Preparation method of long-life low-carbon ferrite aluminate cement concrete and pipe segment prepared by the method

Abstract

The application belongs to the field of concrete products, and particularly relates to a long-life low-carbon ferrite aluminate cement concrete and a preparation method of a pipe segment prepared by the ferrite aluminate cement concrete. First, a concrete pipe segment mold is sprayed with an oily release agent 12 hours in advance, and then sprayed with a water-based release agent after 2 hours. Ferrite aluminate cement, non-autoclaved functional materials, corrosion-resistant and wear-resistant reinforcing materials, fibers, water-reducing agents, fine aggregates, coarse aggregates and water are put into a mixer according to the formula amount to obtain ferrite aluminate cement concrete for pipe segments. The mixed ferrite aluminate cement concrete is poured into the mold in three times, and then the pipe segment concrete is cured with a curing agent. Finally, the pipe segment is demolded and placed in water for normal temperature curing. The concrete pipe segment improves the wear resistance of the concrete, gives the pipe segment better scouring resistance, increases the compactness of the pipe segment, controls the hydration rate of the ferrite aluminate cement, improves the compactness of the concrete pipe segment, improves the corrosion resistance of the concrete, and improves the durability of the concrete.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of concrete products, and particularly relates to a long-life low-carbon ferrite aluminate cement concrete and a preparation method of a pipe segment prepared therefrom. BACKGROUND

[0002] The ferrite aluminate cement concrete has the characteristics of fast setting, fast hardening, early strength, high strength, low shrinkage, high volume stability, wear resistance, erosion resistance, and high serviceability, and is particularly suitable for marine engineering and has been successfully applied to the engineering fields with special performance requirements such as the Antarctic research station, the Dongshan Island Nanmen seawall in Fujian, the State Oceanic Administration, and meets the needs of national economic construction.

[0003] In recent years, with the continuous adjustment of China's energy structure, the proportion of green and clean energy such as photovoltaic, wind power and nuclear power has been increasing. In order to improve energy security and promote green development, China has planned to continue to implement nuclear power projects. Nuclear power plants need cooling water to take away heat, and the sea is a natural large heat exchange field. Using seawater as a cooling medium, using seawater direct flow circulation cooling technology to take heat to the sea is economical and environmentally friendly.

[0004] The drainage tunnel is a channel for seawater direct flow circulation, and most of them are constructed by the shield method. The large discharge, high flow rate and high and low temperature seawater have a strong scouring and eroding effect on the pipe segment, which poses a great challenge to the quality of the concrete pipe segment. Once the durability of the pipe segment is not up to standard, damage will occur, which will affect the normal operation of the nuclear power plant. Moreover, the deep underground characteristics also determine the complexity and difficulty of replacement. Therefore, the wear resistance, erosion resistance and corrosion resistance of the pipe segment for the nuclear power project drainage tunnel are extremely high. Compared with traditional Portland cement, ferrite aluminate cement concrete is more suitable for producing and preparing pipe segments for drainage tunnels.

[0005] However, due to the rapid hydration of ferrite aluminate cement, the water loss on the surface of the concrete is too fast, and combined with the arc-shaped structure of the pipe segment, once the surface wet curing cannot keep up, even if the pipe segment is subjected to secondary troweling, the upper surface of the pipe segment is prone to plastic shrinkage cracking. In addition, due to the concentrated heat of hydration, the temperature stress is large during the cooling process, and temperature cracking is prone to occur. These cracked pipe segments can only be scrapped and cannot be applied to solid structures. Moreover, the external erosion medium will enter the concrete along the cracks and damage the structure. Therefore, although ferrite aluminate cement has good corrosion resistance and erosion resistance, how to use it to prepare long-life low-carbon ferrite aluminate cement concrete pipe segments is still a technical problem that needs to be solved urgently. SUMMARY

[0006] The main purpose of the present application is to provide a long-life low-carbon ferrite aluminate cement concrete and a preparation method of a pipe segment prepared therefrom, and to solve the technical problems of eliminating the surface plastic shrinkage and temperature cracking in the cooling process during the preparation of the ferrite aluminate cement concrete pipe segment, and realizing the low-carbon preparation of the concrete pipe segment and giving it the long-term service ability in complex environment, so as to match the design service life of the pipe segment and the nuclear power engineering.

[0007] The specific technical solutions of the present application are as follows:

[0008] A long-life low-carbon ferrite aluminate cement concrete, by weight, comprises:

[0009] Ferrite aluminate cement: 400-450 parts;

[0010] Non-autoclaved functional material: 60-90 parts;

[0011] Corrosion-resistant and wear-resistant reinforcing material: 40-80 parts;

[0012] Fiber: 10-25 parts

[0013] Water reducing agent: 2-3 parts;

[0014] Fine aggregate: 640-700 parts;

[0015] Coarse aggregate: 950-1040 parts.

[0016] Preferably, the ferrite aluminate cement is a high-iron ferrite aluminate cement with a strength grade of 42.5 MPa or more, and the Blaine specific surface area thereof is (400±20) m 2 / kg; the cement clinker mineral phase for preparing the ferrite aluminate cement contains 45.0-55.0% anhydrous calcium sulphoaluminate, 15.0-25.0% dicalcium silicate and 30.0-35.0% iron phase solid solution by weight percentage, and the ferrite aluminate cement contains 10.0-12.0% of Fe2O3. By chemically regulating the mineral phase composition of the ferrite aluminate cement clinker and physically regulating the particle fineness, the hydration rate of the ferrite aluminate cement is optimized, so that the hydration temperature rise reaches a peak in about 2 hours. At the same time, the hydration heat of the ferrite aluminate cement itself is used in cooperation with the non-autoclaved functional material to promote the rapid construction of the concrete strength, so as to realize the non-autoclaved and low-carbon preparation of the concrete pipe segment. In addition, by increasing the iron phase content in the clinker, the wear resistance of the concrete can be further improved, and the pipe segment has better erosion resistance.

[0017] Preferably, the non-autoclaved functional material comprises, by weight percentage:

[0018] Lithium slag powder: 20.0-30.0%,

[0019] Fly ash: 30.0-40.0%,

[0020] Ground slag: 5.0-10.0%,

[0021] Ground slag: 5.0-10.0%,

[0022] Gypsum: 5.0-10.0%,

[0023] Dextrin: 0.5%.

[0024] The above non-autoclaved functional material acts to accelerate the hydration of the ferrite cement concrete, and more hydration heat is generated in a short time. At the same time, by using the hydration temperature rise of the concrete, a synergistic and mutual promotion chemical reaction occurs with the ferrite cement under the thermal excitation effect, and the non-autoclaved low-carbon preparation of the concrete segment can be realized without external heat source curing.

[0025] Preferably, the lithium slag powder is carbonized lithium slag powder, and the specific surface area is (350±20) m 2 / kg. The preparation process of the carbonized lithium slag powder is that the lithium slag containing water is first carbonized by carbon dioxide, the carbonization time of the material is controlled to be 30-50 min, the lithium oxide in the lithium slag reacts to generate lithium carbonate in the presence of water, then the lithium slag is dried by using 120-140℃ waste heat, and then the ball mill is used for grinding treatment.

[0026] Preferably, the fly ash is finely ground fly ash, and the performance index meets the quality of grade II ash, and the 45μm sieve residue is ≤3.0%. The finely ground fly ash mainly uses mechanical force effect to break the large glass beads in the fly ash, and release more small beads. On the one hand, the workability of the concrete is improved, and on the other hand, the low-calcium C-S-H gel is generated by participating in the chemical reaction, and the strength construction of the concrete is accelerated.

[0027] Preferably, the ground slag powder is finely ground slag powder, and the specific surface area is (650±20) m 2 / kg, and the 28d activity index is ≥105%. The ground slag powder acts to synergistically participate in the hydration reaction, on the one hand, increases the calcium hydroxide content of the system, and on the other hand, generates more C-S-H gel, which increases the strength of the concrete while optimizing the crystal-gel ratio of the concrete and improving the toughness of the concrete segment.

[0028] Preferably, the silica fume is the dust discharged through the flue during the smelting of ferrosilicon alloy or industrial silicon, and the powder material mainly composed of amorphous silicon dioxide is obtained by collection, and the SiO2 content is ≥90.0%, and the specific surface area (BET method) is ≥18 m 2 / g. The silica fume mainly acts to provide high-activity SiO2 to generate more C-S-H gel, and at the same time, fill the pores by using its superfine characteristics to form a tight packing and increase the compactness and impermeability of the segment.

[0029] Preferably, the gypsum is anhydrite, and the performance meets the technical requirements of GB / T5483 "Natural Gypsum", wherein SO3≥48%, and the content of crystal water is ≤3.0%.

[0030] Preferably, the dextrin is β-cyclodextrin, and the specific optical rotation is +(162±2)°, and the particle size distribution is 20.0-30.0 μm. The dextrin acts in cooperation with the lithium slag powder to regulate the hydration rate of the ferrite-aluminate cement, so as to ensure the construction performance of the concrete within 30 minutes and meet the pouring requirements.

[0031] Preferably, the corrosion-resistant and wear-resistant reinforcing material comprises, by weight percentage:

[0032] Steel slag powder: 30.0-40.0%,

[0033] Alunite: 40.0-60.0%,

[0034] Carborundum powder: 10.0-20.0%.

[0035] The above-mentioned corrosion-resistant and wear-resistant reinforcing material acts to increase the compactness and wear resistance of the concrete segment, thereby improving the erosion resistance and corrosion resistance of the concrete segment.

[0036] Preferably, the steel slag powder is a steel slag micro-powder prepared by grinding the carbon dioxide gas-cooled steel slag, and the D 50 ≤5.0 μm, and the Blaine specific surface area is (680±20) m 2 / kg, and the content of iron oxide is ≥30%. The f-CaO content in the carbon dioxide gas-cooled steel slag is 2.5-4.0%, and the f-MgO content is 2.0-4.0%. The steel slag micro-powder has the dual effects of increasing the wear resistance and compactness of the concrete. On the one hand, the steel slag micro-powder has a high content of iron oxide and good wear resistance, which can increase the wear resistance of the ferrite-aluminate cement concrete segment. On the other hand, the carbon dioxide gas-cooled steel slag retains a certain content of f-CaO and f-MgO, and the expansion products generated by the hydration of the f-CaO and f-MgO can further fill and compact the internal pores of the concrete, change the large pores into small pores, and optimize the pore structure, thereby increasing the compactness of the concrete segment and optimizing and improving the corrosion resistance of the concrete.

[0037] Preferably, the alunite is finely ground alunite, the content of pure alunite is ≥70%, the K / Na ratio is ≥5.5, and the specific surface area is (350±20) m 2 / kg. The alunite acts to continuously generate the expansion product alunite hydrate through hydration reaction, in-situ fill and compact the concrete, and serve as a long-term self-repairing material, so that the concrete segment is in a slightly expanded state.

[0038] The preferred corundum powder is fine corundum powder with fineness of 45um and residue of 15.0% or less. The corundum powder and the steel slag powder are stacked to enhance the wear resistance of the concrete.

[0039] The preferred fiber is a mixture of steel fiber and polypropylene fiber. The steel fiber is 85.0-95.0% by weight, and the PVC fiber is 5.0-15.0% by weight. The steel fiber is an alloy structural steel with a length of 20mm or less, a longitudinal straight shape, hooks at both ends, and fine surface indentations. The polypropylene fiber has a length of 15mm or less and an equivalent diameter of 30um. The polypropylene fiber mainly plays a micro-toughening role and cooperates with the steel fiber to increase the toughness of the concrete segment from the micro and macro levels. On the other hand, it reduces the surface plastic shrinkage cracking during the preparation of the segment. When the segment is subjected to external load, the steel fiber and polypropylene fiber can distribute stress and reduce crack width.

[0040] The preferred water reducing agent is a polycarboxylic acid and melamine composite high-performance powder water reducing agent. The polycarboxylic acid water reducing agent is 50.0-75.0% by weight, and the melamine water reducing agent is 25.0-50.0% by weight. The water reducing rate is 25% or more. The water reducing agent reduces the water consumption per unit of concrete, reduces capillary pores, improves the compactness and impermeability of the concrete, and thus improves the corrosion and wear resistance of the concrete segment.

[0041] The preferred fine aggregate is a mixture of machine-made sand and carbonized steel slag. The machine-made sand is 60.0-75.0% by weight, and the steel slag is 25.0-40.0% by weight. The specific particle size of the machine-made sand is 5.0-6.0, the MB value is 1.0 or less, the stone powder content is 10.0% or less, and the flaky particle content is 5.0% or less. The carbonized steel slag is a steel slag treated by carbon dioxide to eliminate its poor stability problem. The particle size range is 2.5-5mm, and the Fe2O3 content is 30% or more. Due to the high sphericity of the steel slag particles, the introduction of the steel slag as a fine aggregate can greatly improve the fluidity of the concrete, help reduce the water consumption per unit, and improve the durability of the concrete segment.

[0042] The preferred coarse aggregate is a shaped artificial fine gravel, at least one of a two-stage, three-stage or multi-stage aggregate with a maximum particle size of 25.0mm and a close-packed void ratio of 35.0-37.0%. The irregular particle content is 3.0% or less. By using multi-stage aggregate, the void ratio of the aggregate can be minimized, and the irregular particles can be controlled to minimize the amount of mortar required to fill the aggregate voids, improve the compactness of the concrete, and improve the durability of the concrete.

[0043] A method for preparing a long-life low-carbon ferrum aluminate cement concrete segment, comprising the following steps:

[0044] (1) Mould coating release agent: the concrete segment mould is sprayed with an oily release agent 12 hours in advance, and then sprayed with a water-based release agent after 2 hours;

[0045] (2) Concrete mixing preparation: the segment is filled with dry iron aluminate cement concrete mixture into a concrete transport mixer, water is added according to the formula, slow stirring for 240-300 seconds, then fast stirring for 60-90 seconds, and then standing for 120 seconds to obtain the iron aluminate cement concrete for the segment, and the concrete slump is controlled at 140-180 mm;

[0046] (3) Segment concrete pouring: the mixed iron aluminate cement concrete is poured into the mould in three times, the first layer, one third of the thickness of the segment is poured, vibrated at 0.80-0.85 MPa for 180 seconds, and the surface floating slurry is scraped off; the second layer, two thirds of the thickness of the segment is poured, vibrated at 0.90-0.95 MPa for 120 seconds, and the surface floating slurry is scraped off; the third layer, the top of the segment is poured, vibrated at 0.95-1.00 MPa for 100 seconds, and the excess concrete is scraped off; at the same time, a reduced size test piece is poured, a temperature measuring sensor is embedded in the test piece, and the demoulding time is determined;

[0047] (4) Segment concrete curing: a layer of concrete curing agent is sprayed on the surface of the concrete, a layer of plastic film is covered, the film is removed after 30 minutes, and the concrete is checked whether it is close to initial setting. If it is close to initial setting, secondary trowelling is carried out, then water is sprayed for moisture curing, then the plastic film is covered, and cotton is covered on the film for heat preservation and curing;

[0048] (5) Segment demoulding: when the temperature in the reduced size test piece is reduced to below 40℃, and the temperature difference between the inside and outside environment is less than 20℃, the cotton, the film, and the mould are removed in sequence, then the segment is lifted out of the mould by a suction cup, and placed in water for normal temperature curing.

[0049] Preferably, the first oily release agent in step (1) is used to protect the segment mould and eliminate the mould corrosion problem caused by the iron aluminate cement concrete; and the second water-based release agent is used to reduce the surface tension of the concrete, eliminate the air holes on the surface of the concrete, and improve the surface density, so as to improve the wear resistance of the surface of the concrete segment.

[0050] Preferably, the water quantity for single concrete in step (2) is 150-160 kg.

[0051] Preferably, the concrete curing agent is used in an amount of 0.15-0.20 kg / m 2 .

[0052] The present application has the following advantages due to the use of the above technical solutions:

[0053] 1. Utilize the self-hydration heat of ferrite aluminate cement to promote the rapid construction of concrete strength, realize the non-autoclaved curing of concrete segments, and low-carbon preparation. At the same time, increase the content of iron phase in cement clinker, further improve the wear resistance of concrete, and give the segment better erosion resistance.

[0054] 2. By introducing mineral powder, improve the workability of concrete, speed up the construction of concrete strength, increase the content of calcium hydroxide in the system, optimize the crystal-gel ratio of concrete, and improve the toughness of concrete segment. At the same time, use silica fume to provide high-activity SiO2 to generate more C-S-H gel, and use its superfine characteristics to fill the pores, form a tight packing, increase the compactness of the segment, control the hydration rate of ferrite aluminate cement, and ensure the construction performance of concrete within 30 minutes to meet the pouring demand.

[0055] 3. By introducing corrosion-resistant and wear-resistant reinforcing materials, increase the wear resistance of ferrite aluminate cement concrete, improve the compactness of concrete segment, and improve the corrosion resistance of concrete. Alunite fills and densifies the concrete in situ, equivalent to a long-term self-repairing material, keeping the concrete segment in a slightly expanded state. Steel fiber and polypropylene fiber increase the toughness of concrete segment from micro and macro levels, and reduce the surface plastic shrinkage cracking during the preparation of the segment; by reducing the water consumption per unit of concrete and reducing capillary pores, the compactness and impermeability of concrete are improved, thereby improving the corrosion resistance and wear resistance of concrete segment; by using multi-graded aggregate, the aggregate void ratio can be minimized, and irregular particles can be controlled to minimize the amount of mortar required for filling aggregate and ensure fluidity, further improve the compactness of concrete, and improve the durability of concrete.

[0056] The above description is only a summary of the technical solutions of the present application. In order to more clearly understand the technical means of the present application and can be implemented according to the content of the specification, the following will be described in detail as follows. DETAILED DESCRIPTION

[0057] In order to further illustrate the technical means and effects adopted by the present application to achieve the predetermined purpose of the application, the following will be described in detail as follows in combination with the preferred embodiments of the present application. In addition, the specific features, structures, or characteristics in one or more embodiments can be combined in any suitable form.

[0058] Example 1

[0059] A long-life low-carbon ferrite aluminate cement concrete, by weight, comprises:

[0060] Ferrite aluminate cement: 400 parts;

[0061] Non-autoclaved curing functional material: 60 parts;

[0062] Corrosion and wear resistant reinforcing material: 40 parts;

[0063] Fiber: 10 parts

[0064] Water reducing agent: 2 parts;

[0065] Fine aggregate: 700 parts;

[0066] Coarse aggregate: 1040 parts.

[0067] The ferrite aluminate cement is a high-iron phase ferrite aluminate cement with a strength grade of 42.5 MPa or more, and a Blaine specific surface area of (400±20) m 2 / kg; the cement clinker mineral phase for preparing the ferrite aluminate cement contains, by weight percentage, 45.0-55.0% anhydrous calcium sulphoaluminate, 15.0-25.0% dicalcium silicate and 30.0-35.0% iron phase solid solution, and the ferrite aluminate cement has a content of 10.0-12.0% of iron trioxide.

[0068] The autoclaved curing-free functional material comprises, by weight percentage:

[0069] Lithium slag powder: 20.0%,

[0070] Fly ash: 30.0%,

[0071] Mineral powder: 30.0%,

[0072] Silica fume: 10.0%,

[0073] Gypsum: 9.5%,

[0074] Dextrin: 0.5%.

[0075] The lithium slag powder is carbonized lithium slag powder, and has a specific surface area of (350±20) m 2 / kg; the preparation process of the carbonized lithium slag powder is as follows: first, carbonization pretreatment of the water-containing lithium slag is performed by using carbon dioxide, the carbonization time of the material is controlled to be 30 min, lithium oxide in the lithium slag reacts to generate lithium carbonate in the presence of water, then the lithium slag is dried by using 140°C waste heat, and then the lithium slag is ground by using a ball mill.

[0076] The fly ash is finely ground fly ash, and has performance indexes in accordance with the quality of grade II ash, and a 45 μm sieve residue of ≤3.0%.

[0077] The mineral powder is finely ground slag powder, and has a specific surface area of (650±20) m 2 / kg, and a 28d activity index of ≥105%.

[0078] Silica ash is a powder material with amorphous silica as the main component, which is obtained by collecting the dust discharged through the flue during the smelting of ferrosilicon or industrial silicon, SiO2 content ≥ 90.0%, specific surface area (BET method) ≥ 18 m 2 / g.

[0079] Gypsum is hard gypsum, wherein SO3 ≥ 48%, and the content of crystal water is ≤ 3.0%.

[0080] Dextrin is β-cyclodextrin with specific optical rotation = + (162 ± 2) °, and particle size distribution: 20.0-30.0 μm.

[0081] The corrosion-resistant and wear-resistant reinforcing material comprises, by weight percentage:

[0082] Steel slag powder: 30.0%,

[0083] Alunite: 60.0%,

[0084] Carborundum powder: 10.0%.

[0085] The steel slag powder is a steel slag micro-powder prepared by grinding the carbon dioxide gas-cooled steel slag, with D 50 ≤ 5.0 μm, and Blaine specific surface area (680 ± 20) m 2 / kg, and the content of iron oxide is ≥ 30%, and after the steel slag powder is cooled by carbon dioxide gas, the weight ratio of f-CaO is 2.5-4.0%, and the weight ratio of f-MgO is 2.0-4.0%.

[0086] Alunite is finely ground alunite, with the content of pure alunite ≥ 70%, the ratio of potassium to sodium ≥ 5.5, and the specific surface area (350 ± 20) m 2 / kg.

[0087] Carborundum powder is finely ground carborundum powder, with fineness 45 μm residue ≤ 15.0%.

[0088] The fiber is a mixed fiber composed of steel fiber and polypropylene fiber, with the steel fiber being 85.0% and the PVC fiber being 15.0% by weight percentage, the steel fiber being an alloy structural steel, the shape being longitudinal and straight with hooks at both ends, the surface having fine indentations, and the 700-grade steel fiber having a nominal length ≤ 20 mm. The polypropylene fiber has a length ≤ 15 mm and an equivalent diameter of 30 μm.

[0089] The water reducing agent is a polycarboxylic acid and melamine composite high-performance powdery water reducing agent, with the polycarboxylic acid water reducing agent being 50.0-75.0% and the melamine water reducing agent being 25.0-50.0% by weight percentage, and the water reducing rate being ≥ 25%.

[0090] The fine aggregate is a mixture of machine-made sand and carbonized steel slag, and the machine-made sand is 60.0% and the steel slag is 40.0% by weight percentage. The specific grain size of the machine-made sand is 5.0-6.0, the MB value is less than or equal to 1.0, the stone powder content is less than or equal to 10.0%, and the flaky particle content is less than or equal to 5.0%. The carbonized steel slag is a steel slag treated by carbon dioxide carbon sequestration, which eliminates the problem of poor stability, and the particle size range is 2.5-5 mm, and the Fe2O3 content is greater than or equal to 30%.

[0091] The coarse aggregate is a shaped artificial fine stone, with double grading, and the maximum particle size is less than or equal to 25.0 mm, the close-packed void ratio is 35.0-37.0%, and the irregular particle content is less than or equal to 3.0%.

[0092] A method for preparing a pipe segment made of long-life low-carbon ferrum aluminate cement concrete, comprising the following steps:

[0093] (1) The mold is coated with a release agent: the concrete pipe segment mold is sprayed with an oily release agent 12 hours in advance, and then sprayed with a water-based release agent after 2 hours;

[0094] (2) Concrete mixing preparation: the pipe segment is filled with ferrum aluminate cement concrete dry mixture into the concrete transport mixer, and the water content of single concrete is 150 kg, which is slowly stirred for 240 seconds, then quickly stirred for 90 seconds, and then placed for 120 seconds to obtain ferrum aluminate cement concrete for pipe segments, and the concrete out-of-machine slump is controlled to be 140-180 mm;

[0095] (3) Pipe segment concrete pouring: the stirred ferrum aluminate cement concrete is poured into the mold in three times, the first layer is poured to one-third of the thickness of the pipe segment, vibrated at 0.80-0.85 MPa for 180 seconds, and the surface floating slurry is scraped off; the second layer is poured to two-thirds of the thickness of the pipe segment, vibrated at 0.90-0.95 MPa for 120 seconds, and the surface floating slurry is scraped off; the third layer is poured to the top of the pipe segment, vibrated at 0.95-1.00 MPa for 100 seconds, and the excess concrete is scraped off; at the same time, a reduced size test piece is poured, and a temperature measuring sensor is embedded in the test piece to determine the demolding time;

[0096] (4) Pipe segment concrete curing: a layer of concrete curing agent is sprayed on the surface of the concrete, the amount of concrete curing agent is 0.15 kg / m 2 , a layer of plastic film is covered, the film is removed after 30 minutes, the concrete is checked whether it is close to initial setting, if it is close to initial setting, secondary tamping is carried out, then water is sprayed for moisture curing, then a plastic film is covered, and a cotton quilt is covered on the film for heat preservation and curing;

[0097] (5) Formwork stripping: when the internal temperature of the reduced-size test piece is reduced to 40℃ or lower and the temperature difference between the internal and external environments is 20℃ or lower, the cotton quilt and the film can be removed in sequence, the formwork is loosened, then the pipe piece is lifted out of the formwork by the suction cup and placed in water for normal temperature curing.

[0098] Example 2

[0099] A long-life low-carbon ferrite aluminate cement concrete, by weight, comprises:

[0100] Ferrite aluminate cement: 450 parts;

[0101] Non-autoclaved functional material: 90 parts;

[0102] Corrosion-resistant wear-resistant reinforcing material: 80 parts;

[0103] Fiber: 25 parts

[0104] Water reducing agent: 3 parts;

[0105] Fine aggregate: 640 parts;

[0106] Coarse aggregate: 950 parts.

[0107] The ferrite aluminate cement is a high-iron ferrite aluminate cement with a strength grade of 42.5 MPa or higher, and its Blaine specific surface area is (400±20) m 2 / kg; The cement clinker mineral phase for preparing the ferrite aluminate cement contains 45.0-55.0% anhydrous calcium sulphoaluminate, 15.0-25.0% dicalcium silicate and 30.0-35.0% iron phase solid solution by weight percentage, and the ferrite aluminate cement contains 10.0-12.0% magnetite.

[0108] The non-autoclaved functional material comprises, by weight percentage:

[0109] Lithium slag powder: 25.0%,

[0110] Fly ash: 40.0%,

[0111] Mineral powder: 25.0%,

[0112] Silica fume: 5.0%,

[0113] Gypsum: 4.5%,

[0114] Dextrin: 0.5%.

[0115] The lithium slag powder is a carbonized lithium slag powder with a specific surface area of (350±20) m 2 / kg, the preparation process of the carbonized lithium residue powder is that firstly, the water-containing lithium residue is carbonized by carbon dioxide, the carbonization time of the material is controlled within 35 minutes, the lithium oxide in the lithium residue reacts to form lithium carbonate in the presence of water, then the lithium residue is dried by using the waste heat of 120 DEG C, and then is ground by a ball mill.

[0116] The fly ash is finely ground ash, and the performance index meets the quality of grade II ash, and the 45 μm residue is less than or equal to 3.0%.

[0117] The mineral powder is finely ground slag powder, and the specific surface area is (650±20) m 2 / kg, and the 28d activity index is greater than or equal to 105%.

[0118] The silica ash is a powder material mainly composed of amorphous silicon dioxide, which is collected from the dust discharged from the flue during the smelting of ferrosilicon or industrial silicon, and the SiO2 content is greater than or equal to 90.0%, and the specific surface area (BET method) is greater than or equal to 18 m 2 / g.

[0119] The gypsum is hard gypsum, wherein, the SO3 is greater than or equal to 48%, and the crystal water content is less than or equal to 3.0%.

[0120] The dextrin is beta cyclodextrin, and the specific optical rotation is +(162±2) DEG, and the particle size distribution is 20.0-30.0 μm.

[0121] The corrosion-resistant and wear-resistant reinforcing material comprises, by weight percentage:

[0122] The steel slag powder: 40.0%,

[0123] The alunite: 40.0%,

[0124] The corundum powder: 20.0%.

[0125] The steel slag powder is a steel slag powder prepared by grinding the carbon dioxide gas-cooled steel slag, and the D 50 ≤5.0 μm, and the Blaine specific surface area is (680±20) m 2 / kg, the iron oxide content is greater than or equal to 30%, the weight ratio of f-CaO after the carbon dioxide gas cooling of the steel slag powder is 2.5-4.0%, and the weight ratio of f-MgO is 2.0-4.0%.

[0126] The alunite is finely ground alunite, the pure alunite content is greater than or equal to 70%, the potassium-sodium ratio is greater than or equal to 5.5, and the specific surface area is (350±20) m 2 / kg.

[0127] The corundum powder is finely ground gold steel sand powder, and the fineness 45 μm residue is less than or equal to 15.0%.

[0128] The fiber is a mixed fiber composed of steel fiber and polypropylene fiber, the steel fiber is 85.0% by weight, and the PVC fiber is 15.0% by weight. The steel fiber is an alloy structural steel, the shape is longitudinal straight and the two ends are hooked, the surface has fine and dense indentations, and the nominal length of 700-grade steel fiber is ≤20mm. The polypropylene fiber length is ≤15mm, and the equivalent diameter is 30μm.

[0129] The water reducing agent is a polycarboxylic acid and melamine composite high-performance powder water reducing agent, the polycarboxylic acid water reducing agent is 50.0-75.0% by weight, and the melamine water reducing agent is 25.0-50.0% by weight. The water-reducing rate is ≥25%.

[0130] The fine aggregate is a mixture of machine-made sand and carbonized steel slag, the machine-made sand is 70.0% by weight, and the steel slag is 30.0% by weight. The specific grain size of the machine-made sand is 5.0-6.0, the MB value is ≤1.0, the stone powder content is ≤10.0%, and the flaky particle content is ≤5.0%. The carbonized steel slag is a steel slag treated by carbon dioxide carbon sequestration, which eliminates the problem of poor stability, and the particle size range is 2.5-5mm, and the Fe2O3 content is ≥30%.

[0131] The coarse aggregate is a shaped artificial fine stone, three-level distribution, the maximum particle size is ≤25.0mm, the close-packed void ratio is 35.0-37.0%, and the irregular particle content is ≤3.0%.

[0132] A preparation method of a pipe segment made of long-life low-carbon ferrum aluminate cement concrete, comprising the following steps:

[0133] (1) The mold is coated with a release agent: the concrete pipe segment mold is sprayed with an oily release agent 12h in advance, and then sprayed with a water-based release agent after 2h interval;

[0134] (2) Concrete mixing preparation: the pipe segment is filled with ferrum aluminate cement concrete dry mixture into the concrete transport mixer, the water content of single concrete is 160kg, slow stirring for 300s, then fast stirring for 60s, and then standing for 120s, to obtain ferrum aluminate cement concrete for pipe segment, and the concrete out-of-machine slump is controlled at 140-180mm;

[0135] (3) Pipe segment concrete pouring: the stirred ferrum aluminate cement concrete is poured into the mold in three times, the first layer, one third of the thickness of the pipe segment is poured, vibrated at 0.80-0.85MPa air pressure for 180s, and the surface floating slurry is scraped off; the second layer, two thirds of the thickness of the pipe segment is poured, vibrated at 0.90-0.95MPa air pressure for 120s, and the surface floating slurry is scraped off; the third layer, the top of the pipe segment is poured, vibrated at 0.95-1.00MPa air pressure for 100s, and the excess concrete on the surface is scraped off; at the same time, a reduced size test piece is poured, a temperature measuring sensor is embedded in the test piece, and the demolding time is determined;

[0136] (4) Segment concrete curing: Spraying a layer of concrete curing agent on the surface of the concrete, the amount of concrete curing agent is 0.20 kg / m 2 , covering a layer of plastic film, after 30 min, the film is removed, and the concrete is checked whether it is close to initial setting, if it is close to initial setting, secondary troweling is carried out, then water is sprayed for moisture curing, then a plastic film is covered, and a cotton quilt is covered on the film for curing and heat preservation;

[0137] (5) Segment demolding: when the internal temperature of the reduced size test piece is reduced to below 40℃, and the temperature difference between the internal and external environment is lower than 20℃, the cotton quilt and the film are removed in sequence, the mold is loosened, then the segment is lifted out of the mold by the suction cup, and is placed in water for normal temperature curing.

[0138] Example 3

[0139] A long-life low-carbon ferrite aluminate cement concrete, by weight, comprising:

[0140] Ferrite aluminate cement: 420 parts;

[0141] Non-autoclaved functional material: 75 parts;

[0142] Corrosion-resistant and wear-resistant reinforcing material: 60 parts;

[0143] Fiber: 17.5 parts

[0144] Water reducing agent: 2.5 parts;

[0145] Fine aggregate: 670 parts;

[0146] Coarse aggregate: 1000 parts.

[0147] The ferrite aluminate cement is a high-iron ferrite aluminate cement with a strength grade of 42.5 MPa or more, and a Blaine specific surface area of (400±20) m 2 / kg; The cement clinker mineral phase for preparing the ferrite aluminate cement contains, by weight percentage, 45.0-55.0% of anhydrous calcium sulphoaluminate, 15.0-25.0% of dicalcium silicate, and 30.0-35.0% of iron phase solid solution, and the ferrite aluminate cement has a content of 10.0-12.0% of iron trioxide.

[0148] The non-autoclaved functional material comprises, by weight percentage:

[0149] Lithium slag powder: 30.0%,

[0150] Fly ash: 30.0%,

[0151] Mineral powder: 25.0%,

[0152] Silica fume: 5.0%,

[0153] Gypsum: 9.5%,

[0154] Dextrin: 0.5%.

[0155] Lithium slag powder is carbonized lithium slag powder, with a specific surface area of (350±20) m 2 / kg. The preparation process of the carbonized lithium slag powder is that firstly, the water-containing lithium slag is carbonized by carbon dioxide for 40 minutes to react lithium oxide in the lithium slag to form lithium carbonate in the presence of water, then the lithium slag is dried by using 130℃ waste heat, and then is ground by a ball mill.

[0156] Fly ash is finely ground fly ash, with performance indexes meeting the quality of grade II ash, and a 45μm sieve residue of ≤3.0%.

[0157] Slag powder is finely ground slag powder, with a specific surface area of (650±20) m 2 / kg, and a 28d activity index of ≥105%.

[0158] Silica fume is a powder material mainly composed of amorphous silicon dioxide, which is collected from the dust discharged through the flue during the smelting of ferrosilicon or industrial silicon, with a SiO2 content of ≥90.0% and a specific surface area (BET method) of ≥18m 2 / g.

[0159] Gypsum is hard gypsum, wherein SO3≥48%, and the content of crystal water is ≤3.0%.

[0160] Dextrin is β-cyclodextrin, with a specific optical rotation of +(162±2)°, and a particle size distribution of 20.0-30.0μm.

[0161] The corrosion-resistant and wear-resistant reinforcing material comprises, by weight percentage:

[0162] Steel slag powder: 35.0%,

[0163] Alunite: 50.0%,

[0164] Corundum powder: 15.0%.

[0165] Steel slag powder is steel slag powder prepared by grinding carbon dioxide gas-cooled steel slag, with a D 50 ≤5.0μm, a Blaine specific surface area of (680±20) m 2 / kg, and an iron oxide content of ≥30%. After the carbon dioxide gas cooling, the weight ratio of f-CaO is 2.5-4.0%, and the weight ratio of f-MgO is 2.0-4.0%.

[0166] Alunite is finely ground alunite, with a pure alunite content of ≥70%, a potassium-sodium ratio of ≥5.5, and a specific surface area of (350±20) m 2 / kg.

[0167] The emery powder is a fine emery powder, and the fineness 45μm residue is less than or equal to 15.0%.

[0168] The fiber is a mixed fiber composed of steel fiber and polypropylene fiber, and the steel fiber is 85.0% by weight, and the PVC fiber is 15.0% by weight. The steel fiber is an alloy structural steel, and the shape is longitudinal straight with hooks at both ends, and the surface has fine indentations. The nominal length of the 700-grade steel fiber is less than or equal to 20mm. The length of the polypropylene fiber is less than or equal to 15mm, and the equivalent diameter is 30μm.

[0169] The water reducing agent is a polycarboxylic acid and melamine composite high-performance powder water reducing agent, and the polycarboxylic acid water reducing agent is 50.0-75.0% by weight, and the melamine water reducing agent is 25.0-50.0% by weight. The water-reducing rate is greater than or equal to 25%.

[0170] The fine aggregate is a mixture of machine-made sand and carbonized steel slag, and the machine-made sand is 75.0% by weight and the steel slag is 25.0% by weight. The specific particle size of the machine-made sand is 5.0-6.0, the MB value is less than or equal to 1.0, the stone powder content is less than or equal to 10.0%, and the flaky particle content is less than or equal to 5.0%. The carbonized steel slag is a steel slag treated by carbon dioxide carbon sequestration, which eliminates the problem of poor stability, and the particle size range is 2.5-5mm, and the Fe2O3 content is greater than or equal to 30%.

[0171] The coarse aggregate is a shaped artificial fine gravel, and the maximum particle size is less than or equal to 25.0mm, the close-packed void ratio is 35.0-37.0%, and the irregular particle content is less than or equal to 3.0%.

[0172] A preparation method of a long-life low-carbon ferrum aluminate cement concrete pipe segment, comprising the following steps:

[0173] (1) The mold is coated with a release agent: the concrete pipe segment mold is sprayed with an oily release agent in advance 12h, and then sprayed with a water-based release agent after 2h interval;

[0174] (2) Concrete mixing preparation: the pipe segment is filled with ferrum aluminate cement concrete dry mixture into the concrete transport mixer, and the water consumption of single concrete is 155kg, and then slowly stirred for 270s, and then quickly stirred for 75s, and then placed for 120s, to obtain the ferrum aluminate cement concrete for pipe segment, and the concrete out of the machine slump is controlled in the range of 140-180mm;

[0175] (3) Segment concrete pouring: The mixed ferrite-aluminate cement concrete is poured into the mold for three times. For the first layer, one-third thickness of the segment is poured, vibrated at 0.80-0.85 MPa for 180 s, and the surface floating slurry is scraped off. For the second layer, two-thirds thickness of the segment is poured, vibrated at 0.90-0.95 MPa for 120 s, and the surface floating slurry is scraped off. For the third layer, the top of the segment is poured, vibrated at 0.95-1.00 MPa for 100 s, and the surface excess concrete is scraped off. At the same time, a reduced-size test piece is poured, and a temperature measuring sensor is embedded in the test piece to determine the demolding time.

[0176] (4) Segment concrete curing: A layer of concrete curing agent is sprayed on the surface of the concrete, the concrete curing agent is used in an amount of 0.18 kg / m 2 , a plastic film is covered, the film is removed after 30 min, and whether the concrete is close to initial setting is checked. If the concrete is close to initial setting, secondary troweling is performed, then water is sprayed for moisture curing, the plastic film is covered again, and a cotton quilt is covered on the film for temperature curing.

[0177] (5) Segment demolding: When the temperature in the reduced-size test piece is reduced to below 40℃, and the temperature difference between the inside and outside environment is lower than 20℃, the cotton quilt and the film are removed in sequence, the mold is loosened, then the segment is lifted out of the mold by a suction cup, and is placed in water for normal temperature curing.

[0178] According to GB / T 22082-2017 "Precast Concrete Lining Segment" and GB / T 50082-2009 "Standard for Long-Term Performance and Durability Test Methods of Ordinary Concrete", the performance of the long-life low-carbon ferrite-aluminate cement concrete segment is tested. The demolding strength is 40.0-45.0 MPa, the 28d compressive strength is 59.5-64.0 MPa, the impermeability grade is P20-P25, the 28d electric flux is 600-750C, the segment surface is free of penetrating cracks and non-penetrating cracks, and free of loose inclusions.

[0179] The above only describes the preferred embodiments of the present application, and is not used to limit the present application. Any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A long-life low-carbon aluminoferrite cement concrete, characterized in that, On a weight basis, it comprises: Ferroaluminate cement: 400-450 parts; No-steam curing functional materials: 60-90 parts; Corrosion-resistant and wear-resistant reinforcing material: 40-80 parts; Fiber: 10–25 parts; Water-reducing agent: 2-3 parts; Fine aggregate: 640-700 parts; Coarse aggregate: 950–1040 parts; The corrosion-resistant and wear-resistant reinforcing material, by weight percentage, comprises: Steel slag powder: 30.0%–40.0% Alum stone: 40.0%–60.0% Emery powder: 10.0%–20.0%; The steel slag powder mentioned is steel slag micro powder obtained by grinding carbon dioxide gas-cooled steel slag, and its D 50 ≤5.0μm, Blaine specific surface area is (680±20)m² 2 / kg, iron oxide content ≥30%, the steel slag powder is cooled by carbon dioxide gas. f- The CaO weight percentage is 2.5%–4.0%. f- The MgO weight percentage is 2.0–4.0%; the alunite is finely ground raw alunite, with a pure alunite content ≥70%, a potassium-to-sodium ratio ≥5.5, and a specific surface area of ​​(350±20) m². 2 / kg; the diamond powder mentioned is finely ground diamond powder with a fineness of ≤15.0% residue on a 45μm sieve; The fiber is a mixture of steel fiber and polypropylene fiber, with steel fiber accounting for 85.0-95.0% and PVC fiber accounting for 5.0-15.0% by weight. The steel fiber is alloy structural steel, with a longitudinally straight shape and hooks at both ends, and fine indentations on the surface. It is a grade 700 steel fiber with a nominal length ≤20mm. The polypropylene fiber has a length ≤15mm and an equivalent diameter of 30μm. The aforementioned steam-free curing functional material, by weight percentage, comprises: Lithium slag powder: 20.0%–30.0% Fly ash: 30.0%–40.0% Mineral powder: 20.0%–30.0% Silica fume: 5.0–10.0%, Gypsum: 5.0%–10.0% Dextrin: 0.5%; The lithium slag powder is carbonized lithium slag micro powder with a specific surface area of ​​(350±20) m2 / kg. The preparation process of carbonized lithium slag micro powder is as follows: first, the aqueous lithium slag is pretreated by carbon dioxide carbonization, and the carbonization time of the material is controlled at 30-50 min. The lithium oxide in the lithium slag reacts in the presence of water to generate lithium carbonate. Then, the lithium slag is dried using residual heat at 120-140℃ and then ground by ball mill.

2. The long-life low-carbon aluminoferrite cement concrete according to claim 1, characterized in that: The aforementioned ferroaluminate cement is a high-ferrophase ferroaluminate cement with a strength grade of 42.5 MPa or higher, and its Blaine specific surface area is (400±20) m². 2 / kg; the cement clinker for preparing the ferroaluminate cement contains, by weight percentage, 45.0-55.0% anhydrous calcium sulfoaluminate, 15.0-25.0% dicalcium silicate and 30.0-35.0% iron phase solid solution, and the ferroaluminate cement contains 10.0-12.0% ferric oxide.

3. The long-life low-carbon aluminoferrite cement concrete according to claim 1, characterized in that: The water-reducing agent is a high-performance powdered water-reducing agent composed of polycarboxylic acid and melamine. By weight percentage, the polycarboxylic acid water-reducing agent is 50.0-75.0%, the melamine water-reducing agent is 25.0-50.0%, and the water reduction rate is ≥25%.

4. The long-life low-carbon aluminoferrite cement concrete according to claim 1, characterized in that: The fine aggregate is a mixture of manufactured sand and carbide steel slag, with manufactured sand comprising 60.0-75.0% and steel slag comprising 25.0-40.0% by weight. The manufactured sand has a specific particle size of 5.0-6.0, an MB value ≤1.0, a stone powder content ≤10.0%, and a flaky particle content ≤5.0%. The carbide steel slag is steel slag treated with carbon dioxide to eliminate its poor stability, with a particle size range of 2.5-5.0 mm and an Fe2O3 content ≥30%. The coarse aggregate is shaped artificial high-quality crushed stone, a multi-grade aggregate with a maximum particle size ≤25.0 mm, a compacted packing porosity of 35.0-37.0%, and an irregular particle content ≤3.0%.

5. A method for preparing segments of long-life low-carbon aluminoferrite cement concrete according to any one of claims 1 to 4, characterized in that, Includes the following steps: (1) Apply release agent to the mold: spray an oil-based release agent on the concrete segment mold 12 hours in advance, and then spray a water-based release agent after an interval of 2 hours. (2) Concrete mixing and preparation: The dry mix of ferroaluminate cement concrete for pipe segments is loaded into the concrete transport mixer truck, water is added according to the formula, and the mixture is first slowly mixed for 240-300s, then quickly mixed for 60-90s, and then left to stand for 120s to obtain the ferroaluminate cement concrete for pipe segments. The slump of the concrete at the outlet is controlled at 140-180mm. (3) Segment concrete pouring: The mixed aluminate cement concrete is poured into the mold in three stages. The first layer is poured to one-third the thickness of the segment, and vibrated for 180s with a vibrating air pressure of 0.80~0.85MPa. The surface laitance is scraped off. The second layer is poured to two-thirds the thickness of the segment, and vibrated for 120s with a vibrating air pressure of 0.90~0.95MPa. The surface laitance is scraped off. The third layer is poured to the top of the segment, and vibrated for 100s with a vibrating air pressure of 0.95~1.00MPa. The excess concrete on the surface is scraped off. At the same time, a scaled-down specimen is poured. A temperature sensor is embedded inside the specimen to determine the demolding time. (4) Curing of segment concrete: Spray a layer of concrete curing agent on the concrete surface, cover it with a layer of plastic film, remove the film after 30 minutes, check whether the concrete is close to initial setting. If it is close to initial setting, perform a second troweling, then spray water to keep it moist and cured, then cover it with plastic film, and cover the film with a cotton quilt for heat preservation and curing. (5) Demolding of the tube segment: When the internal temperature of the reduced-size specimen drops below 40℃ and the temperature difference between the inside and outside environment is less than 20℃, the cotton quilt and film can be removed in sequence, the mold can be loosened, and then the tube segment can be lifted out of the mold with a suction cup and placed in water for room temperature curing.