A high-strength, segregation-resistant self-compacting concrete, its preparation method, and its application.

Abstract

This invention provides a high-strength, anti-segregation self-compacting concrete, its preparation method, and its application, belonging to the field of tunnel and underground engineering technology. This invention utilizes steel fibers to prevent aggregate settlement, while polymer fibers tend to distribute in the upper slurry. Simultaneously, the surface structure of both steel and polymer fibers increases the mechanical interlocking force between the fibers and the slurry, effectively resisting the settling tendency of fibers and coarse aggregates. A cationic viscosity modifier imparts excellent thixotropic properties to the concrete, effectively locking in aggregates and moisture, preventing segregation, and achieving high flowability and high stability. Water glass reduces the impact of hardening shrinkage on concrete performance, improving its crack resistance and durability. Water glass also enhances the compatibility of aggregates with other raw materials. The "discontinuous gradation" strategy reduces the mechanical interlocking force of particles during mixing, causing a sharp drop in resistance during concrete flow, and then maintaining uniformity through frictional self-locking when stationary, thus improving its stability.

Description

Technical Field

[0001] This invention relates to the field of tunnel and underground engineering technology, and in particular to a high-strength, segregation-resistant, self-compacting concrete, its preparation method, and its application. Background Technology

[0002] In large-scale underground engineering projects (such as water diversion tunnels for hydropower stations, vertical shafts for pumped storage power stations, and foundations for large equipment), there are often abrupt changes in structural cross-sections, large pouring height differences (usually >5m), dense reinforcement, and narrow spaces. Traditional C60~C100 self-compacting concrete (SCC) faces severe challenges in such environments.

[0003] First, high strength and high fluidity are incompatible. To meet the strength requirements of C100 and above, the water-cement ratio of concrete needs to be reduced and the amount of adhesive needs to be increased. However, this will cause a sharp increase in viscosity, resulting in poor fluidity during the pouring process. Although using thickeners (such as cellulose ethers) can stabilize concrete, the addition of thickeners will significantly increase the yield stress and plastic viscosity, sacrificing fluidity and making it difficult to meet the high fluidity requirements of spread ≥650mm and T500≤3s.

[0004] Second, it lacks stability. During concrete pouring, the aggregate is prone to separation from the paste (segregation), with a segregation rate generally >5%, which can easily cause problems such as pipe blockage, pump blockage, and poor structural uniformity.

[0005] Third, vibration compaction presents difficulties and risks. In narrow, high-altitude structures, manual or mechanical vibration is difficult to implement, which can easily lead to defects such as missed vibration, cold joints, and honeycombing. Furthermore, the vibrator is prone to colliding with dense reinforcing bars, affecting the durability of the structure. Summary of the Invention

[0006] The purpose of this invention is to provide a high-strength anti-segregation self-compacting concrete, its preparation method, and its application. The high-strength anti-segregation self-compacting concrete provided by this invention has both high strength and high fluidity, meeting the high fluidity requirements of spread ≥650mm and T500≤3s. At the same time, it has a low segregation rate, good stability, and does not require vibration during use.

[0007] To achieve the above-mentioned objectives, the present invention provides the following technical solution: This invention provides a high-strength, anti-segregation, self-compacting concrete. The raw materials for preparing the high-strength, anti-segregation, self-compacting concrete, by weight, include: 230-280 parts of cement, 60-85 parts of fly ash microspheres, 30-55 parts of mineral powder, 35-90 parts of silica fume, 15-32 parts of water glass, 1600-1800 parts of aggregate, a viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, an expansion agent, composite fibers, and mixing water. The aggregate includes coarse aggregate and fine aggregate; the coarse aggregate has a particle size of 5-8 mm and 10-16 mm; the mass of the coarse aggregate with a particle size of 5-8 mm accounts for 65-75% of the total mass of the coarse aggregate; the fineness modulus of the fine aggregate is 2.6-3.0; the mass of the fine aggregate accounts for 40-42% of the total mass of the aggregate. The dosage of the viscosity-reducing polycarboxylate superplasticizer is 1.6-1.9% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. The cationic viscosity modifier comprises 0.1-0.13% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; the cationic charge density of the cationic viscosity modifier is 0.4-0.7 meq / g. The expansion agent comprises 8-10% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. The amount of composite fiber used is 0.2~0.5% of the total volume of high-strength anti-segregation self-compacting concrete; the composite fiber includes steel fiber and polymer fiber; the volume ratio of steel fiber to polymer fiber is (0.5~2):1; the shape of the composite fiber is one or more of the following: wavy, segmented structure and spiral. The water-cement ratio of the high-strength anti-segregation self-compacting concrete is 0.22~0.23.

[0008] Preferably, the fly ash microspheres are Class I fly ash microspheres with a water requirement ratio ≤ 92%; the particle size D50 of the fly ash microspheres is 1.5~2.5μm.

[0009] Preferably, the average particle size of the silica fume is 0.1~0.3μm; and the mass content of silica in the silica fume is 85~97%.

[0010] Preferably, the length of the steel fiber is 10-15 mm; the aspect ratio of the steel fiber is 60-70.

[0011] Preferably, the polymer fiber is made of polypropylene or polyethylene; the length of the polymer fiber is 25~60mm; and the diameter of the polymer fiber is 0.5~1.2mm.

[0012] Preferably, the expanding agent is a magnesium oxide expanding agent and a calcium sulfoaluminate-calcium oxide expanding agent; the mass content of the magnesium oxide expanding agent in the expanding agent is 20-35%.

[0013] Preferably, the magnesium oxide expanding agent contains ≥85% magnesium oxide by mass; the calcium sulfoaluminate-calcium oxide expanding agent contains 40-60% anhydrous calcium sulfoaluminate by mass; the calcium sulfoaluminate-calcium oxide expanding agent contains 20-40% calcium sulfate by mass; and the calcium sulfoaluminate-calcium oxide expanding agent contains 10-25% free calcium oxide by mass.

[0014] Preferably, the modulus of the water glass is 2.5 to 2.8.

[0015] This invention provides a method for preparing the high-strength, segregation-resistant, self-compacting concrete described in the above technical solution, comprising the following steps: Cement, fly ash microspheres, mineral powder, silica fume, composite fiber and expansion agent are mixed and then dry-mixed to obtain dry-mixed material; A viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, and a portion of mixing water are premixed to obtain an additive solution. The additive solution and the dry mixture are wet-mixed to obtain a slurry; Aggregates are added to the slurry, followed by water glass and the remaining mixing water, to obtain high-strength, segregation-resistant, self-compacting concrete.

[0016] This invention provides the application of the high-strength anti-segregation self-compacting concrete described in the above technical solution or the high-strength anti-segregation self-compacting concrete described in the above technical solution in the construction of secondary lining of tunnels. The high-strength anti-segregation self-compacting concrete is poured through the secondary lining trolley template. During the pouring, the vertical falling speed of the concrete slurry is <1.5m / s. After the pouring is completed, curing is carried out. The secondary lining trolley formwork includes a concrete pumping pipe; the end outlet of the concrete pumping pipe is connected to a 180° elbow, and an umbrella-shaped diversion cap is installed at the outlet of the elbow.

[0017] This invention provides a high-strength, anti-segregation self-compacting concrete. The raw materials for preparing this high-strength, anti-segregation self-compacting concrete, by weight, include: 230-280 parts cement, 60-85 parts fly ash microspheres, 30-55 parts mineral powder, 35-90 parts silica fume, 15-32 parts water glass, 1600-1800 parts aggregate, a viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, an expansion agent, composite fibers, and mixing water. The aggregate includes coarse aggregate and fine aggregate; the coarse aggregate has a particle size of 5-8 mm and 10-16 mm; the mass of the 5-8 mm coarse aggregate is 65-75% of the total mass of the coarse aggregate; the fineness modulus of the fine aggregate is 2.6-3.0; the mass of the fine aggregate is 40-42% of the total mass of the aggregate; the viscosity-reducing polycarboxylate superplasticizer is... The amount of the composite fiber is 1.6-1.9% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; the cationic viscosity modifier is 0.1-0.13% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; the cationic charge density of the cationic viscosity modifier is 0.4-0.7 meq / g; the expansive agent is 8-10% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; the amount of the composite fiber is 0.2-0.5% of the total volume of the high-strength anti-segregation self-compacting concrete; the composite fiber includes steel fiber and polymer fiber; the volume ratio of the steel fiber and polymer fiber is (0.5-2):1; the shape of the composite fiber is one or more of wavy, segmented, and spiral; the water-cement ratio of the high-strength anti-segregation self-compacting concrete is 0.22-0.23. The high-strength, anti-segregation self-compacting concrete provided by this invention utilizes steel fibers to form a uniform three-dimensional metal skeleton. Due to its high density, the steel fibers drive the surrounding slurry to move synchronously during flow, preventing aggregate settling. The polymer fibers have a low density and tend to be distributed in the upper slurry. At the same time, the spiral, segmented, or wavy structures on the surfaces of the steel and polymer fibers increase the mechanical interlocking force between the fibers and the slurry, forming a "buoyancy anchor" that effectively resists the sinking tendency of fibers and coarse aggregates, thus achieving "low viscosity and high anti-settling properties." The cationic viscosity modifier imparts excellent thixotropic properties to the concrete, effectively locking in aggregates and water to prevent segregation, achieving high flowability and high stability. Water glass can reduce the impact of hardening shrinkage on concrete performance, improve the crack resistance and durability of concrete, and enhance the compatibility of aggregates with other raw materials. The "discontinuous gradation" strategy can reduce the mechanical interlocking force of particles during mixing, causing the resistance of the concrete to drop sharply during flow, and then maintain uniformity through frictional self-locking when stationary, improving its stability. The results of the embodiments show that the high-strength anti-segregation self-compacting concrete provided by the present invention has an initial spread ≥680mm, T500≤3s, segregation rate ≤3% with a 5m drop, 28d compressive strength ≥140MPa, 56d restricted expansion rate ≥0.03%, 56d drying shrinkage rate ≤0.02%, filling density ≥98%, no through voids, and micro-bubble rate <1.0%. Detailed Implementation

[0018] This invention provides a high-strength, anti-segregation, self-compacting concrete. The raw materials for preparing the high-strength, anti-segregation, self-compacting concrete, by weight, include: 230-280 parts of cement, 60-85 parts of fly ash microspheres, 30-55 parts of mineral powder, 35-90 parts of silica fume, 15-32 parts of water glass, 1600-1800 parts of aggregate, a viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, an expansion agent, composite fibers, and mixing water. The aggregate includes coarse aggregate and fine aggregate; the coarse aggregate has a particle size of 5-8 mm and 10-16 mm; the mass of the coarse aggregate with a particle size of 5-8 mm accounts for 65-75% of the total mass of the coarse aggregate; the fineness modulus of the fine aggregate is 2.6-3.0; the mass of the fine aggregate accounts for 40-42% of the total mass of the aggregate. The dosage of the viscosity-reducing polycarboxylate superplasticizer is 1.6-1.9% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. The cationic viscosity modifier comprises 0.1-0.13% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; the cationic charge density of the cationic viscosity modifier is 0.4-0.7 meq / g. The expansion agent comprises 8-10% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. The amount of composite fiber used is 0.2~0.5% of the total volume of high-strength anti-segregation self-compacting concrete; the composite fiber includes steel fiber and polymer fiber; the volume ratio of steel fiber to polymer fiber is (0.5~2):1; the shape of the composite fiber is one or more of the following: wavy, segmented structure and spiral. The water-cement ratio of the high-strength anti-segregation self-compacting concrete is 0.22~0.23.

[0019] The raw materials for preparing the high-strength, anti-segregation, self-compacting concrete of the present invention, by weight, include 230-280 parts of cement; the cement is preferably silicate cement, more preferably P·O 52.5 cement. As one embodiment of the present invention, the weight of the cement can be 235 parts, 240 parts, 245 parts, 250 parts, 255 parts, 260 parts, 265 parts, 270 parts, or 275 parts. In the present invention, the cement, as the main gelling material, undergoes a hydration reaction with water to generate cementitious substances such as calcium silicate hydrate (CSH). These substances, like glue, coat and fill the surface and gaps of the aggregate, firmly bonding the aggregate together through physical interlocking and chemical bonding forces to form a dense artificial stone.

[0020] The raw materials for preparing the high-strength, anti-segregation, self-compacting concrete of the present invention, based on 230-280 parts by weight of cement, include 60-85 parts of fly ash microspheres; the fly ash microspheres are preferably Grade I fly ash microspheres with a water requirement ratio ≤92%; the particle size D50 of the fly ash microspheres is preferably 1.5-2.5 μm; the alumina and silica content in the fly ash microspheres is preferably ≥80%; using cement as an activity index, the 7-day activity of the fly ash microspheres is preferably ≥80%, and the 28-day activity is preferably ≥105%. In one embodiment of the present invention, the mass fraction of the fly ash microspheres can be 65, 70, 75, or 80 parts. In this invention, the ultrafine fly ash utilizes its spherical effect to offset the high viscosity caused by the ultra-low water-cement ratio (<0.25), enabling the concrete to achieve the required flowability for self-compacting, and its lower early activity helps control the heat of hydration.

[0021] The raw materials for preparing the high-strength, anti-segregation, self-compacting concrete of the present invention, based on 230-280 parts by weight of cement, include 30-55 parts of mineral powder; the specific surface area of ​​the mineral powder is preferably ≥800 m². 2 / kg; using cement as an activity index, the 7-day activity of the mineral powder is preferably ≥100%, and the 28-day activity is preferably ≥115%. In one embodiment of the invention, the mass fraction of the mineral powder can be 35 parts, 40 parts, 45 parts, or 50 parts. In this invention, the high activity of the mineral powder is key to ensuring the excess strength of concrete in its later stages. Cement hydration produces calcium hydroxide, which the mineral powder immediately reacts to generate more CSH, making the paste denser, stronger, and more chemically stable, without affecting cationic viscosity modifiers, etc. Simultaneously, the irregular shape of the mineral powder increases the cohesion of the concrete paste, effectively "locking in" high-density steel fibers and coarse aggregates, compensating for the segregation risk caused by fly ash microspheres.

[0022] The raw materials for preparing the high-strength, segregation-resistant, self-compacting concrete of the present invention, based on 230-280 parts by weight of cement, include 35-90 parts of silica fume; the average particle size of the silica fume is preferably 0.1-0.3 μm, more preferably 0.15-0.25 μm; the silica content in the silica fume is preferably 85-97% by weight. As one embodiment of the present invention, the mass fraction of the silica fume can be 40, 45, 50, 55, 60, 65, 70, 75, 80, or 85 parts. In this invention, silica fume significantly reduces porosity through the micro-aggregate filling effect, making the concrete extremely dense and thus achieving ultra-high strength. It can also release free water, increase the fluidity of the paste, and help improve its self-compacting properties. Silica fume has an extremely high SiO2 content (>85%) and is in an amorphous form, exhibiting extremely high chemical activity and a highly active pozzolanic effect. Calcium hydroxide produced during cement hydration contributes little to strength and is easily corroded; silica fume reacts rapidly with it to generate high-strength CSH gel (also a cementing substance, but stronger and denser), efficiently consuming calcium hydroxide. This reaction is most significant in the interfacial transition zone (ITZ) between aggregate and paste, significantly improving interfacial bonding and thus increasing the compressive and flexural strength of the concrete. The huge specific surface area of ​​silica fume adsorbs some free water, moderately increasing the cohesion of the paste and increasing its "thixotropy," which is extremely beneficial for resisting segregation and bleeding. At the same time, the spherical shape of silica fume, in conjunction with water-reducing agents, can still play a lubricating role, preventing loss of fluidity due to increased viscosity.

[0023] The raw materials for preparing the high-strength, anti-segregation self-compacting concrete of this invention, based on 230-280 parts by weight of cement, include 15-32 parts of water glass. In this invention, the modulus of the water glass is preferably 2.5-2.8. In this invention, water glass exhibits low shrinkage after hardening, reducing the accumulation of internal stress in the concrete and minimizing the impact of hardening shrinkage on concrete performance, thereby improving the crack resistance and durability of the concrete. Simultaneously, the water glass reacts with carbon dioxide in the air to precipitate silica gel, which has high bonding strength. This silica gel coats the aggregate to enhance its compatibility with other raw materials. After hardening, the silica gel exhibits high compressive strength, further improving the mechanical properties of the concrete.

[0024] The raw materials for preparing the high-strength, anti-segregation, self-compacting concrete of the present invention, based on 230-280 parts by weight of cement, include 1600-1800 parts of aggregate, preferably 1620-1780 parts, more preferably 1650-1750 parts, and even more preferably 1700 parts. In this invention, the aggregate includes coarse aggregate and fine aggregate; the coarse aggregate has a particle size of 5-8 mm and 10-16 mm; the mass of the coarse aggregate with a particle size of 5-8 mm is 65-75% of the total mass of the coarse aggregate, preferably 65-70%; the fineness modulus of the fine aggregate is 2.6-3.0; the mass of the fine aggregate is preferably 40-42% of the total mass of the aggregate, more preferably 40-41%. In this invention, coarse aggregate mainly provides skeleton stiffness and interlocking force, thereby improving the strength and elastic modulus of concrete. Fine aggregate is used to fill the voids in coarse aggregate, improve the bond between the paste and coarse aggregate, and regulate fluidity. The "discontinuous gradation" strategy can reduce the mechanical interlocking force of particles during mixing, so that the resistance of concrete drops sharply when flowing, and then maintains uniformity through frictional self-locking when stationary, thereby improving its stability.

[0025] In one embodiment of the present invention, the coarse aggregate can be crushed granite; the crushing index of the coarse aggregate is ≤8%; the fine aggregate is preferably manufactured sand; and the mud content of the fine aggregate is preferably ≤1.0%.

[0026] In this invention, the dosage of the viscosity-reducing polycarboxylate superplasticizer is 1.6-1.9% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume, preferably 1.7-1.8%; the water reduction rate of the viscosity-reducing polycarboxylate superplasticizer is preferably ≥35%. This invention, by adding the viscosity-reducing polycarboxylate superplasticizer, can significantly reduce the yield stress of concrete and provide high initial fluidity.

[0027] This invention does not specifically limit the source of the viscosity-reducing polycarboxylate superplasticizer; any commercially available viscosity-reducing polycarboxylate superplasticizer well-known to those skilled in the art can be used. In the embodiments of this invention, the viscosity-reducing polycarboxylate superplasticizer can be CSP-17 produced by Guangdong Hongqiang New Materials Co., Ltd.

[0028] In this invention, the cationic viscosity modifier comprises 0.1-0.13% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume, preferably 0.11-0.12%; the cationic charge density of the cationic viscosity modifier is 0.4-0.7 meq / g, preferably 0.5-0.6 meq / g. In this invention, the cationic viscosity modifier adsorbs negatively charged cement and silica fume particles through cationic groups, forming a reversible, dynamic, flexible network structure between the particles. This network is temporarily disrupted under high shear (pumping, flow), resulting in a decrease in viscosity; it is rapidly rebuilt under low shear or static conditions (free fall, cessation of flow), providing "dynamic viscosity" and imparting excellent thixotropic properties to the concrete. This effectively locks in aggregates and moisture, preventing segregation and ensuring that the concrete can quickly "stand firm" after flowing to the arch, without flowing or segregating, and can fill well under pressure, achieving high flowability and high stability.

[0029] This invention does not specifically limit the source of the cationic viscosity modifier; any commercially available cationic viscosity modifier well-known to those skilled in the art can be used. In the embodiments of this invention, the cationic viscosity modifier may be XY-T007 produced by Shandong Xianyuan Chemical Technology Co., Ltd. or TC-VMA100 produced by Zhenjiang Tongchuang New Materials Technology Co., Ltd.

[0030] In this invention, the expansive agent comprises 8-10% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume, preferably 8.5-9.5%, and more preferably 9%. In this invention, the expansive agent generates moderate volume expansion through its own chemical reaction, compensating for the shrinkage of concrete, thereby reducing or preventing cracking.

[0031] In this invention, the expanding agent is preferably a calcium-magnesium composite expanding agent; the calcium-magnesium composite expanding agent is preferably a composite of magnesium oxide expanding agent and calcium sulfoaluminate-calcium oxide expanding agent; the mass content of the magnesium oxide expanding agent in the calcium-magnesium composite expanding agent is preferably 20-35%. As one embodiment of this invention, the mass content of the magnesium oxide expanding agent in the calcium-magnesium composite expanding agent can be 21%, 22%, 23%, 24%, 25%, 26%, 27%, 28%, 29%, 30%, 31%, 32%, 33%, or 34%. In this invention, the calcium-magnesium composite expansive agent is mainly composed of calcium sulfoaluminate-calcium oxide expansive agent and supplemented by magnesium oxide expansive agent. The calcium oxide in the calcium sulfoaluminate-calcium oxide expansive agent has a fast hydration reaction and mainly provides early expansion for 1 to 7 days, generating calcium hydroxide (CH), which is the main source of early expansion. Calcium sulfoaluminate (CSA) reacts with gypsum to generate ettringite (AFt), providing mid-term expansion for 7 to 28 days. The magnesium oxide expansive agent has relatively low hydration activity and mainly provides late-term expansion after 28 days, generating magnesium hydroxide (MH). This can effectively compensate for the drying shrinkage and cooling shrinkage in the later stage of concrete hardening, achieving dual compensation in the early stage (hydration temperature rise stage) and the later stage (cooling shrinkage stage).

[0032] In this invention, the magnesium oxide expansive agent preferably contains ≥85% magnesium oxide by mass; the free calcium oxide (f-CaO) content in the magnesium oxide expansive agent is preferably ≤2.0% by mass; and the loss on ignition of the magnesium oxide expansive agent is preferably ≤4.0%. In this invention, the anhydrous calcium sulfoaluminate (CSA) content in the calcium sulfoaluminate-calcium oxide expansive agent is preferably 40-60% by mass; the calcium sulfate content in the calcium sulfoaluminate-calcium oxide expansive agent is preferably 20-40% by mass; the free calcium oxide (f-CaO) content in the calcium sulfoaluminate-calcium oxide expansive agent is preferably 10-25% by mass; and the impurity content in the calcium sulfoaluminate-calcium oxide expansive agent is preferably ≤5% by mass. This invention does not impose any special limitations on the specific sources of the magnesium oxide expansive agent and the calcium sulfoaluminate-calcium oxide expansive agent; commercially available products well-known to those skilled in the art can be used. This invention further improves the crack resistance of concrete by controlling the composition of the magnesium oxide expansive agent and the calcium sulfoaluminate-calcium oxide expansive agent.

[0033] In this invention, the amount of composite fiber is 0.2-0.5% of the total volume of high-strength anti-segregation self-compacting concrete; the composite fiber includes steel fiber and polymer fiber; the volume ratio of steel fiber to polymer fiber is (0.5-2):1; the shape of the composite fiber is one or more of wavy, segmented, and spiral; the segmented structure is preferably formed by embossing; the parameters of the spiral shape preferably include: spiral diameter 2-4 mm, spiral pitch 6-12 mm, and spiral turns 1.5-5. In one embodiment of the present invention, the amount of composite fiber can be 0.25%, 0.3%, 0.35%, 0.4% or 0.45% of the total volume of high-strength anti-segregation self-compacting concrete; the volume ratio of steel fiber to polymer fiber can be 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1:1, 1.1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1 or 1.8:1. In this invention, steel fibers can form a uniform three-dimensional metal skeleton in the slurry. Due to their high density, they drive the surrounding slurry to move synchronously during flow, preventing aggregate settling. Polymer fibers have a low density and tend to be distributed in the upper part of the slurry. At the same time, the spiral, segmented, or wavy structures on the surfaces of steel and polymer fibers increase the mechanical interlocking force between the fibers and the slurry, forming a "buoyancy anchor" that effectively resists the sinking tendency of fibers and coarse aggregates, thereby achieving "low viscosity and high anti-sinking". Meanwhile, the uneven surface of the wavy fibers increases the contact area and frictional resistance with the cement matrix, while the segmented structure provides a "locking effect" to prevent the fibers from being pulled out of the concrete.

[0034] In embodiments of the present invention, the length of the steel fiber can be 10-15 mm; the aspect ratio of the steel fiber can be 60-70; the material of the polymer fiber can be polypropylene or polyethylene; the length of the polymer fiber can be 25-60 mm; and the diameter of the polymer fiber can be 0.5-1.2 mm.

[0035] In this invention, the mixing water is preferably purified water or drinking water. This invention does not impose a specific limit on the amount of mixing water used, as long as the water-cement ratio of the high-strength, anti-segregation self-compacting concrete meets the requirements. In this invention, the water-cement ratio of the high-strength, anti-segregation self-compacting concrete is 0.22~0.23. By using a lower water-cement ratio, this invention ensures good fluidity after mixing while avoiding problems such as flow and segregation caused by excessive water addition.

[0036] In this invention, steel fibers can form a uniform three-dimensional metal skeleton in the slurry. Due to their high density, they drive the surrounding slurry to move synchronously during flow, preventing aggregate settling. Polymer fibers have a low density and tend to be distributed in the upper part of the slurry. At the same time, the spiral, segmented, or wavy structures on the surfaces of steel and polymer fibers increase the mechanical interlocking force between the fibers and the slurry, forming a "buoyancy anchor" that effectively resists the sinking tendency of fibers and coarse aggregates, thereby achieving "low viscosity and high anti-settling". The cationic viscosity modifier gives the concrete excellent thixotropic properties, thereby effectively locking in aggregates and water, preventing segregation, and achieving high flowability and high stability. Water glass can reduce the impact of hardening shrinkage on concrete performance, improve the crack resistance and durability of concrete, and at the same time, water glass enhances the compatibility of aggregates with other raw materials. The "discontinuous gradation" strategy can reduce the mechanical interlocking force of particles during mixing, causing the resistance of concrete to drop sharply during flow, and then maintain uniformity through frictional self-locking when stationary, improving its stability.

[0037] This invention also provides a method for preparing the high-strength, segregation-resistant, self-compacting concrete described in the above technical solution, comprising the following steps: Cement, fly ash microspheres, mineral powder, silica fume, composite fiber and expansion agent are mixed and then dry-mixed to obtain dry-mixed material; A viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, and a portion of mixing water are premixed to obtain an additive solution. The additive solution and the dry mixture are wet-mixed to obtain a slurry; Aggregates are added to the slurry, followed by water glass and the remaining mixing water, to obtain high-strength, segregation-resistant, self-compacting concrete.

[0038] This invention does not impose specific limitations on the stirring rate and dry mixing time of the dry mix. Based on the technical knowledge of those skilled in the art, the goal is simply to ensure that all components are mixed evenly. In embodiments of this invention, the dry mixing time can be 1-2 minutes.

[0039] In this invention, the mixing water is preferably 80-90% of the total mixing water. This invention avoids excessively high local concentrations when the water-reducing agent and viscosity modifier are mixed by mixing the viscosity-reducing polycarboxylate superplasticizer, the cationic viscosity modifier, and the mixing water into an additive solution, and then adding it.

[0040] The present invention does not impose any special limitations on the specific operation of the premixing, as long as it can be mixed evenly.

[0041] This invention does not impose specific limitations on the stirring rate and dry mixing time for the wet mixing. Based on the technical knowledge of those skilled in the art, the goal is simply to ensure that all components are mixed uniformly. In embodiments of this invention, the wet mixing time can be 2-3 minutes.

[0042] In this invention, the aggregate is preferably added under stirring conditions. This invention does not impose any special limitations on the stirring rate and time, which can be determined based on the technical common sense of those skilled in the art.

[0043] In this invention, the preferred method for adding the water glass and the remaining mixing water is to first mix the water glass and the remaining mixing water to form a mixture, and then add the mixture. In this invention, the mixture is preferably added within 30-90 seconds. By controlling the addition time of the mixture, this invention allows for slow addition, preventing excessively rapid local reactions that could lead to "flash coagulation" or clumping of the mixture.

[0044] In this invention, it is preferable to rapidly stir for 1-2 minutes after adding water glass and the remaining mixing water. This invention does not have a specific limitation on the exact stirring speed, as long as it ensures rapid and uniform mixing. This rapid stirring method prevents rapid hardening from affecting subsequent pouring.

[0045] The present invention also provides the application of the high-strength anti-segregation self-compacting concrete described in the above technical solution or the high-strength anti-segregation self-compacting concrete described in the above technical solution in the construction of secondary lining of tunnel. The high-strength anti-segregation self-compacting concrete is poured through the secondary lining trolley template. During the pouring, the vertical falling speed of the concrete slurry is <1.5m / s. After the pouring is completed, curing is carried out. The secondary lining trolley formwork includes a concrete pumping pipe; the end outlet of the concrete pumping pipe is connected to a 180° elbow, and an umbrella-shaped diversion cap is installed at the outlet of the elbow.

[0046] This invention, by setting a 180° elbow at the end outlet of the concrete pumping pipeline and installing an umbrella-shaped diversion cap, can reduce the vertical falling speed of the concrete slurry after discharge to less than 1.5 m / s.

[0047] In this invention, the pumping velocity during casting is preferably 8-12 m / s. 3 / h; the preferred pumping pressure during pouring is 2~4MPa. By controlling the pumping flow rate and pressure, this invention can ensure that the pouring interruption time does not exceed 30s, improve pouring efficiency, and avoid pouring voids.

[0048] This invention preferably incorporates intelligent curing monitoring during the pouring process; when the internal temperature of the poured concrete exceeds 35℃ or the tensile strain exceeds 150με, grouting compensation is performed on the area exceeding 35℃ or the tensile strain exceeds 150με. In this invention, the compensating agent used for grouting compensation preferably comprises 10-15% calcium sulfoaluminate-based expanding agent, 5-8% silica fume, and the balance being water; the average particle size of the silica fume is preferably 0.1-0.3μm, more preferably 0.15-0.25μm; the silica content in the silica fume is preferably 85-97% by mass; and the grouting pressure for grouting compensation is preferably 0.2-0.4MPa.

[0049] In this invention, the preferred curing method is steam curing or spray curing; the curing time in the mold is preferably ≥3 days. This invention does not impose any special limitations on the specific operation of steam curing and spray curing; selection can be made based on the technical knowledge of those skilled in the art. By adopting the above-mentioned curing methods and performing in-mold curing in the early stages, this invention can effectively control early cracking.

[0050] When the high-strength anti-segregation self-compacting concrete provided by this invention is used in the secondary lining construction of tunnels, by setting a 180° elbow at the end outlet of the concrete pumping pipeline and installing an umbrella-shaped diversion cap, the vertical falling speed of the concrete slurry after discharge can be less than 1.5m / s. This can not only avoid the concrete segregation caused by excessive falling speed during concrete pouring, but also prevent the concrete slurry from splashing, reduce internal voids, and achieve self-compacting of the concrete without vibration.

[0051] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0052] Example 1 A high-strength, anti-segregation self-compacting concrete, the raw materials for preparing the high-strength, anti-segregation self-compacting concrete by weight are: 253 parts cement, 77 parts fly ash microspheres, 42 parts mineral powder, 38 parts silica fume, 23 parts water glass, 1750 parts aggregate, viscosity-reducing polycarboxylate superplasticizer, cationic viscosity modifier, expansion agent, composite fiber and mixing water; The cement is P·O 52.5 cement; The fly ash microspheres are Class I fly ash microspheres with a water requirement ratio ≤92%; the particle size D50 of the fly ash microspheres is 1.5~2.5μm; the alumina and silica content of the fly ash microspheres is ≥80%; using cement as an activity index, the 7-day activity of the fly ash microspheres is ≥80%, and the 28-day activity is ≥105%; The specific surface area of ​​the mineral powder is ≥800m². 2 / kg; using cement as an activity index, the 7-day activity of the mineral powder is ≥100%, and the 28-day activity is ≥115%; The average particle size of the silica fume is 0.2 μm; the mass content of silica in the silica fume is 85-97%. The modulus of the water glass is 2.6; The aggregate consists of coarse aggregate and fine aggregate; the coarse aggregate has a particle size of 5-8 mm and 10-16 mm; the mass of the coarse aggregate with a particle size of 5-8 mm accounts for 70% of the total mass of the coarse aggregate; the fineness modulus of the fine aggregate is 2.8; the mass of the fine aggregate accounts for 41% of the total mass of the aggregate. The coarse aggregate is crushed granite; the crushing index of the coarse aggregate is ≤8%; the fine aggregate is manufactured sand; the mud content of the fine aggregate is ≤1.0%. The dosage of the viscosity-reducing polycarboxylate superplasticizer is 1.7% of the total mass of cement, fly ash microspheres, mineral powder and silica fume; the water reduction rate of the viscosity-reducing polycarboxylate superplasticizer is ≥35%; the viscosity-reducing polycarboxylate superplasticizer is CSP-17 produced by Guangdong Hongqiang New Materials Co., Ltd. The cationic viscosity modifier is 0.1% of the total mass of cement, fly ash microspheres, mineral powder and silica fume; the cationic charge density of the cationic viscosity modifier is 0.6 meq / g; and the cationic viscosity modifier is XY-T007 produced by Shandong Xianyuan Chemical Technology Co., Ltd. The expansion agent comprises 9% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; The expanding agent is a calcium-magnesium composite expanding agent; the calcium-magnesium composite expanding agent is a composite of magnesium oxide expanding agent and calcium sulfoaluminate-calcium oxide expanding agent; the mass content of magnesium oxide expanding agent in the calcium-magnesium composite expanding agent is 30%; the mass content of magnesium oxide in the magnesium oxide expanding agent is ≥85%; the mass content of free calcium oxide (f-CaO) in the magnesium oxide expanding agent is ≤2.0%; the loss on ignition of the magnesium oxide expanding agent is 2.0%; the mass content of anhydrous calcium sulfoaluminate (CSA) in the calcium sulfoaluminate-calcium oxide expanding agent is 55%; the mass content of calcium sulfate in the calcium sulfoaluminate-calcium oxide expanding agent is 30%; the mass content of free calcium oxide (f-CaO) in the calcium sulfoaluminate-calcium oxide expanding agent is 15%; the mass content of impurities in the calcium sulfoaluminate-calcium oxide expanding agent is ≤5%. The composite fiber is used at 0.4% of the total volume of the high-strength, anti-segregation self-compacting concrete; the composite fiber is composed of steel fiber and polymer fiber; the volume ratio of the steel fiber to the polymer fiber is 1:1; the length of the steel fiber is 10-15 mm; the aspect ratio of the steel fiber is 60-70; the polymer fiber is made of polypropylene; the length of the polymer fiber is 25-60 mm; the diameter of the polymer fiber is 0.5-1.2 mm; the shape of the composite fiber is helical; the parameters of the helical shape are: helix diameter 3 mm, helix pitch 8 mm, and 3 helix turns. The mixing water is drinking water, and the water-cement ratio of the high-strength anti-segregation self-compacting concrete is 0.22; The preparation method of the high-strength anti-segregation self-compacting concrete is as follows: Cement, fly ash microspheres, mineral powder, silica fume, composite fiber and expansion agent are mixed and then dry-mixed to obtain dry-mixed material; A viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, and a portion of the mixing water (80% of the total volume of the mixing water) are premixed to obtain an additive solution. The additive solution and the dry mixture are wet-mixed to obtain a slurry; Add aggregate to the slurry, mix water glass and remaining mixing water to obtain a mixture, then slowly add it over 60 seconds, and finally stir rapidly for 2 minutes to obtain high-strength anti-segregation self-compacting concrete.

[0053] Application Example 1 The high-strength anti-segregation self-compacting concrete, which was rapidly and evenly mixed in Example 1, was poured through a secondary lining trolley template. The vertical falling speed of the concrete slurry during pouring was <1.5m / s. Curing was carried out after pouring was completed. The secondary lining trolley formwork includes a concrete pumping pipeline; the end outlet of the concrete pumping pipeline is connected to a 180° elbow, and an umbrella-shaped diversion cap is installed at the outlet of the elbow. In this invention, the pumping velocity during casting is 10 m / s. 3 / h; The pumping pressure during the pouring process is 3MPa; Intelligent maintenance monitoring is implemented during the pouring process; The curing method is spray curing. During spray curing, spray once every 2 hours during the day, and spray at least 5 times to ensure that the environment is kept moist. The curing time in the mold is 3 days, and after 3 days, the mold is removed and curing continues for 28 days.

[0054] Example 2 The cationic viscosity modifier is 0.11% of the total mass of cement, fly ash microspheres, mineral powder and silica fume, and other conditions are the same as in Example 1.

[0055] Application Example 2 The method of using the high-strength anti-segregation self-compacting concrete in the secondary lining construction of tunnels described in Example 2 is the same as that in Application Example 1, except that other conditions are the same.

[0056] Example 3 The cationic viscosity modifier is 0.12% of the total mass of cement, fly ash microspheres, mineral powder and silica fume, and other conditions are the same as in Example 1.

[0057] Application Example 3 The method of using the high-strength anti-segregation self-compacting concrete in the secondary lining construction of tunnels described in Example 3 is the same as that in Application Example 1, except that other conditions are the same.

[0058] Comparative Example 1 The cationic viscosity modifier in Example 1 was replaced with a cellulose ether, and all other conditions were the same as in Example 1.

[0059] Comparative Application Example 1 The method of using concrete in the secondary lining construction of tunnels provided in Comparative Example 1 replaces the cationic viscosity modifier with cellulose ether, and other conditions are the same as in Application Example 1.

[0060] Comparative Example 2 The cationic viscosity modifier in Example 1 is omitted, and other conditions are the same as in Example 1.

[0061] Comparative Application Example 2 The method of using concrete in the secondary lining construction of tunnels provided in Comparative Example 2 omits the operation of including cationic viscosity modifier, and other conditions are the same as in Application Example 1.

[0062] Comparative Example 3 The cationic viscosity modifier is 0.0% of the total mass of cement, fly ash microspheres, mineral powder and silica fume, and other conditions are the same as in Example 1.

[0063] Comparative Application Example 3 The method of using concrete in the secondary lining construction of tunnels provided in Comparative Example 3 is the same as that in Application Example 1, except that other conditions are the same.

[0064] The performance of concrete provided in corresponding use cases 1-3 and comparative application examples 1-3 was tested, and the results are shown in Tables 1 and 2: Table 1 shows the performance of concrete provided in Application Examples 1-3 and Comparative Application Examples 1-3.

[0065] In Table 1, the initial expansion was determined according to the national standard "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T50080-2016); The T500 test was conducted according to the national standard "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T 50080). The height difference of the J ring is determined according to the national standards "Standard for Test Methods of Performance of Ordinary Concrete Mixtures" (GB / T50080) and "Technical Specification for Application of Self-Compacting Concrete" (JGJ / T 283). The segregation rate of a 5m drop was determined by a sieve analysis test based on the national standard "Technical Specification for Application of Self-Compacting Concrete" (JGJ / T 283-2012).

[0066] Table 2 shows the performance of concrete provided in Application Examples 1-3 and Comparative Application Examples 1-3.

[0067] In Table 2, the 28-day compressive strength was determined according to the national standard "Standard for Test Methods of Physical and Mechanical Properties of Concrete" (GB / T50081). The 56-day drying shrinkage rate was determined according to the national standard "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T 50082). The impermeability grade is determined according to the national standard "Standard for Test Methods of Long-Term Performance and Durability of Ordinary Concrete" (GB / T50082-2009).

[0068] As can be seen from Tables 1 and 2, the high-strength, anti-segregation self-compacting concrete provided in Example 1 of this invention meets the requirements of C140, high fluidity, high anti-segregation, and shrinkage compensation when used in tunnel secondary lining construction. Furthermore, the concrete performance is optimal when the cationic viscosity modifier is 0.11% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. However, when the cationic viscosity modifier is omitted, reduced, or replaced with other viscosity modifiers, the concrete's fluidity significantly decreases, the passage of reinforcing bars is poor, severe segregation occurs with high drops, the risk of pipe blockage is high, large areas of voids appear in the arch, and the strength fails to meet standards. This indicates that the cationic viscosity modifier is the best for improving the performance of concrete.

[0069] The filling density of concrete was detected by CT scanning and cross-sectional observation. Application Example 1 showed a filling density of 98.2%, with no through-cell voids and a microbubble rate of <1.0%; Application Example 2 showed a filling density of 99.1%, with no through-cell voids and a microbubble rate of <1.0%; Application Example 3 showed a filling density of 99.0%, with no through-cell voids and a microbubble rate of <1.0%. In contrast, Application Example 1 showed a filling density of 95.3%, with a relatively large number of microbubbles and a small number of through-cell voids; Application Example 2 showed a filling density of 93.6%, with a relatively large number of microbubbles and a small number of through-cell voids; and Application Example 3 showed a filling density of 94.1%, with a relatively large number of microbubbles and a small number of through-cell voids. This demonstrates that the addition of a cationic viscosity modifier can improve the filling density of concrete and exhibit excellent self-compacting properties.

[0070] Example 4 The amount of composite fiber used is 0.2% of the total volume of the high-strength anti-segregation self-compacting concrete, and other conditions are the same as in Example 1.

[0071] Application Example 4 The method of using the high-strength anti-segregation self-compacting concrete in the secondary lining construction of tunnels described in Example 4 is the same as that in Application Example 1, except that other conditions are the same.

[0072] Example 5 The amount of composite fiber used is 0.3% of the total volume of the high-strength anti-segregation self-compacting concrete, and other conditions are the same as in Example 1.

[0073] Application Example 5 The method of using the high-strength anti-segregation self-compacting concrete described in Example 5 in the secondary lining construction of tunnels is the same as that in Application Example 1, except that other conditions are the same.

[0074] Comparative Example 4 The composite fiber is omitted, and other conditions are the same as in Example 1.

[0075] Comparative Application Example 4 Compared with the method of using concrete in the secondary lining construction of tunnel described in Application Example 4, the relevant operations of composite fibers are omitted, and other conditions are the same as in Application Example 1.

[0076] Comparative Example 5 The composite fibers are replaced with steel fibers. The length of the steel fibers is 10-15 mm, the aspect ratio of the steel fibers is 60-70, and the surface of the steel fibers is free of spirals. Other conditions are the same as in Example 1.

[0077] Comparative Application Example 5 Compared with the method of using concrete in the secondary lining construction of tunnel described in Application Example 5, the relevant operations of composite fiber are replaced with steel fiber, and other conditions are the same as in Application Example 1.

[0078] The performance of concrete provided in corresponding use cases 4-5 and comparative application examples 4-5 was tested, and the results are shown in Tables 3 and 4: Table 3 shows the concrete performance provided in Application Examples 4-5 and Comparative Application Examples 4-5.

[0079] Table 4 shows the concrete performance provided in Application Examples 4-5 and Comparative Application Examples 4-5.

[0080] As can be seen from Tables 3 and 4, the high-strength anti-segregation self-compacting concrete provided in Examples 4-5 of the present invention meets the requirements of C140, high fluidity, high anti-segregation, and shrinkage compensation when used in secondary tunnel lining construction. However, when the type of fiber in the concrete is changed or the fiber is omitted, the fluidity of the concrete decreases significantly, severe segregation occurs at high drops, and the strength does not meet the standards. This indicates that the present invention, by using composite fibers, is beneficial to improving the mechanical properties of concrete and reducing segregation.

[0081] Comparative Example 6 Omit the water glass, and keep other conditions the same as in Example 1.

[0082] Comparative Application Example 6 Compared with the method of using concrete in the secondary lining construction of tunnel described in Application Example 6, the relevant operations of water glass are omitted, and other conditions are the same as in Application Example 1.

[0083] Comparative Example 7 The aggregate consists of coarse aggregate and fine aggregate. The coarse aggregate is a continuously graded coarse aggregate with a particle size of 5-16 mm. The mass content of the 5-8 mm coarse aggregate is 20%, the mass content of the 8-12 mm coarse aggregate is 40%, the mass content of the 12-16 mm coarse aggregate is 40%, and the mass content of the fine aggregate is 41% of the total mass of the aggregate. Other conditions are the same as in Example 1.

[0084] Comparative Application Example 7 The method of using concrete in the secondary lining construction of tunnels described in Application Example 7 is the same as that in Application Example 1.

[0085] The performance of the concrete provided in comparative application examples 6 and 7 was tested, and the results are shown in Tables 5 and 6: Table 5 compares the performance of concrete provided in Application Examples 6-7.

[0086] Table 6 compares the performance of concrete provided in Application Examples 6-7.

[0087] As can be seen from Tables 5 and 6, although the initial spread and strength of concrete are not significantly affected when water glass is omitted, the segregation rate at a 5m drop increases slightly, and the drying shrinkage rate is significantly improved. This indicates that the present invention can reduce the segregation and shrinkage of concrete by adding water glass. When continuous gradation of coarse aggregate is adopted, the initial spread and strength of concrete are not significantly affected, but their segregation and shrinkage properties are also affected. This indicates that the present invention can significantly improve the segregation resistance and reduce the shrinkage of concrete by adding water glass and adjusting the aggregate gradation.

[0088] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A high-strength, segregation-resistant, self-compacting concrete, wherein the raw materials for preparing the high-strength, segregation-resistant, self-compacting concrete, by weight, include: 230-280 parts cement, 60-85 parts fly ash microspheres, 30-55 parts mineral powder, 35-90 parts silica fume, 15-32 parts water glass, 1600-1800 parts aggregate, viscosity-reducing polycarboxylate superplasticizer, cationic viscosity modifier, expansion agent, composite fiber and mixing water. The aggregate includes coarse aggregate and fine aggregate; the coarse aggregate has a particle size of 5-8 mm and 10-16 mm; the mass of the coarse aggregate with a particle size of 5-8 mm accounts for 65-75% of the total mass of the coarse aggregate; the fineness modulus of the fine aggregate is 2.6-3.0; the mass of the fine aggregate accounts for 40-42% of the total mass of the aggregate. The dosage of the viscosity-reducing polycarboxylate superplasticizer is 1.6-1.9% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. The cationic viscosity modifier comprises 0.1-0.13% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume; the cationic charge density of the cationic viscosity modifier is 0.4-0.7 meq / g. The expansion agent comprises 8-10% of the total mass of cement, fly ash microspheres, mineral powder, and silica fume. The amount of composite fiber used is 0.2~0.5% of the total volume of high-strength anti-segregation self-compacting concrete; the composite fiber includes steel fiber and polymer fiber; the volume ratio of steel fiber to polymer fiber is (0.5~2):1; the shape of the composite fiber is one or more of the following: wavy, segmented structure and spiral. The water-cement ratio of the high-strength anti-segregation self-compacting concrete is 0.22~0.

23.

2. The high-strength, segregation-resistant, self-compacting concrete according to claim 1, characterized in that, The fly ash microspheres are Class I fly ash microspheres with a water requirement ratio ≤ 92%; the particle size D50 of the fly ash microspheres is 1.5~2.5μm.

3. The high-strength, segregation-resistant, self-compacting concrete according to claim 1, characterized in that, The average particle size of the silica fume is 0.1~0.3μm; the mass content of silica in the silica fume is 85~97%.

4. The high-strength, segregation-resistant, self-compacting concrete according to claim 1, characterized in that, The steel fiber has a length of 10-15 mm and an aspect ratio of 60-70.

5. The high-strength, anti-segregation, self-compacting concrete according to claim 1, characterized in that, The polymer fiber is made of polypropylene or polyethylene; the length of the polymer fiber is 25~60mm; and the diameter of the polymer fiber is 0.5~1.2mm.

6. The high-strength, segregation-resistant, self-compacting concrete according to claim 1, characterized in that, The expanding agent is a magnesium oxide expanding agent and a calcium sulfoaluminate-calcium oxide expanding agent; the mass content of the magnesium oxide expanding agent in the expanding agent is 20~35%.

7. The high-strength, anti-segregation, self-compacting concrete according to claim 6, characterized in that, The magnesium oxide expanding agent contains ≥85% magnesium oxide by mass; the calcium sulfoaluminate-calcium oxide expanding agent contains 40-60% anhydrous calcium sulfoaluminate by mass; the calcium sulfoaluminate-calcium oxide expanding agent contains 20-40% calcium sulfate by mass; and the calcium sulfoaluminate-calcium oxide expanding agent contains 10-25% free calcium oxide by mass.

8. The high-strength, segregation-resistant, self-compacting concrete according to claim 1, characterized in that, The modulus of the water glass is 2.5 to 2.

8.

9. A method for preparing high-strength, segregation-resistant, self-compacting concrete according to any one of claims 1 to 8, comprising the following steps: Cement, fly ash microspheres, mineral powder, silica fume, composite fiber and expansion agent are mixed and then dry-mixed to obtain dry-mixed material; A viscosity-reducing polycarboxylate superplasticizer, a cationic viscosity modifier, and a portion of mixing water are premixed to obtain an additive solution. The additive solution and the dry mixture are wet-mixed to obtain a slurry; Aggregates are added to the slurry, followed by water glass and the remaining mixing water, to obtain high-strength, segregation-resistant, self-compacting concrete.

10. The application of the high-strength anti-segregation self-compacting concrete according to any one of claims 1 to 8 or the high-strength anti-segregation self-compacting concrete according to claim 9 in the secondary lining construction of tunnels, characterized in that, The high-strength anti-segregation self-compacting concrete is poured using a secondary lining trolley template. During pouring, the vertical falling speed of the concrete slurry is <1.5m / s. Curing is carried out after pouring is completed. The secondary lining trolley formwork includes a concrete pumping pipe; the end outlet of the concrete pumping pipe is connected to a 180° elbow, and an umbrella-shaped diversion cap is installed at the outlet of the elbow.

Images