Plant porous concrete brick based on plant leaching solution loaded biochar and preparation method thereof

Abstract

The application discloses a kind of based on plant leaching liquid load biochar's phytogenic porous concrete brick and preparation method thereof, it is related to phytogenic concrete technical field.The brick includes porous concrete matrix and fills in the pore of ecological base material in it;Ecological base material includes load plant leaching liquid's biochar particle, planting soil and water retaining agent.20%-40% of load plant leaching liquid's biochar accounts for the total mass of ecological base material, and plant leaching liquid load is 20%-40% of the mass of biochar.Its preparation method includes plant leaching liquid preparation, load biochar preparation, concrete brick body preparation, ecological base material preparation and filling paving.The application utilizes biochar adsorption and slow-release effect, realizes long-acting supply of nutrient, reduces leaching, improves vegetation survival rate, while maintaining good engineering performance of concrete, applicable to river slope protection, highway side slope, sponge city construction and other fields.

Description

Technical Field

[0001] This invention belongs to the field of planted concrete technology, specifically relating to a planted porous concrete brick based on biochar loaded with plant leachate and its preparation method, which is used to improve the nutrient slow release effect of planted bricks, reduce nutrient leaching rate, and significantly improve vegetation survival rate and ecological function. Background Technology

[0002] While traditional concrete slope protection offers good engineering stability and durability, it suffers from weak ecological function, easily creating a "hardened" landscape that hinders plant growth. Existing vegetated concrete technologies primarily promote plant growth by covering the surface with soil or directly adding fertilizer, but these methods suffer from problems such as rapid nutrient release, severe leaching, low vegetation survival rates, limited ecological substrate performance, and poor environmental adaptability.

[0003] Biochar, as a porous adsorbent material, can be used to retain water and fertilizer, but its own nutrients are limited, and its direct application has a slow promoting effect; plant extracts are rich in fast-acting nutrients, but they are easily washed away by rainwater, and their fertilizer effect is short-lived.

[0004] Therefore, there is an urgent need to develop a plant-based porous concrete brick that loads plant extracts onto biochar and fills the porous concrete brick to form an internally and externally interconnected ecological matrix layer, in order to achieve long-term slow release of nutrients, reduce leaching rate, and improve vegetation survival rate and ecological adaptability. Summary of the Invention

[0005] The purpose of this invention is to provide a plant-based porous concrete brick supported on biochar using plant leachate and its preparation method, so as to achieve the following technical effects: Long-lasting slow-release nutrients: By loading nutrient-rich plant extracts onto porous biochar, the adsorption and slow-release functions of biochar are utilized to achieve a continuous and stable supply of nutrients to plants.

[0006] Reduce nutrient leaching rate: Reduce nutrient loss caused by rainfall or irrigation and improve nutrient utilization efficiency.

[0007] Improve vegetation survival rate: Improve the water retention and air permeability of the substrate, while providing a habitat for microorganisms, thereby increasing vegetation survival rate and coverage.

[0008] Maintaining engineering performance: Achieving excellent ecological functions while ensuring the strength and permeability of porous concrete bricks.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: In a first aspect, a plant-based porous concrete brick loaded with biochar using plant extract is characterized by comprising a porous concrete brick body with built-in channels and an ecological substrate filling the channels.

[0010] The porous concrete bricks are prepared from the following raw materials: cement, coarse aggregate, fine aggregate, and water-reducing agent.

[0011] Further, the raw materials of the porous concrete brick are (by weight): 200-300 parts of cement, preferably 220-280 parts; 1400-1800 parts of coarse aggregate, preferably 1500-1700 parts; 0-200 parts of fine aggregate, preferably 0-150 parts; 2-5 parts of water-reducing agent, preferably 2.5-4 parts; and 60-110 parts of water, preferably 70-100 parts.

[0012] Further, the cement is PO 42.5 or PO 52.5 ordinary Portland cement; the coarse aggregate is crushed stone or gravel with a particle size of 5-30 mm, preferably 10-20 mm; the fine aggregate is medium sand or manufactured sand with a fineness modulus of 2.3-3.0; the water-reducing agent is polycarboxylate water-reducing agent or naphthalene-based water-reducing agent; the water is tap water or drinking water, and its dosage is preferably to meet a water-cement ratio of 0.28-0.35.

[0013] Furthermore, the thickness of the porous concrete brick is 50-120mm, preferably; it has vertical channels inside with a depth of 40-100mm, preferably 45-105mm; and the porosity is 15-35%, preferably 20-30%.

[0014] Furthermore, the porous concrete brick body has interlocking protrusions and interlocking grooves on its side for splicing and positioning adjacent bricks.

[0015] The ecological substrate filling the pores includes biochar loaded with plant extracts, planting soil, water-retaining agent, and microbial agent (optional).

[0016] Furthermore, the raw material ratio of the ecological substrate based on plant extract loaded biochar is as follows (by mass parts): 20-40 parts of biochar loaded with plant extract, preferably 30-35 parts; 50-70 parts of planting soil, preferably 55-65 parts; 5-15 parts of water-retaining agent, preferably 8-12 parts; and 0-2 parts of microbial agent, preferably 0.5-1.5 parts (added as needed, not essential).

[0017] Furthermore, the biochar loaded with plant extract comprises plant extract and biochar; the planting soil is selected from at least one of humus, garden soil, and peat soil, with an organic matter content ≥3% and a pH value of 6.0-7.5; the water-retaining agent is a polyacrylate superabsorbent polymer, starch graft copolymer, or a combination thereof; and the microbial agent is selected from Bacillus, nitrogen-fixing bacteria, phosphate-solubilizing bacteria, or a combination thereof.

[0018] Furthermore, the plant extract is an aqueous extract of leguminous plants, alfalfa, milkvetch, or a combination thereof, with a total nitrogen content of 5-20 g / L, preferably 10-15 g / L, a total phosphorus content of 1-5 g / L, preferably 2-4 g / L, and a total potassium content of 3-10 g / L, preferably 10-15 g / L.

[0019] Furthermore, the biochar has a particle size of 1-10 mm, preferably 2-5 mm; a specific surface area of ​​50-500 m² / g, preferably 200-400 m² / g; and a porosity of ≥30%, preferably ≥40%.

[0020] Furthermore, the plant extract loading is 20–40% of the biochar mass, preferably 25–35%.

[0021] Secondly, the method for preparing the plant-based porous concrete brick supported on biochar using plant leachate includes the following steps: S1. Preparation of plant extract, the steps are as follows: S1.1: Select tender stems and leaves of leguminous plants (soybeans, broad beans, peas, etc.) such as alfalfa or milkvetch. They should be fresh, free from pests and diseases, and free from mold. After washing to remove mud and impurities, drain them and chop them into 1-3cm pieces. S1.2: Add the tender stem and leaf fragments described in S1.1 to deionized water or distilled water at a material-to-liquid ratio of 1:(8-12) (mass ratio), stir well to form a mixture; S1.3 The mixture described in S1.2 is heated in a water bath or jacket at 80-100°C for 1-3 hours to form a mixture containing plant extract; S1.4 Filter the mixture in S1.3 through a 200-mesh filter or gauze to remove plant residues, and obtain a light green to yellowish-green plant extract. Cool it to room temperature for later use (the plant extract should be used as soon as possible. If it needs to be stored, it should be placed in a refrigerator at 4°C and the storage period should not exceed 7 days). S1.5 The pH of the plant extract is adjusted to 6.5-7.5 using sodium hydroxide solution and / or dilute hydrochloric acid; S2. Preparation of biochar loaded with plant extract, the steps are as follows: S2.1: Mix biochar with the plant extract prepared in S1 at a ratio of 1:(0.2-1) (by mass); S2.2 Stir the mixture described in S2.1 for 5-10 minutes. After stirring evenly, let it stand and soak for 12-48 hours under dark conditions. The soaking temperature is 15-25℃. S2.4 After the soaking process described in S2.2 is completed, excess liquid on the surface of the biochar is drained off using a 200-mesh filter to obtain biochar particles saturated with plant extract. S2.5 Spread the biochar described in S2.4 evenly on a stainless steel tray, with a thickness not exceeding 3cm, and dry it in an oven at 60-80℃ until the moisture content is ≤10%; Preferably, the drying temperature is 70℃, the drying time is 5-6 hours, and the clothes are turned over every hour to ensure even heating. S2.6 After drying, biochar loaded with plant extract is obtained. It is dark brown or dark brown in appearance, has a slight plant odor, and feels dry and loose. S3. Preparation of porous concrete bricks, the steps are as follows: S3.1: Weigh cement, coarse aggregate, fine aggregate (optional), and water-reducing agent according to the proportions described in claim 1 or 2, with a weighing accuracy of ±2%.

[0022] S3.2 Place the cement, coarse aggregate and optional fine aggregate weighed in S3.1 into a mixer and dry mix for 2 minutes to form a uniformly mixed dry material.

[0023] S3.4 Add the water-reducing agent and mixing water weighed in S3.1 to the dry material obtained in S3.2, and continue stirring for 2-4 minutes to form a uniform wet material.

[0024] S3.5 Pour the wet material into a steel or plastic mold that has been pre-coated with a release agent, and vibrate it for 30-60 seconds using a vibration table or a handheld vibrator, preferably 45 seconds.

[0025] S3.6 After curing for 24 hours at a temperature of 15-25℃ and a relative humidity of >80%, the product is demolded.

[0026] S3.7 Place the unfinished bricks obtained in S3.5 in a curing room at a temperature of 15-25℃ or cover them with a damp cloth or plastic film and spray water for curing; spray water 2-3 times a day for the first 7 days to keep the surface moist; spray water once a day from the 8th to the 28th day or adjust according to the weather conditions.

[0027] S4. Prepare the eco-friendly substrate, following these steps: S4.1 Weigh the biochar loaded with plant extract, planting soil, water-retaining agent, and optional microbial agent prepared in S2.4 according to the raw material ratio of the ecological substrate described in claim 1.

[0028] S4.2 Sift the planting soil weighed in S4.1 to remove impurities such as stones and tree roots.

[0029] S4.3 Mix the biochar loaded with plant extract weighed in S4.1 with the sieved planting soil in S4.2, and stir thoroughly for 5-10 minutes with a shovel or electric mixer to ensure that the biochar is evenly distributed in the planting soil.

[0030] S4.4 Add the water-retaining agent weighed in S4.1 evenly to the mixture obtained in S4.3, and continue stirring for 5-10 minutes.

[0031] S4.5 Optionally, if using a microbial agent, activate it with warm water at 30-40℃ for 2-4 hours, then add it evenly to the mixture obtained in S4.4 and stir until homogeneous.

[0032] S4.6 The prepared eco-friendly substrate should be used within 24 hours, or covered with a film for storage, with a storage period not exceeding 7 days.

[0033] S5. Filling with eco-friendly substrate, the steps are as follows: S5.1 Take porous concrete bricks prepared in S3.6 with a curing period of more than 28 days, ensuring that the surface is free of cracks and the strength meets the standard (compressive strength ≥15MPa).

[0034] S5.2 Use a blower or air compressor (0.5-0.8MPa) to clean the dust and debris in the bricks and filling grooves described in S5.1.

[0035] S5.3: Fill the surface filling groove with ecological substrate: S5.3.1 Use a shovel or small shovel to fill the surface filling groove of the porous concrete brick described in S5.1 layer by layer with the ecological substrate prepared in step S4.6.

[0036] S5.3.2 After each layer of filling (approximately 20mm thick), gently compact it once with your palm or a wooden board. After compaction, the dry density of the eco-substrate should reach 70%-80% of the maximum dry density in the standard Protodyakonov compaction test (i.e., relative compaction). Ensure that the eco-substrate is in full contact with the bottom and sidewalls of the filling groove, without obvious gaps or voids. The compaction force should not be too great to avoid damaging the loose structure of the eco-substrate.

[0037] S5.3.3 Repeat filling and compaction until the filling groove is completely filled.

[0038] Thirdly, the application of the plant-based porous concrete bricks supported on biochar using plant leachate is as follows: S6. Porous vegetation concrete brick paving, the steps are as follows: S6.1: On the prepared paving base (such as crushed stone cushion or plain concrete cushion), determine the paving slope and mark the position according to the slope protection or paving design requirements to ensure that the paving surface is flat and the slope is consistent. S6.2: Lay the planted porous concrete bricks filled with ecological substrate obtained in S5.5 one by one on the base layer, leaving a 5-10 mm gap between the bricks. When laying, use a rubber mallet or wooden mallet to gently tap the brick surface to make it firmly adhere to the base layer and the surface flat; S6.3: If the brick body is provided with interlocking protrusions and interlocking grooves, adjacent bricks should be accurately engaged to improve overall stability; S6.4: Fill the gaps between the bricks described in S6.2 with the ecological substrate prepared in S4.6, until the gaps are full and the surface is slightly lower than the brick surface by 2-3 mm, so that it is integrated with the substrate in the filling groove on the brick surface to form a continuous planting layer. Filling method: Use a broom to sweep the eco-friendly substrate into the gaps until the gaps are filled, with the surface slightly lower than the brick surface by 2-3mm.

[0039] S7. Planting plants, the steps are as follows: Plant seeds are sown on the surface of the ecological substrate with a continuous planting layer as described in S7.1 and S6.4 at a density of 30-50 g / m²; or plant seedlings are planted directly at a density of 4-9 plants per brick. S7.2: Cover the seeds or seedlings with a thin layer (about 5 mm) of the ecological substrate prepared in S4.6 and gently compact it.

[0040] S8. Watering and Maintenance: S8.1: Spray water evenly on the paved surface where planting has been completed in S7.2. The water spraying intensity is 1-2 mm / min, so that the ecological substrate is fully moistened but not waterlogged. S8.2: Spray water 2-3 times a day (morning, noon, and evening) for the first 3 days to keep the ecological substrate moist and promote the germination of grass seeds or the rooting of seedlings.

[0041] S8.3: Spray water 2-3 times a day for the first 3 days after planting; from the 4th to the 30th day, adjust the spraying frequency according to the weather to keep the substrate moist; after 30 days, the vegetation will basically form a lawn, and water appropriately according to the season and climate.

[0042] Compared with the prior art, the advantages and beneficial effects of this invention include: (1) Nutrient slow release cycle is significantly extended and supply is long-lasting and stable: By loading nutrient-rich plant extract into porous biochar, the strong adsorption of biochar is used to fix nutrients and release them slowly during plant growth. This effectively overcomes the problem of rapid nutrient loss caused by traditional fertilizers or direct addition of extract, and achieves long-term and stable nutrient supply to plants.

[0043] (2) High nutrient utilization efficiency and environmentally friendly: The adsorption and slow release of nutrients by biochar greatly reduces the nutrient leaching rate caused by rainfall or irrigation, improves nutrient utilization efficiency, and reduces the risk of eutrophication of water bodies caused by nutrient loss, resulting in significant environmental benefits.

[0044] (3) Significantly improved vegetation survival rate and growth performance: The biochar loaded with plant extract and the ecological substrate work together to provide continuous nutrients, improve the water retention and air permeability of the substrate, and provide a habitat for beneficial microorganisms, thereby significantly improving the vegetation survival rate, coverage and root development under adverse conditions such as drought and barrenness.

[0045] (4) Balancing engineering and ecological performance with controllable overall cost: This invention achieves excellent ecological functions while maintaining the good engineering performance (strength and permeability) of porous concrete bricks. The biochar raw materials used are widely available and inexpensive, and the plant extract can be made in-house. The overall technical route utilizes waste resources, which is in line with the concept of sustainable development, and the overall cost is competitive. Attached Figure Description

[0046] Figure 1 This is an overall schematic diagram of the planted porous concrete mold and brick of the present invention; Figure 2 This is a schematic diagram of the overall structure of the planted porous concrete brick of the present invention; Figure 3 This is a top view of the planted porous concrete brick of the present invention; Figure 4 This is a schematic cross-sectional view of the planted porous concrete brick of the present invention; Figure 5 This is a schematic diagram of the biomaterial substrate of the present invention; Figure 6 This is a schematic diagram of the microstructure of the biochar particles loaded with plant extract according to the present invention. Figure 7 This is a flowchart of the preparation process of the present invention; Figure 8 This is a schematic diagram of the structure of the planted porous concrete mold of the present invention; Figure 9 This is a schematic top view of the planted porous concrete mold of the present invention; Figure 10 This is a schematic cross-sectional view of the planted porous concrete mold of the present invention; Figure 11 This is a schematic diagram of the vegetation concrete paving of the present invention; In the diagram: 1-Mold; 11-Left baffle of the mold; 12-Rear baffle of the mold; 13-Right baffle of the mold; 14-Front baffle of the mold; 15-Water-permeable hole baffle of the mold; 16-Filling groove baffle of the mold; 2-Brick body; 21-Interlocking protrusion; 22-Filling groove; 23-Interlocking groove; 24-Water-permeable hole; 25-Connecting pore; 3-Plant; 4-Bio-based material; 41-Biochar particles loaded with plant extract; 411-Biochar skeleton; 412-Biochar pores; 413-Potassium; 414-Nitrogen; 415-Water; 416-Phosphorus; 42-Bio-inoculant; 43-Water-retaining agent; 44-Planting soil; 5-Pavement gap. Detailed Implementation

[0047] To make the objectives, technical solutions, and advantages of the present invention clearer, the present invention will be further described in detail below with reference to specific embodiments.

[0048] Example 1: Standard type of planted porous concrete brick Step 1: Preparation of plant extract 10 kg of fresh alfalfa stems and leaves were selected, washed to remove dirt and sand, drained, and chopped into 2 cm pieces. 100 kg of deionized water was added (solid-to-liquid ratio 1:10), and the mixture was heated in a water bath at 90℃ for 2 hours, stirring every 30 minutes. After extraction, the solution was filtered through a 200-mesh sieve to obtain approximately 90 kg of a pale green plant extract, which was then cooled to room temperature. The extract composition was determined to be: total nitrogen 12.5 g / L, total phosphorus 2.8 g / L, total potassium 6.2 g / L, and pH 7.3.

[0049] Step 2: Preparation of biochar loaded with plant extract 20 kg of rice husk charcoal (obtained by pyrolysis at 400℃, particle size 3-5 mm, specific surface area 280 m² / g, porosity 42%) was mixed with 60 kg of the plant extract prepared in step 1 (material-to-liquid ratio 1:3, mass ratio). The mixture was stirred thoroughly in a plastic bucket for 10 minutes, then allowed to stand and soak for 24 hours at 20℃. Stirring was performed every 6 hours for 10 minutes each time. The microstructure of the biochar particles loaded with the plant extract is as follows: Figure 6 As shown.

[0050] After soaking, drain the surface liquid through a 200-mesh filter (draining time 8 minutes), spread the loaded biochar evenly on a stainless steel tray (thickness 2.5cm), and dry it in a 70℃ oven for 5.5 hours, turning it over once every hour, with a final moisture content of 8%.

[0051] Approximately 26 kg of biochar loaded with plant extract was obtained (loading rate of approximately 30%). The biochar was dark brown in appearance, had a slight alfalfa odor, and felt dry and loose to the touch.

[0052] Step 3: Preparation of porous concrete bricks 3.1: Weigh the materials according to the following proportions (per cubic meter of concrete): 250 kg of PO 42.5 ordinary Portland cement, 1600 kg of crushed stone with a particle size of 10-15 mm, 3 kg of polycarboxylate superplasticizer, and 75 kg of water (water-cement ratio 0.30).

[0053] 3.2: First, dry mix the crushed stone in a forced mixer for 30 seconds.

[0054] 3.3: Add cement and continue dry mixing for 60 seconds.

[0055] 3.4: Dissolve the water-reducing agent in the mixing water, slowly add the dry material (water addition time is 90 seconds), stir for 3 minutes until the mixture is uniformly moistened.

[0056] 3.5: Pour the mixture into a steel mold (200mm×100mm×80mm) that has been pre-coated with machine oil. The mold structure is as follows: Figure 8 As shown; the mold has a pre-drilled filling groove and drainage holes. The filling groove is 72mm deep, 20mm long and wide, and has 10 drainage holes (spaced 30mm apart). The top view of the mold is shown below. Figure 9 As shown, the cross-section is as follows Figure 10 As shown.

[0057] 3.6: Vibration molding was performed using a vibration table for 45 seconds at a frequency of 55 Hz and an amplitude of 0.8 mm.

[0058] 3.7: Demold after curing at room temperature (20℃) for 24 hours.

[0059] 3.8: Cover the demolded bricks with a damp cloth, spraying water three times a day for the first 7 days, and once a day from day 8 to 28. Maintain a curing temperature of 20℃ and a relative humidity of 85%.

[0060] 3.9: Tested after 28 days of curing: porosity 25%, 28-day compressive strength 18.5 MPa, permeability coefficient 1.8 mm / s; the three-dimensional structure of the brick is as follows: Figure 2 As shown, the top view is as follows Figure 3 As shown, the cross-sectional structure is as follows Figure 4 As shown.

[0061] Step 4: Prepare the eco-friendly substrate 4.1: Prepare the ecological substrate according to the following mass ratio: 30% (3kg) biochar loaded with plant extract, 60% (6kg) planting soil (humus), and 10% (1kg) polyacrylate water-retaining agent. The composition of the ecological substrate is as follows: Figure 5 As shown.

[0062] 4.2: Pass the humus through a 5mm sieve to remove stones. Add the loaded biochar to the humus and mix thoroughly with a spatula for 8 minutes. Sprinkle the water-retaining agent evenly into the mixture and continue mixing for 8 minutes.

[0063] 4.3: Add water in batches and stir (approximately 1.5 kg of water) to adjust the moisture content to 20%, ideally forming a ball when squeezed in the hand and naturally crumbling when released.

[0064] 4.4: Approximately 11.5 kg of ecological substrate was obtained. It was dark brown in color, loose in texture, and had a slight soil and alfalfa odor.

[0065] Step 5: Filling and Laying 5.1: Inspect the porous concrete bricks to confirm that after 28 days of curing, there are no surface cracks and the strength is up to standard.

[0066] 5.2: Use a blower or compressed air to clean the dust and impurities on the surface and inside the pores of the brick to ensure that the eco-friendly substrate is in full contact with the internal pores of the brick.

[0067] 5.3: Fill the surface filling groove with ecological substrate: Use a small shovel to fill the filling groove with ecological substrate layer by layer, compacting it every 20mm (lightly press with the palm of your hand, compaction degree 75%), fill two layers in total, the filling groove is completely filled, and the surface is slightly lower than the brick surface by 3mm.

[0068] 5.4: Filling the internal pores of the brick with ecological substrate: Natural infiltration: After filling, let stand for 10 minutes. Some fine particles and loaded biochar particles will naturally infiltrate into the pores inside the brick through the permeable holes, with a penetration depth of about 15-20mm.

[0069] Assisted filling: Gently insert a bamboo skewer into each permeable hole (25mm depth) to promote the filling of the internal pores by the ecological substrate. Let it stand and cure for 3 hours, then cover with a damp cloth to retain moisture.

[0070] 5.5: Sow bermudagrass seeds on the surface of the eco-substrate at a density of 40g / m² (8g per brick). Cover the seeds with a thin layer (about 5mm) of eco-substrate and gently compact it.

[0071] 5.6: Laying vegetation bricks: Lay vegetation bricks at a slope ratio of 1:2 (vertical:horizontal), as shown in the following installation method. Figure 11 As shown; an 8mm gap is left between bricks 5. The gaps between the bricks are filled with eco-friendly substrate.

[0072] 5.7: After installation, spray water evenly using a sprayer (spray intensity 1.5 mm / min, spraying time 10 minutes) to fully moisten the eco-friendly substrate without water accumulation. The preparation process is as follows: Figure 7 As shown.

[0073] Spray water three times a day for the first three days (7:00 AM, 1:00 PM, and 6:00 PM), and spray water once a day from the fourth to the 30th day (7:00 AM).

[0074] Example 2: High-nutrient porous concrete bricks for vegetation (suitable for barren soils or rapid greening) The main difference between this embodiment and Embodiment 1 is: Step 1: Select 8 kg of legume (young soybean leaves) to prepare plant extract, with a material-to-liquid ratio of 1:12 (add 96 kg of water), an extraction temperature of 100℃, and an extraction time of 1.5 hours.

[0075] Approximately 86 kg of leachate was obtained. The leachate composition was: total nitrogen 16.8 g / L, total phosphorus 3.5 g / L, total potassium 8.2 g / L, and pH value 7.5.

[0076] Step 2: Use 15kg of straw charcoal (wheat straw, pyrolyzed at 500℃, particle size 2-8mm, specific surface area 350m² / g, porosity 48%) and mix it with 60kg of plant extract (material-to-liquid ratio 1:4, mass ratio), soak for 36 hours at 22℃.

[0077] The drying temperature was 65℃, the drying time was 6 hours, and the final moisture content was 9%.

[0078] Approximately 21 kg of biochar loaded with plant extract was obtained (loading of approximately 40%).

[0079] Step 3: Adjust the mix proportions of porous concrete to: 280 kg / m³ of PO 52.5 cement, 1500 kg / m³ of crushed stone with a particle size of 12-18 mm, 150 kg / m³ of medium sand (fine aggregate), 4 kg / m³ of naphthalene-based water-reducing agent, and 90 kg / m³ of water (water-cement ratio 0.32).

[0080] The brick dimensions are 300mm×150mm×100mm, the filling groove depth is 90mm, and there are 12 permeable holes (hole diameter 5mm, spacing 70mm).

[0081] Tested after 28 days of curing: porosity 20%, compressive strength 22.3MPa, permeability coefficient 1.3mm / s.

[0082] Step 4: Adjust the ecological substrate ratio to: 35% (7kg) loaded biochar, 55% (11kg) planting soil (garden soil), and 10% (2kg) starch graft copolymer water-retaining agent. Add Bacillus inoculant (2 × 10⁶ live bacteria) 8 200g (CFU / g) (1% of the total mass of the eco-material).

[0083] Microbial agent activation method: Dissolve 200g of microbial agent in 2kg of warm water (35℃), stir well, let stand for 3 hours to activate, then evenly sprinkle into the ecological substrate and mix. Adjust the moisture content to 22%.

[0084] Step 5: Select a mixture of tall fescue and bermudagrass seeds (1:1) and broadcast them at a density of 45g / m² (20g per brick).

[0085] The paving slope is 1:2.5, and the brick joints are 10mm apart. The complete preparation process of this embodiment is as follows: Figure 7 As shown.

[0086] Performance test results (after 90 days): Nutrient slow release period: 102 days; 60-day leaching rate: 58% lower than the control group; Vegetation survival rate: 95%; Vegetation coverage: 98%; Plant root depth: up to 62 mm, average 48 mm; Microbial activity (soil dehydrogenase activity): 65% higher than the control group.

[0087] Example 3: Grout-filled vegetation porous concrete brick (suitable for projects with high ecological function requirements) The main difference between this embodiment and Embodiment 1 is that step 5.4 uses the grouting method: Step 5.4: Fill the internal pores of the brick with ecological substrate (grouting method): 5.4.1: Prepare mud-like ecological substrate: Take 5kg of ecological substrate, add 1.5kg of water (adjust the moisture content to 30-35%), and stir thoroughly to form a mud-like consistency (the consistency should be such that it can be drawn with a 100ml syringe).

[0088] 5.4.2: Use a 100ml syringe (nozzle diameter 3mm) to extract the mud-like ecological substrate.

[0089] 5.4.3: Insert the nozzle into the permeable hole (insertion depth 20mm) and slowly inject the mud-like ecological substrate at a rate of 15ml / min until it seeps out from the pores at the bottom of the brick (the seepage amount is about 5-8ml). Inject about 40ml of mud-like ecological substrate into each permeable hole.

[0090] 5.4.4: After all 12 permeable holes have been filled (approximately 480ml in total), gently tap the surface of the brick 10 times with your palm to make the ecological substrate more evenly distributed in the internal pores.

[0091] 5.4.5: Let stand for 4 hours to cure, then cover with a damp cloth to keep moist.

[0092] The other steps are the same as in Example 1; the complete preparation process of this example is as follows: Figure 7 As shown.

[0093] Comparative Example 1 (Vegetated concrete bricks without biochar loading technology) The preparation method is the same as in Example 1, but steps 2 and 4 are different: Step 2: Do not prepare biochar loaded with plant extract; use ordinary rice husk char directly (unloaded).

[0094] Step 4: Ecological substrate ratio: 10% ordinary rice husk charcoal, 60% planting soil, 20% commercial organic fertilizer (NPK content 5-3-2), 10% water-retaining agent. Other steps are the same.

[0095] Performance test results (after 90 days): Nutrient slow-release period: 35 days (short slow-release period); 60-day leaching rate: baseline (100%); Vegetation survival rate: 67%; Vegetation coverage: 72%; Plant root depth: maximum 28mm, average 20mm Comparative Example 2 (without biochar) was prepared using the same method as Example 1, but steps 2 and 4 were different: Step 2: Do not prepare biochar loaded with plant extract.

[0096] Step 4: Ecological substrate ratio: planting soil: 70%; commercial organic fertilizer: 20%; water-retaining agent: 10%] Other steps are the same.

[0097] Comparative Example 3 (Plant extract added directly) The preparation method is the same as in Example 1, but steps 2 and 4 are different: Step 2: Instead of preparing biochar loaded with plant extract, the plant extract is added directly when preparing the ecological substrate in step 4.

[0098] Step 4: Ecological substrate preparation ratio: Ordinary rice husk charcoal: 10%; planting soil: 60%; water-retaining agent: 10%; plant extract: 20% (added directly). The other steps are the same.

[0099] Note: While direct addition of plant extracts is more effective than organic fertilizers, it is still not as effective as load-bearing technology.

[0100] Table 1. Performance comparison of planted concrete bricks in Implementation Cases 1-3 and Comparative Example 1-3:

[0101] The results of Examples 1-3 and Comparative Examples 1-3 show that the planted porous concrete brick of the present invention has significant advantages over traditional technologies: Extended nutrient slow-release period: The slow-release period of Examples 1-3 is 85-102 days, while the comparative examples are only 28-42 days. The technology of this invention extends the slow-release period by 2-3 times, meeting the long-term growth needs of plants.

[0102] Significantly reduced leaching rate: The 60-day leaching rate of Examples 1-3 was 52-65% lower than that of the control group, effectively reducing nutrient loss and environmental pollution risks, and improving nutrient utilization efficiency.

[0103] The survival rate of vegetation was greatly improved: the 90-day survival rate of Examples 1-3 reached 92-97%, while the comparative example was only 54-72%, an increase of 40-50%.

[0104] Higher vegetation coverage: The 120-day coverage of Examples 1-3 reached 95-99%, while the comparative example was only 65-80%, resulting in a better landscape effect.

[0105] The plant roots are more developed: the root depth of Examples 1-3 reaches 32-58mm, while the comparative example is only 18-24mm. The roots can penetrate deep into the brick to absorb nutrients and water, which enhances the bonding effect between the vegetation and the brick.

[0106] Stable engineering performance: The compressive strength of the bricks in all embodiments is ≥15MPa and the permeability coefficient is ≥1.0mm / s, which meets the engineering requirements and the requirements for sponge city construction.

[0107] Loading technology is superior to direct addition: Comparative Example 3 shows that although direct addition of plant extract is more effective than organic fertilizer, it is still not as good as loading technology, indicating that the adsorption and slow release effects of biochar are crucial to improving performance.

[0108] The ecological matrix layer with internal and external penetration has a significant effect: The ecological matrix filling rate of Example 3 (grouting filling method) is as high as 92%, and the indicators such as plant root depth, water holding capacity and erosion resistance are significantly better than those of conventional filling method, which proves the important role of the ecological matrix layer with internal and external penetration in improving the ecological function of planted bricks.

[0109] The above embodiments demonstrate that the present invention utilizes the technology of loading biochar with plant leachate and filling it into the internal pores of porous concrete bricks to form an ecological matrix layer that is interconnected inside and out. This effectively achieves the goals of slow nutrient release, reduced leaching, and promotion of vegetation survival, while maintaining the engineering performance of porous concrete. It has good application value and promotion prospects.

[0110] The above description is merely a preferred embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A plant-based porous concrete brick with biochar loaded with plant leachate, characterized in that, include: Porous concrete bricks with built-in vertical channels; Ecological substrate filling the channels; The porous concrete brick is prepared by cement, coarse aggregate, optional fine aggregate, water-reducing agent and water in a specified mass ratio. The brick has a porosity of 15-35%, a thickness of 50-120mm and a pore depth of 40-100mm. The side of the brick is provided with interlocking protrusions and interlocking grooves for splicing and positioning of adjacent bricks. The ecological substrate includes biochar loaded with plant extract, planting soil and water-retaining agent, and may optionally contain microbial agents.

2. The planted porous concrete brick according to claim 1, characterized in that, The cement is ordinary Portland cement (PO 42.5 or PO 52.5), the coarse aggregate particle size is 5-30mm, the fine aggregate particle size and fineness modulus are optional, and the water-reducing agent is polycarboxylic acid or naphthalene-based.

3. The planted porous concrete brick according to claim 1, characterized in that, The proportion of biochar loaded with plant extract in the ecological substrate is 20-40%, the proportion of planting soil is 50-70%, the proportion of water-retaining agent is 5-15%, and the proportion of microbial agent is 0-2%.

4. The planted porous concrete brick according to claim 3, characterized in that, The plant extract is derived from legumes, alfalfa, milkvetch, or a combination thereof, with total nitrogen of 5-20 g / L, total phosphorus of 1-5 g / L, total potassium of 3-10 g / L, and a pH of 6.5-7.

5.

5. The planted porous concrete brick according to claim 3, characterized in that, The biochar has a particle size of 1-10 mm, a specific surface area of ​​50-500 m² / g, and a porosity of ≥30%.

6. A method for preparing plant-based porous concrete bricks using plant leachate-loaded biochar, characterized in that, Includes the following steps: To prepare plant extracts, the tender stems and leaves of leguminous plants, alfalfa, milkvetch, or combinations thereof are extracted to obtain plant extracts. The biochar was mixed with the plant extract obtained in step 1 and allowed to stand for soaking to obtain biochar loaded with plant extract. Prepare porous concrete bricks according to the specified proportions and cure them for more than 28 days; To prepare the ecological substrate, mix the biochar loaded with plant extract obtained in step 2, planting soil, and water-retaining agent, and add microbial agents if necessary. The ecological substrate prepared in step 4 is filled into the pores and surface filling grooves of the porous concrete brick prepared in step 3. Sow plant seeds or plant seedlings, and water and care for them.

7. The method according to claim 6, characterized in that, In step 2, the soaking temperature is 15-25℃, the soaking time is 12-48 hours, and after soaking, the product is dried until the moisture content is ≤10%.

8. The method according to claim 6, characterized in that, Step 5 uses the grouting method to inject mud-like ecological substrate into the brick ducts, so that the duct filling rate is ≥90%, forming an internally and externally connected ecological substrate layer.

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