Low-carbon repairing material for precast concrete component as well as preparation method and use method of low-carbon repairing material

Abstract

The invention belongs to the technical field of precast concrete component crack repairing and solid waste, and particularly relates to a precast concrete component low-carbon repairing material and a preparation method and a use method thereof. The low-carbon repairing material has good compressive strength, breaking strength and bonding strength, the 28-day dry shrinkage rate is low, and the initial setting time and the final setting time of the low-carbon repairing material are short. By adopting the low-carbon repairing material, not only can the compressive strength and breaking strength of the repaired concrete prefabricated component be improved, but also the repairing time of concrete cracks can be shortened, and the repairing efficiency of concrete can be improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of crack repair of concrete precast components and solid waste, and specifically relates to a low-carbon repair material for concrete precast components, a preparation method, and a usage method. Background Art

[0002] Concrete precast components are building components prefabricated in a factory with concrete as the basic material, including beams, slabs, columns, and building decoration accessories, etc.

[0003] At present, the phenomenon of cracking in domestic concrete precast components is relatively common. Most use cement-based high-strength repair materials. Such materials have a large amount of cement, large color difference, are not environmentally friendly, have poor bonding, and the repair process is cumbersome.

[0004] Application No.: 202411872221.8 discloses a rapid repair material for concrete based on microbial mineralization and its preparation method and application. Application No.: 202411552971.7 discloses a construction method for repairing cracks in the shotcrete surface layer. Application No. 202411790460.9 discloses a method for repairing concrete cracks that does not affect the observation of active cracks in the concrete structure. Application No.: 202411904251.2 discloses a construction method for the joints of precast sandwich insulation shear wall exterior wall panels. The repair materials and repair methods disclosed in the above related patent applications cannot solve the above problems.

[0005] Therefore, there is a need to provide a repair material and a repair process that can reduce the color difference, reduce carbon emissions, and improve the bonding strength between the repair material and concrete. Summary of the Invention

[0006] Based on the above technical background, the main purpose of the present invention is to provide a low-carbon repair material for concrete precast components, a preparation method, and a usage method to overcome the deficiencies in the prior art.

[0007] To achieve the foregoing invention purpose, the technical solutions adopted by the present invention include:

[0008] In the first aspect of the present invention, there is provided a low-carbon repair material for concrete precast components, and the low-carbon repair material for concrete precast components includes component A, component B, and component C.

[0009] Component A includes the following raw materials in parts by weight: 10 - 15 parts by weight of mineral powder, 1 - 4 parts by weight of industrial solid waste powder, 1 - 4 parts by weight of steel slag, 40 - 80 parts by weight of graded sand, and 2 - 6 parts by weight of high-strength fiber.

[0010] Preferably, the component A comprises raw materials in the following parts by weight: 12 parts by weight of mineral powder, 3 parts by weight of industrial solid waste powder, 3 parts by weight of steel slag, 60 parts by weight of graded sand, and 4 parts by weight of high-strength fiber.

[0011] Mineral powder is a high-fineness and high-activity powder obtained by processing water-quenched blast furnace slag through processes such as drying and grinding. It is an excellent concrete admixture and cement blending material. By using granulated blast furnace slag powder, the compressive strength of concrete can be effectively improved, and the cost of concrete can be reduced. At the same time, it can inhibit alkali-aggregate reaction, improve the compactness of concrete, and has a significant effect on improving impermeability and corrosion resistance.

[0012] Graded sand and gravel refers to a mixed material in which the particle sizes (granule sizes) of sand or gravel are mixed in a certain proportion. It can optimize the paste-aggregate ratio of concrete and improve its workability. The use of graded sand makes the concrete more compact, which is beneficial to improving the mechanical properties of concrete.

[0013] The component B comprises raw materials in the following parts by weight: 15 - 30 parts by weight of water glass, 1 - 4 parts by weight of sodium hydroxide, and 1 - 4 parts by weight of water.

[0014] Preferably, the component B comprises raw materials in the following parts by weight: 20 parts by weight of water glass, 2 parts by weight of sodium hydroxide, and 3 parts by weight of water.

[0015] Water glass: It is a water-soluble silicate and a mineral binder. Water glass has the advantages of strong adhesion, relatively high strength, good acid resistance, and good heat resistance.

[0016] The component C comprises raw materials in the following parts by weight: 2 - 4 parts by weight of limestone powder and 2 - 4 parts by weight of quartz powder.

[0017] Preferably, the component C comprises raw materials in the following parts by weight: 3 parts by weight of limestone powder and 3 parts by weight of quartz powder.

[0018] Limestone powder is industrial calcium carbonate. Lime and limestone are widely used as raw materials in building materials and industry. Limestone powder has low cost and excellent performance, and has good heat insulation performance. Adding an appropriate amount of limestone powder to the repair material can improve the concrete structure, enhance the workability and compactness of concrete, and improve the sulfate corrosion resistance of concrete at low temperatures.

[0019] Quartz powder (same as quartz sand) is also called silica powder. Quartz sand is a hard, wear-resistant, and chemically stable silicate mineral, with high melting point, high hardness, corrosion resistance, and excellent insulation performance. It has been found through experiments that adding an appropriate amount of quartz powder to the repair material helps to improve the corrosion resistance and compressive strength of concrete.

[0020] The particle sizes of the mineral powder, industrial solid waste powder, limestone powder, and quartz powder are all < 10 μm.

[0021] Preferably, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder are all < 5 μm.

[0022] The particle size of the graded sand is 0.3 - 1.25 mm. Preferably, the particle size of the graded sand is 0.5 - 1.0 mm.

[0023] The particle size of the steel slag is 5 - 30 mm.

[0024] Preferably, the particle size of the steel slag is 5 - 15 mm. The strength of the steel slag is related to its particle size. It has been found through experiments that when the particle size range of the steel slag is 5 - 15 mm, the strength of the steel slag is relatively high.

[0025] It has been found through experiments that the particle sizes of the mineral powder, industrial solid waste powder, limestone powder, quartz powder, graded sand and steel slag all affect the performance of the repair material. When the particle sizes of the mineral powder, industrial solid waste powder, limestone powder, quartz powder, graded sand and steel slag are within the above ranges, the obtained low-carbon repair material has higher compressive, flexural and bonding strengths, lower dry shrinkage rate, and shorter initial setting and final setting times.

[0026] The high-strength fiber is selected from one or more of carbon fiber, aramid fiber, basalt fiber, polyphenylene sulfide fiber, polyurethane fiber, and polyamide fiber.

[0027] Preferably, the high-strength fiber is a mixture of carbon fiber and aramid fiber.

[0028] More preferably, the mass ratio of the carbon fiber to the aramid fiber is (1 - 3):1.

[0029] Further preferably, the mass ratio of the carbon fiber to the aramid fiber is 2:1.

[0030] It has been found through experiments that when the carbon fiber and aramid fiber are mixed into the repair material in the above mass ratio, the "pores" in the repair material can be filled, which helps to improve the bonding performance and mechanical strength of the repair material.

[0031] The length of the high-strength fiber is 1 - 3 cm. Preferably, the length of the high-strength fiber is 2 cm.

[0032] The second aspect of the present invention lies in providing a preparation method of the low-carbon repair material described in the first aspect of the present invention, and the preparation method includes the following steps:

[0033] Mix the raw materials in component A evenly at a stirring speed of 2000 - 4000 rpm.

[0034] Preferably, mix the raw materials in component A evenly at a stirring speed of 3000 rpm.

[0035] Mix the raw materials in Component B evenly at a stirring speed of 1000 - 2000 rpm, and mix the raw materials in Component C evenly at a stirring speed of 1000 - 2000 rpm.

[0036] Preferably, mix the raw materials in Component B evenly at a stirring speed of 1500 rpm, and mix the raw materials in Component C evenly at a stirring speed of 1500 rpm.

[0037] Mix the evenly - mixed Component A, Component B, and Component C together evenly at a stirring speed of 2000 - 4000 rpm.

[0038] Preferably, mix the evenly - mixed Component A, Component B, and Component C together evenly at a stirring speed of 3000 rpm.

[0039] After each component is mixed evenly and then mixed together, it is beneficial to shorten the mixing time and improve the preparation efficiency of the low - carbon repair material.

[0040] The third aspect of the present invention lies in providing a method for using the low - carbon repair material described in the first aspect of the present invention. The method for use includes: measuring the crack width with a crack card, confirming the crack defects of the precast concrete member, as Figure 1 shown, and determining the corresponding repair method according to the crack defects.

[0041] The method for use includes the step of filling small cracks with the low - carbon repair material. Among them, the width of the small cracks is between 0.2 mm and 0.5 mm, and the depth is less than the protective layer.

[0042] Step a: Along the length direction of the small crack, cut a groove at each end of the small crack. Each groove has an angle of 40 - 45° and a depth of 15 - 20 mm, then open a V - shaped opening, and chisel out a closed area along the small crack at the V - shaped opening;

[0043] Step b: Grind the surface of the closed area to form a ground surface, clean the ground surface to make the ground surface smooth and clean, fill the epoxy - based liquid into the closed area, cure it in the shade naturally, and after the epoxy - based liquid solidifies, perform a finishing treatment on the repair surface with the low - carbon repair material;

[0044] Step c: After the low - carbon repair material solidifies, polish it with fine sandpaper to fade the boundary repair marks.

[0045] Preferably, the method for use further includes the step of filling large cracks with the low - carbon repair material. Among them, the large cracks are those with a crack width greater than 0.5 mm or a depth exceeding the protective layer. The method for use includes:

[0046] Step 1: Drill holes along the crack at intervals of about 20 - 40 cm, and then clean the crack.

[0047] Step 2: Place the injection tube into the drilled hole, seal the surface of the crack with the sealant. After the sealant hardens, inject the low - carbon repair material into the crack through the injection tube. After the low - carbon repair material hardens, remove the injection tube and polish the surface.

[0048] The beneficial effects of the present invention are as follows:

[0049] (1) The low - carbon repair material of the present invention uses solid waste materials as the main raw materials and adds high - strength fibers. It is green and environmentally friendly, reduces carbon emissions. This low - carbon repair material has a high bonding strength with concrete, is firmly bonded, is not easy to crack, has a small dosage, and the concrete precast components after repair have high compressive and flexural strengths, small color difference after repair, and the repair process is simple and efficient.

[0050] (2) The mineral powder, steel slag, graded sand, and high - strength fibers in component A all contribute to improving the compressive strength and flexural strength of the repaired concrete precast components.

[0051] Sodium silicate in component B of the present invention can not only improve the compressive strength of concrete precast components, but also improve the bonding strength of concrete precast components and reduce the dry shrinkage rate. Sodium hydroxide in component B can shorten the setting time of concrete precast components and improve the repair efficiency of concrete cracks.

[0052] The limestone and quartz powder in component C can improve the corrosion resistance of concrete precast components, extend the service time, and improve its service life; at the same time, quartz powder can further improve the mechanical strength of concrete precast components. The added component C of the present invention can improve the compressive, flexural strengths and bonding strength of concrete precast components, reduce the dry shrinkage rate, and shorten the setting time.

[0053] (4) The low - carbon repair material of the present invention through the synergistic effect between component A, component B and component C, and at the same time by limiting the particle size of each component raw material to improve the density of the repair material, so that the low - carbon repair material of the present invention has good compressive strength and flexural strength, makes the low - carbon repair material and concrete have excellent adhesiveness, can effectively reduce the cracking rate of concrete precast components and improve its service life. The low - carbon repair material of the present invention also has the advantages of low dry shrinkage rate, short initial setting and final setting times, which helps to shorten the repair time of concrete cracks and improve the repair efficiency.

[0054] In addition, the raw materials used in the repair material of the present invention

[0055] (5) The present invention designs different repair methods for different types of cracks, which can not only improve the repair efficiency of cracks, but also improve the mechanical strength and service life of the concrete precast components after repair. Description of the Drawings

[0056] Figure 1 Schematic diagram showing the measurement of crack width using a crack card;

[0057] Figure 2 Schematic diagram showing the chiseling of a V-shaped opening along the crack. Detailed Description of the Invention

[0058] The present invention will be described in detail below, and the features and advantages of the present invention will become clearer and more definite along with these descriptions.

[0059] The repair (usage) method of the present invention uses the low-carbon repair material described in the present invention for repair. The repair method is the usage method of the low-carbon repair material, and the repair method includes the following steps:

[0060] Measure the crack width with a crack card, confirm the crack defects of the precast concrete member, and determine the corresponding repair method according to the crack defects.

[0061] Specifically, the fissures generated in the member under the action of stress or environment (or both simultaneously). Commonly, there are several situations such as surface microcracks, general cracks, through cracks, and cracking. Cracks are classified into the following categories:

[0062] (1) Large cracks (including through cracks): with a width greater than 0.5 mm or a depth greater than the cover layer.

[0063] (2) Small cracks: with a width greater than 0.20 mm and less than 0.50 mm, and a depth less than the cover layer.

[0064] (3) Microcracks: with a width less than 0.20 mm and not densely distributed.

[0065] (4) Turtle cracks: obvious surface cracks with a width less than 0.20 mm.

[0066] It should be noted that small cracks or even very small cracks at the edge of the precast concrete member may mean that the concrete fragments cannot be separated. Therefore, the area needs to be gently tapped with a steel hammer or steel bar to observe whether the concrete falls off. In this case, if it falls off, this defect should be regarded as spalling and repaired accordingly.

[0067] Specifically, (1) For turtle cracks:

[0068] Cracks located in the shallow surface layer, with a width not exceeding 0.2 mm and not yet separated. The area with microcracks can be gently polished with fine sandpaper so that the particles formed by polishing fill the microcrack area; or a coarse sponge can be used to dip in dry cement powder and squeeze the microcrack area until the dry powder fills the microcracks densely, and then some surface repair mortar is applied to achieve the purpose of beauty and protection.

[0069] For members with large - area cracks, after the above - mentioned repairs, an imitation fair - faced concrete coating shall be used for the whole - ring painting. After removing the loose concrete on the surface, if there are signs of segregation or other major defects, an investigation shall be carried out and appropriate methods shall be used for repair.

[0070] (2) For micro - cracks:

[0071] Micro - cracks with a width less than 0.05 mm do not need to be treated.

[0072] For cracks with a width between 0.05 mm and 0.2 mm and a depth not exceeding the cover thickness, generally no repair is required. When there are aesthetic requirements, surface painting can be done. However, the micro - cracks need to be marked to evaluate their development. The crack ends, widths, and inspection dates shall be recorded on the inspection sheet, as Figure 1 shown.

[0073] For cracks with a width between 0.05 mm and 0.2 mm and a depth greater than the cover thickness, the repair method refers to that for small cracks.

[0074] (3) For small cracks:

[0075] For small cracks with a width between 0.2 mm and 0.5 mm and a depth less than the cover, to prevent the member from being corroded by steel bars, especially in parts with a thin steel - bar cover, epoxy - based liquid is often used for crack repair.

[0076] Specifically, the usage method for small cracks includes:

[0077] Step a: Cut a groove with an angle of 40 - 45° and a depth of 15 - 20 mm along both sides of the crack, then chisel out a V - shaped opening, and chisel out a closed area along the crack at the V - shaped opening;

[0078] Step b: Grind the surface of the closed area, clean the ground surface to make it smooth and clean, fill the epoxy - based liquid into the closed area, cure it in the shade naturally, and after the epoxy - based liquid solidifies, use the low - carbon repair material to finish the surface treatment of the repair surface;

[0079] Step c: After the low - carbon repair material solidifies, use fine sandpaper to grind it to fade the repair trace at the boundary.

[0080] Preferably, the usage method includes:

[0081] Step a: Use a diamond blade (blade) or similar tool to cut a groove with an angle of about 45° and a depth of 15 - 20 mm along both sides of the crack, then use a sledgehammer or chisel to chisel out a V - shaped opening, as Figure 2 shown, check the crack depth, confirm whether it is a small crack, and verify that no steel bars are damaged.

[0082] At the V-shaped opening, clear a closed area along the crack with a width of about 15 mm to 20 mm and a length that extends 20 mm to 50 mm at both ends of the crack.

[0083] Step b: Use a wire brush to polish the new concrete surface and thoroughly clean the polished surface (either with a hair dryer or manually).

[0084] If there are impurities such as oil stains, it is also necessary to wipe with acetone and dry. After the repaired area is air-dried, fill the epoxy-based liquid into the closed area, cure it naturally in the shade, and pay attention that no water should penetrate before solidification. After solidification, finish the surface treatment of the repaired surface with the low-carbon repair material described in the present invention.

[0085] Step c: After the curing is completed, use fine sandpaper (≥400 mesh) to polish and fade the boundary repair marks.

[0086] (4) For large cracks:

[0087] If the crack width is greater than 0.5 mm or the depth exceeds the protective layer, or there are a large number of connected small cracks, it is necessary to seriously analyze the root cause of the problem to ensure that the integrity of the concrete is not damaged. If the crack is very serious, it should be scrapped.

[0088] Otherwise, the usage method for large cracks includes:

[0089] Step 1: Drill holes along the crack at intervals of about 20 - 40 cm, and then clean the crack.

[0090] Step 2: Place the injection tube in the drilled hole, seal the crack surface with a sealant, wait for the sealant to harden, inject the low-carbon repair material into the crack through the injection tube, wait for the low-carbon repair material to harden, remove the injection tube, and polish the surface.

[0091] Specifically, the repair method for large cracks is as follows:

[0092] Step 1: Drill holes along the crack at intervals of about 20 - 40 cm, preferably at intervals of about 30 cm, and clean the crack with compressed air.

[0093] Step 2: Place the injection tube in the above-mentioned drilled hole, seal the crack on the surface, especially around the drilled hole, to avoid leakage of the low-carbon repair material during injection. Wait for the sealant to harden, inject the low-carbon repair material into the crack through the injection tube placed in the drilled hole, and ensure that it flows along the entire crack. After the low-carbon repair material flows out, the grouting needle tube should be blocked or obstructed. If the slurry never flows out from other exhaust ports, then after injecting as much low-carbon repair material as possible from one injection port, continue to inject from the adjacent injection port.

[0094] After the low-carbon repair material hardens (at least 24 hours after the injection is completed), the grouting needle tube should be removed and the surface should be polished.

[0095] Preferably, fine sandpaper (≥400 mesh) is used for polishing to fade the boundary repair marks.

[0096] Example

[0097] The present invention will be further elaborated through specific examples below. These examples are only for illustrating the present invention and not for limiting the scope of the present invention. The raw materials used in the examples of the present invention are all commercially available.

[0098] Example 1

[0099] A low-carbon repair material for concrete precast components, the low-carbon repair material for concrete precast components includes component A, component B and component C.

[0100] Component A is obtained by mixing the following raw materials in parts by weight: 12 parts by weight of mineral powder, 3 parts by weight of industrial solid waste powder, 3 parts by weight of steel slag, 60 parts by weight of graded sand, and 4 parts by weight of high-strength fiber. The high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 2:1. The length of the high-strength fiber is 2 cm.

[0101] Component B is obtained by mixing the following raw materials in parts by weight: 20 parts by weight of sodium silicate, 2 parts by weight of sodium hydroxide, and 3 parts by weight of water.

[0102] Component C is obtained by mixing the following raw materials in parts by weight: 3 parts by weight of limestone powder and 3 parts by weight of quartz powder.

[0103] In this example, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder used are all <5 μm, the particle size of the graded sand is 0.5 - 1.0 mm, and the particle size of the steel slag is 5 - 15 mm.

[0104] A preparation method of a low-carbon repair material, the preparation method includes the following steps:

[0105] Mix the raw materials in component A evenly at a stirring speed of 3000 rpm.

[0106] Mix the raw materials in component B evenly at a stirring speed of 1500 rpm, and mix the raw materials in component C evenly at a stirring speed of 1500 rpm.

[0107] Finally, mix the evenly mixed component A, component B and component C evenly at a stirring speed of 3000 rpm.

[0108] Example 2

[0109] A low-carbon repair material for concrete precast components, the low-carbon repair material for concrete precast components includes component A, component B and component C.

[0110] The A component is obtained by mixing the following raw materials in parts by weight: 15 parts by weight of mineral powder, 4 parts by weight of industrial solid waste powder, 4 parts by weight of steel slag, 80 parts by weight of graded sand, and 6 parts by weight of high-strength fiber. The high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 3:1. The length of the high-strength fiber is 2 cm.

[0111] The B component is obtained by mixing the following raw materials in parts by weight: 15 parts by weight of water glass, 1 part by weight of sodium hydroxide, and 1 part by weight of water.

[0112] The C component is obtained by mixing the following raw materials in parts by weight: 4 parts by weight of limestone powder and 4 parts by weight of quartz powder.

[0113] In this embodiment, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder, and quartz powder used are all <5 μm, the particle size of the graded sand is 0.5 - 1.0 mm, and the particle size of the steel slag is 5 - 15 mm.

[0114] A preparation method of a low-carbon repair material, the preparation method comprising the following steps:

[0115] Mix the raw materials in the A component evenly at a stirring speed of 2000 rpm.

[0116] Mix the raw materials in the B component evenly at a stirring speed of 1000 rpm, and mix the raw materials in the C component evenly at a stirring speed of 1000 rpm.

[0117] Finally, mix the evenly mixed A component, B component, and C component evenly at a stirring speed of 2000 rpm.

[0118] Example 3

[0119] A low-carbon repair material for concrete precast members, the low-carbon repair material for concrete precast members comprising an A component, a B component, and a C component.

[0120] The A component is obtained by mixing the following raw materials in parts by weight: 10 parts by weight of mineral powder, 1 part by weight of industrial solid waste powder, 1 part by weight of steel slag, 40 parts by weight of graded sand, and 2 parts by weight of high-strength fiber. The high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 1:1. The length of the high-strength fiber is 2 cm.

[0121] The B component is obtained by mixing the following raw materials in parts by weight: 30 parts by weight of water glass, 4 parts by weight of sodium hydroxide, and 4 parts by weight of water.

[0122] The C component is obtained by mixing the following raw materials in parts by weight: 2 parts by weight of limestone powder and 2 parts by weight of quartz powder.

[0123] In this embodiment, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder used are all < 5 μm, the particle size of the graded sand is 0.5 - 1.0 mm, and the particle size of the steel slag is 5 - 15 mm.

[0124] A preparation method of a low-carbon repair material, the preparation method comprising the following steps:

[0125] Mix the raw materials in component A evenly at a stirring speed of 4000 rpm.

[0126] Mix the raw materials in component B evenly at a stirring speed of 2000 rpm, and mix the raw materials in component C evenly at a stirring speed of 2000 rpm.

[0127] Finally, mix the evenly mixed component A, component B and component C together evenly at a stirring speed of 4000 rpm.

[0128] Example 4

[0129] A low-carbon repair material for concrete precast members, the low-carbon repair material for concrete precast members comprising component A, component B and component C.

[0130] Component A is obtained by mixing the following raw materials in parts by weight: 11 parts by weight of mineral powder, 2 parts by weight of industrial solid waste powder, 2 parts by weight of steel slag, 50 parts by weight of graded sand, and 5 parts by weight of high-strength fiber. The high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 2.5:1. The length of the high-strength fiber is 1 cm.

[0131] Component B is obtained by mixing the following raw materials in parts by weight: 25 parts by weight of water glass, 3 parts by weight of sodium hydroxide, and 2 parts by weight of water.

[0132] The C component is obtained by mixing the following raw materials in parts by weight: 2 parts by weight of limestone powder and 4 parts by weight of quartz powder.

[0133] In this embodiment, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder used are all < 5 μm, the particle size of the graded sand is 0.5 - 1.0 mm, and the particle size of the steel slag is 5 - 15 mm.

[0134] A preparation method of a low-carbon repair material, the preparation method comprising the following steps:

[0135] Mix the raw materials in component A evenly at a stirring speed of 2500 rpm.

[0136] Mix the raw materials in Component B evenly at a stirring speed of 2000 rpm, and mix the raw materials in Component C evenly at a stirring speed of 1500 rpm.

[0137] Finally, mix the evenly mixed Component A, Component B and Component C together evenly at a stirring speed of 3500 rpm.

[0138] Example 5

[0139] A low-carbon repair material for concrete precast components, the low-carbon repair material for concrete precast components is similar to that in Example 1, except that: the high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 1.5:1. The length of the high-strength fiber is 3 cm.

[0140] Example 6

[0141] A low-carbon repair material for concrete precast components, the low-carbon repair material for concrete precast components is similar to that in Example 1, except that: the high-strength fiber is carbon fiber.

[0142] Comparative Example

[0143] Comparative Example 1

[0144] A low-carbon repair material for concrete precast components, the low-carbon repair material for concrete precast components includes Component A and Component B.

[0145] Component A is obtained by mixing the following raw materials by weight: 12 parts by weight of mineral powder, 3 parts by weight of industrial solid waste powder, 3 parts by weight of steel slag, 60 parts by weight of graded sand, and 4 parts by weight of high-strength fiber. The high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 2:1. The length of the high-strength fiber is 2 cm.

[0146] Component B is obtained by mixing the following raw materials by weight: 20 parts by weight of water glass, 2 parts by weight of sodium hydroxide, and 3 parts by weight of water.

[0147] In this example, the particle sizes of the mineral powder and the industrial solid waste powder are both <5 μm, the particle size of the graded sand is 0.5 - 1.0 mm, and the particle size of the steel slag is 5 - 15 mm.

[0148] Comparative Example 2

[0149] A low-carbon repair material for concrete precast components, the low-carbon repair material for concrete precast components includes Component A and Component C.

[0150] The component A is obtained by mixing the following raw materials in parts by weight: 12 parts by weight of mineral powder, 3 parts by weight of industrial solid waste powder, 3 parts by weight of steel slag, 60 parts by weight of graded sand, and 4 parts by weight of high-strength fiber. The high-strength fiber is a mixture of carbon fiber and aramid fiber, and the mass ratio of the carbon fiber to the aramid fiber is 2:1. The length of the high-strength fiber is 2 cm.

[0151] The component C is obtained by mixing the following raw materials in parts by weight: 3 parts by weight of limestone powder and 3 parts by weight of quartz powder.

[0152] In this example, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder used are all <5 μm, the particle size of the graded sand is 0.5 - 1.0 mm, and the particle size of the steel slag is 5 - 15 mm.

[0153] Comparative Example 3

[0154] A low-carbon repair material for concrete precast components, which is similar to Example 1, except that: the length of the high-strength fiber is 4 cm. The particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder used are 10 - 15 μm, the particle size of the graded sand is 1.3 - 1.5 mm, and the particle size of the steel slag is 30 - 50 mm.

[0155] Experimental Example

[0156] Mechanical Property Test of Experimental Example 1

[0157] The cracks of the concrete precast components repaired with the low-carbon repair materials described in Examples 1 - 6 and Comparative Examples 1 - 3 were respectively repaired, and then the mechanical property tests were carried out in accordance with JGJ / 70 - 2009 "Test Methods for Basic Properties of Building Mortars". The test results are shown in Table 1.

[0158] Table 1

[0159]

[0160]

[0161] As can be seen from Table 1, the 28-day compressive strength of the low-carbon repair materials in Examples 1 - 6 is above 72.7 MPa, the 28-day flexural strength is above 9.5 MPa, their 7-day bond strength is above 1.75 MPa, the 14-day bond strength is above 1.85 MPa, the 28-day drying shrinkage rate is below 0.05%, the initial setting time is within 20 min, and the final setting time is within 43 min. It shows that the low-carbon repair material described in the present invention has good compressive strength and flexural strength, high 7-day and 14-day bond strength, low 28-day drying shrinkage rate, and short initial setting and final setting times of the low-carbon repair material described in the present invention.

[0162] Compared with Comparative Example 1, Component C was not added in Comparative Example 1. The compressive strength, flexural strength, and bonding strength of Comparative Example 1 were significantly reduced, and the dry shrinkage rate, initial setting time, and final setting time of Comparative Example 1 increased. It shows that the addition of Component C helps to improve the compressive strength, flexural strength, and bonding strength of the low-carbon repair material, and reduce the dry shrinkage rate, initial setting time, and final setting time.

[0163] Compared with Comparative Example 2, Component B was not added in Comparative Example 2. The compressive strength, flexural strength, and bonding strength of Comparative Example 2 were reduced, its dry shrinkage rate increased, and the initial setting time and final setting time became longer. It shows that the addition of Component B helps to improve the compressive strength, flexural strength, and bonding strength of the low-carbon repair material. At the same time, the addition of Component B helps to reduce the dry shrinkage rate, shorten the initial setting time and final setting time, and improve the repair efficiency.

[0164] Compared with Comparative Example 3, the length of the high-strength fiber in Comparative Example 3 was longer, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder, quartz powder, and steel slag used were larger, and the particle size of the graded sand decreased. The compressive strength, flexural strength, and bonding strength of Comparative Example 3 were significantly reduced, and the dry shrinkage rate, initial setting time, and final setting time of Comparative Example 3 increased. It shows that the length of the high-strength fiber, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder, quartz powder, steel slag, and graded sand all affect the strength, dry shrinkage rate, and setting time of the low-carbon repair material. Only when the length of the high-strength fiber, the particle sizes of the mineral powder, industrial solid waste powder, limestone powder, quartz powder, steel slag, and graded sand are within the scope defined in the present invention, it is beneficial to improve the strength of the low-carbon repair material, reduce the dry shrinkage rate, and shorten the setting time.

[0165] The present invention has been described in detail above in combination with specific embodiments and exemplary examples. However, these descriptions should not be construed as limitations on the present invention. Those skilled in the art understand that without departing from the spirit and scope of the present invention, various equivalent substitutions, modifications, or improvements can be made to the technical solutions and their implementation manners of the present invention, and these all fall within the scope of the present invention. The protection scope of the present invention shall be subject to the appended claims.

Claims

1. A low-carbon repair material for precast concrete components, characterized in that, The low-carbon repair material for concrete precast components includes component A; Component A includes raw materials in the following weight parts: 10-15 weight parts of mineral powder, 1-4 weight parts of industrial solid waste powder, 1-4 weight parts of steel slag, 40-80 weight parts of graded sand, and 2-6 weight parts of high-strength fiber.

2. The low-carbon repair material for precast concrete components according to claim 1, characterized in that, The low-carbon repair material for concrete precast components further includes component B; Component B includes raw materials in the following weight parts: 15-30 weight parts of water glass, 1-4 weight parts of sodium hydroxide, and 1-4 weight parts of water.

3. The low-carbon repair material for precast concrete components according to claim 1, wherein The low-carbon repair material for concrete precast components further includes component C; Component C includes raw materials in the following weight parts: 2-4 weight parts of limestone powder and 2-4 weight parts of quartz powder.

4. The low-carbon repair material for concrete precast components according to any one of claims 1 to 3, characterized in that the particle sizes of the mineral powder, industrial solid waste powder, limestone powder and quartz powder are all < 10 μm; and / or, the particle size of the graded sand is 0.3-1.25 mm; and / or, the particle size of the steel slag is 5-30 mm.

5. The low-carbon repair material for concrete precast components according to claim 1, characterized in that the high-strength fiber is selected from one or more of carbon fiber, aramid fiber, basalt fiber, polyphenylene sulfide fiber, polyurethane fiber, polyamide fiber; and / or, the length of the high-strength fiber is 1-3 cm.

6. The low-carbon repair material for concrete precast components according to claim 5, characterized in that the high-strength fiber is a mixture of carbon fiber and aramid fiber.

7. The low-carbon repair material for concrete precast components according to claim 6, characterized in that the mass ratio of the carbon fiber to the aramid fiber is (1-3):

1.

8. A preparation method of a low-carbon repair material for a precast concrete member according to any one of claims 1 to 7, characterized in that, The preparation method includes: Mixing the raw materials in component A evenly at a stirring speed of 2000-4000 rpm.

9. A method for using the low-carbon repair material for precast concrete components according to any one of claims 1 to 7, characterized in that, The using method includes the step of using the low-carbon repair material to fill small cracks, wherein the width of the small cracks is between 0.2 mm and 0.5 mm, and the depth is less than the protective layer.

10. According to the using method of claim 9, the using method includes the following steps: Step a, cutting a groove at each end of the small crack along the length direction of the small crack, each groove having an angle of 40-45° and a depth of 15-20 mm, then opening a V-shaped opening, and chiseling out a closed area along the small crack at the V-shaped opening; Step b, grinding the surface of the closed area to form a grinding surface, cleaning the grinding surface to make the grinding surface smooth and clean, filling the epoxy-based liquid into the closed area, curing in a natural shade and drying, and after the epoxy-based liquid solidifies, performing a finishing treatment on the repair surface with the low-carbon repair material; Step c, after the low-carbon repair material solidifies, grinding it with fine sandpaper to fade the boundary repair marks.

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