Permeable concrete porosity gradient control process

Abstract

The invention relates to the technical field of concrete engineering, in particular to a pervious concrete porosity gradient control process. The method mainly comprises the steps of early-stage material preparation and testing, pore gradient layered design, test piece manufacturing, layered pouring process, vacuum adsorption assistance, interface treatment between layers, gradient pore control technology, maintenance and surface treatment, pore and performance detection and the like. The problem of non-uniform porosity distribution is solved through the hierarchical design of the porosity gradient and the accurate control of the porosity connectivity; through a layered design and a gradient pore control technology, the strength and the water permeability are both considered; through interface treatment between layers and use of basalt fibers, the interlayer bonding strength is improved; through surface treatment and silane impregnation, the risk of surface pollution and blockage is reduced. Therefore, the method has the advantages that the porosity distribution uniformity is improved, the strength and the water permeability are both considered, the interlayer bonding strength is improved, and surface pollution and blockage are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete engineering, and particularly relates to a process for controlling the pore gradient of permeable concrete. Background Art

[0002] Permeable concrete is mainly composed of coarse aggregate and cement, and the aggregate is bonded together by a cementitious paste to form a porous structure, which has relatively high water permeability. The traditional mix design of permeable concrete mainly uses two parameters: the water-binder ratio and the porosity. Usually, the porosity is controlled between 15% and 30%, and the water-cement ratio is between 0.25 and 0.40. However, this simple mix design method has some limitations.

[0003] Related research shows that the main factors affecting the permeability and mechanical properties of permeable concrete include porosity, aggregate characteristics, water-cement ratio, and the properties of cementitious materials. Relying solely on the two parameters of water-binder ratio and porosity for mix design is difficult to fully meet the performance requirements of permeable concrete. This design method cannot accurately control the distribution and connectivity of pores, resulting in difficulty in simultaneously achieving ideal states for water permeability and strength performance.

[0004] In addition, the traditional construction technology of permeable concrete also faces some challenges. Due to the special nature of the pore structure, conventional pouring and vibration methods are difficult to ensure the uniformity and density of the concrete. This not only increases the construction difficulty but also may lead to unstable quality of the finished product, affecting the overall performance and durability of permeable concrete.

[0005] In the prior art, permeable concrete often has the following problems: uneven porosity distribution, resulting in large differences in water permeability in local areas; it is difficult to balance strength and water permeability, and high water permeability often comes with a decrease in strength; insufficient interlayer bonding strength, affecting the stability of the overall structure; the surface is easily contaminated and blocked, reducing the long-term use effect.

[0006] In view of the above problems, the prior art urgently needs to be improved. Summary of the Invention

[0007] The purpose of the present invention is to provide a process for controlling the pore gradient of permeable concrete, which has the advantages of improving the uniformity of porosity distribution, balancing strength and water permeability, enhancing the interlayer bonding strength, and reducing surface contamination and blockage.

[0008] To achieve the above invention purpose, the technical solution adopted by the present invention is as follows:

[0009] It mainly includes the following steps:

[0010] Step 1: Preparation and testing of materials in the early stage, including grading and screening of the aggregate and pretreatment.

[0011] Step 2: Pore gradient layering design, with the porosity increasing from the bottom layer to the surface layer, that is, the upper layer has larger aggregate particle sizes, larger pore diameters, faster water permeability, while the lower layer has relatively smaller particles, smaller pore diameters, relatively slower water permeability, and higher strength;

[0012] Step 3: Specimen fabrication. First, coat the inner wall of the mixer with a slurry of the same mix ratio, then add coarse aggregates and cementitious materials and stir for 2 minutes. After stirring evenly, add water-reducing agent and 50% of the remaining water and continue to stir for 1 minute, then add the remaining water and stir for 1 minute, and finally add fibers and stir for 2 minutes;

[0013] Step 4: Layered pouring process, including layer-by-layer placing of materials and vibration compaction;

[0014] Step 5: Vacuum adsorption assistance. After pouring, suck out the excess slurry through negative pressure to precisely control the pore connectivity;

[0015] Step 6: Interface treatment between layers, including roughening and spraying of interface agent;

[0016] Step 7: Gradient pore control technology;

[0017] Step 8: Curing and surface treatment, including moisture curing and silane impregnation;

[0018] Step 9: Pore and property detection.

[0019] Further, the present application also proposes that the roughening includes using a wire brush or sandblasting to treat the surface before the final setting of the lower layer or within 1 hour after pouring to form roughness.

[0020] Further, the present application also proposes that the roughness Ra ≥ 0.5 mm.

[0021] Further, the present application also proposes that the interface agent is neat cement slurry, and the neat cement slurry is applied by spraying process.

[0022] Further, the present application also proposes that a part of basalt fibers is sprinkled before pouring the upper layer, which helps to connect the upper and lower layers.

[0023] Further, the present application also proposes that the gradient pore control technology includes directional vibration. The directional vibration includes lower layer vibration and upper layer vibration. The lower layer vibration uses an inserted high-frequency vibrator, 50 Hz, to prevent the slurry from floating up. The upper layer vibration uses a plate vibrator, with a low frequency of 30 Hz, to quickly level the surface and avoid damaging the lower layer structure. The lower layer has a higher frequency, which is beneficial for compaction, and the upper layer has a lower frequency, which is beneficial for maintaining large pores.

[0024] Further, the present application also proposes that the porosity of the upper layer is 25% to 35%, and the porosity of the lower layer is 10% to 15%.

[0025] Furthermore, the present application also proposes that the compressive strength of the upper layer is 15 to 20 MPa, and the compressive strength of the lower layer is 20 to 30 MPa.

[0026] Furthermore, the present application also proposes that the core material includes granite coarse aggregate, cement, basalt fiber, silica fume, fly ash, water reducing agent and water.

[0027] As an improvement, the beneficial effects of the present invention are:

[0028] The present application provides a permeable concrete pore gradient control process, which mainly includes the steps of preliminary material preparation and testing, pore gradient layered design, specimen preparation, layered casting process, vacuum adsorption assistance, interface treatment between layers, gradient pore control technology, maintenance and surface treatment, and pore and performance testing. The problem of uneven porosity distribution is solved by pore gradient layered design and precise control of pore connectivity; the balance between strength and permeability is achieved through layered design and gradient pore control technology; the interlayer bonding strength is improved through interface treatment between layers and the use of basalt fiber; the risk of surface contamination and clogging is reduced through surface treatment and silane impregnation. Therefore, the present application has the advantages of improving the uniformity of porosity distribution, balancing strength and permeability, improving interlayer bonding strength, and reducing surface contamination and clogging. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 A flow chart of a pore gradient control process for permeable concrete according to the present invention;

[0030] Figure 2 Schematic diagram of the chemical composition of silica fume and fly ash in the present invention;

[0031] Figure 3 This is a schematic diagram of the performance indicators of basalt fiber in the present invention;

[0032] Figure 4 It is a schematic diagram of the performance indicators of the upper layer and the lower layer of the present invention;

[0033] Figure 5 This is a schematic diagram of the molding of the upper layer of permeable concrete of the present invention;

[0034] Figure 6 This is a schematic diagram of the lower layer concrete forming process of the present invention;

[0035] Figure 7 This is a schematic diagram of the effect of the basalt fiber of the present invention on the slurry or interface connection; DETAILED DESCRIPTION

[0036] In order to make the contents of the present invention more clearly understood, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention.

[0037] Permeable concrete is mainly composed of coarse aggregates and cement. The aggregate is bonded together by a cementitious paste to form a porous structure, which has a large water permeability. The mix proportion design of permeable concrete uses two parameters: water-binder ratio and porosity. Usually, the porosity is 15% to 30%, and the water-cement ratio is 0.25 to 0.40. Relevant research shows that the main factors affecting the permeability and mechanical properties of permeable concrete are porosity, aggregate, water-cement ratio, and cementitious materials. However, it is difficult to meet the performance requirements of permeable concrete with only the mix proportion of these two parameters, and the construction difficulty is relatively high.

[0038] The pore gradient control process of permeable concrete mainly includes the following steps: preliminary material preparation and testing, including grading and screening of the aggregate gradation and pretreatment; pore gradient layered design, with the porosity increasing from the bottom layer to the surface layer, that is, the aggregate particle size in the upper layer is large, the pore size is large, and the water permeability is fast, while the particles in the lower layer are relatively small, the pore size is small, the water permeability is relatively slow, and the strength is higher; specimen production, adding silica fume fiber; layered pouring process, including layer-by-layer material placement and vibration compaction; vacuum adsorption assistance, sucking out the excess slurry through negative pressure after pouring to precisely control the pore connectivity; interface treatment between layers, including roughening and spraying of interface agents; gradient pore control technology; curing and surface treatment, including moisture conservation curing and silane impregnation; pore and performance detection.

[0039] The present invention aims to solve the problem that it is difficult to balance the permeability and mechanical properties of permeable concrete. Through preliminary material preparation and testing, it is ensured that the aggregate gradation and pretreatment meet the requirements. The pore gradient layered design enables the porosity of the bottom layer and the surface layer to gradually increase, thereby achieving the balance between water permeability and strength. The specimen production improves the toughness and durability of the concrete by adding silica fume fiber. The layered pouring process ensures the density and pore structure of each layer through layer-by-layer material placement and vibration compaction. The vacuum adsorption assistance technology precisely controls the pore connectivity by sucking out the excess slurry through negative pressure after pouring. The interface treatment between layers enhances the interlayer bonding force through roughening and spraying of interface agents. The gradient pore control technology realizes the pore structure of different layers through directional vibration. The curing and surface treatment ensure the durability and surface performance of the concrete through moisture conservation curing and silane impregnation. Finally, the effect of the process is verified through pore and performance detection.

[0040] The implementation environment of the permeable concrete pore gradient control process includes aggregate, cement, basalt fiber, silica fume, fly ash, water reducer and water. The gradation and pretreatment of the aggregate are the basis for ensuring a reasonable pore structure. The performance of the concrete is improved by incorporating silica fume fiber during specimen production. The layered pouring process ensures the density and pore structure of each layer through layer-by-layer material placement and vibration compaction. The vacuum adsorption assistance technology precisely controls the connectivity of pores by sucking out excess slurry through negative pressure after pouring. The interface treatment between layers enhances the interlayer bonding force through roughening and spraying of interface agents. The gradient pore control technology realizes the pore structures of different layers through directional vibration. The curing and surface treatment ensure the durability and surface performance of the concrete through moisture conservation curing and silane impregnation.

[0041] The preliminary material preparation and testing include the gradation classification screening and pretreatment of the aggregate. For the pore gradient layered design, the porosity gradually increases from the bottom layer to the surface layer. The aggregate particle size in the upper layer is large, the pore diameter is large, and the water permeability is fast. The particles in the lower layer are relatively small, the pore diameter is small, the water permeability is relatively slow, and the strength is higher. The toughness and durability of the concrete are improved by incorporating silica fume fiber during specimen production. The layered pouring process ensures the density and pore structure of each layer through layer-by-layer material placement and vibration compaction. The vacuum adsorption assistance technology precisely controls the connectivity of pores by sucking out excess slurry through negative pressure after pouring. The interface treatment between layers enhances the interlayer bonding force through roughening and spraying of interface agents. The gradient pore control technology realizes the pore structures of different layers through directional vibration. The curing and surface treatment ensure the durability and surface performance of the concrete through moisture conservation curing and silane impregnation. The pore and performance detection verifies the effectiveness of the process by detecting the porosity and mechanical properties.

[0042] Compared with the prior art, through a multi-step process flow, the present invention systematically solves the problem that it is difficult to balance the permeability and mechanical properties of permeable concrete in multiple aspects, including material preparation, pore gradient design, specimen production, layered pouring, vacuum adsorption, interface treatment, gradient pore control, curing and surface treatment, and performance detection. Through technical means such as directional vibration, vacuum adsorption and interface treatment, it ensures that the permeable concrete has a reasonable pore structure, strong interlayer bonding force, and excellent water permeability and mechanical properties at the same time.

[0043] The pore gradient control process of the permeable concrete of the present invention ensures that the gradation and pretreatment of the aggregate meet the requirements through preliminary material preparation and testing. The pore gradient layered design enables the porosity of the bottom layer and the surface layer to gradually increase, thereby achieving the balance between water permeability and strength. The toughness and durability of the concrete are improved by adding silica fume fibers during specimen production. The layered pouring process ensures the density and pore structure of each layer through layer-by-layer feeding and vibration compaction. The vacuum adsorption assistance technology precisely controls the connectivity of the pores by sucking out the excess slurry through negative pressure after pouring. The interface treatment between layers enhances the interlayer bonding force through roughening and spraying the interface agent. The gradient pore control technology realizes the pore structures of different layers through directional vibration. The curing and surface treatment ensure the durability and surface performance of the concrete through moisture conservation curing and silane impregnation. Finally, the effect of the process is verified through pore and performance detection.

[0044] Further, the present application also proposes that, before the final setting of the lower layer or within 1 hour after pouring, the surface is treated with a wire brush or sandblasting to form roughness.

[0045] The purpose of this technical solution is to improve the bonding strength between layers and avoid the interlayer peeling phenomenon caused by a smooth interface. By treating the surface with a wire brush or sandblasting before the final setting of the lower layer or within 1 hour after pouring, a certain roughness can be formed, thereby increasing the frictional force and mechanical biting force of the interface.

[0046] Specifically, the roughening treatment can be achieved in various ways, such as manually brushing with a wire brush or sandblasting with sandblasting equipment. The wire brush treatment is simple and easy to implement and is suitable for small areas or irregular regions; the sandblasting treatment has high efficiency and is suitable for large-area construction. No matter which method is adopted, it is necessary to ensure that it is completed before the final setting of the lower layer or within 1 hour after pouring to ensure the treatment effect.

[0047] Thus, by increasing the interface roughness, the interlayer bonding force can be effectively improved, and the overall structural strength and durability of the permeable concrete can be enhanced. Compared with the prior art, this solution significantly improves the performance of the permeable concrete while ensuring the simplicity of construction.

[0048] Further, the present application also proposes that the roughness Ra≥0.5mm.

[0049] The pore gradient control process of the permeable concrete involves multiple steps, including material preparation, pore gradient design, specimen production, layered pouring, vacuum adsorption assistance, interface treatment, gradient pore control, curing and surface treatment, and pore and performance detection. Through these steps, it aims to achieve a gradual change in porosity from the upper layer to the lower layer, thereby optimizing water permeability and mechanical properties.

[0050] Specifically, a roughness Ra≥0.5mm is achieved by using a wire brush or sandblasting to treat the surface before the final setting of the lower layer or within 1 hour after pouring. This treatment method can effectively increase the roughness of the interface, enhance the bonding force between the upper and lower layers, and thus improve the stability and durability of the overall structure. Both wire brushing and sandblasting are common surface treatment methods, which are characterized by simple operation and remarkable effects.

[0051] By adopting the interface treatment method with a roughness Ra≥0.5mm, this application can significantly improve the interlayer bonding force of the permeable concrete, enhance the overall stability of the structure, and ensure the durability and reliability in practical applications. Compared with the prior art, the technical solution of this application has significant advantages in controlling the pore gradient and improving the mechanical properties.

[0052] Furthermore, this application also proposes that the interface agent is cement slurry, and the cement slurry is applied by spraying.

[0053] Technical solution explanation:

[0054] In this application, the interface agent is selected as cement slurry and treated by spraying. As an interface agent, the cement slurry can effectively fill the pores between the concrete layers, increase the interlayer bonding force, and prevent the occurrence of interlayer peeling and cracks. The spraying process can ensure that the cement slurry is evenly distributed on the concrete surface, further improving the effect of interface treatment.

[0055] Using cement slurry as the interface agent means using pure cement slurry between the concrete layers. This material has high bonding performance and strength. The spraying process refers to evenly spraying the cement slurry on the concrete surface through a spraying device. This method can ensure the uniform distribution of the cement slurry, making the interlayer bonding more firm. Specifically, the spraying process can be achieved by a hand-held sprayer or a mechanical spraying device to ensure the convenience and uniformity of the operation.

[0056] By using cement slurry as the interface agent and the spraying process for interface treatment, this application solves the problem of insufficient interlayer bonding force in traditional construction methods, significantly improves the bonding strength between concrete layers, and reduces the risk of interlayer peeling and cracks. Compared with the prior art, this method is simple to operate and has remarkable effects, which helps to improve the overall performance and durability of the permeable concrete.

[0057] Furthermore, this application also proposes that spreading some basalt fibers before pouring the upper layer helps the connection between the upper and lower layers.

[0058] During the construction of permeable concrete, the design of porosity and aggregate ratio is crucial. The traditional design of permeable concrete ratio mainly relies on two parameters, namely water-cement ratio and porosity. Usually, the porosity is 15% to 30%, and the water-cement ratio is 0.25 to 0.40. However, it is difficult to meet the performance requirements of permeable concrete only relying on these two parameters, and the construction difficulty is relatively high. The solution proposed in this application aims to solve this problem by spreading part of basalt fiber before pouring the upper layer to enhance the connection between the upper and lower layers.

[0059] Basalt fiber is a high-strength fiber material with excellent mechanical properties and durability. Spreading basalt fiber on the surface of the lower-layer concrete can effectively enhance the bonding strength between the upper and lower layers of concrete and avoid the separation phenomenon between layers. Specifically, after the lower-layer concrete is poured and initially solidified, basalt fiber is evenly spread, and then the upper-layer concrete is poured. Basalt fiber forms a bridging effect between the upper and lower layers of concrete, enhancing the interfacial bonding force.

[0060] This technical solution has significant advantages. First, the addition of basalt fiber significantly improves the bonding strength between the upper and lower layers of concrete, ensuring the integrity and stability of the structure. Second, basalt fiber itself has excellent durability and corrosion resistance, which can significantly extend the service life of permeable concrete. Finally, this solution is easy to operate, does not increase the construction difficulty, and is easy to promote and apply in actual projects.

[0061] Therefore, this application solves the problem of low interfacial strength between layers of gradient materials by spreading part of basalt fiber before pouring the upper layer, and significantly improves the overall performance and durability of permeable concrete.

[0062] Furthermore, this application also proposes that the gradient pore control technology includes directional vibration. For the lower layer, an internal vibrator with a high frequency of 50 Hz is used for vibration to avoid the floating of the slurry; for the upper layer, a screed vibrator with a frequency of 30 Hz is used for vibration to quickly level the surface and avoid damaging the lower-layer structure. Using high-frequency vibration for the lower layer is beneficial to compaction, and using low-frequency vibration for the upper layer is beneficial to maintaining large pores.

[0063] The application of directional vibration technology in the construction of permeable concrete solves the deficiency of traditional vibration methods in pore gradient control. Through different vibration frequencies, it ensures the density and strength of the lower-layer concrete, while maintaining a larger porosity in the upper layer to improve water permeability. Specifically, an internal vibrator with a high frequency of 50 Hz is used for the lower-layer vibration, which can effectively avoid the floating of the slurry and ensure the density and strength of the lower-layer concrete. A screed vibrator with a frequency of 30 Hz is used for the upper-layer vibration, which can quickly level the upper-layer concrete and avoid damaging the lower-layer structure, maintaining a larger porosity in the upper layer.

[0064] Furthermore, the application of the directional vibration technology can not only solve the deficiencies of traditional vibration methods in pore gradient control, but also improve the construction quality and performance of permeable concrete. High-frequency vibration in the lower layer is beneficial to the density and strength of the concrete, while low-frequency vibration in the upper layer is beneficial to maintaining a larger porosity, thus improving the water permeability. Therefore, the application of the directional vibration technology in the construction of permeable concrete not only ensures the strength of the concrete, but also improves the water permeability, solving the deficiencies of traditional construction methods in pore gradient control.

[0065] Furthermore, this application also proposes that the porosity of the upper layer is 25% to 35%, and the porosity of the lower layer is 10% to 15%.

[0066] This solution realizes the gradient control of permeable concrete by adjusting the porosity of the upper and lower layers. Specifically, the upper layer has a larger porosity and can quickly permeate water, while the lower layer has a smaller porosity, a relatively slower water permeation speed, but higher strength. The purpose of this design is to provide sufficient structural strength while ensuring the water permeability performance.

[0067] In specific implementation, the aggregate particle size of the upper layer is larger, forming larger pores for the rapid passage of water; the aggregate particle size of the lower layer is relatively smaller, and the pores are also smaller. Although the water permeation speed slows down, it can provide higher strength. In addition, different vibration frequencies are used to further optimize the pore structure. High-frequency vibrators are used in the lower layer to increase the density, and low-frequency vibrators are used in the upper layer to maintain larger pores.

[0068] This design solution effectively solves the contradiction between the water permeability and mechanical properties of traditional permeable concrete. Through reasonable pore rate gradient control, the balance between water permeability and strength is achieved, the construction process is optimized, and the overall performance is improved.

[0069] Furthermore, this application also proposes that the compressive strength of the upper layer is 15 to 20 MPa, and the compressive strength of the lower layer is 20 to 30 MPa.

[0070] The compressive strengths of the upper and lower layers are 15 to 20 MPa and 20 to 30 MPa respectively. This design is mainly to meet the mechanical property requirements of permeable concrete at different levels. The aggregate particle size of the upper layer is larger, the pore size is large, and the water permeability is good, but the relative strength is low; the aggregate particle size of the lower layer is smaller, the pore size is small, the water permeability is slightly poor, but the strength is high. Through this gradient design, the water permeability and mechanical properties can be effectively balanced, enabling permeable concrete to ensure good water permeability effect and bear a certain load in practical applications.

[0071] Specifically, the upper layer has a compressive strength of 15 to 20 MPa, which can ensure that the upper layer has sufficient strength to resist external light loads, while the large porosity ensures good water permeability. The lower layer has a compressive strength of 20 to 30 MPa, providing higher strength to support the entire structure, while the small porosity ensures the stability and durability of the structure. Thus, through a reasonable design of the compressive strength gradient, the optimal performance of permeable concrete in different application scenarios can be achieved.

[0072] Compared with the prior art, the design of the compressive strength gradient of the permeable concrete in this application can better meet the dual requirements of water permeability and mechanical properties, solve the problem that it is difficult to balance the strength and water permeability of traditional permeable concrete, and improve the practicability and reliability of permeable concrete.

[0073] This application solves the problem that it is difficult to meet the performance requirements of permeable concrete by only relying on two parameters, namely the water-binder ratio and porosity, for mix design in the prior art by using granite coarse aggregate, cement, basalt fiber, silica fume, fly ash, water reducer and water as core materials. Specifically, the granite coarse aggregate provides high strength and durability, the cement serves as the main binder to ensure the stability and bonding of the structure, the basalt fiber enhances the tensile strength and toughness of the concrete, the silica fume and fly ash as admixtures improve the compactness and durability of the concrete, and the water reducer improves the workability and fluidity of the concrete.

[0074] The selection of granite coarse aggregate can significantly improve the overall strength and durability of permeable concrete. The incorporation of basalt fiber further enhances the tensile strength and toughness of the concrete and reduces the generation of cracks. The silica fume and fly ash as admixtures can fill the voids between the aggregates, improve the compactness of the concrete, and enhance its durability. The use of water reducer improves the workability of the concrete, making it easier to pour and vibrate during construction.

[0075] Furthermore, this application also proposes that the core materials include granite coarse aggregate, cement, basalt fiber, silica fume, fly ash, water reducer and water.

[0076] In the technical solution provided by this application, the selection and proportioning of the core materials further optimize the performance of permeable concrete. Specifically, the combined use of granite coarse aggregate, cement, basalt fiber, silica fume, fly ash, water reducer and water not only improves the mechanical properties of permeable concrete, but also enhances its water permeability.

[0077] The granite coarse aggregate in the core material features high strength and durability, capable of providing the skeletal structure required for permeable concrete. Cement, as the main binder, acts together with other materials to form a solid porous structure. The addition of basalt fibers can effectively improve the crack resistance and toughness of permeable concrete. Silica fume and fly ash, as mineral admixtures, can not only improve the microstructure of concrete but also enhance its impermeability and durability. The use of water reducers helps to reduce the water-cement ratio, improving the strength and density of concrete.

[0078] The combined use of these core materials, through optimizing the mixture ratio and construction technology, solves the problems of traditional permeable concrete in terms of performance and construction difficulty. For example, the addition of basalt fibers can form a network structure inside the concrete, improving its crack resistance and toughness. The use of silica fume and fly ash can fill the tiny pores in the concrete, enhancing its impermeability. Water reducers can, while maintaining the workability, reduce the water-cement ratio, thus improving the strength and density of concrete.

[0079] This application significantly improves the mechanical properties and water permeability of permeable concrete by optimizing the mixture ratio of its core materials. Compared with the prior art, this technical solution not only solves the problems of traditional permeable concrete in terms of performance and construction difficulty but also provides a more efficient and durable method for preparing permeable concrete. Therefore, this technical solution has significant technical advantages in practical applications.

[0080] The above are only the preferred embodiments of this invention patent and are not intended to limit this invention patent. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of this invention patent shall be included within the protection scope of this invention patent.

Claims

1. A process for controlling the pore gradient of permeable concrete, which mainly comprises the following steps: Step 1: Preliminary material preparation and testing, including grading, screening and pretreatment of aggregates; Step 2: Pore gradient layered design, the porosity increases from the bottom layer to the surface layer, that is, the upper layer has large aggregate particle size, large pore size, fast water permeability, and the lower layer has relatively small particles, small pore size, relatively slow water permeability, and higher strength; Step 3: Preparation of test pieces: first, fill the mixer with slurry of the same mix ratio, then add coarse aggregate and cementitious material and stir for 2 minutes. After stirring evenly, add water reducer and 50% and continue stirring for 1 minute. Then add the remaining water and stir for 1 minute. Finally, add fiber and stir for 2 minutes. Step 4: Layered pouring process, including layer-by-layer placement and vibration compaction; Step 5: Vacuum adsorption assistance, after pouring, excess slurry is sucked out by negative pressure to accurately control pore connectivity; Step 6: Interface treatment between layers, including roughening and interface agent spraying; Step 7: Gradient pore control technology; Step 8: Maintenance and surface treatment, including moisturizing maintenance and silane impregnation; Step 9: Porosity and performance testing, the compressive strength loading rate is 0.5~0.8MPa / s, and the permeability coefficient test method refers to the coarse aggregate soil constant head test method.

2. A process for controlling pore gradient of permeable concrete according to claim 1, characterized in that: The roughening includes treating the surface with a wire brush or sandblasting to form roughness before the final setting of the lower layer or within 1 hour after pouring.

3. A process for controlling pore gradient of permeable concrete according to claim 2, characterized in that: The roughness Ra is ≥ 0.5 mm.

4. A process for controlling pore gradient of permeable concrete according to claim 2, characterized in that: The interface agent is cement paste, and the cement paste is sprayed.

5. A process for controlling pore gradient of permeable concrete according to any one of claims 3 or 4, characterized in that: Sprinkling some basalt fiber before pouring the upper layer will help connect the upper and lower layers.

6. A process for controlling pore gradient of permeable concrete according to claim 1, characterized in that: The gradient pore control technology includes directional vibration, which includes lower layer vibration and upper layer vibration. The lower layer vibration uses an inserted high-frequency vibrator to prevent the slurry from floating up. After the upper layer material is added, the vibration uses a low-frequency flat plate vibrator. The lower layer is vibrated at a high frequency, which is conducive to compaction, and the upper layer is vibrated at a low frequency, which is conducive to maintaining large pores.

7. A process for controlling pore gradient of permeable concrete according to claim 6, characterized in that: The porosity of the upper layer is 25% to 35%, and the porosity of the lower layer is 10% to 15%.

8. A process for controlling pore gradient of permeable concrete according to claim 7, characterized in that: The compressive strength of the upper layer is 15 to 20 MPa, and the compressive strength of the lower layer is 20 to 30 MPa.

9. The process for controlling pore gradient of permeable concrete according to claim 1, characterized in that: The core material includes granite coarse aggregate, cement, basalt fiber, silica fume, fly ash, water reducing agent and water.

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