Municipal engineering high-performance rapid repair concrete and construction process thereof

Abstract

The invention discloses municipal engineering high-performance rapid repair concrete and a construction process thereof. By optimizing component design and process adaptation, a solution is provided, and the concrete is composed of 12%-18% of low-alkali Portland cement, 30%-40% of industrial solid waste composite admixture, 35%-42% of recycled aggregate, 2%-3% of low-carbon composite admixture, 8%-11% of water and 1%-3% of function regulator. The matched construction process comprises the steps of base layer treatment, formwork pouring, low-carbon maintenance and rapid open use. The 12h compressive strength of the concrete is greater than or equal to 14MPa, the 24h compressive strength is greater than or equal to 24MPa, the 28d compressive strength reaches the standard, the impermeability grade is greater than or equal to P6, and the interface bonding strength is greater than or equal to The multiple targets of low carbon emission reduction, rapid early strength, high durability and resource recycling are achieved, and the multi-scene repairing requirement is met.

Description

Technical Field

[0001] This invention belongs to the field of municipal engineering technology, specifically relating to a high-performance rapid repair concrete for municipal engineering and its construction process. It is suitable for rapid repair of urban roads, sidewalks, manholes and other facilities after excavation, and is especially suitable for green and efficient repair scenarios such as directional drilling construction pits and pipeline access points. Background Technology

[0002] During trenchless municipal construction, operations such as excavation of working pits and pipeline connection inevitably cause damage to municipal facilities such as roads, sidewalks, and manholes, requiring timely repair to ensure traffic flow and residents' normal lives. However, current traditional repair concrete and construction techniques have many prominent problems: First, carbon emissions remain high. Traditional repair concrete uses a large amount of cement, with carbon emissions exceeding 800 kg per cubic meter of concrete, which is seriously inconsistent with the current requirements for low-carbon development and dual-carbon goals. Secondly, the repair cycle is long, and the early intensity development is slow, usually requiring 7-14 days before traffic can be opened, which causes great disruption to urban traffic efficiency and residents' daily lives during this period. Third, it lacks durability and has poor interfacial bonding performance with old concrete or asphalt structures. After repair, it is prone to quality problems such as cracking and peeling, resulting in a high rework rate and the formation of patched roads and zippered roads. This not only affects the aesthetics of municipal facilities but also increases the later maintenance costs. Fourth, it consumes a lot of resources, does not make full use of industrial waste, and has a low utilization rate of renewable resources such as fly ash, steel slag, and waste concrete, which does not conform to the development concept of green building and resource recycling.

[0003] In response to the repair needs of different parts of municipal engineering projects, such as road surfaces, sidewalks, and manholes, there is an urgent need to develop a repair concrete material and supporting construction technology that combines low carbon emission reduction, rapid early strength, high durability and easy adhesion, and adaptability to multiple scenarios. This will solve the pain points of traditional repair technologies and achieve low-carbon, efficient and high-quality repair of municipal facilities. Summary of the Invention

[0004] The present invention aims to provide a low-carbon, early-strength, high-durability, and easy-to-construct rapid repair concrete and its supporting process to solve the above-mentioned technical problems.

[0005] To address the aforementioned issues, this invention provides a high-performance, rapid-repair concrete for municipal engineering, comprising the following components by mass percentage: Low-alkali silicate cement: 12%-18%; Industrial solid waste composite admixture: 30%-40%, of which fly ash accounts for 20%-25% and steel slag powder accounts for 10%-15%; Recycled aggregate: 35%-42%, particle size 5-20mm; Low-carbon composite admixture: 2%-3%, composed of an early-strength agent, a water-reducing agent, and fibers; the early-strength agent in the low-carbon composite admixture is one or a mixture of several inorganic salt early-strength agents and organic alcohol amine early-strength agents; the water-reducing agent in the low-carbon composite admixture is a polycarboxylate-based water-reducing agent. The inorganic salt early-strength agent is one or more of sodium sulfate, calcium nitrate, sodium nitrate, and sodium thiosulfate; the polycarboxylate-based water-reducing agent is one or more of an esterified copolymer of acrylic acid (AA) / methacrylic acid (MAA) and polyethylene glycol monomethyl ether (MPEG), allyl alcohol polyoxyethylene ether (APEG), methyl allyl alcohol polyoxyethylene ether (HPEG), and isopentenyl alcohol / polyoxyethylene ether (TPEG / IPEG). The key requirements of municipal repair projects are to shorten the curing cycle and quickly open traffic. Traditional concrete has slow early strength development, seriously interfering with urban traffic and residents' lives. The core function of early strength agents is to accelerate the hydration reaction. By promoting the hydration process of cement clinker minerals and water, they can also activate the potential hydration activity of fly ash and steel slag powder in industrial solid waste composite admixtures, thus shortening the strength development cycle. At the same time, they can also make up for the insufficient hydration power caused by low cement content, avoid dragging down early strength, and establish a balance between low carbon and early strength.

[0006] The selection and combined use of water-reducing agents are key to achieving the synergistic effect of low carbon emissions and high performance in this invention. Polycarboxylate-based water-reducing agents have low carbon emissions during their production process and can significantly reduce the amount of water used in concrete. This reduces cement usage and avoids increased structural porosity caused by high water consumption, indirectly improving durability and reducing secondary carbon emissions from later repairs. This invention uses high amounts of industrial solid waste and recycled aggregates. These components have rough surfaces and high water absorption, which can easily lead to poor concrete fluidity and pouring difficulties. The water-reducing agent can disperse cement particles and reduce interparticle attraction, stabilizing the concrete slump at 120-180mm, ensuring compaction during pouring and preventing insufficient strength or cracks due to construction defects. The low water-cement ratio combined with the dispersing effect of the water-reducing agent can reduce capillary porosity inside the concrete, improve density, and enhance impermeability.

[0007] The fibers can be one or more of the following: polypropylene (PP) fibers, polyvinyl alcohol (PVA) fibers, polyester (PET) fibers, polyethylene (PE) fibers, cellulose fibers, basalt fibers, and glass fibers. The fibers are uniformly dispersed within the concrete. When microcracks develop in the concrete due to hydration heat and shrinkage, the fibers can transfer stress through bridging, preventing crack propagation and transforming macroscopic cracks into microscopic cracks. This avoids structural damage caused by crack penetration. The fibers can penetrate deep into the roughened pores of the old concrete / asphalt interface, forming a dual bonding effect of mechanical interlocking and fiber bridging, further enhancing the interfacial bond strength. The addition of fibers does not affect the hydration acceleration effect of the early-strength agent, nor does it conflict with the dispersion effect of the water-reducing agent. Simultaneously, it can improve the wear resistance of road surfaces and the flexural strength of sidewalks, ensuring structural stability in different repair scenarios.

[0008] The low-carbon composite admixture contains an accelerator, water-reducing agent, and fiber in a mass ratio of 5:4:1, with the accelerator accounting for 50%. This high proportion (50%) effectively promotes the hydration reaction of cement clinker minerals (C3S, C3A) with water, while simultaneously activating the potential hydration activity of industrial solid wastes such as fly ash and steel slag powder. This compensates for insufficient hydration motives caused by low cement content, ensuring rapid achievement of early strength standards. For concrete formulations with high industrial solid waste content, the high proportion of the accelerator balances the contradiction between low-carbon cement reduction and ensuring early strength and timely aging, avoiding early strength lag due to cement reduction, and preventing hydration heat concentration due to excessive amounts. The 40% water-reducing agent content matches the raw material characteristics of concrete, namely high admixture of recycled aggregate and industrial solid waste, and supports the synergistic achievement of low carbon and high performance. Concrete containing 35%-42% recycled aggregate, with its rough surface and high water absorption, along with 30%-40% industrial solid waste admixtures, easily leads to poor concrete fluidity and rapid slump loss. A 40% polycarboxylate-based low-carbon water-reducing agent can efficiently disperse cement and solid waste particles, reduce interparticle attraction, and stably control the concrete slump within a reasonable range. This ensures compaction during pouring and prevents insufficient strength or increased porosity due to construction defects. The 40% proportion guarantees effective dispersion without causing retardation due to excessive water-reducing agent. When used in conjunction with a 50% accelerator, it can precisely control the initial setting time of concrete (2-4 hours) and the final setting time (4-6 hours), without compromising the core objective of rapid traffic opening. Accelerators that accelerate hydration can increase early shrinkage of concrete, while the high solid waste content in the low-carbon formula can reduce concrete toughness, making it prone to cracking and spalling. A 10% fiber content, such as polypropylene or polyester fiber, when evenly dispersed, can form a three-dimensional bridging network. When microcracks appear in the concrete, the fibers can transfer stress, prevent crack propagation, and transform macro-cracks into micro-cracks, avoiding structural damage caused by crack penetration. The fibers can penetrate deep into the roughened pores of the old concrete / asphalt interface, forming a dual bonding effect of mechanical interlocking and fiber bridging, further improving the interfacial bond strength. The 10% content ensures crack resistance without causing excessive fiber entanglement, preventing a decrease in concrete slump or an increase in internal porosity. This ensures uniform mixing and compaction during wet mixing, without affecting compressive strength and impermeability.

[0009] Water: 8%-11%; Functional regulator: 1%-3%.

[0010] Furthermore, the recycled aggregate is waste concrete that has been crushed, washed, and dried, with a moisture content of ≤3%. The strength and workability of concrete depend on the effective water-cement ratio, i.e., the ratio of water to cementitious materials such as cement. If the recycled aggregate contains excessive adhering water and internal pore water, it will be uncontrollably released into the mixture during mixing, effectively increasing the effective water-cement ratio and leading to a decrease in strength. The purpose of a moisture content of ≤3% is to dry the recycled aggregate to a low-moisture state, bringing it close to or reaching a saturated surface-dry state. This allows it to be treated as dry aggregate during mix design, thereby accurately calculating and controlling the amount of added water, ensuring a stable water-cement ratio, which is the foundation for achieving early strength and high strength in the formula.

[0011] Furthermore, the early-strength agent in the low-carbon composite admixture is one or a mixture of several of inorganic salt early-strength agents and organic alcohol amine early-strength agents, and the water-reducing agent in the low-carbon composite admixture is a polycarboxylate water-reducing agent.

[0012] Furthermore, the inorganic salt early strength agent is one or more of sodium sulfate, calcium nitrate, sodium nitrate, and sodium thiosulfate; the polycarboxylic acid water-reducing agent is one or more of the esterified copolymer of acrylic acid (AA) / methacrylic acid (MAA) and polyethylene glycol monomethyl ether (MPEG), allyl alcohol polyoxyethylene ether (APEG), methyl allyl alcohol polyoxyethylene ether (HPEG), and isopentenyl alcohol polyoxyethylene ether (TPEG / IPEG).

[0013] Furthermore, the functional modifier is selected as either abrasion-resistant agent or permeability modifier according to the application scenario. The functional modifier is abrasion-resistant agent when used for road surface repair, and a permeability modifier when used for sidewalk or manhole repair. The abrasion-resistant agent can be one or more of the following: quartz sand, corundum, corundum powder, iron ore sand, copper slag, nickel-iron slag, and silicon carbide waste. The permeability modifier can be one or more of the following: silica fume, phosphorus slag powder, metakaolin, acrylic copolymer emulsion, and styrene-acrylic emulsion.

[0014] On the other hand, a construction process for the aforementioned high-performance rapid repair concrete for municipal engineering is also provided, including the following steps: Substrate preparation: Clean the repair area, roughen the old concrete or asphalt interface, apply an environmentally friendly interface treatment agent, and let it stand until it is surface dry; Formwork erection and pouring: Erect quick-release formwork, pour concrete and vibrate to compact it, and smooth and polish the surface; Low-carbon maintenance: Cover with a moisturizing maintenance film, spray with an eco-friendly maintenance agent, and choose natural maintenance or electric heat tracing maintenance according to the ambient temperature; Open for use: Non-motorized vehicles can pass 8-20 hours after road surface maintenance, and motorized vehicles can pass 18-30 hours later; sidewalks and inspection wells can be put into use 20-30 hours after maintenance.

[0015] Furthermore, in the aforementioned base treatment, the interface treatment agent is left to stand for 20-40 minutes after application.

[0016] Furthermore, in the aforementioned low-carbon maintenance, electric heat tracing is used when the ambient temperature is below 10°C.

[0017] Furthermore, the initial setting time of the concrete is 2-4 hours, and the final setting time is 4-6 hours.

[0018] Furthermore, after construction is completed, a quality acceptance test is required, including flatness testing and 28-day compressive strength and impermeability grade testing. The flatness deviation should not exceed 4mm, and the impermeability grade should not be lower than P6.

[0019] The beneficial effects of this invention are: (1) Through optimized component design, the amount of low-alkali silicate cement used is significantly reduced. At the same time, a high proportion of industrial solid waste composite admixtures and recycled aggregates are added to reduce the carbon emissions per cubic meter of concrete. The selection of polycarboxylate superplasticizer further reduces carbon emissions during production and use, and a large amount of industrial waste is disposed of, reducing resource waste and environmental burden, which is in line with the concept of green building and low-carbon development.

[0020] (2) Relying on the optimized ratio of early-strength agent: water-reducing agent: fiber = 5:4:1 in the low-carbon composite admixture, and the dual activation effect of the early-strength agent on cement hydration and industrial solid waste activity, the early strength of concrete develops rapidly. The compressive strength at 12 hours is ≥14MPa, the compressive strength at 24 hours is ≥24MPa, and the compressive strength at 3 days is ≥35MPa, far exceeding the performance of traditional repair concrete. After construction, the repair cycle is shortened, the interference with urban traffic and residents' lives is greatly reduced, and the urgent need for rapid restoration of municipal engineering functions is met.

[0021] (3) The internal structure of the concrete is optimized by water-reducing agent and reinforced by fiber to form a dense and stable structural system. The compressive strength after 28 days is up to 48.5MPa, the impermeability grade is ≥P6, and the bonding strength with the old concrete / asphalt interface is ≥2.9MPa. This effectively solves the pain points of separation, cracking and peeling of new and old structures in traditional repair projects. The repair rate during the warranty period is ≤1%, completely eliminating the phenomenon of patched roads and zippered roads, significantly extending the service life of municipal facilities and reducing the economic cost of later maintenance and repair.

[0022] (4) The formula of this invention maximizes the resource utilization of industrial waste and construction solid waste. The total utilization rate of industrial solid waste such as fly ash and steel slag powder and recycled aggregates of waste concrete exceeds 65%. This not only reduces the environmental pressure caused by waste landfill and stockpiling, but also reduces the mining and production consumption of natural aggregates and cement. While saving natural resources, it also reduces the cost of raw material procurement, achieving a dual unity of environmental and economic benefits.

[0023] (5) The concrete preparation process is simple, and no special equipment is required for raw material pretreatment and mixing. The slump can be stably controlled at 120-180mm, which is suitable for different pouring needs. During construction, quick-release formwork and targeted vibration are used, and the base treatment and curing process is convenient and efficient. The low-carbon curing solution reduces energy consumption compared with traditional steam curing and does not require complicated equipment. It can be directly adapted to the existing municipal repair construction system, reducing the construction threshold and energy consumption costs.

[0024] (6) By selecting functional modifiers according to specific scenarios, wear-resistant agents such as quartz sand and copper slag powder are compounded for road surfaces to improve wear resistance; permeability modifiers such as silica fume and acrylic copolymer emulsion are compounded for sidewalks / inspection wells to ensure a balance between permeability and strength. Combined with the gradation of recycled aggregates and the appropriate adjustment of admixtures, concrete can flexibly meet the repair needs of different parts such as road surfaces, sidewalks, inspection wells, and directional drilling pits, taking into account the differentiated properties such as strength, wear resistance, permeability, and decoration. It has strong versatility and specificity and a wide range of applications. Detailed Implementation

[0025] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can more clearly understand the present invention. The following embodiments are only used to illustrate the present invention and are not intended to limit the scope of protection of the present invention.

[0026] Example 1: Road Surface Repair Concrete formula, by weight percentage: Low-alkali silicate cement: 16%; Industrial solid waste composite admixture: 32%, of which fly ash 22% and steel slag powder 10%; Recycled aggregate: 38%, obtained from the crushing and processing of waste concrete, with a moisture content of 2.5% and a particle size of 5-15mm continuous gradation; Low-carbon composite admixture: 2.5%, of which early strength agent: water reducing agent: fiber = 5:4:1, wherein the early strength agent is a compound of sodium sulfate and triethanolamine, the water reducing agent is HPEG type polycarboxylate water reducing agent, and the fiber is 12mm long polypropylene monofilament fiber; Functional modifier: 2.5%, selected wear-resistant agent, which is a compound of 100-mesh quartz sand and copper slag powder; Water: 9%.

[0027] Preparation process: Pass the recycled aggregate and industrial solid waste composite admixture through a 100-mesh sieve; add dry materials according to the ratio and stir for 2.5 minutes, then add water and admixtures and stir for 4.5 minutes, controlling the slump to 135mm; test the spread to meet the requirements, the initial setting time is 3 hours, and the final setting time is 5 hours. Construction process: Clean up debris on the road surface, roughen the old concrete interface, apply interface treatment agent and let it stand for 30 minutes; set up quick-release formwork, use vibrator to vibrate and pour, and smooth and polish the surface; at an ambient temperature of 15℃, use a moisturizing curing film and an ecological curing agent for natural curing. Example 2: Sidewalk Repair Concrete formula, by weight percentage: Low-alkali silicate cement: 14%; Industrial solid waste composite admixture: 36%, of which fly ash 24% and steel slag powder 12%; Recycled aggregate: 40%, obtained from the crushing and processing of waste concrete, with a moisture content of 2.2% and a single gradation of 5-10mm particle size; Low-carbon composite additive: 2.2%, same ratio as in Example 1, but the fiber is replaced with 18mm long cellulose fiber; Functional regulator: 1.8%, using a water-permeable regulator, which is a compound of silica fume and acrylate copolymer emulsion; Water: 10%.

[0028] Preparation process: The moisture content of recycled aggregate was tested, and the industrial solid waste composite admixture was passed through a 100-mesh sieve; the dry material was stirred for 2 minutes, water and admixtures were added and stirred for 4 minutes, and the slump was controlled at 165 mm; the initial setting time was 2.5 hours, and the final setting time was 4.5 hours. Construction process: Clean the sidewalk debris, roughen the old asphalt interface, and apply an interface treatment agent; after setting up the formwork, use a plate vibrator to vibrate and pour the asphalt, and smooth it; ambient temperature 12℃, natural curing.

[0029] Comparative Example 1 Formula: Based on Example 1, the composite admixture is removed, and only an equal amount of 2.5% sodium sulfate early strength agent is added. The fiber and high-efficiency water-reducing agent are also removed.

[0030] Comparative Example 2 Formula: The solid waste dosage is the same as in Example 1, but low-carbon composite additives are not used; only ordinary water-reducing agents are used.

[0031] Comparative Example 3 Formula: Basically the same as in Example 1, but the recycled aggregate is simply crushed, not washed or dried, and has a moisture content of about 8%.

[0032] Comparative Example 4 Formula: Basically the same as in Example 1, but the ratio of early strength agent: water reducing agent: fiber in the low-carbon composite admixture is 3:3:4.

[0033] Experimental Data and Analysis:

[0034] Experimental data analysis 1. Rapid early strength performance analysis Example 1 demonstrated optimal early strength, with a strength of 18.3 MPa at 12 hours and 29.7 MPa at 24 hours. This was attributed to the strong activating effect of the high proportion of sodium sulfate combined with triethanolamine in the 5:4:1 composite admixture, as well as the low water-to-binder ratio and dense environment created by the HPEG water-reducing agent.

[0035] In Comparative Example 1, the 12-hour strength using only sodium sulfate was 12.1 MPa, which barely met the standard, but the 24-hour strength was only 18.5 MPa, which was significantly lower, and the strength in the later stage was reduced, indicating that a single early strength agent cannot achieve continuous and balanced early strength and high strength.

[0036] In Comparative Example 2, which did not contain any composite additives, the strength in the first 12 hours was only 5.8 MPa. This demonstrates that even if the amount of solid waste added is the same as in Example 1, without the activation of the composite early strength agent, the early activity of industrial solid waste cannot be exerted, and the goal of rapid remediation cannot be achieved.

[0037] In Comparative Example 4, the ratio of components in the composite admixture was 3:3:4. Its early strength at 12 hours was 14.5 MPa, significantly lower than that of Example 1. This indicates that reducing the proportion of early strength agent and water-reducing agent and increasing the fiber proportion weakened the chemical activation and water-reducing compaction effects, resulting in insufficient momentum for early strength development.

[0038] The 28-day strengths of Examples 1 and 2 were 48.5 MPa and 41.2 MPa, respectively, and their impermeability grades were P10 and P8, respectively, both far exceeding the design requirements. This is attributed to the low water-cement ratio and high density brought about by the polycarboxylate superplasticizer. The crack-resistant and toughening effects of the fibers elevated the impermeability performance to a high level. The pretreatment of the recycled aggregate (moisture content ≤3%) ensured a stable water-cement ratio and a clean interface. In Comparative Example 3, untreated aggregate was used, resulting in a significantly reduced 28-day strength of only 40.1 MPa and an interfacial bond strength of only 2.0 MPa. This indicates that the high moisture content and mud content of unwashed and undried recycled aggregate deteriorate the concrete matrix and interfacial transition zone, severely affecting long-term durability.

[0039] The excellent interfacial bond strengths of Examples 1 and 2 (3.1 MPa and 2.9 MPa respectively) are attributed to the good mechanical interlocking between the clean, dry recycled aggregate and the old / new interface, as well as the bridging and reinforcing effect of the fibers in the interfacial region. Comparative Example 1, using a single early-strength agent, suffered from poor workability and easy bleeding, leading to inadequate compaction and interfacial defects, resulting in the lowest bond strength. Comparative Example 4, with its excessively high fiber content, was prone to fiber clumping during mixing, affecting the homogeneity and surface smoothness of the concrete, resulting in slightly poorer smoothness. This demonstrates that the 5:4:1 ratio provides an optimized balance between toughening effect and workability.

[0040] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A high-performance, rapid-repair concrete for municipal engineering, characterized in that, The components include the following percentages by mass: Low-alkali silicate cement: 12%-18%; Industrial solid waste composite admixture: 30%-40%, of which fly ash accounts for 20%-25% and steel slag powder accounts for 10%-15%; Recycled aggregate: 35%-42%, particle size 5-20mm; Low-carbon composite admixture: 2%-3%, wherein the low-carbon composite admixture is composed of early strength agent, water reducing agent and fiber; Water: 8%-11%; Functional regulator: 1%-3%.

2. The concrete according to claim 1, characterized in that, The recycled aggregate is waste concrete that has been crushed, washed, and dried, with a moisture content of ≤3%.

3. The concrete according to claim 1, characterized in that, The mass ratio of early-strength agent, water-reducing agent, and fiber in the low-carbon composite admixture is 5:4:1; the early-strength agent in the low-carbon composite admixture is one or a mixture of several of inorganic salt early-strength agents and organic alcohol amine early-strength agents; and the water-reducing agent in the low-carbon composite admixture is a polycarboxylate water-reducing agent.

4. The concrete according to claim 1, characterized in that, The functional modifier is selected as either a wear-resistant agent or a permeability modifier depending on the application scenario. When used for road surface repair, the functional modifier is a wear-resistant agent, and when used for sidewalk or manhole repair, it is a permeability modifier.

5. The concrete according to claim 3, characterized in that, The inorganic salt early strength agent is one or more of sodium sulfate, calcium nitrate, sodium nitrate, and sodium thiosulfate; the polycarboxylic acid water-reducing agent is one or more of the esterified copolymer of acrylic acid / methacrylic acid and polyethylene glycol monomethyl ether, allyl alcohol polyoxyethylene ether, methyl allyl alcohol polyoxyethylene ether, and isopentenol / polyoxyethylene ether.

6. A construction process for high-performance rapid repair concrete for municipal engineering as described in any one of claims 1-5, characterized in that, Includes the following steps: Substrate preparation: Clean the repair area, roughen the old concrete or asphalt interface, apply an environmentally friendly interface treatment agent, and let it stand until it is dry to the touch; Formwork erection and pouring: Erect quick-release formwork, pour concrete and vibrate to compact it, and smooth and polish the surface; Low-carbon maintenance: Cover with a moisturizing maintenance film, spray with an eco-friendly maintenance agent, and choose natural maintenance or electric heat tracing maintenance according to the ambient temperature; Open for use: Non-motorized vehicles can pass 8-20 hours after road surface maintenance, and motorized vehicles can pass 18-30 hours later; sidewalks and inspection wells can be put into use 20-30 hours after maintenance.

7. The construction process according to claim 6, characterized in that, In the aforementioned base treatment, the interface treatment agent is left to stand for 20-40 minutes after application.

8. The construction process according to claim 6, characterized in that, In the aforementioned low-carbon maintenance, electric heat tracing is used when the ambient temperature is below 10℃.

9. The construction process according to claim 6, characterized in that, The initial setting time of the concrete is 2-4 hours, and the final setting time is 4-6 hours.

10. The construction process according to claim 6, characterized in that, After construction is completed, a quality acceptance test is required, including flatness testing and 28-day compressive strength and impermeability grade testing. The flatness deviation should not exceed 4mm, and the impermeability grade should not be lower than P6.

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