Multifunctional integrated uhcp cable trench cover plate and its forming method

Abstract

The application discloses a multifunctional integrated UHPC cable trench cover plate, which comprises, from top to bottom, a conductive functional layer, a structural bearing layer and a heat preservation and water blocking layer; the conductive functional layer comprises the following components: cement 80-120 parts, mineral powder 60-100 parts, quartz sand 100-150 parts, graphene modified carbon fiber 0.5-2 parts, conductive ceramic particles 5-15 parts, water reducing agent 0.5-1.5 parts and water 30-50 parts; the structural bearing layer comprises the following raw material components: cement 150-250 parts, silica fume 120-180 parts, fly ash cenospheres 80-120 parts, graded quartz sand 100-140 parts, end hook steel fiber 2-5 parts, flat steel fiber 1-3 parts, water reducing agent 1-2 parts, expanding agent 0.5-1 part and water 40-60 parts; and the heat preservation and water blocking layer comprises the following raw material components: cement 100-150 parts, mineral powder 80-120 parts, fly ash 60-100 parts, closed-cell ceramsite 30-60 parts, hydrophobic modified rubber particles 2-6 parts, water reducing agent 0.3-0.8 parts, permeation crystallization agent 0.2-0.6 parts and water 50-70 parts.

Description

Technical Field

[0001] This invention belongs to the technical field of cable trench covers, and particularly relates to a multifunctional integrated UHPC cable trench cover and its molding method. Background Technology

[0002] Ultra-high performance concrete (UHPC) has been widely used in bridges, building decoration, and municipal facilities due to its excellent mechanical properties and durability. As an important component of infrastructure, cable trench covers bear the dual effects of vehicle loads and environmental erosion over long periods of time, and their service performance directly affects line safety and operation and maintenance costs.

[0003] In existing technologies, such as the Chinese invention patent CN112047696B, a tunnel cable trench RPC cover plate is disclosed. This cover plate, through the incorporation of modified steel fibers and rubber particles, improves its bending and seepage resistance to a certain extent. However, this technology still has the following shortcomings: the material system it uses is a homogeneous design, meaning the entire cover plate has the same composition and properties in the thickness direction. This design leads to a limited function of the cover plate, providing only basic structural load-bearing capacity and failing to meet the diverse needs of complex service environments.

[0004] For example, in cold regions of northern my country, after snow and ice accumulate on the surface of cable trench covers in winter, the lack of active de-icing capabilities usually necessitates manual knocking or the application of de-icing agents for cleaning. This not only results in high maintenance costs and low efficiency, but the chloride ions in the de-icing agents also accelerate the corrosion of the steel bars or fibers inside the covers, further shortening their service life. Furthermore, homogeneous design means that the material properties of each part of the cover are designed according to the most unfavorable working conditions. This prevents the separate optimization of differentiated functional requirements such as wear-resistant and anti-slip surface layer, high-strength load-bearing middle layer, and impermeable and insulating bottom layer, leading to low material utilization and poor economic efficiency. Summary of the Invention

[0005] To address the problems in the prior art, the present invention proposes the following technical solution: The present invention provides a multifunctional integrated UHPC cable trench cover, which includes a conductive functional layer, a structural bearing layer and a heat insulation and water-blocking layer connected from top to bottom; The conductive functional layer comprises the following raw material components in parts by weight: 80-120 parts cement, 60-100 parts mineral powder, 100-150 parts quartz sand, 0.5-2 parts graphene-modified carbon fiber, 5-15 parts conductive ceramic particles, 0.5-1.5 parts water-reducing agent, and 30-50 parts water. The structural bearing layer comprises the following raw material components in parts by weight: 150-250 parts cement, 120-180 parts silica fume, 80-120 parts fly ash microspheres, 100-140 parts graded quartz sand, 2-5 parts hooked steel fibers, 1-3 parts straight steel fibers, 1-2 parts water-reducing agent, 0.5-1 part expansion agent, and 40-60 parts water. The thermal insulation and water-blocking layer comprises the following raw material components in parts by weight: 100-150 parts cement, 80-120 parts mineral powder, 60-100 parts fly ash, 30-60 parts closed-cell ceramsite, 2-6 parts hydrophobic modified rubber particles, 0.3-0.8 parts water-reducing agent, 0.2-0.6 parts penetrating crystallizer, and 50-70 parts water.

[0006] As a preferred embodiment of the above technical solution, the thickness of the conductive functional layer is 8mm-15mm, the thickness of the structural bearing layer is 25mm-40mm, and the thickness of the thermal insulation and water-blocking layer is 10mm-20mm.

[0007] As a preferred embodiment of the above technical solution, the graphene-modified carbon fiber is a PAN-based carbon fiber with graphene oxide grafted onto its surface, and its fiber diameter is 5μm-10μm and its length is 3mm-6mm; the conductive ceramic particles are titanium carbide or zirconium carbide particles with a particle size of 0.5mm-2mm.

[0008] As a preferred embodiment of the above technical solution, the length of the hook-shaped steel fiber is 12mm-14mm, the diameter is 0.18mm-0.22mm, and the tensile strength is ≥2500MPa; the length of the straight steel fiber is 5mm-8mm, the diameter is 0.10mm-0.15mm, and the tensile strength is ≥2800MPa.

[0009] As a preferred embodiment of the above technical solution, the closed-cell ceramsite has a particle size of 1mm-3mm, a compressive strength ≥8MPa, and a water absorption rate ≤5%; the hydrophobic modified rubber granules are obtained from waste tire rubber through surface treatment with a silane coupling agent, and the particle size is 20-60 mesh. As a preferred embodiment of the above technical solution, the graded quartz sand is composed of quartz sand of 20-40 mesh, 40-70 mesh and 70-140 mesh mixed in a mass ratio of 3:5:2; the fly ash microspheres have a particle size of 5μm-15μm and a spherical particle content of ≥95%.

[0010] As a preferred embodiment of the above technical solution, the expanding agent is a calcium sulfoaluminate-calcium oxide composite expanding agent; the penetrating crystallizer is a composite of sodium silicate and lithium carbonate in a mass ratio of 2:1.

[0011] The molding method for multifunctional integrated UHPC cable trench covers includes the following steps: S1. Prepare conductive functional layer slurry, structural load-bearing layer slurry and thermal insulation and water-blocking layer slurry respectively. S2. The layered pouring method is adopted. First, the thermal insulation and water-blocking slurry is injected into the bottom of the mold and compacted. Then, the structural bearing layer slurry is poured on it. Finally, the conductive functional layer slurry is poured. The thickness of each layer is controlled during the pouring process. S3. Place the mold after casting on a vibrating table and vibrate it for 3-5 minutes at an amplitude of 0.3mm-0.5mm and a frequency of 50Hz-60Hz to compact it. S4. After compaction, let the specimen stand at room temperature for 4-6 hours, then place it in the primary curing chamber and cure it in the mold for 24 hours in an environment with a temperature of 20℃-25℃ and a relative humidity of ≥95%. S5. After demolding, the specimen is moved into the steam curing chamber and heated to 80℃-90℃ at a rate of 15℃ / h. It is then kept at a constant temperature for 48h and then cooled to room temperature at a rate of 10℃ / h. S6. After curing, the cover plate is cured for another 28 days under standard curing conditions (temperature 20±2℃, humidity ≥95%) to obtain the finished product.

[0012] As a preferred embodiment of the above technical solution, in step S1, the stirring speed of the conductive functional layer slurry is 200 r / min-300 r / min, and the stirring time is 10 min-15 min; the stirring speed of the structural bearing layer slurry is 150 r / min-250 r / min, and the stirring time is 20 min-30 min; the stirring speed of the thermal insulation and water-blocking layer slurry is 180 r / min-280 r / min, and the stirring time is 15 min-25 min.

[0013] As a preferred embodiment of the above technical solution, in step S3, during layered pouring, each layer is tamped after pouring, and the pouring interval between two adjacent layers does not exceed 20 minutes to ensure the bonding strength of the interlayer interface.

[0014] The beneficial effects of this invention are as follows: (1) The present invention integrates three functions—active electrothermal de-icing, high-strength structural bearing, and bottom anti-seepage insulation—by setting a three-layer gradient structure from top to bottom: a conductive functional layer, a structural bearing layer, and a thermal insulation and water-blocking layer. Each layer has a clear division of labor and works together to give the cover plate intelligent active de-icing capability while taking into account structural safety and service durability. It solves the technical problem of the single function of traditional homogeneous cover plates and is especially suitable for cold and humid environments.

[0015] (2) The present invention uses graphene-modified carbon fiber and conductive ceramic particles to form a dual conductive pathway of "fiber-particle" in the conductive functional layer. The fiber constructs a long-range conductive skeleton, and the particles fill the conductive blind area between the fibers. The two complement each other to make the conductive pathway more continuous and stable. Excellent conductivity can be obtained at low dosage, realizing low-pressure safe de-icing and avoiding the chemical corrosion of the cover material caused by traditional de-icing agent application.

[0016] (3) The present invention adopts a hybrid system of end-hook steel fibers and straight steel fibers in the structural bearing layer. The end-hook steel fibers control the propagation of macroscopic cracks through the end anchoring effect, while the straight steel fibers suppress the initiation of microscopic cracks through dense distribution. The two complement each other in terms of scale and function, and work together to significantly improve the flexural strength and toughness index, effectively overcoming the problem of high brittleness of ordinary UHPC.

[0017] (4) In this invention, the closed-cell ceramic particles in the heat insulation and water-blocking layer play the role of physical heat insulation and blocking capillary channels. The hydrophobic modified rubber particles give the matrix hydrophobic properties and absorb the temperature difference deformation stress. The penetrating crystallizer generates insoluble crystals when it comes into contact with water to block the pore channels. The three together form a multi-layer anti-permeability mechanism of "heat insulation + hydrophobicity + crystallization blocking", which significantly improves the anti-permeability level. Detailed Implementation

[0018] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0019] Examples 1-3

[0020] The components and parameters of Examples 1-3 are shown in Tables 1, 2 and 3: Table 1: Weight data of the three-layer structure in each embodiment (unit: parts)

[0021] Table 1 Table 2: Key Raw Material Parameter Values ​​for Each Embodiment

[0022] Table 2 Table 3: Layer thickness of each embodiment

[0023] Table 3 Examples 1-3 were prepared and shaped according to the steps in Examples 1-3 respectively to obtain finished cover plates and samples.

[0024] Preparation Example 1 S1 slurry preparation: Weigh the raw materials for each layer according to the proportions in Table 1 and Table 2. Stir the conductive functional layer slurry at 200 r / min for 10 min, the structural bearing layer slurry at 150 r / min for 20 min, and the thermal insulation and water-blocking layer slurry at 180 r / min for 15 min to obtain uniform slurries. S2 Layered Casting: In the steel mold coated with release agent, first cast the thermal insulation and water-blocking layer, tamp and vibrate to compact; after a 15-minute interval, cast the structural load-bearing layer and vibrate to compact; after another 15-minute interval, cast the conductive functional layer, and control the thickness of each layer according to Table 3. S3 Vibration Compaction: Place the mold on a vibration table, with an amplitude of 0.3 mm and a frequency of 50 Hz, and vibrate for 3 minutes to compact. S4 static setting and initial curing with mold: After static setting at room temperature for 4 hours, move to the initial curing room (temperature 20℃, relative humidity ≥95%) and cure with mold for 24 hours; S5 Demolding and Steam Curing: After demolding, move the mold into the steam curing chamber, raise the temperature to 80℃ at 15℃ / h, keep the temperature constant for 48h, and then lower the temperature to room temperature at 10℃ / h. S6 Standard Curing: After removal, cure in a standard curing room (temperature 20±2℃, relative humidity ≥95%) for 28 days to obtain the finished product.

[0025] Preparation Example 2 S1 slurry preparation: Weigh the raw materials for each layer according to the proportions in Table 1 and Table 2. Stir the conductive functional layer slurry at 300 r / min for 15 min, the structural bearing layer slurry at 250 r / min for 30 min, and the thermal insulation and water-blocking layer slurry at 280 r / min for 25 min to obtain uniform slurries. S2 Layered Casting: In the steel mold coated with release agent, first cast the thermal insulation and water-blocking layer, tamp and vibrate to compact; after a 20-minute interval, cast the structural load-bearing layer and vibrate to compact; after another 20-minute interval, cast the conductive functional layer, and control the thickness of each layer according to Table 3. S3 Vibration Compaction: Place the mold on a vibration table, with an amplitude of 0.5 mm and a frequency of 60 Hz, and vibrate for 5 minutes to compact. S4 static setting and initial curing with mold: After static setting at room temperature for 6 hours, move to the initial curing room (temperature 25℃, relative humidity ≥95%) and cure with mold for 24 hours; S5 Demolding and Steam Curing: After demolding, move the mold into the steam curing chamber, raise the temperature to 90℃ at 15℃ / h, keep the temperature constant for 48h, and then lower the temperature to room temperature at 10℃ / h. S6 Standard Curing: After removal, cure in a standard curing room (temperature 20±2℃, relative humidity ≥95%) for 28 days to obtain the finished product.

[0026] Preparation Example 3 S1 slurry preparation: Weigh the raw materials of each layer according to the proportions in Table 1. Stir the conductive functional layer and the heat insulation and water-blocking layer at a speed of 250 r / min for 15 min, and stir the structural bearing layer at a speed of 200 r / min for 25 min to obtain uniform slurries. S2 Layered Casting: In the steel mold coated with release agent, first cast the thermal insulation and water-blocking layer, tamp and vibrate to compact; after a 10-minute interval, cast the structural load-bearing layer and vibrate to compact; after another 10-minute interval, cast the conductive functional layer, and control the thickness of each layer according to Table 3. S3 Vibration Compaction: Place the mold on a vibration table, with an amplitude of 0.4 mm and a frequency of 55 Hz, and vibrate for 4 minutes to compact. S4 static setting and initial curing with mold: After static setting at room temperature for 5 hours, move to the initial curing room (temperature 22℃, relative humidity ≥95%) and cure with mold for 24 hours; S5 Demolding and Steam Curing: After demolding, move the mold into the steam curing chamber, raise the temperature to 85℃ at 15℃ / h, keep the temperature constant for 48h, and then lower the temperature to room temperature at 10℃ / h. S6 Standard Curing: After removal, cure in a standard curing room (temperature 20±2℃, relative humidity ≥95%) for 28 days to obtain the finished product.

[0027] Comparative Example 1 This comparative example only uses a structural load-bearing layer and a thermal insulation and water-blocking layer, without a conductive functional layer; the rest is the same as in Example 2.

[0028] Comparative Example 2 In this comparative example, only 4 parts of hooked steel fibers were added to the structural bearing layer, with no straight steel fibers. The rest was the same as in Example 2.

[0029] Comparative Example 3 This comparative example only includes a conductive functional layer and a structural support layer, without a thermal insulation and water-blocking layer; otherwise, it is the same as Example 2.

[0030] Performance testing The performance of the cover plate samples of Examples 1-3 and Comparative Examples 1-3 prepared according to the steps of Preparation Examples 1-3 were tested, and the results are shown in Table 4.

[0031] Table 4: Performance test results of each embodiment and comparative example

[0032] Table 4 As shown in Table 3, Examples 1-3 all exhibit excellent conductive ice-melting capabilities, while Comparative Example 1 lacks a conductive functional layer and cannot achieve electrothermal ice-melting. The flexural strength and toughness index I5 of Example 2 are significantly better than those of Comparative Example 2, which uses only a single fiber, demonstrating the significant synergistic reinforcing effect of the hybrid fibers with hooked and straight ends. The impermeability grades of Examples 1-3 all reach P12 or higher, while Comparative Example 3 lacks a thermal insulation and water-blocking layer, resulting in an impermeability grade that drops to P8. This indicates that the combined effect of closed-cell ceramic particles, hydrophobic modified rubber particles, and penetrating crystallizer effectively improves the impermeability performance of the cover plate.

[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it.

Claims

1. A multi-functional integrated UHPC cable trench cover, characterized in that, It includes, from top to bottom, a conductive functional layer, a structural support layer, and a thermal insulation and water-blocking layer; The conductive functional layer comprises the following raw material components in parts by weight: 80-120 parts cement, 60-100 parts mineral powder, 100-150 parts quartz sand, 0.5-2 parts graphene-modified carbon fiber, 5-15 parts conductive ceramic particles, 0.5-1.5 parts water-reducing agent, and 30-50 parts water. The structural bearing layer comprises the following raw material components in parts by weight: 150-250 parts cement, 120-180 parts silica fume, 80-120 parts fly ash microspheres, 100-140 parts graded quartz sand, 2-5 parts hooked steel fibers, 1-3 parts straight steel fibers, 1-2 parts water-reducing agent, 0.5-1 part expansion agent, and 40-60 parts water. The thermal insulation and water-blocking layer comprises the following raw material components in parts by weight: 100-150 parts cement, 80-120 parts mineral powder, 60-100 parts fly ash, 30-60 parts closed-cell ceramsite, 2-6 parts hydrophobic modified rubber particles, 0.3-0.8 parts water-reducing agent, 0.2-0.6 parts penetrating crystallizer, and 50-70 parts water.

2. The multifunctional integrated UHPC cable trench cover according to claim 1, characterized in that, The thickness of the conductive functional layer is 8mm-15mm, the thickness of the structural bearing layer is 25mm-40mm, and the thickness of the thermal insulation and water-blocking layer is 10mm-20mm.

3. The multifunctional integrated UHPC cable trench cover according to claim 1, characterized in that, The graphene-modified carbon fiber is a PAN-based carbon fiber with graphene oxide grafted onto its surface, and its fiber diameter is 5μm-10μm and its length is 3mm-6mm; the conductive ceramic particles are titanium carbide or zirconium carbide particles with a particle size of 0.5mm-2mm.

4. The multifunctional integrated UHPC cable trench cover according to claim 1, characterized in that, The hooked steel fiber has a length of 12mm-14mm, a diameter of 0.18mm-0.22mm, and a tensile strength ≥2500MPa; the straight steel fiber has a length of 5mm-8mm, a diameter of 0.10mm-0.15mm, and a tensile strength ≥2800MPa.

5. The multifunctional integrated UHPC cable trench cover according to claim 1, characterized in that, The closed-cell ceramsite has a particle size of 1mm-3mm, a cylinder compressive strength ≥8MPa, and a water absorption rate ≤5%; the hydrophobic modified rubber particles are obtained by surface treatment of waste tire rubber with silane coupling agent, and the particle size is 20-60 mesh.

6. The multifunctional integrated UHPC cable trench cover according to claim 1, characterized in that, The graded quartz sand is composed of quartz sand of 20-40 mesh, 40-70 mesh and 70-140 mesh in a mass ratio of 3:5:2; the fly ash microspheres have a particle size of 5μm-15μm and a spherical particle content of ≥95%.

7. The multifunctional integrated UHPC cable trench cover according to claim 1, characterized in that, The expanding agent is a calcium sulfoaluminate-calcium oxide composite expanding agent; the penetrating crystallizer is a complex of sodium silicate and lithium carbonate in a mass ratio of 2:

1.

8. A method for molding a multifunctional integrated UHPC cable trench cover, characterized in that: Specifically, the steps include the following: S1. Prepare conductive functional layer slurry, structural load-bearing layer slurry and thermal insulation and water-blocking layer slurry respectively. S2. The layered pouring method is adopted. First, the thermal insulation and water-blocking slurry is injected into the bottom of the mold and compacted. Then, the structural bearing layer slurry is poured on it. Finally, the conductive functional layer slurry is poured. The thickness of each layer is controlled during the pouring process. S3. Place the mold after casting on a vibrating table and vibrate it for 3-5 minutes at an amplitude of 0.3mm-0.5mm and a frequency of 50Hz-60Hz to compact it. S4. After compaction, let the specimen stand at room temperature for 4-6 hours, then place it in the primary curing chamber and cure it in the mold for 24 hours in an environment with a temperature of 20℃-25℃ and a relative humidity of ≥95%. S5. After demolding, the specimen is moved into the steam curing chamber and heated to 80℃-90℃ at a rate of 15℃ / h. It is then kept at a constant temperature for 48h and then cooled to room temperature at a rate of 10℃ / h. S6. After curing, the cover plate is cured for another 28 days under standard curing conditions (temperature 20±2℃, humidity ≥95%) to obtain the finished product.

9. The method for forming a multifunctional integrated UHPC cable trench cover according to claim 8, characterized in that, In step S1, the stirring speed of the conductive functional layer slurry is 200 r / min-300 r / min, and the stirring time is 10 min-15 min; the stirring speed of the structural bearing layer slurry is 150 r / min-250 r / min, and the stirring time is 20 min-30 min; the stirring speed of the thermal insulation and water-blocking layer slurry is 180 r / min-280 r / min, and the stirring time is 15 min-25 min.

10. The method for forming a multifunctional integrated UHPC cable trench cover according to claim 8, characterized in that, In step S3, during layered pouring, each layer is tamped after pouring, and the pouring interval between adjacent layers does not exceed 20 minutes to ensure the bonding strength of the interlayer interface.

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