Early-strength UHPC (Ultra High Performance Concrete) pavement repair material as well as preparation method and use method thereof

Abstract

The invention discloses an early-strength UHPC (Ultra High Performance Concrete) pavement repair material as well as a preparation method and a use method thereof, and particularly relates to the technical field of UHPC pavement repair materials. The material comprises a gel material, aggregate, a fiber material and an additive, wherein the gel material comprises cement, silica fume, nano calcium carbonate, fly ash sinking beads, modified C-S-H nanocrystals, superfine mineral powder and silicon dioxide microspheres; the aggregate and fiber material comprises quartz sand, limestone powder, copper-plated steel fibers, quartz powder, temperature shrinkage fibers, carbon nanotubes and graphene; the additives comprise a retarder, a defoaming agent, water and a water reducing agent. According to the early-strength UHPC pavement repairing material, a double-cement system is adopted, and the problem that the early strength of a traditional material is insufficient is solved; meanwhile, a fiber compounding scheme is adopted, so that both tensile strength and crack resistance are considered; a layered pouring process is adopted, and steam curing is avoided through interface agent optimization.

Description

Technical Field

[0001] The present invention relates to the technical field of UHPC pavement repair materials, and in particular to an early-strength UHPC pavement repair material and a preparation method and a use method thereof. Background Art

[0002] Ultra-high-performance concrete (UHPC) is hailed as the most promising cement-based material of the 21st century. It possesses exceptional mechanical and durability properties and is environmentally friendly. With its exceptional strength, toughness, workability, and durability, UHPC has become a research hotspot in concrete structure construction both domestically and internationally, finding increasing application in municipal administration, construction, urban renewal, and other fields.

[0003] However, under the influence of factors such as long-term high-intensity vehicle operation and natural aging, many urban roads using ultra-high performance concrete have suffered varying degrees of damage, such as cracks, potholes, rutting, and subsidence. These damages not only affect the flatness and service life of the road, but also have a serious impact on traffic safety and driving comfort.

[0004] Compared to asphalt pavements, UHPC pavements offer higher compressive strength and a higher elastic modulus, but lower toughness. Furthermore, the shrinkage and thermal expansion coefficients of new UHPC materials used for repairs may differ from those of the old pavement. When the old pavement is damaged, stress concentration can easily cause cracks at the interface between the repair material and the original structure, leading to bond failure. While UHPC offers superior mechanical properties compared to asphalt, it takes longer to cure, meaning that repaired areas will take longer to reopen to traffic—a significant consideration for busy roads.

[0005] Traditional repair materials such as ordinary concrete and epoxy resin have a long curing time, usually requiring ≥8 hours, and low early strength, which almost takes 3 days to reach 40MPa. The short-term strength is generally lower than 20MPa, which cannot meet the needs of rapid traffic opening. Chinese patent CN101811847A discloses a cement concrete pavement repair material, which is prepared by the following raw material ratio (by weight): 380 parts of cement, 1200 parts of crushed stone, 650 parts of sand, and 40 parts of admixture; wherein the admixture is mixed with the following raw materials in the following ratio (by weight): 1 part of naphthalene-based water reducer, 1 part of anhydrous sodium sulfate, 1.5 parts of dispersible rubber powder, 0.8 part of sodium nitrite, 0.8 part of powdered instant sodium sulfate, 0.4 part of sepiolite wool, and 4.5 parts of Class I fly ash; using this repair material to repair damaged pavement, the pavement does not crack, has good adhesion to the base layer, good paving properties, and high early strength. However, this patent still requires 3 days for the strength to reach 40MPa, and ordinary cement concrete has a shorter curing time than ultra-high performance concrete, but it still takes more than 8 hours before it can be opened to traffic.

[0006] Directly using UHPC materials for repair, such as Chinese patents CN108558304A and CN105198339A, although these patents also use gel materials, aggregates and additives, these patents are mainly for paving road base, not for rapid repair. Therefore, the raw materials used need to consider high compressive strength and flexural strength. The commonly used UHPC materials have a long solidification time and require at least 7 days, or even 28 days of curing before their performance can be tested. They cannot meet the requirements of achieving the expected strength in a short time and shortening the repair time.

[0007] Therefore, how to improve the repair strength of ultra-high performance concrete pavement and shorten the repair time is a difficult problem that needs to be solved urgently in the repair of ultra-high performance concrete pavement. Summary of the Invention

[0008] To this end, the present invention provides an early-strength UHPC pavement repair material and a preparation method and a use method thereof to solve the problems in the prior art.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] According to a first aspect of the present invention, an early-strength UHPC pavement repair material is provided, comprising a gel material, aggregate and fiber materials, and additives; wherein the gel material comprises cement, microsilica powder, nano-calcium carbonate, fly ash beads, modified CSH nanocrystals, ultrafine mineral powder, and silica microspheres; the aggregate and fiber materials comprise quartz sand, limestone powder, copper-coated steel fiber, quartz powder, temperature shrinkage fiber, carbon nanotubes, and graphene; and the additives comprise a retarder, a defoamer, water, and a water reducer.

[0011] Furthermore, the cement includes silicate cement and sulphoaluminate cement.

[0012] Furthermore, the materials include gel material: 25-35% silicate cement, 2-10% sulphoaluminate cement, 3-10% microsilica powder, 3-8% fly ash beads, 2-8% ultrafine mineral powder, 0.1-0.5% nano calcium carbonate, 1-5% modified CSH nanocrystals, and 0.1-0.5% silica microspheres; aggregate and fiber materials: 20-35% quartz sand, 2-10% quartz powder, 2-10% limestone powder, 1.5-2.5% copper-plated steel fiber, 0.3-0.8% temperature shrinkage fiber, 0.5-1.5% carbon nanotubes, and 1-3% graphene; additives include 0.5-0.8% water reducer, 0.01-0.05% retarder, 0.1-0.6% defoamer, and 7-10% water.

[0013] As an example, the copper-coated steel fiber has a length of 12-15 mm;

[0014] The temperature shrinkage fiber is polyvinyl alcohol (PVA) fiber;

[0015] The diameter of the carbon nanotubes is 5-20 nm.

[0016] Furthermore, the water reducer is a polycarboxylic acid high-efficiency water reducer.

[0017] According to the second aspect of the present invention, a method for preparing the above-mentioned early-strength UHPC pavement repair material is provided, the method comprising:

[0018] Step 1: Add the gel material into a blender and stir at a low speed of 100-200 rpm to obtain a preliminary mixed material;

[0019] Step 2: Add additives to the preliminary mixed material and continue stirring at a high speed of 400-600 rpm to form a uniform slurry;

[0020] Step 3: Add aggregate and fiber material to the slurry and continue stirring at a medium speed of 300-400 rpm to obtain early-strength UHPC pavement repair material.

[0021] The present invention adopts low-speed powder mixing → high-speed pulping → medium-speed fiber adding to avoid fiber agglomeration.

[0022] Furthermore, in step 1, the stirring time is 1-2 min; in step 2, the stirring time is 3-5 min; and in step 3, the stirring time is 1-3 min.

[0023] According to a third aspect of the present invention, a method for repairing a UHPC pavement using the early-strength UHPC pavement repair material as described above is provided, the method comprising:

[0024] Step 1: Base surface treatment

[0025] Use high-pressure water jets to remove loose materials from damaged road surfaces to a solid base layer, forming a rough, clean interface. Clean and dry the base surface. Spray an interface agent on the base surface and pre-embed anchor steel bars in the base surface.

[0026] Step 2: Material pouring and molding

[0027] Pouring the bottom repair layer: Pour the early-strength UHPC pavement repair material onto the treated base surface to form the bottom repair layer; before the bottom repair layer begins to set, pour the wear-resistant layer; after defoaming treatment, cover with a water-retaining film and maintain at room temperature.

[0028] As an example, in step 1, a high-pressure water jet with a pressure of ≥30 MPa is used; and HRB400 threaded steel bars with a depth of ≥5 cm are pre-buried in a 20 cm×20 cm grid.

[0029] Furthermore, in step 1, the interface agent is a mixture of epoxy resin and silane coupling agent.

[0030] Furthermore, in step 1, the mass ratio of the epoxy resin to the silane coupling agent is 2.5-3.5:1. As an example, 3:1 is preferred.

[0031] Furthermore, in the step 2, the material of the wear-resistant layer is a mixture of early-strength UHPC pavement repair material and 0.3-0.8% corundum.

[0032] Defoaming treatment: Use a 50±5Hz high-frequency vibrator to vibrate for 5-10 seconds, which can defoam and compact the material at the same time.

[0033] The present invention has the following advantages:

[0034] The early-strength UHPC pavement repair material of the present invention adopts a dual cement system (silicate + sulphoaluminate), which solves the problem of insufficient early strength of traditional materials; at the same time, it adopts a fiber compounding scheme (copper-plated steel fiber + PVA fiber + nanomaterial) to take into account both tensile strength and crack resistance; adopts a layered casting process and achieves steam-free curing through interface agent optimization.

[0035] The early-strength UHPC pavement repair material of the present invention accelerates the hydration reaction through a compound system of sulphoaluminate cement and silicate cement, combined with a compound of modified CSH nanocrystals and nano-calcium carbonate, greatly shortening the setting time, thereby shortening the road repair time, reducing traffic interruption and congestion time, and can be quickly opened to traffic after repair.

[0036] The early-strength UHPC pavement repair material of the present invention can reach the expected strength in a short period of time, usually reaching initial setting within 1 hour and final setting within about 2 hours, shortening the repair time. Moreover, the strength after 5 hours can meet the expected vehicle traffic requirements. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can derive other implementation drawings based on the provided drawings without inventive effort.

[0038] The structures, proportions, sizes, etc. illustrated in this specification are intended only to complement the contents disclosed herein and to facilitate understanding and reading by persons familiar with the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall still fall within the scope of the technical contents disclosed herein.

[0039] Figure 1 A schematic plan view of a steel bar provided in Example 5 of the present invention;

[0040] Figure 2 This is an actual picture of the pavement after being repaired by an early-strength UHPC pavement repair material provided in Example 5 of the present invention. DETAILED DESCRIPTION

[0041] The following describes the implementation of the present invention using specific embodiments. Those skilled in the art will readily understand the other advantages and benefits of the present invention from the disclosure herein. Obviously, the embodiments described are only a portion of the present invention, not all of it. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are intended to fall within the scope of protection of the present invention.

[0042] Portland cement: Huizhou Tapai Cement Co., Ltd., P·II52.5R;

[0043] Sulphoaluminate cement specifications: Yicheng Anda Special Cement Co., Ltd., rapid hardening grade 52.5;

[0044] Silica fume: Chengdu Qiangbao Construction Engineering Co., Ltd., 92 silica fume;

[0045] Fly ash sinking beads: Chengdu Qiangbao Construction Engineering Co., Ltd., Class F fly ash sinking beads;

[0046] Ultrafine mineral powder: Huizhou Yimeijia Technology Co., Ltd., S105;

[0047] Nano calcium carbonate manufacturer: Foshan Yuanlei Powder Co., Ltd., CAS 471-34-1;

[0048] Modified CSH nanocrystals: Hainan Gongke Zhitong Engineering Technology Co., Ltd., modified CSH;

[0049] Silica microspheres: Chengdu Qiangbao Construction Engineering Co., Ltd., 95% silica microspheres;

[0050] Quartz sand: Longchuan County Tuocheng Zhaojia Quartz Sand Factory, 8-100 mesh quartz sand;

[0051] Quartz powder: 500 mesh quartz powder from Zhaojia Quartz Sand Factory, Tuocheng, Longchuan County;

[0052] Limestone powder: Longchuan County Tuocheng Zhaojia Quartz Sand Factory, 200 mesh limestone powder;

[0053] Copper-coated steel fiber: Hebei Ruohe Metal Products Co., Ltd., 0.2mm*12mm;

[0054] Temperature shrinkage fiber: Ningbo Shike New Material Technology Co., Ltd., polyvinyl alcohol (PVA) fiber;

[0055] Carbon nanotubes: Jiangsu Tiannai Technology Co., Ltd., CAS 308068-56-6;

[0056] Graphene: Beijing Graphene Institute Co., Ltd., CAS1034343-98-0;

[0057] Polycarboxylate high-efficiency water reducer: Xiamen Hebang New Materials Co., Ltd., UHPC special early strength water reducer;

[0058] Retarder: Guangdong Yuesheng Special Building Materials Co., Ltd., UHPC-specific retarder and water-reducing agent;

[0059] Defoaming agent: Xiamen Hebang New Materials Co., Ltd., UHPC special retarding defoaming agent;

[0060] Epoxy resin: Dongguan Ruijiahu Plastic Co., Ltd., bisphenol A epoxy resin;

[0061] Silane coupling agent: Guangzhou Xuanning Chemical Technology Co., Ltd., KH-560.

[0062] Example 1

[0063] This embodiment provides an early-strength UHPC pavement repair material:

[0064] The material includes gel material: 25% silicate cement, 10% sulphoaluminate cement, 6% microsilica fume, 3% fly ash beads, 2% ultrafine mineral powder, 0.1% nano calcium carbonate, 1% modified CSH nanocrystals, and 0.1% silica microspheres;

[0065] Aggregate and fiber materials: quartz sand 35%, quartz powder 2%, limestone powder 2%, copper-coated steel fiber 1.5%, temperature shrinkage fiber 0.3%, carbon nanotube 0.5%, graphene 1%;

[0066] Additives include polycarboxylate high-efficiency water reducer 0.8%, retarder 0.05%, defoamer 0.55%, and water 9.1%.

[0067] The copper-plated steel fiber has a length of 12 mm;

[0068] The temperature shrinkage fiber is polyvinyl alcohol (PVA) fiber;

[0069] The diameter of the carbon nanotubes is 5 nm.

[0070] Example 2

[0071] This embodiment provides an early-strength UHPC pavement repair material:

[0072] The material includes gel material: 35% silicate cement, 2% sulphoaluminate cement, 3% microsilica fume, 8% fly ash beads, 8% ultrafine mineral powder, 0.5% nano calcium carbonate, 1% modified CSH nanocrystals, and 0.5% silica microspheres;

[0073] Aggregate and fiber materials: quartz sand 20%, quartz powder 2%, limestone powder 2%, copper-coated steel fiber 2.5%, temperature shrinkage fiber 0.8%, carbon nanotube 1.5%, graphene 3%;

[0074] Additives include polycarboxylic acid high-efficiency water reducer 0.5%, retarder 0.01%, defoamer 0.59%, and water 9.1%.

[0075] The copper-plated steel fiber has a length of 13 mm;

[0076] The temperature shrinkage fiber is polyvinyl alcohol (PVA) fiber;

[0077] The diameter of the carbon nanotubes is 100 nm.

[0078] Example 3

[0079] This embodiment provides an early-strength UHPC pavement repair material:

[0080] The material includes gel material: 28% silicate cement, 5% sulphoaluminate cement, 5% microsilica fume, 4% fly ash beads, 4% ultrafine mineral powder, 0.25% nano calcium carbonate, 2.5% modified CSH nanocrystals, and 0.22% silica microspheres;

[0081] Aggregate and fiber materials: quartz sand 28%, quartz powder 5%, limestone powder 5%, copper-coated steel fiber 2%, temperature shrinkage fiber 0.4%, carbon nanotube 1%, graphene 2%;

[0082] Additives include polycarboxylic acid high-efficiency water reducer 0.5%, retarder 0.03%, defoamer 0.1%, and water 7%.

[0083] The copper-plated steel fiber has a length of 15 mm;

[0084] The temperature shrinkage fiber is polyvinyl alcohol (PVA) fiber;

[0085] The diameter of the carbon nanotubes is 20 nm.

[0086] Example 4

[0087] This embodiment provides a method for preparing the early-strength UHPC pavement repair material of Examples 1-3:

[0088] Step 1: Add the gel material into a blender and stir at a low speed of 100-200 rpm for 1-2 minutes to obtain a preliminary mixed material;

[0089] Step 2: Add additives to the preliminary mixed material and continue stirring at a high speed of 400-600 rpm for 3-5 minutes to form a uniform slurry;

[0090] Step 3: Add aggregate and fiber material to the slurry, continue stirring at a medium speed of 300-400 rpm for 1-3 minutes, and stir evenly to obtain the early-strength UHPC pavement repair material.

[0091] Example 5

[0092] This embodiment provides a method for using an early-strength UHPC pavement repair material:

[0093] Step 1: Base surface treatment

[0094] Use a high-pressure water jet of ≥30MPa to remove loose materials from the damaged area of ​​the road surface to the solid base, forming a rough and clean interface. Clean and dry the base surface; spray the interface agent (epoxy resin: silane coupling agent = 3:1) on the base surface, and pre-embed anchor steel bars in the base surface. Pre-embed HRB400 threaded steel bars with a depth of ≥5cm according to a 20cm×20cm grid. The steel bar diagram is shown as follows: Figure 1 As shown;

[0095] Step 2: Material pouring and molding

[0096] Pouring the bottom repair layer: Pour the early-strength UHPC pavement repair material onto the treated base surface to form the bottom repair layer; before the initial setting of the bottom repair layer, pour the wear-resistant layer; after defoaming treatment (vibrate with a 50±5Hz high-frequency vibrator for 5-10 seconds), cover with a water-retaining film and maintain at room temperature.

[0097] The material of the wear-resistant layer is a mixture of early-strength UHPC pavement repair material and 0.5% corundum.

[0098] The road surface after repairing using the material of Example 1 is as follows Figure 2 shown.

[0099] The present invention has been tested without spraying the interface agent on the base surface, but steam curing is required to achieve the expected effect. Therefore, subsequent tests all spray the interface agent on the base surface to achieve steam-free curing.

[0100] Comparative Example 1

[0101] This comparative example provides a method for preparing a UHPC material:

[0102] A high-performance, low-cost UHPC material is prepared by mixing a cementitious material, coarse and fine aggregates, a water reducer, reinforcing and toughening fibers, and water: the UHPC material has a water-to-cement ratio of 0.15; the water reducer is used in an amount of 1.0% by weight of the cementitious material; the reinforcing and toughening fibers account for 2% of the total volume of the UHPC material; the cementitious material and coarse and fine aggregates are composed of the following components, by weight: 100 parts of cement, 10 parts of silica fume, 12 parts of ultrafine mineral admixture, 9 parts of ground copper tailings powder, 30 parts of raw copper tailings, 100 parts of sand, and 100 parts of crushed stone; the ground copper tailings powder has a particle size of 1 to 12 μm; and the raw copper tailings has a particle size of 0.075 mm to 0.15 mm. The water reducer is a powdered polycarboxylate water reducer; the reinforcing and toughening fibers are polymer fibers; the cement is ordinary Portland cement with a strength grade of 525; the ultrafine mineral admixture is a mixture of fly ash and quartz powder; the sand is natural river sand; and the crushed stone has a particle size of 3 to 8 mm. Preparation method: Cement, silica fume, ultrafine mineral admixture, ground copper tailings powder, raw copper tailings, sand, water reducer, and water are mixed in the above proportions and stirred thoroughly. The reinforcing and toughening fibers are then added to produce a UHPC mixture.

[0103] Comparative Example 2

[0104] This comparative example provides an ultra-high performance cement-based composite material, the volume percentages of which are as follows:

[0105] A high-performance cement-based composite material comprises a binder, water, and a water reducer. Cement (PI cement with a strength grade of 52.5) ​​accounts for 20% by volume, while the mineral admixtures (silica fume and fly ash) account for 52.2% by volume. A polycarboxylate water reducer (powder) is used, achieving a water reduction rate of 30%, and its usage is 2% of the binder.

[0106] Specifically: cement 20%, silica fume 13.5%, fly ash 38.7%, water 23%, and water reducer 3.8%.

[0107] The raw materials are mixed to obtain an ultra-high performance cement-based composite material.

[0108] Comparative Example 3

[0109] This comparative example provides a cement-based composite material:

[0110] 380 parts of sulphoaluminate cement, 1200 parts of gravel, 650 parts of river sand, and 40 parts of admixture; the admixture is prepared by mixing the following raw materials in the following proportions (by weight): 1 part of naphthalene-based water reducer, 1 part of anhydrous sodium sulfate, 1.5 parts of dispersible rubber powder, 0.8 part of sodium nitrite, 0.8 part of powdered instant sodium sulfate, 0.4 part of sepiolite, and 4.5 parts of Class I fly ash; during production, the raw materials of the admixture are first mixed uniformly in a powder mixer according to proportion and then packaged; at the construction site, the admixture is mixed with water, the cement, gravel, and sand according to the proportion, and then stirred for use.

[0111] Comparative Example 4

[0112] This comparative example provides an early-strength UHPC pavement repair material:

[0113] The silicate cement in Example 1 was replaced by sulphoaluminate cement, and the rest was the same as in Example 1.

[0114] Comparative Example 5

[0115] This comparative example provides an early-strength UHPC pavement repair material:

[0116] The sulphoaluminate cement in Example 1 was replaced by silicate cement, and the rest was the same as in Example 1.

[0117] Comparative Example 6

[0118] This comparative example provides an early-strength UHPC pavement repair material:

[0119] The nano-calcium carbonate and modified CSH nanocrystals in Example 1 were replaced with microsilica powder, and the rest were completely the same as in Example 1.

[0120] Comparative Example 7

[0121] This comparative example provides an early-strength UHPC pavement repair material:

[0122] The PVA fiber in Example 1 was replaced with copper-plated steel fiber, and the rest was the same as in Example 1.

[0123] Comparative Example 8

[0124] This comparative example provides an early-strength UHPC pavement repair material:

[0125] The copper-plated steel fiber in Example 1 was replaced with PVA fiber, and the rest was the same as in Example 1.

[0126] Comparative Example 9

[0127] This comparative example provides a method for preparing the early-strength UHPC pavement repair material of Example 1:

[0128] The stirring speed was 300-400 rpm, and the other steps were the same as those in Example 1.

[0129] Experimental Example 1

[0130] The materials obtained from Examples 1-3 and Comparative Examples 1-9 were used to repair roads using the construction method of Example 5. The performance indicators are shown in Tables 1 and 2.

[0131] Bond strength: pull-off test;

[0132] Wear resistance: abrasion value;

[0133] Freeze resistance: mass loss after 300 freeze-thaw cycles;

[0134] Durability: chloride ion diffusion coefficient, salt freeze resistance.

[0135] Table 1

[0136]

[0137]

[0138] Table 2

[0139]

[0140] As can be seen from Tables 1 and 2, the dual cement system, silicate + sulphoaluminate, can make the UHPC pavement repair material have early strength, with a 5h compressive strength of >78MPa, and it can be opened to traffic in 5 hours; while the comparative example 1-35h strength is ≈0, and it takes 18 hours to be open to traffic; the present invention adopts a dual cement system to better balance early strength and late strength; comparative example 4 only uses sulphoaluminate cement, although it can speed up the initial setting time, the initial setting time is too fast, which will cause the construction to solidify before it is completed, affecting subsequent construction, poor workability, and reduced late strength; comparative example 5 only uses silicate cement, the 5h strength is 0, and the opening to traffic is delayed to 18 hours; therefore, the present invention adopts dual cement to synergistically provide rapid hydration (sulphoaluminate) and stable development (silicate).

[0141] Copper-plated steel fiber (1.5-2.5%) provides the main reinforcement, PVA temperature shrinkage fiber (0.3-0.8%) inhibits temperature cracks, and carbon nanotubes + graphene (total amount 1.5-4.5%) fill micro defects; Comparative Example 6 is replaced with microsilica powder, and the 5h strength drops to 72.8MPa, and the freeze-thaw loss doubles; while the nano calcium carbonate + CSH crystal nucleus of the present invention can improve the density and early hydration, and the 5h strength is greater than 78MPa; Comparative Example 7 uses only steel fiber, and the wear resistance decreases (wear value 0.8g / cm 2 ), crack resistance is "poor"; Comparative Example 8 only has PVA fiber, and it was opened to traffic 56 hours after final setting. The 28-day flexural strength plummeted to 16.2MPa; the present invention adopts copper-plated steel fiber + PVA fiber, nanomaterials optimize the microstructure, and composite fibers synergistically enhance toughness and crack resistance.

[0142] The quartz sand and quartz powder used in the present invention are denser and have improved wear resistance compared to the crushed stone + river sand in Comparative Example 1. The water reducer of the present invention is lower and more reasonable than that in Comparative Example 2, avoiding excessive retarding.

[0143] Comparative Example 9 uses a single stirring speed. Although the initial setting time is shortened, the workability is deteriorated. The main reason is that the single stirring speed will cause excessive air entrainment.

[0144] Although the present invention has been described in detail above using general descriptions and specific embodiments, it will be apparent to those skilled in the art that modifications and improvements may be made thereto. Therefore, such modifications and improvements, without departing from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. An early-strength UHPC pavement repair material, characterized in that: The materials include gel materials, aggregates and fiber materials and additives; wherein the gel materials include cement, microsilica powder, nano calcium carbonate, fly ash beads, modified CSH nanocrystals, ultrafine mineral powder and silica microspheres; the aggregates and fiber materials include quartz sand, limestone powder, copper-plated steel fiber, quartz powder, temperature shrinkage fiber, carbon nanotubes and graphene; the additives include retarder, defoamer, water and water reducer.

2. The early-strength UHPC pavement repair material according to claim 1, characterized in that: The cement includes silicate cement and sulphoaluminate cement.

3. The early-strength UHPC pavement repair material according to claim 2, characterized in that: The materials include gel material: 25-35% of silicate cement, 2-10% of sulphoaluminate cement, 3-10% of microsilica powder, 3-8% of fly ash beads, 2-8% of ultrafine mineral powder, 0.1-0.5% of nano calcium carbonate, 1-5% of modified CSH nanocrystals, and 0.1-0.5% of silica microspheres; aggregate and fiber materials: 20-35% of quartz sand, 2-10% of quartz powder, 2-10% of limestone powder, 1.5-2.5% of copper-plated steel fiber, 0.3-0.8% of temperature shrinkage fiber, 0.5-1.5% of carbon nanotubes, and 1-3% of graphene; additives include 0.5-0.8% of water reducer, 0.01-0.05% of retarder, 0.1-0.6% of defoamer, and 7-10% of water.

4. The early-strength UHPC pavement repair material according to claim 2, characterized in that: The water reducer is a polycarboxylic acid high-efficiency water reducer.

5. A method for preparing the early-strength UHPC pavement repair material according to any one of claims 1 to 4, characterized in that: The method comprises: Step 1: Add the gel material into a blender and stir to obtain a preliminary mixed material; Step 2: Add additives to the preliminary mixed material and continue stirring to form a uniform slurry; Step 3: Add aggregate and fiber material to the slurry and continue to stir evenly to obtain early-strength UHPC pavement repair material.

6. The method according to claim 5, characterized in that In the step 1, the stirring time is 1-2 minutes; in the step 2, the stirring time is 3-5 minutes; and in the step 3, the stirring time is 1-3 minutes.

7. A method for repairing a UHPC pavement using the early-strength UHPC pavement repair material according to any one of claims 1 to 4, characterized in that: The method comprises: Step 1: Base surface treatment Use high-pressure water jets to remove loose materials from damaged road surfaces to a solid base layer, forming a rough, clean interface. Clean and dry the base surface. Spray an interface agent on the base surface and pre-embed anchor steel bars in the base surface. Step 2: Material pouring and molding Pouring the bottom repair layer: Pour the early-strength UHPC pavement repair material onto the treated base surface to form the bottom repair layer; before the bottom repair layer begins to set, pour the wear-resistant layer; after defoaming treatment, cover with a water-retaining film and maintain at room temperature.

8. The method according to claim 7, characterized in that In the step 1, the interface agent is a mixture of epoxy resin and silane coupling agent.

9. The method according to claim 8, characterized in that In the step 1, the mass ratio of the epoxy resin to the silane coupling agent is 2.5-3.5:

1.

10. The method according to claim 7, characterized in that In the step 2, the material of the wear-resistant layer is a mixture of early-strength UHPC pavement repair material and 0.3-0.8% corundum.

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