Spraying ultra-high performance concrete and preparation method thereof

Abstract

The invention discloses spraying ultra-high performance concrete and a preparation method thereof, and belongs to the technical field of concrete preparation, the spraying ultra-high performance concrete comprises the following raw materials by weight: 840 parts of cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 840-1080 parts of fine aggregate, 240 parts of water, 8.4 parts of a water reducer and 156 parts of steel fiber; the fine aggregate comprises machine-made sand and steel slag, the mass ratio of the machine-made sand to the steel slag is 1: (0-3), and the dosage of the steel slag is not 0. The prepared sprayed ultra-high performance concrete overcomes the defects that traditional sprayed concrete is low in strength and poor in toughness and durability, and environmental pollution caused by building construction is relieved; the springback rate is reduced, the one-time spraying layer thickness is increased, the performance of sprayed concrete is improved, then the engineering quality is effectively improved, material waste is reduced, and cost is reduced.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of concrete preparation, and particularly relates to a sprayed ultra-high performance concrete and a preparation method thereof. BACKGROUND

[0002] As a kind of efficient construction technology, the sprayed concrete technology has been widely used in many fields such as infrastructure, tunnel, mine, slope protection, etc. Its core advantage lies in rapid setting, large-area covering complex surface, and strong adhesion and initial strength. However, the ordinary sprayed concrete has the problems of poor toughness, low tensile strength, high permeability and low one-time spraying thickness, etc. In the long-term use process, it is easy to produce cracking, shrinkage defects, and has relatively poor durability.

[0003] With the increasing complexity of modern engineering requirements and the increasing construction requirements in extreme environments, sprayed ultra-high performance concrete has gradually attracted attention. The emergence of sprayed ultra-high performance concrete effectively makes up for the shortcomings of traditional sprayed concrete. By introducing high-efficiency water-reducing agents, mineral admixtures and fiber materials, etc., the mechanical properties, durability and workability are significantly improved. By optimizing the mix proportion and adding high-efficiency water-reducing agents, silica fume, fly ash and other mineral admixtures, the density and strength of the sprayed ultra-high performance concrete are significantly improved, and it shows more excellent anti-permeability and anti-cracking performance. The sprayed ultra-high performance concrete introduces fiber reinforced materials such as steel fiber, glass fiber, polypropylene fiber, etc. These fiber materials can effectively improve the toughness of the concrete, reduce the risk of cracking, and improve the impact resistance. However, with the deepening of the concept of sustainable development, how to introduce environmentally friendly materials such as recycled aggregates (steel slag), low-carbon cement substitutes, etc. into the sprayed ultra-high performance concrete to reduce its carbon footprint is also an important research direction for future development. However, the composition of steel slag is complex and has large fluctuations, containing active components such as free calcium oxide (f-CaO) and free magnesium oxide (f-MgO), which may cause f-CaO and f-MgO to slowly hydrate to generate volume-expanding products during the subsequent hydration process of the concrete, causing stress concentration in the concrete, and severely limiting the amount of steel slag added to the concrete and the application range. And the surface of the steel slag aggregate is often attached with a layer of loose iron oxide skin, which makes it difficult for the steel slag and the cement stone to form a tight interfacial transition zone, causing the interfacial transition zone to become a weak link of the concrete, which is prone to interfacial peeling under external force, affecting the overall mechanical properties of the concrete.

[0004] Therefore, how to add steel slag as aggregate to the concrete to prepare a sprayed ultra-high performance concrete with high strength, strong adhesion, less cracking and shrinkage, and high one-time spraying thickness is a technical problem that needs to be solved by those skilled in the art. SUMMARY

[0005] In view of the above technical problems, the present application provides a kind of jetting super high performance concrete and its preparation method.

[0006] To achieve the above object, the present application provides the following technical solutions:

[0007] A kind of jetting super high performance concrete, according to weight fraction, including the following raw materials:

[0008] 840 parts of cement, 120 parts of fly ash, 120 parts of silica ash, 120 parts of metakaolin, 840-1080 parts of fine aggregate, 240 parts of water, 8.4 parts of water reducing agent and 156 parts of steel fiber;

[0009] The fine aggregate includes machine-made sand and steel slag, wherein the mass ratio of machine-made sand and steel slag is 1: (0-3), and the amount of steel slag is not 0.

[0010] The present application uses steel slag to replace part of machine-made sand to prepare jetting super high performance concrete, and the main components of steel slag are dicalcium silicate, tricalcium silicate, tricalcium aluminate and iron oxide, etc., which have certain potential hydraulicity, and the surface of steel slag is rough and angular, with high internal friction angle and large specific surface area, which can significantly increase the interfacial bonding force between cement matrix and aggregate, further improve the mechanical properties of concrete, so it can be used as fine aggregate in concrete research. In addition, the preparation of concrete using steel slag as aggregate digests industrial solid waste, reduces land occupation and pollution risk. It saves the non-renewable natural sand and stone resources and protects the natural environment. High-performance green concrete products are produced, and the amount of heavy metals is fixed (i.e. the high-performance green concrete prepared by using steel slag as aggregate not only meets the performance standards, but also fixes the heavy metals in the steel slag, so that the heavy metal ions are stably bound in the microstructure of the concrete, reducing the environmental release risk, ultimately realizing the low-carbon environmental protection and sustainability of the whole life cycle of the concrete), significantly reducing the environmental load of the whole life cycle, which is a typical low-carbon, environmentally friendly and sustainable green building material technology.

[0011] Optionally, the mass ratio of machine-made sand and steel slag is 3:1, 1:1 or 1:3.

[0012] Further, the particle size of the steel slag is 0.15-1.18 mm; according to mass percentage, it includes the following components:

[0013] 24.5% Fe, 48.5% CaO, 12.1% SiO2, 6.9% MgO, 4.5% Al2O3, 1.55% P2O5 and 0.79% ZrO2, and the balance is ash.

[0014] Steel slag, as a byproduct of steel production, is a challenge for waste disposal due to its large output and complex composition. The present invention uses it as one of the raw materials for shotcrete ultra-high performance concrete because: 1. Steel slag has a rough surface and sharp corners, with a high internal friction angle and a large specific surface area, which can significantly increase the interfacial bonding force between the cement matrix and the aggregate, further improving the mechanical properties of the concrete. 2. The high density and low porosity of steel slag aggregate improve the overall density of the concrete, effectively reducing the penetration of water and harmful substances. 3. From the aspects of environmental characteristics and economic benefits, the use of steel slag not only helps to reduce waste accumulation and reduce environmental pollution risk, but also saves natural resources.

[0015] In summary, the present invention uses steel slag processed to a target particle size of 0.15-1.18 mm, which can further strengthen the volume stability control and ensure the uniformity of particle size distribution.

[0016] Further, the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%.

[0017] Optionally, the steel fiber is a round-section end straight type copper-plated steel fiber or a round-section end hook type copper-plated steel fiber.

[0018] The present invention uses steel fiber as one of the raw materials for preparing shotcrete ultra-high performance concrete. Steel fiber inhibits the development of concrete damage by bridging cracks, deflecting crack propagation paths, and optimizing the interface transition zone (reducing ITZ thickness). Steel fiber forms a three-dimensional "bridge network" inside the concrete, transforming brittle concrete into a high-strength, high-toughness, and high-durability composite material: it significantly enhances tensile, bending, shear, and impact resistance, effectively blocks and controls crack width, thereby simultaneously improving the concrete's seismic, fatigue, frost penetration, and long-term durability. It can be used for bridges, tunnels, airports, and high-seismicity engineering projects.

[0019] Further, the tensile strength of the steel fiber is ≥2400MPa.

[0020] Further, the steel fiber is a round-section end hook type copper-plated steel fiber.

[0021] Optionally, the cement is P.O 52.5 cement with a loss on ignition ≤1.55%.

[0022] Optionally, the fly ash is grade I fly ash with a loss on ignition ≤6% and a strength activity index ≥70%.

[0023] Optionally, the silica fume has a SiO2 content ≥94%, an alkali content ≤1.5%, an activity index ≥115%, and a loss on ignition ≤3%.

[0024] Optionally, the metakaolin has a SiO2 content of 52-56%, an Al2O3 content of 41-45%, a 7-day activity index of ≥110%, and a 28-day activity index of ≥120%.

[0025] Optionally, the water reducing agent is at least one of a lignosulfonate water reducing agent, a naphthalene water reducing agent, a melamine water reducing agent, an aminosulfonate water reducing agent, an aliphatic water reducing agent, or a polycarboxylic acid water reducing agent.

[0026] Further, the water reducing agent is a polycarboxylic acid water reducing agent, has a density of 1.01-1.05 g / cm3, a pH value of 6.8, a water-reducing rate of ≥45%, and an air content of ≤6.0%. 3

[0027] The present application utilizes the high-efficiency dispersion performance of a polycarboxylic acid water reducing agent to achieve a leap in the performance of concrete. It produces a strong steric hindrance effect between cement particles due to its unique molecular structure, fully disperses the cement particles, and thus greatly reduces the mixing water consumption while imparting excellent high fluidity and self-compacting properties to the concrete. This not only significantly reduces the water-binder ratio, makes the concrete obtain higher mechanical strength and a denser microstructure, greatly improves the durability, but also effectively controls the cement hydration process, and maintains the workability of the concrete for a long time. In addition, it has good adaptability to various cementitious materials, has the characteristics of low dosage and high environmental protection, and is a key technology for preparing high-performance concrete and realizing the resource utilization of industrial solid waste.

[0028] The preparation method of the sprayed ultra-high performance concrete described above comprises the following steps:

[0029] (1) cement, fly ash, silica fume, metakaolin, and fine aggregate are mixed, and then steel fibers are added to obtain a dry mixture of sprayed ultra-high performance concrete;

[0030] (2) a water reducing agent and water are mixed and then added to the dry mixture of sprayed ultra-high performance concrete to form a slurry, and the slurry is sprayed onto a sprayed surface to obtain the sprayed ultra-high performance concrete.

[0031] Optionally, in step (2), the thickness of a single spraying is 14-16 cm.

[0032] Compared with the prior art, the present application has the following advantages and technical effects:

[0033] ​The application effectively reduces the porosity inside the concrete and reduces the defects caused by the weak interface between the aggregate and the paste by removing the coarse aggregate when preparing the sprayed ultra-high performance concrete (UHPC). The compactness of the matrix is greatly improved, and a high-density microstructure based on the closest packing theory is achieved. This structure optimization significantly improves the strength, toughness and durability of the concrete, while the rebound rate is significantly reduced. In addition, the improved concrete has enhanced cohesiveness, and the thickness of the sprayed layer is increased, which is more conducive to the smoothing construction of the sprayed layer surface.

[0034] The application applies steel slag as fine aggregate in concrete, which can produce many beneficial effects, and has the dual advantages of performance improvement and environmental protection. In terms of mechanical properties, the steel slag aggregate can significantly improve the strength and wear resistance of the concrete. Due to the solid and high hardness characteristics of the steel slag, the compressive strength and wear resistance of the concrete are enhanced. In addition, the surface of the steel slag particles is rough and angular, which can produce a more secure mechanical engagement with the cement paste, optimizing the structure of the interfacial transition zone (ITZ) and further improving the overall mechanical properties. The sprayed ultra-high performance concrete prepared by the application improves the defects of low strength, poor toughness and durability of traditional sprayed concrete, and can be widely applied in the field of tunnel lining, and relieves the pollution of the environment caused by building construction. DETAILED DESCRIPTION

[0035] Various exemplary embodiments of the present application will now be described in detail with reference to the drawings. The detailed description, which should be considered in conjunction with the accompanying figures, is intended to describe only certain aspects of the application and is not intended to limit the application in any way. Rather, the following description should be considered in a descriptive sense only and not intended to imply any particular ordering or sequence of the steps described herein.

[0036] It should be understood that the terms described in the present application are only for the description of the specific embodiments and are not intended to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the stated range and any other stated value or intermediate value within the stated range is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0037] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are concerned. In the event of any conflict between the content of this specification and any document incorporated by reference, the content of this specification will control.

[0038] Many modifications and variations to the illustrative embodiments described herein will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. Additional embodiments of the technology will be apparent to those skilled in the art from consideration of the specification and practice of the subject technology. The specification and examples given herein are by way of illustration only and are not intended to limit the scope of the subject technology.

[0039] As used herein, the terms "comprise", "comprising", "include", "including", "have", "having" or the like are open-ended and allow for elements, components, etc., not expressly listed to be present.

[0040] The embodiment of the present application provides a kind of steel slag aggregate jetting ultra-high performance concrete, according to weight fraction, including the following raw materials:

[0041] 840 parts of cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 210-1080 parts of machine-made sand, 0-810 parts of steel slag, 240 parts of water, 8.4 parts of water reducing agent and 156 parts of steel fiber.

[0042] In some optional embodiments, the cement is P.O 52.5 cement, and the loss on ignition is less than or equal to 5%;

[0043] The fly ash is grade I fly ash, and the loss on ignition is less than or equal to 6%, and the strength activity index is greater than or equal to 70%;

[0044] The silica fume contains SiO2 in an amount greater than or equal to 94%, contains alkali in an amount less than or equal to 1.5%, has an activity index greater than or equal to 115%, and has a loss on ignition less than or equal to 3%;

[0045] The metakaolin contains SiO2 in an amount of 52-56%, contains Al2O3 in an amount of 41-45%, has a 7-day activity index greater than or equal to 110%, and has a 28-day activity index greater than or equal to 120%;

[0046] The machine-made sand has a particle size of 0.15-1.18 mm, a fineness modulus of 2.66, and a stone powder content less than or equal to 2%;

[0047] The steel slag has a particle size of 0.15-1.18 mm, and contains 24.5% Fe, 48.5% CaO, 12.1% SiO2, 6.9% MgO, 4.5% Al2O3, 1.55% P2O5, and 0.79% ZrO2; and the steel fiber is a round-section end-straight type copper-plated steel fiber or a round-section end-hook type copper-plated steel fiber with a tensile strength greater than or equal to 2400 MPa.

[0048] In some optional embodiments, the water reducing agent is one or any combination of a lignosulfonate type water reducing agent, a naphthalene type water reducing agent, a melamine type water reducing agent, an aminosulfonate type water reducing agent, an aliphatic type water reducing agent, or a polycarboxylic acid type water reducing agent.

[0049] In some optional embodiments, the water reducing agent is a polycarboxylic acid type water reducing agent, and has a density of 1.01-1.05 g / cm3 , and the pH value is 6.8, the water-reducing rate is greater than or equal to 45%, and the air content is less than or equal to 6.0%.

[0050] The application further provides a preparation method of the steel slag aggregate-containing sprayed ultra-high performance concrete.

[0051] (1) cement, fly ash, silica fume, metakaolin, machine-made sand and steel slag are mixed, and then steel fiber is added and mixed to obtain a dry mixture of the sprayed ultra-high performance concrete;

[0052] (2) the water-reducing agent and water are mixed and then added to the dry mixture of the sprayed ultra-high performance concrete to form a slurry, and the slurry is sprayed onto a sprayed surface to obtain the sprayed ultra-high performance concrete.

[0053] In some optional embodiments, the thickness of a single spraying in step (2) is 14-16 cm.

[0054] The application further provides an application of the steel slag aggregate-containing sprayed ultra-high performance concrete in tunnel lining.

[0055] In the application, “room temperature” refers to 20-30℃ unless otherwise specified.

[0056] In the application, “parts” refer to mass parts unless otherwise specified.

[0057] In the application, all raw materials are commercially available. The cement used in the examples is purchased from Jilin Yatai Cement Co., Ltd.; the fly ash is purchased from Lingshou County Shengyun Mineral Product Processing Factory; the silica fume is purchased from Lingshou County Shengyun Mineral Product Processing Factory; the metakaolin is purchased from Inner Mongolia Chaopai New Material Co., Ltd.; the machine-made sand is purchased from Jilin Province Qingfeng Mining; the steel slag is purchased from Shijiazhuang Xuhuan New Material Technology Co., Ltd.; the steel fiber is purchased from Liaocheng Hongshengyuan Metal Products Co., Ltd.; and the water-reducing agent is purchased from Sichuan Dongrunbaisheng New Material Co., Ltd.

[0058] In the following examples and comparative examples, the water-reducing agent is a polycarboxylic acid type water-reducing agent, and the density of the polycarboxylic acid type water-reducing agent is 1.01-1.05 g / cm 3 , the pH value is 6.8, the water-reducing rate is greater than or equal to 45%, and the air content is less than or equal to 6.0%.

[0059] The steel slag includes the following components in terms of mass percentage:

[0060] 24.5% Fe, 48.5% CaO, 12.1% SiO2, 6.9% MgO, 4.5% Al2O3, 1.55% P2O5 and 0.79% ZrO2.

[0061] The technical solutions of the application are further described through the following examples.

[0062] Example 1

[0063] A preparation method of a sprayed ultra-high performance concrete, comprising the following steps:

[0064] (1) accurately weighing 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin and 840 parts of machine-made sand for mixing, then adding 156 parts of steel fiber for mixing again, to obtain a dry mixture of the sprayed ultra-high performance concrete;

[0065] wherein the P.O 52.5 cement has a loss on ignition ≤3.5%; the fly ash is grade I fly ash, with a loss on ignition ≤6% and a strength activity index ≥70%; the silica fume has a SiO2 content ≥94%, an alkali content ≤1.5%, an activity index ≥115% and a loss on ignition ≤3%; the metakaolin has a SiO2 content of 52-56%, an Al2O3 content of 41-45%, a 7-day activity index ≥110% and a 28-day activity index ≥120%; the machine-made sand has a particle size of 0.15-1.18 mm, a fineness modulus of 2.66 and a stone powder content ≤2%; and the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength ≥2400 MPa.

[0066] (2) accurately weighing 8.4 parts of a water reducing agent, then mixing the water reducing agent with 240 parts of water to prepare a mixed solution, adding the mixed solution to the dry mixture of the sprayed ultra-high performance concrete to form a slurry, and finally spraying the slurry onto a sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0067] Example 2

[0068] A preparation method of a sprayed ultra-high performance concrete containing steel slag aggregate, comprising the following steps:

[0069] (1) accurately weighing 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 630 parts of machine-made sand and 210 parts of steel slag for mixing, then adding 156 parts of steel fiber for mixing again, to obtain a dry mixture of the sprayed ultra-high performance concrete; wherein the P.O 52.5 cement has a loss on ignition ≤3.5%; the fly ash is grade I fly ash, with a loss on ignition ≤6% and a strength activity index ≥70%; the silica fume has a SiO2 content ≥94%, an alkali content ≤1.5%, an activity index ≥115% and a loss on ignition ≤3%; the metakaolin has a SiO2 content of 52-56%, an Al2O3 content of 41-45%, a 7-day activity index ≥110% and a 28-day activity index ≥120%; the machine-made sand has a particle size of 0.15-1.18 mm, a fineness modulus of 2.66 and a stone powder content ≤2%; and the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength ≥2400 MPa.

[0070] (2) accurately take 8.4 parts of water reducing agent, then mixed with 240 parts of water to prepare a mixed solution, then the mixed solution is added to the above-mentioned dry mixture of sprayed ultra-high performance concrete to form a slurry, and finally the slurry is sprayed on the sprayed surface, and the sprayed ultra-high performance concrete is obtained after setting.

[0071] Example 3

[0072] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0073] (1) accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 420 parts of machine-made sand and 420 parts of steel slag, and then add 156 parts of steel fiber to mix again to obtain a dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength of ≥2400 MPa.

[0074] (2) accurately take 8.4 parts of water reducing agent, then mixed with 240 parts of water to prepare a mixed solution, then the mixed solution is added to the above-mentioned dry mixture of sprayed ultra-high performance concrete to form a slurry, and finally the slurry is sprayed on the sprayed surface, and the sprayed ultra-high performance concrete is obtained after setting.

[0075] Example 4

[0076] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0077] (1) accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 210 parts of machine-made sand and 630 parts of steel slag for mixing, then add 156 parts of steel fiber for mixing again, to obtain the dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength of ≥2400 MPa.

[0078] (2) accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the dry mixture of sprayed ultra-high performance concrete to form a slurry, and finally spray the slurry onto the sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0079] Example 5

[0080] A preparation method of sprayed ultra-high performance concrete, comprising the following steps:

[0081] (1) accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin and 960 parts of machine-made sand for mixing, then add 156 parts of steel fiber for mixing again, to obtain the dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength of ≥2400 MPa.

[0082] (2) accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the dry mixture of sprayed ultra-high performance concrete to form a slurry, and finally spray the slurry onto the sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0083] Example 6

[0084] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0085] (1) accurately weigh 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 720 parts of machine-made sand and 240 parts of steel slag, mix them, then add 156 parts of steel fiber and mix again to obtain a dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength ≥2400 MPa.

[0086] (2) accurately weigh 8.4 parts of water reducing agent, then mix it with 240 parts of water to prepare a mixed solution, add the mixed solution to the dry mixture of sprayed ultra-high performance concrete to form a slurry, and finally spray the slurry onto the sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0087] Example 7

[0088] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0089] (1) accurately weigh 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 480 parts of machine-made sand and 480 parts of steel slag, mix them, then add 156 parts of steel fiber and mix again to obtain a dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength ≥2400 MPa.

[0090] (2) accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the above-mentioned dry mixture of sprayed ultra-high performance concrete to mix to form a slurry, finally spray the slurry on the sprayed surface, and the sprayed ultra-high performance concrete can be obtained after setting.

[0091] Example 8

[0092] A preparation method of a sprayed ultra-high performance concrete containing steel slag aggregate, comprising the following steps:

[0093] (1) accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 240 parts of machine-made sand and 720 parts of steel slag to mix, then add 156 parts of steel fiber to mix again, to obtain a dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength of ≥2400 MPa.

[0094] (2) accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the above-mentioned dry mixture of sprayed ultra-high performance concrete to mix to form a slurry, finally spray the slurry on the sprayed surface, and the sprayed ultra-high performance concrete can be obtained after setting.

[0095] Example 9

[0096] A preparation method of a sprayed ultra-high performance concrete, comprising the following steps:

[0097] (1) accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin and 1080 parts of machine-made sand to mix, then add 156 parts of steel fiber to mix again, to obtain the dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the silica fume has a SiO2 content of ≥94%, an alkali content of ≤1.5%, an activity index of ≥115%, and a loss on ignition of ≤3%; the metakaolin has a SiO2 content of 52-56% and an Al2O3 content of 41-45%, a 7-day activity index of ≥110%, and a 28-day activity index of ≥120%; the machine-made sand has a particle size of 0.15-1.18 mm, a fineness modulus of 2.66, and a stone powder content of ≤2%; and the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength of ≥2400 MPa.

[0098] (2) accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the dry mixture of sprayed ultra-high performance concrete to mix and form a slurry, and finally spray the slurry onto the sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0099] Example 10

[0100] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0101] (1) accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 810 parts of machine-made sand and 270 parts of steel slag to mix, then add 156 parts of steel fiber to mix again, to obtain the dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the silica fume has a SiO2 content of ≥94%, an alkali content of ≤1.5%, an activity index of ≥115%, and a loss on ignition of ≤3%; the metakaolin has a SiO2 content of 52-56% and an Al2O3 content of 41-45%, a 7-day activity index of ≥110%, and a 28-day activity index of ≥120%; the machine-made sand has a particle size of 0.15-1.18 mm, a fineness modulus of 2.66, and a stone powder content of ≤2%; and the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength of ≥2400 MPa.

[0102] (2) accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the dry mixture of sprayed ultra-high performance concrete to mix and form a slurry, and finally spray the slurry onto the sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0103] Example 11

[0104] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0105] (1) Accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 540 parts of machine-made sand and 540 parts of steel slag for mixing, then add 156 parts of steel fiber for mixing again to obtain a dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength ≥2400 MPa.

[0106] (2) Accurately take 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the dry mixture of the sprayed ultra-high performance concrete to form a slurry, and finally spray the slurry onto the sprayed surface to obtain the sprayed ultra-high performance concrete after setting.

[0107] Example 12

[0108] A preparation method of a steel slag aggregate-containing sprayed ultra-high performance concrete, comprising the following steps:

[0109] (1) Accurately take 840 parts of P.O 52.5 cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 540 parts of machine-made sand and 540 parts of steel slag for mixing, then add 156 parts of steel fiber for mixing again to obtain a dry mixture of sprayed ultra-high performance concrete; wherein the loss on ignition of P.O 52.5 cement is ≤3.5%; the fly ash is grade I fly ash, the loss on ignition is ≤6%, and the strength activity index is ≥70%; the SiO2 content in the silica fume is ≥94%, the alkali content is ≤1.5%, the activity index is ≥115%, and the loss on ignition is ≤3%; the SiO2 content in the metakaolin is 52-56%, the Al2O3 content is 41-45%, the 7-day activity index is ≥110%, and the 28-day activity index is ≥120%; the particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%; the steel fiber is a round cross-section end straight type copper-plated steel fiber with a tensile strength ≥2400 MPa.

[0110] (2) accurately weigh 8.4 parts of water reducing agent, then mix with 240 parts of water to prepare a mixed solution, then add the mixed solution to the above-mentioned dry mixture of sprayed ultra-high performance concrete to mix to form a slurry, and finally spray the slurry onto the sprayed surface, and the sprayed ultra-high performance concrete can be obtained after setting.

[0111] Example 13

[0112] A preparation method of sprayed ultra-high performance concrete, which is different from example 1 only in that the round cross-section straight type copper-plated steel fiber is replaced by equal weight parts of round cross-section hook type copper-plated steel fiber.

[0113] The remaining steps are the same as those in example 1.

[0114] Example 14

[0115] A preparation method of sprayed ultra-high performance concrete containing steel slag aggregate, which is different from example 2 only in that the round cross-section straight type copper-plated steel fiber is replaced by equal weight parts of round cross-section hook type copper-plated steel fiber.

[0116] The remaining steps are the same as those in example 2.

[0117] Example 15

[0118] A preparation method of sprayed ultra-high performance concrete containing steel slag aggregate, which is different from example 3 only in that the round cross-section straight type copper-plated steel fiber is replaced by equal weight parts of round cross-section hook type copper-plated steel fiber.

[0119] The remaining steps are the same as those in example 3.

[0120] Example 16

[0121] A preparation method of sprayed ultra-high performance concrete containing steel slag aggregate, which is different from example 4 only in that the round cross-section straight type copper-plated steel fiber is replaced by equal weight parts of round cross-section hook type copper-plated steel fiber.

[0122] The remaining steps are the same as those in example 4.

[0123] Example 17

[0124] A preparation method of sprayed ultra-high performance concrete, which is different from example 5 only in that the round cross-section straight type copper-plated steel fiber is replaced by equal weight parts of round cross-section hook type copper-plated steel fiber.

[0125] The remaining steps are the same as those in example 5.

[0126] Example 18

[0127] A preparation method of steel slag aggregate containing sprayed ultra-high performance concrete, the only difference from example 6 is that the round cross-section straight type copper-plated steel fiber is replaced by equal weight fraction of round cross-section hook type copper-plated steel fiber;

[0128] The remaining steps are the same as example 6.

[0129] Example 19

[0130] A preparation method of steel slag aggregate containing sprayed ultra-high performance concrete, the only difference from example 7 is that the round cross-section straight type copper-plated steel fiber is replaced by equal weight fraction of round cross-section hook type copper-plated steel fiber;

[0131] The remaining steps are the same as example 7.

[0132] Example 20

[0133] A preparation method of steel slag aggregate containing sprayed ultra-high performance concrete, the only difference from example 8 is that the round cross-section straight type copper-plated steel fiber is replaced by equal weight fraction of round cross-section hook type copper-plated steel fiber;

[0134] The remaining steps are the same as example 8.

[0135] Example 21

[0136] A preparation method of sprayed ultra-high performance concrete, the only difference from example 9 is that the round cross-section straight type copper-plated steel fiber is replaced by equal weight fraction of round cross-section hook type copper-plated steel fiber;

[0137] The remaining steps are the same as example 9.

[0138] Example 22

[0139] A preparation method of steel slag aggregate containing sprayed ultra-high performance concrete, the only difference from example 10 is that the round cross-section straight type copper-plated steel fiber is replaced by equal weight fraction of round cross-section hook type copper-plated steel fiber;

[0140] The remaining steps are the same as example 10.

[0141] Example 23

[0142] A preparation method of steel slag aggregate containing sprayed ultra-high performance concrete, the only difference from example 11 is that the round cross-section straight type copper-plated steel fiber is replaced by equal weight fraction of round cross-section hook type copper-plated steel fiber;

[0143] The remaining steps are the same as example 11.

[0144] Example 24

[0145] A preparation method of a steel slag aggregate containing sprayed ultra-high performance concrete, which is only different from example 12 in that the round cross-section end straight type copper-plated steel fiber is replaced by equal weight parts of round cross-section end hook type copper-plated steel fiber;

[0146] The remaining steps are the same as those in example 12.

[0147] Effect verification:

[0148] The slurry prepared in examples 1-24 is sprayed by a PT850 type wet coarse sand spraying machine manufactured by Hubei Huochetuan Ring Manufacturing Co., Ltd. to test the thickness of a single spraying, and then the initial setting time, final setting time, impermeability and leakage resistance, fluidity, compressive strength and 28-day splitting tensile strength of the sprayed ultra-high performance concrete prepared in examples 1-24 are tested according to JGJ / T 372 2016, GB / T 50080-2011, GB / T 50081-2019 and GB / T 50082-2009, wherein the compressive strength includes 1-day, 3-day, 7-day, 14-day and 28-day compressive strength, and the test results are shown in Tables 1 and 2.

[0149] Table 1

[0150]

[0151] Table 2

[0152]

[0153] As shown in Tables 1 and 2 above, the sprayed ultra-high performance concrete prepared by the preparation method of the present application has a fluidity of 14.2-15.8 cm, meeting the working performance requirements of sprayed concrete; the initial setting time is 21-27 min, and the final setting time is 178-193 min; the single spraying layer thickness can reach 14-15.6 cm; the impermeability is excellent; the sprayed ultra-high performance concrete prepared by the preparation method of the present application has a low rebound rate, high early and late strength, and excellent splitting tensile strength. The 28-day splitting tensile strength slowly decreases with the addition of steel slag, which is due to the introduction of a relatively weak interfacial transition zone. At a replacement rate of 25%, the initial decrease in strength is mainly due to the introduction of the relatively weak interfacial transition zone by steel slag, which serves as a preferential site for micro-crack initiation, weakening the integrity of the matrix. At a replacement rate of 50%, the mixed aggregate system reaches the best particle packing state and matrix uniformity, which maximizes the resistance to crack initiation, thereby overcoming the negative effects of weak interfaces and resulting in a peak strength. When the replacement rate increases to 75%, the interfacial transition zone is dominated by steel slag, which may cause local microstructure inhomogeneity due to its high water absorption, resulting in a slight decrease in the macroscopic strength of the splitting tensile test from the peak value.

[0154] The above merely provides the preferred embodiment of the present application, and the protection scope of the present application is not limited thereto. Any modification or replacement within the technical scope disclosed by the present application should be covered within the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A sprayed ultra-high performance concrete, characterized in that, According to weight parts, the following raw materials are included: 840 parts of cement, 120 parts of fly ash, 120 parts of silica fume, 120 parts of metakaolin, 840-1080 parts of fine aggregate, 240 parts of water, 8.4 parts of water reducing agent and 156 parts of steel fiber; The fine aggregate includes machine-made sand and steel slag, and the mass ratio of the machine-made sand and the steel slag is 1:(0-3), wherein the amount of the steel slag is not 0.

2. A shotcrete ultra-high performance concrete according to claim 1, characterized in that, The mass ratio of the machine-made sand and the steel slag is 3:1, 1:1 or 1:

3.

3. The shotcrete ultra-high performance concrete according to claim 1, wherein The particle size of the steel slag is 0.15-1.18 mm. According to mass percentage, the steel slag includes the following components: 24.5% Fe, 48.5% CaO, 12.1% SiO2, 6.9% MgO, 4.5% Al2O3, 1.55% P2O5 and 0.79% ZrO2, and the balance is ash.

4. The shotcrete ultra-high performance concrete of claim 1, wherein, The particle size of the machine-made sand is 0.15-1.18 mm, the fineness modulus is 2.66, and the stone powder content is ≤2%.

5. The shot super high performance concrete of claim 1, wherein, The steel fiber is selected from round cross-section end straight type copper-plated steel fiber or round cross-section end hook type copper-plated steel fiber.

6. A shot super high performance concrete according to claim 5, characterized in that, The steel fiber is round cross-section end hook type copper-plated steel fiber.

7. The shotcrete ultra-high performance concrete of claim 1, wherein, The cement is P.O 52.5 cement, and the loss on ignition is ≤1.55%; and / or, The fly ash is grade I fly ash, and the loss on ignition is ≤6% and the strength activity index is ≥70%; and / or, The silica fume has a SiO2 content of ≥94%, an alkali content of ≤1.5%, an activity index of ≥115% and a loss on ignition of ≤3%; and / or, The metakaolin has a SiO2 content of 52-56%, an Al2O3 content of 41-45%, a 7-day activity index of ≥110% and a 28-day activity index of ≥120%; and / or, The water reducing agent is selected from lignin sulfonate type water reducing agent, naphthalene type water reducing agent, melamine type water reducing agent, aminosulfonate type water reducing agent, aliphatic type water reducing agent or polycarboxylic acid type water reducing agent.

8. A shot super high performance concrete according to claim 7, characterized in that, The polycarboxylic acid-based water reducing agent has a density of 1.01-1.05 g / cm 3 , a pH value of 6.8, a water reducing rate of ≥45%, and an air content of ≤6.0%.

9. A method of preparing a shot ultra-high performance concrete according to any one of claims 1-8, characterized in that, The following steps are included: (1) cement, fly ash, silica fume, metakaolin, fine aggregate are mixed, and then steel fiber is added to obtain a dry mixture of sprayed ultra-high performance concrete; (2) the water reducing agent and water are mixed and added to the dry mixture of sprayed ultra-high performance concrete to form a slurry, which is then sprayed onto a sprayed surface to obtain the sprayed ultra-high performance concrete.

10. The method of preparing a sprayed ultra-high performance concrete according to claim 9, characterized in that, In step (2), the thickness of a single spraying when sprayed onto the sprayed surface is 14-16 cm.

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