Anti-scouring ecological concrete formula for slope protection

Abstract

The invention relates to the technical field of concrete, in particular to an anti-scouring ecological concrete formula for slope protection. The concrete comprises the following raw materials: 420-480 kg of cement; the coarse aggregate is 840 kg to 960 kg; the fine aggregate is 460 kg to 540 kg; the weight of the biochar is 90 kg to 120 kg; 6 kg to 10 kg of sodium carboxymethyl cellulose; 4 kg to 5.6 kg of a water reducing agent; 170 kg to 200 kg of water; in the formula of the anti-scouring slope protection ecological concrete, the raw materials are used and prepared, so that the pore structure of the concrete is optimized by the biochar, the compactness is improved, and the anti-scouring performance is enhanced; the sodium carboxymethyl cellulose is combined with the biochar to form a protective film with viscosity and toughness, so that the impact force of water flow is effectively buffered, and the loss of the biochar and the abrasion of the surface of the concrete are reduced; meanwhile, the water reducing agent reduces the water consumption, the strength and durability of the concrete are improved, and the anti-scouring capacity is further enhanced; under long-term water flow scouring or rainstorm erosion, the concrete can effectively keep the structure stable, the surface abrasion and peeling risks are reduced, and the engineering maintenance cost and potential safety hazards are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and specifically, to a formula for erosion-resistant slope ecological concrete. Background Art

[0002] At present, in various slope protection projects, such as river bank slope protection in water conservancy projects, road slope protection in traffic projects, and landscape slope maintenance in municipal projects, concrete materials are widely used. However, traditional slope protection concrete materials have some deficiencies. On the one hand, traditional concrete is often a rigid structure with a low porosity, which is not conducive to plant growth, making it difficult to achieve the function of ecological slope protection, and may lead to the imbalance of the slope surface ecosystem and affect the landscape effect. On the other hand, its erosion resistance performance is limited. Under long-term water flow scouring or rainstorm erosion, the surface of the concrete is prone to wear, spalling and other phenomena, which will weaken the overall stability of the slope protection, increase the maintenance cost of the project and potential safety hazards.

[0003] For example, a concrete for slope protection blocks and a preparation method of slope protection blocks proposed in Chinese Patent Publication No.: CN108395169A. The slope protection block concrete prepared by this invention has certain strength and stability, and to a certain extent, improves the ecological performance of the slope protection, providing certain basic conditions for plant growth. However, in terms of ecological performance, although the prepared concrete has certain pores for some plants to take root, the pore distribution is not uniform enough and the connectivity is poor, resulting in limited growth space for plant roots.

[0004] From the perspective of erosion resistance performance, due to the problems of uneven pore distribution and poor connectivity of the above-mentioned concrete, the internal structure of the concrete is relatively weak. When scoured by water flow, the water flow is more likely to invade the interior of the concrete, accelerating the erosion of the concrete. At the same time, lacking a stable plant root network, the buffering effect of the grasping force and friction force of plant roots on the impact force of water flow cannot be utilized, resulting in the concrete surface directly bearing a large water flow force, which will not only accelerate the wear and spalling of the concrete surface, but also may cause the loosening and damage of the internal structure, thus reducing the long-term effectiveness and sustainability of the ecological slope protection and affecting the restoration and protection effect of the slope surface ecological environment.

[0005] In view of this, there is an urgent need for a formula for erosion-resistant slope ecological concrete. Summary of the Invention

[0006] The purpose of the present invention is to provide a formula for erosion-resistant slope ecological concrete to solve the problems raised in the above background art.

[0007] To achieve the above purpose, firstly, the present invention provides a formula for erosion-resistant slope ecological concrete, including the following raw materials:

[0008] Cement: 420 kg - 480 kg; Coarse aggregate: 840 kg - 960 kg, strengthening the skeleton structure of the concrete; Fine aggregate: 460 kg - 540 kg, filling the voids between the coarse aggregates and improving the workability of the concrete; Biochar: 90 kg - 120 kg, capable of enhancing the anti-scouring performance and ecological performance; Sodium carboxymethylcellulose: 6 kg - 10 kg, capable of combining with biochar to further improve the anti-scouring ability and improve water retention and other properties; Water reducing agent: 4 kg - 5.6 kg, reducing the water consumption of the concrete and improving the strength and durability of the concrete; Water: 170 kg - 200 kg;

[0009] Among them, the biochar is prepared from crop straws and starch-based hydrogels, forming a pore structure, which is used to enhance the density and anti-scouring property while providing nutrients for plant growth; The biochar combines with sodium carboxymethylcellulose to form a protective film with viscosity and toughness, which is used to buffer the impact force of water flow.

[0010] In the present invention, the biochar can optimize the pore structure of the concrete, improve the density, enhance the anti-scouring and ecological properties. The combination of sodium carboxymethylcellulose and biochar can buffer the impact of water flow, reduce material loss and wear, improve the water retention property and facilitate plant growth; Cement is combined with coarse and fine aggregates to build a stable skeleton, and the water reducing agent reduces the water consumption, improving the strength and durability; It not only effectively improves the anti-scouring ability, reduces the engineering maintenance cost and potential safety hazards, but also promotes the ecological restoration and balance of the slope, realizing ecological slope protection.

[0011] Second, according to Figure 1 as shown, the present invention provides a preparation method for an anti-scouring slope protection ecological concrete formula, including the following steps:

[0012] S1.1, Dry mixing: First, add cement, coarse aggregate, fine aggregate and biochar into a concrete mixer, start the mixer for dry mixing to make these solid raw materials fully and evenly mixed;

[0013] S1.2, Dissolving sodium carboxymethylcellulose and water reducing agent: Prepare two containers. Add 26% - 30% of the total water consumption into the first container, add sodium carboxymethylcellulose into the water, and stir at a stirring speed of 120 r / min - 180 r / min for 20 min - 30 min to make it fully dissolved to form a uniform solution; Then pour the remaining water and water reducing agent into the second container, and stir at a stirring speed of 160 r / min - 240 r / min for 6 min - 10 min to make the water reducing agent fully dissolved in the water;

[0014] S1.3, Wet Mixing: Sequentially add the dissolved sodium carboxymethyl cellulose solution and water reducing agent solution into a blender. Turn on the blender and mix at a stirring speed of 80 r / min - 120 r / min for 4 min - 6 min to fully mix all raw materials and form a concrete mixture.

[0015] S1.4, Pouring and Molding: Pour the mixed concrete mixture into a slope protection mold. Use a vibrator and adjust its vibration frequency to 6000 times / min - 10000 times / min for vibration operation to make the concrete dense and expel the internal air, thus obtaining a preliminarily formed anti-scour slope protection ecological concrete.

[0016] S1.5, Curing: Cure the formed concrete and sprinkle water 3 - 4 times a day to keep the concrete surface moist, thus obtaining the anti-scour slope protection ecological concrete.

[0017] In the present invention, through the preparation steps of the anti-scour slope protection ecological concrete formula, all raw materials can be fully mixed and reacted. Dry mixing can evenly disperse the solid raw materials. Dissolving sodium carboxymethyl cellulose and water reducing agent while controlling the mixing speed and time can make them fully dissolve and play their roles; wet mixing makes the raw materials deeply mixed and improves the performance of the concrete; vibration can improve the density of the concrete and increase the strength; curing promotes the hydration of cement.

[0018] Thirdly, as shown in Figure 2 the present invention also provides the preparation of biochar, including the following steps:

[0019] S2.1, Material Preparation: Crop straws 2 cm - 3 cm long and starch-based hydrogel (corn starch, acrylamide, N,N'-methylenebisacrylamide, potassium persulfate, deionized water), and the dosage ratio of crop straws to starch-based hydrogel is 5∶2.

[0020] S2.2, Mixing Materials: First, put the crop straws into a high-temperature resistant ceramic crucible, then add the starch-based hydrogel, and use a glass rod to stir for 15 min - 20 min to evenly mix the crop straws and the starch-based hydrogel.

[0021] S2.3, Pyrolysis Treatment: Put the ceramic crucible into a muffle furnace and heat it from room temperature at a rate of 5 °C / min until the temperature reaches 500 °C. Then, keep the temperature constant for pyrolysis for 2 h to make the raw materials fully react.

[0022] S2.4, Cooling and Taking out of the Furnace: After the muffle furnace cools down to room temperature by itself, take out the ceramic crucible containing the pyrolysis product.

[0023] S2.5, Cleaning and Drying: Transfer the pyrolysis product in the ceramic crucible to a glass beaker, rinse it repeatedly with deionized water for 5 - 7 times, then place the product in a petri dish and dry it in an oven at 105 °C until constant weight to obtain the required biochar.

[0024] In the present invention, through the preparation steps of biochar, the starch - based hydrogel can be fully mixed with crop straws and pyrolyzed, and the generated biochar has a rich pore structure. This can not only optimize the pores of concrete, enhance the density and erosion resistance, but also provide nutrients for plant growth and promote ecological restoration. When the components are combined, the polymer chains formed by the polymerization of acrylamide in the starch - based hydrogel and the carbon - containing structures generated by the pyrolysis of crop straws are combined together through physical entanglement and reactions between some active groups. For example, the hydroxyl group in the starch - based hydrogel reacts with the carboxyl group of the straw pyrolysis product to form an esterification reaction, and the reaction formula is: R - COOH + R ， - OH → R - COO - R ， + H2O (R, R ， represent different groups), enhancing the performance of biochar.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] 1. In the formula of the erosion - resistant slope - protection ecological concrete, through the dosage of each raw material and preparation, the biochar optimizes the pore structure of the concrete, improves the density, and enhances the erosion - resistant performance. Sodium carboxymethylcellulose combines with biochar to form a protective film with viscosity and toughness, effectively buffering the impact force of water flow, reducing the loss of biochar and surface wear of the concrete. At the same time, the water - reducing agent reduces the water consumption, improves the strength and durability of the concrete, and further enhances the erosion - resistant ability. Under long - term water flow erosion or heavy rain erosion, the concrete can effectively maintain the structural stability, reduce the risk of surface wear and spalling, and reduce the engineering maintenance cost and potential safety hazards.

[0027] 2. In the formula of the erosion - resistant slope - protection ecological concrete, the biochar is rich in minerals and trace elements, which can provide nutrients for plant growth, promote the development of plant roots. Its pore structure is also conducive to the rooting of plant roots, forming a stable root network to reinforce the slope surface. Sodium carboxymethylcellulose improves the water - retaining performance of the concrete. In addition, the components in this formula act synergistically to promote the material exchange and energy flow between the concrete and the surrounding ecological environment, accelerate the restoration and balance of the slope ecosystem, and achieve ecological slope protection. Description of the Drawings

[0028] Figure 1 is the flow chart of the preparation steps of the erosion - resistant slope - protection ecological concrete formula of the present invention;

[0029] Figure 2 is the flow chart of the preparation process of the biochar of the present invention;

[0030] Figure 3 It is the bar chart of the wear depth of the anti-scouring of the present invention;

[0031] Figure 4 It is the bar chart of the mass loss of the anti-scouring of the present invention;

[0032] Figure 5 It is the bar chart of the germination rate of the plants of the ecological property of the present invention;

[0033] Figure 6 It is the bar chart of the average growth height of the ecological property of the present invention;

[0034] Figure 7 It is the bar chart of the plant root penetration rate of the present invention;

[0035] Figure 8 It is the bar chart of the pore connectivity rate of the present invention. Specific embodiments

[0036] Next, in combination with the accompanying drawings in the present invention, the technical solutions in the embodiments of the present invention will be clearly and completely described. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those skilled in the art without creative efforts shall fall within the protection scope of the present invention.

[0037] The embodiment of the present invention provides a formula for anti-scouring slope protection ecological concrete, including the following raw materials:

[0038] Cement: 420 kg - 480 kg, as the cementitious material of the concrete, providing the strength basis; Coarse aggregate: 840 kg - 960 kg, the coarse aggregate is crushed stone, and the particle size of the crushed stone is 8 mm - 20 mm; Fine aggregate: 460 kg - 540 kg, the fine aggregate is river sand, and the particle size of the river sand is less than 4.5 mm; Biochar: 90 kg - 120 kg; Sodium carboxymethylcellulose: 6 kg - 10 kg; Water reducing agent: 4 kg - 5.6 kg; Water: 170 kg - 200 kg.

[0039] Among them, according to Figure 2 shown, the preparation of biochar includes the following steps:

[0040] S2.1. Material preparation: Crop straws 2 cm - 3 cm long and starch-based hydrogel; The dosage ratio of crop straws to starch-based hydrogel is 5:2 (for example: the dosage of crop straws is 500 g, and the dosage of starch-based hydrogel is 200 g); The starch-based hydrogel includes corn starch, acrylamide, crosslinking agent, initiator, deionized water, among which, the crosslinking agent uses N,N'-methylenebisacrylamide; The initiator uses potassium persulfate;

[0041] S2.2. Mixing materials: First, put the crop straw into a high-temperature resistant ceramic crucible, then add the starch-based hydrogel, and use a glass rod to stir for 15 - 20 minutes to evenly mix the crop straw and the starch-based hydrogel;

[0042] S2.3. Pyrolysis treatment: Put the ceramic crucible into a muffle furnace, heat it from room temperature at a rate of 5 °C / min until the temperature reaches 500 °C, and then keep the temperature constant for pyrolysis for 2 hours to make the raw materials fully react;

[0043] S2.4. Cooling and taking out of the furnace: After the muffle furnace cools down to room temperature by itself, take out the ceramic crucible containing the pyrolysis product;

[0044] S2.5. Cleaning and drying: Transfer the pyrolysis product in the ceramic crucible to a glass beaker, rinse it repeatedly with deionized water for 5 - 7 times to thoroughly remove the impurities and ash adhering to the surface of the pyrolysis product, then place the product in a petri dish and put it in an oven at 105 °C to dry to a constant weight, and the required biochar can be obtained.

[0045] In addition, the dosage of corn starch is 200 g; the dosage of acrylamide is 100 g; the dosage of N,N'-methylenebisacrylamide is 2 g; the dosage of potassium persulfate is 1 g; the dosage of deionized water is 1000 ml;

[0046] Among them, the starch-based hydrogel includes the following operation steps:

[0047] Add 200 g of corn starch to 500 ml of deionized water and stir evenly to form a starch paste. In another container, dissolve 100 g of acrylamide in 300 ml of deionized water and stir until completely dissolved, then add 2 g of N,N'-methylenebisacrylamide and 1 g of potassium persulfate and stir to dissolve them. Then slowly pour the acrylamide mixed solution into the starch paste while stirring, and then add the remaining 200 ml of deionized water and continue to stir evenly. Then transfer the mixed solution to a mold and seal it, react in a water bath at 60 °C for 3 hours to obtain the starch-based hydrogel. Finally, take out the hydrogel after the reaction and rinse it repeatedly with deionized water to remove the unreacted substances, so as to finally obtain the starch-based hydrogel

[0048] According to Figure 1 As shown, the embodiment of the present invention provides a preparation method of an anti-scouring slope protection ecological concrete formula, including the following steps:

[0049] S1.1. Dry mixing: First, add cement, coarse aggregate, fine aggregate and biochar to a concrete mixer, turn on the mixer for dry mixing, and the dry mixing speed of the mixer is 60 r / min - 100 r / min, and the mixing time is 2 - 3 minutes to fully mix these solid raw materials evenly;

[0050] S1.2. Dissolve sodium carboxymethylcellulose and water reducer: Prepare two containers. Add water accounting for 26%-30% of the total water consumption to the first container. Add sodium carboxymethylcellulose to the water and stir at a stirring speed of 120 r / min - 180 r / min for 20 min - 30 min to fully dissolve it and form a uniform solution. Then pour the remaining water and water reducer into the second container and stir at a stirring speed of 160 r / min - 240 r / min for 6 min - 10 min to fully dissolve the water reducer in the water.

[0051] S1.3. Wet mixing: Add the dissolved sodium carboxymethylcellulose solution and water reducer solution to the mixer in sequence. Start the mixer and stir at a stirring speed of 80 r / min - 120 r / min for 4 min - 6 min to fully mix all the raw materials and form a concrete mixture.

[0052] S1.4. Pouring and molding: Pour the mixed concrete mixture into the slope protection mold. Use a vibrator and adjust its vibration frequency to 6000 times / min - 10000 times / min for vibration operation to make the concrete dense and discharge the air inside, and then the preliminarily formed anti-scour slope protection ecological concrete can be obtained.

[0053] S1.5. Curing: Cure the formed concrete. The curing is carried out in an environment with a temperature of 20±2°C and a relative humidity greater than 90%. The curing days are 28 days - 46 days, and sprinkle water 3 - 4 times a day to keep the concrete surface moist, and then the anti-scour slope protection ecological concrete can be obtained.

[0054] In the present invention, first, by controlling the dosage of each raw material and following a series of preparation steps including dry mixing, dissolution, wet mixing, pouring and molding, and curing, the raw materials are fully mixed and reacted. It can not only optimize the pore structure of the concrete by relying on biochar, improve the density of the concrete, and thus enhance its anti-scour performance, but also utilize the minerals and trace elements rich in biochar to provide nutrients for plant growth and effectively promote the restoration and balance of the slope ecosystem. At the same time, sodium carboxymethylcellulose and biochar are combined with each other, which can effectively buffer the impact force during water flow scouring, reduce the loss of biochar and the abrasion of the concrete surface, and improve the water retention performance of the concrete. For example, the biochar prepared by pyrolysis after mixing starch-based hydrogel and crop straw has a pore structure, which can not only further optimize the pores in the concrete, enhance the density and anti-scour property of the concrete, but also better promote plant growth through its synergistic effect with other components in the concrete, thus effectively improving the effect of slope ecological restoration.

[0055] In addition, when sodium carboxymethylcellulose combines with biochar, it can form a protective film with viscosity and toughness on the surface of biochar, effectively buffering the impact force during water flow scouring, reducing the loss of biochar and the abrasion of the concrete surface, and enhancing the anti-scouring ability. At the same time, its water retention performance improves the humidity environment of the concrete, which is beneficial to plant growth and promotes slope ecological restoration. The reaction mechanism is mainly that the carboxyl group (-COOH) in the sodium carboxymethylcellulose molecule reacts with the hydroxyl group (-OH) on the surface of biochar to form an ester bond (-COO-), and there are also hydrogen bonds and other interactions between molecules, enhancing the binding force. The esterification reaction formula can be expressed as: Bio-O-CO-CMC + H2O (where Bio represents the biochar matrix and CMC represents the sodium carboxymethylcellulose matrix). Through these effects, the two are tightly combined, improving the comprehensive performance of the concrete.

[0056] By using the dosages of various raw materials and carrying out the preparation, the biochar optimizes the pore structure of the concrete, improves the density, and enhances the anti-scouring performance. Sodium carboxymethylcellulose combines with biochar to form a protective film with viscosity and toughness, effectively buffering the water flow impact force, reducing the loss of biochar and the abrasion of the concrete surface. At the same time, the water reducer reduces the water consumption, improves the strength and durability of the concrete, and further enhances the anti-scouring ability. Under long-term water flow scouring or rainstorm erosion, this concrete can effectively maintain the structural stability, reduce the risks of surface abrasion and spalling, and reduce the engineering maintenance cost and safety hazards.

[0057] Biochar is rich in minerals and trace elements, which can provide nutrients for plant growth and promote the development of plant roots. Its pore structure is also conducive to the rooting of plant roots, forming a stable root network to reinforce the slope. Sodium carboxymethylcellulose improves the water retention performance of the concrete. In addition, the components in this formula act synergistically to promote the material exchange and energy flow between the concrete and the surrounding ecological environment, accelerating the restoration and balance of the slope ecological system and realizing ecological slope protection.

[0058] According to different dosages of raw materials, the ecological slope protection concrete provided by the present invention is further described through the following specific embodiments.

[0059] Example 1

[0060] The raw material dosage of the erosion-resistant slope protection ecological concrete in this embodiment is as follows: 420 kg of cement; 840 kg of coarse aggregate (crushed stone, particle size 8 mm - 20 mm); 460 kg of fine aggregate (river sand, particle size less than 4.5 mm); 105 kg of biochar; 6 kg of sodium carboxymethylcellulose; 4 kg of water reducing agent; 170 kg of water. During preparation, biochar preparation is carried out first. Prepare 500 g of crop straw with a length of 2 cm - 3 cm and 200 g of starch-based hydrogel (including 200 g of corn starch, 100 g of acrylamide, 2 g of N,N'-methylenebisacrylamide, 1 g of potassium persulfate, and 1000 ml of deionized water), and obtain biochar after mixing and pyrolysis. Then, concrete preparation is carried out. Dry mixing is carried out in sequence (the mixer speed is 60 r / min, and the mixing time is 2 min), sodium carboxymethylcellulose and the water reducing agent are dissolved (the first container uses 26% of the total water consumption, the stirring speed is 120 r / min, and the stirring time is 20 min; the stirring speed of the second container is 160 r / min, and the stirring time is 6 min), wet mixing (the stirring speed is 80 r / min, and the stirring time is 4 min), casting and molding (the vibration frequency is 6000 times / min), and curing (the temperature is 20 ± 2 °C, the relative humidity is greater than 90%, the curing time is 28 days, and water is sprinkled 3 times a day).

[0061] Example 2

[0062] The raw material dosage of the erosion-resistant slope protection ecological concrete in this example is as follows: 450 kg of cement; 900 kg of coarse aggregate; 500 kg of fine aggregate; 95 kg of biochar; 10 kg of sodium carboxymethylcellulose; 4.8 kg of water reducing agent; 185 kg of water. The steps of biochar preparation and concrete preparation are similar to those in Example 1. The differences are that the dry mixing speed is 80 r / min and the mixing time is 2.5 min; when dissolving sodium carboxymethylcellulose, the first container uses 28% of the total water consumption, the stirring speed is 150 r / min, and the stirring time is 25 min. When dissolving the water reducing agent, the stirring speed of the second container is 200 r / min and the stirring time is 8 min; the wet mixing speed is 100 r / min and the mixing time is 5 min; the vibration frequency is 8000 times / min; the curing days are 35 days, and water is sprinkled 4 times a day.

[0063] Example 3

[0064] In the formula of the erosion-resistant slope protection ecological concrete of this embodiment, the dosages of each raw material are as follows: 480 kg of cement; 960 kg of coarse aggregate; 540 kg of fine aggregate; 120 kg of biochar; 8 kg of sodium carboxymethylcellulose; 5.6 kg of water reducer; 200 kg of water. During the preparation of biochar and concrete, the dry mixing speed is 100 r / min and the mixing time is 3 min; when dissolving sodium carboxymethylcellulose, 30% of the total water consumption is used in the first container, the mixing speed is 180 r / min, and the mixing time is 30 min. When dissolving the water reducer, the mixing speed in the second container is 240 r / min and the mixing time is 10 min; the wet mixing speed is 120 r / min and the mixing time is 6 min; the vibration frequency is 10,000 times / min; the curing days are 46 days, and water is sprinkled 4 times a day.

[0065] Table 1 Dosages of Each Raw Material in Examples 1-3

[0066] Example 1 Example 2 Example 3 Cement (kg) 420 450 480 Coarse aggregate (kg) 840 900 960 Fine aggregate (kg) 460 500 540 Biochar (kg) 105 95 120 Sodium carboxymethyl cellulose (kg) 6 10 8 Water reducing agent (kg) 4 4.8 5.6 Water (kg) 170 185 200

[0067] In order to verify that the slope protection ecological concrete prepared in the embodiment of the present invention has good erosion resistance and ecological properties, the following test examples are used to illustrate the slope protection ecological concrete provided in the embodiment of the present invention.

[0068] Test Example

[0069] The purpose of this test group is to explore the influence of different component ratios on the slope protection ecological concrete, and to detect the erosion resistance, ecological properties, plant root penetration rate and pore connectivity rate of the slope protection ecological concrete of the present invention.

[0070] Test Objectives: Test Group A, Test Group B and Test Group C respectively adopt the component ratios of the slope protection ecological concrete provided in Examples 1-3; the control examples adopt Control Group A, Control Group B, Control Group C and Control Group D, where:

[0071] Control Group A

[0072] Adopt the traditional slope protection concrete formula, and the raw materials are mainly 500 kg of cement, 1000 kg of coarse aggregate (crushed stone), 500 kg of fine aggregate (river sand), and 200 kg of water. Biochar, sodium carboxymethylcellulose and water reducer are not added. During preparation, cement, coarse aggregate and fine aggregate are added to the mixer and dry-mixed evenly, then water is added for wet mixing. After mixing evenly, it is poured into the slope protection mold, vibrated and formed with a vibrator, and then cured at room temperature for 28 days.

[0073] Control Group B

[0074] The formula includes 440kg cement, 880kg coarse aggregate, 480kg fine aggregate, 175kg water, 4.4kg water reducer, and 100kg common additive (similar to ceramsite, which plays a certain role in pore filling). During preparation, each raw material is added to the mixer in order and stirred evenly, then poured into shape and cured for 28 days in an environment with a temperature of about 20℃ and suitable humidity.

[0075] Control group C

[0076] The concrete formula and preparation method are the same as those in Example 1, but sodium carboxymethyl cellulose is not added.

[0077] Control group D

[0078] The concrete formula and preparation method were the same as those in Example 1, but no starch-based hydrogel was added to the biochar.

[0079] Test method: According to the present invention, the anti-scouring property, ecological property, plant root penetration rate and pore connectivity of the slope protection ecological concrete are tested respectively. The specific test methods are as follows:

[0080] The anti-scouring test method is as follows: a special water flow scouring test tank is used to fix concrete specimens of different groups with a size of 300mm×300mm×100mm at specific positions in the test tank; the water flow velocity is set to 2.5m / s, the water flow direction is at a 45° angle to the specimen surface, and the scouring time lasts for 36 hours; after the test, the wear depth of the concrete specimen surface is measured using a high-precision measuring instrument, and the mass loss of the specimen is accurately measured by a weighing device. The wear depth and mass loss are used as evaluation indicators. The shallower the wear depth and the smaller the mass loss, the stronger the anti-scouring performance of the concrete.

[0081] Ecological test method: select grass seeds of the same variety, specification and similar germination rate, and sow them evenly in the planting holes pre-opened on the surface of concrete specimens of different groups, sowing 5 seeds in each planting hole; place the specimens in an incubator simulating the natural environment, maintain the temperature at 25±2℃, relative humidity at 70%-80%, light intensity at 2000-3000Lux, and lighting time at 12 hours / day; after 60 days of incubation, count the number of seeds germinated on each specimen and calculate the germination rate; measure the average growth height of the germinated plants; comprehensively consider the indicators of germination rate and growth height to quantitatively evaluate the ecological performance of concrete. The higher the germination rate and the better the plant growth condition, the better the ecological performance.

[0082] Test method for plant root penetration rate: Plant the selected plant variety on the surface of the concrete specimen and cure for 90 days to ensure normal plant growth. After the curing period ends, cut the concrete specimen into 4 equal pieces vertically, and randomly select 5 observation points on the cut surface of each specimen. Use measuring tools to measure the depth of plant roots penetrating the concrete at each observation point, and count the number of penetrating roots. Calculate the plant root penetration rate according to the formula: Plant root penetration rate = (total sum of root penetration depths / total sum of concrete specimen thicknesses × total number of observation points) × 100%. The higher the penetration rate, the more conducive the concrete is to the growth and penetration of plant roots, and the better its ecological friendliness.

[0083] Test method for pore connectivity rate: Use a high-precision industrial CT scanner to perform a full-range scan of concrete specimens in different groups to obtain high-resolution pore structure images inside the specimens. Import the scanned images into professional image processing and analysis software, and use the software's algorithms to identify, segment, and analyze the pores. Calculate the volume of connected pores and compare it with the total pore volume of the specimen to obtain the pore connectivity rate, that is: Pore connectivity rate = (volume of connected pores / total pore volume) × 100%. The higher the pore connectivity rate, the more reasonable the pore structure inside the concrete, which is conducive to the transmission and growth of water, air, and plant roots inside the concrete, and has a better effect on the ecological slope protection function.

[0084] The specific detection indicators are shown in Table 2.

[0085] Table 2 Detection indicators of each sample

[0086]

[0087] According to Figures 3 - 8 and Table 2, the summary of the above comparison data is as follows:

[0088] Anti-scouring performance: The anti-scouring performance of experimental groups A, B, and C of the present invention is higher than that of each control group. The wear depth of experimental groups A, B, and C is between 0.6 mm and 1.0 mm, and the mass loss is between 0.2 kg and 0.4 kg. While control group A, as traditional concrete, has a wear depth of 4.0 mm and a mass loss of 2.5 kg, with poor anti-scouring ability. Control group B adds ordinary additives similar to ceramsite, with a wear depth of 3.0 mm and a mass loss of 1.5 kg, showing limited improvement. Control group C does not add sodium carboxymethylcellulose, with a wear depth of 2.0 mm and a mass loss of 1.0 kg. Control group D does not add starch-based hydrogel in the biochar, with a wear depth of 1.8 mm and a mass loss of 0.8 kg. This shows that the biochar in the formula of the present invention optimizes the pore structure and improves the density, sodium carboxymethylcellulose and biochar combine to form a protective film to buffer the impact of water flow, and the water reducer reduces the water consumption to improve the strength and durability. The components work together to significantly enhance the anti-scouring performance.

[0089] Ecological performance: The germination rates of plants in experimental groups A, B, and C were between 88% and 92%, and the average growth heights were between 16 cm and 22 cm, which were higher than those of the control group. Due to the low porosity of traditional concrete in control group A, the germination rate was only 36%, and the average growth height was 4 cm, with poor ecological performance. The ordinary additives added in control group B had no obvious improvement in ecological performance, with a germination rate of 48% and an average growth height of 6 cm. Control group C lacked sodium carboxymethylcellulose and had insufficient water retention and other properties, with a germination rate of 72% and an average growth height of 10 cm. The performance of the biochar in control group D was weakened due to the absence of starch-based hydrogel, with a germination rate of 76% and an average growth height of 11 cm. It shows that the biochar in the formula of the present invention provides nutrients, and its pores are beneficial for rooting. Sodium carboxymethylcellulose improves the water retention performance, which is more conducive to plant growth and realizes a good ecological slope protection function.

[0090] Plant root penetration rate: The plant root penetration rates of experimental groups A, B, and C were 62%, 67%, and 72% respectively, which were much higher than 18% of control group A, 25% of control group B, 42% of control group C, and 47% of control group D. This reflects that the biochar and sodium carboxymethylcellulose in the concrete of the present invention jointly optimize the internal structure, enabling plant roots to have better penetration conditions, which is conducive to the formation of a stable root network to reinforce the slope. Due to the lack or insufficiency of components in each control group, it is not conducive to root penetration.

[0091] Pore connectivity rate: The pore connectivity rates of experimental groups A, B, and C were between 46% and 52%, which were higher than 18% of control group A, 22% of control group B, 32% of control group C, and 38% of control group D. It shows that the pore structure of the biochar in the formula of the present invention and its synergistic effect with other components, as well as the optimization of the pore structure by sodium carboxymethylcellulose, etc., make the internal pore structure of the concrete more reasonable, which is conducive to the transmission and growth of water, air, and plant roots, improving the ecological slope protection function. The pore connectivity of each control group is poor.

[0092] In summary, the anti-scour slope protection ecological concrete formula of the present invention effectively reduces wear and mass loss in anti-scour performance through the synergistic cooperation of some components such as biochar, sodium carboxymethylcellulose, and water reducer, reducing the engineering maintenance cost and potential safety hazards; in ecological performance, it promotes plant growth, root penetration, and the formation of a reasonable pore structure, accelerating the repair and balance of the slope ecosystem, thus achieving a high-performance ecological slope protection effect.

[0093] The foregoing has shown and described the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited by the above embodiments. The above embodiments and the descriptions in the specification are only preferred examples of the present invention and are not used to limit the present invention. Without departing from the spirit and scope of the present invention, the present invention will have various changes and improvements, and these changes and improvements all fall within the scope of the present invention claimed. The scope of the present invention claimed is defined by the appended claims and their equivalents.

Claims

1. A formula of anti-scour slope protection ecological concrete, characterized in that: Including the following ingredients: Cement: 420kg-480kg; coarse aggregate: 840kg-960kg; Fine aggregate: 460kg-540kg; Biochar: 90kg-120kg; Sodium carboxymethyl cellulose: 6kg-10kg; Water reducing agent: 4kg-5.6kg; Water: 170kg-200kg; The biochar is prepared from crop straw and starch-based hydrogel to form a porous structure, which is used to enhance density and scour resistance while providing nutrients for plant production; the biochar is combined with sodium carboxymethyl cellulose to form a protective film with stickiness and toughness to buffer the impact of water flow.

2. The anti-scour slope protection ecological concrete formula according to claim 1 is characterized in that: The coarse aggregate is crushed stone, and the particle size of the crushed stone is 8mm-20mm; the fine aggregate is river sand, and the particle size of the river sand is less than 4.5mm.

3. The anti-scour slope protection ecological concrete formula according to claim 1 is characterized in that: It also includes a preparation method, the specific steps are as follows: S1.1, dry mixing: first add cement, coarse aggregate, fine aggregate and biochar into a concrete mixer, turn on the mixer for dry mixing, so that these solid raw materials are fully mixed; S1.

2. Dissolve sodium carboxymethyl cellulose and water reducer: prepare two containers, add 26%-30% of the total water volume into the first container, add sodium carboxymethyl cellulose into the water, stir at a stirring speed of 120r / min-180r / min for 20min-30min to fully dissolve it and form a uniform solution; then pour the remaining water and water reducer into the second container, stir at a stirring speed of 160r / min-240r / min for 6min-10min to fully dissolve the water reducer in the water; S1.3, wet mixing: add the dissolved sodium carboxymethyl cellulose solution and water reducing agent solution into the mixer in sequence, turn on the mixer, and stir at a stirring speed of 80r / min-120r / min for 4min-6min to fully mix all the raw materials to form a concrete mixture; S1.4, casting and molding: pour the stirred concrete mixture into the slope protection mold, use a vibrator, adjust the vibration frequency to 6000 times / min-10000 times / min to perform vibration operations, make the concrete dense, and discharge the internal air, so as to obtain the preliminary formed anti-scour slope protection ecological concrete; S1.

5. Maintenance: Maintain the formed concrete and sprinkle water 3-4 times a day to keep the concrete surface moist to obtain erosion-resistant slope protection ecological concrete.

4. The anti-scour slope protection ecological concrete formula according to claim 3 is characterized in that: In S1.1, the dry stirring speed of the stirrer is 60 r / min-100 r / min, and the stirring time is 2-3 min.

5. The anti-scour slope protection ecological concrete formula according to claim 3 is characterized in that: In S1.5, the curing is carried out in an environment with a temperature of 20±2° C. and a relative humidity greater than 90%, and the curing days are 28 days to 46 days.

6. The anti-scour slope protection ecological concrete formula according to claim 1 is characterized in that: The preparation of the biochar comprises the following steps: S2.

1. Material preparation: 2cm-3cm long crop straw and starch-based hydrogel; S2.2, mixing materials: firstly put the crop straw into a high temperature resistant ceramic crucible, then add the starch-based hydrogel, and stir with a glass rod for 15-20 minutes to evenly mix the crop straw and the starch-based hydrogel; S2.3, pyrolysis treatment: put the ceramic crucible into a muffle furnace, and heat it from room temperature at a rate of 5°C / min until the temperature reaches 500°C, and then maintain the temperature for 2 hours to allow the raw materials to fully react; S2.4, cooling and removing from the furnace: After the muffle furnace is cooled to room temperature, take out the ceramic crucible containing the pyrolysis product; S2.

5. Cleaning and drying: transfer the pyrolysis product in the ceramic crucible to a glass beaker, rinse it repeatedly with deionized water for 5-7 times, place the product in a culture dish, and dry it in an oven at 105°C to constant weight to obtain the required biochar.

7. The anti-scour slope protection ecological concrete formula according to claim 6 is characterized in that: In the S2.1, the ratio of the crop straw to the starch-based hydrogel is 5:

2.

8. The anti-scour slope protection ecological concrete formula according to claim 6 is characterized in that: In S2.1, the starch-based hydrogel comprises corn starch, acrylamide, a cross-linking agent, an initiator, and deionized water.

9. The anti-scour slope protection ecological concrete formula according to claim 8, characterized in that: The cross-linking agent is N,N'-methylenebisacrylamide; the initiator is potassium persulfate.

10. The anti-scour slope protection ecological concrete formula according to claim 9, characterized in that: The amount of corn starch used is 200g; the amount of acrylamide used is 100g; the amount of N,N'-methylenebisacrylamide used is 2g; the amount of potassium persulfate used is 1g; and the amount of deionized water used is 1000ml.

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