Anti-loosening and binding-free concrete protection layer cushion block and preparation method thereof

Abstract

The present application relates to the field of concrete protective layer cushion block, and particularly relates to a kind of anti-loosening and binding-free concrete protective layer cushion block and its preparation method.A kind of anti-loosening and binding-free concrete protective layer cushion block, characterized by, including fixedly connected support layer and fixed layer, the fixed layer is equipped with at least one group of fixed slot for the clamping of reinforcing steel, the fixed layer includes layer thickness 3-8mm, porosity 25%-35%, average pore size 0.5-2mm porous concrete prefabricated framework, the support layer includes porosity 15%-25%, average pore size 0.3-1mm porous concrete prefabricated framework;The present application constructs the cushion block basic framework of double-layer gradient porous structure, substantially improves the bearing capacity of cushion block, guarantees the structural stability of cushion block under complex working conditions such as construction treading, high-frequency vibration and so on.

Description

Technical Field

[0001] This invention relates to the field of concrete protective layer spacers, specifically to an anti-loosening, non-binding concrete protective layer spacer and its preparation method. Background Technology

[0002] Reinforced concrete cover spacers are core functional components in cast-in-place and prefabricated concrete structure construction, crucial for precisely controlling the thickness of the concrete cover, ensuring structural load-bearing capacity, fire resistance, and long-term durability. Existing cover spacer technology faces long-standing industry pain points and technical bottlenecks that have been difficult to overcome.

[0003] Traditional cement-based blocks have inherent defects such as high brittleness and poor impact resistance. When reinforcing bars are pressed in and fixed, they are prone to problems such as slotting, cracking, and corner chipping. Furthermore, they only have planar contact with the main concrete, resulting in weak interfacial adhesion. After long-term service, they are prone to interfacial debonding and cracking, forming channels for harmful ion penetration. At the same time, they need to be fixed by binding wire, which results in low construction efficiency and high labor costs. They are also prone to loosening and displacement during vibration, and the thickness control accuracy of the protective layer is poor.

[0004] Although plastic blocks can achieve fixation without binding, their coefficient of thermal expansion differs significantly from that of the concrete matrix, inevitably leading to interface debonding during service. Furthermore, the material is prone to aging and has weak resistance to vibration and impact, making it impossible to achieve the same service life as the main structure. It also has environmental drawbacks.

[0005] Existing porous concrete blocks mostly employ a single homogeneous structure, failing to simultaneously meet the core requirements of high interconnected porosity and high load-bearing capacity. Either the porosity is insufficient to achieve interfacial interlocking with the main concrete, or the porosity is too high, resulting in insufficient load-bearing capacity to withstand construction loads and vibration impacts. Existing layered concrete blocks are often simple stacks of different materials with only physical bonding between layers. Under load and vibration, they are highly susceptible to delamination and interfacial debonding. They cannot achieve performance gradient matching through a porous-injection interlocking structure, nor can they fundamentally resolve the inherent contradiction between the brittleness of cement-based materials and their ability to be locked in place without binding. Summary of the Invention

[0006] In view of the technical problems existing in the prior art, the present invention provides a concrete protective layer pad block that is resistant to loosening and does not require binding, and a method for preparing the same.

[0007] In the first aspect, this application provides a concrete protective layer pad that prevents loosening and requires no binding, employing the following technical solution: A concrete protective layer pad for preventing loosening and eliminating the need for binding, characterized in that it comprises a fixedly connected support layer and a fixing layer, wherein the fixing layer is provided with at least one set of fixing grooves for clamping reinforcing bars, the fixing layer comprises a porous precast concrete skeleton with a thickness of 3-8mm, a porosity of 25%-35%, and an average pore diameter of 0.5-2mm, and the support layer comprises a porous precast concrete skeleton with a porosity of 15%-25% and an average pore diameter of 0.3-1mm.

[0008] Through the above technical solution, this application constructs a double-layer gradient porous structure for the foundation block, completely breaking the inherent technical bias of traditional homogeneous foundation blocks. Addressing the differentiated functional requirements of the fixing layer and the supporting layer, a porous precast concrete skeleton with different pore characteristics is designed. The fixing layer adopts a high-porosity porous structure, giving the fixing slots sufficient micro-deformation capability, fundamentally solving the problem of easy cracking when reinforcing steel is pressed into traditional cement-based foundation blocks, while also reserving a stable structural foundation for subsequent interlocking with the main concrete interface. The supporting layer adopts a lower-porosity porous structure, significantly improving the load-bearing capacity of the foundation block while maintaining material connectivity, ensuring the structural stability of the foundation block under complex working conditions such as construction foot traffic and high-frequency vibration.

[0009] Furthermore, it also includes an intermediate transition layer, at least a portion of which is disposed between the support layer and the fixing layer, so that the support layer, the intermediate transition layer and the fixing layer form a seamless, layered whole.

[0010] By employing the aforementioned technical solution, this application addresses the technical problem of delamination and breakage in existing layered pad blocks where interlayer bonding relies solely on physical bonding. It introduces an intermediate transition layer as the core link for the coordinated stress distribution of the three-layer structure. This intermediate transition layer fills the space between the support layer and the fixing layer. Through a penetration-curing molding process, it forms a three-dimensional, interpenetrating, deeply bonded structure with the porous skeletons of the upper and lower layers, completely eliminating the physical bonding interface between the layers. This fundamentally avoids the delamination, debonding, and breakage failure problems that are prone to occur in traditional composite structures under vibration, impact, and load. Simultaneously, the intermediate transition layer enables a smooth gradient transition of material properties between the upper and lower layers, effectively eliminating stress concentration between structures with different porosities. This significantly improves the overall structural stability and impact resistance of the pad block, allowing the support layer, intermediate transition layer, and fixing layer to form a complete, coordinated stress-bearing whole.

[0011] Furthermore, the fixing layer comprises the following substances in parts by weight: 30-50 parts of silicate cement; 10-15 parts mineral powder; 8-12 parts fly ash; 3-5 parts silica fume; 1.0-1.5 parts of expanding agent; 3-5 parts of porous ceramsite; 1-2 parts calcium carbonate; 0.5-0.8 parts stainless steel fiber; 0.2-0.3 parts of polycarboxylate superplasticizer; 0.1-0.2 parts of organosilicon water-repellent agent; Foaming agent 0.05-0.10 parts; 10-15 parts water.

[0012] Through the above technical solutions, this application uses silicate cement as the core cementitious base, ensuring the homogeneity of hydration between the spacer block and the main concrete, and completely avoiding interfacial compatibility defects caused by different cementitious systems. The optimized compounding of mineral admixtures effectively improves the hydration process of the cementitious system, significantly enhancing the toughness of the porous skeleton and the workability of the mix. The synergistic introduction of various functional powders and reinforcing fibers ensures the molding stability of the porous structure and endows the skeleton with excellent crack and impact resistance, effectively preventing the spalling problem during the pressing of the reinforcing bars. The combination of functional admixtures precisely controls the pore characteristics and durability of the fixing layer, ensuring the structural stability of the interconnected pores and improving the impermeability and erosion resistance of the spacer block, perfectly meeting the core functional requirements of the fixing layer.

[0013] Furthermore, the support layer comprises the following parts by weight: 42-50 parts of silicate cement; 6-8 parts silica fume; 2-3 parts of nano-calcium carbonate; 3-5 parts of wollastonite whiskers; 2-4 parts of calcium carbonate whiskers; 0.8-1.2 parts of 3mm steel fiber; 3-5 parts quartz powder; 0.5-1.0 parts of anhydrous gypsum; 0.2-0.4 parts of 3mm PVA nanofibers; 0.1-0.2 parts of hydroxylated multi-walled carbon nanotubes; 0.3-0.4 parts of polycarboxylate superplasticizer; Foaming agent 0.05-0.1 parts; 10-13 parts water.

[0014] Through the above technical solution, this application uses silicate cement as the cementitious matrix, combined with ultrafine active powder to enhance the density and hydration activity of the matrix, providing a stable basic strength for the porous skeleton. The synergistic combination of two types of needle-like whiskers and ultrashort reinforcing fibers forms a randomly overlapping three-dimensional shear network in the matrix, significantly improving the shear strength and fatigue resistance of the slot structure, effectively solving the industry pain points of traditional cement-based slots being prone to cracking under high-frequency vibration and easy wear of the locking structure. The introduction of nano-modified components optimizes the material's ultimate deformation capacity without reducing the rigidity of the matrix, while precisely controlling the forming accuracy of the porous structure, comprehensively ensuring the long-term stability of the locking function.

[0015] Furthermore, the intermediate transition layer is prepared by curing a high-flowability micro-expansion cementitious slurry, which comprises the following components by weight: 45-55 parts of silicate cement; 5-10 parts silica fume; 2-5 parts of nano-calcium carbonate; 1-3 parts of expanding agent; 0.5-1.0 parts of polycarboxylate superplasticizer; Defoamer 0.1-0.2 parts; Hydroxypropyl methylcellulose ether 0.05-0.1 parts; 20-25 parts water.

[0016] Through the aforementioned technical solution, this application uses silicate cement of the same origin as the upper and lower skeleton layers as the cementitious base, ensuring the synergy of the hydration process of the entire system of the pad block, and completely avoiding the problem of interlayer shrinkage cracking caused by hydration mismatch. The introduction of ultrafine active powder significantly optimizes the particle size distribution and flow properties of the slurry, ensuring the full penetration and uniform filling of the interconnected pores of the porous skeleton. The combination of composite expansion components achieves precise shrinkage compensation of the slurry throughout its entire life cycle, effectively avoiding the problems of shrinkage debonding and interfacial micro-cracks after the slurry has cured. The synergistic regulation of multiple functional admixtures not only ensures the excellent flowability and water retention of the slurry, avoiding bleeding and segregation, but also significantly improves the interfacial bonding strength between the cured slurry and the porous skeleton, providing a solid material foundation for the seamless bonding of the three-layer structure.

[0017] Furthermore, the initial fluidity of the high-fluidity micro-expansion cement-based slurry is ≥300mm, and the fluidity loss is ≤20mm after 1 hour.

[0018] Through the aforementioned technical solution, this application ensures that the grout, during low-pressure grouting, can fully fill the reserved gaps between upper and lower layers and simultaneously penetrate into the interconnected pores of the porous skeleton by precisely controlling the initial flow properties and the loss of performance over time. This ultimately forms a stable, interlocking, three-dimensional interpenetrating structure. The excellent and stable flow properties effectively avoid common problems during grouting, such as incomplete filling, insufficient pore penetration, and grout segregation and pore blockage, completely solving the industry pain points of interface delamination and poor interlayer bonding that are common with traditional grouting materials. Simultaneously, the stable performance over time ensures the consistency of grout performance during batch construction, significantly improving the yield and performance stability of the pad blocks during mass production, providing a reliable technical guarantee for the industrial-scale production of pad blocks.

[0019] Secondly, this application provides a method for preparing a concrete protective layer pad that prevents loosening and requires no binding, using the following technical solution: A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Prepare fixed layer mixture according to formula, fill it into outer layer molding mold, vibrate to form and prefabricate the non-binding locking groove in one piece, pre-curing until initial setting, to obtain outer layer porous prefabricated skeleton. S2. Precast support layer: Prepare porous concrete mix for the internal support layer according to the formula, fill it into the core mold, vibrate and press it into shape, and pre-cur it until initial setting to obtain the internal load-bearing porous precast skeleton. S3. Coaxial mold positioning: The outer porous precast skeleton and the inner load-bearing porous precast skeleton after initial setting are coaxially fixed in the pouring mold, with a 2-5mm annular pouring gap reserved between the two layers. S4. Low-pressure injection interlocking molding: Prepare high-fluidity micro-expansion cement-based slurry according to the formula, and use a low-pressure injection process of 0.2-0.3MPa to inject the slurry from the bottom injection port of the mold. Stop the injection after the slurry overflows evenly from the top overflow port, and seal the injection port and the overflow port. S5. Curing and molding: After the filling is completed, the pad block is left to stand in the mold and then demolded and cured to prepare a porous interlocking gradient functional concrete protective layer pad block.

[0020] Through the aforementioned technical solution, this application first prefabricates the porous skeleton of the fixing layer and the supporting layer separately, which can precisely control the pore structure and molding accuracy of the two layers. The integrated prefabricated locking groove ensures the dimensional consistency and molding quality of the tie-free structure. The coaxial mold positioning process precisely ensures the coaxiality of the upper and lower layers and the uniformity of the injection gap, effectively avoiding uneven stress and performance defects caused by structural eccentricity. The low-pressure injection process achieves uniform filling and full penetration of the intermediate layer slurry, avoiding the problems of porous skeleton deformation and pore blockage caused by high-pressure injection.

[0021] Furthermore, the maintenance treatment includes the following maintenance steps: S1 Micro-positive pressure infiltration water retention curing: After the grouting is completed, the mold with pad blocks is transferred to apply constant micro-positive pressure, which drives the intermediate layer slurry to infiltrate into the interconnected pores of the inner and outer layers until the slurry initially sets; S2 Hydration Synchronous Gradient Temperature Curing: After the initial setting of the slurry, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the final setting of the slurry. S3 Gradient Humidity Intensity Growth Curing: After the slurry has set, maintain constant temperature and humidity, and introduce saturated calcium hydroxide curing solution every 24 hours for pressure curing. S4 Interface Enhancement and Stabilization Curing: From day 14 to day 21 of curing, place the entire pad in a standard curing environment with 93-97% humidity and 18-22℃ for 28 days to obtain the finished pad.

[0022] Through the above technical solutions, this application constructs a complete phased, gradient-coordinated curing system, completely breaking through the technical limitations of traditional homogeneous curing. The infiltration and water-retaining curing stage after grouting ensures the full penetration and filling of porous pores by the intermediate layer grout, effectively avoiding early bleeding, pore blockage, and interface voids. The hydration-synchronous gradient temperature curing stage precisely matches the hydration processes of the precast skeleton and the grouting material, fundamentally eliminating interlayer shrinkage differences and interface micro-cracks caused by asynchronous hydration. The gradient humidity curing stage differentiates and satisfies the dual requirements of high-strength and dense support layer and pore-retaining and toughening fixation layer, solving the technical problem that traditional curing cannot simultaneously address the differentiated performance of the two layers.

[0023] In summary, this application has the following beneficial effects: First, this application utilizes a double-layer porous skeleton structure with gradient porosity to endow the fixing slot with reversible micro-deformation capability, enabling the reinforcing bars to be pressed in without cracking and pre-locking without binding. Combined with the three-dimensional interpenetrating rigid interlocking structure formed after the intermediate transition layer is poured and cured, it achieves full-cycle performance adaptation of "elastic yielding during installation to permanent rigid locking during service," completely solving the industry pain points of traditional pads cracking during pressing and loosening during vibration. At the same time, the fully connected porous structure of the fixing layer forms aggregate interlocking with the newly poured main concrete, and the homogeneous cementitious system achieves hydration synergy, significantly improving the interface bonding strength. This fundamentally eliminates durability defects such as interface debonding and harmful ion penetration channels, enabling it to serve the same lifespan as the main structure.

[0024] Secondly, the entire system of this application adopts a cementitious base that is of the same origin as the main concrete, ensuring the matching of hydration process, shrinkage deformation, and thermal expansion coefficient throughout the entire cycle, and avoiding interface compatibility defects of different material systems. For the differentiated functional requirements of the fixing layer, support layer, and intermediate transition layer, exclusive modified formulas are designed respectively. The formula of the fixing layer takes into account high toughness and pore preservation as well as crack resistance and impact resistance, the formula of the support layer ensures high load-bearing capacity and low shrinkage, and the slurry of the intermediate layer achieves high permeability, micro-expansion and no shrinkage. This breaks through the technical bottleneck that traditional homogeneous materials cannot simultaneously take into account high porosity, high load-bearing capacity, high toughness and high durability, and realizes precise matching and synergistic optimization of the performance of each functional area of ​​the pad block.

[0025] Third, the use of a split prefabrication process precisely controls the pore structure of the double-layer porous skeleton and the forming accuracy of the locking groove, solving the problem that integral casting cannot achieve precise control of gradient porosity; the low-pressure grouting process achieves 100% filling of the porous pores by the intermediate layer grout, forming an interface-free layered overall structure; the staged gradient synergistic curing process realizes the synchronization of the hydration process of the prefabricated skeleton and the grouting material, and differentiates the performance of the inner and outer layers, completely eliminating problems such as interlayer shrinkage cracks, pore blockage, and uneven performance from the process, greatly improving the yield, dimensional accuracy and performance stability of the pad blocks, adapting to industrial-scale production, and solving the industry pain point that traditional processes cannot stably prepare gradient functional pad blocks. Detailed Implementation

[0026] The present application will be further described in detail below with reference to the embodiments.

[0027] Cement: P・O42.5 Portland cement; Mineral powder: S95 mineral powder; Fly ash: Grade I; Expanding agent: SY-G expanding agent; Porous ceramsite: Stainless steel fiber: 3mm long chopped stainless steel fiber; Hydroxylated multi-walled carbon nanotubes: CAS No.: 308068-56-6; Preparation Example 1 Fixed layer mix 1 30kg silicate cement, 10kg mineral powder, 8kg fly ash, 3kg silica fume, 1.0kg expansion agent, 3-5kg porous ceramsite, 1kg calcium carbonate, 0.5kg stainless steel fiber, 0.2kg polycarboxylate superplasticizer, 0.1kg organosilicon water-repellent agent, 0.05kg foaming agent, and 10kg water.

[0028] Preparation Example 2 Fixed layer mix 2 40kg silicate cement, 12kg mineral powder, 10kg fly ash, 4kg silica fume, 1.2kg expansion agent, 4kg porous ceramsite, 1kg calcium carbonate, 0.6kg stainless steel fiber, 0.2kg polycarboxylate superplasticizer, 0.1kg organosilicon water-repellent agent, 0.08kg foaming agent and 12kg water.

[0029] Preparation Example 3 Fixed layer mix 3 50kg silicate cement, 15kg mineral powder, 12kg fly ash, 5kg silica fume, 1.5kg expanding agent, 5kg porous ceramsite, 2kg calcium carbonate, 0.8kg stainless steel fiber, 0.3kg polycarboxylate superplasticizer, 0.2kg organosilicon water-repellent agent, 0.10kg foaming agent, and 15kg water.

[0030] Preparation Example 4 Support layer porous concrete mix 1 42kg silicate cement, 6kg silica fume, 2kg nano calcium carbonate, 3kg wollastonite whiskers, 2kg calcium carbonate whiskers, 0.8kg 3mm long steel fiber, 3kg quartz powder, 0.5kg anhydrous gypsum, 0.2kg 3mm long PVA nanofibers, 0.1kg hydroxylated multi-walled carbon nanotubes, 0.3kg polycarboxylate superplasticizer, 0.05kg foaming agent, and 10kg water.

[0031] Preparation Example 5 Support layer porous concrete mix 2 48kg silicate cement, 7kg silica fume, 2kg nano calcium carbonate, 4kg wollastonite whiskers, 3kg calcium carbonate whiskers, 1.0kg 3mm long steel fiber, 4kg quartz powder, 0.8kg anhydrous gypsum, 0.3kg 3mm long PVA nanofibers, 0.1kg hydroxylated multi-walled carbon nanotubes, 0.4kg polycarboxylate superplasticizer, 0.08kg foaming agent, and 11kg water.

[0032] Preparation Example 6 Support layer porous concrete mix 3 50kg silicate cement, 8kg silica fume, 3kg nano calcium carbonate, 5kg wollastonite whiskers, 4kg calcium carbonate whiskers, 1.2kg 3mm long steel fiber, 5kg quartz powder, 1.0kg anhydrous gypsum, 0.4kg 3mm long PVA nanofibers, 0.2kg hydroxylated multi-walled carbon nanotubes, 0.4kg polycarboxylate superplasticizer, 0.1kg foaming agent, and 13kg water.

[0033] Preparation Example 7 High-flowability micro-expansion cement-based slurry 1 45kg silicate cement, 5kg silica fume, 2kg nano calcium carbonate, 1kg expansion agent, 0.5kg polycarboxylate superplasticizer, 0.1kg defoamer, 0.05kg hydroxypropyl methylcellulose ether, 20kg water.

[0034] Preparation Example 8 High-flowability micro-expansion cement-based slurry 2 50kg silicate cement, 8kg silica fume, 3kg nano calcium carbonate, 2kg expansion agent, 0.8kg polycarboxylate superplasticizer, 0.1kg defoamer, 0.08kg hydroxypropyl methylcellulose ether, 22kg water.

[0035] Preparation Example 9 High-flowability micro-expansion cement-based slurry 3 55kg silicate cement, 10kg silica fume, 5kg nano calcium carbonate, 3kg expansion agent, 1.0kg polycarboxylate superplasticizer, 0.2kg defoamer, 0.1kg hydroxypropyl methylcellulose ether, 25kg water. Example

[0036] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 1. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 3 mm, a porosity of 25%, and an average pore diameter of 0.5 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 1 for the internal support layer. Fill the core mold, vibrate at a frequency of 50 Hz for 15 s to remove air, and then use a static pressure of 4 MPa to form the mold. Hold the pressure for 25 s and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 15% and an average pore diameter of 0.3 mm. S3. Curing and Molding: After molding, the pad block is left to stand and demolded. After pouring, the mold with the pad block is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer slurry to penetrate into the connecting pores of the inner and outer layers until the slurry initially sets. After the slurry initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the slurry finally sets. After the slurry finally sets, it is kept at constant temperature and humidity, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad block is placed in a standard curing environment with 93% humidity and a temperature of 18℃ for curing for 28 days to obtain the finished pad block. Example

[0037] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 1. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 1 for the internal support layer. Fill the core mold, vibrate at a frequency of 50 Hz for 15 s to remove air, and then use a static pressure of 4 MPa to form the core. Hold the pressure for 25 s and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Curing and Molding: After molding, the pad block is left to stand and demolded. After pouring, the mold with the pad block is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer slurry to penetrate into the connecting pores of the inner and outer layers until the slurry initially sets. After the slurry initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the slurry finally sets. After the slurry finally sets, it is kept at a constant temperature and humidity, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad block is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad block. Example

[0038] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at 60 r / min at low speed for 2 min, then stir at 120 r / min at high speed for 3 min to prepare fixed layer mix 1. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 8 mm, a porosity of 35%, and an average pore diameter of 2 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 1 for the internal support layer. Fill the core mold, first vibrate at a frequency of 50 Hz for 15 s to remove air, then use a static pressure of 4 MPa to form the core, hold the pressure for 25 s, and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 25% and an average pore diameter of 1 mm. S3. Curing and Molding: After molding, the pad block is left to stand and demolded. After pouring, the mold with the pad block is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer slurry to penetrate into the connecting pores of the inner and outer layers until the slurry initially sets. After the slurry initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the slurry finally sets. After the slurry finally sets, it is kept at a constant temperature and humidity, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad block is placed in a standard curing environment with 97% humidity and a temperature of 22℃ for curing for 28 days to obtain the finished pad block. Example

[0039] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 2. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 2 for the internal support layer. Fill the core mold, first vibrate at a frequency of 50 Hz for 15 s to remove air, then use 4 MPa pressure for static pressing and hold for 25 s. Pre-curing until initial setting is achieved to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Curing and Molding: After molding, the pad block is left to stand and demolded. After pouring, the mold with the pad block is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer slurry to penetrate into the connecting pores of the inner and outer layers until the slurry initially sets. After the slurry initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the slurry finally sets. After the slurry finally sets, it is kept at a constant temperature and humidity, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad block is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad block. Example

[0040] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 3. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 3 for the internal support layer. Fill the core mold, vibrate at a frequency of 50 Hz for 15 s to remove air, and then use a static pressure of 4 MPa to form the core. Hold the pressure for 25 s and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Curing and Molding: After molding, the pad block is left to stand and demolded. After pouring, the mold with the pad block is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer slurry to penetrate into the connecting pores of the inner and outer layers until the slurry initially sets. After the slurry initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the slurry finally sets. After the slurry finally sets, it is kept at a constant temperature and humidity, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad block is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad block. Example

[0041] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 2. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 2 for the internal support layer. Fill the core mold, first vibrate at a frequency of 50 Hz for 15 s to remove air, then use 4 MPa pressure for static pressing and hold for 25 s. Pre-curing until initial setting is achieved to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Curing and Molding: After molding, the pad block is left to stand and demolded. After pouring, the mold with the pad block is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer slurry to penetrate into the connecting pores of the inner and outer layers until the slurry initially sets. After the slurry initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the slurry finally sets. After the slurry finally sets, it is kept at a constant temperature and humidity, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad block is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad block. Example

[0042] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 3. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 3 for the internal support layer. Fill the core mold, vibrate at a frequency of 50 Hz for 15 s to remove air, and then use a static pressure of 4 MPa to form the core. Hold the pressure for 25 s and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Coaxial mold positioning: The precast porous concrete skeleton of the fixed layer and the precast porous concrete skeleton of the support layer after initial setting are coaxially fixed in the pouring mold, with a 2mm annular pouring gap reserved between the two layers. S4. Low-pressure injection interlocking molding: According to the formula, silicate cement, ultrafine silica fume, nano calcium carbonate, and expansion agent are first added to a dry powder mixer and dry-mixed at 60 r / min for 3 min to obtain a uniformly dispersed powder mixture; then water containing polycarboxylate superplasticizer, defoamer, and cellulose ether is added, and the mixture is first stirred at 50 r / min for 2 min, and then stirred at 120 r / min for 3 min. After stirring, the mixture is passed through a 2.36 mm standard square hole sieve to remove a small amount of agglomerated particles. After standing for 2 min, the mixture is allowed to naturally degas and prepare a high-flowability micro-expansion cement-based slurry 1. A 0.2 MPa low-pressure injection process is used to inject the slurry from the bottom injection port of the mold until the slurry overflows evenly from the top overflow port. Then, the injection is stopped and the injection port and overflow port are sealed. S5. Curing and Molding: After the grouting is completed, the molded pad is left to stand and then demolded. After the grouting is completed, the mold with the pad is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer grout to penetrate into the connecting pores of the inner and outer layers until the grout initially sets. After the grout initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the grout finally sets. After the grout finally sets, the temperature and humidity are kept constant, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad. Example

[0043] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 3. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 3 for the internal support layer. Fill the core mold, vibrate at a frequency of 50 Hz for 15 s to remove air, and then use a static pressure of 4 MPa to form the core. Hold the pressure for 25 s and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Coaxial mold positioning: The precast porous concrete skeleton of the fixed layer and the precast porous concrete skeleton of the support layer after initial setting are coaxially fixed in the pouring mold, with a 3mm annular pouring gap reserved between the two layers. S4. Low-pressure injection interlocking molding: According to the formula, silicate cement, ultrafine silica fume, nano calcium carbonate, and expansion agent are first added to a dry powder mixer and dry-mixed at 60 r / min for 3 min to obtain a uniformly dispersed powder mixture; then water containing polycarboxylate superplasticizer, defoamer, and cellulose ether is added, and the mixture is first stirred at 50 r / min for 2 min, and then stirred at 120 r / min for 3 min. After stirring, the mixture is passed through a 2.36 mm standard square hole sieve to remove a small amount of agglomerated particles. After standing for 2 min, the mixture is naturally degassed to prepare a high-flowability micro-expansion cement-based slurry 2. A 0.2 MPa low-pressure injection process is used to inject the slurry from the bottom injection port of the mold. After the slurry overflows evenly from the top overflow port, the injection is stopped and the injection port and overflow port are sealed. S5. Curing and Molding: After the grouting is completed, the molded pad is left to stand and then demolded. After the grouting is completed, the mold with the pad is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer grout to penetrate into the connecting pores of the inner and outer layers until the grout initially sets. After the grout initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the grout finally sets. After the grout finally sets, the temperature and humidity are kept constant, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad. Example

[0044] A method for preparing a concrete protective layer pad that prevents loosening and requires no binding includes the following preparation steps: S1. Fixed layer prefabrication: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 4 min to ensure uniform dispersion of fibers and powder. Then add water containing water-reducing agent, water-repellent agent, and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare fixed layer mix 3. Fill the outer layer molding mold, vibrate to form, and prefabricate the locking groove without binding in one piece. Place the molded mix in a standard curing environment with a temperature of 20±1℃ and a relative humidity of ≥95% for 10 h of pre-curing until the mix is ​​initially set but not fully set, to obtain a porous precast concrete skeleton with a layer thickness of 5 mm, a porosity of 30%, and an average pore diameter of 1.0 mm. S2. Prefabrication of the support layer: Weigh all powder components and add them to a dry powder mixer. Dry mix at 60 r / min for 5 min to ensure uniform dispersion of whiskers, nanomaterials, and fibers. Then add water containing water-reducing agent and foaming agent. First, stir at a low speed of 60 r / min for 2 min, then stir at a high speed of 120 r / min for 3 min to prepare porous concrete mix 3 for the internal support layer. Fill the core mold, vibrate at a frequency of 50 Hz for 15 s to remove air, and then use a static pressure of 4 MPa to form the core. Hold the pressure for 25 s and pre-cur until initial setting to obtain a porous concrete prefabricated skeleton with a porosity of 20% and an average pore diameter of 0.7 mm. S3. Coaxial mold positioning: The precast porous concrete skeleton of the fixed layer and the precast porous concrete skeleton of the support layer after initial setting are coaxially fixed in the pouring mold, with a 5mm annular pouring gap reserved between the two layers. S4. Low-pressure injection interlocking molding: According to the formula, silicate cement, ultrafine silica fume, nano calcium carbonate, and expansion agent are first added to a dry powder mixer and dry-mixed at 60 r / min for 3 min to obtain a uniformly dispersed powder mixture; then water containing polycarboxylate superplasticizer, defoamer, and cellulose ether is added, and the mixture is first stirred at 50 r / min for 2 min, and then stirred at 120 r / min for 3 min. After stirring, the mixture is passed through a 2.36 mm standard square hole sieve to remove a small amount of agglomerated particles. After standing for 2 min, the mixture is allowed to naturally degas and prepare a high-flowability micro-expansion cement-based slurry 3. A 0.3 MPa low-pressure injection process is used to inject the slurry from the bottom injection port of the mold. After the slurry overflows evenly from the top overflow port, the injection is stopped and the injection port and overflow port are sealed. S5. Curing and Molding: After the grouting is completed, the molded pad is left to stand and then demolded. After the grouting is completed, the mold with the pad is transferred to apply a constant micro-positive pressure of 0.1MPa to drive the intermediate layer grout to penetrate into the connecting pores of the inner and outer layers until the grout initially sets. After the grout initially sets, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the grout finally sets. After the grout finally sets, the temperature and humidity are kept constant, and saturated calcium hydroxide curing solution is introduced every 24 hours for pressure curing. From the 14th to the 21st day of curing, the entire pad is placed in a standard curing environment with 95% humidity and a temperature of 20℃ for curing for 28 days to obtain the finished pad.

[0045] Performance tests were conducted on Examples 1-9. The testing items and standards are as follows: 28-day compressive strength of the substrate: Using finished pad blocks as specimens, 10 pieces per group, a universal testing machine was used to load the substrate at a loading rate of 0.5 MPa / s until failure, and the compressive strength was calculated and the average value was taken; Rebar insertion integrity rate: For each group of 10 specimens, the corresponding ribbed steel bars of the same specification are pressed into the slot at a rate of 5 mm / min. No chipping, corner breaking or cracking is considered to be intact, and the integrity rate is calculated. High-frequency vibration anti-loosening pass rate: 10 specimens per group, after the steel bars are clamped to simulate the on-site working conditions, 50Hz vibrator is continuously vibrated for 60s, no displacement, loosening or falling off is qualified, and the pass rate is calculated; Bond strength between the concrete and C30 main concrete interface: A standard cubic concrete mold of 100mm×100mm×100mm is used. The concrete protective layer pad to be tested is placed with the fixed layer facing upwards at the bottom center of the mold, ensuring that the pad is in close contact with the bottom surface of the mold without gaps. In this scheme, the pads are uniformly cylindrical with an outer diameter of 60mm and a total height of 20mm. C30 commercial concrete (mixture ratio: P·O42.5 cement 400kg / m³, river sand 620kg / m³, crushed stone 1180kg / m³, water 185kg / m³, polycarboxylate superplasticizer 4.0kg / m³) was poured into the test mold and compacted using a vibrating table (50Hz vibration for 15s), and the surface was smoothed. 1.3 Ten parallel specimens were prepared for each group and left to stand in the mold for 24 hours under the same conditions; After demolding, the specimens were transferred to a standard curing room and cured for 28 days in an environment with a temperature of 20±2℃ and a relative humidity of ≥95%. During the curing period, the specimens were prevented from squeezing or colliding with each other. The testing equipment uses a 100kN universal testing machine, equipped with a 50mm diameter steel pull-out head and high-strength epoxy resin adhesive; After the specimen is removed, it is placed at room temperature for 4 hours, the surface moisture is wiped off, and the pull-out head is coaxially bonded to the support layer surface of the pad with epoxy resin adhesive. After bonding, it is left to stand at room temperature for 24 hours to ensure that the adhesive is completely cured. Perform pull-out tests according to Appendix B of JG / T483-2015, and test the ultimate pull-out load after curing under the same conditions for 28 days. Calculate the interfacial bond strength. The specimen is installed on the universal testing machine, the pull-out head is rigidly connected to the upper clamp of the testing machine, and the concrete end of the specimen is fixed to the lower clamp to ensure that the loading axis coincides with the center of the pad and there is no eccentric load. The interface was subjected to a constant loading rate of 0.5 MPa / s until significant damage occurred. The interfacial bond strength of a single specimen is calculated using the formula: σ = AF; Where: σ is the interfacial bond strength (MPa); F is the ultimate failure load (N); A is the bonding area between the pad block and the concrete (mm², which is uniformly taken as 2827mm² in this scheme).

[0046] The specific test results are shown in Table 1.

[0047] Table 1 Performance Test Table

[0048] Referring to Table 1 and Examples 1-9, the technical solution of this application, through a gradient porosity double-layer porous skeleton structure, endows the fixing slot with reversible micro-deformation capability. Combined with the three-dimensional interpenetrating rigid interlocking structure formed by the curing of the intermediate transition layer, it achieves full-cycle adaptation from "elastic yielding during installation to permanent rigid locking during service," completely solving the problems of traditional pads cracking upon insertion and loosening during vibration. The porous structure of the fixing layer forms aggregate interlocking with the main concrete, and the homogeneous cementitious system achieves hydration synergy, significantly improving interfacial bonding strength and eliminating durability defects such as interfacial debonding and harmful ion penetration. Further explanation based on Examples 1-6 and 7-9 demonstrates a significant improvement in interfacial bond strength. With optimization of the dosage of reinforcing fibers, whiskers, and nano-modified components in the mixtures of the fixing and supporting layers, the compressive and flexural strengths of the pads steadily increase. The high-frequency vibration anti-loosening pass rate in all examples is ≥90%, with optimized Examples 2 and 4-9 reaching 100%, perfectly achieving the core function of anti-loosening without binding. All performance indicators meet or even far exceed current industry standards, making it suitable for application in all scenarios of cast-in-place concrete engineering.

[0049] The present invention has been described in detail above with reference to specific embodiments and exemplary examples; however, these descriptions should not be construed as limiting the present invention. Those skilled in the art will understand that various equivalent substitutions, modifications, or improvements can be made to the technical solutions and embodiments of the present invention without departing from the spirit and scope of the invention, and all such modifications and improvements fall within the scope of the present invention. The scope of protection of the present invention is defined by the appended claims.

[0050] All publications, patent applications, patents, and other references mentioned in this specification are incorporated herein by reference. Unless otherwise defined, all technical and scientific terms used in this specification have the meanings commonly understood by those skilled in the art. In case of conflict, the definitions in this specification shall prevail.

[0051] When this specification uses the prefixes “known to those skilled in the art,” “prior art,” or similar terms to derive materials, substances, methods, steps, apparatus, or components, the objects derived from such prefixes cover those commonly used in the art at the time of this application, but also include those that are not currently commonly used but will become generally recognized in the art as suitable for similar purposes.

[0052] In the context of this specification, except where expressly stated otherwise, any matters or issues not mentioned shall apply directly to those known in the art without any modification.

Claims

1. A type of anti-loosening, non-binding concrete protective layer pad, characterized in that, It includes a fixedly connected support layer and a fixed layer. The fixed layer is provided with at least one set of fixing slots for clamping the reinforcing bars. The fixed layer includes a porous precast concrete skeleton with a thickness of 3-8 mm, a porosity of 25%-35%, and an average pore diameter of 0.5-2 mm. The support layer includes a porous precast concrete skeleton with a porosity of 15%-25% and an average pore diameter of 0.3-1 mm.

2. The anti-loosening, tie-free concrete protective layer pad according to claim 1, characterized in that, It also includes an intermediate transition layer, at least a portion of which is disposed between the support layer and the fixing layer, so that the support layer, the intermediate transition layer and the fixing layer form a seamless, layered whole.

3. The anti-loosening, non-binding concrete protective layer pad according to claim 1, characterized in that, The fixing layer comprises the following components by weight: 30-50 parts of silicate cement; 10-15 parts mineral powder; 8-12 parts fly ash; 3-5 parts silica fume; 1.0-1.5 parts of expanding agent; 3-5 parts of porous ceramsite; 1-2 parts calcium carbonate; 0.5-0.8 parts stainless steel fiber; 0.2-0.3 parts of polycarboxylate superplasticizer; 0.1-0.2 parts of organosilicon water-repellent agent; Foaming agent 0.05-0.10 parts; 10-15 parts water.

4. The anti-loosening, tie-free concrete protective layer pad according to claim 1, characterized in that, The support layer comprises the following components by weight: 42-50 parts of silicate cement; 6-8 parts silica fume; 2-3 parts of nano-calcium carbonate; 3-5 parts of wollastonite whiskers; 2-4 parts of calcium carbonate whiskers; 0.8-1.2 parts of 3mm steel fiber; 3-5 parts quartz powder; 0.5-1.0 parts of anhydrous gypsum; 0.2-0.4 parts of 3mm PVA nanofibers; 0.1-0.2 parts of hydroxylated multi-walled carbon nanotubes; 0.3-0.4 parts of polycarboxylate superplasticizer; Foaming agent 0.05-0.1 parts; 10-13 parts water.

5. The anti-loosening, non-binding concrete protective layer pad according to claim 2, characterized in that, The intermediate transition layer is prepared by curing a high-fluidity, micro-expansion cementitious slurry, which comprises the following components by weight: 45-55 parts of silicate cement; 5-10 parts silica fume; 2-5 parts of nano-calcium carbonate; 1-3 parts of expanding agent; 0.5-1.0 parts of polycarboxylate superplasticizer; Defoamer 0.1-0.2 parts; Hydroxypropyl methylcellulose ether 0.05-0.1 parts; 20-25 parts water.

6. The anti-loosening, non-binding concrete protective layer pad according to claim 5, characterized in that, The high-flowability micro-expansion cementitious slurry has an initial flowability ≥300mm and a flowability loss ≤20mm after 1 hour.

7. A method for preparing a concrete protective layer pad block for preventing loosening and requiring no binding according to any one of claims 1-6, characterized in that, The preparation steps include the following: S1. Fixed layer prefabrication: Prepare fixed layer mixture according to formula, fill it into outer layer molding mold, vibrate to form and prefabricate the non-binding locking groove in one piece, pre-curing until initial setting, to obtain outer layer porous prefabricated skeleton. S2. Precast support layer: Prepare porous concrete mix for the internal support layer according to the formula, fill it into the core mold, vibrate and press it into shape, and pre-cur it until initial setting to obtain the internal load-bearing porous precast skeleton. S3. Coaxial mold positioning: The outer porous precast skeleton and the inner load-bearing porous precast skeleton after initial setting are coaxially fixed in the pouring mold, with a 2-5mm annular pouring gap reserved between the two layers. S4. Low-pressure injection interlocking molding: Prepare high-fluidity micro-expansion cement-based slurry according to the formula, and use a low-pressure injection process of 0.2-0.3MPa to inject the slurry from the bottom injection port of the mold. Stop the injection after the slurry overflows evenly from the top overflow port, and seal the injection port and the overflow port. S5. Curing and molding: After the filling is completed, the pad block is left to stand in the mold and then demolded and cured to prepare a porous interlocking gradient functional concrete protective layer pad block.

8. The method for preparing a concrete protective layer pad block for preventing loosening and requiring no binding according to claim 7, characterized in that, The maintenance treatment includes the following maintenance steps: S1 Micro-positive pressure infiltration water retention curing: After the grouting is completed, the mold with pad blocks is transferred to apply constant micro-positive pressure, which drives the intermediate layer slurry to infiltrate into the interconnected pores of the inner and outer layers until the slurry initially sets; S2 Hydration Synchronous Gradient Temperature Curing: After the initial setting of the slurry, the pressure difference is released, and a constant micro-positive pressure of 0.1MPa is applied until the final setting of the slurry. S3 Gradient Humidity Intensity Growth Curing: After the slurry has set, maintain constant temperature and humidity, and introduce saturated calcium hydroxide curing solution every 24 hours for pressure curing. S4 Interface Enhancement and Stabilization Curing: From day 14 to day 21 of curing, place the entire pad in a standard curing environment with 93-97% humidity and 18-22℃ for 28 days to obtain the finished pad.

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