CN115959873B - High-ductility concrete with high bending toughness and preparation method thereof - Google Patents
High-ductility concrete with high bending toughness and preparation method thereof Download PDFInfo
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- 239000004567 concrete Substances 0.000 title claims abstract description 52
- 238000005452 bending Methods 0.000 title claims abstract description 17
- 238000002360 preparation method Methods 0.000 title abstract description 7
- 239000000835 fiber Substances 0.000 claims abstract description 120
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 68
- 239000010959 steel Substances 0.000 claims abstract description 68
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims abstract description 40
- 239000003513 alkali Substances 0.000 claims abstract description 23
- 239000012783 reinforcing fiber Substances 0.000 claims abstract description 13
- 239000010881 fly ash Substances 0.000 claims abstract description 10
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- XHXFXVLFKHQFAL-UHFFFAOYSA-N phosphoryl trichloride Chemical compound ClP(Cl)(Cl)=O XHXFXVLFKHQFAL-UHFFFAOYSA-N 0.000 claims description 28
- ZCCIPPOKBCJFDN-UHFFFAOYSA-N calcium nitrate Chemical compound [Ca+2].[O-][N+]([O-])=O.[O-][N+]([O-])=O ZCCIPPOKBCJFDN-UHFFFAOYSA-N 0.000 claims description 24
- 239000002738 chelating agent Substances 0.000 claims description 23
- 229910000029 sodium carbonate Inorganic materials 0.000 claims description 20
- 238000003756 stirring Methods 0.000 claims description 19
- YLQBMQCUIZJEEH-UHFFFAOYSA-N tetrahydrofuran Natural products C=1C=COC=1 YLQBMQCUIZJEEH-UHFFFAOYSA-N 0.000 claims description 18
- 238000002156 mixing Methods 0.000 claims description 17
- 239000006087 Silane Coupling Agent Substances 0.000 claims description 14
- 239000007788 liquid Substances 0.000 claims description 14
- 239000004372 Polyvinyl alcohol Substances 0.000 claims description 12
- 239000004115 Sodium Silicate Substances 0.000 claims description 12
- 238000001035 drying Methods 0.000 claims description 12
- 238000010438 heat treatment Methods 0.000 claims description 12
- 229920002451 polyvinyl alcohol Polymers 0.000 claims description 12
- NTHWMYGWWRZVTN-UHFFFAOYSA-N sodium silicate Chemical compound [Na+].[Na+].[O-][Si]([O-])=O NTHWMYGWWRZVTN-UHFFFAOYSA-N 0.000 claims description 12
- 229910052911 sodium silicate Inorganic materials 0.000 claims description 12
- 239000011248 coating agent Substances 0.000 claims description 11
- 238000000576 coating method Methods 0.000 claims description 11
- 238000004321 preservation Methods 0.000 claims description 10
- 238000000034 method Methods 0.000 claims description 9
- 229910021536 Zeolite Inorganic materials 0.000 claims description 8
- HNPSIPDUKPIQMN-UHFFFAOYSA-N dioxosilane;oxo(oxoalumanyloxy)alumane Chemical compound O=[Si]=O.O=[Al]O[Al]=O HNPSIPDUKPIQMN-UHFFFAOYSA-N 0.000 claims description 8
- 239000010440 gypsum Substances 0.000 claims description 8
- 229910052602 gypsum Inorganic materials 0.000 claims description 8
- 229910021487 silica fume Inorganic materials 0.000 claims description 8
- 239000010457 zeolite Substances 0.000 claims description 8
- 238000001816 cooling Methods 0.000 claims description 6
- 239000012065 filter cake Substances 0.000 claims description 6
- 238000001914 filtration Methods 0.000 claims description 6
- 238000002386 leaching Methods 0.000 claims description 6
- 238000007493 shaping process Methods 0.000 claims description 6
- 238000007865 diluting Methods 0.000 claims description 2
- 238000002791 soaking Methods 0.000 claims description 2
- 238000010025 steaming Methods 0.000 claims 1
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- 239000000378 calcium silicate Substances 0.000 abstract description 6
- 229910052918 calcium silicate Inorganic materials 0.000 abstract description 6
- OYACROKNLOSFPA-UHFFFAOYSA-N calcium;dioxido(oxo)silane Chemical compound [Ca+2].[O-][Si]([O-])=O OYACROKNLOSFPA-UHFFFAOYSA-N 0.000 abstract description 6
- 230000007797 corrosion Effects 0.000 abstract description 4
- 238000005260 corrosion Methods 0.000 abstract description 4
- 125000005373 siloxane group Chemical group [SiH2](O*)* 0.000 abstract description 4
- 230000000694 effects Effects 0.000 abstract description 3
- 238000005245 sintering Methods 0.000 abstract description 3
- OYPRJOBELJOOCE-UHFFFAOYSA-N Calcium Chemical compound [Ca] OYPRJOBELJOOCE-UHFFFAOYSA-N 0.000 abstract description 2
- 239000004566 building material Substances 0.000 abstract description 2
- 239000011575 calcium Substances 0.000 abstract description 2
- 229910052791 calcium Inorganic materials 0.000 abstract description 2
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- 238000000151 deposition Methods 0.000 abstract description 2
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- 239000010703 silicon Substances 0.000 abstract description 2
- 229910052710 silicon Inorganic materials 0.000 abstract description 2
- 239000006072 paste Substances 0.000 description 19
- 238000002390 rotary evaporation Methods 0.000 description 9
- 238000006243 chemical reaction Methods 0.000 description 8
- 238000012360 testing method Methods 0.000 description 8
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- 239000011241 protective layer Substances 0.000 description 2
- 239000003469 silicate cement Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 241001374849 Liparis atlanticus Species 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 125000003277 amino group Chemical group 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 125000001309 chloro group Chemical group Cl* 0.000 description 1
- 239000004927 clay Substances 0.000 description 1
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- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 229920005646 polycarboxylate Polymers 0.000 description 1
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Abstract
The invention relates to high-expansion concrete with high bending toughness and a preparation method thereof, belongs to the technical field of building materials, and is mainly applied to the aspect of thin composite floor slabs. The concrete comprises the following components in parts by weight: 450-480 parts of Portland cement, 120-150 parts of mineral powder, 510-540 parts of fine aggregate, 65-80 parts of composite reinforcing fiber, 4.2-4.4 parts of water reducer and 180-200 parts of water; the composite reinforced fiber takes steel fiber as core material, siloxane groups are adhered to the surface of the steel fiber through chelation, then alkali paste taking fly ash as main material is coated on the surface, a porous protection layer containing silicon and calcium is formed through sintering, calcium silicate is loaded in a porous structure through a deposition method, corrosion protection is carried out on the steel fiber, and the bonding strength of the steel fiber and concrete is enhanced through physical embedding and hydration promotion, so that the toughening effect of the steel fiber is fully exerted.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to high-ductility concrete with high bending toughness and a preparation method thereof.
Background
The concrete material has the advantages of convenient material acquisition of aggregate, simple production process, low cost, excellent mechanical properties such as high compressive strength, good durability, corrosion resistance and the like, is widely applied to constructional engineering, and is one of the main civil engineering materials which are most studied and most widely applied in the world at present. Along with the high-speed development of economy and the further increase of social demands, the construction of various heavy concrete structures applied to severe conditions is continuously increased, and the development of engineering structures to large span, high rise, novel form and the like is now more severe in terms of concrete performance, so that the common concrete cannot meet the requirements of the current engineering construction; among them, concrete has the greatest brittleness and cannot be improved by materials.
It has long been found that the addition of hair, weeds, fibers, etc. to inorganic cementitious materials reduces their brittleness and reduces cracking, such as building houses by incorporating straw or weeds into clay for building walls. For this reason, researchers have proposed that fibers can be incorporated into cement matrices to improve their friability properties, fiber concrete has grown. The fiber concrete is a composite material which takes cement paste, mortar or concrete as a matrix and takes fibers as a reinforcing material, wherein the fiber types are various, and metal fibers, inorganic nonmetallic fibers, synthetic fibers, natural organic fibers and the like are included, the most widely used fiber concrete in the prior art is steel fiber concrete, and the toughness can be improved to a certain extent on the premise of ensuring the strength of the concrete; however, in long-term test researches, the bonding strength of the steel fiber and the concrete matrix is not high, the steel fiber and the matrix are easy to peel after being damaged, the toughening effect of the steel fiber can not be fully exerted, and the main reasons are as follows: the first is that the steel fiber is easy to corrode in the concrete, the corrosion layer is of a fluffy structure, so that the steel fiber is stripped from the concrete, and the second is that the steel fiber is combined with the concrete mainly by virtue of friction force, and the combination strength is not high. Accordingly, the present application prepares high-ductility concrete with high bending toughness, starting from improving the corrosiveness of steel fibers and the binding force with the concrete.
Disclosure of Invention
In order to solve the technical problems mentioned in the background art, the invention aims to provide high-ductility concrete with high bending toughness and a preparation method thereof.
The aim of the invention can be achieved by the following technical scheme:
a high-ductility concrete with high bending toughness comprises the following components in parts by weight: 450-480 parts of Portland cement, 120-150 parts of mineral powder, 510-540 parts of fine aggregate, 65-80 parts of composite reinforcing fiber, 4.2-4.4 parts of water reducer and 180-200 parts of water;
the composite reinforcing fiber is prepared by the following method:
step A1: mixing a silane coupling agent KH550 and tetrahydrofuran, slowly dropwise adding phosphorus oxychloride in a stirring state of 500-600rpm for reacting for 2-3 hours, carrying out substitution reaction on amino groups on molecules of the silane coupling agent KH550 and chlorine groups of the phosphorus oxychloride, then carrying out rotary evaporation to recover the tetrahydrofuran to obtain a chelating agent, diluting the chelating agent with water to form a modified liquid, adding steel fibers into the modified liquid, soaking for 12 hours at room temperature, enabling the chelating agent to have good chelation with the steel fibers, attaching the chelating agent on the surfaces of the steel fibers, coating siloxane groups on the surfaces of the steel fibers, taking out the steel fibers, leaching and drying to prepare modified steel fibers;
further, the dosage ratio of phosphorus oxychloride, the silane coupling agent KH550 and tetrahydrofuran is 0.1mol:0.32-0.35mol:200-280mL.
Further, the ratio of the amount of the steel fiber to the chelating agent was 10g:1.5-1.8g, wherein the chelating agent content in the modified liquid is 3.5-4.5wt%, and the steel fiber is selected from filaments prepared by a molten steel spinning method, and the diameter is 0.15mm.
Step A2: mixing and crushing fly ash, desulfurized gypsum, silica fume and zeolite to a fineness of not less than 325 meshes, adding water and polyvinyl alcohol, and uniformly stirring to prepare alkali paste;
further, the dosage mass ratio of the fly ash, the desulfurized gypsum, the silica fume and the zeolite is 1:0.35-0.42:0.1-0.14:0.05-0.08.
Further, the water content of the alkali paste is 78-82%, and the polyvinyl alcohol accounts for 0.7-0.9wt%.
Step A3: coating alkali paste on the surface of modified steel fiber, baking at 55-60 ℃ for 30-40min for shaping, reacting siloxane groups introduced on the surface of the modified steel fiber with inorganic particles in the alkali paste under alkaline condition, tightly attaching the alkali paste on the surface of the fiber, then placing the fiber in a roasting furnace, heating to 160-180 ℃ for roasting for 30-40min, heating to 950-1000 ℃ for roasting for 1.2-1.5h, sintering the alkali paste to attach on the surface of the modified steel fiber to form a porous protective layer containing silicon and calcium, cooling to room temperature, and shearing into short fibers with the length of 30-50mm to prepare the composite chopped fibers;
further, the alkali paste is coated on the modified steel fiber in an amount of 2.5-2.8g/m.
Step A4: preparing a sodium carbonate solution with the pH value of 8.0-9.0, adding sodium silicate and calcium nitrate, stirring and dissolving, performing ultrasonic oscillation for 20-30min, adding the composite chopped fiber, standing for 24h to form calcium silicate to be attached and deposited on the surface of the composite chopped fiber, filtering, taking a filter cake, and drying to prepare the composite reinforced fiber;
further, the dosage ratio of the composite chopped fiber, the sodium silicate, the calcium nitrate and the sodium carbonate solution is 100g:8.5-10g:3-5g:550-600mL.
The preparation method of the high-ductility concrete with high bending toughness comprises the following steps: mixing silicate cement, mineral powder, fine aggregate, composite reinforcing fiber and a water reducing agent, and adding water to mix uniformly to prepare the high-expansion concrete with high bending toughness.
The invention has the beneficial effects that:
the invention adds a compound reinforcing fiber into concrete, which takes steel fiber as core material, prepares a chelating agent containing phosphorus through substitution reaction of silane coupling agent KH550 and phosphorus oxychloride, adheres organic matters containing siloxane groups to the surface after the steel fiber is treated, improves the surface activity of the steel fiber, coats alkali paste taking fly ash as main material on the surface, reacts with inorganic particles in the alkali paste, tightly adheres the alkali paste to the surface of the fiber, forms a porous protective layer containing calcium silicate after sintering, loads calcium silicate in a porous structure through a deposition method, compared with the existing steel fiber concrete, the sintered layer on the surface of the steel fiber protects the steel fiber, reduces the strength reduction caused by steel fiber corrosion, enhances the embedding strength with the concrete, ensures that the steel fiber is not easy to peel off from the concrete, is rich in calcium silicate components and the deposited calcium silicate is easy to form hydration with the concrete, forms a band on the near layer of the steel fiber, further strengthens the bonding strength of the steel fiber and fully exerts the functions of toughening the steel fiber.
Detailed Description
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, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the invention without making any inventive effort, are intended to be within the scope of the invention.
Example 1, this example produces a composite reinforcing fiber, specifically as follows:
a1, mixing a silane coupling agent KH550 and tetrahydrofuran, applying 600rpm mechanical stirring, slowly dropwise adding phosphorus oxychloride within 40min, continuously maintaining stirring for reaction after dropwise adding, and integrally adding for 2h, wherein the dosage ratio of the phosphorus oxychloride, the silane coupling agent KH550 and the tetrahydrofuran is 0.1mol:0.35mol:280mL, recycling tetrahydrofuran by rotary evaporation after reaction, and preparing a chelating agent by taking a rotary evaporation product;
preparing a chelating agent and water into a modified liquid with the concentration of 5.5wt%, preparing steel fiber filaments with the diameter of 0.15mm by a molten steel filament drawing method, immersing the steel fibers into the modified liquid according to the dosage of the chelating agent of 1.5g/10g for 12 hours at room temperature, taking out the steel fibers, leaching with water, and drying with hot air for 10 minutes to prepare the modified steel fibers.
a2, mixing fly ash, desulfurized gypsum, silica fume and zeolite according to a mass ratio of 1: mixing and crushing 0.35:0.14:0.08, sieving with 325 mesh sieve, adding water and polyvinyl alcohol, stirring, controlling the polyvinyl alcohol ratio to 0.9wt% and the water content to 82%, and making into alkali paste.
a3, coating alkali paste on the surface of the modified steel fiber, controlling the coating amount to be 2.8g/m, baking the coated fiber at 60 ℃ for 30min for shaping, then placing the fiber in a roasting furnace, firstly heating to 180 ℃ for heat preservation and roasting for 30min, then heating to 1000 ℃ for heat preservation and roasting for 1.2h, cooling to room temperature, and shearing the fiber into short fiber with the length of 30mm by a punching machine to prepare the composite chopped fiber.
a4, dissolving sodium carbonate with water to dilute the sodium carbonate into a sodium carbonate solution with the pH value of 9.0, adding sodium silicate and calcium nitrate, stirring and dissolving, performing ultrasonic dispersion for 20min at 28kHz, adding composite chopped fibers, and standing for 24h, wherein the dosage ratio of the composite chopped fibers to the sodium silicate to the calcium nitrate to the sodium carbonate solution is 100g:10g:5g:600mL, filtering to obtain a filter cake, and drying at 60 ℃ for 3h to prepare the composite reinforced fiber.
Example 2, this example produces a composite reinforcing fiber, specifically as follows:
a1, mixing a silane coupling agent KH550 and tetrahydrofuran, applying 500rpm mechanical stirring, slowly dropwise adding phosphorus oxychloride within 60min, continuously maintaining stirring for reaction after dropwise adding, and integrally adding for 3h, wherein the dosage ratio of the phosphorus oxychloride, the silane coupling agent KH550 and the tetrahydrofuran is 0.1mol:0.32mol:200mL, recycling tetrahydrofuran by rotary evaporation after reaction, and preparing a chelating agent by taking a rotary evaporation product;
preparing a chelating agent and water into a modified liquid with the concentration of 7.5wt%, preparing steel fiber filaments with the diameter of 0.15mm by a molten steel filament drawing method, immersing the steel fibers into the modified liquid according to the dosage of the chelating agent of 1.8g/10g for 12 hours at room temperature, taking out the steel fibers, leaching with water, and drying with hot air for 10 minutes to prepare the modified steel fibers.
a2, mixing fly ash, desulfurized gypsum, silica fume and zeolite according to a mass ratio of 1: mixing and crushing 0.42:0.1:0.05, sieving with 325 mesh sieve, adding water and polyvinyl alcohol, stirring, controlling the polyvinyl alcohol ratio to 0.7wt% and the water content to 78%, and making into alkali paste.
a3, coating alkali paste on the surface of the modified steel fiber, controlling the coating amount to be 2.5g/m, baking the coated fiber at 55 ℃ for 40min for shaping, then placing the fiber in a roasting furnace, firstly heating to 160 ℃ for heat preservation and roasting for 40min, then heating to 950 ℃ for heat preservation and roasting for 1.5h, cooling to room temperature, and shearing the fiber into short fiber with the length of 50mm by a punching machine to prepare the composite chopped fiber.
a4, dissolving sodium carbonate with water to dilute the sodium carbonate into a sodium carbonate solution with the pH value of 8.0, adding sodium silicate and calcium nitrate, stirring and dissolving, performing ultrasonic dispersion for 30min at 28kHz, adding composite chopped fibers, and standing for 24h, wherein the dosage ratio of the composite chopped fibers to the sodium silicate to the calcium nitrate to the sodium carbonate solution is 100g:8.5g:3g:550mL, filtering to obtain a filter cake, and drying at 60 ℃ for 3h to prepare the composite reinforced fiber.
Example 3, this example produces a composite reinforcing fiber, specifically as follows:
a1, mixing a silane coupling agent KH550 and tetrahydrofuran, applying 600rpm mechanical stirring, slowly dropwise adding phosphorus oxychloride within 50min, continuously maintaining stirring for reaction after dropwise adding, and integrally adding for 2.2h, wherein the dosage ratio of the phosphorus oxychloride, the silane coupling agent KH550 and the tetrahydrofuran is 0.1mol:0.34mol:250mL, recycling tetrahydrofuran by rotary evaporation after reaction, and preparing a chelating agent by taking a rotary evaporation product;
preparing a chelating agent and water into a modified liquid with the concentration of 6.0wt%, preparing steel fiber filaments with the diameter of 0.15mm by a molten steel filament drawing method, immersing the steel fibers into the modified liquid according to the dosage of the chelating agent of 1.6g/10g for 12 hours at room temperature, taking out the steel fibers, leaching with water, and drying with hot air for 10 minutes to prepare the modified steel fibers.
a2, mixing fly ash, desulfurized gypsum, silica fume and zeolite according to a mass ratio of 1: mixing and crushing 0.38:0.12:0.06, sieving with 325 mesh sieve, adding water and polyvinyl alcohol, stirring, controlling the polyvinyl alcohol ratio to 0.8wt% and the water content to 80%, and making into alkali paste.
a3, coating alkali paste on the surface of the modified steel fiber, controlling the coating amount to be 2.6g/m, baking the coated fiber at 60 ℃ for 35min for shaping, then placing the fiber in a roasting furnace, firstly heating to 170 ℃ for heat preservation and roasting for 40min, then heating to 980 ℃ for heat preservation and roasting for 1.3h, cooling to room temperature, and shearing the fiber into short fiber with the length of 50mm by a punching machine to prepare the composite chopped fiber.
a4, dissolving sodium carbonate with water to dilute the sodium carbonate into a sodium carbonate solution with the pH value of 9.0, adding sodium silicate and calcium nitrate, stirring and dissolving, performing ultrasonic dispersion for 30min at 28kHz, adding composite chopped fibers, and standing for 24h, wherein the dosage ratio of the composite chopped fibers to the sodium silicate to the calcium nitrate to the sodium carbonate solution is 100g:9g:4g:580mL, filtering to obtain a filter cake, and drying at 60 ℃ for 3h to prepare the composite reinforced fiber.
Example 4, this example produces a composite reinforcing fiber, specifically as follows:
a1, mixing a silane coupling agent KH550 and tetrahydrofuran, applying 600rpm mechanical stirring, slowly dropwise adding phosphorus oxychloride within 60min, continuously maintaining stirring for reaction after dropwise adding, and integrally adding for 2.5h, wherein the dosage ratio of the phosphorus oxychloride, the silane coupling agent KH550 and the tetrahydrofuran is 0.1mol:0.34mol:280mL, recycling tetrahydrofuran by rotary evaporation after reaction, and preparing a chelating agent by taking a rotary evaporation product;
preparing a chelating agent and water into a modified liquid with the concentration of 7.0wt%, preparing steel fiber filaments with the diameter of 0.15mm by a molten steel filament drawing method, immersing the steel fibers into the modified liquid according to the dosage of the chelating agent of 1.6g/10g for 12 hours at room temperature, taking out the steel fibers, leaching with water, and drying with hot air for 10 minutes to prepare the modified steel fibers.
a2, mixing fly ash, desulfurized gypsum, silica fume and zeolite according to a mass ratio of 1: mixing and crushing 0.4:0.12:0.07, sieving with a 325 mesh sieve, adding water and polyvinyl alcohol, stirring uniformly, controlling the polyvinyl alcohol ratio to be 0.9wt% and the water content to be 80%, and preparing the alkali paste.
a3, coating alkali paste on the surface of the modified steel fiber, controlling the coating amount to be 2.5g/m, baking the coated fiber at 55 ℃ for 35min for shaping, then placing the fiber in a roasting furnace, firstly heating to 180 ℃ for heat preservation and roasting for 40min, then heating to 980 ℃ for heat preservation and roasting for 1.5h, cooling to room temperature, and shearing the fiber into short fiber with the length of 40mm by a punching machine to prepare the composite chopped fiber.
a4, dissolving sodium carbonate with water to dilute the sodium carbonate into a sodium carbonate solution with the pH value of 9.0, adding sodium silicate and calcium nitrate, stirring and dissolving, performing ultrasonic dispersion for 25min at 28kHz, adding composite chopped fibers, and standing for 24h, wherein the dosage ratio of the composite chopped fibers to the sodium silicate to the calcium nitrate to the sodium carbonate solution is 100g:9.5g:4.5g:600mL, filtering to obtain a filter cake, and drying at 60 ℃ for 3h to prepare the composite reinforced fiber.
The following examples prepared high tensile concrete with high flexural toughness, the formulation involved the following raw materials:
portland cement selected from P.O42.5R Portland cement manufactured by Anhui sea snail Cement Co., ltd;
mineral powder selected from S95 grade mineral powder produced by Wuwu new building materials Co., ltd;
fine aggregate selected from natural river sand with fineness modulus of 2.6, and concrete grading shown in table 1:
the water reducer is selected from PCA-I high-efficiency polycarboxylate water reducer and is produced by Jiangsu Su Bote New Material Co., ltd.
The preparation method of the concrete comprises the following steps: silicate cement, mineral powder, fine aggregate, composite reinforcing fiber and a water reducer are added into a mixer to be mixed for 10min at 60rpm, and then water is added according to the following ratio of 3:1, distributing, namely adding and stirring for 12 minutes in two times to prepare concrete;
the specific ingredients are shown in table 2:
taking a cubic mold with the side length of 100mm and a prismatic mold with the size of 40 multiplied by 160mm, injecting concrete, vibrating and compacting, trowelling and standing, removing the mold after 40 hours, and carrying out standard curing for 28d and the age of 56d to obtain a cubic and prismatic sample;
taking a cube sample, loading the sample at a constant speed with a loading rate of 5kN/s, and carrying out compressive strength test on the sample, wherein specific test data are shown in Table 3:
as can be seen from the data in Table 3, the compressive strength of the concrete prepared by the invention reaches 62.15-65.70MPa, and the concrete has good compressive property.
Based on the test data, taking a cube sample, loading the cube sample to the compressive strength of 80% at a constant speed according to the loading rate of 2kN/s, naturally curing for 90d after pressure relief, and carrying out the compressive test again, wherein the specific test data are shown in Table 4:
as can be seen from the data in Table 4, the secondary compressive strength of the concrete prepared by the method is kept between 61.85 and 63.95MPa, and the concrete has good compressive toughness and damage resistance.
The prism samples prepared above were subjected to a flexural test using a three-point flexural test method at a loading rate of 0.5kN/s, and specific test data are shown in Table 5:
as can be seen from the data in Table 5, the flexural strength of the concrete prepared by the invention reaches 23.45-25.80MPa, and the concrete has good flexural performance.
In the description of the present specification, the descriptions of the terms "one embodiment," "example," "specific example," and the like, mean that a particular feature, structure, material, or characteristic described in connection with the embodiment or example is included in at least one embodiment or example of the present invention. In this specification, schematic representations of the above terms do not necessarily refer to the same embodiments or examples. Furthermore, the particular features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.
The foregoing is merely illustrative and explanatory of the invention, as various modifications and additions may be made to the particular embodiments described, or in a similar manner, by those skilled in the art, without departing from the scope of the invention or exceeding the scope of the invention as defined in the claims.
Claims (8)
1. A high-ductility concrete having high bending toughness, characterized by comprising, in parts by weight: 450-480 parts of Portland cement, 120-150 parts of mineral powder, 510-540 parts of fine aggregate, 65-80 parts of composite reinforcing fiber, 4.2-4.4 parts of water reducer and 180-200 parts of water;
the composite reinforcing fiber is prepared by the following method:
step A1: mixing a silane coupling agent KH550 and tetrahydrofuran, slowly dropwise adding phosphorus oxychloride in a stirring state to react for 2-3 hours, steaming in a rotary mode to recover the tetrahydrofuran to obtain a chelating agent, diluting the chelating agent with water to obtain a modified liquid, adding steel fibers into the modified liquid, soaking for 12 hours at room temperature, taking out the steel fibers, leaching and drying to obtain modified steel fibers;
step A2: mixing and crushing fly ash, desulfurized gypsum, silica fume and zeolite to a fineness of not less than 325 meshes, adding water and polyvinyl alcohol, and uniformly stirring to prepare alkali paste;
step A3: coating alkali paste on the surface of modified steel fiber, baking at 55-60 ℃ for 30-40min for shaping, then placing in a baking furnace, heating to 160-180 ℃ for heat preservation and baking for 30-40min, heating to 950-1000 ℃ for heat preservation and baking for 1.2-1.5h, cooling to room temperature, and cutting into short fibers with the length of 30-50mm to prepare composite chopped fibers;
step A4: preparing a sodium carbonate solution with the pH value of 8.0-9.0, adding sodium silicate and calcium nitrate, stirring and dissolving, ultrasonically oscillating for 20-30min, adding the composite chopped fiber, standing for 24h, filtering, taking a filter cake, and drying to prepare the composite reinforced fiber.
2. The high-ductility concrete with high flexural toughness according to claim 1, wherein the ratio of phosphorus oxychloride, silane coupling agent KH550 and tetrahydrofuran is 0.1mol:0.32-0.35mol:200-280mL.
3. A high tensile concrete with high bending toughness according to claim 2, wherein the ratio of steel fiber to chelating agent is 10g:1.5-1.8g, the chelating agent content in the modified liquid is 3.5-4.5wt%, and the diameter of the steel fiber is 0.15mm.
4. The high-ductility concrete with high bending toughness according to claim 1, wherein the mass ratio of fly ash, desulfurized gypsum, silica fume and zeolite is 1:0.35-0.42:0.1-0.14:0.05-0.08.
5. The high-ductility concrete with high bending toughness according to claim 4, wherein the water content of the alkali paste is 78-82% and the polyvinyl alcohol is 0.7-0.9wt%.
6. A high tensile concrete with high bending toughness according to any one of claims 3 and 5, wherein the alkali paste is applied to the modified steel fibers in an amount of 2.5-2.8g/m.
7. The high tensile concrete with high bending toughness according to claim 6, wherein the ratio of the amount of the composite chopped fiber, sodium silicate, calcium nitrate and sodium carbonate solution is 100g:8.5-10g:3-5g:550-600mL.
8. The method for preparing high-ductility concrete with high bending toughness according to claim 1, wherein the portland cement, mineral powder, fine aggregate, composite reinforcing fiber and water reducing agent are mixed, and water is added to mix uniformly, so that the high-ductility concrete with high bending toughness is prepared.
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