A construction method for high crack resistance and long durability concrete structures

Abstract

This invention discloses a construction method for a high crack-resistant and long-durability concrete structure, relating to the field of concrete structure construction technology. The method includes dividing the structure into a main pouring zone, a constraint transition zone, and a surface protection zone based on the constraint and exposed surface locations; preparing main concrete containing composite expansion components and crack-resistant fibers, and interlayer compensation material containing delayed expansion components, internal curing particles, and fiber dispersion slurry; continuously pouring the main concrete in layers, and placing the interlayer compensation material between adjacent pouring layers and in the constraint transition zone; adjusting the insulation and moisture retention curing according to the temperature difference between the core and the surface and the surface humidity; constructing a penetrating crystalline protective slurry layer and maintaining moisture retention after the surface reaches a preset capillary water absorption state; improving the crack resistance, impermeability, and long-term durability of the concrete structure by reducing interlayer microcracks and constraint cracks; and solving the problems of shrinkage compensation in high-risk crack areas of existing concrete structures, and the easy formation of microcracks and weak penetration channels at interlayer interfaces.

Description

Technical Field

[0001] This invention relates to the field of concrete structure construction technology, and in particular to a construction method for high crack resistance and long durability concrete structures, applicable to the construction of underground, underwater, foundation, pipe gallery, pile cap, basement floor slab and basement exterior walls and other concrete structures with obvious constraints and high durability requirements. Background Technology

[0002] Underground or foundation-type concrete structures are often simultaneously affected by factors such as heat of hydration, drying shrinkage, external boundary constraints, groundwater erosion, chloride ion penetration, and freeze-thaw cycles during construction and service. If the internal temperature gradient is too large in the early stages of hardening, tensile stress concentration can easily form on the surface or near the constraint boundaries. During the subsequent drying process, if the rate of water loss from the surface exceeds the rate of internal moisture migration, drying shrinkage cracks are likely to occur. Once cracks form, corrosive media such as moisture, chloride ions, and sulfates can enter the structure through the cracks and capillary channels, further reducing the structure's durability.

[0003] Existing technologies include methods to improve the crack resistance of concrete by incorporating expanding agents, polypropylene fibers, and mineral admixtures. Other methods employ segmented pouring, temperature-controlled curing, and covering with moisture-retaining agents or coating the surface with cement-based penetrating crystalline materials. While these methods can improve the crack resistance, waterproofing, and impermeability of concrete to some extent, they still have the following shortcomings: First, existing solutions often incorporate expansion agents and fibers into concrete as a whole, without providing differentiated stress compensation for high-risk crack areas such as joint surfaces, corners, formwork sidewalls, and areas with dense reinforcement. This can easily lead to an increase in the overall material content but insufficient crack resistance in certain areas.

[0004] Second, existing layered pouring methods usually focus on pouring thickness, pouring sequence and temperature control measures, and rarely set up compensation interfaces that can work in conjunction with the upper and lower concrete layers to address the early shrinkage differences between adjacent pouring layers. This may result in the formation of microcracks or weak penetration channels at the interlayer interfaces.

[0005] Third, existing surface waterproofing layers are mostly applied directly after concrete demolding or after it has reached a certain age, without fully considering the impact of concrete surface moisture content and capillary water absorption on the depth of penetration and crystallization reaction. This can easily lead to problems such as the surface being too dry, resulting in insufficient penetration of active components, or the surface being too wet, resulting in unstable adhesion of the slurry layer.

[0006] Fourth, existing maintenance control is mostly based on a single temperature difference or maintenance age, without linking core temperature, surface humidity, temperature drop rate and the timing of surface protection construction window, making it difficult to form a continuous construction closed loop between crack resistance and durability protection.

[0007] In summary, the existing technology has at least the following technical problems: it is difficult to carry out differentiated shrinkage compensation for high-risk crack areas during the hardening and curing process of concrete structures; microcracks and weak penetration channels are easily formed at the interlayer interface; and the timing of surface durability protection construction is not well matched with the capillary water absorption state of concrete. Based on these issues, there is still room for improvement in the crack resistance and long-term durability of concrete structures. Summary of the Invention

[0008] The purpose of this invention is to provide a construction method for high crack resistance and long durability concrete structures. By setting up risk-restrained zones, interlayer compensation materials, continuous pouring windows, temperature and humidity coordinated curing, and capillary-activated surface protection steps during the construction process of concrete structures, the concrete structure can have better crack resistance and durability in the early hardening, interlayer bonding, surface protection, and long-term service stages. This solves the problems of existing concrete structures, such as difficulty in differentiated shrinkage compensation for high-risk crack areas during hardening and curing, easy formation of microcracks and weak penetration channels at the interlayer interface, and insufficient matching between the timing of surface durability protection construction and the capillary water absorption state of concrete.

[0009] The preferred technical solutions among the many technical solutions provided by this invention can produce a variety of technical effects, which are described in detail below.

[0010] To solve the above-mentioned technical problems, the present invention provides the following technical solution: a construction method for a high crack resistance and long durability concrete structure, comprising the following steps: S1, dividing the area to be constructed into a main pouring area, a constraint transition area and a surface protection area according to the thickness of the concrete structure to be constructed, the location of the boundary constraint and the location of the exposed surface; S2. Prepare the main concrete and interlayer compensation material, wherein the main concrete contains a composite expansion component and crack-resistant fibers, and the interlayer compensation material contains a delayed expansion component, internal curing particles and fiber dispersion paste; S3. The main concrete is poured in a layered continuous pouring manner. Interlayer compensation material is placed between two adjacent layers of main concrete and in the constrained transition zone. The interlayer compensation material is vibrated and compacted with the adjacent upper and lower layers of main concrete. S4. Collect temperature and humidity data in the core of the poured concrete, at a distance of 30mm to 80mm from the surface, and in the constrained transition zone. Adjust the covering, moisturizing, spraying, and heat preservation measures according to the temperature difference between the core and the surface and the surface humidity. S5. After the concrete surface reaches the preset capillary water absorption state, the surface protection area is moistened and cleaned, and a penetrating crystalline protective slurry layer is applied. S6. Moisturize and cure the concrete surface with the penetrating crystalline protective slurry layer during construction, and wait for the penetrating crystalline protective slurry layer to bond with the concrete surface to form a bonded protective layer.

[0011] As one optional implementation, in S1, the main pouring area is the concrete pouring area other than the constraint transition area and the surface protection area; the constraint transition area includes the location near the existing concrete joint surface, construction joint, corner, dense reinforcement area, formwork sidewall or foundation constraint boundary; the surface protection area is the area 0mm to 20mm away from the exposed concrete surface.

[0012] As one optional implementation, the main concrete, per cubic meter, comprises: 250kg-360kg of cement, 80kg-180kg of mineral admixtures, 650kg-850kg of fine aggregate, 950kg-1150kg of coarse aggregate, 130kg-170kg of water, 4kg-9kg of water-reducing agent, 18kg-38kg of composite expansion component, and 0.6kg-2.2kg of crack-resistant fiber; the mineral admixtures include at least two of fly ash, granulated blast furnace slag powder, and silica fume; the fine aggregate is medium sand; the coarse aggregate is continuously graded crushed stone; and the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

[0013] In one optional embodiment, the composite expansion component includes calcium oxide expanded clinker, lightly calcined magnesium oxide, and calcium sulfoaluminate expanded component, with a mass ratio of 1:(0.25-0.65):(0.35-0.85); the crack-resistant fiber includes at least two of polyvinyl alcohol fiber, polypropylene fiber, and basalt fiber.

[0014] As one optional implementation, the interlayer compensation material comprises, by weight: 100 parts cement, 20 to 60 parts mineral admixture, 8 to 18 parts delayed expansion component, 3 to 12 parts internal curing particles, 2 to 8 parts fiber dispersion paste, 0.8 to 2.5 parts water-reducing agent, and 35 to 55 parts water; the internal curing particles are pre-wetted lightweight porous particles or water-absorbing resin particles.

[0015] As one optional implementation, the mineral admixture in the interlayer compensation material includes at least two of granulated blast furnace slag powder, fly ash, and silica fume; the retarded expansion component includes lightly calcined magnesium oxide, calcium sulfoaluminate expansion component, and gypsum sulfate component; the water-reducing agent is a polycarboxylate-based water-reducing agent; and the internal curing particles include at least one of pre-wetted lightweight porous ceramsite powder and water-absorbing resin particles.

[0016] As one optional implementation, in S3, the pouring thickness of each layer of the main concrete is 250mm to 500mm; after the lower layer of main concrete has been vibrated and compacted, when its surface penetration resistance reaches 0.2MPa to 0.8MPa, the interlayer compensation material is laid; the thickness of the interlayer compensation material is 5mm to 25mm, and the interlayer compensation material is made to penetrate into the interface depth of the adjacent main concrete to 10mm to 40mm through secondary vibration.

[0017] As one alternative implementation, in S4, when the temperature difference between the core and surface of the poured concrete is greater than 18°C, an insulation covering layer is added; when the relative humidity of the surface of the poured concrete is less than 80%, spraying is performed to replenish moisture; when the temperature drop rate of the core of the poured concrete is greater than 1.5°C / h, the insulation covering time is extended.

[0018] As one optional implementation, in S5, the preset capillary water absorption state is: the moisture content of the concrete surface layer is 8% to 16%, and the capillary water absorption rate of the surface layer in 10 minutes is 0.05 kg / m³. 2 ~0.30kg / m 2 After reaching the preset capillary water absorption state, the penetrating crystalline protective slurry layer is scraped or sprayed onto the concrete surface.

[0019] In one optional embodiment, the penetrating crystalline protective slurry layer comprises, by weight: 100 parts silicate cement, 35-80 parts quartz sand, 5-18 parts silicate active component, 2-8 parts calcium salt activating component, 0.1-1.2 parts penetrating aid, 0.2-1.5 parts water-retaining and thickening component, and 35-60 parts water; the silicate active component includes at least one of powdered sodium silicate, powdered potassium silicate, and metakaolin; the calcium salt activating component includes at least one of calcium formate, calcium nitrate, and calcium hydroxide; the penetrating aid includes at least one of polycarboxylate dispersant and silane coupling agent; and the water-retaining and thickening component includes at least one of cellulose ether, starch ether, and bentonite.

[0020] Compared with the prior art, the present invention has the following beneficial effects: This invention divides the concrete structure into a main pouring zone, a constraint transition zone, and a surface protection zone based on boundary constraints and exposed surface locations before construction. It also lays an interlayer compensation material containing delayed expansion components, internal curing particles, and fiber dispersion slurry at high-risk crack locations. This concentrates the shrinkage compensation effect on locations prone to tensile stress and microcracks. Compared to existing technologies that simply increase the overall dosage of expansion agent or fiber, this invention provides a more targeted improvement for locations prone to tensile stress and microcracks.

[0021] This invention sets interlayer compensation material between adjacent main concrete layers, and judges and controls the timing of the placement window by the penetration resistance, so that the interlayer compensation material is vibrated and combined with the upper and lower main concrete layers, reducing the interface micro-cracks and weak penetration channels caused by the difference in hydration, water loss and shrinkage between the upper and lower layers.

[0022] Furthermore, by jointly adjusting the core temperature, surface temperature, surface humidity, and core temperature drop rate, the required covering, moisturizing, spraying, and heat preservation measures for the poured concrete are adjusted, so that the early temperature shrinkage and drying shrinkage of the concrete can be controlled, avoiding the insufficient curing caused by the existing technology that only uses the number of curing days or a single temperature difference as the basis for curing.

[0023] Furthermore, a penetrating crystalline protective slurry layer is applied after the concrete surface reaches a preset capillary water absorption state, allowing the active components in the protective slurry layer to migrate and react into the capillary pores of the concrete surface under suitable water content conditions, thereby improving the surface impermeability, chloride ion intrusion resistance, and freeze-thaw durability.

[0024] Finally, the present invention forms a continuous construction process consisting of material modification, interlayer stress compensation, temperature and humidity synergistic curing, and capillary activated surface protection. Compared with the existing technologies that use crack-resistant agents alone, extend the curing time alone, or apply waterproof layers alone, this method is more suitable for underground and foundation concrete structures that are subject to significant constraints and have high durability requirements. Attached Figure Description

[0025] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of the construction method of the present invention; Figure 2 This is a schematic diagram of the partitioning of a slab concrete structure. Figure 3 This is a schematic diagram showing the layout of interlayer compensation material between adjacent main concrete layers. Figure 4 This is a schematic diagram of the structure for bonding a penetrating crystalline protective grout layer to the concrete surface.

[0027] The accompanying figure is labeled as follows: 1. Concrete structure; 11. Main pouring area; 12. Constrained transition area; 13. Surface protection area; 2. Main concrete; 3. Interlayer compensation material; 4. Vibrating rod; 5. Penetrating crystalline protective slurry layer; 6. Combine with protective layer. Detailed Implementation

[0028] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings.

[0029] The specific implementation provides a construction method for a high crack-resistant and long-durability concrete structure, including: dividing the structure into a main pouring zone, a constraint transition zone, and a surface protection zone according to the constraint location and exposed surface location; preparing main concrete containing composite expansion components and crack-resistant fibers, and interlayer compensation material containing delayed expansion components, internal curing particles, and fiber dispersion slurry; continuously pouring the main concrete in layers, and placing interlayer compensation material between adjacent pouring layers and in the constraint transition zone; adjusting the heat preservation and moisture retention curing according to the temperature difference between the core and the surface and the surface humidity; constructing a penetrating crystalline protective slurry layer and maintaining moisture retention after the surface reaches a preset capillary water absorption state; improving the crack resistance, impermeability, and long-term durability of the concrete structure by reducing interlayer microcracks and constraint cracks; effectively solving the problems of existing concrete structures having difficulty in differentiated shrinkage compensation for high-risk crack areas during hardening and curing, easy formation of microcracks and weak penetration channels at the interlayer interface, and insufficient matching between the timing of surface durability protection construction and the capillary water absorption state of the concrete.

[0030] Example 1 This embodiment provides a construction method for a high crack-resistant and long-lasting durable concrete structure 1, such as... Figures 1 to 4 As shown, the concrete structure 1 in this embodiment is the base slab structure of the underground utility tunnel. The base slab is 800mm thick, the concrete design strength grade is C40, the design impermeability grade is not lower than P8, and the construction environment temperature is 18℃~32℃.

[0031] Before construction, based on the thickness, boundary constraint location, and exposed surface location of the concrete structure 1 to be constructed, the area to be constructed is divided into the main pouring area 11, the constraint transition area 12, and the surface protection area 13. Among them, the area within 300mm to 500mm of the existing concrete joint surface, construction joint, corner, dense reinforcement area, formwork sidewall, and foundation constraint boundary is designated as the constraint transition area 12; the area within 0mm to 20mm of the exposed concrete surface is designated as the surface protection area 13; and the area other than the constraint transition area 12 and the surface protection area 13 is designated as the main pouring area 11.

[0032] The main concrete 2, per cubic meter, includes: 300 kg of ordinary Portland cement, 130 kg of mineral admixtures, 750 kg of fine aggregate, 1040 kg of coarse aggregate, 150 kg of water, 6.5 kg of water-reducing agent, 28 kg of composite expansion component, and 1.4 kg of crack-resistant fiber.

[0033] The mineral admixture is a composite admixture of secondary fly ash, S95 grade granulated blast furnace slag powder, and silica fume, with a mass ratio of 5:7:1; the fine aggregate is medium sand from Zone II, with a fineness modulus of 2.5 to 2.8 and a mud content of no more than 2.0%; the coarse aggregate is 5mm to 25mm continuously graded crushed stone, made of limestone or basalt, with a needle-like or flaky particle content of no more than 8%; and the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent (HPWR, conforming to the mandatory national standard GB8076), with a water reduction rate of no less than 25%.

[0034] The crack-resistant fiber is a composite fiber of polyvinyl alcohol (PVA) fiber, polypropylene (PP) fiber, and basalt fiber. The PVA fiber has a length of 6mm–12mm and a diameter of 12μm–20μm; the PP fiber has a length of 9mm–18mm; and the basalt fiber has a length of 6mm–12mm. The mass ratio of the three fibers is 5:3:2. The PVA fiber improves the slurry bridging ability, the PP fiber reduces early plastic shrinkage microcracks, and the basalt fiber improves the tensile strength of the interface after hardening.

[0035] The composite expansion component includes calcium oxide expanded clinker, lightly calcined magnesia, and calcium sulfoaluminate expanded components, with a mass ratio of 1:0.45:0.60. Specifically, the calcium oxide expanded clinker is a free calcium oxide type expanded clinker formed by calcining and grinding limestone raw materials, requiring a free calcium oxide content of 55%–75%; the lightly calcined magnesia is active magnesia powder formed by lightly calcining magnesite at 850℃–1000℃ and then grinding, requiring an MgO content of not less than 80% and an activity index of 60s–80s; the calcium sulfoaluminate expanded component is sulfoaluminate clinker powder containing anhydrous calcium sulfoaluminate mineral phase, combined with anhydrite or natural gypsum as a sulfate source.

[0036] The interlayer compensation material 3, by weight, includes: 100 parts cement, 40 parts mineral admixture, 12 parts delayed expansion component, 8 parts internal curing granules, 5 parts fiber dispersion paste, 1.5 parts water-reducing agent, and 45 parts water.

[0037] The cement in interlayer compensation material 3 is ordinary Portland cement; the mineral admixture is a mixture of S95 grade granulated blast furnace slag powder, secondary fly ash, and silica fume, with a mass ratio of 5:3:1; the delayed expansion component is a mixture of lightly calcined magnesium oxide, calcium sulfoaluminate expansion component, and anhydrite, with a mass ratio of 7:4:1; the water-reducing agent is polycarboxylate powder water-reducing agent (PCE) or liquid polycarboxylate high-performance water-reducing agent; the internal curing particles are a composition of pre-wetted lightweight porous ceramsite powder and water-absorbing resin particles, with a mass ratio of 7:1, and the water-absorbing resin particles are acrylate-acrylamide copolymer water-absorbing resin particles. The fiber dispersion slurry is formed by pre-mixing water, polycarboxylate dispersant, and polyvinyl alcohol short fibers to ensure uniform distribution of short fibers in interlayer compensation material 3.

[0038] The sluggish expansion component, lightly calcined magnesia, is an active magnesia powder formed by calcining magnesite or dolomite at 850℃~1000℃ and then grinding it. The MgO content is not less than 80%, the activity index is 60s~180s, and the fineness is 100 mesh~325 mesh. Lightly calcined magnesia is used to continue to produce a slow-release expansion effect after the early hardening of the main concrete 2, enabling the interlayer compensation material 3 to form a sluggish compensation effect between adjacent main concrete layers 2, reducing the risk of microcracks forming at the interlayer interface due to later shrinkage differences.

[0039] The calcium sulfoaluminate expanded component is a sulfoaluminate clinker powder containing anhydrous calcium sulfoaluminate mineral phase, with the anhydrous calcium sulfoaluminate mineral phase content ranging from 35% to 65% and a specific surface area of ​​300 m². 2 / kg~500m 2 / kg, with a fineness of 100 mesh to 325 mesh. Calcium sulfoaluminate-based expanding components are used to generate ettringite-based expanding products in the early hydration stage, compensating for the early plastic shrinkage and drying shrinkage of interlayer compensator 3.

[0040] The anhydrite is natural anhydrite or calcined anhydrite, with a CaSO4 content of not less than 85%, a moisture content of not more than 1.0%, and a fineness of 100 mesh to 325 mesh. Anhydrite is used to provide a sulfate source for the calcium sulfoaluminate-based expansion components and to regulate the formation rate of ettringite, so that the expansion reaction of the interlayer compensator 3 matches the setting and hardening process of the main concrete 2.

[0041] When lightly calcined magnesium oxide, calcium sulfoaluminate, and anhydrite are combined as retarded expansion components, they form a certain amount of compensating expansion in the early stage and continue to compensate for shrinkage in the later stages, thereby forming a compensation interface with continuous stress regulation between the upper and lower main concrete layers 3.

[0042] The polycarboxylate-based powder water-reducing agent is a spray-dried polycarboxylate water-reducing agent powder with a water reduction rate of not less than 20%, a moisture content of not more than 5.0%, and a residue of not more than 10% on a 0.315mm sieve. The liquid polycarboxylate-based high-performance water-reducing agent has a solid content of 35% to 50%, a water reduction rate of not less than 25%, a pH value of 6 to 8, and a chloride ion content of not more than 0.1%. The water-reducing agent is used to reduce the water consumption of interlayer compensating material 3, improve the fluidity and interfacial spreadability of interlayer compensating material 3, and enable interlayer compensating material 3 to form a continuous and uniform compensation layer on the surface of the main concrete 2.

[0043] The pre-wetted lightweight porous ceramsite powder for internal curing is porous particle formed by crushing and screening shale ceramsite, clay ceramsite, or fly ash ceramsite. The particle size is 0.2mm–2.0mm, the cylinder compressive strength is not less than 2.0MPa, and the 24-hour water absorption rate is 10%–30%. Before use, the pre-wetted lightweight porous ceramsite powder is soaked in water for 12–24 hours until it reaches a saturated surface-dry state. The pre-wetted lightweight porous ceramsite powder is used to slowly release internal moisture during the hardening process of the interlayer compensating material 3, reducing the self-shrinkage of the interlayer compensating material 3 and improving the moisture retention capacity of the interlayer interface.

[0044] The acrylate-acrylamide copolymer water-absorbing resin granules have a dry particle size of 0.1 mm to 1.0 mm and a water absorption ratio of 8 to 30 times their own weight. They exhibit slow-release water capacity in cement-based alkaline environments. Before use, the water-absorbing resin granules are pre-absorbed to 60% to 90% of their saturated state, then pre-mixed with mineral admixtures and added to interlayer compensation material 3 to reduce particle agglomeration and improve dispersion uniformity.

[0045] When pre-wetted lightweight porous ceramsite powder and water-absorbing resin particles are used as internal curing particles, they form dispersed water storage points inside the interlayer compensating material 3 and release water during the hydration and hardening process of the interlayer compensating material 3. This reduces the early water loss shrinkage and autogenous shrinkage of the interlayer compensating material 3 and improves the interfacial bonding stability between the interlayer compensating material 3 and the upper and lower main concrete layers 2.

[0046] The polycarboxylate dispersant in the fiber dispersion pulp is a liquid polycarboxylate dispersant with a solid content of 20%–40% and a pH value of 6–8. It is used to reduce the agglomeration of polyvinyl alcohol (PVA) short fibers in the pulp. The PVA short fibers have a length of 3 mm–9 mm, a diameter of 10 μm–25 μm, a tensile strength of not less than 800 MPa, and an elastic modulus of not less than 20 GPa. To prepare the fiber dispersion pulp, the polycarboxylate dispersant is first added to water and stirred until homogeneous. Then, PVA short fibers are gradually added and stirred for 3–8 minutes to ensure a uniform suspension of the PVA short fibers in the aqueous phase.

[0047] After the fiber dispersion slurry is added to the interlayer compensator 3, the polyvinyl alcohol short fibers are evenly distributed in the interlayer compensator 3, reducing the agglomeration, clumping or local fiber loss caused by dry fiber feeding, and forming a microcrack bridging structure after the interlayer compensator 3 hardens, thereby improving the tensile toughness and interfacial crack resistance of the interlayer compensator 3.

[0048] The delayed expansion component enables the interlayer compensator 3 to have shrinkage compensation capacity in both early and later curing stages; the water-reducing agent improves the spreadability and compactness of the interlayer compensator 3; the internal curing particles reduce the auto-shrinkage and water loss shrinkage of the interlayer compensator 3; and the fiber dispersion paste enhances the crack resistance and toughness of the interlayer compensator 3. Thus, the interlayer compensator 3 can form an interlayer stress regulation interface that combines expansion compensation, internal moisture retention and curing, and fiber bridging between adjacent main concrete layers and within the constrained transition zone 12.

[0049] During pouring, the main concrete 2 is poured using a layered continuous pouring method. The thickness of each layer of main concrete 2 is 300mm to 400mm. After the lower layer of main concrete 2 is vibrated and compacted, its surface penetration resistance is measured using a penetration resistance meter. When the surface penetration resistance of the lower layer of main concrete 2 reaches 0.2MPa to 0.8MPa, interlayer compensation material 3 is laid on its upper surface. The thickness of the interlayer compensation material 3 in the main pouring area 11 is 8mm to 15mm, and the thickness of the interlayer compensation material 3 in the constrained transition area 12 is 15mm to 25mm. After the interlayer compensation material 3 is laid, a small-diameter vibrator 4 is used for secondary vibration, allowing the interlayer compensation material 3 to penetrate 10mm to 40mm into the surface of the lower layer of main concrete 2. Then, the next layer of main concrete 2 is poured on top, allowing the interlayer compensation material 3 to be vibrated and bonded to the upper and lower layers of main concrete 2.

[0050] During concrete pouring, temperature and humidity sampling points were set up in the core of the poured concrete, at a distance of 30mm to 80mm from the surface, and in the constrained transition zone 12. Temperature sampling points used embedded thermocouples or platinum resistance temperature sensors, while humidity sampling points used embedded concrete humidity sensors. After pouring, curing measures were adjusted based on the temperature difference between the core and surface, surface humidity, and the rate of temperature decrease in the core. When the temperature difference between the core and surface exceeded 18℃, an insulation covering layer was added; when the relative humidity of the surface was below 80%, misting was applied; when the rate of temperature decrease in the core exceeded 1.5℃ / h, the insulation covering time was extended to reduce the impact of early temperature shrinkage and drying shrinkage on the concrete structure 1.

[0051] After the initial curing of the concrete, the surface moisture content and capillary water absorption of the surface protection zone 13 were tested. The surface moisture content was 8%–16%, and the capillary water absorption over 10 minutes was 0.05 kg / m³. 2 ~0.30kg / m 2 At that time, it was determined that the concrete surface had reached the preset capillary water absorption state. Subsequently, the surface protection zone 13 was moistened and cleaned to remove laitance, loose particles and oil stains, and the surface was kept moist but without standing water.

[0052] The penetrating crystalline protective slurry layer 5 comprises, by weight: 100 parts silicate cement, 55 parts quartz sand, 12 parts silicate active component, 5 parts calcium salt activating component, 0.6 parts penetrating aid, 0.8 parts water-retaining and thickening component, and 45 parts water.

[0053] The silicate active component is a mixture of powdered sodium silicate, powdered potassium silicate, and metakaolin in a mass ratio of 4:2:3; the calcium salt activating component is a mixture of calcium formate, calcium nitrate, and calcium hydroxide in a mass ratio of 3:2:2; the penetrating aid is a mixture of low molecular weight polycarboxylate dispersant and silane coupling agent in a mass ratio of 5:1; and the water-retaining and thickening component is a mixture of hydroxypropyl methylcellulose ether, starch ether, and bentonite in a mass ratio of 4:1:5. The quartz sand is 80-120 mesh graded quartz sand.

[0054] Among them, the active silicate component, sodium silicate powder, is water-soluble sodium silicate powder with a modulus of 2.0 to 3.4, an active silica content of not less than 45%, and a particle size of 80 to 200 mesh. It is used to release migratable silicate ions in the water-containing environment of the concrete surface. The active potassium silicate powder is water-soluble potassium silicate powder with a modulus of 2.2 to 3.6, an active silica content of not less than 40%, and a particle size of 80 to 200 mesh. It is used to improve the dispersibility and migration of the active silicate component in the penetrating crystalline protective slurry layer 5 in the weakly alkaline pore liquid. The metakaolin is calcined kaolin powder with a loss on ignition of not more than 3.0%, an Al2O3 content of 35% to 45%, a SiO2 content of 45% to 55%, and an average particle size of 1 μm to 10 μm. It is used to participate in the secondary reaction of hydration products and improve the compactness of the protective slurry layer.

[0055] The calcium formate component of the calcium salt activation component is industrial-grade or building-grade calcium formate powder with a purity of not less than 90%, a moisture content of not more than 1.0%, and a particle size of 80-200 mesh. It is used to promote the early hardening of the penetrating crystalline protective slurry layer 5 and provide a soluble calcium source. The calcium nitrate component is industrial-grade calcium nitrate powder or granules with a purity of not less than 90% and a water-insoluble content of not more than 1.0%. It is used to provide soluble calcium ions in a humid environment and promote the reaction between the silicate active component and the pore fluid of the concrete surface. The calcium hydroxide component is slaked lime powder with a Ca(OH)2 content of not less than 85% and a fineness of 100-325 mesh. It is used to maintain the alkaline environment required for the penetrating crystallization reaction and to supplement the calcium source.

[0056] The low molecular weight polycarboxylate dispersant of the penetrating agent is a powder or liquid polycarboxylate dispersant with a number average molecular weight of 2000-12000 and a solid content of not less than 40%. It is used to improve the dispersion uniformity of silicate active components, calcium salt activating components and cement particles in the protective slurry and reduce local agglomeration. The silane coupling agent is one or more of aminopropyltriethoxysilane, glycidoxypropyltrimethoxysilane or methyltriethoxysilane. After hydrolysis, it forms silicon-oxygen bonds with the surface of cement-based materials and is used to improve the interfacial bonding and water erosion resistance of the protective slurry layer and the concrete surface layer.

[0057] The water-retaining and thickening component, hydroxypropyl methylcellulose ether, has a viscosity of 40,000 mPa·s to 100,000 mPa·s and an ash content of no more than 5.0%. It is used to improve the water retention and application properties of the protective slurry and reduce early water loss in the protective slurry layer. The starch ether is hydroxypropyl starch ether or modified potato starch ether, with a viscosity of 300 mPa·s to 1500 mPa·s. It is used to improve the anti-sagging and coating stability of the protective slurry. The bentonite is sodium-based bentonite or modified sodium-based bentonite, with a montmorillonite content of no less than 60% and an expansion ratio of no less than 15 mL / g. It is used to improve the thixotropy, water retention, and pore-filling capacity of the protective slurry layer.

[0058] The silicate active component migrates into the surface pores when the concrete surface is in a capillary water absorption state; the calcium salt activating component provides a calcium source that can participate in the reaction and maintains the reaction environment; the penetrating aid improves the dispersibility and interfacial bonding of the slurry; and the water-retaining and thickening component delays the early water loss of the protective slurry layer, so that the penetration crystallization reaction can continue under humid conditions, thereby improving the density and durability of the concrete surface bonded protective layer 6.

[0059] After thoroughly mixing the above-mentioned penetrating crystalline protective slurry layer 5, apply it to the concrete surface using a scraping or spraying method, controlling the wet film thickness to be 0.8mm–2.5mm. After construction, cover the concrete surface with the penetrating crystalline protective slurry layer 5 with a moist geotextile and perform moisture-curing for 3–7 days. This allows the active components in the penetrating crystalline protective slurry layer 5 to continuously migrate and react in the capillaries and micro-cracks of the concrete surface, forming a bonded protective layer 6.

[0060] In this embodiment, the main concrete 2, interlayer compensation material 3, temperature and humidity co-curing and penetrating crystalline protective slurry 5 correspond to material modification, interlayer stress regulation, early shrinkage control and surface durability protection, respectively. Through this construction process, temperature shrinkage cracks and drying shrinkage cracks can be reduced in the early hardening stage of concrete structure 1, and the erosive effects of moisture, chloride ions and freeze-thaw cycles on concrete structure 1 can be reduced during long-term service.

[0061] Example 2 This embodiment takes a basement floor slab as an example. The floor slab is designed to be 900mm thick, with a concrete strength grade of C40 and a permeability grade of not less than P8. The lower part of the floor slab is adjacent to the cushion layer and foundation cap, and is constrained by external walls, sump pits, elevator shafts, and post-cast strips, etc., making it a concrete structure with a high risk of early temperature shrinkage cracks and drying shrinkage cracks.

[0062] Before construction, based on the thickness of the base slab, the distribution of reinforcing bars, the boundaries of the formwork, and the location of the joints, the area to be poured is divided into three zones: the main pouring zone 11, the restrained transition zone 12, and the surface protection zone 13. Specifically, the restrained transition zone 12 is defined as the area within 300mm from the base of the outer wall, the corner of the sump, the boundary of the post-pouring strip, the edge of the foundation, and the sidewall of the formwork; the surface protection zone 13 is defined as the area within 0mm to 20mm from the top surface of the base slab; and the remaining area is defined as the main pouring zone 11.

[0063] The main concrete 2 uses the following mix proportions per cubic meter: 310 kg ordinary Portland cement, 70 kg fly ash, 80 kg mineral powder, 760 kg medium sand, 1050 kg crushed stone, 150 kg water, 6.5 kg polycarboxylate superplasticizer, 28 kg composite expansion component, and 1.4 kg crack-resistant fiber. The composite expansion component is formed by mixing calcium oxide-based expanded clinker, lightly calcined magnesia, and calcium sulfoaluminate-based expanded components in a mass ratio of 1:0.45:0.60. The crack-resistant fiber is formed by mixing polyvinyl alcohol fiber and polypropylene fiber in a mass ratio of 2:1, wherein the polyvinyl alcohol fiber length is 6 mm to 12 mm, and the polypropylene fiber length is 9 mm to 18 mm.

[0064] Interlayer compensation material 3, by weight, comprises the following components: 100 parts cement, 35 parts mineral powder, 12 parts delayed expansion component, 8 parts pre-wetted lightweight ceramsite powder, 5 parts fiber dispersion paste, 1.5 parts polycarboxylate superplasticizer, and 45 parts water. The delayed expansion component is formed by mixing lightly calcined magnesium oxide and calcium sulfoaluminate-based expansion components at a mass ratio of 1:0.4. The pre-wetted lightweight ceramsite powder is soaked in water for 24 hours before use, and added to interlayer compensation material 3 after the surface is dried to a saturated dry state. The fiber dispersion paste is formed by pre-dispersing water, dispersant, and polyvinyl alcohol short fibers to reduce fiber agglomeration.

[0065] During pouring, the base slab is poured continuously in three layers along its thickness, each layer being 300mm thick. After the first layer of main concrete 2 is poured and vibrated, its surface penetration resistance is tested. When the surface penetration resistance reaches 0.35MPa, interlayer compensation material 3 is evenly spread on the surface of the first layer of main concrete 2, with a thickness of 12mm. In the constrained transition zone 12 at the base of the outer wall, the corner of the sump pit, and the boundary of the post-pouring strip, the thickness of the interlayer compensation material 3 is increased to 18mm. Subsequently, a second vibration is performed to allow the interlayer compensation material 3 to penetrate to a depth of approximately 20mm into the surface of the first layer of main concrete 2, and the second layer of main concrete 2 is poured on top of it.

[0066] After the second layer of main concrete 2 is completed, the surface penetration resistance is tested in the same way, and interlayer compensation material 3 is laid when the surface penetration resistance reaches 0.42MPa. After the third layer of main concrete 2 is poured, the surface protection area 13 is treated by secondary troweling to make the surface mortar layer dense and without obvious bleeding.

[0067] During concrete pouring, temperature and humidity sensors were installed at the core of the base slab, 50mm from the top surface, in the constraint transition zone 12 at the base of the outer wall, and at the corner of the sump. After pouring, when the temperature difference between the core and the surface layer was greater than 18℃, the base slab surface was covered with plastic film, geotextile, and insulation felt; when the relative humidity of the surface layer was less than 80%, fine mist spraying was used to replenish moisture to avoid directly washing away the cement slurry; when the core temperature dropped at a rate greater than 1.5℃ / h, the insulation covering time was extended and the frequency of uncovering was reduced.

[0068] Five days after concrete pouring, the moisture content and capillary water absorption of the base slab surface were tested. The surface moisture content was 12%, and the capillary water absorption over 10 minutes was 0.14 kg / m³. 2 When the time is right, determine when the penetrating crystalline protective slurry layer is ready for construction. Before construction, clean the surface laitance and loose particles, and wet the surface with atomized water to make the surface moist but without standing water.

[0069] The penetrating crystalline protective slurry layer 5, by weight, comprises the following components: 100 parts silicate cement, 55 parts 80-120 mesh quartz sand, 12 parts silicate active component, 5 parts calcium salt activating component, 0.6 parts penetrating aid, 0.8 parts hydroxypropyl methylcellulose, and 45 parts water. After mixing the above materials into a uniform slurry, apply it to the surface of the substrate using a scraping method, achieving a wet film thickness of 1.5 mm. After construction, cover with a moist geotextile and cure for 3 days, keeping the geotextile moist during this period. The protective slurry layer must not be exposed to direct sunlight or experience rapid water loss.

[0070] Through the above construction method, the interlayer compensation material 3 forms a compensation interface with delayed expansion and internal curing effect between adjacent pouring layers, constrains the transition zone 12 to obtain stronger local shrinkage compensation, and the penetrating crystalline protective slurry layer 5 enters the pores of the concrete surface under suitable capillary water absorption and forms a crystalline closed structure.

[0071] Example 3 This embodiment takes the basement exterior wall as an example. The wall thickness is 350mm, the height is 4.2m, the concrete strength grade is C35, and the impermeability grade is not lower than P8. The basement exterior wall is significantly constrained by the floor slab, and the base of the wall, internal and external corners, construction joints, and the area around the through-wall sleeves are high-risk areas for cracks and leakage.

[0072] Before construction, the area within 500mm from the wall base, the area within 300mm on both sides of the internal and external corners, the area within 300mm on both sides of the construction joint, and the area within 200mm around the wall sleeve are designated as the constraint transition zone 12; the area within 0mm to 20mm from the surface of the water-facing side of the exterior wall is designated as the surface protection zone 13; the remaining wall area is designated as the main pouring zone 11.

[0073] The main concrete 2 uses the following mix proportions per cubic meter: 300 kg cement, 65 kg fly ash, 75 kg mineral powder, 780 kg medium sand, 1030 kg crushed stone, 155 kg water, 6.0 kg polycarboxylate superplasticizer, 25 kg composite expansion component, and 1.2 kg crack-resistant fiber. The composite expansion component is formed by mixing calcium oxide-based expanded clinker, lightly calcined magnesia, and calcium sulfoaluminate-based expanded components in a mass ratio of 1:0.35:0.55. The crack-resistant fiber is formed by mixing polypropylene fiber and basalt fiber in a mass ratio of 1:1.

[0074] Interlayer compensation material 3, by weight, comprises the following components: 100 parts cement, 25 parts fly ash, 10 parts delayed expansion component, 4 parts water-absorbing resin granules, 4 parts fiber dispersion paste, 1.2 parts water-reducing agent, and 42 parts water. Before use, the water-absorbing resin granules are pre-absorbed with water to 8 to 15 times their own weight and pre-mixed with fly ash before being added to the mixer to improve their dispersion uniformity in the paste.

[0075] The exterior wall is poured in layers continuously along its height, with each layer being 400mm high. After each layer of main concrete 2 is poured and vibrated, when the surface penetration resistance reaches 0.25MPa to 0.60MPa, interlayer compensation material 3 with a thickness of 8mm to 15mm is laid along the wall base, internal and external corners, construction joints, and the constraint transition zone 12 around the wall sleeves; interlayer compensation material 3 with a thickness of 5mm to 10mm is laid at the interlayer locations of ordinary wall sections. After laying, a small-diameter vibrator 4 is used for short-term secondary vibration to ensure that the interlayer compensation material 3 forms an interlocking transition with the upper and lower layers of main concrete 2.

[0076] Before and after the removal of the exterior wall formwork, temperature and humidity were monitored at the core of the wall, 50mm from the water-facing surface, and the constraint transition zone 12 at the wall base. When the temperature difference between the core of the wall and the surface of the water-facing surface was greater than 15℃, the formwork removal was delayed or the wall was immediately covered with a heat-insulating and moisture-retaining cloth after removal. When the relative humidity of the surface of the water-facing surface was lower than 82%, atomized water was used for humidification. When the temperature drop rate of the core was greater than 1.2℃ / h, the insulation cover was maintained for no less than 24 hours before the next inspection.

[0077] Between the 4th and 7th day after demolding, the capillary water absorption status of the water-facing surface was tested. The test was conducted when the surface moisture content was 10%–15% and the capillary water absorption rate was 0.08 kg / m³ over 10 minutes. 2 ~0.22kg / m 2During construction, apply the penetrating crystalline protective slurry layer 5. For the perimeter of the wall sleeve, both sides of the construction joint, and internal and external corners, first use a brush to repeatedly apply the penetrating crystalline protective slurry layer 5 along the joint edge or corner, then spray the entire layer. The wet film thickness should be controlled to 1.2mm–2.0mm. After construction, cover with a moisturizing membrane and geotextile for curing for 3–5 days.

[0078] In this embodiment, the interlayer compensation material 3 forms multiple spaced compensation interfaces along the height of the exterior wall, while simultaneously forming localized reinforced compensation zones at the wall base, construction joints, internal and external corners, and around the wall sleeves. This construction method is used to reduce the risk of vertical cracks in the exterior wall caused by the constraint of the base slab, temperature drop shrinkage, and surface water loss, and to improve the water-facing side's resistance to seepage and chloride ion intrusion.

[0079] Example 4 To verify the crack resistance and durability improvement effects of the construction method of this invention, basement floor slab test sections with the same strength grade, thickness, and construction environment were selected for comparison. The control group adopted the conventional crack-resistant concrete construction method, that is, the main concrete 2 was mixed with an expansion agent and polypropylene fiber, and layered pouring, covering with a film and water curing were carried out. After demolding, cement-based penetrating crystalline material was directly applied. The test group adopted the construction method of Example 1 of this invention, that is, composite expansion component and composite crack-resistant fiber were used in the main concrete 2, interlayer compensation material 3 was placed between adjacent pouring layers and in the constrained transition zone 12, and the curing and construction timing of the penetrating crystalline protective slurry layer 5 were controlled according to the temperature, humidity and surface capillary water absorption state.

[0080] Both test sections have an area of ​​100m². 2 The base slab area has a designed concrete thickness of 800mm and a concrete strength grade of C40. Surface cracks were inspected at 3d, 7d, 14d, and 28d after pouring, and core samples were taken at 28d to test compressive strength, chloride ion flux, impermeability grade, and freeze-thaw mass loss rate.

[0081] The test results are as follows: Number of visible cracks on 3D surface <![CDATA[7 pieces / 100m 2 > <![CDATA[2 pieces / 100m 2 > Number of visible cracks on the surface in 7d <![CDATA[11 pieces / 100m 2 > <![CDATA[3 strips / 100 m 2 > Number of visible cracks on the surface in 14d <![CDATA[13 pieces / 100m 2 > <![CDATA[3 pieces / 100m 2 > Number of visible cracks on the surface 28d <![CDATA[15 strips / 100m 2 > <![CDATA[4 pieces / 100m 2 > 28-day maximum crack width 0.18mm 0.06mm 28-day compressive strength 46.5MPa 48.2MPa 28-day chloride ion flux 1280C 690C impermeability grade P8 P12 mass loss rate after 100 freeze-thaw cycles 2.8% 1.4% The results above show that, under the same construction environment and similar main mix proportions, the number of cracks in the control group increased rapidly from 3 to 14 days, indicating that conventional crack-resistant concrete construction methods are still insufficient to fully suppress early temperature shrinkage and drying shrinkage cracks. The number of visible surface cracks in the experimental group at 3, 7, 14, and 28 days was lower than that in the control group, and the maximum crack width at 28 days was significantly smaller. This indicates that the present invention, through interlayer compensation material 3, local compensation in the constrained transition zone 12, and temperature and humidity synergistic curing, can effectively reduce the risk of crack formation in the early stages of concrete hardening.

[0082] Meanwhile, the chloride ion flux of the experimental group was lower than that of the control group after 28 days, the impermeability grade increased from P8 to P12, and the mass loss rate decreased after 100 freeze-thaw cycles. This indicates that the construction of the penetrating crystalline protective slurry layer 5 after the concrete surface reaches the preset capillary water absorption state is conducive to the migration of active components into the capillary pores and micro-cracks of the concrete surface and the formation of a closed structure, thereby improving the impermeability, chloride ion intrusion resistance and freeze-thaw durability of the concrete structure 1.

[0083] The above test results show that the present invention does not simply rely on increasing the amount of expansion agent, fiber or waterproof material to improve performance, but rather achieves improved crack resistance and long-term durability of concrete structure 1 by combining the modification of the main concrete 2 material, stress regulation of interlayer compensation material 3, temperature and humidity synergistic curing and capillary activated surface protection, thus forming a continuous construction closed loop.

[0084] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described.

Claims

1. A construction method for a high crack-resistant and long-durability concrete structure, characterized in that, The steps include: S1. Based on the thickness of the concrete structure to be constructed, the location of the boundary constraints, and the location of the exposed surface, the area to be constructed is divided into the main pouring area, the constraint transition area, and the surface protection area. S2. Prepare the main concrete and interlayer compensation material, wherein the main concrete contains a composite expansion component and crack-resistant fibers, and the interlayer compensation material contains a delayed expansion component, internal curing particles and fiber dispersion paste; S3. The main concrete is poured in a layered continuous pouring manner. Interlayer compensation material is placed between two adjacent layers of main concrete and in the constrained transition zone. The interlayer compensation material is vibrated and compacted with the adjacent upper and lower layers of main concrete. S4. Collect temperature and humidity data in the core of the poured concrete, at a distance of 30mm to 80mm from the surface, and in the constrained transition zone. Adjust the covering, moisturizing, spraying, and heat preservation measures according to the temperature difference between the core and the surface and the surface humidity. S5. After the concrete surface reaches the preset capillary water absorption state, the surface protection area is moistened and cleaned, and a penetrating crystalline protective slurry layer is applied. S6. Moisturize and cure the concrete surface with the penetrating crystalline protective slurry layer during construction until the penetrating crystalline protective slurry layer and the concrete surface layer are bonded together to form a bonded protective layer. The interlayer compensation material comprises, by weight, 100 parts cement, 20-60 parts mineral admixture, 8-18 parts delayed expansion component, 3-12 parts internal curing particles, 2-8 parts fiber dispersion paste, 0.8-2.5 parts water-reducing agent, and 35-55 parts water; the internal curing particles are pre-wetted lightweight porous particles or water-absorbing resin particles. The mineral admixtures in the interlayer compensation material include at least two of granulated blast furnace slag powder, fly ash, and silica fume; the retardant expansion component includes lightly calcined magnesium oxide, calcium sulfoaluminate expansion component, and gypsum sulfate component; the water-reducing agent is a polycarboxylate-based water-reducing agent; and the internal curing particles include at least one of pre-wetted lightweight porous ceramsite powder and water-absorbing resin particles.

2. The construction method according to claim 1, characterized in that, In S1, the main pouring area is the concrete pouring area other than the constraint transition area and the surface protection area; the constraint transition area includes the location near the existing concrete joint surface, construction joint, corner, dense reinforcement area, formwork sidewall or foundation constraint boundary; the surface protection area is the area 0mm to 20mm away from the exposed concrete surface.

3. The construction method according to claim 1, characterized in that, The main concrete, per cubic meter, includes: 250kg-360kg cement, 80kg-180kg mineral admixtures, 650kg-850kg fine aggregate, 950kg-1150kg coarse aggregate, 130kg-170kg water, 4kg-9kg water-reducing agent, 18kg-38kg composite expansion component, and 0.6kg-2.2kg crack-resistant fiber; The mineral admixture includes at least two of the following: fly ash, granulated blast furnace slag powder, and silica fume; the fine aggregate is medium sand; the coarse aggregate is continuously graded crushed stone; and the water-reducing agent is a polycarboxylate-based high-performance water-reducing agent.

4. The construction method according to claim 3, characterized in that, The composite expansion component includes calcium oxide expanded clinker, lightly calcined magnesium oxide, and calcium sulfoaluminate expanded component, with a mass ratio of 1:(0.25-0.65):(0.35-0.85). The crack-resistant fiber includes at least two of polyvinyl alcohol fiber, polypropylene fiber, and basalt fiber.

5. The construction method according to claim 1, characterized in that, In S3, the pouring thickness of each layer of the main concrete is 250mm to 500mm; after the lower layer of main concrete has been vibrated and compacted, when its surface penetration resistance reaches 0.2MPa to 0.8MPa, the interlayer compensation material is laid. The interlayer compensation material is laid with a thickness of 5mm to 25mm, and the interlayer compensation material is inserted into the interface of the adjacent main concrete to a depth of 10mm to 40mm through secondary vibration.

6. The construction method according to claim 1, characterized in that, In S4, when the temperature difference between the core and surface of the poured concrete is greater than 18°C, an insulation covering layer is added. Spraying should be done when the relative humidity of the surface of the poured concrete is below 80%. Extend the insulation covering time when the core temperature of the poured concrete drops at a rate greater than 1.5℃ / h.

7. The construction method according to claim 1, characterized in that, In S5, the preset capillary water absorption state is: the surface moisture content of the concrete is 8% to 16%, and the capillary water absorption of the surface is 0.05 kg / m2 to 0.30 kg / m2 in 10 minutes; after the preset capillary water absorption state is reached, the penetrating crystalline protective slurry layer is scraped or sprayed onto the concrete surface.

8. The construction method according to claim 7, characterized in that, The permeable crystalline protective slurry layer comprises, by weight: 100 parts silicate cement, 35 to 80 parts quartz sand, 5 to 18 parts silicate active component, 2 to 8 parts calcium salt activating component, 0.1 to 1.2 parts permeability aid, 0.2 to 1.5 parts water-retaining and thickening component, and 35 to 60 parts water; The silicate active component includes at least one of powdered sodium silicate, powdered potassium silicate, and metakaolin; the calcium salt activating component includes at least one of calcium formate, calcium nitrate, and calcium hydroxide; the penetration aid includes at least one of polycarboxylate dispersant and silane coupling agent; and the water-retaining and thickening component includes at least one of cellulose ether, starch ether, and bentonite.

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