Ultra-high performance concrete based on alite-belite-calcium sulphoaluminate cement and preparation method thereof

Abstract

The invention discloses ultra-high performance concrete based on alite-belite-calcium sulphoaluminate cement and a preparation method of the ultra-high performance concrete. The ultra-high performance concrete is prepared from 550-800 parts of alite-belite-calcium sulphoaluminate cement; 100 to 300 parts of an active mineral admixture; 100 to 200 parts of silica fume; 30 to 70 parts of silicon dioxide powder; 900 to 1300 parts of quartz sand; 120 to 250 parts of steel fiber; 15 to 35 parts of a water reducing agent; 130-180 parts of water; and 0-30 parts of an optional component activated aluminum oxide micro powder. According to the invention, the micro-expansion characteristic of calcium sulphoaluminate (CSA) in the ABY cement is fully utilized to effectively compensate shrinkage cracking, the quick-setting characteristic of the cement is well matched with the retarding effect of the polycarboxylic acid water reducer, the mineral admixture plays a synergistic effect of filling and activity, the dependence on high-temperature maintenance is obviously reduced by the high hydration activity of ABY, and the high-temperature curing performance of the cement is greatly improved. The UHPC with excellent volume stability, high early and later strength and good constructability is obtained.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an ultra-high performance concrete (UHPC) and its preparation method, and more particularly to an ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement (ABY cement) and its preparation method. Background Technology

[0002] Ultra-high performance concrete (UHPC), with its superior compressive strength (GB / T 31387—2025 ≥100MPa), excellent toughness, ultra-low permeability, and outstanding durability, has shown great application potential in important fields such as bridge engineering, building curtain walls, military protection, and maintenance and reinforcement. However, UHPC also faces significant challenges in material composition and performance realization. To achieve ultra-high strength and a dense microstructure, UHPC typically employs an extremely low water-cement ratio (usually ≤0.20) and an extremely high amount of cementitious materials (usually >800kg / m³). This compositional characteristic makes it difficult to control its fluidity and workability during the fresh mixing stage. More importantly, it is prone to severe autogenous shrinkage in the early hardening stage, accompanied by significant drying shrinkage in the later stage. The accumulated tensile stress inside can easily trigger microscopic and even macroscopic cracking, seriously threatening the long-term performance and durability of the structure.

[0003] To mitigate shrinkage cracking and meet the requirements for rapid early strength development, traditional OPC-based UHPC generally relies on high-temperature steam curing or high-temperature heat curing processes. These stringent curing conditions not only significantly increase production energy consumption and costs, limiting the application of UHPC in scenarios requiring on-site casting, large and complex components, or construction in low-temperature environments, but also increase the complexity of process control. Simultaneously, the relatively low early hydration activity of OPC makes it difficult to quickly achieve sufficient early strength under normal temperature curing, further reinforcing the reliance on heat curing.

[0004] Regarding material composition compatibility, high-efficiency water-reducing agents (especially polycarboxylate-based water-reducing agents) are crucial for achieving high fluidity in UHPC with low water-cement ratios. However, there is a certain contradiction between the retarding requirements of water-reducing agents in OPC-based systems and their hydration characteristics, sometimes requiring adjustments to the water-reducing agent formulation or the addition of additional retarding components. Furthermore, although adding mineral admixtures such as fly ash and slag to OPC-based UHPC can improve workability, reduce heat of hydration, and enhance later-stage strength, their contribution to early-stage strength in ultra-low water-cement ratio, high-density systems is relatively limited, and their mechanisms of action (such as activation and filling effects) in such demanding systems are not yet fully understood.

[0005] Therefore, developing a novel UHPC system that can effectively improve volume stability (especially shrinkage cracking), reduce dependence on harsh heat curing, be well compatible with existing high-efficiency admixtures, and fully leverage the synergistic effect of mineral admixtures is of great significance for broadening the application range of UHPC, reducing production costs, and improving engineering reliability. Summary of the Invention

[0006] Purpose of the invention: The technical problem to be solved by the present invention is to address the shortcomings of the prior art by providing an ultra-high performance concrete (UHPC) based on alite-belite-calcium sulfoaluminate cement (ABY cement) and its preparation method, aiming to overcome the deficiencies of traditional silicate cement (OPC) based UHPC in terms of volume stability (autogenous shrinkage and drying shrinkage), dependence on harsh heat curing, compatibility with high-efficiency water-reducing agents, and efficient synergistic utilization of mineral admixtures.

[0007] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0008] An ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement, comprising the following components by weight per cubic meter:

[0009] 550-800 parts of Alite-Belit-Calcium Sulfoaluminate Cement (ABY Cement);

[0010] 100-300 parts of active mineral admixture;

[0011] 100-200 parts silica fume;

[0012] 30-70 parts of silica powder;

[0013] All four of these can be used together as cementing materials;

[0014] 900-1300 parts of quartz sand;

[0015] 120-250 parts steel fiber;

[0016] 15-35 parts of water-reducing agent;

[0017] 130-180 parts water;

[0018] And optional component: 0-30 parts of activated alumina micro powder.

[0019] This invention utilizes the micro-expansion characteristics of calcium sulfoaluminate (CSA) in ABY cement to compensate for shrinkage, leverages its high early-stage hydration activity to reduce the need for heat curing, and utilizes its rapid-setting characteristics to achieve good compatibility with the retarding effect of existing polycarboxylate superplasticizers. It also promotes the filling and synergistic effect of mineral admixtures such as fly ash and slag in the system, thereby realizing a UHPC material that has excellent volume stability, high early and late strength, good workability, lower curing requirements, and better economic efficiency.

[0020] Specifically, the mineral phase composition of the aforementioned Alite-Belit-Calcium Sulfoaluminate cement, by mass percentage, includes C3S: 30-50%, C2S: 30-50%, C4A3S: 10-20%, C4AF: 0-5%, and CaSO4: 0-5%. It can be prepared by referring to the method disclosed in Chinese Patent CN116768505A.

[0021] The ABY cement is the core component of the cementitious system. Its key role is to provide calcium sulfoaluminate (CSA) minerals to impart micro-expansion to the system, and allite (C3S) and belite (C2S) minerals to provide high strength and rapid setting and high activity characteristics.

[0022] Specifically, the active mineral admixture is one or a combination of two of fly ash and granulated blast furnace slag; its dosage is 10% to 35% of the total mass of the cementitious materials.

[0023] The incorporation of active mineral admixtures (fly ash and / or slag) mainly utilizes their micro-aggregate filling effect and potential pozzolanic activity to synergistically optimize the paste density and long-term strength development with ABY cement.

[0024] In this invention, the silica fume is used to further fill micropores, improving the density and early strength of the slurry. The quartz sand, as a fine aggregate, is crucial for achieving high bulk density through gradation and particle size control. Preferably, the maximum particle size of the quartz sand is no greater than 0.6 mm.

[0025] In this invention, the steel fibers are used to significantly improve the toughness and crack resistance of UHPC. Preferably, the aspect ratio of the steel fibers is 10~15 / 0.2.

[0026] Preferably, the water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent, and its dosage is 1.5% to 3.0% of the total mass of the cementitious materials. The polycarboxylate-based high-efficiency water-reducing agent is used to ensure excellent workability and fluidity of fresh concrete at extremely low water-cement ratios. The rapid setting characteristics of ABY cement and the retarding effect of the polycarboxylate water-reducing agent are well matched in time, ensuring controllable setting time.

[0027] Preferably, the water-cement ratio used in mixing concrete is controlled within the range of 0.14 to 0.20, which is the basis for achieving ultra-high performance.

[0028] Furthermore, the activated alumina micro powder is an optional component, mainly used to further regulate the hydration process and expansion characteristics of CSA.

[0029] Furthermore, the present invention also provides a method for preparing the above-mentioned ultra-high performance concrete, comprising the following steps:

[0030] S1. Dry material premixing: Add Alite-Belit-Calcium Sulfoaluminate cement, active mineral admixtures, silica fume, silica powder, quartz sand and optional active alumina micro powder into a mixer and dry mix until the materials are uniform.

[0031] S2. Mix 70% to 85% of the total water volume with the water-reducing agent to form a solution; while the mixer is running, slowly and evenly add the solution to the dry material in step S1, and continue stirring to form a slurry;

[0032] S3. Keep the mixer running and evenly and disperse the steel fibers into the slurry obtained in step S2. Continue to stir to make the steel fibers evenly distributed.

[0033] S4. Slowly add the remaining 15% to 30% of water and continue stirring until a homogeneous mixture with good flowability and cohesiveness and no water separation is obtained.

[0034] S5. Molding and Curing: Pour the mixture into the mold, vibrate to compact it, cover with a film to prevent moisture evaporation, and cure.

[0035] Preferably, the entire mixing process in steps S1 to S4 should be carried out using a planetary mixer or a high-speed shear mixer, and the total mixing time should be controlled within 8 to 15 minutes.

[0036] Preferably, in step S5, the temperature of the curing is not higher than 30°C, and the curing is preferably carried out under standard curing conditions (temperature 20±2°C, relative humidity ≥95%) or natural conditions.

[0037] Thanks to the high early-age activity of ABY cement, the UHPC can achieve excellent early and late-age strength development under normal temperature curing conditions without the need for high-temperature steam curing or high-temperature heat curing.

[0038] Compared with the prior art, the present invention has the following beneficial effects:

[0039] First, the synergistic enhancement effect: This invention creatively utilizes alite-belite-calcium sulfoaluminate cement as the main cementing material. Specifically, calcium sulfoaluminate minerals hydrate to form ettringite, providing excellent early strength and growth rate; alite and belite minerals hydrate to form CSH gel, providing stable growth in later strength. The two work synergistically to form a dense microstructure with high-strength CSH gel as the framework and expansive ettringite crystals as the filler, achieving a perfect balance between early and later strength.

[0040] Second, it effectively improves volume stability and reduces the risk of shrinkage cracking: This invention makes full use of the hydration micro-expansion characteristics of calcium sulfoaluminate (CSA) mineral components in Alite-Belit-Calcium Sulfoaluminate Cement (ABY Cement). This characteristic can effectively compensate for the autogenous shrinkage and early drying shrinkage caused by the extremely low water-cement ratio and high cementitious material content of ultra-high performance concrete (UHPC), significantly alleviate the internal stress and cracking tendency caused by this, and improve the long-term durability and dimensional stability of UHPC structures.

[0041] Third, it has good compatibility with existing high-efficiency water-reducing agents (especially polycarboxylate-based ones): The inherent rapid setting hydration characteristics of ABY cement and the retarding effect of polycarboxylate-based water-reducing agents are inherently consistent in terms of time requirements; this compatibility allows the present invention to directly and effectively use existing mature polycarboxylate-based water-reducing agent products in the preparation process, without the need to develop new retarding water-reducing agents or make complex formula adjustments, simplifying the process and reducing costs, and ensuring good workability and controllable setting time of fresh concrete.

[0042] Fourth, fully leverage the synergistic effect of mineral admixtures to optimize early and late performance: In the ABY cement system, the addition of mineral admixtures such as fly ash and slag exhibits excellent synergistic effects; the pozzolanic activity of fly ash continues to play a role in the later stage, complementing the high strength provided by ABY cement in the early stage, and jointly promoting the balanced development of the overall mechanical properties (including compressive and flexural strength) of UHPC; at the same time, the micro-aggregate filling effect of the admixtures further optimizes the density of the paste structure, which is conducive to improving the long-term performance and durability of UHPC. Although its detailed mechanism of action is still under investigation, the actual effect is significant.

[0043] Fifth, it significantly reduces reliance on harsh heat curing: Compared to traditional silicate cement (OPC) based UHPC, ABY cement has significantly higher early hydration activity, enabling it to rapidly generate a large amount of strength skeleton under normal temperature and / or low temperature curing conditions. This characteristic effectively improves the bottleneck problem that traditional silicate cement UHPC usually has to rely on high-temperature steam curing or high-temperature heat curing to meet early high strength indicators, broadens the application scenarios of UHPC (such as on-site casting, winter construction, large and complex components, etc.), and helps to reduce energy consumption and production costs.

[0044] Sixth, good process compatibility: The preparation method provided by this invention does not require special equipment, is fully compatible with existing UHPC production processes, and is easy to realize large-scale industrial production and application. Attached Figure Description

[0045] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments, and the advantages of the present invention in the above and / or other aspects will become clearer.

[0046] Figure 1 This is a schematic diagram of the preparation process of the ultra-high performance concrete described in this invention.

[0047] Figure 2 This is a comparison curve of the autogenous shrinkage over time of the ultra-high performance concrete (UHPC) prepared in Examples 1-3 of this invention and the comparative example under standard curing conditions (20±2℃).

[0048] Figure 3 This is a comparison curve of the drying shrinkage of ultra-high performance concrete (UHPC) prepared in Examples 1-3 of this invention and the comparative example under standard curing conditions (20±2℃) over time.

[0049] Figure 4 This is a bar chart comparing the compressive strength of Embodiments 1, 2, and 3 of the present invention and the comparative examples (Group A standard curing and Group B steam curing) at 3 days and 28 days.

[0050] Figure 5 This is a bar chart comparing the flexural strength at 3 days and 28 days for Embodiments 1, 2, and 3 of the present invention and the comparative examples (Group A, standard curing; Group B, steam curing).

[0051] Figure 6 This is a schematic diagram illustrating the synergistic effects of the main components in the ABY cement-based UHPC of this invention. Detailed Implementation

[0052] The present invention can be better understood from the following embodiments.

[0053] In the following examples, the allit-belit-calcium sulfoaluminate cement (ABY cement) used was prepared according to the method disclosed in CN116768505A. The mineral phase composition, by mass percentage, includes C3S: 30~50%, C2S: 30~50%, C4A3S: 10~20%, C4AF: 0~5%, and CaSO4: 0~5%.

[0054] Grade I fly ash is produced by Rongfeng New Materials, containing 43% SiO2, 24% Al2O3, and 5.7% CaO. Granulated blast furnace slag is produced by Henan Jinrun New Materials, containing 33.1% SiO2, 39.3% CaO, 15% Al2O3, 9.9% MgO, and 1.9% SO3. Silica fume is produced by Henan Jinrun New Materials, containing 96.1% SiO2. Silica powder is produced by Chunhui Nanomaterials, and is 1-micron pure silica powder. Quartz sand is self-prepared river sand. Steel fiber is copper-plated steel fiber produced by Zhongxiang Engineering Materials. Polycarboxylate superplasticizer is 904BY type polycarboxylate superplasticizer produced by Subote New Materials.

[0055] In the following examples, the compressive strength and flexural strength were measured according to the GB / T 17671-2021 standard.

[0056] Self-shrinkage properties were determined according to GB / T 33460-2016 standard, and drying shrinkage properties were determined according to GB / T 751-2021 standard.

[0057] Combination Figure 1 The preparation process of ultra-high performance concrete based on Alite-Belit-Calcium Sulfoaluminate cement in this invention is as follows:

[0058] S1. Dry material premixing: Add Alite-Belit-Calcium Sulfoaluminate cement, active mineral admixtures, silica fume, silica powder, quartz sand and optional active alumina micro powder into a mixer and dry mix until the materials are uniform.

[0059] S2. Mix 70% to 85% of the total water volume with the water-reducing agent to form a solution; while the mixer is running, slowly and evenly add the solution to the dry material in step S1, and continue stirring to form a slurry;

[0060] S3. Keep the mixer running and evenly and disperse the steel fibers into the slurry obtained in step S2. Continue to stir to make the steel fibers evenly distributed.

[0061] S4. Slowly add the remaining 15% to 30% of water and continue stirring until a homogeneous mixture with good flowability and cohesiveness and no water separation is obtained.

[0062] S5. Molding and Curing: Pour the mixture into the mold, vibrate to compact it, cover with a film to prevent moisture evaporation, and cure at room temperature.

[0063] Example 1: Verification of Basic Formula and Room Temperature Curing

[0064] Weigh the following per cubic meter: 700 kg of Alite-Belit-Calcium Sulfoaluminate Cement (ABY Cement), 120 kg of Grade I fly ash (accounting for 12% of the total cementitious material, total cementitious material = ABY + fly ash + silica fume + silica powder = 700 + 120 + 130 + 40 = 990 kg), 130 kg of silica fume, 40 kg of silica powder, 1100 kg of quartz sand (particle size 0.15~0.6mm), 180 kg of steel fiber, 29.7 kg of polycarboxylate-based high-efficiency water-reducing agent (solid content 50%) (accounting for 3.0% of the total cementitious material), and 198 kg of water (water-cement ratio 0.2).

[0065] During preparation, ABY cement, fly ash, silica fume, silica powder, and quartz sand were first dry-mixed for 2.5 minutes until homogeneous. 80% (158.4 kg) of the total water was mixed with the water-reducing agent to form a solution, which was then slowly added to the dry materials and stirred for 4 minutes to form a slurry. Steel fibers were then evenly sprinkled in and stirred for 2.5 minutes. The remaining 20% ​​(39.6 kg) of water was added and stirred for 1.5 minutes, for a total stirring time of 10 minutes. The mixture achieved a slump spread of 680 mm without segregation. The mixture was poured into a 100 mm cubic meter mold, vibrated to compact, covered with plastic film, and cured in a standard curing room (20 ± 2℃, RH ≥ 95%).

[0066] The measured compressive strength was 82.11 MPa at 3 days and 148.23 MPa at 28 days; the flexural strength was 12.94 MPa at 3 days and 19.43 MPa at 28 days; the autogenous shrinkage was -305 με at 3 days and 205 με at 28 days (according to GB / T 50082); no heating measures were used during the entire curing process.

[0067] Example 2: Compatibility verification of high admixture synergy and water-reducing agent

[0068] Weigh out the following per cubic meter: 530 kg ABY cement, 200 kg granulated blast furnace slag (26.7% of total cementitious volume, total cementitious volume = 530 + 200 + 130 + 40 = 900 kg), 130 kg silica fume, 40 kg silica powder, 1250 kg quartz sand, 150 kg steel fiber, 31.5 kg of the same type of polycarboxylate superplasticizer (3.5% of total cementitious volume), and 162 kg water (water-cement ratio 0.18). The preparation process is the same as in Example 1, with a total mixing time of 12 minutes. The spread of the mixture is 650 mm. Under normal temperature curing, the 3-day compressive strength was 75.68 MPa, and the 28-day compressive strength was 142.16 MPa; the 3-day flexural strength was 11.55 MPa, and the 28-day flexural strength was 18.12 MPa. The slag activity was effectively activated, resulting in significant strength growth in the later stages. The 3-day autogenous shrinkage was -230 με, and the 28-day drying shrinkage was 310 με, with the shrinkage rate still significantly lower than that of traditional OPC-UHPC (typically >500 με). The setting time was controllable using a conventional commercially available polycarboxylate superplasticizer (initial setting 120 min, final setting 190 min), verifying the good match between ABY's rapid setting and the superplasticizer's retarding effect.

[0069] Example 3

[0070] 700 kg of Alite-Belit-Calcium Sulfoaluminate Cement (ABY Cement), 120 kg of Grade I fly ash, 10 kg of activated alumina powder (1% of the total cementitious material; total cementitious material = ABY + fly ash + silica fume + silica powder = 700 + 120 + 10 + 130 + 40 = 1000 kg), 130 kg of silica fume, 40 kg of silica powder, 1100 kg of quartz sand (particle size 0.15~0.6mm), 180 kg of steel fiber, 30 kg of the same type of polycarboxylate superplasticizer (3.0% of the total cementitious material), and 200 kg of water (water-cement ratio 0.2).

[0071] During preparation, ABY cement, activated alumina powder, silica fume, silica powder, and quartz sand were first dry-mixed for 2.5 minutes until homogeneous. 80% (160 kg) of the total water was mixed with the water-reducing agent to form a solution, which was then slowly added to the dry materials and stirred for 4 minutes to form a slurry. Steel fibers were then evenly sprinkled in and stirred for 2.5 minutes. The remaining 20% ​​(40 kg) of water was added and stirred for 1.5 minutes, for a total stirring time of 10 minutes. The mixture achieved a slump expansion of 680 mm without segregation. The mixture was poured into a 100 mm cubic mold, vibrated to compact, covered with plastic film, and cured in a standard curing room (20 ± 2℃, RH ≥ 95%).

[0072] Comparative example: Traditional OPC-based UHPC (high-temperature curing dependent)

[0073] Weigh out the following per cubic meter: 850 kg of P·I·42.5 silicate cement, 130 kg of silica fume, 40 kg of silica powder, 1122 kg of quartz sand, 180 kg of steel fiber, 28 kg of the same type of polycarboxylate superplasticizer (accounting for 2.8% of the total cementitious volume), and 170 kg of water (water-cement ratio 0.17). The preparation process is similar, but a retarding component (0.3% sodium gluconate) needs to be added to the mixture to prolong the setting time. After molding, the specimens were divided into two groups: Group A was cured under standard conditions (20℃), and Group B was steam cured at 90℃ for 48 hours. Results: Group A had a 3-day compressive strength of only 46.14 MPa and a 28-day compressive strength of 112.31 MPa; a 3-day flexural strength of 12.68 MPa and a 28-day flexural strength of 18.52 MPa; a 3-day autogenous shrinkage of up to 480 με and a 28-day drying shrinkage of 580 με. Group B, after heat curing, achieved a compressive strength of 115.23 MPa at 3 days and 145.43 MPa at 28 days; its flexural strength was 10.55 μm at 3 days and 17.98 μm at 28 days. However, its shrinkage remained high (350 με auto-shrinkage at 3 days and 500 με drying shrinkage at 28 days). This demonstrates that the traditional system, without heat curing, suffers from insufficient early strength and severe shrinkage.

[0074] Figure 2 This is a comparison of the autogenous shrinkage over time of ultra-high performance concrete (UHPC) prepared in Examples 1-2 and the comparative examples of the present invention under standard curing conditions (20±2℃). Figure 3 This is a comparison of the drying shrinkage of ultra-high performance concrete (UHPC) prepared in Examples 1-3 of this invention and the comparative examples under standard curing conditions (20±2℃) over time. It can be seen that, regardless of autogenous shrinkage or drying shrinkage, the examples all exhibit a slight expansion followed by slight shrinkage, demonstrating good volume stability compared to the significant shrinkage observed in the comparative examples.

[0075] Figure 4 This is a comparison of the compressive strength of Embodiments 1, 2, and 3 of the present invention and the comparative examples (Group A standard curing and Group B steam curing) after 3 days and 28 days. Figure 5 This is a comparison of the flexural strength at 3 days and 28 days for Examples 1, 2, and 3 of the present invention, and the comparative examples (Group A, standard curing; Group B, steam curing). It can be seen that the examples only require standard curing conditions to achieve the compressive strength of P·I·42.5 under steam curing conditions.

[0076] Combination Figure 6The main synergistic effect of the main components in the ABY cement-based UHPC of this invention is mainly reflected in the fact that the active mineral admixtures, silica fume, silica powder and ABY cement together constitute the cementitious material, which jointly promotes the strength growth of UHPC. The steel fiber and quartz sand together form the skeleton of UHPC. The use of water-reducing agent enables the low water-cement ratio. The active alumina micro powder and the calcium sulfoaluminate component in ABY cement work together to resist the shrinkage problem of UHPC.

[0077] The above comparison demonstrates that the production of UHPC using Alite-Belit-Calcium Sulfoaluminate cement improves the volume shrinkage problem of UHPC, reduces the temperature of cement production, lowers carbon emissions, solves the problems of difficult utilization and high recycling costs of bulk solid waste, and promotes the development of the cement industry towards a low-carbon direction.

[0078] This invention provides a concept and method for ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement and its preparation. Many methods and approaches exist for implementing this technical solution; the above description is merely a preferred embodiment of the invention. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of this invention, and these improvements and modifications should also be considered within the scope of protection of this invention. All components not explicitly stated in this embodiment can be implemented using existing technologies.

Claims

1. A type of ultra-high performance concrete based on Alite-Belit-Calcium Sulfoaluminate cement, characterized in that, Per cubic meter, it contains the following components in parts by weight: 550-800 parts of Alite-Belit-Calcium Sulfoaluminate Cement; 100-300 parts of active mineral admixture; 100-200 parts silica fume; 30-70 parts of silica powder; All four of these can be used together as cementing materials; 900-1300 parts of quartz sand; 120-250 parts steel fiber; 15-35 parts of water-reducing agent; 130-180 parts water; And optional component: 0-30 parts of activated alumina micro powder.

2. The ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement according to claim 1, characterized in that, The mineral phase composition of the aforementioned Alite-Belit-Calcium Sulfoaluminate cement, by mass percentage, includes C3S: 30~50%, C2S: 30~50%, C4A3S: 10~20%, C4AF: 0~5%, and CaSO4: 0~5%.

3. The ultra-high performance concrete based on Alite-Belit-Calcium Sulfoaluminate cement according to claim 1, characterized in that, The active mineral admixture is one or a combination of two of fly ash and granulated blast furnace slag; its dosage is 10% to 35% of the total mass of cementitious materials.

4. The ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement according to claim 1, characterized in that, The maximum particle size of the quartz sand is no greater than 0.6 mm.

5. The ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement according to claim 1, characterized in that, The aspect ratio of the steel fiber is 10~15 / 0.

2.

6. The ultra-high performance concrete based on alite-belite-calcium sulfoaluminate cement according to claim 1, characterized in that, The water-reducing agent is a polycarboxylate-based high-efficiency water-reducing agent, and its dosage is 1.5% to 3.0% of the total mass of the cementitious material.

7. The ultra-high performance concrete based on Alite-Belit-Calcium Sulfoaluminate cement according to claim 1, characterized in that, The water-cement ratio used for mixing concrete is 0.14 to 0.

20.

8. The method for preparing ultra-high performance concrete according to claim 1, characterized in that, Includes the following steps: S1. Dry material premixing: Add Alite-Belit-Calcium Sulfoaluminate cement, active mineral admixtures, silica fume, silica powder, quartz sand and optional active alumina micro powder into a mixer and dry mix until the materials are uniform. S2. Mix 70% to 85% of the total water volume with the water-reducing agent to form a solution; while the mixer is running, slowly and evenly add the solution to the dry material in step S1, and continue stirring to form a slurry; S3. Keep the mixer running and evenly and disperse the steel fibers into the slurry obtained in step S2. Continue to stir to make the steel fibers evenly distributed. S4. Slowly add the remaining 15% to 30% of water and continue stirring until a homogeneous mixture with good flowability and cohesiveness and no water separation is obtained. S5. Molding and Curing: Pour the mixture into the mold, vibrate to compact it, cover with a film to prevent moisture evaporation, and cure.

9. The method for preparing ultra-high performance concrete according to claim 8, characterized in that, The total mixing time in steps S1 to S4 should be controlled between 8 and 15 minutes.

10. The method for preparing ultra-high performance concrete according to claim 8, characterized in that, In step S5, the curing temperature shall not exceed 30°C.

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