing solution concentration, and preparation steps and process conditions are completely consistent with those in Example 1 (the amount of mixing water is calculated and adjusted proportionally according to the total mass of the adjusted solids and the total water-to-solid ratio of 0.65).

[0044] Example 3 This embodiment provides a fully solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil and its preparation method. The only difference from Embodiment 1 is that the feeding ratio of the core raw materials is changed, taking the upper limit of the scope of protection of the claims. Specifically: The mass ratio of the modified carrier material, the engineering waste soil and the recycled micro powder cementitious material is 4:1000:300 (that is, 1000g of engineering waste soil, 300g of recycled micro powder and 4g of modified sisal fiber are weighed and mixed).

[0045] All other raw material parameters, cementing solution concentration, and preparation steps and process conditions are completely consistent with those in Example 1 (the amount of mixing water is calculated and adjusted proportionally according to the total mass of the adjusted solids and the total water-to-solid ratio of 0.65).

[0046] Comparative Example 1 (Verifying the effect of unmodified fibers): This comparative example provides a method for preparing a fully bio-based fiber-assisted microbial mineralization and solidification regenerated construction waste fluidized bed packing. The only difference from Example 1 is that virgin sisal fiber is used instead of modified sisal fiber. The remaining raw material ratios (regenerated micro powder, bone glue, bacterial solution concentration) and preparation process (stepwise sequential mixing) are completely consistent with Example 1.

[0047] Comparative Example 2 (to verify the toughening effect of the fibers, without the addition of modified fibers): This comparative example provides a method for preparing a fully bio-based fiber-assisted microbial mineralization and solidification method for recycled construction waste fluidized bed filler. The only difference from Example 1 is that no fiber is added; only MIP and recycled micropowder are used to solidify the slag. The remaining raw material ratios and preparation process are completely consistent with Example 1.

[0048] Comparative Example 3 (Verification of sequential mixing process): This comparative example provides a control group prepared by a one-time mixing method, which differs from Example 1 only in that it uses a one-time feeding and mixing process.

[0049] Specific operation: Put the slag, recycled building powder, modified sisal fiber, bacterial solution, cementing liquid (containing bone glue) and water into the mixer at one time, and stir continuously at the same speed for 5 minutes without letting it stand in between.

[0050] Comparative Example 4 (Verifying the feasibility of total solid waste substitution): This comparative example provides a cement-based control group, which differs from Example 1 only in that: PO 42.5 ordinary Portland cement is used as a substitute for recycled building powder by mass, and no bone glue is added to the binder (cement paste has inherent anti-segregation properties). Modified sisal fiber is still used.

[0051] III. Experimental Results and Analysis The fluidized solidified soil samples prepared in Example 1 and Comparative Examples 1-4 were subjected to initial flowability tests, 28-day unconfined compressive strength (UCS) tests, and failure morphology observations. The test results are shown in Table 1.

[0052] Table 1 Comparison of performance test results between the examples and the comparative examples. Results analysis: 1. Reinforcing Mechanism of Fiber Modification (Example 1 vs. Comparative Example 1): The compressive strength of Example 1 was increased by 24.4% compared to Comparative Example 1. Scanning electron microscopy (SEM) revealed that the modified sisal fibers in Example 1 had a large number of dense calcite crystals deposited on the surface and in the internal pores, forming a "biomineralized armor" that significantly increased the interfacial friction between the fiber and the soil matrix; while the original fibers in Comparative Example 1 had sparse crystal distribution on the surface and were easily pulled out under stress. This confirms the effectiveness of the "alkali treatment to construct microbial carrier" technical solution in the claims.

[0053] 2. Feasibility of Complete Solid Waste and Cement-Free Methods (Example 1 vs. Comparative Example 4): Example 1 utilizes recycled building powder to completely replace cement, achieving a 28-day strength of 1.68 MPa. While slightly lower than the cement-based group's 1.92 MPa, it fully meets the engineering application standards for fluidized solidified soil (typically requiring ≥1.0 MPa). Furthermore, thanks to the addition of bone glue, no segregation or bleeding occurred in the slurry of Example 1. This indicates that utilizing the alkalinity of recycled powder to activate MIP activity is an effective way to achieve "cement-free" solidification.

[0054] 3. The criticality of the sequential mixing process (Example 1 vs. Comparative Example 3): The strength of Example 1, which uses a step-by-step static settling process, is significantly higher than that of Comparative Example 3, which uses a one-time mixing process (1.05 MPa). Obvious white flocculent precipitates were observed on the cross-section of the sample in Comparative Example 3. This was due to the rapid precipitation (flash coagulation) of calcium carbonate in the liquid phase caused by direct contact between calcium ions and the bacterial solution, failing to effectively cement the contact points of soil particles. In contrast, Example 1, through "static adsorption," concentrates crystal growth sites mainly on the fiber and particle surfaces, forming an effective cementing network.

[0055] 4. Toughening and crack-preventing effect (Example 1 vs Comparative Example 2): Compared with the brittle disintegration failure of the fiber-free group (Comparative Example 2), Example 1, which incorporates modified bio-fibers, showed significant ductile failure characteristics, with a 2.5-fold increase in failure strain. The specimen could still maintain its overall shape after reaching the peak load, indicating that the bio-fibers played a key bridging and crack-preventing role inside the soil.

[0056] In summary, this invention, through a specific step-by-step mixing process and parameter control (water-to-solid ratio 0.60-0.70, fiber 0.2-0.4%), successfully solves the problems of high brittleness and difficult fluidized bed construction in traditional MIP-stabilized soil. Example data shows that the fluidized filler prepared by this invention not only meets the flowability requirements for pumping construction but also possesses excellent mechanical strength and deformation toughness, achieving a synergistic effect of 1+1>2 between "microbial chemical bonding" and "fiber physical reinforcement".

[0057] The embodiments described above are merely preferred embodiments for fully illustrating the present invention, and the scope of protection of the present invention is not limited thereto. Equivalent substitutions or modifications made by those skilled in the art based on the present invention are all within the scope of protection of the present invention.

Claims

1. A method for preparing a fully solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil, characterized in that, Includes the following steps: Bio-based fibers were immersed in an alkaline solution for surface roughening treatment to obtain a modified carrier material; Waste concrete or waste brick slag is crushed and ball-milled to produce recycled micro powder cementitious material; The modified carrier material is dry-mixed with engineering waste soil and the recycled micro powder cementitious material. Then, urease-producing bacterial solution or microbial solution that induces calcium carbonate precipitation is added, stirred and allowed to stand, so that the bacteria are adsorbed on the surface of the carrier material and the recycled micro powder cementitious material to obtain a mixture. Add a cementing solution containing urea and calcium source to the mixture and stir to obtain the all-solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil.

2. The preparation method according to claim 1, characterized in that, The bio-based fibers include sisal fibers or loofah fibers.

3. The preparation method according to claim 1, characterized in that, The alkaline solution includes one or more of sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, sodium carbonate solution, and sodium silicate solution; The concentration of the alkaline solution is 2wt% to 4wt%. Soaking time is 1 to 2 hours.

4. The preparation method according to claim 1, characterized in that, The resulting recycled micro-powder cementitious material has a particle size of less than 0.075 mm and a specific surface area of ​​≥400 m². 2 / kg.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the modified carrier material to the engineering waste soil and the recycled micro-powder cementitious material is (2~4):1000:(150~300). The construction waste soil is low liquid limit clay, with a liquid limit of 20% to 50% and a plastic limit of 10% to 25%.

6. The preparation method according to claim 1, characterized in that, The urease activity of the urease-producing bacterial culture is not less than 10 mM urea / min, and the OD600 value is 1.2 to 1.

8. The bacteria in the urease-producing bacterial solution include one or more of Bacillus pasteurellii, Bacillus megaterium, Bacillus spheroidae, Bacillus subtilis, Bacillus caudatus, and Arthrobacter. Microorganisms that induce calcium carbonate precipitation include Bacillus mucilaginosus and / or Pseudomonas denitrificans; Let it stand for 2 to 5 minutes.

7. The preparation method according to claim 1, characterized in that, The cementing solution comprises bone glue or xanthan gum; the concentration of the bone glue or xanthan gum is 0.05wt% to 0.1wt%. The urea content in the cementing solution is 0.1 mol / L to 2.0 mol / L; The calcium ion content in the cementing solution is 0.1 mol / L to 2.0 mol / L.

8. The preparation method according to claim 1, characterized in that, The fluidity of the slurry is 160 mm to 220 mm.

9. A fully solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil, characterized in that, The solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil is prepared by any one of the preparation methods described in claims 1 to 8. The microstructure of the solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil exhibits the interfacial directional cementation characteristics of "fiber-calcium carbonate-soil particles". The calcite-type calcium carbonate crystals are densely wrapped on the surface of the alkali-treated bio-based fiber and at the contact points between the fiber and the soil particles, forming a bio-reinforced network with micro-anchoring effect.

10. The all-solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil according to claim 9, characterized in that, The 28-day unconfined compressive strength of the solid waste-based bio-fiber synergistic microbial mineralization fluidized solidified soil is not less than 1.5 MPa.

Images