A highly robust cementitious material and method of making the same

Abstract

The application discloses a kind of high anti-disturbance cement-based materials and its preparation method, belong to cement-based material production technical field.It includes: preparation polyvinyl alcohol-sodium borate hydrogel, and freeze-drying processing and crushing processing, obtain granular material;By melt spinning processing fiber raw material obtains expanded fiber, to expanded fiber is carried out surface indentation processing, obtains indentation expanded fiber;By electrostatic adsorption granular material is adsorbed on indentation expanded fiber, obtains modified indentation expanded fiber;Bacillus is inoculated to spontaneous combustion coal gangue, obtains first aggregate, after first aggregate and quartz sand are mixed, second aggregate is prepared;After cementing material, second aggregate and modified indentation expanded fiber are mixed according to preset proportion, add water and stir uniformly, high anti-disturbance cement-based material is prepared.The high anti-disturbance cement-based material of the application has early strength and high toughness under dynamic disturbance condition, can effectively resist the damage caused by disturbance to material.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of cement-based material production, and particularly relates to a high-disturbance-resistant cement-based material and a preparation method thereof. BACKGROUND

[0002] In bridge construction and road bridge surface repair engineering, in order to reduce the influence on traffic, construction is usually carried out under the condition of open or semi-open traffic, so it is necessary to ensure that the cement-based material can maintain high interfacial bonding strength and structural integrity in complex dynamic loads (such as vehicle impact, temperature alternation and structure deformation transmission, etc.) and harsh environments (such as salt corrosion and freeze-thaw cycle, etc.).

[0003] Due to the insufficient adaptability of the dynamic disturbance (referring to the instantaneous or periodic disturbance of the cement-based material structure under dynamic external load, such as vehicle impact, which causes changes in internal stress, microstructure or mechanical properties) of the traditional cement-based material, microcracks are easily generated at the interface of the joint or repair layer under the action of repeated vehicle rolling and temperature expansion and contraction, and disturbance stress concentration also causes the cement-based material to peel off or penetrate and crack, thereby causing repair failure. Therefore, it is necessary to develop a high-disturbance-resistant cement-based material with self-repairing ability and high toughness under dynamic disturbance conditions. SUMMARY

[0004] To solve the above technical problems, the application provides a high-disturbance-resistant cement-based material and a preparation method thereof, which can effectively improve the disturbance resistance and bearing capacity of the cement-based material, and the self-repairing ability of the cement-based material.

[0005] To achieve the above purpose, the application provides a preparation method of a high-disturbance-resistant cement-based material, comprising the following steps:

[0006] Preparation of polyvinyl alcohol-sodium borate hydrogel, and freeze-drying treatment and crushing treatment to obtain particulate matter;

[0007] The fiber raw material is treated by melt spinning to obtain expanded fibers, and the fibers are subjected to surface indentation treatment to obtain indented expanded fibers;

[0008] The particulate matter is adsorbed on the indented expanded fibers by electrostatic adsorption to obtain modified indented expanded fibers;

[0009] The spores of Bacillus are inoculated into self-igniting coal gangue to obtain first aggregate, and the first aggregate is mixed with quartz sand to obtain second aggregate;

[0010] The cementitious material, the second aggregate and the modified indented expanded fibers are mixed according to a predetermined proportion, water is added and stirred uniformly to obtain a high-disturbance-resistant cement-based material.

[0011] Further, the polyvinyl alcohol-sodium borate hydrogel is prepared by the following method:

[0012] The 10wt% polyvinyl alcohol solution and the 5wt%-20wt% sodium borate solution are mixed in a mass ratio of (2-5):1 under stirring, and after the reaction is completed, the mixture is cooled to room temperature, and after the bubbles are removed, the polyvinyl alcohol-sodium borate hydrogel is prepared.

[0013] Further, the temperature of the freeze-drying treatment is-30°C to-50°C, and the time is 3h-6h; the particle size of the particulate matter is less than 500 mesh.

[0014] Further, the expanded fiber is obtained by melt spinning treatment of the fiber raw material, including:

[0015] 5-8 parts of the modified graphene particles, 10-15 parts of the temperature-sensitive polyurethane particles, and 15-18 parts of the polyvinyl alcohol particles are weighed and uniformly mixed to obtain a mixture.

[0016] The mixture is treated by melt spinning to obtain an expanded fiber; wherein,

[0017] The parameters of the melt spinning treatment include: an extrusion temperature of 250°C, a flow rate of 0.5m / min-0.8m / min, a circular spinneret hole size of 0.3mm, a spacing of 15mm, and a spinning length of 1m.

[0018] Further, the modified graphene particles are prepared by the following method:

[0019] The graphene oxide and deionized water are mixed in a ratio of 200mg:500mL, and then an ultrasonic water bath is used for dispersion to obtain a first mixture;

[0020] 2.0g of 4-styrene sulfonic acid sodium is added to the first mixture and stirred for more than 1h until the 4-styrene sulfonic acid sodium is completely dissolved to obtain a second mixture;

[0021] 10g of hydrazine hydrate is added to the second mixture, and heated at 95°C in a water bath for 24h to obtain a preliminary product;

[0022] The preliminary product is washed with deionized water and then dried for 24h to obtain the modified graphene particles.

[0023] Further, the temperature-sensitive polyurethane particles are prepared by the following method:

[0024] 60g of poly 1,2-propanediol and 35g of L-lysine ethyl ester diisocyanate are mixed and stirred at room temperature for more than 48h to obtain an initial product;

[0025] The initial product is dissolved in 200 mL of a methanol solution, and diethyl ether is added as a precipitant, the dissolution-precipitation process is repeated 3 times, and then the final precipitate is taken out and dried in an oven for 48 h to obtain temperature-sensitive polyurethane particles.

[0026] Further, the fiber length of the score expansion fiber is 15 mm to 20 mm, and the score depth of the score expansion fiber is 0.4 mm to 0.6 mm.

[0027] Further, the spores are inoculated into the self-igniting coal gangue to obtain first aggregates, including:

[0028] The self-igniting coal gangue is crushed to a particle size of less than 5 mm to obtain coal gangue particles;

[0029] The coal gangue particles and the spore nutrient solution are sterilized using high-temperature steam and cooled to room temperature;

[0030] The spores are inoculated into the cooled spore nutrient solution under sterile conditions at an inoculation amount of 1% for culture to obtain a bacterial solution with a concentration of (4-6) x 10 7 cfu / mL;

[0031] The cooled coal gangue particles are added to the bacterial solution for vacuum soaking treatment and drying treatment, and the first aggregates are obtained after constant weight; wherein the pressure of the vacuum soaking treatment is -0.07 MPa to -0.03 MPa, and the time of the vacuum soaking treatment is 25 min to 40 min; the temperature of the drying treatment is 38°C to 45°C.

[0032] Further, the mass ratio of the first aggregates to quartz sand in the second aggregates is (0.5-1):1, and the particle size of the quartz sand is 20 mesh to 40 mesh.

[0033] Further, in the preset ratio, the mass ratio of the cementitious material, the second aggregates, and the modified score expansion fiber is (0.4-0.6):(0.5-0.6):(0.1-0.2); wherein the amount of water is controlled according to a water-cement ratio of 0.3.

[0034] Further, the cementitious material includes the following components by weight: 180 parts to 220 parts of Portland cement, 280 parts to 320 parts of sulfoaluminate cement, 40 parts to 60 parts of silica fume, 15 parts to 25 parts of fly ash, 0.5 parts to 1.5 parts of a crystal nucleus early strength agent, 0.5 parts to 1.5 parts of an expansive agent, and 1 part to 3 parts of a polycarboxylic acid water reducer.

[0035] The application also provides a high-disturbance-resistant cement-based material prepared by the above preparation method.

[0036] In summary, the application has the following advantages:

[0037] 1、The application joins the modified indentation expanding fiber, which expands and elongates under the action of moisture and cement hydration heat, thereby increasing the contact points between the fibers, so that the self-repairing hydrogel attached to the surface can produce a self-repairing effect after absorbing water, and then the fiber network is connected into a whole structure. And the polyvinyl alcohol-sodium borate hydrogel has certain strength and toughness, which can effectively inhibit the crack initiation before the cement base material is initially cured, and significantly improve the anti-disturbance performance; after the cement hydration heat release is completed, the hardened matrix is formed, the modified indentation expanding fiber begins to shrink and generates tensile stress, and the indentation design on the surface enhances the mechanical locking effect with the cement matrix, further optimizing the bearing capacity of the anti-disturbance material.

[0038] 2、The application joins the second aggregate, which can self-perceive the internal loss when the cement-based material is cracked by vibration or impact, and repair the cracks by generating or releasing repair materials, thereby improving the service life of the cement-based material. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 The flow chart of the preparation method of the high anti-disturbance cement-based material provided by the embodiments of the application. DETAILED DESCRIPTION

[0040] The principles and characteristics of the application are described below in conjunction with the embodiments, and the examples are only used to explain the application and not to limit the scope of the application. If the specific conditions are not specified in the embodiments, the conventional conditions or the conditions recommended by the manufacturer are used. If the reagents or instruments used are not specified by the manufacturer, they are all conventional products that can be purchased on the market.

[0041] The high anti-disturbance cement-based material provided by the application combines the three anti-disturbance mechanisms of biological self-repairing, fiber reinforcement and energy dissipation, and can realize multi-dimensional anti-disturbance ability under dynamic load. The polyvinyl alcohol-sodium borate hydrogel forms a dynamic crosslinked network through reversible borate ester bonds, which can dissipate energy under stress and avoid stress concentration. The indentation on the surface of the indentation expanding fiber provides a mechanical occlusion point, and the hydrogel particles adsorbed by static electricity form a flexible buffer layer at the fiber-matrix interface, thereby inhibiting crack propagation. The second aggregate is a combination of Bacillus and self-igniting coal gangue, and the microorganisms in it can be activated at the crack to metabolize calcium carbonate crystals, thereby realizing crack self-repairing.

[0042] Specifically, the application provides a preparation method of a high anti-disturbance cement-based material, as shown in Figure 1 The method comprises the following steps:

[0043] S1, preparing polyvinyl alcohol-sodium borate hydrogel, and treating by freeze-drying and crushing to obtain particulate matter.

[0044] In the present application, the hydroxyl group of polyvinyl alcohol (PVA) forms a reversible covalent bond (B-O-C) with the borate group of sodium borate (Na2B4O7), which endows the hydrogel with shear thickening properties. At the same time, the ratio of the two components balances the crosslinking density and the activity of the molecular chain, which can ensure that the material can both dissipate energy and not be brittle under dynamic loading. Through freeze-drying treatment, three-dimensional through channels can be formed, increasing the specific surface area of the particles and thus enhancing the electrostatic adsorption capacity and interfacial bonding strength with the fibers.

[0045] In the present application, the hydroxyl group of polyvinyl alcohol (PVA) forms a reversible covalent bond (B-O-C) with the borate group of sodium borate (Na2B4O7), which endows the hydrogel with shear thickening properties. At the same time, the ratio of the two components balances the crosslinking density and the activity of the molecular chain, which can ensure that the material can both dissipate energy and not be brittle under dynamic loading. Through freeze-drying treatment, three-dimensional through channels can be formed, increasing the specific surface area of the particles and thus enhancing the electrostatic adsorption capacity and interfacial bonding strength with the fibers.

[0046] Specifically, the polyvinyl alcohol-sodium borate hydrogel is prepared by the following method:

[0047] S101, 10-20 parts of polyvinyl alcohol is weighed and added to 100 parts of deionized water, and stirred at 90°C using a magnetic stirrer at a speed of 150-250 rpm for 1.5-2.5 hours;

[0048] S102, after stirring, ensure that the polyvinyl alcohol is completely dissolved to obtain a transparent viscous polyvinyl alcohol solution;

[0049] S103, 5-20 parts of sodium borate is weighed and added to 100 parts of deionized water, and stirred at room temperature using a magnetic stirrer at a speed of 150-250 rpm for 8-12 minutes to obtain a sodium borate solution;

[0050] S104, under the condition of 90°C, the polyvinyl alcohol solution is stirred using a magnetic stirrer, and the sodium borate solution is added during stirring. After the addition is completed, continue stirring for 18-25 minutes to fully react to obtain a first product;

[0051] S105, when the first product is cooled to room temperature, use a vacuum ultrasonic machine (ultrasonic power of 20 kHz, ultrasonic time of 5 minutes) to remove the bubbles therein, and after standing for 20 minutes, obtain a colorless transparent self-repairing polyvinyl alcohol-sodium borate hydrogel.

[0052] In the specific embodiment, the temperature of the freeze-drying treatment is -30°C to -50°C, and the time is 3-6 hours.

[0053] In the embodiment, the particle size of the granular substance obtained after the crushing treatment is less than 500 mesh. The particle size of less than 500 mesh can ensure that the particles can be embedded in the fiber notch groove to form a "pinning effect", thereby preventing the fiber from being detached from the matrix.

[0054] S2, treating the fiber raw material by melt spinning to obtain expanded fibers, and performing surface indentation treatment on the fibers to obtain notched expanded fibers.

[0055] The present application can realize controllable expansion and high modulus of the fibers through multi-component gradient melting, wherein the graphene particles provide a heat conduction network, which can accelerate the temperature uniformity in the melt spinning process and reduce the internal stress of the fibers.

[0056] In the embodiment, the fiber raw material includes 5-8 parts of modified graphene particles, 10-15 parts of temperature-sensitive polyurethane particles, and 15-18 parts of polyvinyl alcohol particles. The particle size of the modified graphene particles is 100-500 μm, the particle size of the temperature-sensitive polyurethane particles is 1-3 mm, and the particle size of the polyvinyl alcohol particles is 0.1-0.5 mm.

[0057] Preferably, the fiber raw material includes 7 parts of modified graphene particles, 12 parts of temperature-sensitive polyurethane particles, and 16 parts of polyvinyl alcohol particles.

[0058] In some optional embodiments of the present application, the parameters of melt spinning include:

[0059] The extrusion temperature is 250℃, the flow rate is 0.5-0.8 m / min, the circular spinneret size is 0.3 mm, the spacing is 15 mm, and the spinning length is 1 m.

[0060] S3, adsorbing the granular substance on the notched expanded fibers by electrostatic adsorption to obtain modified notched expanded fibers.

[0061] In the specific implementation process, the parameters of electrostatic adsorption include a voltage of 20 KV, a current of 80 μA, a needle-point discharge corona electrode form, and a stainless steel material for the corona electrode.

[0062] In the present application, in order to optimize the reinforcing efficiency and energy absorption path of the fiber, the fiber length of the notched expanded fiber is controlled within the range of 15-20 mm to meet the critical fiber length, thereby ensuring that the stress can be effectively transmitted. At the same time, the indentation depth of the notched expanded fiber is controlled within the range of 0.4-0.6 mm, which can increase the fiber pull-out work (i.e. the friction work of the fiber with the matrix during the pull-out process) and increase the bearing capacity of the fiber.

[0063] S4, inoculating Bacillus into self-igniting coal gangue to obtain first aggregate, and mixing the first aggregate with quartz sand to obtain second aggregate.

[0064] In the present application, the first aggregate is prepared by the following method:

[0065] S401, crushing the spontaneous combustion coal gangue to a particle size of less than 5mm;

[0066] S402, sterilizing the crushed coal gangue particles with a bacillus nutrient solution by high-temperature steam, and cooling to room temperature; wherein the bacillus nutrient solution comprises the following components: glucose 10g / L, calcium phosphate 5g / L, ammonium sulfate 0.5g / L, potassium chloride 0.2g / L, magnesium sulfate heptahydrate 0.1g / L, manganese sulfate 0.0001g / L, ferrous sulfate 0.0001g / L, and yeast extract 0.5g / L;

[0067] S403, inoculating the bacillus into the cooled bacillus nutrient solution under sterile conditions at an inoculation amount of 1% for culture, to obtain a bacterial solution with a concentration of (4-6) x 10 7 cfu / mL;

[0068] S404, adding the cooled coal gangue particles into the bacterial solution for vacuum soaking treatment and drying treatment, and obtaining the first aggregate after constant weight; wherein the vacuum soaking treatment pressure is -0.07MPa~ -0.03MPa, the vacuum soaking treatment time is 25min~40min; the drying treatment temperature is 38℃~45℃; the high-temperature steam sterilization temperature is 100℃~140℃, and the time is 20min~30min.

[0069] In the present application, the porous structure of the spontaneous combustion coal gangue has the advantages of low density and high porosity, which can provide sufficient shelter points for bacillus, and the alkaline environment of the spontaneous combustion coal gangue can also inhibit the growth of miscellaneous bacteria. Vacuum soaking can displace pore air by negative pressure, increase the penetration depth of the bacterial solution, and thus improve the loading efficiency. Finally, the drying treatment can preserve the dormant state of the bacillus, thereby shortening the bacillus revival time when encountering water.

[0070] In the present application, the mass ratio of the first aggregate to quartz sand in the second aggregate is (0.5-1):1, and the particle size of the quartz sand is 20-40 mesh. By dual aggregate grading, the density and microbial activity of the cement-based material can be optimized. The quartz sand fills the gaps between the first aggregate (containing coal gangue coarse aggregate), which not only improves the bulk density, but also enhances the mechanical interlocking ability with the cementitious material due to the roughness of the quartz sand surface. Meanwhile, its chemical inertness can avoid interfering with microbial metabolism.

[0071] Furthermore, the present application uses spontaneous combustion coal gangue as a component of the aggregate, reducing the amount of natural sand and achieving the reuse of solid waste, thereby reducing the cost of the material.

[0072] S5, the cementitious material, the second aggregate and the modified indentation expansion fiber are mixed according to a preset ratio, water is added and stirred uniformly, and a high anti-disturbance cement-based material is prepared.

[0073] In the preset ratio of the present application, the mass ratio of the cementitious material, the second aggregate and the modified indentation expansion fiber is (0.4-0.6):(0.5-0.6):(0.1-0.2); wherein the amount of water added is controlled according to a water-cement ratio of 0.3. The ratio relationship of the present application can ensure the formation of a continuous network, enhance the flexural strength of the cement-based material, and the water-cement ratio relationship can ensure the balance of the slurry flowability and porosity, thereby balancing the mechanical properties and self-repairing ability of the cement-based material.

[0074] In some optional embodiments of the present application, the cementitious material includes the following components by weight: 180-220 parts of Portland cement, 280-320 parts of sulphoaluminate cement, 40-60 parts of silica fume, 15-25 parts of fly ash, 0.5-1.5 parts of crystal nucleus early strength agent (nano-SiO2 crystal nucleus early strength agent, C-S-H crystal seed), 0.5-1.5 parts of expansion agent (including at least one of calcium-magnesium composite expansion agent, calcium oxide-calcium sulphoaluminate expansion agent and magnesium oxide expansion agent) and 1-3 parts of polycarboxylic acid water reducer. Among them, the Portland cement mainly plays a role in providing a C-S-H gel main skeleton, the sulphoaluminate cement mainly plays a role in rapidly increasing the strength of the cementitious material, the nano-silicon dioxide in the silica fume can fill the pores, thereby reducing the chloride ion diffusion coefficient, and the crystal nucleus early strength agent can accelerate the nucleation of the hydration product, rapidly increasing the strength of the cementitious material in a short time. Based on this, the composite cementitious system of the present application can achieve fast hardening, micro-expansion and high durability.

[0075] In a second aspect, based on a general inventive concept, the present application also provides a high anti-disturbance cement-based material prepared by the above method.

[0076] The high anti-disturbance cement-based material prepared by the present application has high toughness and self-repairing ability, has high compressive strength under disturbance conditions and non-disturbance conditions, and can repair an initial crack width of 0.5mm to about 0.1mm within 28d, greatly improving the service life of the cement-based material and reducing the maintenance cost, thereby improving the economic benefit of the cement-based material.

[0077] The above technical solutions of the present application will be described in detail below in conjunction with specific embodiments.

[0078] The equipment and raw materials used in the embodiments include:

[0079] Magnetic stirrer: Zhengzhou Rongxiang Instrument and Equipment Co., Ltd., heat type constant temperature heating magnetic stirrer.

[0080] Melt spinning machine: Sichuan Zirui Technology Co., Ltd.

[0081] High-temperature steam sterilization pot: Shandong Boke Biological Industry Co., Ltd.

[0082] Air bath constant temperature oscillator: Shanghai Bozhen Instrument and Equipment Manufacturing Plant.

[0083] Bacillus: Guangdong Runhe Biomedical Technology Co., Ltd.

[0084] Silicate cement: P·O 42.5.

[0085] Sulphoaluminate cement: R·SAC 42.5.

[0086] Silica fume: apparent density 2250kg / m 3 , silica content ≥90%, specific surface area ≥18000m 2 / kg.

[0087] Fly ash: apparent density 2300kg / m 3 , specific surface area ≥700m 2 / kg.

[0088] Crystal nucleus early strength agent: nano-SiO2 crystal nucleus early strength agent, C-S-H crystal seed.

[0089] Expanding agent: calcium-magnesium composite expanding agent, calcium oxide-calcium sulphoaluminate expanding agent, magnesium oxide expanding agent.

[0090] Polycarboxylic acid water reducer: Shandong Jinrong Chemical Technology Co., Ltd.

[0091] The modified graphene particles and temperature-sensitive polyurethane particles used in the examples are obtained by the following method:

[0092] (1) The modified graphene particles are prepared by the following method:

[0093] After mixing 200mg of graphene oxide and 500mL of deionized water, a first mixture is obtained by dispersing in an ultrasonic water bath at room temperature for 1h;

[0094] 2.0g of sodium 4-styrene sulfonate is added to the first mixture and stirred for more than 1h until the sodium 4-styrene sulfonate is completely dissolved, obtaining a second mixture;

[0095] 10g of hydrazine hydrate is added to the second mixture and heated at 95℃ in a water bath for 24h to obtain a preliminary product;

[0096] The preliminary product is washed with deionized water and then dried at a temperature of 105℃ for 24h to obtain the modified graphene particles.

[0097] (2) Temperature-sensitive polyurethane particles are prepared by the following method:

[0098] Mix 60 g of poly 1,2-propanediol and 35 g of L-lysine ethyl ester diisocyanate, stir at room temperature for 48 h or more at a speed of 200 rpm to obtain an initial product;

[0099] Dissolve the initial product in 200 mL of methanol solution (analytical pure, concentration 99%) and add 50 mL of ether (analytical pure, concentration 99%) as a precipitant, repeat the dissolution-precipitation process 3 times, then take out the final precipitate and dry it in an oven (30°C) for 48 h to obtain temperature-sensitive polyurethane particles.

[0100] Example 1

[0101] The present embodiment provides a method for preparing a high-disturbance-resistant cement-based material, comprising the following steps:

[0102] (1) Preparation of polyvinyl alcohol solution

[0103] Weigh 10 g of polyvinyl alcohol into 100 mL of deionized water, stir at 90°C for 2 h, and the stirring speed is 200 r / min.

[0104] After stirring, make sure that the polyvinyl alcohol is completely dissolved to obtain a transparent viscous polyvinyl alcohol solution.

[0105] (2) Preparation of sodium borate solution

[0106] Weigh 5 g of sodium borate into 100 mL of deionized water, stir at room temperature for 10 min, and the stirring speed is 200 r / min to obtain a sodium borate solution.

[0107] (3) Preparation of polyvinyl alcohol-sodium borate hydrogel

[0108] Stir the polyvinyl alcohol solution at 90°C while adding the sodium borate solution, continue stirring for 20 min after the addition is complete to allow it to react fully.

[0109] After the reaction mixture cools to room temperature, remove the gas bubbles in the mixture in a vacuum ultrasonic machine (ultrasonic power is 20 kHz, ultrasonic time is 5 min, same below), and let it stand for 20 min to obtain a colorless transparent polyvinyl alcohol-sodium borate hydrogel with self-repairing function.

[0110] Freeze-dry the polyvinyl alcohol-sodium borate hydrogel, then crush it into granules with a particle size of less than 500 mesh. The freeze-drying temperature is -30°C and the time is 3 h.

[0111] (4) Preparation of modified notched expanded fiber

[0112] 7 g of modified graphene particles (300 pm), 12 g of heat-sensitive polyurethane particles (2 mm), and 16 g of polyvinyl alcohol particles (0.3 mm) were uniformly mixed to obtain a mixture;

[0113] The mixture was subjected to melt spinning treatment by a melt spinning machine, and indentation treatment was performed on the surface of the cooled fiber, with a depth of indentation of 0.5 mm and a length of the fiber of 20 mm, to obtain scored expanded fiber;

[0114] The particles of polyvinyl alcohol-sodium borate hydrogel were adsorbed on the scored expanded fiber by electrostatic adsorption to obtain modified scored expanded fiber. The parameters of melt spinning (hereinafter the same) included an extrusion temperature of 250°C, a flow rate of 0.8 m / min, a circular spinneret size of 0.3 mm, a spacing of 15 mm, and a spinning length of 1 m. The parameters of electrostatic adsorption (hereinafter the same) included a voltage of 20 KV, a current of 80 pA, a needle-point discharge corona electrode form, and a corona electrode material of stainless steel.

[0115] (5) Preparation of first aggregate and second aggregate

[0116] The self-igniting coal gangue was crushed to a particle size of less than 5 mm, and the crushed coal gangue particles and prepared bacillus nutrient solution were subjected to steam sterilization treatment for 30 min by a high-temperature steam sterilization pot at 120°C. The bacillus nutrient solution (hereinafter the same) included the following components: glucose 10 g / L, calcium phosphate 5 g / L, ammonium sulfate 0.5 g / L, potassium chloride 0.2 g / L, magnesium sulfate heptahydrate 0.1 g / L, manganese sulfate 0.0001 g / L, ferrous sulfate 0.0001 g / L, and yeast extract 0.5 g / L.

[0117] In a sterile environment, the bacillus was transferred to the cooled bacillus nutrient solution by a pipette at an inoculation amount of 1%, and no other bacteria were mixed in during the inoculation process.

[0118] After inoculation, the mixture was placed in a 30°C air bath constant temperature shaker and shaken at a speed of 120 rpm for 2 d to obtain a bacterial solution with a concentration of 5 x 10 7 cfu / mL.

[0119] The sterilized coal gangue was placed in the bacterial solution for vacuum soaking treatment, so that the bacillus was adsorbed in the sterilized self-igniting coal gangue. The vacuum pressure was -0.05 MPa, and the soaking time was 30 min. Then, the mixture was dried to constant weight (constant weight refers to the mass of the coal gangue no longer changing) in a 40°C oven to obtain the first aggregate.

[0120] The first aggregate and quartz sand were uniformly mixed at a mass ratio of 1:1 to obtain the second aggregate. The particle size of the quartz sand was 40 mesh.

[0121] (6) Preparation of cementitious material

[0122] Take 200g ordinary Portland cement, 300g sulphoaluminate cement, 50g silica fume, 20g first-grade fly ash, 1g nano-SiO2 crystal core early strength agent, 1g calcium-magnesium composite expansive agent, and 2g polycarboxylic acid water reducer, mix uniformly to obtain a cementitious material.

[0123] (7) Preparation of high anti-disturbance cement-based material

[0124] The prepared cementitious material, second aggregate, and modified indentation expansion fiber are added to the blender in a mass ratio of 0.5:0.5:0.1, and water is added in a water-cement ratio of 0.3, and a high anti-disturbance cement-based material is prepared after uniform stirring.

[0125] Example 2

[0126] The present embodiment provides a method for preparing a high anti-disturbance cement-based material, comprising the following steps:

[0127] (1) Preparation of polyvinyl alcohol solution

[0128] Take 10g of polyvinyl alcohol and add it to 100mL of deionized water, stir at 90℃ for 2h, and the stirring speed is 250r / min;

[0129] After stirring, ensure that the polyvinyl alcohol is completely dissolved, and a transparent viscous polyvinyl alcohol solution is obtained.

[0130] (2) Preparation of sodium borate solution

[0131] Take 5g of sodium borate and add it to 100mL of deionized water, stir at room temperature for 10min, and the stirring speed is 250r / min, to obtain a sodium borate solution.

[0132] (3) Preparation of polyvinyl alcohol-sodium borate hydrogel

[0133] Stir the polyvinyl alcohol solution at 90℃, and add the sodium borate solution at the same time, continue stirring for 20min after the addition is completed, so that it can fully react;

[0134] After the reaction, the mixture is cooled to room temperature, and then placed in a vacuum ultrasonic machine to remove the gas bubbles in the mixture, and a colorless transparent polyvinyl alcohol-sodium borate hydrogel with self-repairing function is obtained after standing.

[0135] The polyvinyl alcohol-sodium borate hydrogel is subjected to freeze-drying treatment, and then crushed into granular material with a particle size of less than 500 mesh. The temperature of the freeze-drying treatment is -50℃, and the time is 6h.

[0136] (4) Preparation of modified indentation expansion fiber

[0137] 5g of modified graphene particles, 10g of heat-sensitive polyurethane particles, and 18g of polyvinyl alcohol particles were uniformly mixed to obtain a mixture;

[0138] The mixture was subjected to melt spinning treatment by a melt spinning machine, and indentation treatment was performed on the surface of the cooled fiber. The depth of the indentation was 0.5mm, and the length of the fiber was 15mm. An indentation expansion fiber was obtained.

[0139] The particles of the polyvinyl alcohol-sodium borate hydrogel were adsorbed on the indentation expansion fiber by electrostatic adsorption to obtain a modified indentation expansion fiber.

[0140] (5) Preparation of first aggregate and second aggregate

[0141] The self-igniting coal gangue was crushed to a particle size of less than 5mm, and the crushed coal gangue particles and the prepared bacillus nutrient solution were subjected to steam sterilization treatment for 30min by a high-temperature steam sterilization pot at 120℃.

[0142] The bacillus was transferred to the cooled bacillus nutrient solution by a pipette at an inoculation amount of 1% in a sterile environment, and no other bacteria were allowed to be mixed during the inoculation process.

[0143] After inoculation, the mixture was placed in a 30℃ air bath constant temperature shaker at a speed of 120rpm and shaken uniformly for 2d to obtain a bacterial solution with a concentration of 5×10 7 cfu / mL;

[0144] The sterilized coal gangue was subjected to vacuum soaking treatment in the bacterial solution, and the bacillus was adsorbed in the sterilized self-igniting coal gangue. The vacuum pressure was-0.05MPa, and the soaking time was 30min. Then, the mixture was dried in an oven at 40℃ to a constant weight (constant weight refers to the mass of the coal gangue no longer changing) to obtain a first aggregate.

[0145] The first aggregate and quartz sand were uniformly mixed in a mass ratio of 1:1 to obtain a second aggregate. The particle size of the quartz sand was 20mesh.

[0146] (6) Preparation of cementitious material

[0147] 210g of ordinary Portland cement, 290g of sulphoaluminate cement, 55g of silica fume, 15g of first-grade fly ash, 1g of nano-SiO2 crystal core early strength agent, 0.5g of magnesium oxide expanding agent, and 2.5g of polycarboxylic acid water reducer were weighed and uniformly mixed to obtain a cementitious material.

[0148] (7) Preparation of high anti-disturbance cement-based material

[0149] The prepared cementitious material, the second aggregate and the modified indentation expansion fiber are added into a blender in a mass ratio of 0.4:0.6:0.1, and water is added in a water-cement ratio of 0.3, to obtain the high-disturbance-resistant cement-based material.

[0150] Example 3

[0151] The embodiment provides a preparation method of a high-disturbance-resistant cement-based material, and the method comprises the following steps:

[0152] (1) Preparation of polyvinyl alcohol solution

[0153] 10 g of polyvinyl alcohol is weighed and added into 100 mL of deionized water, and stirred at 90 DEG C for 2 h, and the stirring speed is 150 r / min;

[0154] After stirring, it is ensured that the polyvinyl alcohol is completely dissolved, and a transparent viscous polyvinyl alcohol solution is obtained.

[0155] (2) Preparation of sodium borate solution

[0156] 5 g of sodium borate is weighed and added into 100 mL of deionized water, and stirred at room temperature for 10 min, and the stirring speed is 150 r / min, to obtain a sodium borate solution.

[0157] (3) Preparation of polyvinyl alcohol-sodium borate hydrogel

[0158] The polyvinyl alcohol solution is stirred at 90 DEG C, and the sodium borate solution is added, and after the addition is completed, the stirring is continued for 20 min, so that the reaction is sufficient;

[0159] After the reaction mixture is cooled to room temperature, it is placed in a vacuum ultrasonic machine to remove the gas bubbles in the mixture, and after standing, a colorless transparent polyvinyl alcohol-sodium borate hydrogel with self-repairing function is obtained.

[0160] The polyvinyl alcohol-sodium borate hydrogel is subjected to freeze-drying treatment, and then is crushed into granular materials with a particle size of less than 500 mesh. The temperature of the freeze-drying treatment is -40 DEG C, and the time is 5 h.

[0161] (4) Preparation of modified indentation expansion fiber

[0162] 8 g of graphene particles, 10 g of thermosensitive polyurethane particles and 15 g of polyvinyl alcohol particles are uniformly mixed to obtain a mixture.

[0163] The mixture is subjected to melt spinning treatment through a melt spinning machine, and indentation treatment is performed on the surface of the cooled fiber, the depth of the indentation is 0.5 mm, and the length of the fiber is 18 mm, to obtain the indentation expansion fiber.

[0164] The particles of the polyvinyl alcohol-sodium borate hydrogel are adsorbed on the notched expanded fiber by electrostatic adsorption to obtain modified notched expanded fiber.

[0165] (5) Preparation of the first aggregate and the second aggregate

[0166] The spontaneous combustion coal gangue is crushed to a particle size of less than 5 mm, and the crushed coal gangue particles and the prepared bacillus nutrient solution are subjected to steam sterilization treatment for 30 min at 120 DEG C steam in a high-temperature steam sterilization pot.

[0167] The bacillus is transferred into the cooled bacillus nutrient solution by a pipette at an inoculation amount of 1%, and no other bacteria are mixed in the inoculation process.

[0168] After inoculation, the mixture is placed in a 30 DEG C air bath constant temperature shaker and shaken at a speed of 120 rpm for 2 days to obtain a bacterial solution with a concentration of 5x10 7 cfu / mL.

[0169] The sterilized coal gangue is subjected to vacuum soaking treatment in the bacterial solution, so that the bacillus is adsorbed in the sterilized spontaneous combustion coal gangue, the vacuum pressure is-0.05 MPa, the soaking time is 30 min, and then the mixture is dried in a 40 DEG C oven to constant weight (constant weight refers to that the mass of the coal gangue no longer changes) to obtain the first aggregate.

[0170] The first aggregate and the quartz sand are mixed uniformly at a mass ratio of 1:1 to obtain the second aggregate; the particle size of the quartz sand is 40 mesh.

[0171] (6) Preparation of the cementitious material

[0172] 220 g of ordinary Portland cement, 280 g of sulphoaluminate cement, 48 g of silica fume, 22 g of first-grade fly ash, 1.5 g of nano-SiO2 crystal core early strength agent, 1 g of calcium-magnesium composite expansive agent, and 1 g of polycarboxylic acid water reducer are weighed and mixed uniformly to obtain the cementitious material.

[0173] (7) Preparation of the high-disturbance-resistant cement-based material

[0174] The prepared cementitious material, the second aggregate, and the modified notched expanded fiber are added to a blender at a mass ratio of 0.6:0.5:0.2, and water is added at a water-cement ratio of 0.3, and the mixture is stirred uniformly to obtain the high-disturbance-resistant cement-based material.

[0175] Comparative Example 1

[0176] The difference between the present comparative example and Example 1 is that the modified notched expanded fiber is not added, and the other steps are the same as those of Example 1.

[0177] Comparative Example 2

[0178] The difference between the present comparative example and Example 1 is that only quartz sand is used as aggregate without adding the first aggregate, and the remaining steps are consistent with Example 1.

[0179] Comparative Example 3

[0180] The difference between the present comparative example and Example 1 is that the mass ratio of cementitious material, second aggregate and modified notched intumescent fiber is 0.5:0.5:0.3, and the remaining steps are consistent with Example 1.

[0181] Comparative Example 4

[0182] The difference between the present comparative example and Example 1 is that the mass ratio of cementitious material, second aggregate and modified notched intumescent fiber is 0.5:0.5:0.06, and the remaining steps are consistent with Example 1.

[0183] Comparative Example 5

[0184] The difference between the present comparative example and Example 1 is that the mass ratio of cementitious material, second aggregate and modified notched intumescent fiber is 0.5:0.7:0.4, and the remaining steps are consistent with Example 1.

[0185] Comparative Example 6

[0186] The difference between the present comparative example and Example 1 is that the mass ratio of cementitious material, second aggregate and modified notched intumescent fiber is 0.5:0.3:0.4, and the remaining steps are consistent with Example 1.

[0187] The cement-based materials prepared in Example 1 and Comparative Examples 1-6 are compared, wherein the compressive strength test refers to GBT 17671-2021 “Cement Mortar Strength Test Method (ISO Method)”; the disturbance condition is to use a high-frequency electric vibration table to simulate the disturbance condition, and the vibration parameters are vibration frequency 5HZ, amplitude 5mm, and continuous vibration for 1h; the crack width test uses a reading microscope with magnification not less than 40 times and graduation value not greater than 0.01mm to observe the crack width, and the data is shown in Table 1.

[0188] Table 1

[0189]

[0190] Compared with Comparative Example 1, Example 1 of the present application adds modified notch expansion fibers, and the 28d compressive strength of the cement-based material is improved, with an improvement of 21.3% under undisturbed conditions and an improvement of 37.5% under disturbed conditions. The reason may be that the fibers effectively transmit stress, and the surface notch also improves the pullout work of the fibers, so that they can absorb the energy of dynamic load. At the same time, the strength retention rate of the cement-based material of Example 1 after disturbance is as high as 98.8% (obtained by comparing the compressive strength after 28d disturbance with the compressive strength under undisturbed conditions), which also shows that the fiber network can inhibit crack propagation under dynamic load and can dissipate energy through interface slip.

[0191] Compared with Comparative Example 2, Example 1 of the present application adds the first aggregate (which is a bacteria-containing aggregate), which has crack self-repairing ability and can maintain the long-term durability of the cement-based material. As can be seen from Table 1, the crack width of Example 1 is reduced by about 80%, and the reason is that the bacillus metabolism produces calcium carbonate to fill the crack space. Although the initial strength of Comparative Example 2 is slightly higher than that of the cement-based material of Example 1, the strength loss after disturbance is higher, indicating that the quartz sand does not have self-repairing ability, and the microcracks will continue to expand under dynamic load.

[0192] At the same time, as can be seen from Example 1 and Comparative Examples 3-4, only when the proportioning is carried out according to the preset proportioning relationship of the present application, the compressive strength, crack resistance and disturbance resistance of the high-disturbance-resistant cement-based material can be optimized. Among them, an excessive proportion of modified fibers will reduce the bonding strength of the system, and too low a proportion will result in ineffective crack resistance. The proportion of the second aggregate should match the cementitious material to ensure the balance between skeletal support and bonding strength.

[0193] In summary, it can be seen that the modified notch expansion fibers used in the present application are the core of improving the immediate mechanical properties, which can enhance the compressive strength of the cement-based material and reduce the strength loss under dynamic load; the first aggregate used is the key to ensuring long-term durability, which can significantly improve the self-repairing ability of cracks. The high-disturbance-resistant cement-based material of the present application can limit the crack width to <1mm in the early stage of cracking through the coupling of fibers and microorganisms, and can repair the cracks through the efficient mineralization of microorganisms in the limited cracks after the cracks appear. At the same time, the fibers can absorb impact energy through plastic deformation to adapt to instantaneous load, and the microorganisms can adapt to cyclic load by repairing fatigue microcracks.

[0194] Although the specific embodiments of the present application are described in detail, it should not be understood as limiting the scope of protection of the present application. Various modifications and variations made by those skilled in the art without creative labor within the scope described in the claims are still within the scope of protection of the present application.

Claims

1. A method for preparing a highly disturbance-resistant cement-based material, characterized in that, Includes the following steps: Polyvinyl alcohol-sodium borate hydrogel was prepared and then freeze-dried and pulverized to obtain particulate matter. Expanded fibers are obtained by melt spinning of fiber raw materials, and the expanded fibers are then subjected to surface indentation treatment to obtain indented expanded fibers. The particulate matter is adsorbed onto the grooved expansion fiber by electrostatic adsorption to obtain the modified grooved expansion fiber. Bacillus was inoculated into spontaneously combusting coal gangue to obtain the first aggregate. The first aggregate was then mixed with quartz sand to obtain the second aggregate. After mixing the cementitious material, the second aggregate and the modified indented expansion fiber in a preset ratio, water is added and the mixture is stirred evenly to obtain a highly resistant cementitious material. The fiber length of the scoring expansion fiber is 15mm~20mm, and the indentation depth of the scoring expansion fiber is 0.4mm~0.6mm; The process of obtaining expanded fibers by melt spinning of fiber raw materials includes: Weigh 5 to 8 parts of modified graphene particles, 10 to 15 parts of thermosensitive polyurethane particles and 15 to 18 parts of polyvinyl alcohol particles and mix them evenly to obtain a mixture. The mixture is melt-spun to obtain expanded fibers; wherein, The parameters of the melt spinning process include: extrusion temperature of 250℃, flow rate of 0.5m / min to 0.8m / min, circular spinneret size of 0.3mm, spacing of 15mm, and spinning length of 1m.

2. The preparation method according to claim 1, characterized in that, The polyvinyl alcohol-sodium borate hydrogel was prepared by the following method: A 10wt%~20wt% polyvinyl alcohol solution and a 5wt%~20wt% sodium borate solution were mixed under stirring at a mass ratio of (2~5):

1. After the reaction was completed, the mixture was cooled to room temperature and the bubbles were removed to obtain the final product.

3. The preparation method according to claim 1, characterized in that, The freeze-drying process is carried out at a temperature of -30℃ to -50℃ for 3 hours to 6 hours; the particle size of the particulate matter is less than 500 mesh.

4. The preparation method according to claim 1, characterized in that, The method of inoculating Bacillus subtilis into spontaneously combusting coal gangue to obtain the first aggregate includes: Crushing spontaneously combusting coal gangue to a particle size of less than 5 mm yields coal gangue particles; The coal gangue particles and Bacillus nutrient solution were sterilized using high-temperature steam and then cooled to room temperature. Under aseptic conditions, Bacillus was inoculated into the cooled Bacillus nutrient solution at an inoculum volume of 1% and cultured to obtain a concentration of (4~6)×10⁻⁶. 7 bacterial suspension with cfu / mL; The cooled coal gangue particles are added to the bacterial solution for vacuum soaking and drying, and the first aggregate is obtained after constant weight. The vacuum soaking pressure is -0.07MPa to -0.03MPa, the vacuum soaking time is 25min to 40min, and the drying temperature is 38℃ to 45℃.

5. The preparation method according to claim 1, characterized in that, The mass ratio of the first aggregate to the quartz sand in the second aggregate is (0.5~1):1, and the particle size of the quartz sand is 20 mesh~40 mesh.

6. The preparation method according to claim 1, characterized in that, In the preset ratio, the mass ratio of cementitious material, second aggregate and modified indented expansion fiber is (0.4~0.6):(0.5~0.6):(0.1~0.2); wherein the amount of water added is adjusted according to a water-cement ratio of 0.

3.

7. The preparation method according to claim 1, characterized in that, The cementitious material comprises the following components by weight: 180 to 220 parts silicate cement, 280 to 320 parts sulfoaluminate cement, 40 to 60 parts silica fume, 15 to 25 parts fly ash, 0.5 to 1.5 parts nucleation accelerator, 0.5 to 1.5 parts expansion agent, and 1 to 3 parts polycarboxylate superplasticizer.

8. A highly disturbance-resistant cement-based material, characterized in that, It is prepared by the method described in any one of claims 1-7.

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