An anti-disturbance slightly expanding lightweight ultra-high performance concrete and its preparation method

Abstract

The present invention provides a disturbance-resistant slightly expanded lightweight ultra-high performance concrete and a preparation method thereof. For the concrete of the present invention, the fiber bridging effect of whiskers and temperature shrinkage indented fibers and the micro pre-compressive stress of temperature shrinkage indented fibers under the excitation of hydration heat release can effectively inhibit the generation of microcracks under disturbance; the microcrack healing effect of nanocellulose and the internal curing effect of saturated pre-wetted coal gangue ceramsite synergistically repair the microstructural damage generated under strong disturbance, further improving the disturbance resistance of the concrete. The internal curing effect of saturated pre-wetted coal gangue ceramsite and the compensating shrinkage of the expansive agent synergistically improve the volume stability of the concrete. The 28-day compressive strength of the concrete of the present invention is > 120 MPa, the 56-day expansion rate is ≤ 100 με, the bulk density is reduced by more than 20% compared with that of ordinary ultra-high performance concrete, and the disturbance-resistant strength retention rate is ≥ 95%. It shows excellent bonding and durability performance, and the comprehensive performance is greatly improved, having important practical application value.

Description

Technical Field

[0001] The present invention relates to the technical field of building materials, and particularly to a disturbance-resistant slightly-expansive lightweight ultra-high performance concrete and a preparation method thereof. Background Art

[0002] With the increasing complexity of the national transportation network and the acceleration of the urbanization process, bridges, as key nodes of transportation infrastructure, are under unprecedented pressure. Many bridges need to be repaired, strengthened and widened due to reasons such as long-term disrepair and overloaded traffic loads. Bridges are usually important transportation hubs. Once the use is interrupted, it may have a huge impact on urban traffic and even regional economy. Therefore, when repairing, strengthening and widening bridges, usually without interrupting traffic, ensuring the continuity of traffic flow and the stability of service level is the primary goal of engineering construction. The construction method without interrupting traffic puts forward higher requirements for the performance of fresh concrete: (1) Since the steel bar arrangement is relatively dense in the reinforcement or widening project, the construction requires the slurry to have excellent flow state, but it is currently a key difficulty to balance good workability and high disturbance resistance; (2) Old bridges usually approach or operate overloaded due to years of service or insufficient design load. Traditional concrete or ultra-high performance concrete is difficult to meet the requirements of repair, strengthening and widening projects due to its large size and self-weight; (3) Due to the difference in volume stability between old and new concrete (the shrinkage of old concrete has tended to be stable, while the newly poured concrete is still in the development process), the shrinkage of newly poured concrete may cause the deterioration of the bonding interface between old and new concrete, so higher requirements are also put forward for the volume stability of concrete. However, the current research on disturbance-resistant concrete mainly focuses on aspects such as the selection of cementitious materials for ordinary concrete or rapid-hardening concrete, the regulation of admixtures and construction technology, and mainly focuses on improving the disturbance resistance by enhancing the rapid hardening and early strength of concrete. However, in large-scale repair, strengthening and widening projects, a longer workable operation time and good disturbance resistance are required. Currently, there is no research on disturbance-resistant lightweight ultra-high performance concrete. Therefore, there is an urgent need to develop a disturbance-resistant slightly-expansive lightweight ultra-high performance concrete to provide a more efficient, reliable and durable solution for the maintenance, renovation and upgrade of old bridges. Summary of the Invention

[0003] In view of this, the present invention provides a disturbance-resistant slightly-expansive lightweight ultra-high performance concrete and a preparation method thereof to solve or partially solve the problems existing in the prior art.

[0004] In a first aspect, the present invention provides a disturbance-resistant slightly expanded lightweight ultra-high performance concrete, comprising the following raw materials in parts by weight: 35-40 parts of cement, 5-7 parts of fly ash microspheres, 6-9 parts of silica fume, 0.9-1.5 parts of whiskers, 0.05-0.10 parts of nano-cellulose, 18-25 parts of spherical coal gangue ceramsite, 5-10 parts of crushed coal gangue ceramsite, 2.2-3.3 parts of expansion agent, 0.04-0.09 parts of temperature shrinkage grooved fiber, 6.0-6.8 parts of steel fiber, 1.1-1.5 parts of water reducing agent, and 7.0-9.2 parts of water.

[0005] Preferably, the loss on ignition of the fly ash microspheres is ≤3.0%, the water demand ratio is ≤90%, and the spherical particle volume ratio is ≥95%.

[0006] Preferably, the SiO2 mass content of the silica fume is ≥95%, the specific surface area is ≥19500m 2 / kg, and the 28d activity index is ≥100%.

[0007] Preferably, the spherical coal gangue ceramsite and the crushed coal gangue ceramsite have a continuous gradation of 0.075-4.75mm; the fineness modulus of the spherical coal gangue ceramsite and the crushed coal gangue ceramsite is 3.1-3.7, the cylinder compressive strength is ≥12.0MPa, the bulk density is 700-900kg / m 3 3, and the apparent density is 1500-1700kg / m 3 3, and the saturated surface dry water absorption rate is 12.0%-14.0%.

[0008] Preferably, the whiskers are one of silicon carbide whiskers, calcium sulfate whiskers and calcium carbonate whiskers;

[0009] The whiskers have a diameter of 0.1-2μm, a length of 10-30μm, and a specific surface area of 20-80m 2 / kg.

[0010] Preferably, the nano-cellulose is cellulose nanofiber;

[0011] The cellulose nanofiber has a length of 1-10μm, a diameter of 10-60nm, and a specific surface area of 100-130m 2 / kg.

[0012] Preferably, the water reducing agent is a polycarboxylate-based superplasticizer.

[0013] Preferably, the expansion agent is a high-performance expansion agent suitable for low water-binder ratio concrete, with a specific surface area of ≥250m 2 / kg and a 7-day restricted expansion rate of ≥0.035%.

[0014] Preferably, the shrinkage rate of the temperature-shrinkage grooved fiber is 0.5-12%, the response temperature is 30-100°C, the tensile strength is 500-1500 MPa, and the elastic modulus is 7-30 GPa.

[0015] In a second aspect, the present invention also provides a method for preparing the anti-disturbance slightly expanded lightweight ultra-high performance concrete as described above, which is characterized by comprising the following steps:

[0016] S1. Mix 18-25 parts by weight of spherical coal gangue ceramsite and 5-10 parts by weight of crushed coal gangue ceramsite to obtain coal gangue ceramsite; add water to the coal gangue ceramsite, and stir evenly to fully pre-wet the coal gangue ceramsite. Cover and place it in a cool and dry place for standing to obtain saturated pre-wetted coal gangue ceramsite; wherein, the mass of water is 12-14% of the mass of the coal gangue ceramsite;

[0017] S2. Pour 35-40 parts by weight of cement, 6-9 parts by weight of silica fume, 5-7 parts by weight of fly ash microspheres, 2.2-3.3 parts by weight of an expansive agent, and 0.9-1.5 parts by weight of whiskers into a mixer for mixing to obtain a premix;

[0018] S3. Pour the saturated pre-wetted coal gangue ceramsite in S1 into the premix and stir to obtain a mixture;

[0019] S4. Add 0.05-0.10 parts by weight of nanocellulose and 1.1-1.5 parts by weight of a water reducer to 7.0-9.2 parts by weight of water. After stirring evenly, pour it into the mixture in S3 and stir to obtain a mixed slurry;

[0020] S5. Uniformly add 6.0-6.8 parts by weight of steel fiber and 0.04-0.09 parts by weight of temperature-shrinkage grooved fiber to the mixed slurry in S4. After stirring, mold it, cover it with a film for curing and then demold it, and then carry out standard curing or steam curing to obtain the anti-disturbance slightly expanded lightweight ultra-high performance concrete.

[0021] The anti-disturbance slightly expanded lightweight ultra-high performance concrete and its preparation method of the present invention have the following beneficial effects compared with the prior art:

[0022] 1. The anti-disturbance slightly expansive lightweight ultra-high performance concrete prepared by the present invention has the characteristics of light self-weight, high anti-disturbance performance, and excellent volume stability. It effectively solves the problems of heavy self-weight of concrete and the difficulty in coexisting high anti-disturbance and high fluidity performance in the current repair, reinforcement, and widening projects of old bridges without traffic interruption. At the same time, it has a reasonable operable construction time and excellent comprehensive performance, which is of great significance to the repair, reinforcement, and widening projects of large-scale structures without traffic interruption. The two types of coal gangue lightweight aggregates with different particle shapes can not only optimize and adjust the viscosity of the concrete paste and reduce the self-weight, but also be calcined from solid waste coal gangue using biomass fuel, with high mechanical properties and excellent water storage and release effects, which helps the resource utilization of coal gangue and can provide excellent internal curing effects, effectively reducing the autogenous shrinkage of ultra-high performance concrete and improving the performance of the interfacial transition zone between lightweight aggregates and the matrix. At the same time, in the preparation process of the present invention, saturated pre-wetted coal gangue ceramsite is used, and the internal curing of saturated pre-wetted coal gangue ceramsite and the shrinkage compensation of the expansive agent synergistically improve the volume stability of ultra-high performance concrete. Therefore, the anti-disturbance slightly expansive lightweight ultra-high performance concrete prepared by the present invention has good resistance to the vibration generated by old bridges in the repair, reinforcement, and widening projects without traffic interruption.

[0023] 2. For the anti-disturbance slightly expansive lightweight ultra-high performance concrete of the present invention, the addition of whiskers, temperature shrinkage grooved fibers, and nanocellulose can improve the anti-disturbance performance of the concrete during the driving load disturbance process and after being strongly disturbed, respectively. Among them, the fiber bridging effect of whiskers and temperature shrinkage grooved fibers can effectively inhibit the generation of microcracks in the concrete under the disturbance during the setting and hardening period, and the temperature shrinkage grooved fibers can shrink under the excitation of heat of hydration, generating micro-precompressive stress on the surrounding concrete matrix, which can further resist the disturbance effect. At the same time, the microcrack healing effect of nanocellulose and the internal curing effect of saturated pre-wetted coal gangue lightweight aggregates can synergistically repair the microstructural damage generated under strong disturbance, thereby enhancing the anti-disturbance performance of the concrete. In addition, the temperature shrinkage grooved fibers and steel fibers can synergistically enhance the toughness of the concrete, thereby improving the anti-fatigue performance of the concrete pavement during service, which is of great significance for improving the service life of concrete bridge structures. The bulk density of the anti-disturbance slightly expansive lightweight ultra-high performance concrete obtained by the present invention < 2050 kg / m 3 , and at the same time, the 28-day compressive strength > 120 MPa, the 56-day expansion rate ≤ 100 με. Compared with the current ultra-high performance concrete, the bulk density is reduced by about 20% or more, the anti-disturbance strength retention rate ≥ 95%, and it shows excellent bonding performance and durability. The comprehensive performance has been greatly improved, which has important practical application value for the repair, reinforcement, and widening projects without traffic interruption. Detailed implementation mode

[0024] Next, in combination with the embodiments of the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0025] It should be noted that the description order of the following embodiments does not limit the preferred order of the embodiments. Additionally, in the description of this application, the term "including" means "including but not limited to". The various embodiments of the present invention may exist in a range form; it should be understood that the description in a range form is only for convenience and brevity, and should not be construed as a rigid limitation on the scope of the present invention; therefore, it should be considered that the described range description has specifically disclosed all possible sub-ranges and individual values within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and individual numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Additionally, whenever a numerical range is indicated herein, it means including any cited number (fraction or integer) within the indicated range.

[0026] The embodiments of this application provide a kind of anti-disturbance micro-expansion lightweight ultra-high performance concrete, which comprises the following raw materials in parts by weight: 35 - 40 parts of cement, 5 - 7 parts of fly ash microspheres, 6 - 9 parts of silica fume, 0.9 - 1.5 parts of whiskers, 0.05 - 0.10 parts of nano-cellulose, 18 - 25 parts of spherical coal gangue ceramsite, 5 - 10 parts of crushed coal gangue ceramsite, 2.2 - 3.3 parts of expansion agent, 0.04 - 0.09 parts of temperature shrinkage grooved fiber, 6.0 - 6.8 parts of steel fiber, 1.1 - 1.5 parts of water reducing agent, and 7.0 - 9.2 parts of water.

[0027] The anti-disturbance micro-expansion lightweight ultra-high performance concrete of the present invention uses whiskers and nano-cellulose to prepare high anti-disturbance lightweight ultra-high performance concrete. On the one hand, by changing the gradation of coal gangue lightweight aggregate to adjust the slurry viscosity and adding nano-fiber particles such as whiskers and nano-cellulose externally to enhance the anti-disturbance performance of the lightweight ultra-high performance concrete; on the other hand, through the internal curing effect of saturated pre-wetted lightweight aggregate and the compensation shrinkage of the expansion agent to realize the regulation of the volume stability of the lightweight ultra-high performance concrete. At the same time, the addition of lightweight aggregate can not only reduce the self-weight of the ultra-high performance concrete, but also the internal curing effect of water release from the lightweight aggregate can enhance the anti-disturbance effect of the concrete, thereby realizing the high fluidity, anti-disturbance and micro-expansion of the lightweight ultra-high performance concrete.

[0028] In some embodiments, the cement is PO 52.5 cement, which is a commercially available material.

[0029] In some embodiments, the loss on ignition of fly ash microspheres is ≤ 3.0%, the water demand ratio is ≤ 90%, and the volume ratio of spherical particles is ≥ 95%.

[0030] In some embodiments, the mass content of SiO2 in silica fume is ≥ 95%, the specific surface area is ≥ 19500 m 2 / kg, and the 28-day activity index is ≥ 100%.

[0031] In some embodiments, the spherical coal gangue ceramsite and the crushed coal gangue ceramsite have a continuous gradation of 0.075 - 4.75 mm;

[0032] The fineness modulus of the spherical coal gangue ceramsite and the crushed coal gangue ceramsite is 3.1 - 3.7, the cylinder compressive strength is ≥ 12.0 MPa, the bulk density is 700 - 900 kg / m 3 , and the apparent density is 1500 - 1700 kg / m 3 , and the saturated surface dry water absorption rate is 12.0% - 14.0%.

[0033] Specifically, in the present invention, the crushed coal gangue ceramsite refers to any shape other than the spherical coal gangue ceramsite.

[0034] In some embodiments, the whisker is one of silicon carbide whiskers, calcium sulfate whiskers, and calcium carbonate whiskers; preferably, the whisker is silicon carbide whiskers;

[0035] The diameter of the whisker is 0.1 - 2 μm, the length is 10 - 30 μm, and the specific surface area is 20 - 80 m 2 / kg.

[0036] In some embodiments, the nanofibrillated cellulose is cellulose nanofibers;

[0037] The length of the cellulose nanofibers is 1 - 10 μm, the diameter is 10 - 60 nm, and the specific surface area is 100 - 130 m 2 / kg.

[0038] The nanocellulose used in this application has a high specific surface area and a high cellulose content. On the one hand, the hydrophilic nanocellulose can induce the growth of calcium silicate hydrate (C-S-H gel), form a bridge structure between the hydration products, optimize the pore size distribution and pore structure of the concrete, and improve the structural density. On the other hand, the fibers can form a network structure in the microcracks to prevent crack propagation. And under the internal curing condition of water release from lightweight aggregates, the fibers can further promote the hydration of unhydrated cement and fill the microcracks. The above properties are of great significance for the anti-disturbance performance of concrete. And the nanocellulose is derived from plant fibers (such as wood, agricultural waste, etc.), belongs to renewable resources, and has a wide source, reducing carbon emissions. At the same time, the silicon carbide whiskers used in this research have a large aspect ratio, a high specific surface area and a high modulus, which can effectively disperse the applied stress evenly to each area of the concrete, reduce the local damage caused by stress concentration, and have good interfacial bonding properties with hydration products such as C-S-H gel, further enhancing the anti-disturbance performance of lightweight ultra-high performance concrete. In addition, at the macroscopic scale, the temperature-shrinkage grooved fibers can shrink under the excitation of heat release during hydration, and then generate micro-precompressive stress on the surrounding concrete matrix, which can further resist the disturbance effect.

[0039] In some embodiments, the water reducing agent is a polycarboxylate-based superplasticizer with a solid content of ≥ 30%.

[0040] In some embodiments, the expansive agent is a high-performance expansive agent suitable for low water-binder ratio concrete with a specific surface area of ≥ 250 m 2 / kg and a 7-day restricted expansion rate of ≥ 0.035%.

[0041] In some embodiments, the shrinkage rate of the temperature-shrinkage grooved fibers is 0.5 - 12%, the response temperature is 30 - 100 °C, the tensile strength is 500 - 1500 MPa, and the elastic modulus is 7 - 30 GPa.

[0042] Specifically, the specific preparation method of the temperature-shrinkage grooved fibers of the present invention includes the following steps:

[0043] 1) Use two extruders to extrude the heat-shrinkable core material mixture and the heat-shrinkable skin material mixture into a die head with two cavities respectively. Among them, the heat-shrinkable skin material enters the corresponding skin cavity, and the heat-shrinkable core material enters the corresponding core cavity. The materials in the two cavities converge at the position of the spinneret of the extruder. Among them, the spinneret has an inner ring and an outer ring. The inner ring of the spinneret is connected to the core cavity, and the outer ring of the spinneret is connected to the skin cavity. The two molten materials are extruded (melt extrusion) through the spinneret and stick together in the air, cooled by a cold water tank, and then drawn in hot water at 90 - 100 °C to form a composite fiber with a skin-core structure;

[0044] Among them, in the heat-shrinkable skin material mixture, each raw material and its mass percentage are as follows: polyoxymethylene 97.5%, maleic anhydride grafted compatibilizer (provided by Dongguan Shenghao Plastic Raw Materials Co., Ltd., model PP-G-MAH) 1.5%, and phthalate (plasticizer) 1%; the extrusion pressure of the skin material cavity is 8 MPa, and the melting temperature is maintained at 250 °C;

[0045] In the heat-shrinkable core material mixture, each raw material and its mass percentage are as follows: polyester 98%, steel-increasing nucleating agent 2% (composed of dibenzylidene sorbitol and sodium benzoate in a mass ratio of 1:1); the extrusion pressure is 6 MPa, and the melting temperature is maintained at 210 °C;

[0046] After the skin material and the core material converge, they are extruded through a spinneret. The extrusion temperature of the two molten materials is 220 °C, and the extrusion pressure is 7 MPa;

[0047] The average diameter of the obtained core material fibers is 0.15 mm, and the thickness of the skin layer fibers is 0.05 - 0.1 mm;

[0048] 2) Add the obtained composite fibers into an octamethylcyclotetrasiloxane silicone solution for modification (the time is 12 h), and make surface indentations after drying to increase the bonding performance with the concrete paste;

[0049] 3) Add the obtained composite fibers into a modified polyvinyl alcohol solution containing an expansion component for coating modification (the time is 24 h), take them out and dry them to prepare temperature-shrinkage indented fibers;

[0050] Among them, the modified polyvinyl alcohol solution used is obtained by uniformly mixing a polyvinyl alcohol solution (5 wt%) and a liquid expansion agent in a mass ratio of 7:3 (1:0.43).

[0051] After the water-soluble film on the surface of the temperature-shrinkage indented fibers obtained by the present invention dissolves, the expansion component, etc. can react with the concrete to cause an expansion reaction. The free expansion rate of the expansion agent in a closed environment is 0.02%; the bonding strength between the skin-core fibers and the concrete is greater than 20 MPa; the shrinkage rate of the obtained composite fibers is 0.5 - 12%, the response temperature is 30 - 100 °C, the tensile strength is 700 MPa, and the elastic modulus is 15.0 GPa.

[0052] In some embodiments, the water is ordinary tap water, meeting the requirements of the "Standard for Water Used in Concrete" JGJ63.

[0053] The anti-disturbance slightly expanding lightweight ultra-high performance concrete of the present invention adjusts the paste viscosity by reasonably optimizing the proportion of cementitious materials and the particle shape and gradation of high-performance coal gangue ceramsite; enhances the anti-disturbance performance of the lightweight ultra-high performance concrete through whiskers, temperature shrinkage indented fibers and nanocellulose; synergistically improves the toughness of the concrete and enhances the mechanical properties through temperature shrinkage indented fibers and steel fibers. At the same time, the internal curing effect provided by saturated pre-wetted coal gangue lightweight aggregate and the shrinkage compensation of the expansive agent synergistically improve the volume stability of the concrete. In addition, the coal gangue ceramsite used in the present invention is calcined from solid waste coal gangue through biomass fuel, which is of great significance for the sustainable development of the environment. The bulk density of the anti-disturbance slightly expanding lightweight ultra-high performance concrete obtained by the present invention is ≤2050 kg / m 3 , the fluidity is 530 mm - 670 mm, and at the same time the 28-day compressive strength is ≥120 MPa, the 56-day expansion rate is ≤100 με, and the anti-disturbance strength retention rate is ≥95%. Compared with the bulk density of the current ultra-high performance concrete (about 2600 kg / m 3 ), it is reduced by more than about 20%, effectively reducing the load of the original structure. At the same time, it has excellent volume stability and bonding properties, and the comprehensive performance is greatly improved, which has important practical application value for the repair and reinforcement without interrupting traffic and the widening project.

[0054] Based on the same inventive concept, the present invention also provides a preparation method of the above-mentioned anti-disturbance slightly expanding lightweight ultra-high performance concrete, which includes the following steps:

[0055] S1. Mix 18 - 25 parts by weight of spherical coal gangue ceramsite and 5 - 10 parts by weight of crushed coal gangue ceramsite to obtain coal gangue ceramsite; add water to the coal gangue ceramsite and stir evenly to fully pre-wet the coal gangue ceramsite, cover and place it in a cool and dry place for static placement to obtain saturated pre-wetted coal gangue ceramsite; wherein, the mass of water is 12 - 14% of the mass of the coal gangue ceramsite;

[0056] S2. Pour 35 - 40 parts by weight of cement, 6 - 9 parts by weight of silica fume, 5 - 7 parts by weight of fly ash microspheres, 2.2 - 3.3 parts by weight of expansive agent, and 0.9 - 1.5 parts by weight of whiskers into a mixer and mix to obtain a premix;

[0057] S3. Pour the saturated pre-wetted coal gangue ceramsite in S1 into the premix and stir to obtain a mixture;

[0058] S4. Add 0.05 - 0.10 parts by weight of nanocellulose and 1.1 - 1.5 parts by weight of water reducer to 7.0 - 9.2 parts by weight of water, stir evenly and then pour it into the mixture in S3 and stir to obtain a mixed paste;

[0059] S5. 6.0 to 6.8 parts by weight of steel fiber and 0.04 to 0.09 parts by weight of temperature shrinkage notched fiber are uniformly added to the mixed slurry in S4, and molded after stirring. After covering with a film and curing, the mold is removed, and then standard curing or steam curing is performed to obtain the disturbance-resistant micro-expansion lightweight ultra-high performance concrete.

[0060] In some embodiments, 18 to 25 parts by weight of spherical gangue ceramsite and 5 to 10 parts by weight of crushed stone-shaped gangue ceramsite are mixed in a suitable container to obtain gangue ceramsite; water is added to the gangue ceramsite, stirred several times to ensure the uniformity of aggregate pre-wetting, covered and placed in a cool and dry place to stand, to obtain saturated pre-wetted gangue ceramsite; wherein the mass of water is 12 to 14% of the mass of the gangue ceramsite (i.e., the water content is sufficient for saturated pre-wetting).

[0061] In some embodiments, 35 to 40 parts by weight of cement, 6 to 9 parts of silica fume, 5 to 7 parts of fly ash microspheres, 2.2 to 3.3 parts of expansion agent, and 0.9 to 1.5 parts of whisker are poured into a mixer and mixed at a speed of 35±2 r / min for 3 minutes to obtain a premix.

[0062] In some embodiments, the saturated pre-wetted coal gangue ceramsite in S1 is poured into the premix, and stirred at a rotation speed of 35±2 r / min for 3 minutes to obtain a mixture.

[0063] In some embodiments, 0.05 to 0.10 parts by weight of nanocellulose and 1.1 to 1.5 parts of a water reducer are added to 7.0 to 9.2 parts of water, stirred evenly, and then poured into the mixture of S3, and stirred at a speed of 35 ± 2 r / min for 5 minutes to obtain a mixed slurry;

[0064] In some embodiments, 6.0 to 6.8 parts by weight of steel fiber and 0.04 to 0.09 parts by weight of temperature shrinkage notched fiber are uniformly added to the mixed slurry in S4, fully stirred at a speed of 35±2r / min for 4 minutes, loaded into a mold after stirring evenly, covered with a film and cured for 24 hours before demolding, and then standard curing or steam curing is carried out to obtain the anti-disturbance micro-expansion lightweight ultra-high performance concrete.

[0065] The anti-disturbance slightly expanded lightweight ultra-high performance concrete prepared in this application has the characteristics of light weight, high anti-disturbance performance, and excellent volume stability. It effectively solves the problems of high self-weight of current concrete and the difficulty in coexisting high anti-disturbance performance and high fluidity. At the same time, it has excellent comprehensive performance, which is of great significance for repair, reinforcement, and widening projects without interrupting traffic. The raw material coal gangue lightweight aggregate used is calcined by biomass fuel, effectively reducing CO2 emissions during the production process, consuming a large amount of solid waste coal gangue, and reducing the consumption of natural sand and gravel. This application uses whiskers and nanocellulose, which not only enhance its anti-disturbance performance through dense filling and fiber bridging during the disturbance process, but also the temperature shrinkage indentation fibers can shrink under the excitation of hydration heat release, thereby generating micro-precompressive stress on the surrounding concrete matrix, which can further resist the disturbance effect. In addition, if it is severely disturbed and damaged in the early stage, the present invention can also repair the damage of the micro-structure through the micro-crack healing effect of nanocellulose and the internal curing effect of lightweight aggregate, further improving its anti-disturbance performance, which has an important guiding role for the research and preparation of anti-disturbance lightweight ultra-high performance concrete. The bulk density of the anti-disturbance slightly expanded lightweight ultra-high performance concrete obtained in the present invention is ≤2050 kg / m 3 , the fluidity is 530 mm - 670 mm, and at the same time, the 28-day compressive strength is ≥120 MPa, the 56-day expansion rate is ≤100 με, the anti-disturbance strength retention rate is ≥0.95. Compared with the bulk density of current ordinary ultra-high performance concrete (about 2600 kg / m 3 ), it is reduced by about 20% or more, the anti-disturbance performance is greatly improved, and at the same time, it has excellent bonding performance and durability, and the comprehensive performance is greatly improved, having important practical application value.

[0066] The following further illustrates the anti-disturbance slightly expanded lightweight ultra-high performance concrete and its preparation method of the present invention with specific examples. This part further illustrates the content of the present invention in combination with specific examples, but should not be construed as a limitation to the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well-known to those skilled in the art. Unless otherwise specified, the reagents, methods, and equipment used in the present invention are conventional reagents, methods, and equipment in the art.

[0067] The following tests simulate three different traffic conditions: light traffic load (amplitude 1 mm, frequency 3 Hz), medium traffic load (amplitude 2.5 mm, frequency 5 Hz), and heavy traffic load (amplitude 4 mm, frequency 8 Hz). Starting from the time of pouring, the disturbance is continuously carried out until the final setting time corresponding to each example and comparative example is reached, and the working performance (setting time and fluidity) and mechanical properties (compressive, flexural, splitting tensile, bonding, etc. properties) of the specimens are respectively tested.

[0068] In the following examples and comparative examples, the cement is PO·52.5 cement provided by Huaxin Cement Co., Ltd., with a specific surface area of 365 m 2 / kg; the fly ash microspheres are provided by Tianjin Zhucheng New Materials Co., Ltd., with a loss on ignition of 2.5%, a specific surface area of 1300 m 2 / kg, and an activity index at 28 days ≥ 90%; the silica fume is provided by Shanghai Tokon Building Materials Co., Ltd., with a specific surface area of 21500 m 2 / kg; the silicon carbide whiskers are provided by Formans Technology Co., Ltd., with a diameter of 0.5 - 2 μm, a length of 10 - 20 μm, and an elastic modulus of 450 - 700 GPa; the nanofibrillated cellulose is provided by Jinan Shengquan Group Co., Ltd., specifically Shengquan Group nanofibrillated cellulose, with a diameter of 10 - 60 nm and a length of 1 - 5 μm; the spherical coal gangue ceramsite and the crushed coal gangue ceramsite are provided by Huainan Dongchen Group Co., Ltd., both with a continuous gradation of 0.075 - 4.75 mm, a fineness modulus of 3.1 - 3.7, a cylinder compressive strength ≥ 12 MPa, and a bulk density of 700 - 800 kg / m 3 ; the expansive agent is provided by Wuhan Sanyuan Special Building Materials Co., Ltd., specifically HPS high-performance expansive clinker, with a specific surface area ≥ 250 m 2 / kg and a 7-day restricted expansion rate ≥ 0.035%; the water-reducing agent is a coagulation-promoting polycarboxylate-based superplasticizer produced by Jiangsu Sobute New Materials Co., Ltd., with a solid content of 30%; the water is ordinary tap water.

[0069] In the following examples, the preparation method of the thermal shrinkage indentation fiber includes the following steps:

[0070] 1) Using two extruders, the heat shrinkage core material mixture and the heat shrinkage skin material mixture are respectively extruded into a die head with two cavities. Among them, the heat shrinkage skin material enters the corresponding skin cavity, and the heat shrinkage core material enters the corresponding core cavity. The materials in the two cavities converge at the position of the spinneret of the extruder. The spinneret has an inner ring and an outer ring. The inner ring of the spinneret is connected to the core cavity, and the outer ring of the spinneret is connected to the skin cavity. The two molten materials are extruded through the spinneret (molten extrusion) and adhered together in the air, cooled by a cold water tank, and then drawn in hot water at 90 - 100 °C to form a composite fiber with a skin-core structure;

[0071] Among them, in the heat shrinkage skin material mixture, the raw materials and their mass percentages are as follows: 97.5% polyoxymethylene, 1.5% maleic anhydride grafted compatibilizer (provided by Dongguan Shenghao Plastic Raw Materials Co., Ltd., model PP-G-MAH), and 1% phthalate (plasticizer); the extrusion pressure of the skin cavity is 8 MPa, and the melting temperature is maintained at 250 °C;

[0072] In the heat-shrinkable core material mixture, each raw material and its mass percentage are as follows: polyester 98%, steel nucleating agent 2% (composed of dibenzylidene sorbitol and sodium benzoate in a mass ratio of 1:1); the extrusion pressure is 6 MPa, and the melting temperature is maintained at 210 °C;

[0073] After the skin material and the core material converge, they are extruded through a spinneret. The extrusion temperature of the two molten materials is 220 °C, and the extrusion pressure is 7 MPa;

[0074] The average diameter of the obtained core material fibers is 0.15 mm, and the thickness of the skin layer fibers is 0.05 - 0.1 mm;

[0075] 2) Add the obtained composite fibers to an octamethylcyclotetrasiloxane silicone solution for modification (for 12 h), and after drying, make surface indentations to increase the bonding performance with the concrete paste;

[0076] 3) Add the obtained composite fibers to a modified polyvinyl alcohol solution containing an expansion component for coating modification (for 24 h), take them out and dry to prepare temperature-shrinkage indented fibers;

[0077] Among them, the modified polyvinyl alcohol solution used is obtained by uniformly mixing a polyvinyl alcohol solution (5 wt%) and a liquid expansion agent in a mass ratio of 7:3 (1:0.43).

[0078] Example 1

[0079] The embodiment of the present application provides a disturbance-resistant slightly expanded lightweight ultra-high performance concrete, which includes the following raw materials in parts by weight: 39 parts of cement, 6 parts of fly ash microspheres, 8.6 parts of silica fume, 1.5 parts of silicon carbide whiskers, 0.09 part of nanocellulose, 18 parts of spherical coal gangue ceramsite, 10 parts of crushed coal gangue ceramsite, 3.0 parts of expansion agent, 0.08 part of temperature-shrinkage indented fibers, 6.7 parts of steel fibers, 1.1 parts of polycarboxylate water reducer, and 7.3 parts of water.

[0080] The preparation method of the above disturbance-resistant slightly expanded lightweight ultra-high performance concrete includes the following steps:

[0081] S1. Mix 18 parts of spherical coal gangue ceramsite and 10 parts of crushed coal gangue ceramsite by weight to obtain coal gangue ceramsite; add water to the coal gangue ceramsite and stir to pre-wet the coal gangue ceramsite, cover it and place it in a cool and dry place to stand to obtain saturated pre-wetted coal gangue ceramsite; among them, the mass of water is 13% of the mass of the coal gangue ceramsite;

[0082] S2. Pour 39 parts of cement, 8.6 parts of silica fume, 6 parts of fly ash microspheres, 3.0 parts of expansion agent, and 1.5 parts of calcium carbonate whiskers by weight into a mixer and mix them at a rotation speed of 35 ± 2 r / min for 3 min to obtain a premix;

[0083] S3, pouring the saturated pre-wetted coal gangue ceramsite in S1 into the premix, stirring to obtain a mixture;

[0084] S4, adding 0.09 parts by weight of nanocellulose and 1.1 parts of polycarboxylate water-reducing agent to 7.3 parts of water, stirring evenly, pouring into the mixture of S3, stirring at a speed of 35±2r / min for 5min, to obtain a mixed slurry;

[0085] S5. 6.7 parts by weight of steel fiber and 0.08 parts by weight of temperature shrinkage notched fiber are uniformly added to the mixed slurry in S4, and fully stirred at a speed of 35±2r / min for 4 minutes. After stirring evenly, the mixture is loaded into a mold, covered with a film and cured for 24 hours, and then the mold is removed. Then, standard curing is carried out (at a temperature of 20°C and a relative humidity of 98%RH for 28 days) to obtain the anti-disturbance micro-expansion lightweight ultra-high performance concrete.

[0086] Example 2

[0087] The embodiment of the present application provides an anti-disturbance micro-expansion lightweight ultra-high performance concrete, comprising the following raw materials in parts by weight: 37 parts of cement, 7 parts of fly ash microspheres, 7.8 parts of silica fume, 1.3 parts of silicon carbide whiskers, 0.08 parts of nanocellulose, 22 parts of spherical coal gangue ceramsite, 7.2 parts of crushed coal gangue ceramsite, 2.6 parts of expansion agent, 0.06 parts of temperature shrinkage notched fiber, 6.5 parts of steel fiber, 1.2 parts of polycarboxylic acid water reducer, and 8.0 parts of water.

[0088] The method for preparing the above-mentioned anti-disturbance micro-expansion lightweight ultra-high performance concrete comprises the following steps:

[0089] S1. Mix 22 parts by weight of spherical gangue ceramsite and 7.2 parts by weight of crushed stone-shaped gangue ceramsite to obtain gangue ceramsite; add water to the gangue ceramsite, stir to pre-wet the gangue ceramsite, cover and place in a cool and dry place to stand, and obtain saturated pre-wet gangue ceramsite; wherein the mass of water is 13% of the mass of the gangue ceramsite;

[0090] S2, pour 37 parts by weight of cement, 7.8 parts of silica fume, 7 parts of fly ash microspheres, 2.6 parts of expansion agent, and 1.3 parts of calcium carbonate whisker into a mixer and mix at a speed of 35±2r / min for 3 minutes to obtain a premix;

[0091] S3, pouring the saturated pre-wetted coal gangue ceramsite in S1 into the premix, stirring to obtain a mixture;

[0092] S4. Add 0.06 parts by weight of nano-cellulose and 1.2 parts of polycarboxylate water reducer to 8.0 parts of water. After stirring evenly, pour it into the mixture in S3 and stir thoroughly at a speed of 35±2 r / min for 5 min to obtain a mixed slurry.

[0093] S5. Evenly add 6.5 parts by weight of steel fiber and 0.06 parts by weight of temperature shrinkage notched fiber to the mixed slurry in S4, stir thoroughly at a speed of 35±2 r / min for 4 min, and after stirring evenly, pour it into a mold, cover it with a film and cure for 24 h, then remove the mold, and then carry out standard curing (at a temperature of 20°C and a relative humidity of 98%RH, cure for 28 d) to obtain the anti-disturbance slightly expanding lightweight ultra-high performance concrete.

[0094] Example 3

[0095] This application example provides an anti-disturbance slightly expanding lightweight ultra-high performance concrete, which includes the following raw materials in parts by weight: 36 parts of cement, 6 parts of fly ash microspheres, 7.0 parts of silica fume, 1.15 parts of silicon carbide whiskers, 0.07 parts of nano-cellulose, 24 parts of spherical coal gangue ceramsite, 5.7 parts of crushed coal gangue ceramsite, 2.3 parts of expansive agent, 0.04 parts of temperature shrinkage notched fiber, 6.3 parts of steel fiber, 1.4 parts of polycarboxylate water reducer, and 8.8 parts of water.

[0096] The preparation method of the above anti-disturbance slightly expanding lightweight ultra-high performance concrete includes the following steps:

[0097] S1. Mix 24 parts by weight of spherical coal gangue ceramsite and 5.7 parts of crushed coal gangue ceramsite to obtain coal gangue ceramsite; add water to the coal gangue ceramsite and stir to pre-wet the coal gangue ceramsite, cover it and place it in a cool and dry place to stand to obtain saturated pre-wet coal gangue ceramsite; wherein, the mass of water is 13% of the mass of the coal gangue ceramsite.

[0098] S2. Pour 36 parts by weight of cement, 7.0 parts of silica fume, 6 parts of fly ash microspheres, 2.3 parts of expansive agent, and 1.15 parts of calcium carbonate whiskers into a mixer and mix at a speed of 35±2 r / min for 3 min to obtain a premix.

[0099] S3. Pour the saturated pre-wet coal gangue ceramsite in S1 into the premix and stir to obtain a mixture.

[0100] S4. Add 0.07 parts by weight of nano-cellulose and 1.4 parts of polycarboxylate water reducer to 8.8 parts of water. After stirring evenly, pour it into the mixture in S3 and stir thoroughly at a speed of 35±2 r / min for 5 min to obtain a mixed slurry.

[0101] S5. Uniformly add 6.3 parts by weight of steel fibers and 0.04 parts by weight of temperature shrinkage grooved fibers to the mixed slurry in S4, stir thoroughly at a speed of 35 ± 2 r / min for 4 min, load into a mold after stirring evenly, remove the mold after curing with a film covering for 24 h, and then carry out standard curing (at a temperature of 20 °C and a relative humidity of 98% RH for 28 d) to obtain the anti-disturbance slightly expanding lightweight ultra-high performance concrete.

[0102] Comparative Example 1

[0103] This comparative example provides a commercially available C50 anti-disturbance concrete, including the following raw materials in parts by weight: 14 parts of cement, 4 parts of fly ash, 3.2 parts of slag powder, 42.5 parts of crushed stone, 31.2 parts of river sand, 2.0 parts of polycarboxylate water reducer, and 6.1 parts of water.

[0104] The preparation method of the C50 anti-disturbance concrete provided in the above comparative example includes the following steps:

[0105] S1. Pour cement, fly ash, slag powder, crushed stone, and river sand into a mixer and mix at a speed of 35 r / min for 3 min to obtain a premix;

[0106] S2. Add polycarboxylate water reducer and water to the premix obtained in S1, stir thoroughly at a speed of 35 r / min for 5 min to obtain C50 anti-disturbance concrete.

[0107] Comparative Example 2

[0108] This comparative example provides a common UHPC material containing quartz sand, including the following raw materials in parts by weight: 33.2 parts of cement, 6.2 parts of fly ash microspheres, 7.0 parts of silica fume, 40.8 parts of quartz sand, 6.1 parts of steel fibers, 2.3 parts of expansion agent, 1.2 parts of polycarboxylate water reducer, and 7.2 parts of water.

[0109] The preparation method of the common UHPC material containing quartz sand provided in the above comparative example includes the following steps:

[0110] S1. Pour cement, fly ash microspheres, silica fume, and quartz sand into a mixer and mix at a speed of 35 r / min for 3 min to obtain a premix;

[0111] S2. Add polycarboxylate water reducer, expansion agent, and water to the premix obtained in S1, stir thoroughly at a speed of 35 r / min for 5 min to obtain a mixed slurry;

[0112] S3. Uniformly add steel fibers to the mixed slurry obtained in S2, stir thoroughly at a speed of 35 r / min for 5 min to obtain a common UHPC material.

[0113] Comparative Example 3

[0114] This comparative example provides a lightweight ultra-high performance concrete containing shale lightweight aggregate (continuous grading of particle size 0.075-4.75 mm, water absorption rate 5.8%) with the same strength grade as the coal gangue material in Example 1, comprising the following raw materials in parts by weight: 37.0 parts of cement, 6.0 parts of fly ash microspheres, 7.0 parts of silica fume, 31.0 parts of crushed stone shale ceramsite, 6.3 parts of steel fiber, 2.5 parts of expansion agent, 1.4 parts of polycarboxylate water reducer, and 8.8 parts of water.

[0115] The method for preparing the lightweight ultra-high performance concrete provided in the above comparative example comprises the following steps:

[0116] S1, placing 31.0 parts by weight of crushed stone-shaped shale ceramsite in a nylon bag, soaking it in water for 24 hours, then taking it out and draining it to a saturated surface dry state to obtain pre-wet shale ceramsite;

[0117] S2, pouring 37.0 parts by weight of cement, 7.0 parts of silica fume, 6.0 parts of fly ash microspheres, 2.5 parts of expansion agent and the pre-wetted shale ceramsite obtained in S1 into a mixer and mixing at a speed of 35 r / min for 3 minutes to obtain a premix;

[0118] S3, adding 1.4 parts by weight of a polycarboxylate water-reducing agent and 8.8 parts of water into the premix obtained in S2, and stirring at a speed of 35 r / min for 5 min to obtain a mixed slurry;

[0119] S4. Add steel fiber to the mixed slurry in S3, stir it thoroughly at a speed of 35r / min for 4 minutes, put it into a mold after stirring evenly, cover it with a film and cure it for 24 hours to obtain ultra-high performance concrete containing shale expanded clay.

[0120] Performance Testing

[0121] The performance of the disturbance-resistant micro-expansion lightweight ultra-high performance concrete prepared in Examples 1 to 3 and the concrete in Comparative Examples 1 to 3 was tested, wherein the ratio of the strength after disturbance to the strength without disturbance was defined as the disturbance-resistant strength retention rate, and the test results are shown in Tables 1 to 3.

[0122] It can be seen from Table 1 that the anti-disturbance micro-expansion lightweight ultra-high performance concrete obtained by the present invention has the advantages of light weight, high strength, high anti-disturbance, and micro-expansion. As shown in Examples 1 to 3, the apparent density of the anti-disturbance micro-expansion lightweight ultra-high performance concrete obtained is ≤2050kg / m 3 , slump flowability 560-660mm, compressive strength up to 120MPa or more, and excellent bonding performance and bending and tensile performance. Compared with comparative examples 1-3, it can be seen that the anti-disturbance micro-expansion lightweight ultra-high performance concrete of the present invention has good volume stability and its own weight is significantly reduced.

[0123] Table 1 - Concrete properties of examples and comparative examples under the undisturbed state

[0124]

[0125] Table 2 - Compressive strength of concrete (MPa) of examples and comparative examples under different disturbance states

[0126]

[0127]

[0128] Note: The values in brackets are the ratios of the concrete strength at each age under different traffic load disturbances to the strength of the undisturbed concrete (i.e., the anti-disturbance strength retention rate).

[0129] As shown in Table 2, under the action of light traffic load disturbances, all examples and comparative examples showed excellent anti-disturbance effects; however, under medium traffic load, the examples still showed signs of enhancement at each age, while each comparative example gradually showed a decreasing trend. The reason for the above phenomenon is that the lightweight ultra-high performance concrete incorporated with whiskers, temperature shrinkage grooved fibers and nanocellulose in the present invention has good anti-disturbance performance, and at the same time, the optimization of the viscosity of the lightweight ultra-high performance concrete paste by spherical and crushed coal gangue ceramsite makes it have a stronger effect of resisting external disturbances. In addition, under heavy traffic load disturbances, the internal structure of the examples suffered microcrack damage due to severe disturbances, so the compressive strength retention rate decreased significantly in the early stage (3 h), but in the later stage, the damage of the micro-structure was repaired under the micro-crack healing effect of nanocellulose and the internal curing effect of saturated pre-wetted coal gangue lightweight aggregate, so the strength retention rate in the later stage (28 d) was significantly improved, and the strength only decreased by less than 3% compared with the undisturbed state. Different from the examples, under heavy traffic load disturbances, the strength retention rate of the comparative examples decreased by nearly 20% at most, so its anti-strong disturbance performance is poor. It should be noted that although the ultra-high performance concrete still has a relatively high strength (>120 MPa) under heavy traffic load disturbances, compared with the non-vibrated group, its strength decreased significantly (by 17.0%), so its anti-heavy traffic disturbance performance is poor.

[0130] Table 3 - Flexural tensile and bond strength of concrete (MPa) of examples and comparative examples under different disturbance states

[0131]

[0132]

[0133] Note: The values in brackets are the ratios of the concrete strength under different traffic load disturbances to the strength of the undisturbed concrete (i.e., the anti-disturbance strength retention rate).

[0134] As shown in Table 3, the flexural tensile strength and bonding strength of each embodiment are relatively excellent under different degrees of traffic load (the minimum anti-disturbance strength retention rate is still >95%); while the flexural tensile and bonding properties of the comparative example are significantly reduced under medium and heavy traffic load disturbances (especially under heavy traffic loads, the flexural tensile strength is reduced by nearly 20% at most, and the bonding strength is reduced by nearly 30% at most); the above test results show that the anti-disturbance micro-expansion lightweight ultra-high performance concrete obtained by the present invention can resist heavy traffic load disturbances, and its excellent flexural tensile and bonding properties are of great significance to improving the service life of concrete bridges.

[0135] In summary, the anti-disturbance micro-expansion lightweight ultra-high performance concrete of the present invention has the properties of high anti-disturbance, high fluidity, high toughness, good volume stability, strong bonding performance and reasonable construction operation time, and therefore has important practical application value. It has a wide range of applications. When applied to the repair, reinforcement and widening of bridges, roads and other projects, it can not only carry out large-scale uninterrupted traffic construction and effectively relieve traffic pressure, but also effectively reduce the deadweight of the concrete structure and reduce the pressure on the original bridge bearing capacity. At the same time, it solves the problem of high fluidity and high anti-disturbance performance of concrete, and has important guiding significance for the development and promotion of lightweight ultra-high performance concrete.

[0136] It can be understood that the technical features of the above-described embodiments can be arbitrarily combined. In order to make the description concise, not all possible combinations of the technical features in the above-described embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0137] The above are only preferred embodiments of the present application, and only specifically describe the technical principles of the present application. These descriptions are only for explaining the principles of the present application and cannot be interpreted as limiting the scope of protection of the present application in any way. Based on the explanation here, any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application, and other specific implementation methods of the present application that can be associated with the technicians in this field without creative work, should be included in the scope of protection of the present application.

Claims

1. A disturbance-resistant micro-expansion lightweight ultra-high performance concrete, characterized in that: The invention comprises the following raw materials in parts by weight: 36-39 parts of cement, 6-7 parts of fly ash microbeads, 7-8.6 parts of silica fume, 1.15-1.5 parts of whiskers, 0.07-0.09 parts of nanocellulose, 18-24 parts of spherical gangue ceramsite, 5.7-10 parts of crushed stone gangue ceramsite, 2.3-3.0 parts of expansion agent, 0.04-0.08 parts of temperature shrinkage notched fiber, 6.3-6.7 parts of steel fiber, 1.1-1.4 parts of water reducer, and 7.3-8.8 parts of water; The spherical coal gangue ceramsite and the crushed stone coal gangue ceramsite are continuously graded from 0.075 to 4.75 mm; The spherical gangue ceramsite and the crushed stone gangue ceramsite have a fineness modulus of 3.1-3.7, a cylinder pressure strength of ≥12.0MPa, and a bulk density of 700-900kg / m 3 , apparent density is 1500~1700kg / m 3 , saturated surface dry water absorption rate 12.0%~14.0%; The whiskers are silicon carbide whiskers; The nanocellulose is cellulose nanofibers; The cellulose nanofibers are 1-10 μm long, 10-60 nm in diameter, and have a specific surface area of ​​100-130 m 2 / kg; The preparation method of the temperature-shrinkage notched fiber comprises the following steps: 1) Two extruders are used to extrude the heat shrinkable core material mixture and the heat shrinkable skin material mixture into a die head with two cavities, wherein the heat shrinkable skin material enters the cavity corresponding to the skin material, and the heat shrinkable core material enters the cavity corresponding to the core material. The materials in the two cavities converge at the position of the spinneret of the extruder, wherein the spinneret has an inner ring and an outer ring, the inner ring of the spinneret is connected to the cavity of the core material, and the outer ring of the spinneret is connected to the cavity of the skin material. The two molten materials are extruded through the spinneret and adhered together in the air, cooled by a cold water tank, and then drawn in hot water at 90 to 100° C. to form a composite fiber with a skin-core structure; Among them, in the heat shrinkable leather material mixture, each raw material and its mass percentage are: polyoxymethylene 97.5%, maleic anhydride grafted compatibilizer 1.5% and phthalate 1%; the extrusion pressure of the leather material cavity is 8MPa, and the melting temperature is maintained at 250℃; In the heat shrinkable core material mixture, the raw materials and their mass percentages are: polyester 98%, steel nucleating agent 2%, composed of dibenzylidene sorbitol and sodium benzoate in a mass ratio of 1:1; the extrusion pressure is 6MPa, and the melting temperature is maintained at 210°C; After the skin material and the core material are combined, they are extruded through a spinneret. The extrusion temperature of the two molten materials is 220°C and the extrusion pressure is 7MPa. The average diameter of the obtained core fiber is 0.15 mm, and the thickness of the skin fiber is 0.05 to 0.1 mm; 2) adding the obtained composite fiber to an octamethylcyclotetrasiloxane organosilicon solution for modification for 12 hours, and then drying and indenting the surface to increase the bonding performance with the concrete paste; 3) adding the obtained composite fiber to a modified polyvinyl alcohol solution with an expansion component added thereto for coating and modification for 24 hours, taking it out and drying it to prepare a temperature-shrinkage notched fiber; The modified polyvinyl alcohol solution is obtained by uniformly mixing a polyvinyl alcohol solution and a liquid expansion agent in a mass ratio of 7:3; The mass fraction of the polyvinyl alcohol solution is 5wt%; The method for preparing the anti-disturbance micro-expansion lightweight ultra-high performance concrete is characterized by comprising the following steps: S1. Mix 18-24 parts by weight of spherical gangue ceramsite and 5.7-10 parts by weight of crushed stone-shaped gangue ceramsite to obtain gangue ceramsite; add water to the gangue ceramsite, stir evenly to make the gangue ceramsite fully pre-wet, cover and place in a cool and dry place to stand, and obtain saturated pre-wetted gangue ceramsite; wherein the mass of water is 13% of the mass of the gangue ceramsite; S2, pour 36-39 parts by weight of cement, 7-8.6 parts of silica fume, 6-7 parts of fly ash microspheres, 2.3-3.0 parts of expansion agent, and 1.15-1.5 parts of whiskers into a mixer and mix to obtain a premix; S3, pouring the saturated pre-wetted coal gangue ceramsite in S1 into the premix, stirring to obtain a mixture; S4, adding 0.07-0.09 parts by weight of nanocellulose and 1.1-1.4 parts of a water reducing agent to 7.3-8.8 parts of water, stirring evenly, pouring into the mixture of S3, and stirring to obtain a mixed slurry; S5. 6.3-6.7 parts by weight of steel fiber and 0.04-0.08 parts by weight of temperature shrinkage notched fiber are uniformly added to the mixed slurry in S4, and the mixture is molded after stirring. After covering with a film and curing, the mold is removed, and then standard curing or steam curing is performed to obtain the disturbance-resistant micro-expansion lightweight ultra-high performance concrete.

2. The anti-disturbance micro-expansion lightweight ultra-high performance concrete according to claim 1, characterized in that: The fly ash microbeads have a loss on ignition of ≤3.0%, a water requirement ratio of ≤90%, and a spherical particle volume ratio of ≥95%.

3. The anti-disturbance micro-expansion lightweight ultra-high performance concrete according to claim 1, characterized in that: The silica fume has a SiO2 mass content of ≥95% and a specific surface area of ​​≥19500 m 2 / kg, 28d activity index ≥100%.

4. The anti-disturbance micro-expansion lightweight ultra-high performance concrete according to claim 1, characterized in that: The water reducing agent is a polycarboxylate-based high-efficiency water reducing agent.

5. The anti-disturbance micro-expansion lightweight ultra-high performance concrete according to claim 1, characterized in that: The specific surface area of ​​the expansion agent is ≥250 m 2 / kg, and limit the expansion rate to ≥0.035% for 7 days.

6. The anti-disturbance micro-expansion lightweight ultra-high performance concrete according to claim 1, characterized in that: The shrinkage rate of the temperature-shrinkage notched fiber is 0.5-12%, the response temperature is 30-100° C., the tensile strength is 500-1500 MPa, and the elastic modulus is 7-30 GPa.

7. A method for preparing the anti-disturbance micro-expansion lightweight ultra-high performance concrete according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Mix 18-24 parts by weight of spherical gangue ceramsite and 5.7-10 parts by weight of crushed stone-shaped gangue ceramsite to obtain gangue ceramsite; add water to the gangue ceramsite, stir evenly to make the gangue ceramsite fully pre-wet, cover and place in a cool and dry place to stand, and obtain saturated pre-wetted gangue ceramsite; wherein the mass of water is 13% of the mass of the gangue ceramsite; S2, pour 36-39 parts by weight of cement, 7-8.6 parts of silica fume, 6-7 parts of fly ash microspheres, 2.3-3.0 parts of expansion agent, and 1.15-1.5 parts of whiskers into a mixer and mix to obtain a premix; S3, pouring the saturated pre-wetted coal gangue ceramsite in S1 into the premix, stirring to obtain a mixture; S4, adding 0.07-0.09 parts by weight of nanocellulose and 1.1-1.4 parts of a water reducing agent to 7.3-8.8 parts of water, stirring evenly, pouring into the mixture of S3, and stirring to obtain a mixed slurry; S5. 6.3-6.7 parts by weight of steel fiber and 0.04-0.08 parts by weight of temperature shrinkage notched fiber are uniformly added to the mixed slurry in S4, and the mixture is molded after stirring. After covering with a film and curing, the mold is removed, and then standard curing or steam curing is performed to obtain the disturbance-resistant micro-expansion lightweight ultra-high performance concrete.

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