Ferrite-aluminate cement-based high corrosion-resistant removable formwork and preparation method thereof

Abstract

The application discloses a ferrite-aluminate cement-based high-erosion-resistance and demould-free formwork and a preparation method thereof, and belongs to the technical field of ferrite-aluminate cement, wherein the ferrite-aluminate cement is 40-60 parts, the aggregate is 80-100 parts, the modified steel fiber is 2-5 parts, the additive is 1-3 parts, and the water is 13-20 parts. After the steel fiber is sprayed and compounded with nano-silicon dioxide, the impact resistance of the formwork is remarkably improved. Through corrosion inhibitor adsorption treatment on the steel fiber, the corrosion resistance of the formwork is greatly improved. After the two treatment modes of spraying and compounding with nano-silicon dioxide and corrosion inhibitor adsorption are compounded, not only the impact resistance and the corrosion resistance are improved, but also the toughness of the formwork is unexpectedly enhanced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ferrite aluminate cement, in particular to a ferrite aluminate cement-based high corrosion-resistant removable formwork and a preparation method thereof. BACKGROUND

[0002] In the field of building engineering, especially in the construction of infrastructure in harsh environments such as marine engineering and saline-alkali areas, such as the construction of bridge piers of cross-sea bridges, high requirements are put forward for the durability and corrosion resistance of building materials.

[0003] Due to the characteristics of the hydration products of Portland cement, in marine and saline-alkali environments, external corrosive ions enter the interior of the concrete structure. On the one hand, the corrosion of the hydration products of the concrete destroys the protection of the steel bars; on the other hand, the corrosion of the steel bars under the action of corrosive ions causes expansion, which further aggravates the destruction of the concrete, thereby reducing the durability and service life of the cross-sea bridge and other concrete structures in marine engineering and saline-alkali areas. The corrosion and destruction of concrete structures in marine engineering and saline-alkali areas have become a worldwide engineering problem. In order to improve the corrosion resistance of concrete in harsh environments, corrosion-resistant paint is usually applied to the parts in contact with corrosive media, but due to the mismatch between the durability and thermal expansion coefficient of the corrosion-resistant paint and the concrete, the corrosion-resistant paint needs to be reapplied every 5-10 years, which cannot fundamentally solve the corrosion problem.

[0004] Ferrite aluminate cement is a new type of cement material with unique performance advantages. Compared with traditional Portland cement, ferrite aluminate cement belongs to a different mineral system and is a revolutionary breakthrough in cement technology. A large amount of data shows that ferrite aluminate cement has the special performance of not being corroded by seawater and saline-alkali. However, due to its price being 2-3 times that of ordinary Portland cement, the use of ferrite aluminate cement in harsh environments such as marine and saline-alkali will significantly increase the cost of engineering construction. Removable formwork is a new technology that has emerged in recent years, which combines ferrite aluminate cement technology with removable formwork technology, allowing the removable formwork to directly contact the external corrosive environment and isolating the internal concrete from the corrosive environment, thereby achieving improved durability and significantly reducing costs.

[0005] Based on this, the present application designs a ferrite aluminate cement-based high corrosion-resistant removable formwork and a preparation method thereof to solve the above problems. SUMMARY

[0006] In view of the above-mentioned shortcomings of the prior art, the present application provides a ferrite aluminate cement-based high corrosion-resistant removable formwork, which comprises the following components:

[0007] 40-60 parts of ferrite aluminate cement;

[0008] Aggregate 80-100 parts, the aggregate is composed of fine aggregate with particle size of 0.15-0.6 mm and coarse aggregate with particle size of 5-10 mm in a mass ratio of 30-40:50-70;

[0009] Modified steel fiber 2-5 parts, the modified steel fiber is obtained by plasma surface activation, nano-silica spraying composite, corrosion inhibitor adsorption and plant fiber mixing of steel fiber;

[0010] Admixture 1-3 parts; the admixture is composed of water reducing agent, viscosity reducing agent and waterproof agent in a mass ratio of 0.5-2:0.5-1.5:1-3;

[0011] Water 13-20 parts.

[0012] A preparation method of the ferrum aluminate cement-based high corrosion-resistant removable formwork, comprising the following steps:

[0013] S1: steel fiber modification;

[0014] Plasma surface activation: the steel fiber is placed in a low-temperature plasma device, and air / argon mixed gas is introduced for treatment for 2-5 min;

[0015] Nano-silica spraying composite: nano-silica and polyvinyl alcohol aqueous solution are mixed and ultrasonically dispersed to prepare a uniform spraying liquid; the spraying liquid is sprayed on the surface of the activated fiber by using an air spraying device;

[0016] Corrosion inhibitor adsorption: an aqueous phytic acid solution is prepared, and the aqueous phytic acid solution is uniformly attached to the surface of the fiber by using a spraying adsorption method to obtain composite steel fiber, and a corrosion protection film is formed by drying;

[0017] Plant fiber mixing: waste bamboo fiber or wood fiber is crushed and ground into plant fiber powder; the powder and the composite steel fiber are mixed in a blender to obtain modified steel fiber by stirring;

[0018] S2: raw material pretreatment;

[0019] The ferrum aluminate cement, fine aggregate and coarse aggregate are dried at 40-60 DEG C for 2-4 h;

[0020] S3: mixing and stirring;

[0021] The dried fine aggregate and coarse aggregate are added into a forced mixer for dry mixing; the ferrum aluminate cement is added for continuous dry mixing; water, water reducing agent, viscosity reducing agent and waterproof agent are added for wet mixing; the modified steel fiber is added into the mixer in batches, and continuous stirring is carried out to obtain a concrete mixture;

[0022] S4: formwork forming;

[0023] The stirred concrete mixture is poured into the mold at one time, and the mold is vibrated using a vibrating table;

[0024] S5: curing after standing to obtain ferric aluminate cement-based high corrosion-resistant removable formwork.

[0025] Further, the nano-silica spraying composite step is specifically: mixing nano-silica with a particle size of 20-50 nm and 2-5 wt% polyvinyl alcohol aqueous solution, ultrasonic dispersion for 15-30 min at 150-250 W, to prepare a uniform spraying liquid; using an air spraying device, the spraying liquid is sprayed on the surface of the activated fiber at a pressure of 0.3-0.6 MPa, and dried at 50-60℃ for 1-2 h.

[0026] Further, the specific steps of the corrosion inhibitor adsorption are: preparing a 1-2 wt% phytic acid aqueous solution, placing the nano-composite fiber in a sealed container, and using a spray adsorption method to uniformly attach the phytic acid aqueous solution to the surface of the fiber to obtain a composite steel fiber, and drying at 40-50℃ for 2-3 h to form an corrosion protection film.

[0027] Further, the plant fiber mixing step is specifically: crushing and grinding the waste bamboo fiber or wood fiber to prepare plant fiber powder with an average particle size of 1-5 μm; mixing the powder with the composite steel fiber at a mass ratio of 1:3-5 in a blender, stirring at 200-350 r / min for 5-10 min to obtain modified steel fiber.

[0028] Further, S3 is specifically: adding the dried fine aggregate and coarse aggregate into a forced mixer, dry mixing at a speed of 100-200 r / min for 0.5-1 min to mix the fine and coarse aggregates uniformly; adding ferric aluminate cement, continuing to dry mix at the same speed for 1-2 min; adding water, water reducing agent, viscosity reducer and waterproof agent, increasing the stirring speed of the mixer to 200-300 r / min, and wet mixing for 1-2 min; adding the modified steel fiber into the mixer in 2-3 times, with an interval of 2-3 min each time, and continuously stirring at a speed of 150-250 r / min for 10-15 min to obtain a concrete mixture.

[0029] Further, S4 is specifically: evenly applying a layer of water-based release agent on the bottom and four sides of the mold, with the thickness of the water-based release agent being controlled at 0.1-0.3 mm, pouring the stirred concrete mixture into the mold at one time, and using a vibrating table to vibrate the mold, with the vibration frequency of the vibrating table being set at 20-50 Hz and the vibration time being 1-3 min.

[0030] Further, S5 is specifically: standing for 10-12 h after molding, then removing the mold, and then placing the mold in a temperature of 20-30℃ and a relative humidity of ≥95% for curing for 3-7 days.

[0031] The beneficial effects of the present application compared to the prior art are:

[0032] 1、The present application significantly improves the impact resistance of the template after spraying nano-silica on the surface of the steel fiber. Nano-silica has the characteristics of small particle size, many micropores, and large specific surface area. When it is sprayed on the surface of the steel fiber, these characteristics play an important role. On the one hand, the nano-silica particles form a close bond with the steel fiber, enhancing the surface strength of the fiber. Due to the large specific surface area of the nano-silica particles, the interface adhesion with the fiber matrix is strong, and a large amount of impact energy can be absorbed, as if a layer of energy buffer is built on the surface of the fiber. When impacted, this buffer layer can effectively disperse the impact energy and prevent cracks from occurring and expanding within the fiber. On the other hand, the filling effect of nano-silica makes the microstructure of the fiber more dense. Its small particle size can fill the gaps and defects in the steel fiber, reducing stress concentration points, thereby further improving the impact resistance of the fiber and even the entire template. This effect is similar to filling small gaps in a building structure to enhance the stability of the overall structure, so that the template can better maintain structural integrity when facing external impact, effectively avoiding cracks or damage caused by impact.

[0033] 2、The present application greatly improves the corrosion resistance of the template by adsorbing corrosion inhibitors on the surface of the steel fiber. The present application selects environmentally friendly phytic acid as the corrosion inhibitor. The phytic acid molecule structure contains multiple active groups. When the phytic acid aqueous solution is uniformly attached to the surface of the fiber by spray adsorption and dried, a series of physical and chemical effects will occur on the fiber surface. From the perspective of physical adsorption, there is an electrostatic attraction between the dipole or ionic charge of the phytic acid molecule and the electronic charge on the surface of the fiber, allowing the phytic acid to be tightly adsorbed on the surface of the fiber. From a chemical perspective, the active groups in the phytic acid molecule may react with certain atoms or groups on the surface of the fiber, forming chemical bonds and further enhancing the stability of the adsorption. In this way, a dense corrosion protection film is formed on the surface of the fiber. In harsh corrosive environments such as saline, ocean, etc., this protective film can effectively prevent corrosive media such as chloride ions, sulfate ions, hydroxyl ions, etc. from directly contacting the fiber. At the same time, the phytic acid corrosion inhibitor may also change the charge state and interface properties of the metal surface, inhibiting the electrochemical reaction during the corrosion process, thereby significantly improving the corrosion resistance of the template in these harsh environments and prolonging the service life of the template.

[0034] 3. The combination of nano-silica spraying and corrosion inhibitor adsorption not only synergistically enhances impact resistance and corrosion resistance but also unexpectedly improves the toughness of the template. While enhancing impact resistance, the tight bond between nano-silica and steel fibers, along with its densification effect on the microstructure, provides a better foundation for the adhesion of the corrosion inhibitor protective film. This allows the corrosion inhibitor to exist more stably on the fiber surface, enhancing the corrosion inhibition effect. The presence of the corrosion inhibitor protective film reduces the erosion of the fibers by the external environment, ensuring the stability of the original fiber properties and further contributing to the improvement of the template's toughness. Furthermore, the combined effect of nano-silica and the corrosion inhibitor may alter the molecular chain arrangement and interaction patterns within the steel fibers. This enhances the sliding and coordinated deformation capabilities between molecular chains. When the template is subjected to external forces, the molecular chains can better coordinate deformation and absorb energy, thus exhibiting higher toughness. This comprehensive performance improvement resulting from the combination allows the aluminoferrite cement-based high-corrosion-resistant, non-removable template to demonstrate excellent performance in various complex environments, showing broad application prospects. Detailed Implementation

[0035] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0036] Example 1: This example provides a method for preparing a high corrosion-resistant, non-removable formwork based on aluminoferrite cement, including the following steps:

[0037] S1: Steel fiber modified;

[0038] Plasma surface activation: The steel fiber is placed in a low-temperature plasma device, and an air / argon mixture with a volume ratio of 2:1 is introduced. The processing power is set to 80W and the processing time is 5min.

[0039] Nano-silica spraying composite: 50nm nano-silica particles are mixed with 5wt% polyvinyl alcohol aqueous solution and ultrasonically dispersed at 250W for 30min to prepare a uniform spraying liquid; the spraying liquid is sprayed onto the activated fiber surface at a pressure of 0.6MPa using an air spraying device and dried at 60℃ for 2h.

[0040] Corrosion inhibitor adsorption: Select environmentally friendly phytic acid as the corrosion inhibitor, prepare a 2wt% phytic acid solution, place the nano-composite fiber in a sealed container, and use a spray adsorption method to evenly attach the phytic acid solution to the surface of the fiber to obtain a composite steel fiber. Dry at 50°C for 3h to form a corrosion protection film, effectively resisting salt and alkali, and marine environment erosion;

[0041] Plant fiber mixing: The waste wood fiber is crushed and ground into plant fiber powder with an average particle size of 5μm; the powder is mixed with the composite steel fiber at a mass ratio of 1:5 in a blender, stirred at 350r / min for 10min, the plant fiber powder is filled in the steel fiber surface and gap to form an interlocking structure, further improving the strength and toughness of the fiber, and realizing the resource utilization of waste, obtaining modified steel fiber;

[0042] S2: Raw material pretreatment;

[0043] Drying the ferrite aluminate cement, fine aggregate and coarse aggregate at 60°C for 4h;

[0044] S3: Weighing raw materials;

[0045] Ferrite aluminate cement 60 parts, as the main cementitious material, has good corrosion resistance, is the key to ensure the performance stability of the template in harsh environment, ferrite aluminate cement is made of proper proportion of iron ore, bauxite, limestone and other raw materials by high temperature calcination, main mineral components include anhydrous calcium sulphoaluminate, dicalcium silicate and ferrite aluminate;

[0046] Aggregate 100 parts, fine aggregate (quartz sand) and coarse aggregate (broken stone) mass ratio 40:70, aggregate provides skeleton support for the template, enhances the strength and stability of the template, fine aggregate particle size 0.6mm, coarse aggregate particle size 20mm;

[0047] Modified steel fiber 5 parts, diameter 30μm, length 12mm, uniformly dispersed in the cement matrix, can effectively prevent the generation and expansion of cracks, improve the toughness and impact resistance of the template;

[0048] Admixtures 3 parts; water reducing agent (Sika ViscoCrete-1000), viscosity reducing agent and waterproof agent (organic silicon waterproof agent) mass ratio 2:1.5:3;

[0049] Water 20 parts;

[0050] S4: Mixing and stirring;

[0051] The dry fine aggregate and coarse aggregate are added into a forced stirrer, and dry mixing is performed at a rotating speed of 200 r / min for 1 min to uniformly mix the coarse and fine aggregates; then ferrum aluminate cement is added, and dry mixing is continued at the same rotating speed for 2 min; water, water reducing agent, viscosity reducing agent and waterproof agent are added, the rotating speed of the stirrer is increased to 300 r / min, and wet mixing is performed for 2 min; the modified steel fiber is added into the stirrer in three times with an interval of 3 min each time, and continuous stirring is performed at a rotating speed of 250 r / min for 15 min to obtain a concrete mixture;

[0052] S5: template forming;

[0053] A layer of water-based release agent is evenly applied on the bottom and four sides of the mold, and the thickness of the water-based release agent is controlled to be 0.3 mm; the stirred concrete mixture is poured into the mold at one time until the designed thickness of the template is reached, a vibrating table is used to vibrate the mold, the vibration frequency of the vibrating table is set to 50 Hz, and the vibrating time is 3 min, so that the cement slurry fully fills the mold, expels the internal bubbles, and ensures the compactness of the template;

[0054] S6: after standing, the ferrum aluminate cement-based high corrosion-resistant and demoulding-free template is obtained;

[0055] After forming, the template is demoulded after standing for 12 h, and then placed in a curing room with a temperature of 30 ℃ and a relative humidity of ≥95% for 7 days of curing; in the initial curing stage, a plastic film is covered on the surface of the template, the adhesion of the film to the surface of the template is ≥90%, and during the curing process, the template is checked every 6 h to observe whether there are cracks, deformation and other conditions; if the surface is dry, water is supplemented in time by spraying, and the spraying pressure is controlled to be 0.5 MPa.

[0056] Embodiment 2: The embodiment provides a preparation method of a ferrum aluminate cement-based high corrosion-resistant and demoulding-free template, comprising the following steps:

[0057] S1: steel fiber modification;

[0058] Plasma surface activation: the steel fiber is placed in a low-temperature plasma device, and a mixed gas of air / argon with a volume ratio of 1:1 is introduced, the treatment power is set to 30 W, and the treatment time is 2 min;

[0059] Nano-silica spraying composite: 20 nm nano-silica and 2 wt% polyvinyl alcohol aqueous solution are mixed, ultrasonic dispersion is performed at 150 W for 15 min to prepare a uniform spraying liquid; the spraying liquid is sprayed on the surface of the activated fiber by using an air spraying device at a pressure of 0.3 MPa, and dried at 50 ℃ for 1 h;

[0060] Corrosion inhibitor adsorption: Select environmentally friendly phytic acid as the corrosion inhibitor, prepare 1wt% phytic acid solution, put the nano-composite fiber into a sealed container, use spray adsorption method to make the phytic acid solution evenly adhere to the surface of the fiber to obtain composite steel fiber, dry at 40℃ for 2h, form a corrosion protection film, effectively resist salt and alkali, marine environment erosion;

[0061] Plant fiber mixing: The waste wood fiber is crushed and ground into plant fiber powder with an average particle size of 1μm; the powder is mixed with the composite steel fiber at a mass ratio of 1:3 in a blender, stirred at 200r / min for 5min, the plant fiber powder is filled in the steel fiber surface and gap to form an interlocking structure, further improve the strength and toughness of the fiber, realize the resource utilization of waste, and obtain modified steel fiber;

[0062] S2: Raw material pretreatment;

[0063] Drying the ferrite aluminate cement, fine aggregate and coarse aggregate at 40℃ for 2h;

[0064] S3: Weighing raw materials;

[0065] Ferrite aluminate cement 40 parts, as the main cementitious material, has good corrosion resistance, is the key to ensure the performance stability of the formwork in harsh environment, ferrite aluminate cement is made of proper proportion of iron ore, bauxite, limestone and other raw materials by high temperature calcination, main mineral components include anhydrous calcium sulphoaluminate, dicalcium silicate and ferrite calcium aluminate, etc;

[0066] Aggregate 80 parts, fine aggregate (quartz sand) and coarse aggregate (broken stone) mass ratio 30:50, aggregate provides skeleton support for the formwork, enhances the strength and stability of the formwork, fine aggregate particle size 0.15mm, coarse aggregate particle size 5mm;

[0067] Modified steel fiber 2 parts, diameter 10μm, length 6mm, uniformly dispersed in the cement matrix, can effectively prevent the generation and expansion of cracks, improve the toughness and impact resistance of the formwork;

[0068] Admixture 1 part; water reducing agent (Sika ViscoCrete-1000), viscosity reducing agent and waterproof agent (organic silicon waterproof agent) mass ratio 0.5:0.5:1;

[0069] Water 13 parts;

[0070] S4: Mixing and stirring;

[0071] After drying, the fine aggregate and the coarse aggregate are added into a forced mixer, and dry mixing is performed at a rotating speed of 100 r / min for 0.5 min to uniformly mix the fine aggregate and the coarse aggregate; then, the ferrum aluminate cement is added, and dry mixing is continued at the same rotating speed for 1 min; water, a water reducing agent, a viscosity reducing agent, and a waterproof agent are added, the rotating speed of the mixer is increased to 200 r / min, and wet mixing is performed for 1 min; the modified steel fiber is added into the mixer in two times with an interval of 2 min, and continuous mixing is performed at a rotating speed of 150 r / min for 10 min to obtain a concrete mixture;

[0072] S5: template forming;

[0073] A layer of water-based release agent is evenly applied on the bottom and the periphery of the mold, the thickness of the water-based release agent is controlled to be 0.1 mm, the mixed concrete mixture is poured into the mold at one time until the designed thickness of the template is reached, the mold is vibrated using a vibrating table, the vibration frequency of the vibrating table is set to 20 Hz, and the vibrating time is 1 min, so that the cement slurry fully fills the mold, expels the internal bubbles, and ensures the compactness of the template;

[0074] S6: the ferrum aluminate cement-based high corrosion-resistant and demolding-free template is obtained after curing;

[0075] After demolding, the template is placed in a curing room with a temperature of 20 ℃ and a relative humidity of ≥95% for curing for 3 days, in the initial curing stage, a plastic film is covered on the surface of the template, the adhesion of the film to the surface of the template is ≥90%, during the curing process, the template is checked every 6 h to observe whether cracks, deformation, or the like occur, if the surface is found to be dry, water is supplemented in time by spraying, and the spraying pressure is controlled to be 0.5 MPa.

[0076] Embodiment 3: The embodiment provides a preparation method of a ferrum aluminate cement-based high corrosion-resistant and demolding-free template, comprising the following steps:

[0077] S1: steel fiber modification;

[0078] Plasma surface activation: the steel fiber is placed in a low-temperature plasma device, air / argon mixed gas with a volume ratio of 1.2:1 is introduced, the treatment power is set to 50 W, and the treatment time is 4 min;

[0079] Nano-silica spraying composite: 40 nm nano-silica and 3 wt% polyvinyl alcohol aqueous solution are mixed, ultrasonic dispersion is performed at 210 W for 24 min to prepare a uniform spraying liquid; the spraying liquid is sprayed on the surface of the activated fiber at a pressure of 0.5 MPa by using an air spraying device, and drying is performed at 53 ℃ for 2 h;

[0080] Corrosion inhibitor adsorption: Select environmentally friendly phytic acid as the corrosion inhibitor, prepare a 1.8wt% phytic acid solution, place the nano-composite fiber in a sealed container, and use a spray adsorption method to evenly attach the phytic acid solution to the surface of the fiber to obtain a composite steel fiber. Dry at 46°C for 2h to form a corrosion protection film, effectively resisting salt and alkali, and marine environment erosion;

[0081] Plant fiber mixing: The waste bamboo fiber is crushed and ground into plant fiber powder with an average particle size of 3μm; the powder is mixed with the composite steel fiber at a mass ratio of 1:4 in a blender, and stirred at 320r / min for 8min to fill the plant fiber powder into the steel fiber surface and gap to form an interlocking structure, further improving the strength and toughness of the fiber, and realizing the resource utilization of waste, obtaining modified steel fiber;

[0082] S2: Raw material pretreatment;

[0083] Drying the ferrite aluminate cement, fine aggregate, and coarse aggregate at 52°C for 3h;

[0084] S3: Weighing raw materials;

[0085] Ferrite aluminate cement 54 parts, as the main cementitious material, has good corrosion resistance, is the key to ensure the performance stability of the formwork in harsh environments, and is made of proper proportions of iron ore, bauxite, limestone and other raw materials by high temperature calcination. The main mineral components include anhydrous calcium sulphoaluminate, dicalcium silicate and ferrite aluminate calcium, etc.

[0086] Aggregate 98 parts, fine aggregate (quartz sand) and coarse aggregate (broken stone) mass ratio 38:60, aggregate provides skeleton support for the formwork, enhances the strength and stability of the formwork, fine aggregate particle size 0.4mm, coarse aggregate particle size 10mm;

[0087] Modified steel fiber 4 parts, diameter 20μm, length 10mm, uniformly dispersed in the cement matrix, can effectively prevent the generation and expansion of cracks, and improve the toughness and impact resistance of the formwork;

[0088] Admixtures 2 parts; water reducing agent (Sika ViscoCrete-1000), viscosity reducing agent and waterproof agent (organic silicon waterproof agent) mass ratio 1:1:2;

[0089] Water 16 parts;

[0090] S4: Mixing and stirring;

[0091] The dry fine aggregate and coarse aggregate are added into a forced stirrer, and dry mixing is performed at a rotating speed of 180 r / min for 1 min to uniformly mix the coarse and fine aggregates; then ferrum aluminate cement is added, and dry mixing is continued at the same rotating speed for 2 min; water, water reducing agent, viscosity reducing agent and waterproof agent are added, the rotating speed of the stirrer is increased to 260 r / min, and wet mixing is performed for 2 min; the modified steel fiber is added into the stirrer in three times with an interval of 2 min each time, and continuous stirring is performed at a rotating speed of 220 r / min for 12 min to obtain a concrete mixture;

[0092] S5: template forming;

[0093] A layer of water-based release agent is evenly applied on the bottom and four sides of the mold, and the thickness of the water-based release agent is controlled to be 0.2 mm. The stirred concrete mixture is poured into the mold at one time until the designed thickness of the template is reached. A vibrating table is used to vibrate the mold, the vibration frequency of the vibrating table is set to 40 Hz, and the vibration time is 3 min. The cement slurry is fully filled in the mold to expel the internal bubbles and ensure the compactness of the template.

[0094] S6: ferrum aluminate cement-based high corrosion-resistant and demoulding-free template obtained after standing and curing;

[0095] After forming, the template is demoulded after standing for 11 h, and then placed in a curing room with a temperature of 28 ℃ and a relative humidity of ≥95% for 7 days of curing. In the initial stage of curing, a plastic film is covered on the surface of the template, and the adhesion of the film to the surface of the template is ≥90%. During the curing process, the template is checked every 6 h to observe whether there are cracks, deformation and other conditions. If the surface is dry, water is supplemented in time by spraying, and the spraying pressure is controlled to be 0.5 MPa.

[0096] Comparative Example 1: The difference between this comparative example and Example 3 is that the steel fiber is not subjected to nano-silica spraying and compounding.

[0097] Comparative Example 2: The difference between this comparative example and Example 3 is that the steel fiber is not subjected to corrosion inhibitor adsorption.

[0098] Comparative Example 3: The difference between this comparative example and Example 3 is that neither the steel fiber is subjected to nano-silica spraying and compounding nor the steel fiber is subjected to corrosion inhibitor adsorption.

[0099] Experimental Example: 1. The toughness index I5 is tested according to the ASTM C1550 index.

[0100] 2. The impact resistance number is tested according to the ACI 544.2R index.

[0101] 3. After the template sample is corroded in a 5% NaCl salt spray chamber (35 ℃) for 1000 h, the toughness index I5 and the impact resistance number are tested again.

[0102] The results are shown in the following table:

[0103]

[0104] From the above table, by spraying nano-silica on the steel fiber, the impact resistance of the template is improved; by adsorbing the corrosion inhibitor on the steel fiber, the corrosion resistance of the template is significantly improved; after compounding the two, not only the impact resistance and corrosion resistance are improved, but also the toughness is unexpectedly enhanced.

[0105] The above examples are only used to illustrate the technical solutions of the present application, but not limit it; although the present application has been described in detail with reference to the foregoing examples, those skilled in the art should understand that the technical solutions recorded in the foregoing examples can be modified, or some technical features can be replaced by equivalents; and these modifications or replacements will not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A high corrosion-resistant, non-removable formwork based on aluminoferrite cement, characterized in that, Includes the following components: 40-60 parts of aluminoferrite cement; 80-100 parts of aggregate, wherein the aggregate consists of fine aggregate with a particle size of 0.15-0.6 mm and coarse aggregate with a particle size of 5-10 mm in a mass ratio of 30-40:50-70; 2-5 parts of modified steel fiber, wherein the modified steel fiber is obtained by plasma surface activation of steel fiber, nano-silica spraying and composite, corrosion inhibitor adsorption and mixing with plant fiber; 1-3 parts of admixture; the admixture is composed of a water-reducing agent, a viscosity-reducing agent and a waterproofing agent in a mass ratio of 0.5-2:0.5-1.5:1-3; 13-20 parts water.

2. A method for preparing a high corrosion-resistant, non-removable formwork based on aluminoferrite cement as described in claim 1, characterized in that, Includes the following steps: S1: Steel fiber modified; Plasma surface activation: Place the steel fiber in a low-temperature plasma device and treat it with an air / argon mixed gas for 2-5 minutes. Nano-silica spray coating: Nano-silica is mixed with a polyvinyl alcohol aqueous solution, ultrasonically dispersed, and a uniform spray coating is prepared. Using an air spraying device, the spraying liquid is sprayed onto the surface of the activated fiber; Corrosion inhibitor adsorption: Prepare a phytic acid aqueous solution, and use spray adsorption to make the phytic acid aqueous solution evenly adhere to the fiber surface to obtain composite steel fibers, which are then dried to form a corrosion-inhibiting protective film. Plant fiber blending: Waste bamboo or wood fiber is crushed and ground into plant fiber powder; the powder is mixed with composite steel fiber in a mixer to obtain modified steel fiber; S2: Raw material pretreatment; Dry the aluminoferrite cement, fine aggregate, and coarse aggregate at 40-60℃ for 2-4 hours; S3: Mixing and stirring; Dry the dried fine and coarse aggregates in a forced mixer and mix them dry; add aluminoferrite cement and continue mixing dry; add water, water-reducing agent, viscosity reducer and waterproofing agent and mix wet; add modified steel fibers in batches to the mixer and continue mixing to obtain concrete mixture; S4: Template forming; Pour the well-mixed concrete mixture into the mold at once, and use a vibrating table to compact the mold. S5: After static curing, high corrosion-resistant, non-removable formwork based on aluminate cement is obtained.

3. The method for preparing the high corrosion-resistant, non-removable formwork based on aluminoferrite cement according to claim 2, characterized in that, The specific steps of the nano-silica spraying composite process are as follows: mix nano-silica with a particle size of 20-50nm with 2-5wt% polyvinyl alcohol aqueous solution, and ultrasonically disperse at 150-250W for 15-30min to prepare a uniform spraying solution. Using an air spraying device, the spraying liquid is sprayed onto the activated fiber surface at a pressure of 0.3-0.6 MPa, and then dried at 50-60℃ for 1-2 hours.

4. The method for preparing the high corrosion-resistant, non-removable formwork based on aluminoferrite cement according to claim 2, characterized in that, The specific steps for corrosion inhibitor adsorption are as follows: prepare a 1-2 wt% phytic acid aqueous solution, place the nanocomposite fiber in a sealed container, and use spray adsorption to make the phytic acid aqueous solution uniformly adhere to the fiber surface to obtain composite steel fiber. Dry at 40-50℃ for 2-3 hours to form a corrosion-inhibiting protective film.

5. The method for preparing the high corrosion-resistant, non-removable formwork based on aluminoferrite cement according to claim 2, characterized in that, The specific steps for mixing plant fibers are as follows: waste bamboo or wood fibers are crushed and ground into plant fiber powder with an average particle size of 1-5 μm; the powder is mixed with composite steel fibers in a mixer at a mass ratio of 1:3-5 and stirred at 200-350 r / min for 5-10 min to obtain modified steel fibers.

6. The method for preparing the high corrosion-resistant, non-removable formwork based on aluminoferrite cement according to claim 2, characterized in that, S3 specifically involves: adding the dried fine and coarse aggregates to a forced mixer and dry-mixing at 100-200 r / min for 0.5-1 min to ensure uniform mixing; adding aluminoferrite cement and continuing dry-mixing at the same speed for 1-2 min; adding water, water-reducing agent, viscosity reducer, and waterproofing agent, and increasing the mixer speed to 200-300 r / min for wet mixing for 1-2 min; adding modified steel fibers to the mixer in 2-3 batches, with an interval of 2-3 min between each batch, and continuously mixing at 150-250 r / min for 10-15 min to obtain the concrete mixture.

7. The method for preparing the high corrosion-resistant, non-removable formwork based on aluminoferrite cement according to claim 2, characterized in that, S4 specifically involves: applying a layer of water-based release agent evenly to the bottom and sides of the mold, with the thickness of the water-based release agent controlled at 0.1-0.3mm; pouring the mixed concrete mixture into the mold at once; and using a vibrating table to vibrate the mold, with the vibration frequency of the vibrating table set to 20-50Hz and the vibration time being 1-3 minutes.

8. The method for preparing the high corrosion-resistant, non-removable formwork based on aluminoferrite cement according to claim 2, characterized in that, S5 specifically refers to: after molding, let it stand for 10-12 hours before demolding, and then place the mold in a temperature of 20-30℃ and a relative humidity of ≥95% for 3-7 days for curing.

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