Iron aluminate cement-based high-corrosion-resistance non-dismantling formwork and preparation method thereof

Abstract

The invention discloses an aluminoferrite cement-based high-corrosion-resistance non-dismantling formwork and a preparation method thereof, and belongs to the technical field of aluminoferrite cement, the aluminoferrite cement-based high-corrosion-resistance non-dismantling formwork comprises 40-60 parts of aluminoferrite cement, 80-100 parts of aggregate, 2-5 parts of modified steel fiber, 1-3 parts of additive and 13-20 parts of water. After the steel fibers are subjected to nano silicon dioxide spraying and compounding, the impact resistance of the template is remarkably improved. And corrosion inhibitor adsorption treatment is carried out on the steel fibers, so that the corrosion resistance of the template is greatly improved. After the two treatment modes of nano silicon dioxide spraying compounding and corrosion inhibitor adsorption are compounded, the synergistic interaction effect is achieved in the aspect of improving the impact resistance and the corrosion resistance, and the toughness of the template is accidentally enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of ferroaluminate cement, and in particular to a ferroaluminate cement-based highly corrosion-resistant, non-disassembly formwork and a preparation method thereof. Background Art

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

[0003] Due to the properties of Portland cement's hydration products, corrosive ions from the outside world enter the concrete structure in marine and saline-alkali environments. This, on the one hand, corrosively damages the concrete's hydration products, eliminating its protective effect on the steel bars. On the other hand, the steel bars, exposed to the corrosive ions, rust and expand, further exacerbating concrete damage, thereby compromising the durability and service life of structures like cross-sea bridges. Corrosion damage to concrete structures in marine engineering and saline-alkali areas has become a global engineering challenge. To improve the corrosion resistance of concrete in harsh environments, anti-corrosion coatings are typically applied to areas in contact with corrosive media. However, due to the mismatch between the durability and thermal expansion coefficient of the anti-corrosion coatings themselves and the concrete, they typically need to be reapplied every 5-10 years, failing to fundamentally address corrosion damage.

[0004] Ferroaluminate cement, as a new cement material, possesses unique performance advantages. Compared to traditional Portland cement, ferroaluminate cement belongs to a different mineral system and represents a revolutionary breakthrough in cement technology. Extensive data demonstrates that ferroaluminate cement possesses the unique property of being non-corrosive to seawater, saline-alkali, and alkaline environments. However, since its price is 2-3 times that of ordinary Portland cement, its extensive use in harsh environments such as those involving seawater and saline-alkali environments significantly increases construction costs. Removable formwork is a new technology that has emerged in recent years. This technology combines ferroaluminate cement technology with removable formwork technology, allowing this removable formwork to directly contact the external corrosive environment while isolating the concrete within. This achieves both improved durability and significant cost reductions.

[0005] Based on this, the present invention designs a ferroaluminate cement-based highly corrosion-resistant and disassembly-free formwork and a preparation method thereof to solve the above problems. Summary of the Invention

[0006] In view of the above shortcomings of the prior art, the present invention provides a ferroaluminate cement-based highly corrosion-resistant non-disassembly formwork, comprising the following components:

[0007] 40-60 parts of ferroaluminate cement;

[0008] 80-100 parts of aggregate, wherein the aggregate is composed 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;

[0009] 2-5 parts of modified steel fiber, wherein the modified steel fiber is obtained by plasma surface activation, nano-silicon dioxide spraying and compounding, corrosion inhibitor adsorption and mixing with plant fiber;

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

[0011] 13-20 parts water.

[0012] A method for preparing the ferroaluminate cement-based highly corrosion-resistant, non-disassembly formwork comprises the following steps:

[0013] S1: steel fiber modification;

[0014] Plasma surface activation: Place the steel fiber in a low-temperature plasma device and introduce air / argon mixed gas for 2-5 minutes;

[0015] Nano-silica spray compounding: Mix nano-silica with polyvinyl alcohol aqueous solution, ultrasonically disperse, and prepare a uniform spray liquid; use air spray equipment to spray the spray liquid on the activated fiber surface;

[0016] Corrosion inhibitor adsorption: prepare phytic acid aqueous solution, and use spray adsorption method to make the phytic acid aqueous solution evenly adhere to the fiber surface to obtain composite steel fiber, and dry it to form a corrosion inhibition protective film;

[0017] Plant fiber mixing: crush and grind discarded bamboo fiber or wood fiber to make plant fiber powder; mix the powder with composite steel fiber in a blender and stir to obtain modified steel fiber;

[0018] S2: raw material pretreatment;

[0019] Dry the ferroaluminate cement, fine aggregate and coarse aggregate at 40-60℃ for 2-4h;

[0020] S3: Mixing and stirring;

[0021] Add the dried fine aggregate and coarse aggregate into a forced mixer and dry mix; add ferroaluminate cement and continue dry mixing; add water, water reducer, viscosity reducer and waterproofing agent and wet mix; add modified steel fiber into the mixer in batches and continue stirring to obtain a concrete mixture;

[0022] S4: template forming;

[0023] Pour the mixed concrete mixture into the mold at one time and vibrate the mold using a vibrating table;

[0024] S5: After standing still and curing, a ferroaluminate cement-based highly corrosion-resistant, non-dismantling formwork is obtained.

[0025] Furthermore, the nano-silica spray compounding step is specifically as follows: nano-silica with a particle size of 20-50 nm is mixed with a 2-5 wt% polyvinyl alcohol aqueous solution, and ultrasonically dispersed at 150-250 W for 15-30 minutes to prepare a uniform spray liquid; using air spray equipment, the spray liquid is sprayed on the activated fiber surface at a pressure of 0.3-0.6 MPa, and dried at 50-60°C for 1-2 hours.

[0026] Furthermore, the specific steps of corrosion inhibitor adsorption are: preparing a 1-2wt% phytic acid aqueous solution, placing the nano-composite fiber in a closed container, using spray adsorption to make the phytic acid aqueous solution evenly adhere to the fiber surface to obtain composite steel fiber, and drying at 40-50°C for 2-3h to form a corrosion inhibitor protective film.

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

[0028] Furthermore, S3 is specifically as follows: 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 evenly mix the coarse and fine aggregates; adding ferroaluminate cement, and continuing dry mixing at the same speed for 1-2 min; adding water, a water reducer, a viscosity reducer and a waterproofing agent, increasing the mixer speed 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 minutes each time, and continuously stirring at a speed of 150-250 r / min for 10-15 min to obtain a concrete mixture.

[0029] Furthermore, S4 is specifically as follows: evenly apply a layer of water-based release agent on the bottom and around the mold, the thickness of the water-based release agent is controlled at 0.1-0.3mm, pour the mixed concrete mixture into the mold at one time, and vibrate the mold using a vibration table. The vibration frequency of the vibration table is set to 20-50Hz, and the vibration time is 1-3min.

[0030] Furthermore, S5 is specifically as follows: after forming, the mold is removed after standing for 10-12 hours, and then the template is placed at a temperature of 20-30°C and a relative humidity of ≥95% for 3-7 days of curing.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] 1. After the steel fibers are sprayed and compounded with nano-silicon dioxide, the impact resistance of the template is significantly improved. Nano-silicon dioxide has the characteristics of small particle size, many micropores, and a large specific surface area. When it is sprayed on the surface of the steel fibers, these characteristics play an important role. On the one hand, the nano-silicon dioxide particles form a tight bond with the steel fibers, enhancing the surface strength of the fibers. Since the nano-silicon dioxide particles have a large specific surface area and a strong interfacial bonding effect with the fiber matrix, they can absorb a large amount of impact energy, just like building an energy buffer layer on the fiber surface. When impacted, this buffer layer can effectively disperse the impact energy and prevent cracks from being generated and expanding inside the fibers. On the other hand, the filling effect of nano-silicon dioxide makes the microstructure of the fibers more compact. Its small particle size can fill the gaps and defects of the steel fibers, reducing stress concentration points, thereby further improving the impact resistance of the fibers and even the entire template. This effect is similar to filling tiny gaps in building structures to enhance the stability of the overall structure, so that the formwork can better maintain structural integrity when facing external force impact, effectively avoiding cracking or damage caused by impact.

[0033] 2. The present invention greatly improves the corrosion resistance of the template by subjecting the steel fiber to corrosion inhibitor adsorption treatment. The present invention uses environmentally friendly phytic acid as a corrosion inhibitor, and the phytic acid molecular structure contains multiple active groups. When the phytic acid aqueous solution is evenly attached to the fiber surface by spray adsorption and dried, it will undergo a series of physical and chemical reactions with 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 fiber surface, which enables the phytic acid to be tightly adsorbed on the fiber surface. From a chemical perspective, the active groups in the phytic acid molecules may react chemically with certain atoms or groups on the fiber surface to form chemical bonds, further enhancing the stability of the adsorption. In this way, a dense corrosion-inhibiting protective film is formed on the fiber surface. In harsh corrosive environments such as saline-alkali and oceans, this protective film can effectively prevent corrosive media, such as chloride ions, sulfate ions, hydroxide ions, etc., from directly contacting the fiber. At the same time, phytic acid corrosion inhibitors may also inhibit electrochemical reactions during the corrosion process by changing the charge state and interface properties of the metal surface, thereby significantly improving the corrosion resistance of the template in these harsh environments and extending the service life of the template.

[0034] 3. The combination of nano-silica spraying and corrosion inhibitor adsorption not only synergistically enhances impact and corrosion resistance but also unexpectedly increases the toughness of the formwork. While enhancing impact resistance, the nano-silica's tight bond with the steel fibers and its densification of the microstructure provide a better foundation for the adhesion of the corrosion inhibitor film, allowing the inhibitor to more stably reside on the fiber surface and enhancing corrosion inhibition. The presence of the corrosion inhibitor film reduces environmental erosion on the fibers, ensuring the stability of the fibers' inherent properties and, in turn, contributing to improved formwork toughness. Furthermore, the combined action of nano-silica and corrosion inhibitor may alter the molecular chain arrangement and interaction within the steel fibers, enhancing the sliding and coordinated deformation capabilities of the molecular chains. When subjected to external forces, the molecular chains are able to better coordinate deformation and absorb energy, resulting in higher toughness. This comprehensive performance improvement enables ferroaluminate cement-based, highly corrosion-resistant, non-dismantling formwork to demonstrate excellent performance in a variety of complex environments, promising broad application prospects. DETAILED DESCRIPTION

[0035] To make the purpose, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in 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 part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0036] Example 1: This example provides a method for preparing a ferroaluminate cement-based highly corrosion-resistant, non-disassembly formwork, comprising the following steps:

[0037] S1: steel fiber modification;

[0038] Plasma surface activation: The steel fiber was placed in a low-temperature plasma device and a mixed gas of air and argon with a volume ratio of 2:1 was introduced. The treatment power was set to 80W and the treatment time was 5 minutes.

[0039] Nano-silica spray compounding: Nano-silica with a particle size of 50 nm was mixed with a 5 wt% aqueous solution of polyvinyl alcohol and ultrasonically dispersed at 250 W for 30 minutes to prepare a uniform spray solution. The spray solution was sprayed onto the activated fiber surface at a pressure of 0.6 MPa using an air spray device and dried at 60°C for 2 hours.

[0040] Corrosion inhibitor adsorption: Environmentally friendly phytic acid is used as the corrosion inhibitor. A 2wt% phytic acid aqueous solution is prepared. The nano-composite fiber is placed in a sealed container. The phytic acid aqueous solution is evenly attached to the fiber surface by spray adsorption to obtain composite steel fiber. The fiber is dried at 50°C for 3 hours to form a corrosion inhibition protective film that effectively resists erosion in saline and alkaline environments and marine environments.

[0041] Plant fiber mixing: Discarded wood fibers are crushed and ground into plant fiber powder with an average particle size of 5 μm. This powder is mixed with composite steel fibers in a blender at a mass ratio of 1:5 and stirred at 350 rpm for 10 minutes to allow the plant fiber powder to fill the surface and gaps of the steel fibers, forming an interlocking structure, further improving the strength and toughness of the fibers while realizing waste resource utilization to obtain modified steel fibers.

[0042] S2: raw material pretreatment;

[0043] The ferroaluminate cement, fine aggregate and coarse aggregate were dried at 60°C for 4 h;

[0044] S3: weigh the raw materials;

[0045] 60 parts of ferroaluminate cement, as the main cementing material, has good corrosion resistance and is the key to ensuring the stable performance of the formwork in harsh environments. Ferroaluminate cement is made by calcining raw materials such as iron ore, bauxite, and limestone in appropriate proportions at high temperatures. The main mineral components include anhydrous calcium sulfoaluminate, dicalcium silicate, and calcium aluminoferrite;

[0046] 100 parts of aggregate, with a mass ratio of fine aggregate (quartz sand) to coarse aggregate (crushed stone) of 40:70. Aggregates provide skeleton support for the formwork, enhancing the strength and stability of the formwork. The particle size of fine aggregate is 0.6mm, and the particle size of coarse aggregate is 20mm.

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

[0048] 3 parts of admixture; the mass ratio of water reducer (Sika ViscoCrete-1000), viscosity reducer and waterproofing agent (silicone waterproofing agent) is 2:1.5:3;

[0049] 20 parts water;

[0050] S4: mixing and stirring;

[0051] The dried fine aggregate and coarse aggregate were added to a forced mixer and dry-mixed at a speed of 200 r / min for 1 minute to uniformly mix the coarse and fine aggregates; ferroaluminate cement was then added and dry-mixed at the same speed for 2 minutes; water, a water reducer, a viscosity reducer, and a waterproofing agent were added, the mixer speed was increased to 300 r / min, and wet-mixed for 2 minutes; the modified steel fiber was added to the mixer in three batches, with an interval of 3 minutes between each addition, and the mixture was stirred at a speed of 250 r / min for 15 minutes to obtain a concrete mixture;

[0052] S5: template forming;

[0053] Apply a layer of water-based release agent evenly on the bottom and around the mold. The thickness of the water-based release agent should be controlled at 0.3mm. Pour the mixed concrete mixture into the mold at one time until it reaches the designed thickness of the template. Use a vibration table to vibrate the mold. The vibration frequency of the vibration table is set to 50Hz and the vibration time is 3 minutes. Ensure that the cement slurry fully fills the mold, expel internal bubbles, and ensure the density of the template.

[0054] S6: After standing still and curing, a ferroaluminate cement-based highly corrosion-resistant, non-dismantling formwork is obtained;

[0055] After forming, let it stand for 12 hours before demoulding, and then place the template in a curing room with a temperature of 30℃ and a relative humidity of ≥95% for 7 days of curing. In the initial stage of curing, the surface of the template is covered with a plastic film, and the degree of adhesion between the film and the template surface is ≥90%. During the curing process, the template is checked every 6 hours to observe whether there are cracks, deformations, etc. If the surface is found to be dry, it is promptly replenished with moisture by spraying, and the spray pressure is controlled at 0.5MPa.

[0056] Example 2: This example provides a method for preparing a ferroaluminate cement-based highly corrosion-resistant, non-disassembly formwork, comprising the following steps:

[0057] S1: steel fiber modification;

[0058] Plasma surface activation: The steel fiber was placed in a low-temperature plasma device and a mixture of air and argon with a volume ratio of 1:1 was introduced. The treatment power was set to 30W and the treatment time was 2 minutes.

[0059] Nano-silica spray compounding: Nano-silica with a particle size of 20 nm was mixed with a 2 wt% aqueous solution of polyvinyl alcohol and ultrasonically dispersed at 150 W for 15 minutes to prepare a uniform spray solution. The spray solution was sprayed onto the activated fiber surface at a pressure of 0.3 MPa using an air spray device and dried at 50°C for 1 hour.

[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] The dried fine aggregate and coarse aggregate were added to a forced mixer and dry-mixed at a speed of 100 r / min for 0.5 min to uniformly mix the coarse and fine aggregates; ferroaluminate cement was then added and dry-mixed at the same speed for 1 min; water, a water reducer, a viscosity reducer, and a waterproofing agent were added, the mixer speed was increased to 200 r / min, and wet-mixed for 1 min; the modified steel fiber was added to the mixer in two batches, with an interval of 2 min between each additions, and the mixture was stirred at a speed of 150 r / min for 10 min to obtain a concrete mixture;

[0072] S5: template forming;

[0073] Apply a layer of water-based release agent evenly on the bottom and around the mold. The thickness of the water-based release agent should be controlled at 0.1mm. Pour the mixed concrete mixture into the mold at one time until it reaches the designed thickness of the template. Use a vibration table to vibrate the mold. The vibration frequency of the vibration table is set to 20Hz and the vibration time is 1 minute. Ensure that the cement slurry fully fills the mold, expel internal bubbles, and ensure the density of the template.

[0074] S6: After standing still and curing, a ferroaluminate cement-based highly corrosion-resistant, non-dismantling formwork is obtained;

[0075] After forming, let it stand for 10 hours before demoulding, and then place the template in a curing room with a temperature of 20℃ and a relative humidity of ≥95% for 3 days of curing. In the initial stage of curing, the surface of the template is covered with a plastic film, and the degree of adhesion between the film and the template surface is ≥90%. During the curing process, the template is checked every 6 hours to observe whether there are cracks, deformations, etc. If the surface is found to be dry, it is promptly replenished with moisture by spraying, and the spray pressure is controlled at 0.5MPa.

[0076] Example 3: This example provides a method for preparing a ferroaluminate cement-based highly corrosion-resistant, non-disassembly formwork, comprising the following steps:

[0077] S1: steel fiber modification;

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

[0079] Nano-silica spray compounding: Nano-silica with a particle size of 40 nm was mixed with a 3 wt% aqueous solution of polyvinyl alcohol and ultrasonically dispersed at 210 W for 24 minutes to prepare a uniform spray solution. The spray solution was sprayed onto the activated fiber surface at a pressure of 0.5 MPa using an air spray device and dried at 53°C for 2 hours.

[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 into 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] It can be seen from the above table that the impact resistance of the template is improved by spraying and compounding the steel fibers with nano-silica; the corrosion resistance of the template is significantly improved by adsorbing corrosion inhibitors on the steel fibers; after the two are compounded, not only the impact resistance and corrosion resistance are improved, but also the toughness is unexpectedly enhanced.

[0105] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements will not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A ferroaluminate cement-based highly corrosion-resistant non-disassembly formwork, characterized in that: Includes the following components: 40-60 parts of ferroaluminate cement; 80-100 parts of aggregate, wherein the aggregate is composed 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, nano-silicon dioxide spraying and compounding, corrosion inhibitor adsorption and mixing with plant fiber; 1-3 parts of admixture; the admixture is composed of a water reducer, a viscosity reducer 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 the ferroaluminate cement-based highly corrosion-resistant and non-disassembly formwork according to claim 1, characterized in that: The following steps are involved: S1: steel fiber modification; Plasma surface activation: Place the steel fiber in a low-temperature plasma device and introduce air / argon mixed gas for 2-5 minutes; Nano-silica spray compounding: Mix nano-silica with polyvinyl alcohol aqueous solution, ultrasonically disperse, and prepare a uniform spray solution; Using air spraying equipment, spray the spray liquid on the activated fiber surface; Corrosion inhibitor adsorption: prepare phytic acid aqueous solution, and use spray adsorption method to make the phytic acid aqueous solution evenly adhere to the fiber surface to obtain composite steel fiber, and dry it to form a corrosion inhibition protective film; Plant fiber mixing: crush and grind discarded bamboo fiber or wood fiber to make plant fiber powder; mix the powder with composite steel fiber in a blender and stir to obtain modified steel fiber; S2: raw material pretreatment; Dry the ferroaluminate cement, fine aggregate and coarse aggregate at 40-60℃ for 2-4h; S3: Mixing and stirring; Add the dried fine aggregate and coarse aggregate into a forced mixer and dry mix; add ferroaluminate cement and continue dry mixing; add water, water reducer, viscosity reducer and waterproofing agent and wet mix; add modified steel fiber into the mixer in batches and continue stirring to obtain a concrete mixture; S4: template forming; Pour the mixed concrete mixture into the mold at one time and vibrate the mold using a vibrating table; S5: After standing still and curing, a ferroaluminate cement-based highly corrosion-resistant, non-dismantling formwork is obtained.

3. The method for preparing the ferroaluminate cement-based highly corrosion-resistant and disassembly-free formwork according to claim 2, characterized in that: The nano-silica spray compounding step is specifically as follows: mixing nano-silica with a particle size of 20-50 nm with a 2-5 wt% polyvinyl alcohol aqueous solution, and ultrasonically dispersing at 150-250 W for 15-30 min to prepare a uniform spray solution; The spraying liquid is sprayed on the activated fiber surface at a pressure of 0.3-0.6 MPa using air spray equipment, and dried at 50-60° C. for 1-2 hours.

4. The method for preparing the ferroaluminate cement-based highly corrosion-resistant and non-disassembly formwork according to claim 2, characterized in that: The specific steps of corrosion inhibitor adsorption are: preparing a 1-2wt% phytic acid aqueous solution, placing the nano-composite fiber in a closed container, using spray adsorption to make the phytic acid aqueous solution evenly adhere to the fiber surface to obtain composite steel fiber, and drying at 40-50°C for 2-3h to form a corrosion inhibitor protective film.

5. The method for preparing the ferroaluminate cement-based highly corrosion-resistant and non-disassembly formwork according to claim 2, characterized in that: The specific steps of plant fiber mixing are: crushing and grinding discarded bamboo fiber or wood fiber to prepare plant fiber powder with an average particle size of 1-5 μm; mixing the powder with composite steel fiber in a blender at a mass ratio of 1:3-5, stirring at 200-350 r / min for 5-10 minutes to obtain modified steel fiber.

6. The method for preparing the ferroaluminate cement-based highly corrosion-resistant and non-disassembly formwork according to claim 2, characterized in that: S3 specifically comprises the following steps: adding 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 uniformly mix the coarse and fine aggregates; adding ferroaluminate cement, and continuing dry-mixing at the same speed for 1-2 min; adding water, a water reducer, a viscosity reducer, and a waterproofing agent, increasing the mixer speed to 200-300 r / min, and wet-mixing for 1-2 min; adding 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.

7. The method for preparing the ferroaluminate cement-based highly corrosion-resistant and non-disassembly formwork according to claim 2, characterized in that: S4 is specifically as follows: evenly apply a layer of water-based release agent on the bottom and around the mold. The thickness of the water-based release agent is controlled at 0.1-0.3mm. Pour the mixed concrete mixture into the mold at one time. Use a vibration table to vibrate the mold. The vibration frequency of the vibration table is set to 20-50Hz, and the vibration time is 1-3min.

8. The method for preparing the ferroaluminate cement-based highly corrosion-resistant and non-disassembly formwork according to claim 2, characterized in that: S5 is specifically as follows: after forming, let it stand for 10-12 hours before demoulding, and place the template at a temperature of 20-30℃ and a relative humidity of ≥95% for 3-7 days of curing.

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