Method for preparing low-carbon super-high early-strength and toughness cement-based material

Abstract

The application discloses a preparation method of low-carbon super-high early-strength toughness cement-based material, which comprises the following steps: adding densely-stacked cementitious materials, a hydration accelerator, a densifying agent, a water reducing agent and water into a mortar stirring pot, and stirring uniformly to obtain a slurry mixture; adding the obtained slurry mixture into densely-stacked quartz sand fine aggregate, and stirring uniformly to obtain a freshly-mixed mortar mixture; adding multi-stage mixed fibers into the freshly-mixed mortar mixture, and stirring uniformly to obtain a freshly-mixed fiber reinforced cement-based material; pouring the freshly-mixed fiber reinforced cement-based material into a plastic test mold, and performing vibration and compaction molding through a vibration table; covering a film on the surface of the compacted test piece, and placing the test piece in an insulation box in a room temperature environment; then, inserting an alternating current electrode into the end of the test piece, and performing direct alternating current rapid curing by using a voltage of 36V-48V; and after applying an electric field for 6-8 hours, the power is turned off; the method realizes the synergistic promotion of super-high early strength and super-high toughness, and also has excellent long-term mechanical properties.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of civil engineering materials, and particularly relates to a preparation method of low-carbon super-high early strength and toughness cement-based material. BACKGROUND

[0002] High-rise buildings and super high-rise buildings have appeared in many cities, and the construction efficiency is required to be significantly increased. In particular, for some repair projects, large-span bridges and nuclear power plants, etc., the super high performance cement-based material (UHPC) is usually required to realize rapid setting and hardening and has high early strength. The ordinary concrete cannot meet the requirements of modern large and complex building construction. Therefore, the cement-based material with super high strength, good bending performance, (super) high early strength and high toughness is one of the important requirements of modern engineering structures.

[0003] At present, the methods for improving the early strength include using early strength agent, fast hardening early strength cement, steam accelerated curing, microwave curing, etc. However, the steam curing is a surface heating method, which causes a large temperature difference between the inside and outside of the concrete during curing, causes serious thermal damage to the concrete, is not conducive to the development of the late strength of the concrete, and seriously affects the long-term durability of the concrete product. The early strength agent alone is difficult to achieve the expected target early strength requirement. The late strength of the fast hardening early strength cement often fails to meet the expectation or even decreases, especially for the super high early strength and toughness cement-based material, which is difficult to meet the requirements. Although there are many researches on the super high strength cement-based material at present, including reactive powder concrete (RPC), ultra high performance cement-based material (UHPC) and macro-defect-free cement (MDF), on the one hand, the cement and other cementitious materials are used in large quantities, and the carbon emission is large, and on the other hand, the early strength (1d age) of these new cement-based materials is usually between 50MPa and 80MPa, which still fails to meet the target requirement of super high early strength. SUMMARY

[0004] The purpose of the embodiment of the application is to provide a preparation method of low-carbon super high early strength and toughness cement-based material, which realizes the synergistic improvement of super high early strength and super high toughness, and also has excellent long-term mechanical properties.

[0005] The technical scheme adopted by the application is a preparation method of low-carbon super high early strength and toughness cement-based material, which is performed according to the following steps:

[0006] S1, the densely packed cementitious materials, a hydration accelerator, a densification agent, a water reducing agent and water are added into a mortar stirring pot, and are uniformly stirred to obtain a slurry mixture;

[0007] S2, the slurry mixture obtained in S1 is added into the densely packed quartz sand fine aggregate, and is uniformly stirred to obtain a freshly mixed mortar mixture;

[0008] S3, the new mixing mortar mixture obtained in S2 is added to multi-stage mixed fibers, and stirred uniformly to obtain a new mixing fiber reinforced cement-based material;

[0009] S4, the new mixing fiber reinforced cement-based material obtained in S3 is cast into a plastic test mold, and vibrated and compacted by a vibration table to form a compacted test piece;

[0010] S5, the surface of the compacted test piece in S4 is covered with a film, and placed in an incubator at room temperature for 2-3 hours, then an alternating current electrode is inserted into the end of the test piece, and direct alternating current rapid curing is performed at a voltage of 36-48V, and the power is turned off after 6-8 hours of electric field application;

[0011] S6, until 1d age, the test piece is taken out of the incubator, and the mechanical properties at 1d age are tested, and a low-carbon ultra-high early strength and toughness cement-based material is obtained.

[0012] Further, in S1, the cementitious material is composed of 45-55 parts by weight of ordinary Portland cement, 16-20 parts of silica fume, 20-23 parts of blast furnace granulated slag powder, 8-10 parts of zeolite powder, and 1-2 parts of nano-iron trioxide material, and the compactness of the cementitious material is not less than 0.74.

[0013] Further, the ordinary Portland cement is one of P.O 42.5, P.O 52.5, and P.I 42.5 cement;

[0014] The silica fume is silica fume with a silicon dioxide content of not less than 92%;

[0015] The blast furnace granulated slag powder is blast furnace granulated slag powder with an activity index of not less than S95;

[0016] The zeolite powder is natural clinoptilolite powder with an average particle size of not more than 10μm;

[0017] The nano-iron trioxide is γ-crystal type with an average particle size of 30-50nm and a content of ≥99.8%.

[0018] Further, the hydration accelerator is one or more of sodium sulfate, sodium carbonate, sodium bicarbonate, and sodium silicate, and the content of the hydration accelerator is 1-3% of the mass of the cementitious material;

[0019] The compacting agent is a mixture of high-carbon alcohol and polyether-modified silicone in a mass ratio of 1-2, and the dosage is 0.1-0.2% of the mass of water;

[0020] The water-reducing agent is a polycarboxylic acid-based powder high-performance water-reducing agent with a water-reducing rate of not less than 35%;

[0021] In the slurry mixture, the mass ratio of water to cementitious material is not more than 0.22.

[0022] Further, in the S2, the particle size of the quartz sand fine aggregate is 0.075-1.18 mm, and the packing density of the quartz sand fine aggregate is not less than 0.72; the mass ratio of the slurry mixture to the quartz sand fine aggregate is 1:(1-2).

[0023] Further, in the S3, the multi-level mixed fiber is composed of micro-fine steel fiber with a diameter of 0.18-0.2 mm and a length of 12-15 mm, carbon fiber with a diameter of 4-6 μm and a length of 0.5-1 mm, calcium sulfate whisker with a diameter of 2-4 μm and a length of 100-200 μm, and graphene with a thickness of 1-3 nm and a width of 0.5-3 nm.

[0024] Further, the mass ratio of the micro-fine steel fiber, the carbon fiber, the calcium sulfate whisker, and the graphene is 90:6:(3-2.5):(1-1.5).

[0025] Further, the micro-fine steel fiber is uniformly added to the freshly mixed mortar mixture through a screen, and the carbon fiber, the calcium sulfate whisker, and the graphene are added to the freshly mixed mortar mixture after being dispersed by ultrasonic dispersion or a dispersant.

[0026] Further, the multi-level mixed fiber accounts for not less than 1.8% of the total volume of the freshly mixed fiber reinforced cement-based material.

[0027] Further, the fluidity of the freshly mixed fiber reinforced cement-based material is between 160 and 200 mm.

[0028] In the step S3, the freshly mixed fiber reinforced cement-based material is filled from one end of the mold by using a single-side pouring method, the entire mold is filled by the flowability of the cement mortar, and the fiber direction is consistent with the main tensile stress direction.

[0029] The beneficial effects of the present application are:

[0030] (1) The present application mainly uses silicate cement, silica fume, and slag powder as traditional cementitious materials, and the cement content is 45%-55% of the total cementitious materials, which is reduced by 40%-50% compared with the existing super-high-strength cement-based material in which the cement content accounts for 75%-85%, thereby effectively reducing the carbon emission caused by cement.

[0031] (2) The present application uses commercially available high-water-content framework-like alkali earth metal aluminosilicate clinoptilolite powder which has a silicon-oxygen tetrahedron and an aluminum-oxygen tetrahedron structure, and uses a strong electrolyte hydration accelerator, and also uses nano Fe2O3 particles, so that the electric conductivity is enhanced by multiple parties, and the direct electric curing efficiency is effectively improved.

[0032] (3) The project adopts a full-scale multi-stage fiber hybrid reinforced system, each fiber has good bridging and conductivity, on the one hand, it works together with the alternating current field to enhance the curing efficiency of effective direct electric curing, on the other hand, it effectively improves the toughness of the cement-based material, reduces the internal damage of the cement-based material in the accelerated curing process, and ensures good mechanical properties.

[0033] (4) The project combines the target requirements of ultra-high early strength and ultra-high toughness, based on component design, combined with direct electric curing technology, and adopts self-insulation technology, synergistically improves the early strength of the cement-based material, and the energy consumption of the direct electric curing technology is reduced by more than 60% compared with the traditional steam curing technology, realizes the double goals of energy consumption reduction and performance improvement, and produces significant technical and economic benefits and ecological environmental effects.

[0034] (5) The ultra-high early strength and toughness cement-based material provided by the application has early (1d) strength ≥100MPa, toughness index I5 ≥4.0, and 28d age compressive strength ≥120MPa, and is simple, efficient and easy to operate, has low cost and low energy consumption, and is conducive to the popularization and application of the application. BRIEF DESCRIPTION OF DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the application or the prior art, the drawings needed to be used in the embodiments or the prior art description will be briefly introduced below. Obviously, the drawings in the following description are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creative labor.

[0036] Figure 1 It is the initial resistivity development test graph of the ultra-high early strength and toughness cement-based material under the accelerated curing effect of the electric field.

[0037] Figure 2 It is the temperature development test graph of the ultra-high early strength and toughness cement-based material under the accelerated curing effect of the electric field.

[0038] Figure 3 It is the compressive strength test graph of the ultra-high early strength and toughness cement-based material at different ages under the accelerated curing effect of the electric field.

[0039] Figure 4 It is the flexural strength test graph of the ultra-high early strength and toughness cement-based material at different ages under the accelerated curing effect of the electric field.

[0040] Figure 5 It is the accelerated curing process schematic diagram of the ultra-high early strength and toughness cement-based material under the electric field.

[0041] In the figure, 1 is an insulation box, 2 is a forming mold, 3 is an electrode, 4 is a temperature sensor, 5 is an alternating current power supply, and 6 is a temperature recorder. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0043] The present application mainly solves the problems of insufficient performance such as low early strength, low late strength increment rate and small toughness of the existing cement-based material, and the problems of high carbon emission, large shrinkage and high energy consumption of the steam accelerated curing mode caused by high cement content, and proposes a low-carbon super-high early strength and toughness cement-based material preparation method, which is compatible with a very low energy consumption direct alternating current field accelerated curing, and realizes the low-carbon super-high early strength and high toughness target from the aspects of new material composition and matching accelerated curing, thereby providing new material technical support for the engineering structure demand with the performance targets of super-high early strength and high toughness.

[0044] A low-carbon super-high early strength and toughness cement-based material preparation method is performed according to the following steps:

[0045] S1, the densely packed cementitious material, a hydration accelerator, a densifying agent, a water reducing agent and water are added into a mortar stirring pot, and are uniformly stirred to obtain a slurry mixture;

[0046] The cementitious material is composed of 45-55 parts by weight of ordinary portland cement, 16-20 parts by weight of silica fume, 20-23 parts by weight of blast furnace granulated slag powder, 8-10 parts by weight of zeolite powder, and 1-2 parts by weight of nano-iron trioxide particles, and the densely packed cementitious material has a compactness of not less than 0.74.

[0047] Preferably, the ordinary portland cement is one of P.O 42.5, P.O 52.5 and P.I 42.5 cement.

[0048] Preferably, the silica fume is silica fume with a silicon dioxide content of not less than 92%.

[0049] Preferably, the blast furnace granulated slag powder is blast furnace granulated slag powder with an activity index of not less than S95.

[0050] Preferably, the zeolite powder is natural clinoptilolite powder with an average particle size of not more than 10 μm.

[0051] The hydration accelerator is one or more than two of sodium sulfate, sodium carbonate, sodium bicarbonate and sodium silicate, and the hydration accelerator accounts for 1-3% of the mass of the cementitious material.

[0052] Preferably, the hydration accelerator is a sodium sulfate solution.

[0053] Preferably, the hydration accelerator is prepared at least 24 hours in advance and stored in a sealed environment at a temperature of (20-25) °C.

[0054] The densifier is a mixture of high-carbon alcohol and polyether-modified silicone in a mass ratio of 1-2, and the dosage is 0.1-0.2% of the mass of water.

[0055] Preferably, the densifier is a mixture with a mixing ratio of 1.5.

[0056] The water-reducing agent is a polycarboxylic acid-based powder high-performance water-reducing agent with a water-reducing rate of not less than 35%.

[0057] Preferably, in the paste mixture, the mass ratio of water to cementitious material (water-cement ratio) is not more than 0.22.

[0058] S2, the paste mixture obtained in S1 is added to the tightly packed quartz sand fine aggregate and mixed to obtain a freshly mixed mortar mixture;

[0059] The particle size of the quartz sand fine aggregate is in the range of 0.075-1.18 mm, and the packing density of the quartz sand fine aggregate is not less than 0.72.

[0060] Preferably, the mass ratio of the paste mixture to the quartz sand fine aggregate is 1:(1-2).

[0061] S3, the freshly mixed mortar mixture obtained in S2 is added to the multi-level mixed fiber and stirred to obtain a freshly mixed fiber-reinforced cement-based material;

[0062] The multi-level mixed fiber is composed of micro steel fiber (diameter 0.18-0.2 mm, length 12-15 mm), carbon fiber (diameter 4-6 μm, length 0.5-1 mm), calcium sulfate whisker (2-4 μm, length 100-200 μm), and graphene (1-3 nm thick, 0.5-3 nm wide).

[0063] Further, the mass ratio of the micro steel fiber, carbon fiber, calcium sulfate whisker, and graphene is 90:6:(3-2.5):(1-1.5).

[0064] Specifically, the micro steel fiber is uniformly added to the freshly mixed mortar mixture through a screen, and the carbon fiber, calcium sulfate whisker, and graphene are added to the freshly mixed mortar mixture after being dispersed by ultrasonic dispersion or a dispersant, which is beneficial to the uniform dispersion of the fiber and filler in the test specimen and prevents agglomeration.

[0065] The multi-level mixed fiber accounts for not less than 1.8% of the total volume of the freshly mixed fiber-reinforced cement-based material.

[0066] The fluidity of the fresh fiber reinforced cementitious material is between 160mm and 200mm. The larger fluidity is beneficial to the compaction of the concrete.

[0067] Further, the fresh fiber reinforced cementitious material in step S3 is filled from one end of the mold by using the single-side pouring method, and the whole mold is filled by the fluidity of the cement mortar, which is beneficial to the directional arrangement of the fibers, makes the conductive path constructed by the fibers more complete, and on the other hand, the fiber direction is consistent with the main tensile stress direction, which is beneficial to the improvement of the toughness of the concrete.

[0068] S4, pouring the fresh fiber reinforced cementitious material obtained in S3 into a plastic test mold, and using a vibrating table with a vibration frequency of 50Hz and a vibration amplitude of 2-4mm to vibrate and compact;

[0069] S5, covering the surface of the compacted test piece in S4 with a film, and placing it in a heat preservation box at room temperature for 2-3 hours, then inserting an alternating current electrode into the end of the test piece, and using a voltage of 36V-48V to perform direct alternating current rapid curing, and the power is turned off after 6-8 hours of electric field application;

[0070] S6, until 1d age, the test piece is taken out of the heat preservation box, and the mechanical properties at 1d age are tested, and the low-carbon ultra-high early strength toughness cementitious material is obtained.

[0071] The low-carbon ultra-high early strength toughness cementitious material has a 1d compressive strength ≥100MPa (the pressure area is 16cm 2 ), and a 1d bending toughness index I5 ≥4.0.

[0072] The beneficial effects of the present application are verified by the following examples.

[0073] In the following examples and comparative examples, the Portland cement used is P·I 42.5 cement; the silica fume is Ekken 940 grade microsilica powder; the blast furnace granulated slag powder is S 95 grade water-quenched granulated blast furnace slag produced by Pingxiang Iron and Steel Factory New Material Co., Ltd.; the zeolite powder is 1250 mesh powdered natural clinoptilolite powder; the nano ferric oxide is I grade (particle size 35±5nm) nano Fe2O3; the water reducing agent is SD-600P-S type polycarboxylic acid superplasticizer, and the hydration accelerator is sodium sulfate solution. The compacting agent is polyether modified silicone.

[0074] This example is directed to the early mechanical property evaluation of the ultra-high performance concrete under the action of electric field accelerated curing after the compacted cementitious material and the hydration accelerator are added. Comparative examples 1-2 are carried out according to the following steps:

[0075] 1, mix each group of cement mortar

[0076] (1) The mixing ratio of the super high performance concrete as the comparative example is shown in Table 1

[0077] Table 1 Raw material ratio per cubic meter of the super high performance concrete (kg / m 3 )

[0078]

[0079] 2. The preparation method of the super high performance concrete as the comparative example comprises the following steps:

[0080] S1. The cementitious material system in dense packing, water reducing agent and water are added into the mortar mixing pot together, and are stirred uniformly to obtain a slurry mixture.

[0081] S2. The mixture obtained in step one is added into the fine aggregate of quartz sand in dense packing, and is stirred uniformly to obtain a freshly mixed mortar mixture.

[0082] S3. The mortar obtained in step two is added into the multi-stage mixed fiber, and is stirred uniformly to obtain a freshly mixed fiber reinforced cementitious material.

[0083] S4. The freshly mixed fiber reinforced cementitious material obtained in step three is cast into a plastic test mold, wherein the test mold is composed of a forming mold 2, a pair of electrodes 3 and a temperature sensor 4 inserted into the bottom, and a vibrating table with a vibration frequency of 50 Hz and an amplitude of 2-4 mm is used for vibrating and compacting the forming. Figure 5

[0084] S5. The surface of the compacted test piece in step four is covered with a film, and is placed in a heat preservation box at room temperature for 2-3 hours, then an alternating current electrode is inserted into the end of the test piece, and direct alternating current rapid curing is carried out at a voltage of 36-48 V, and the power is turned off after 6-8 hours of electric field application, wherein the heat preservation box 1, the alternating current power supply 5 and the temperature recorder 6 are shown in Figure 5

[0085] S6. To 1d age, the test piece is taken out of the heat preservation box, and the mechanical properties at 1d age are tested, and the low-carbon super high early strength and toughness cementitious material can be obtained.

[0086] (2) The mixing ratio of the super high performance concrete as the examples 1-5 of the application is shown in Table 2

[0087] Table 3 Raw material ratio per cubic meter of the super high performance concrete (kg / m 3 )

[0088]

[0089] 3. The preparation method of the super high performance concrete comprises the following steps:

[0090] ​​S1The cementitious material system in close packing, hydration accelerator, densifier, water reducing agent and water are added into the mortar mixing pot and stirred uniformly to obtain a slurry mixture.

[0091] S2The slurry mixture obtained in step one is mixed with fine aggregate in close packing to obtain a freshly mixed mortar mixture.

[0092] S3The freshly mixed mortar mixture obtained in step two is mixed with multi-level fibers to obtain a freshly mixed fiber reinforced cementitious material.

[0093] S4The freshly mixed fiber reinforced cementitious material obtained in step three is cast into a plastic test mold, wherein the test mold is composed of a forming mold 2, a pair of electrodes 3 and a temperature sensor 4 inserted into the bottom, and a vibrating table with a vibration frequency of 50 Hz and an amplitude of 2-4 mm is used for vibration compaction molding. Figure 5

[0094] S5The surface of the compacted test piece in step four is covered with a film, and then placed in an incubator at room temperature for 2-3 hours. Then, an alternating current electrode is inserted into the end of the test piece, and direct alternating current rapid curing is carried out at a voltage of 36-48 V. The power is turned off after 6-8 hours of electric field application, wherein the incubator 1, alternating current power supply 5 and temperature recorder 6 are shown in the figure. Figure 1

[0095] S6To 1d age, the test piece is taken out of the incubator, and the mechanical properties at 1d age are tested, i.e. the low-carbon ultra-high early-strength toughness cementitious material is obtained.

[0096] Table 3 Test results of the mechanical properties of the super high performance concrete of Comparative Example 1

[0097]

[0098] Table 4 Test results of the mechanical properties of the super high performance concrete of Examples 1-5

[0099]

[0100] Figure 2 The test results show that the addition of the hydration accelerator increases the concentration of the electrolyte solution inside the concrete and increases the number of free-moving ions, and the synergistic effect with the full-scale multi-level conductive fiber effectively reduces the initial resistivity of the test piece in the concrete.

[0101] Figure 3 The test results show that due to the construction of an excellent conductive network inside the concrete, the heating efficiency of the concrete is improved during direct electric curing in an electric field, and the internal temperature of the concrete can reach more than 60℃, which is beneficial to accelerate the hydration of the cementitious material. ​​

[0102] Figure 4 and ​ The test results show that firstly, the addition of natural clinoptilolite powder and nano-iron trioxide effectively improves the early strength of the test piece and increases the toughness of the test piece. By reasonably designing the dense packing of the cementitious material system, the hydration accelerator, the densification agent, and the electric field accelerated curing, the hydration degree of the cementitious material is significantly improved, and the early mechanical properties of the concrete are improved. Due to the synergistic effect of the multi-level fibers, the toughness of the concrete is improved, and the bending toughness index of 1d is increased by about 50-70%. At the same time, under the action of electric field curing, the hydration degree of the dense packing of the cementitious material system is improved, and more C-S-H gel is generated, so that the mechanical properties of the concrete are still stably increased, and the 28d compressive strength of the concrete is increased by about 28-40%, and the flexural strength of the concrete is increased by about 35-60%. By adding the hydration accelerator and the full-scale multi-level conductive fiber and assisting the electric field accelerated curing, the toughness of the cement-based material is greatly enhanced, the early strength of the concrete is improved, and a stable growth of the late strength is provided.

[0103] In summary, the low-carbon ultra-high early strength and toughness cement-based material provided by the present application can provide new material technical support for high-demand rapid repair engineering construction and engineering structure requirements with ultra-high early strength and high toughness performance targets.

[0104] Each embodiment in the specification is described in a related manner, and the same and similar parts between each embodiment can be referred to each other. Each embodiment focuses on the difference from other embodiments. Especially, for the system embodiment, since it is basically similar to the method embodiment, the description is relatively simple, and the related parts can refer to the part of the method embodiment.

[0105] The above only describes the preferred embodiments of the present application and is not used to limit the protection scope of the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A method for preparing a low-carbon ultra-high early-strength and toughness cementitious material, characterized in that, According to the following steps: S1, the dense packing of cementitious materials and hydration accelerator, densification agent, water reducing agent and water are added into the mortar mixing pot, stirring evenly to get the slurry mixture; S2, the slurry mixture obtained in S1 is added to the tight packing of quartz sand fine aggregate and stirred together, stirring evenly to get the fresh mortar mixture; S3, the fresh mortar mixture obtained in S2 is added to the multi-stage mixed fiber, stirring evenly to get the fresh fiber reinforced cementitious material; S4, the fresh fiber reinforced cementitious material obtained in S3 is filled from one end of the mold by using single side casting method, and is vibrated and compacted into the plastic test mold by using the vibrating table; S5, the surface of the compacted test piece in S4 is covered with film, and is placed in the incubator at room temperature for 2-3 hours, then the alternating current electrode is inserted into the end of the test piece, and the direct alternating current rapid curing is carried out by using 36V-48V voltage, and the power is turned off after 6-8 hours of electric field application; S6, until 1d age, the test piece is taken out from the incubator, and the mechanical properties of 1d age are tested, so as to obtain the low-carbon ultra-high early strength toughness cementitious material; In S1, the cementitious material is composed of 45-55 parts of ordinary Portland cement or P.I 42.5 Portland cement, 16-20 parts of silica fume, 20-23 parts of blast furnace granulated slag powder, 8-10 parts of zeolite powder, and 1-2 parts of nano ferric oxide material, and the tight packing density of the cementitious material is not less than 0.74; The hydration accelerator is one or more of sodium sulfate, sodium carbonate, sodium bicarbonate and sodium silicate, and the content of the hydration accelerator is 1%-3% of the mass of the cementitious material; The densification agent is a mixture of high carbon alcohol and polyether modified silicone with a mass ratio of 1-2, and the content is 0.1-0.2% of the mass of water; The water reducing agent is a polycarboxylic acid type powder high performance water reducing agent, and the water reducing rate is not less than 35%; In the slurry mixture, the mass ratio of water to cementitious material is not more than 0.22; In S3, the multi-stage mixed fiber is composed of micro-fine steel fiber with a diameter of 0.18-0.2mm and a length of 12-15mm, carbon fiber with a diameter of 4-6μm and a length of 0.5-1mm, calcium sulfate whisker with a diameter of 2-4μm and a length of 100-200μm, and graphene with a thickness of 1-3nm and a width of 0.5-3nm.

2. The method of producing low carbon ultra-high early-strength ductile cementitious material according to claim 1, characterized in that, The ordinary Portland cement is one of P.O 42.5 and P.O 52.5 cement; The silica fume is silica fume with a silicon dioxide content of not less than 92%; The blast furnace granulated slag powder is blast furnace granulated slag powder with an activity index of not less than S95; The zeolite powder is natural clinoptilolite powder with an average particle size of not more than 10μm; The nano ferric oxide is γ crystal type with an average particle size of 30-50nm and a content of ≥ 99.8%.

3. The method of producing low carbon ultra-high early-strength ductile cementitious material according to claim 1, characterized in that, In S2, the particle size of the quartz sand fine aggregate is 0.075-1.18mm, and the packing density of the quartz sand fine aggregate is not less than 0.72; the mass ratio of the slurry mixture to the quartz sand fine aggregate is 1:(1-2).

4. The method of producing low carbon ultra-high early-strength ductile cementitious material according to claim 1, characterized in that, The mass ratio of the micro steel fiber, carbon fiber, calcium sulfate whisker and graphene is 90:6:(3~2.5):(1~1.5).

5. The method of producing low carbon ultra-high early-strength ductile cementitious material according to claim 1, characterized in that, The micro steel fiber is uniformly added into the fresh mortar mixture through a screen, and the carbon fiber, calcium sulfate whisker and graphene are added into the fresh mortar mixture after being dispersed by ultrasonic or a dispersing agent.

6. The method of producing low carbon ultra-high early-strength ductile cementitious material according to claim 1, characterized in that, The total volume of the multi-level mixed fiber in the fresh fiber reinforced cement-based material is not less than 1.8%.

7. The method of producing low carbon ultra-high early-strength ductile cementitious material according to claim 1, characterized in that, The fluidity of the fresh fiber reinforced cement-based material is between 160mm and 200mm.

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