Ecological water permeable brick and preparation method thereof

Abstract

The invention discloses an ecological water permeable brick and a preparation method thereof, and relates to the technical field of ecological building materials.The ecological water permeable brick comprises a wear-resistant layer, a transition layer and a water storage layer which are sequentially stacked, the wear-resistant layer is made of first activated aggregate, an alkali-activated cementing material and silicon carbide whiskers, and the particle size of the first activated aggregate is 5-8 nm; the materials of the transition layer comprise a second activated aggregate, an alkali-activated cementing material and basalt fibers, and the particle size of the second activated aggregate is 3-5 nm; the material of the water storage layer comprises a third activated aggregate, an alkali-activated cementing material and SiO2 / phase-change paraffin microcapsules, and the particle size of the third activated aggregate is 1-3 nm. The wear-resistant layer, the transition layer and the water storage layer which are sequentially stacked are adopted, and the wear-resistant layer, the transition layer and the water storage layer are prepared from the activated aggregates with different particle sizes and different materials, so that the compressive strength, the permeability coefficient and the freeze-thaw resistance of the ecological water permeable brick can be improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of ecological building materials, and particularly relates to an ecological water-permeable brick and a preparation method thereof. BACKGROUND

[0002] With the rapid advancement of urbanization in China, a huge amount of construction waste is generated annually, and the traditional landfill treatment method has brought serious environmental challenges. Although the use of recycled aggregate to prepare ecological water-permeable bricks provides an environmentally friendly outlet for the resource utilization of construction waste, it still faces significant technical bottlenecks: the strength of the product is insufficient due to the porosity and water absorption characteristics of the recycled aggregate, the water permeability and mechanical properties are difficult to optimize simultaneously, the durability is not good, and the energy consumption of the traditional production process is too high. These problems restrict the large-scale popularization and application of recycled aggregate water-permeable bricks, and it is urgent to achieve breakthroughs through technological innovation. SUMMARY

[0003] The main purpose of the present application is to provide an ecological water-permeable brick and a preparation method thereof, which aims to solve the problem that the existing ecological water-permeable bricks cannot simultaneously consider water permeability and mechanical properties.

[0004] To achieve the above-mentioned purpose, the present application provides an ecological water-permeable brick, which comprises a wear-resistant layer, a transition layer and a water storage layer stacked in sequence, wherein:

[0005] The material of the wear-resistant layer comprises first activated aggregate, alkali-activated cementitious material and silicon carbide whisker, and the particle size of the first activated aggregate is 5-8 nm;

[0006] The material of the transition layer comprises second activated aggregate, alkali-activated cementitious material and basalt fiber, and the particle size of the second activated aggregate is 3-5 nm;

[0007] The material of the water storage layer comprises third activated aggregate, alkali-activated cementitious material and SiO2 / phase change paraffin microcapsule, and the particle size of the third activated aggregate is 1-3 nm.

[0008] In an embodiment, the porosity of the wear-resistant layer is 18%-22%; and / or,

[0009] The porosity of the transition layer is 25%-28%; and / or,

[0010] The porosity of the water storage layer is 30%-35%; and / or,

[0011] The thickness of the wear-resistant layer is 35-45 mm; and / or,

[0012] The thickness of the transition layer is 45-55 mm; and / or,

[0013] The thickness of the water storage layer is 50-70 mm; and / or,

[0014] The mass percentage of needle-shaped particles in the first activated aggregate is less than 8%; and / or,

[0015] The powder content of the first activated aggregate is less than or equal to 0.5%; and / or,

[0016] The angularity coefficient of the second activated aggregate is 1.4-1.6; and / or,

[0017] The powder content of the second activated aggregate is less than or equal to 1.2%; and / or,

[0018] The surface roughness of the third activated aggregate is 3.5-4.2 μm; and / or,

[0019] The crushing index of the third activated aggregate is less than or equal to 10%.

[0020] In an embodiment, the material of the wear-resistant layer comprises 55-65 parts of the first activated aggregate, 30-38 parts of the alkali-activated cementitious material, 1.0-2.0 parts of silicon carbide whiskers, and 0.3-0.8 parts of water reducing agent; and / or,

[0021] The material of the wear-resistant layer further comprises water, and the mass ratio of water to the alkali-activated cementitious material is (0.25-0.3):1; and / or,

[0022] The material of the transition layer comprises, in mass percentage, 65-75 parts of the second activated aggregate, 22-28 parts of the alkali-activated cementitious material, 0.5-1.2 parts of basalt fiber, and 0.1-0.4 parts of thickening agent; and / or,

[0023] The material of the transition layer further comprises water, and the mass ratio of water to the alkali-activated cementitious material is (0.3-0.35):1; and / or,

[0024] The material of the water storage layer comprises, in mass percentage, 50-60 parts of the third activated aggregate, 25-35 parts of the alkali-activated cementitious material, 8-12 parts of SiO2 / phase change paraffin microcapsules, and 2-4 parts of resin; and / or,

[0025] The material of the water storage layer further comprises water, and the mass ratio of water to the alkali-activated cementitious material is (0.32-0.38):1; and / or,

[0026] The SiO2 / phase change paraffin microcapsules comprise phase change paraffin and a SiO2 shell layer coated on the phase change paraffin.

[0027] The present application also provides a preparation method of the ecological water-permeable brick.

[0028] S10. Remove impurities from the waste concrete, crush it in multiple stages, and screen it to obtain the first recycled aggregate, the second recycled aggregate, and the third recycled aggregate, respectively.

[0029] S20. The first recycled aggregate, the second recycled aggregate, and the third recycled aggregate are activated and dried respectively to obtain the first activated aggregate, the second activated aggregate, and the third activated aggregate.

[0030] S30. Mix the first activated aggregate, alkali-activated cementitious material, silicon carbide whiskers, water-reducing agent and water to obtain wear-resistant layer mixture;

[0031] S40. Mix the second activated aggregate, alkali-activated cementitious material, basalt fiber, thickener and water to obtain the transition layer mixture.

[0032] S50. Mix the third activated aggregate, alkali-activated cementitious material, SiO2 / phase change paraffin microcapsules, resin and water to obtain a water storage layer mixture.

[0033] S60. The wear-resistant layer mixture, transition layer mixture and water storage layer mixture are respectively molded, combined and cured to obtain ecological permeable bricks.

[0034] In one embodiment, step S10 includes the following steps:

[0035] The waste concrete is cleaned by a combination of magnetic separation, air separation, and manual sorting.

[0036] The cleaned concrete is subjected to extrusion crushing, impact crushing and ball milling in sequence to obtain crushed waste concrete.

[0037] The crushed waste concrete is subjected to multi-stage vibrating screening to obtain first recycled aggregate, second recycled aggregate and third recycled aggregate.

[0038] In one embodiment, in step S20, the activation treatment is performed by sequentially using a silane coupling agent solution, a vinyltris(2-methoxyethoxy)silane solution, and a tetraethyl orthosilicate-based SiO2 sol.

[0039] In one embodiment, in step S20, the activation treatment comprises: sequentially treating with a silane coupling agent solution at 40–50°C for 20–30 min, ultrasonically treating with a vinyltris(2-methoxyethoxy)silane solution at 30–40 kHz for 15–25 min, and activating with a tetraethyl orthosilicate-based SiO2 sol at a pH of 10.2–10.8 and a temperature of 60–70°C; and / or,

[0040] The silane coupling agent solution contains silane coupling agent of mass percentage C1, and the vinyltris(2-methoxyethoxy)silane solution contains vinyltris(2-methoxyethoxy)silane of mass percentage C2, wherein C1 is 0.5%–0.8%, C2 is 0.2%–0.4%, and the C1:C2 ratio is (2–3):1; and / or,

[0041] The ethyl silicate-based SiO2 sol comprises ethyl silicate, ethanol, and water, wherein the molar ratio of ethyl silicate, ethanol, and water is 1:(4-6):(5-7).

[0042] In one embodiment, step S60 includes the following steps:

[0043] S601. Pour the wear-resistant layer mixture into mold one, vibrate, roll, and microwave cure for 1.5h to 2h to obtain the initial setting wear-resistant layer. Lay basalt fiber woven mesh on the surface of the initial setting wear-resistant layer, vibrate, and CO2 cure for 5 to 8 days to obtain the wear-resistant layer with pre-embedded fiber mesh.

[0044] S602. Pour the transition layer mixture onto the wear-resistant layer surface of the pre-embedded fiber mesh, vibrate, roll, and cure in a steam environment of 60-65℃ for 8-10 hours to obtain the initial setting transition layer. Prepare the first tooth-shaped structure on the surface of the initial setting transition layer.

[0045] S603. Pour the water storage layer mixture into mold two, vibrate, roll and press, and cure at 20-25℃ for 8-10 hours to obtain the initial setting water storage layer. The mold two has a second tooth structure that meshes with the first tooth structure on the surface of the initial setting wear-resistant layer.

[0046] S604. Engage the second toothed structure of the initial setting period water storage layer with the first toothed structure of the initial setting period transition layer, pressurize, and cure to obtain an ecological permeable brick for the initial setting period.

[0047] S605. The permeable ecological bricks in the initial setting stage are cured to obtain permeable ecological bricks.

[0048] In one embodiment, step S605 includes:

[0049] The transition layer in the initial setting stage permeable ecological brick is cured for 5-8 days at 23-27℃ and RH greater than 95%.

[0050] The water storage layer in the initial setting stage permeable ecological brick is cured in a water immersion environment of 18-22℃ for 5-8 days.

[0051] In one embodiment, in step S601, the pressure during vibration of the wear-resistant layer is 11-13 MPa; and / or,

[0052] In step S602, the pressure during vibration of the transition layer is 7–9 MPa; and / or,

[0053] In step S603, the pressure during vibration of the water storage layer is 5-6 MPa.

[0054] In the technical solution provided by this invention, the use of 5-8 nm first activated aggregate in the wear-resistant layer can improve the interfacial strength and wear resistance of the wear-resistant layer; the use of 3-5 nm first activated aggregate in the transition layer can improve the permeability and stress transfer of the ecological permeable brick; and the use of 1-3 nm first activated aggregate in the water storage layer can increase the porosity of the ecological permeable brick and enhance capillary action, thereby obtaining an ecological permeable brick that combines compressive strength and permeability. Furthermore, the use of silicon carbide whiskers in the wear-resistant layer can further synergistically improve the fracture resistance and wear resistance of the wear-resistant layer; the use of basalt fiber in the transition layer can improve the fracture resistance and freeze-thaw resistance of the transition layer; and the use of SiO2 / phase change paraffin microcapsules in the water storage layer can reduce the risk of freeze-thaw damage to the water storage layer, thereby improving the freeze-thaw resistance and fracture resistance of the ecological permeable brick. Detailed Implementation

[0055] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially. Furthermore, the meaning of "and / or" throughout the text includes three parallel solutions; for example, "A and / or B" includes solution A, or solution B, or a solution where both A and B are satisfied simultaneously. In addition, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0056] With the rapid advancement of urbanization in my country, the annual output of construction waste is enormous, and traditional landfill disposal methods have brought severe environmental challenges. While using recycled aggregates to prepare permeable bricks offers an environmentally friendly solution for the resource utilization of construction waste, it still faces significant technical bottlenecks: the inherent porosity and water absorption characteristics of recycled aggregates result in insufficient strength in the finished products, making it difficult to optimize permeability and mechanical properties in a coordinated manner, leading to poor durability; furthermore, traditional production processes consume excessive energy. These problems restrict the large-scale promotion and application of permeable bricks made from recycled aggregates, necessitating breakthroughs through technological innovation.

[0057] In view of this, the present invention proposes an eco-friendly permeable brick that can simultaneously improve permeability and mechanical properties.

[0058] The ecological permeable brick provided by this invention includes a wear-resistant layer, a transition layer, and a water storage layer stacked sequentially. The wear-resistant layer is made of a first activated aggregate, an alkali-activated cementitious material, and silicon carbide whiskers, wherein the particle size of the first activated aggregate is 5-8 nm. The transition layer is made of a second activated aggregate, an alkali-activated cementitious material, and basalt fiber, wherein the particle size of the second activated aggregate is 3-5 nm. The water storage layer is made of a third activated aggregate, an alkali-activated cementitious material, and SiO2 / phase change paraffin microcapsules, wherein the particle size of the third activated aggregate is 1-3 nm.

[0059] In the technical solution provided by this invention, the use of 5-8 nm first activated aggregate in the wear-resistant layer can improve the interfacial strength and wear resistance of the wear-resistant layer; the use of 3-5 nm first activated aggregate in the transition layer can improve the permeability and stress transfer of the ecological permeable brick; and the use of 1-3 nm first activated aggregate in the water storage layer can increase the porosity of the ecological permeable brick and enhance capillary action, thereby obtaining an ecological permeable brick that combines compressive strength and permeability. Furthermore, the use of silicon carbide whiskers in the wear-resistant layer can further synergistically improve the fracture resistance and wear resistance of the wear-resistant layer; the use of basalt fiber in the transition layer can improve the fracture resistance and freeze-thaw resistance of the transition layer; and the use of SiO2 / phase change paraffin microcapsules in the water storage layer can reduce the risk of freeze-thaw damage to the water storage layer, thereby improving the freeze-thaw resistance and fracture resistance of the ecological permeable brick.

[0060] In the wear-resistant layer, the silicon carbide whiskers can, on the one hand, cross both sides of the microcracks, bear tensile stress, change the crack propagation path, and consume fracture energy, thereby improving the mechanical properties of the wear-resistant layer. On the other hand, silicon carbide has a high Mohs hardness, which can form a wear-resistant skeleton in the wear-resistant layer and fill micropores, making the surface denser, thereby improving the wear resistance of the wear-resistant layer.

[0061] In the transition layer, basalt fibers can cross both sides of the microcracks, bear tensile stress, and improve the flexural strength of the transition layer. They can also hinder crack propagation when fine cracks appear. Due to the friction between the fiber and the matrix and the deformation of the fiber itself, the cracks are buffered, increasing the fracture energy of the transition layer and thus improving its mechanical properties. On the other hand, basalt fibers have good alkali resistance, and the basalt fibers, gel materials, and aggregates can form a microporous structure at the fiber-matrix interface in the transition layer to buffer frost heave stress and improve freeze-thaw resistance, thereby improving the durability of the transition layer.

[0062] Furthermore, the basalt fiber has an aspect ratio of 750-850, which provides good strength enhancement. The water-reducing agent can be, for example, a polycarboxylate superplasticizer. The thickener can be, for example, hydroxypropyl methylcellulose. The resin can be, for example, sodium polyacrylate.

[0063] In some embodiments, the SiO2 / phase change paraffin microcapsules comprise phase change paraffin and nano-silica coated with the phase change paraffin. Phase change paraffin can undergo a solid-liquid phase transition within a certain temperature range, absorbing or releasing latent heat. After being embedded in the brick, it can absorb heat at higher temperatures, lowering the brick's temperature; and release heat at lower temperatures, reducing the risk of freeze-thaw damage to the water reservoir. The SiO2 shell can participate in the hydration reaction during the brick forming process, improving interfacial bonding strength; and it can also reduce the risk of paraffin leakage, improving the durability of the SiO2 / phase change paraffin microcapsules.

[0064] In some embodiments, the porosity of the wear-resistant layer is 18%–22%; the porosity of the transition layer is 25%–28%; and the porosity of the water-retaining layer is 30%–35%. The lower porosity of the wear-resistant layer improves its strength and wear resistance. The higher porosity of the water-retaining layer increases its water storage capacity, enhances capillary action, and extends the water release time. The wear-resistant layer forms a rapid drainage main channel, the transition layer guides water flow through capillary action, and the water-retaining layer achieves slow-release permeation and humidity regulation functions. It should be noted that the porosity can be tested using methods such as mercury intrusion porosimetry, CT scanning, and vacuum saturation. The wear-resistant layer can be tested using mercury intrusion porosimetry to measure 5-50 μm functional pores, i.e., the main permeable channels; the transition layer can be tested using CT scanning to quantify the pore connectivity between the fiber and aggregate; and the water-retaining layer can be tested using a combination of vacuum saturation and mercury intrusion porosimetry to distinguish between water-retaining pores (>1 mm) and capillary pores (0.1-1 mm).

[0065] In some embodiments, the thickness of the wear-resistant layer is 35-45 mm; the thickness of the transition layer is 45-55 mm; and the thickness of the water storage layer is 50-70 mm.

[0066] In some implementations, the mass percentage of needle-shaped and flaky particles in the first activated aggregate is less than 8%. If the mass percentage of needle-shaped and flaky particles is too high, it can weaken the aggregate interlocking effect, reduce flexural strength, and may even form directional permeable channels, causing excessively high local flow velocity in the permeable brick and leading to erosion. Therefore, a mass percentage of needle-shaped and flaky particles of less than 8% can reduce stress concentration, improve compressive strength, and prevent needle-shaped particles from clogging pores and causing fluctuations in the permeability coefficient. It is understood that the mass percentage of needle-shaped and flaky particles can be reduced by selectively choosing the crushing method and / or by ball milling after crushing.

[0067] In some implementations, the powder content of the first activated aggregate is less than or equal to 0.5%. If the powder content is too high, on the one hand, the powder will hinder the penetration of the cementitious material, leading to a decrease in bond strength; on the other hand, the fine powder may migrate upon contact with water and clog pores, resulting in a decrease in the permeability coefficient. Therefore, a powder content of less than 0.5% can reduce the coating of powder on the gel material, improve the bonding strength, and also improve the stability of the permeability coefficient. It is understood that the powder can be removed by air classification to reduce the powder content.

[0068] In some embodiments, the angularity factor of the second activated aggregate is 1.4 to 1.6; the powder content of the second activated aggregate is less than or equal to 1.2%. If the angularity factor is too low, the particles are too round, resulting in high material bulk density but easy rolling, thereby reducing structural stability and low shear strength. If the angularity factor is too high, the particles are too angular, which may lead to excessive pore tortuosity, reducing water permeability, and may also cause stress concentration leading to microcracks. Therefore, an angularity factor of 1.4 to 1.6 can balance the sliding between particles and the interlocking ability of aggregates, improving the compressive strength and water permeability of the transition layer.

[0069] In some embodiments, the surface roughness of the third activated aggregate is 3.5–4.2 μm; the crushing index of the third activated aggregate is less than or equal to 10%. It should be noted that the crushing index represents the ability of coarse aggregate to resist crushing under gradually increasing loads, and can be characterized by measuring the percentage of fine particles produced by the aggregate sample under a specified pressure. The surface roughness of the third activated aggregate can improve interfacial bonding strength and increase the surface adhesion of the third activated aggregate.

[0070] In some embodiments, the material of the wear-resistant layer includes 55 to 65 parts of first activated aggregate, 30 to 38 parts of alkali-activated cementitious material, 1.0 to 2.0 parts of silicon carbide whiskers, and 0.3 to 0.8 parts of water-reducing agent; the material of the wear-resistant layer also includes water, wherein the mass ratio of water to alkali-activated cementitious material is (0.25 to 0.3):1.

[0071] In some embodiments, the transition layer material, by mass percentage, comprises 65 to 75 parts of second activated aggregate, 22 to 28 parts of alkali-activated cementitious material, 0.5 to 1.2 parts of basalt fiber, and 0.1 to 0.4 parts of thickener; the transition layer material also comprises water, wherein the mass ratio of water to alkali-activated cementitious material is (0.3 to 0.35):1.

[0072] In some embodiments, the material of the water storage layer, by mass percentage, includes 50 to 60 parts of third activated aggregate, 25 to 35 parts of alkali-activated gelling material, 8 to 12 parts of SiO2 / phase change paraffin microcapsules, and 2 to 4 parts of resin; the material of the water storage layer also includes water, wherein the mass ratio of water to alkali-activated gelling material is (0.32 to 0.38):1.

[0073] This invention also proposes a method for preparing the ecological permeable brick as described above, the method comprising the following steps:

[0074] S10. Remove impurities from the waste concrete, crush it in multiple stages, and screen it to obtain the first recycled aggregate, the second recycled aggregate, and the third recycled aggregate, respectively.

[0075] S20. The first recycled aggregate, the second recycled aggregate, and the third recycled aggregate are activated and dried respectively to obtain the first activated aggregate, the second activated aggregate, and the third activated aggregate.

[0076] S30. Mix the first activated aggregate, alkali-activated cementitious material, silicon carbide whiskers, water-reducing agent and water to obtain wear-resistant layer mixture;

[0077] S40. Mix the second activated aggregate, alkali-activated cementitious material, basalt fiber, thickener and water to obtain the transition layer mixture.

[0078] S50. Mix the third activated aggregate, alkali-activated cementitious material, SiO2 / phase change paraffin microcapsules, resin and water to obtain a water storage layer mixture.

[0079] S60. The wear-resistant layer mixture, transition layer mixture and water storage layer mixture are respectively molded, combined and cured to obtain ecological permeable bricks.

[0080] Before step S30, a polyvinyl alcohol solution with a mass ratio of 0.5% to 0.7% can be sprayed onto the surface of the first activated aggregate to enhance the interfacial wettability of the first activated aggregate and promote the spreading of the cementitious slurry; form a PVA film with a thickness of 50 to 100 nm to inhibit water absorption by the aggregate; and chelate the hydroxyl groups in PVA with the metal ions in the cementitious material to enhance the interfacial bonding energy.

[0081] In step S30, silicon carbide whiskers are first dry-mixed with 30%–40% alkali-activated cementitious material at a speed of 40–45 r / min for 3–5 min. This utilizes the cementitious material as a dispersion medium, breaking the van der Waals forces of the whiskers through dry-mixing shear force, thus achieving pre-dispersion. Simultaneously, the cementitious material particles adsorb onto the whisker surface, forming a physical isolation layer. The remaining alkali-activated cementitious material is then added and mixed to obtain a premix. Gradually increasing the amount of cementitious material reduces the local whisker concentration and prevents secondary agglomeration. The first activated aggregate, with its surface sprayed with polyvinyl alcohol solution, the premix, water, and water-reducing agent are then mixed sequentially at a speed of 25–35 r / min for 1–1.5 min, followed by a mixing speed of 60–70 r / min for 2–4 min to obtain the wear-resistant layer mixture.

[0082] The alkali-activated gel material includes slag and steel slag.

[0083] Before step S40, a 0.5% polyvinyl alcohol solution can be sprayed onto the surface of the second activated aggregate to enhance the interfacial wettability of the second activated aggregate.

[0084] Before step S40, the basalt fiber can be pretreated by immersing it in a 0.3% to 0.35% silane coupling agent solution for 10 to 15 minutes and drying it at 60 to 65°C until the moisture content is less than 1%, thus obtaining the treated basalt fiber.

[0085] In step S40, the thickener can be premixed with the treated basalt fibers to improve the uniformity of fiber dispersion. The thickener can, for example, be hydroxypropyl methylcellulose (HPMC).

[0086] In step S40, the first activated aggregate with polyvinyl alcohol solution sprayed on the surface can be dry-mixed with 50% to 55% alkali-activated cementitious material for 2 to 4 minutes, then thickener can be added and mixed with the treated basalt fiber mixture for 3 to 4 minutes, and then the remaining alkali-activated cementitious material can be added and mixed with water to obtain the transition layer mixture.

[0087] Before step S50, a 0.5% polyvinyl alcohol solution can be sprayed onto the surface of the third activated aggregate to enhance the interfacial wettability of the third activated aggregate.

[0088] Before step S50, the surface of the SiO2 / phase change paraffin microcapsules can be modified with epoxy resin to form a dense layer on the surface, thus obtaining the treated SiO2 / phase change paraffin microcapsules.

[0089] In step S50, the third activated aggregate can be premixed with 60% to 70% of alkali-activated cementitious material for 2 to 4 minutes, then water-absorbing resin can be added and mixed for 3 to 4 minutes, then the remaining alkali-activated cementitious material, the treated SiO2 / phase change paraffin microcapsules and water can be added and mixed at a speed of 40 to 50 r / min for 3 to 4 minutes to obtain the water storage layer mixture.

[0090] In some implementations, step S10 includes the following steps:

[0091] The waste concrete is cleaned by a combination of magnetic separation, air separation, and manual sorting.

[0092] The cleaned concrete is subjected to extrusion crushing, impact crushing and ball milling in sequence to obtain crushed waste concrete.

[0093] The crushed waste concrete is subjected to multi-stage vibrating screening to obtain first recycled aggregate, second recycled aggregate and third recycled aggregate.

[0094] It should be noted that the magnetic separation can be performed on waste concrete using a magnetic separator to remove metallic impurities; the air separation can remove lightweight impurities such as wood chips and plastics; and manual sorting can remove large impurities larger than 300mm.

[0095] The crushing process can be performed using a dual-chamber jaw crusher (e.g., model PEW-400×600) to coarsely crush the demolished concrete blocks (≤800mm) into intermediate products of 30-50mm. The crushing tooth plate angle is 24°-28° to reduce the generation of needle-like and flaky particles; the moving jaw speed is controlled at 220-240r / min to match production capacity requirements and ensure continuous processing; the discharge port size is dynamically adjusted to 80-100mm via a hydraulic system; a permanent magnet separator with a magnetic field strength ≥1200 Gauss is used to remove metal impurities such as reinforcing bars; and dust suppression spraying is performed simultaneously, with water mist particles of 20-50μm in diameter.

[0096] The impact crushing can be carried out using a vertical shaft impact crusher to crush 30-50mm materials to 10-20mm and improve particle shape. Specifically, it can be carried out using a vortex chamber vertical crusher with an impeller speed of 1800-2200 r / min to give the aggregates greater impact kinetic energy. The first impact zone is equipped with wear-resistant alloy liners with an incident angle of 55°-60°, combined with an aggregate-aggregate dual collision mode to prioritize the crushing of old mortar with lower strength. The second grinding zone maintains an aggregate collision velocity difference of ≥15m / s. The matching air classification system has an air velocity of 8-12m / s.

[0097] Ball milling can process materials from 10-20mm to 1-8mm, eliminating microcracks and creating fresh fracture surfaces through grinding media collision, thus improving the adhesion of subsequent modifiers. Specifically, 30mm diameter steel balls and 15mm diameter zirconia balls can be used for ball milling, with a volume ratio of (3-4):(6-7) to balance impact force and grinding efficiency. The cylinder rotation speed can be 75% of the critical speed, specifically 26-30 r / min. Atomized spraying can maintain a material moisture content of 2.5%-3.5%, preventing dust explosions and promoting microcrack healing. During ball milling, the relationship between grinding time and initial aggregate particle size can be: T = 0.8D. 1.5 (10≤D≤20). Where T is the grinding time (in min) and D is the median initial particle size of the aggregate (in mm). By adjusting the grinding time using the above formula, the output can be controlled to have a continuous gradation of 1-8 mm.

[0098] In some implementations, a three-layer probability screen (amplitude 4-6 mm, frequency 800-1000 r / min) can be used for multi-stage vibrating screening. The screen hole diameter of the upper screen is 8 mm, the screen hole diameter of the middle screen is 5 mm, and the screen hole diameter of the lower screen is 3 mm, to obtain the first recycled aggregate, the second recycled aggregate, and the third recycled aggregate.

[0099] In some embodiments, in step S20, the activation treatment involves sequentially using a silane coupling agent solution, a vinyltris(2-methoxyethoxy)silane solution, and a tetraethyl orthosilicate-based SiO2 sol. SiO2 forms Si-O-Si chemical bonds with the silane coupling agent, improving interfacial bonding strength; however, its alkali resistance is poor. Therefore, a vinyltris(2-methoxyethoxy)silane (VTMOEO) solution is further used, where the vinyl groups are more stable in an alkaline environment and can form a steric hindrance protective layer. Finally, the tetraethyl orthosilicate-based SiO2 sol is used, where the hydroxyl groups (-OH) on the SiO2 surface form Si-O-Si bonds with the silane coupling agent, further improving interfacial bonding strength. After gelation, the sol forms a continuous network structure, thereby reducing porosity.

[0100] In some embodiments, in step S20, the activation treatment is as follows: sequentially treating with a silane coupling agent solution at 40-50°C for 20-30 min, ultrasonically treating with a vinyltris(2-methoxyethoxy)silane solution at 30-40 kHz for 15-25 min, and activating with a ethyl silicate-based SiO2 sol at a pH of 10.2-10.8 and a temperature of 60-70°C; the mass percentage of the silane coupling agent in the silane coupling agent solution is C1, and the mass percentage of the vinyltris(2-methoxyethoxy)silane in the vinyltris(2-methoxyethoxy)silane solution is C2, wherein C1 is 0.5%-0.8%, C2 is 0.2%-0.4%, and the C1:C2 ratio is (2-3):1; the ethyl silicate-based SiO2 sol comprises ethyl silicate, ethanol, and water, wherein the molar ratio of ethyl silicate, ethanol, and water is 1:(4-6):(5-7). Ultrasonic treatment can generate local high temperature and high pressure, which promotes the grafting reaction of silane on the surface of aggregates. On the other hand, it can remove surface impurities and expose fresh active sites.

[0101] When processing recycled aggregates of different particle sizes, the same processing parameters or different processing parameters can be used. In some embodiments of the present invention, different parameters can be used to process different recycled aggregates to make them more suitable for the corresponding layers.

[0102] For example, when impregnating the first recycled aggregate, it can be impregnated at 50°C for 30 min with a 0.8% KH550 ethanol solution (ethanol to water mass ratio of 6:4), ultrasonically treated with a 0.4% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 4.5 by acetic acid) for 15 min, and then vacuum impregnated with a TEOS solution (TEOS, ethanol and water mass ratio of 1:4:5, pH adjusted to 10.5 by ammonia) for 20 min.

[0103] For example, when impregnating the second recycled aggregate, it can be impregnated at 45°C for 25 min with a 0.6% KH550 ethanol solution (ethanol to water mass ratio of 5:5), ultrasonically treated with a 0.3% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 5 with acetic acid) for 20 min, and then vacuum impregnated with a TEOS solution (TEOS, ethanol and water mass ratio of 1:5:6, pH adjusted to 10 with ammonia) for 25 min.

[0104] For example, when impregnating the third-generation recycled aggregate, it can be impregnated at 40°C for 20 min with a 0.5% KH550 ethanol solution (ethanol to water mass ratio of 4:6), followed by ultrasonic treatment with a 0.2% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 5.5 with acetic acid) for 25 min, and then vacuum impregnated with a TEOS solution (TEOS, ethanol, and water mass ratio of 1:6:7, pH adjusted to 9.5 with ammonia) for 30 min. Using a low-concentration treatment solution for small-diameter particles can reduce the consumption of KH550.

[0105] In some implementations, step S60 includes the following steps:

[0106] S601. Pour the wear-resistant layer mixture into mold one, vibrate, roll, and microwave cure for 1.5h to 2h to obtain the initial setting wear-resistant layer. Lay basalt fiber woven mesh on the surface of the initial setting wear-resistant layer, vibrate, and CO2 cure for 5 to 8 days to obtain the wear-resistant layer with pre-embedded fiber mesh.

[0107] S602. Pour the transition layer mixture onto the wear-resistant layer surface of the pre-embedded fiber mesh, vibrate, roll, and cure in a steam environment of 60-65℃ for 8-10 hours to obtain the initial setting transition layer. Prepare the first tooth-shaped structure on the surface of the initial setting transition layer.

[0108] S603. Pour the water storage layer mixture into mold two, vibrate, roll and press, and cure at 20-25℃ for 8-10 hours to obtain the initial setting water storage layer. The mold two has a second tooth structure that meshes with the first tooth structure on the surface of the initial setting wear-resistant layer.

[0109] S604. Engage the second toothed structure of the initial setting period water storage layer with the first toothed structure of the initial setting period transition layer, pressurize, and cure to obtain an ecological permeable brick for the initial setting period.

[0110] S605. The permeable ecological bricks in the initial setting stage are cured to obtain permeable ecological bricks.

[0111] In the technical solution of the present invention, the cementitious materials of each layer permeate each other through hydration products (CSH gel) before the initial setting period to form chemical bonds; vibration pressure causes the aggregate to embed into adjacent layers, forming a toothed interlocking structure to achieve mechanical interlocking and improve the interlayer bonding force; there is a basalt woven mesh between the wear-resistant layer and the transition layer, which spans the interlayer interface and physically anchors and enhances the shear resistance.

[0112] In the technical solution of this invention, different curing methods are adopted for different structural layers. Among them, microwave curing of the wear-resistant layer can selectively heat the interface area and promote the rapid nucleation of CSH gel. CO2 infiltration curing can cause the calcium hydroxide in the material to react to form calcium carbonate, increasing strength and reducing porosity. The transition layer is cured in a steam environment, which can maintain the humidity RH≥95%, prevent plastic shrinkage cracking, and stabilize the porosity of the transition layer at 25-28%. The water storage layer is cured at room temperature of 20-25℃ to avoid leakage of phase change material due to temperature rise.

[0113] It is understandable that a release agent can be sprayed onto mold one before the wear-resistant layer mixture is poured into mold one to facilitate demolding; and a release agent can be sprayed onto mold two before the water storage layer mixture is poured into mold two to facilitate demolding.

[0114] In step S601, the process of pouring the wear-resistant layer mixture into mold one, vibrating, rolling, and curing for 1.5h to 2h to obtain the initial setting wear-resistant layer may include: after pouring the wear-resistant layer mixture into mold one, vibrating it first at a frequency of 30Hz and a pressure of 5MPa for 0 to 10s to initially degas and reduce porosity; then vibrating it at a frequency of 50Hz and a pressure of 12MPa for 10 to 25s to increase the bulk density and further reduce porosity; then rolling it at a pressure of 12MPa for 25 to 30s to eliminate elastic rebound. Subsequently, a double roller press can be used for secondary rolling, with a roller diameter of 300mm, a linear speed of 0.2m / s, and a linear pressure of 120N / mm, rolling once in each direction to increase surface hardness and reduce the permeability coefficient; microwave curing for 1.5h to 2h yields the initial setting wear-resistant layer.

[0115] Before step S601, the basalt fiber web can be modified to improve interfacial bonding strength. Optionally, the basalt fiber web can be impregnated with an aqueous solution of a silane coupling agent. The silane coupling agent in the aqueous solution has a mass percentage of 0.3%–0.35%, and the pH is adjusted to 4.3–4.7 by adding acetic acid. Silane hydrolyzes to generate Si-OH, which bonds with hydroxyl groups on the fiber surface, enhancing the fiber-matrix interfacial bonding energy. The impregnated fibers need to be dried; optionally, they can be dried at a constant temperature of 58–62℃ for 50–60 min to achieve a basalt fiber moisture content ≤1%.

[0116] In step S601, the step of “laying a basalt fiber woven mesh on the surface of the wear-resistant layer during the initial setting period, vibrating it, and obtaining a wear-resistant layer with a pre-embedded fiber mesh” may include: laying a basalt fiber woven mesh on the surface of the initially set wear-resistant layer, vibrating it at a frequency of 20Hz and a pressure of 12MPa for 5s, so that it is embedded in the wear-resistant layer and at a distance of 2.5 to 3.5mm from the surface of the wear-resistant layer.

[0117] It is understandable that the transition layer mixture is also formed in mold one. In step S602, the step of "pouring the transition layer mixture onto the wear-resistant layer surface of the pre-embedded fiber mesh, vibrating, rolling, and curing for 1.5h-2h to obtain the initial setting transition layer" may include: pouring the transition layer mixture onto the wear-resistant layer surface of the pre-embedded fiber mesh, vibrating at a frequency of 45Hz and a pressure of 8MPa for 20s to interweave the transition layer aggregate with the basalt fiber mesh. Subsequently, a double-roller press can be used for rolling, once in each direction, and curing for 1.5h-2h to obtain the initial setting transition layer. In the step of "preparing the first toothed structure on the surface of the initial setting transition layer," a toothed template can be used to press the transition layer surface to prepare the first toothed structure.

[0118] Before step S603, soluble salt rods are uniformly inserted into mold two, with a spacing of 100-120 mm and a diameter of 2-3 mm. After pouring in the water storage layer mixture, vibrating, and rolling, the pore-forming agent (soluble salt rods) is dissolved by washing with water to form interconnected pores in the water storage layer.

[0119] In step S603, the step of "pouring the water storage layer mixture into mold two, vibrating, rolling, and curing for 1.5h to 2h to obtain the initial setting water storage layer" may include: pouring the water storage layer mixture into mold two, vibrating at a frequency of 35Hz and a pressure of 5MPa for 15s, rolling with a double roller press, rolling once in each direction, and curing for 1.5h to 2h to obtain the initial setting transition layer with a second tooth-shaped structure.

[0120] In some embodiments, the pressure during vibration of the wear-resistant layer in step S601 is 11–13 MPa; the pressure during vibration of the transition layer in step S602 is 7–9 MPa; and the pressure during vibration of the water storage layer in step S603 is 5–6 MPa. Through gradient pressure molding, the wear-resistant layer can seal harmful macropores, preventing siltation; and the water storage layer can retain functional pores, thereby constructing a multi-scale permeable network.

[0121] Before step S604, an interface agent may be applied to the surfaces of the second toothed structure of the initial setting period water storage layer and the first toothed structure of the initial setting period transition layer to improve interlayer bonding. The interface agent may, for example, be a 3% (w / w) polyvinyl alcohol solution.

[0122] In step S604, the engagement of the first tooth structure and the second tooth structure can enhance the bonding force between the transition layer and the water storage layer.

[0123] In some embodiments, step S605 includes:

[0124] Step S605 includes:

[0125] The transition layer in the initial setting stage permeable ecological brick is cured for 5-8 days at 20-30℃ and RH greater than 95%.

[0126] The water storage layer in the initial setting stage permeable ecological brick is cured in a water immersion environment of 18-22℃ for 5-8 days.

[0127] In the technical solution of the present invention, the transition layer is cured in an environment of 20-30°C and RH greater than 95% to promote the secondary hydration reaction of steel slag or other substances in the alkali-activated material; the water storage layer is cured in a water immersion environment of 18-22°C to allow the water-absorbing resin therein to absorb water and swell.

[0128] It should be noted that when the above-mentioned curing conditions are carried out simultaneously, a zoned temperature-controlled mold can be used for curing. The mold can have an internal electromagnetic shielding layer and a heat-conducting partition to achieve independent heating of each layer. When the above-mentioned curing is carried out on the water storage layer and the transition layer, the wear-resistant layer can be cured at room temperature.

[0129] This invention breaks through the bottleneck of the contradiction between the "strength, permeability and durability" of traditional recycled aggregate permeable bricks by using a technical system of material modification, structural design and process coupling.

[0130] By designing different aggregate particle sizes and porosities in each layer, the wear-resistant layer forms a fast drainage main channel, the transition layer guides water flow through capillary action, and the water storage layer achieves slow-release infiltration and humidity regulation functions.

[0131] By modifying the aggregate, the interfacial tension is reduced, the capillary penetration efficiency is improved, the blockage of fine powder is reduced, and the pore connectivity is maintained.

[0132] Gradient pressure molding enables the wear-resistant layer to seal harmful large pores and prevent siltation; it also enables the water storage layer to retain functional pores, thereby constructing a multi-scale permeable network.

[0133] The addition of SiO2 / phase change paraffin microcapsules can regulate pore opening and closing at different temperatures, improving temperature-adaptive permeability. The addition of absorbent resin can balance the permeability requirements of rainy and dry seasons, improving dynamic permeability efficiency.

[0134] In summary, the ecological permeable bricks provided by this invention can simultaneously achieve good permeability, good strength, and good freeze-thaw resistance.

[0135] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0136] Example 1

[0137] An eco-friendly permeable brick is provided, comprising a wear-resistant layer, a transition layer, and a water storage layer stacked sequentially, wherein:

[0138] The wear-resistant layer comprises 60 parts of first activated aggregate, 35 parts of alkali-activated cementitious material, 1.5 parts of silicon carbide whiskers, 0.5 parts of polycarboxylate superplasticizer, and 10 parts of water; the particle size of the first activated aggregate is 5-8 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0139] The transition layer consists of 70 parts of second activated aggregate, 25 parts of alkali-activated cementitious material, 0.8 parts of basalt fiber, 0.2 parts of thickener (hydroxypropyl methylcellulose), and 8 parts of water; the particle size of the second activated aggregate is 3-5 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2;

[0140] The material of the water storage layer includes 55 parts of third activated aggregate, 30 parts of alkali-activated cementitious material, 10 parts of SiO2 / phase change paraffin microcapsules, 3 parts of water-absorbing resin (sodium polyacrylate), and 10.5 parts of water; the particle size of the third activated aggregate is 1-3 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0141] The preparation method of the permeable ecological brick is as follows:

[0142] S10. The waste concrete is then subjected to magnetic separation, air separation, and manual sorting in sequence to remove impurities. The impurity-removed concrete is then subjected to extrusion crushing (moving jaw stroke 38mm, rotation speed 230r / min, output particle size 30-50mm), impact crushing (impeller rotation speed 2000r / min, incident angle 55°, wind speed 10m / s air separation for dust removal), and ball milling (steel balls and zirconia balls are mixed and ground at a mass ratio of 3:7, moisture content 3.0%) to obtain crushed waste concrete. The crushed waste concrete is then subjected to multi-stage vibrating screening using a three-layer probability screen (amplitude 6mm, frequency 1000r / min). The screen aperture diameter of the upper screen is 8mm, the screen aperture diameter of the middle screen is 5mm, and the screen aperture diameter of the lower screen is 3mm to obtain the first recycled aggregate, the second recycled aggregate, and the third recycled aggregate.

[0143] S20. The first recycled aggregate was impregnated in 0.8% KH550 ethanol solution (ethanol to water mass ratio of 6:4) at 50℃ for 30 min, ultrasonically treated in 0.4% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 4.5 by acetic acid) for 15 min, and then vacuum impregnated in TEOS solution (TEOS, ethanol and water mass ratio of 1:4:5, pH adjusted to 10.5 by ammonia) for 20 min, and vacuum dried for 2 h.

[0144] The second recycled aggregate was impregnated with 0.6% KH550 ethanol solution (ethanol to water mass ratio of 5:5) at 45℃ for 25 min, ultrasonically treated with 0.3% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 5 with acetic acid) for 20 min, and then vacuum impregnated with TEOS solution (TEOS, ethanol and water mass ratio of 1:5:6, pH adjusted to 10 with ammonia) for 25 min, and vacuum dried for 2 h.

[0145] The third recycled aggregate was impregnated with 0.5% KH550 ethanol solution (ethanol to water mass ratio of 4:6) at 40℃ for 20 min, ultrasonically treated with 0.2% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 5.5 by acetic acid) for 25 min, and then vacuum impregnated with TEOS solution (TEOS, ethanol and water mass ratio of 1:6:7, pH adjusted to 9.5 by ammonia) for 30 min, and vacuum dried for 2 h.

[0146] The first activated aggregate, the second activated aggregate, and the third activated aggregate were obtained respectively.

[0147] S30. Mix the first activated aggregate, alkali-activated cementitious material, silicon carbide whiskers, water-reducing agent and water to obtain wear-resistant layer mixture;

[0148] S40. Mix the second activated aggregate, alkali-activated cementitious material, basalt fiber, thickener and water to obtain the transition layer mixture.

[0149] S50. Mix the third activated aggregate, alkali-activated cementitious material, SiO2 / phase change paraffin microcapsules, resin and water to obtain a water storage layer mixture.

[0150] S601. Pour the wear-resistant layer mixture into mold one, first vibrate it at a frequency of 30Hz and a pressure of 5MPa for 0-10s; then vibrate it at a frequency of 50Hz and a pressure of 12MPa for 10-25s; then roll it at a frequency of 0Hz and a pressure of 12MPa for 25-30s. Then, use a double roller press for secondary rolling, with a roller diameter of 300mm, a linear speed of 0.2m / s, and a linear pressure of 120N / mm, rolling once in each direction. Microwave cure for 1.5h-2h to obtain the initial setting wear-resistant layer. Modify the basalt fiber woven mesh with 0.3% silane coupling agent, lay the modified basalt fiber woven mesh on the surface of the initial setting wear-resistant layer, and vibrate it at 12MPa for 5s to obtain the wear-resistant layer with embedded fiber mesh.

[0151] S602. Pour the transition layer mixture onto the wear-resistant layer surface of the pre-embedded fiber mesh, vibrate at 8MPa, roll press, cure in a steam environment at 65℃ for 10 hours, and then cure with CO2 for 8 days to obtain the initial setting transition layer. Prepare the first tooth-shaped structure on the surface of the initial setting transition layer.

[0152] S603. Pour the water storage layer mixture into mold two, vibrate at 5MPa, roll and press, and cure at 25℃ for 10h to obtain the initial setting water storage layer. The mold two has a second tooth structure that meshes with the first tooth structure on the surface of the initial setting wear-resistant layer.

[0153] S604. Engage the second toothed structure of the initial setting period water storage layer with the first toothed structure of the initial setting period transition layer, and cure to obtain an ecological permeable brick for the initial setting period.

[0154] S605. The transition layer in the initial setting stage ecological permeable brick is cured for 8 days at 25°C and RH greater than 95%; the water storage layer in the initial setting stage ecological permeable brick is cured for 8 days in a water immersion environment at 20°C to obtain the ecological permeable brick.

[0155] Example 2

[0156] An eco-friendly permeable brick is provided, comprising a wear-resistant layer, a transition layer, and a water storage layer stacked sequentially, wherein:

[0157] The wear-resistant layer comprises 55 parts of first activated aggregate, 30 parts of alkali-activated cementitious material, 1.0 part of silicon carbide whiskers, 0.3 parts of polycarboxylate superplasticizer, and 8.4 parts of water; the particle size of the first activated aggregate is 5-8 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0158] The transition layer consists of 65 parts of second activated aggregate, 22 parts of alkali-activated cementitious material, 0.5 parts of basalt fiber, 0.1 parts of thickener (hydroxypropyl methylcellulose), and 7 parts of water; the particle size of the second activated aggregate is 3-5 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0159] The material of the water storage layer includes 50 parts of third activated aggregate, 25 parts of alkali-activated cementitious material, 8 parts of SiO2 / phase change paraffin microcapsules, 2 parts of water-absorbing resin (sodium polyacrylate), and 7.5 parts of water; the particle size of the third activated aggregate is 1-3 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0160] The preparation method of the permeable ecological bricks is the same as in Example 1.

[0161] Example 3

[0162] An eco-friendly permeable brick is provided, comprising a wear-resistant layer, a transition layer, and a water storage layer stacked sequentially, wherein:

[0163] The wear-resistant layer comprises 65 parts of first activated aggregate, 38 parts of alkali-activated cementitious material, 2.0 parts of silicon carbide whiskers, 0.8 parts of polycarboxylate superplasticizer, and 10.6 parts of water; the particle size of the first activated aggregate is 5-8 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0164] The transition layer consists of 75 parts of second activated aggregate, 28 parts of alkali-activated cementitious material, 1.2 parts of basalt fiber, 0.4 parts of thickener (hydroxypropyl methylcellulose), and 9 parts of water; the particle size of the second activated aggregate is 3-5 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0165] The material of the water storage layer includes 60 parts of third activated aggregate, 35 parts of alkali-activated cementitious material, 12 parts of SiO2 / phase change paraffin microcapsules, 4 parts of water-absorbing resin (sodium polyacrylate), and 10.5 parts of water; the particle size of the third activated aggregate is 1-3 nm; the mass ratio of slag to steel slag in the alkali-activated cementitious material is 8:2.

[0166] The preparation method of the permeable ecological bricks is the same as in Example 1.

[0167] Example 4

[0168] An ecological permeable brick is provided, except that in step S601, no roller pressing is performed, that is, no secondary roller pressing is performed on the vibrated wear-resistant layer mixture. All other steps and parameters are the same as in Example 1.

[0169] Example 5

[0170] An ecological permeable brick is provided, and all steps and parameters are the same as in Example 1, except for step S605. Step S605 includes:

[0171] The permeable ecological bricks in the initial setting stage were cured at 25℃ for 8 days to obtain permeable ecological bricks.

[0172] Comparative Example 1

[0173] An ecological permeable brick is provided. The material of the ecological permeable brick includes 55 parts of activated aggregate, 30 parts of alkali-activated cementitious material, 10 parts of SiO2 / phase change paraffin microcapsules, 3 parts of resin, and 10.5 parts of water, wherein the particle size of the activated aggregate is 1-8 nm.

[0174] The preparation method of the permeable ecological brick is as follows:

[0175] S10. The waste concrete is then subjected to magnetic separation, air separation, and manual sorting in sequence to remove impurities. The impurity-removed concrete is then subjected to extrusion crushing (moving jaw stroke 38mm, rotation speed 230r / min, output particle size 30-50mm), impact crushing (impeller rotation speed 2000r / min, incident angle 55°, air velocity 10m / s air separation for dust removal), and ball milling (steel balls and zirconia balls are mixed and ground at a mass ratio of 3:7, moisture content 3.0%) to obtain crushed waste concrete. The crushed waste concrete is then sieved using a sieve with a screen diameter of 8mm to obtain recycled aggregate with a particle size of 1-8nm.

[0176] S20. The recycled aggregate was impregnated with 0.5% KH550 ethanol solution (ethanol to water mass ratio of 4:6) at 40℃ for 20 min, ultrasonically treated with 0.2% vinyltris(2-methoxyethoxy)silane solution (pH adjusted to 5.5 by acetic acid) for 25 min, and then vacuum impregnated with TEOS solution (TEOS, ethanol and water mass ratio of 1:6:7, pH adjusted to 9.5 by ammonia) for 30 min, and vacuum dried for 2 h to obtain activated aggregate.

[0177] S30. Mix activated aggregate, alkali-activated cementitious material, SiO2 / phase change paraffin microcapsules, resin and water to obtain a mixture.

[0178] S40. Pour the mixture into the mold, vibrate at 5MPa, roll and press, and cure at 25℃ for 10 hours to obtain the initial setting permeable brick. Cure the initial setting permeable brick in water soaking at 20℃ for 8 days to obtain the ecological permeable brick.

[0179] Comparative Example 2

[0180] An ecological permeable brick is provided, wherein the ecological permeable brick is identical to that in Example 1 except that it does not contain silicon carbide whiskers, basalt fibers and SiO2 / phase change paraffin microcapsules.

[0181] Comparative Example 3

[0182] An ecological permeable brick is provided, wherein the particle size of the first activated aggregate, the second activated aggregate and the third activated aggregate are all 1-8 nm, and the steps and parameters are the same as in Example 1, except that step S10 is different.

[0183] S10 involves sequentially removing impurities from waste concrete using magnetic separation, air separation, and manual sorting; then sequentially subjecting the removed concrete to extrusion crushing (jaw stroke 38mm, rotation speed 230r / min, output particle size 30-50mm), impact crushing (impeller rotation speed 2000r / min, incident angle 55°, air velocity 10m / s for air separation and dust removal), and ball milling (mixing and grinding steel balls and zirconia balls at a mass ratio of 3:7, with a moisture content of 3.0%) to obtain crushed waste concrete; finally, screening the crushed waste concrete using a sieve with an 8mm aperture to obtain first recycled aggregate, second recycled aggregate, and third recycled aggregate, wherein the particle size of the first recycled aggregate, second recycled aggregate, and third recycled aggregate are all 1-8nm.

[0184] Comparative Example 4

[0185] An ecological permeable brick is provided, except that step S20 is not used, that is, the first recycled aggregate, the second recycled aggregate and the third recycled aggregate are not activated, and the other steps and parameters are the same as those in Example 1.

[0186] Comparative Example 5

[0187] An ecological permeable brick is provided, wherein the ecological permeable brick is identical to that in Example 1 except that the SiO2 / phase change paraffin microcapsules are replaced with phase change paraffin.

[0188] Other parameters of Examples 1-5 and Comparative Examples 1-5 are shown in Table 1.

[0189] Table 1. Parameters of Examples 1-5 and Comparative Examples 1-5

[0190]

[0191] Performance testing

[0192] (1) The compressive strength, flexural strength, permeability coefficient, freeze-thaw life and interlayer bonding strength of the ecological permeable bricks prepared in Examples 1 to 5 and Comparative Examples 1 to 5 were tested according to the following test standards and recorded in Table 2 below.

[0193] Compressive strength: GB / T 50081-2019

[0194] Flexural strength: GB / T 50081-2019

[0195] Permeability coefficient: CJJ / T 188-2012

[0196] Freeze-thaw life: GB / T 2542-2012

[0197] Interlayer bond strength: JGJ / T 70-2009

[0198] Table 2. Gamete survival rate and 3-month biomass growth rate of the permeable ecological bricks prepared in Examples 1-5 and Comparative Examples 1-5.

[0199]

[0200] As can be seen from Table 2, compared with Comparative Examples 1-4, the ecological permeable bricks provided in Examples 1-5 have better compressive strength, flexural strength, permeability coefficient, freeze-thaw life and interlayer bonding strength; compared with Comparative Example 5 which uses phase change paraffin, the ecological permeable bricks obtained by using SiO2 / phase change paraffin microcapsules in Examples 1-5 have better freeze-thaw life.

[0201] Furthermore, in the embodiments, the permeable ecological bricks obtained by using the same curing conditions for each layer in Embodiment 5 at room temperature have lower compressive strength, flexural strength, permeability coefficient, freeze-thaw life, and interlayer bonding strength than the permeable ecological bricks obtained by using different curing conditions in Embodiments 1 to 4.

[0202] The above description is merely a preferred embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention under the inventive concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. An ecological permeable brick, characterized in that, The permeable ecological brick comprises a wear-resistant layer, a transition layer, and a water storage layer stacked sequentially, wherein: The wear-resistant layer is made of a first activated aggregate, an alkali-activated cementitious material, and silicon carbide whiskers, wherein the particle size of the first activated aggregate is 5-8 nm. The transition layer is made of a second activated aggregate, an alkali-activated cementitious material, and basalt fiber, wherein the particle size of the second activated aggregate is 3-5 nm. The material of the water storage layer includes a third activated aggregate, an alkali-activated gelling material, and SiO2 / phase change paraffin microcapsules, wherein the particle size of the third activated aggregate is 1-3 nm.

2. The permeable ecological brick as described in claim 1, characterized in that, The porosity of the wear-resistant layer is 18%–22%; and / or, The porosity of the transition layer is 25%–28%; and / or, The porosity of the water storage layer is 30%–35%; and / or, The thickness of the wear-resistant layer is 35–45 mm; and / or, The thickness of the transition layer is 45–55 mm; and / or, The thickness of the water storage layer is 50–70 mm; and / or, The mass percentage of needle-shaped and flaky particles in the first activated aggregate is less than 8%; and / or, The first activated aggregate has a powder content of less than or equal to 0.5%; and / or, The angularity coefficient of the second activated aggregate is 1.4–1.6; and / or, The second activated aggregate has a powder content of less than or equal to 1.2%; and / or, The surface roughness of the third activated aggregate is 3.5–4.2 μm; and / or, The crushing index of the third activated aggregate is less than or equal to 10%.

3. The permeable ecological brick as described in claim 1, characterized in that, By weight, the wear-resistant layer comprises 55-65 parts of first activated aggregate, 30-38 parts of alkali-activated cementitious material, 1.0-2.0 parts of silicon carbide whiskers, and 0.3-0.8 parts of water-reducing agent; and / or, The wear-resistant layer also includes water, wherein the mass ratio of water to alkali-activated cementitious material is (0.25–0.3):1; and / or, By weight percentage, the transition layer comprises 65-75 parts of second activated aggregate, 22-28 parts of alkali-activated cementitious material, 0.5-1.2 parts of basalt fiber, and 0.1-0.4 parts of thickener; and / or, The transition layer material further includes water, wherein the mass ratio of water to alkali-activated cementitious material is (0.3–0.35):1; and / or, By weight percentage, the material of the water reservoir comprises 50-60 parts of third activated aggregate, 25-35 parts of alkali-activated cementitious material, 8-12 parts of SiO2 / phase change paraffin microcapsules, and 2-4 parts of resin; and / or, The material of the water storage layer also includes water, wherein the mass ratio of water to alkali-activated cementitious material is (0.32–0.38):1; and / or, The SiO2 / phase change paraffin microcapsules comprise phase change paraffin and a SiO2 shell coating the phase change paraffin.

4. A method for preparing an ecological permeable brick as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S10. Remove impurities from the waste concrete, crush it in multiple stages, and screen it to obtain the first recycled aggregate, the second recycled aggregate, and the third recycled aggregate, respectively. S20. The first recycled aggregate, the second recycled aggregate, and the third recycled aggregate are activated and dried respectively to obtain the first activated aggregate, the second activated aggregate, and the third activated aggregate. S30. Mix the first activated aggregate, alkali-activated cementitious material, silicon carbide whiskers, water-reducing agent and water to obtain wear-resistant layer mixture; S40. Mix the second activated aggregate, alkali-activated cementitious material, basalt fiber, thickener and water to obtain the transition layer mixture. S50. Mix the third activated aggregate, alkali-activated cementitious material, SiO2 / phase change paraffin microcapsules, resin and water to obtain a water storage layer mixture. S60. The wear-resistant layer mixture, transition layer mixture and water storage layer mixture are respectively molded, combined and cured to obtain ecological permeable bricks.

5. The method for preparing permeable ecological bricks as described in claim 4, characterized in that, Step S10 includes the following steps: The waste concrete is cleaned by a combination of magnetic separation, air separation, and manual sorting. The cleaned concrete is subjected to extrusion crushing, impact crushing and ball milling in sequence to obtain crushed waste concrete. The crushed waste concrete is subjected to multi-stage vibrating screening to obtain first recycled aggregate, second recycled aggregate and third recycled aggregate.

6. The method for preparing permeable ecological bricks as described in claim 4, characterized in that, In step S20, the activation treatment is performed by sequentially using a silane coupling agent solution, a vinyltris(2-methoxyethoxy)silane solution, and a tetraethyl orthosilicate-based SiO2 sol.

7. The method for preparing permeable ecological bricks as described in claim 5 or 6, characterized in that, In step S20, the activation treatment is as follows: sequentially treating with a silane coupling agent solution at 40–50°C for 20–30 min, ultrasonically treating with a vinyltris(2-methoxyethoxy)silane solution at 30–40 kHz for 15–25 min, and activating with ethyl silicate-based SiO2 sol at a pH of 10.2–10.8 and a temperature of 60–70°C; and / or, The silane coupling agent solution contains silane coupling agent of mass percentage C1, and the vinyltris(2-methoxyethoxy)silane solution contains vinyltris(2-methoxyethoxy)silane of mass percentage C2, wherein C1 is 0.5%–0.8%, C2 is 0.2%–0.4%, and the C1:C2 ratio is (2–3):1; and / or, The ethyl silicate-based SiO2 sol comprises ethyl silicate, ethanol, and water, wherein the molar ratio of ethyl silicate, ethanol, and water is 1:(4-6):(5-7).

8. The method for preparing permeable ecological bricks as described in claim 4, characterized in that, Step S60 includes the following steps: S601. Pour the wear-resistant layer mixture into mold one, vibrate, roll, and microwave cure for 1.5h to 2h to obtain the initial setting wear-resistant layer. Lay basalt fiber woven mesh on the surface of the initial setting wear-resistant layer, vibrate, and CO2 cure for 5 to 8 days to obtain the wear-resistant layer with pre-embedded fiber mesh. S602. Pour the transition layer mixture onto the wear-resistant layer surface of the pre-embedded fiber mesh, vibrate, roll, and cure in a steam environment of 60-65℃ for 8-10 hours to obtain the initial setting transition layer. Prepare the first tooth-shaped structure on the surface of the initial setting transition layer. S603. Pour the water storage layer mixture into mold two, vibrate, roll and press, and cure at 20-25℃ for 8-10 hours to obtain the initial setting water storage layer. The mold two has a second tooth structure that meshes with the first tooth structure on the surface of the initial setting wear-resistant layer. S604. Engage the second toothed structure of the initial setting period water storage layer with the first toothed structure of the initial setting period transition layer, pressurize, and cure to obtain an ecological permeable brick for the initial setting period. S605. The permeable ecological bricks in the initial setting stage are cured to obtain permeable ecological bricks.

9. The method for preparing permeable ecological bricks as described in claim 8, characterized in that, Step S605 includes: The transition layer in the initial setting stage permeable ecological brick is cured for 5-8 days at 23-27℃ and RH greater than 95%. The water storage layer in the initial setting stage permeable ecological brick is cured in a water immersion environment of 18-22℃ for 5-8 days.

10. The method for preparing permeable ecological bricks as described in claim 8, characterized in that, In step S601, the pressure during vibration of the wear-resistant layer is 11–13 MPa; and / or, In step S602, the pressure during vibration of the transition layer is 7–9 MPa; and / or, In step S603, the pressure during vibration of the water storage layer is 5-6 MPa.

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