Method for preparing enhanced low-carbon oil-absorbing pervious vegetation concrete

Abstract

The invention provides a method for preparing enhanced low-carbon oil-absorbing vegetation pervious concrete, and relates to the technical field of ecological building materials, and the method comprises the following steps: respectively treating coarse aggregate and shell powder, determining the use amount of a water reducing agent in the concrete by using a jumping table fluidity test, and adding a water reducing agent into the concrete; the preparation method comprises the following steps: sequentially adding mixing water, coarse aggregate, fly ash, slag, cement, modified shell powder, a mixed solution of a water reducing agent and mixing water and a mixed solution of silane and mixing water into a stirrer, and carrying out staged stirring and layered die filling and tamping to obtain the enhanced low-carbon oil-absorption pervious concrete for vegetation. According to the invention, 60-80% of cement is replaced by the fly ash and the slag to form a cementing material, and the nano reinforcement effect of the acid-base modified shell powder and a coarse aggregate interface optimization process are combined, so that the mechanical property of the concrete is improved, and the compressive strength of 60 days reaches more than 15 Mpa. The strength of the vegetation pervious concrete is improved while high water permeability, oil absorption capacity and vegetation function are guaranteed, and the vegetation pervious concrete is suitable for high-load ecological engineering scenes.

Description

Technical Field

[0001] The present invention relates to the technical field of ecological building materials, and in particular to a method for preparing enhanced low-carbon oil-absorbing vegetation-based permeable concrete. Background Art

[0002] As a green building material that combines ecological restoration and stormwater management functions, vegetated permeable concrete has important application value in areas such as ecological slope protection and sponge city construction. However, in practical applications, traditional vegetated permeable concrete generally suffers from insufficient mechanical strength. Especially under long-term loads or complex environments (such as oil erosion), its durability and stability cannot meet engineering requirements. This deficiency is mainly due to two technical bottlenecks: First, the coarse aggregate interface has weak bonding properties. In traditional production processes, coarse aggregate is often prepared using simple mechanical screening, without removing surface contaminants (such as dust and clay). These residual contaminants affect interfacial properties in two ways: first, they form a physical barrier on the aggregate surface, significantly reducing the chemical bonding between the aggregate and the cementitious material; second, the contaminant coverage weakens the microscopic roughness of the aggregate surface, preventing the cement paste from forming a complete coating. These dual effects together lead to structural defects in the interfacial transition zone, ultimately resulting in a significant reduction in the macroscopic mechanical properties of concrete.

[0003] Second, the fluidity of cementitious materials is not precisely controlled. Vegetated permeable concrete relies on the uniform filling and bonding of cementitious materials between coarse aggregates, but the existing technology often adjusts the water-reducing agent dosage based on experience, resulting in excessively high or low fluidity of the cementitious materials. When the fluidity is too high, the cementitious materials are prone to sedimentation and loss, and the effective bonding between aggregates is reduced; when the fluidity is too low, the cementitious materials are difficult to fully wrap the aggregates, resulting in uneven internal porosity, which further weakens the mechanical properties. In addition, the active utilization rate of conventional mineral admixtures (such as fly ash and slag) is low, and there is a lack of modification design for oil absorption function, making it difficult to synergistically improve the mechanical and functional properties of concrete.

[0004] To address the above problems, it is urgent to optimize the coarse aggregate processing technology and precisely control the fluidity of cementitious materials, improve the interface structure between aggregate and cementitious materials, and introduce functional modified materials to significantly improve the mechanical strength and environmental adaptability of concrete while ensuring permeability and vegetation capacity. Summary of the Invention

[0005] In order to address the deficiencies of the above-mentioned prior art, the purpose of the present invention is to provide a method for preparing enhanced low-carbon oil-absorbing and vegetation-supported permeable concrete. First, the coarse aggregate is graded and screened, washed with high-pressure water, and soaked for dust removal to optimize the physical properties and interface state of the coarse aggregate and enhance the cohesiveness of the coarse aggregate interface. Shell powder is subjected to gradient acid-base treatment using sodium citrate solution and NaOH solution of different mass fractions to activate the surface properties of the shell powder. Then, the amount of water reducer in the concrete is determined using a table fluidity test to improve the accuracy of fluidity control of the cementitious material. Finally, the coarse aggregate, modified shell powder, water reducer, and other components obtained above are sequentially added to a mixer. By staged stirring and layered mold filling and tamping, enhanced low-carbon oil-absorbing and vegetation-supported permeable concrete is obtained. Fly ash and slag are used to replace 60% to 80% of the cement to form a cementitious material. The nano-enhancement effect of the acid-base modified shell powder and the coarse aggregate interface optimization process are combined to ultimately improve the mechanical properties of the concrete.

[0006] Specifically, on the one hand, the present invention provides a method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete, which comprises the following steps: S1. First, the coarse aggregate is graded, then the coarse aggregate treated with a high-pressure water gun is soaked in water with intermittent stirring during the soaking period, and finally dried and again screened using a vibrating screen to obtain a coarse aggregate with a particle size of 5-10 mm; S2, first crushing and sieving the dried shells with a wall breaking machine to obtain shell powder with a particle size of 0.3-0.6 mm, then soaking them in sodium citrate solution and NaOH solution with different mass fractions, and finally treating them at high temperature to obtain modified shell powder; S3. First, determine the control range of the benchmark cementitious material and equivalent fluidity under the optimal working state of concrete; then, the water reducer dosage is 0.5 parts by weight as the initial dosage, and then the water reducer is added in a gradient of 0.1 parts to perform a fluidity matching test. The specific process is: first, a certain weight of cement, fly ash, slag and modified shell powder are stirred at a speed of 140 r / min for 30 seconds in a mixing pot to obtain a premixed liquid, then a mixture consisting of a water reducer and 70% mixing water is added and stirred at a speed of 140 r / min for 60 seconds, then stirred at a speed of 285 r / min for 30 seconds, and then a mixture consisting of silane and 30% mixing water is added. After standing for 90 seconds, the mixture is stirred at a speed of 285 r / min for 90 seconds to obtain a cementitious material; finally, the gel material after mold installation is jumped using a jumping table instrument to obtain the dosage of the water reducer; S4. Add mixing water, coarse aggregate, fly ash, slag, cement, modified shell powder, a mixture of water reducer and mixing water, and a mixture of silane and mixing water into the mixer in sequence, and obtain enhanced low-carbon oil-absorbing and vegetation-based permeable concrete through staged mixing and layered mold filling and tamping.

[0007] Preferably, the specific process of preparing the enhanced low-carbon oil-absorbing vegetation-permeable concrete in step S4 is as follows: S41. First, 30% of the mixing water and coarse aggregate were poured into a mixer and stirred for 60 seconds. Then, a certain amount of fly ash, slag, cement and modified shell powder were added in sequence and stirred for 90 seconds to obtain an intermediate premix. S42. On the basis of step S41, a mixture consisting of the amount of water reducer determined in step S3 and 50% of mixing water is added and stirred for 60 seconds, and then a mixture consisting of silane and 20% of mixing water is added and stirred for 150 seconds to obtain a concrete mixture; S43. Divide the obtained concrete mixture into three layers of molds. Use a 2 cm diameter round tamping rod to tamp each layer from the outside to the inside 25 times, and tap the bottom of the mold 3 to 5 times alternately from left to right. After the last layer is completed, use a scraper to level the surface. Finally, place the mixture in a curing box at 20 ± 2 ℃ and 95% humidity for 72 hours before demolding. After demolding, continue to cure until the design age.

[0008] Preferably, in step S3, if the fluidity F of the gelling material measured in the test is 实测 If the diameter exceeds 185~195 mm, the water reducing agent dosage needs to be adjusted. The target dosage is C 目标 The expression is as follows: ; Where: F 目标 The target fluidity is 190 mm, which is the median value of the equivalent range of 185 to 195 mm, or fine-tuned according to actual needs. 实测 is the measured fluidity at the current water reducer dosage, C 当前 is the dosage of water reducer in the current test.

[0009] Preferably, in step S3, the linear model of fluidity and water-reducing agent dosage is expressed as follows: ; Where: F is the measured fluidity of the cementitious material, C is the amount of water reducer, k is the influence coefficient of the water reducer dosage on fluidity, and b is the intercept of the linear model.

[0010] Preferably, in step S2, the NaOH solution is 95% analytically pure and solid NaOH particles, and the sodium citrate solution is 95% analytically pure and solid sodium citrate particles.

[0011] Preferably, in step S31, the stirring speed of the stirring pot varies within a range of ±5 r / min at 140 r / min, and within a range of ±10 r / min at 285 r / min.

[0012] Preferably, in step S31, the mixture consisting of the water reducer and 70% of mixing water and the mixture consisting of the silane and 30% of mixing water are both obtained by stirring for 30 seconds using a magnetic stirrer.

[0013] Preferably, in step S31, after stirring at a speed of 285 r / min for 90 s, if agglomeration occurs in the stirring pot, the stirring pot is further stirred at a speed of 285 r / min for 15 s.

[0014] On the other hand, the present invention provides a concrete obtained by a method for preparing enhanced low-carbon oil-absorbing and vegetation-based permeable concrete, which includes coarse aggregate, cement, fly ash, slag, modified shell powder, water reducer, silane and mixing water, and the components are calculated by weight as follows: 1450~1550 parts of coarse aggregate, 140~450 parts of cement, 0~70 parts of fly ash, 0~15 parts of slag, 0~35 parts of modified shell powder, 0~5 parts of silane, 0~7 parts of water reducer, and 60~150 parts of mixing water.

[0015] Preferably, the coarse aggregate is granite gravel with a particle size of 5 to 10 mm, the shell is a scallop or a mussel, the water reducer is a polycarboxylic acid-based high-performance water reducer with a water reduction rate of 25 to 40%, and the silane is selected from one or more of alkyl silane, amino silane, epoxy silane, and vinyl silane.

[0016] 1. This invention optimizes the physical properties and interfacial properties of coarse aggregate by subjecting it to grading and screening, high-pressure water washing, and immersion dust removal. This treatment process improves aggregate surface cleanliness and significantly enhances the mechanical and chemical bond strength between the coarse aggregate and the cementitious material, effectively increasing the strength of oil-absorbing, vegetation-rich, permeable concrete.

[0017] 2. The present invention effectively activates the surface properties of shell powder by subjecting it to gradient acid-base treatment. This treatment process first removes organic matter and carbonate impurities on the surface of the shell powder through alternating acid and alkali dissolution, exposing more active sites; then high-concentration alkali treatment hydroxylates the surface of the shell powder, significantly increasing its chemical reactivity with cementitious materials. The treated shell powder not only exerts a micro-aggregate filling effect in oil-absorbing and vegetation-based permeable concrete, but also participates in secondary hydration reactions to generate more CSH gel, thereby increasing the strength of the oil-absorbing and vegetation-based permeable concrete. At the same time, its unique microporous structure gives concrete excellent oil adsorption capacity.

[0018] 3. This invention uses a tabletop fluidity test to control the fluidity of the cementitious material within the range of 185-195 mm, ensuring the optimal performance of the oil-absorbing, plant-based, permeable concrete mixture. Within this fluidity range, the strength of the oil-absorbing, plant-based, permeable concrete is significantly improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 A flow chart of a method for preparing enhanced low-carbon oil-absorbing vegetation-based permeable concrete; Figure 2 The oil absorption diagram per unit mass of the sample in the method for preparing enhanced low-carbon oil-absorbing vegetation permeable concrete; Figure 3 A graph of oil absorption per unit volume of a sample in a method for preparing enhanced low-carbon oil-absorbing vegetation-based permeable concrete; Figure 4 This is a graph of the compressive strength of samples used in the method for preparing enhanced low-carbon oil-absorbing vegetation-based permeable concrete. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

[0021] A method for preparing enhanced low-carbon oil-absorbing and plant-based permeable concrete, comprising processing raw materials, determining the amount of a water-reducing agent in a cementitious material, and preparing the oil-absorbing and plant-based permeable concrete, such as Figure 1 As shown, the specific steps are: S1. First, use a vibrating screen with a vibration frequency of 20-30 Hz to classify the coarse aggregate and screen out coarse aggregate with a particle size of 5-10 mm. Then, use a high-pressure water gun with a pressure of ≥10 MPa to rinse the coarse aggregate. The water flow rate is controlled at 50-80 L / min and the continuous rinsing time is ≥5 min. Then, soak the coarse aggregate in water at room temperature for 6 h, during which time intermittent mechanical stirring is performed at a speed of 30 r / min. Finally, place the coarse aggregate in an oven set at a temperature of 110 ± 2 ℃ and dry it to constant weight. Then, use a vibrating screen again to obtain coarse aggregate with a particle size of 5-10 mm.

[0022] S2. First, wash the shells, put them in an oven with a set temperature of 80 ± 2 ℃ and dry them for 4 hours, then use a wall breaker to crush and sieve them to obtain shell powder with a particle size of 0.3~0.6 mm; then soak the shell powder in 30 wt% sodium citrate solution for 40~60 min, 18~25 wt% NaOH solution for 15~30 min, 5~12 wt% NaOH solution for 30~40 h, 20~30 wt% sodium citrate solution for 2~4 h, and 40~60 wt% NaOH solution for 20~30 h. After each soaking, wash with water until neutral, and finally use an industrial microwave oven to treat it at high temperature for 60 minutes to obtain modified shell powder.

[0023] Specifically, the shell is a scallop or a mussel, the NaOH solution is 95% analytically pure and solid NaOH particles, and the sodium citrate solution is 95% analytically pure and solid sodium citrate particles.

[0024] S3. Determine the amount of water reducer in concrete using a jump table fluidity test, specifically including the following sub-steps: S31. Determine the benchmark cementitious material under the optimal working condition of concrete: weigh cement, coarse aggregate and mixing water as raw materials by weight, where the mass ratio of coarse aggregate to cement is 3.7:1. Select five water-cement ratios of 0.30, 0.33, 0.35, 0.38 and 0.40 for trial mixing of permeable concrete, and evaluate the working condition of the mixture according to the CJJ / T135-2009 standard. When the water-cement ratio is 0.35, the mixture exhibits an optimal working condition of metallic luster, forms a ball when grasped by hand, and precipitates fine slurry. Therefore, the cementitious material system under this water-cement ratio is selected as the benchmark cementitious material.

[0025] S32. Determine the equivalent fluidity control range: The fluidity of the benchmark cementitious material obtained according to the GB / T2419-2020 standard test step S31 is 188.14 mm. Therefore, the equivalent fluidity control range is set to 185~195 mm as the benchmark target value for adjusting the water reducer dosage.

[0026] S33. According to relevant test data, in the range of 0.25-0.35, when the water-cement ratio is 0.30, the compressive strength of permeable concrete is the best. Therefore, the water reducer dosage is 0.5 parts by weight as the initial dosage, and then the water reducer is added in a gradient of 0.1 parts to conduct the fluidity matching test. The specific operation process is as follows: First, a certain weight of cement, fly ash, slag and modified shell powder were stirred at 140 r / min for 30 s in a cement mortar mixing pot to obtain a premixed liquid. Then, a mixture consisting of a water reducer and 70% mixing water was added and stirred at 140 r / min for 60 s. Then, a mixture consisting of silane and 30% mixing water was added after stirring at 285 r / min for 30 s. After standing for 90 s, a scraper was used to scrape the cementitious material on the mixer blades and the wall of the mixing pot to the center of the mixing pot within 15 s. Finally, after stirring at 285 r / min for 90 s, the cementitious material was obtained. If agglomeration occurred in the mixing pot, the mixing pot was stirred at 285 r / min for another 15 s.

[0027] Furthermore, during this step, to ensure the appropriate amount of water-reducing agent, the stirring speed of the mixing pot was varied within a range of ±5 r / min at 140 r / min and ±10 r / min at 285 r / min. Both the mixture of water-reducing agent and 70% mixing water and the mixture of silane and 30% mixing water were stirred in a magnetic stirrer for 30 seconds. If the measured fluidity did not reach the range of 185-195 mm, the water-reducing agent dosage was adjusted according to a gradient, and step S33 was repeated until the required fluidity was met.

[0028] At the same time, in order to reduce the need to dynamically adjust the water reducer dosage in the gradient test in step S33 and reduce the number of trial and error, a linear model of fluidity and water reducer dosage is established: Assuming that the fluidity (F) is linearly related to the water reducer dosage (C), the slope k and intercept b are obtained by fitting the test data: ; The slope k in the linear model of fluidity and water-reducing agent dosage is calculated by measuring the fluidity F1 and F2 of two tests with different water-reducing agent dosages (e.g., C1 = 0.5 phr and C2 = 0.6 phr). The expression is as follows: ; Where: F is the measured fluidity of the cementitious material, which is the core indicator for determining whether the water-reducing agent dosage is appropriate (target range 185-195 mm); C is the amount of water-reducing agent used (measured as a percentage of the total weight of the cementitious material or in parts by mass); for example, the initial dosage is 0.5 parts (i.e., 0.5%); k is the influence coefficient of the water-reducing agent dosage on fluidity, indicating the increase in fluidity in millimeters for each additional part of water-reducing agent; this is calculated by the difference in measured fluidity from the gradient test in step S33 (e.g., 0.5 parts → 0.6 parts → 0.7 parts); b is the intercept of the linear model, representing the theoretical fluidity of the cementitious material in the absence of water-reducing agent (C = 0); the fluidity of the baseline cementitious material (water-cement ratio 0.35) without water-reducing agent is 188.14 mm, but b here is a linear extrapolation value and may not be equal to 188.14 mm (requires calibration through testing).

[0029] If the measured fluidity F 实测 If the water reducing agent dosage exceeds the target range (185~195 mm), the target dosage (C 目标 ) can be calculated by the following formula: ; Where: F 目标 The target fluidity is 190 mm, which is the median value of the equivalent range of 185 to 195 mm, or fine-tuned according to actual needs. 实测 is the measured fluidity at the current water reducer dosage, C 当前is the dosage of water reducer in the current test (e.g. 0.5 parts initially).

[0030] S34. First, use a truncated cone mold to mold the cementitious material. The first layer is installed to 2 / 3 of the height of the truncated cone mold, and it is scored 5 times in each perpendicular direction and tamped 15 times from the edge to the center. The second layer is installed to 20 mm above the truncated cone mold, and it is scored 5 times in each perpendicular direction and tamped 10 times from the edge to the center. The excess cementitious material is scraped off and smoothed. Then, the truncated cone mold is lifted vertically upward, and the electric jumping table instrument is immediately started. It jumps 30 times within 30 s ± 1 s at a frequency of 1 time per second. After the jumping is completed, the diameters of the bottom surface of the cementitious material in two perpendicular directions are measured with a caliper, and the average value (mm) is calculated. The amount of water reducer is obtained when the equivalent fluidity control range of the cementitious material is 185~195 mm. At this time, the working state of the enhanced low-carbon oil-absorbing and plant-based permeable concrete is optimal.

[0031] S4. Add mixing water, coarse aggregate, fly ash, slag, cement, modified shell powder, a mixture of water reducer and mixing water, and a mixture of silane and mixing water to the mixer in sequence, and obtain enhanced low-carbon oil-absorbing and vegetation-bearing permeable concrete by staged mixing and layered mold filling and tamping. The specific operation process is as follows: S41. First, pour 30% of the mixing water and coarse aggregate into the mixer and stir for 60 seconds. Then, add a certain amount of fly ash, slag, cement and modified shell powder in sequence and stir for 90 seconds to obtain the intermediate premix.

[0032] S42. On the basis of step S41, a mixture consisting of the amount of water reducer determined in step S3 and 50% of mixing water is added and stirred for 60 seconds, and then a mixture consisting of silane and 20% of mixing water is added and stirred for 150 seconds to obtain a concrete mixture.

[0033] S43. The obtained concrete mixture was molded in three layers. A 2-cm-diameter round tamping rod was used to tamp each layer 25 times from the outside to the inside to ensure that the concrete was evenly compacted. The bottom of the mold was then tapped alternately 3 to 5 times to further compact the concrete. After the last layer was completed, the surface was leveled with a scraper. Finally, the molded specimens were covered with plastic film and placed in a curing box at 20 ± 2°C and 95% humidity for 72 h. After demolding, the specimens were cured to the design age.

[0034] The concrete obtained by the method for preparing enhanced low-carbon oil-absorbing and vegetation-based permeable concrete includes coarse aggregate, cement, fly ash, slag, modified shell powder, water reducer, silane and mixing water. The components by weight are: 1450-1550 parts of coarse aggregate, 140-450 parts of cement, 0-70 parts of fly ash, 0-15 parts of slag, 0-35 parts of modified shell powder, 0-5 parts of silane, 0-7 parts of water reducer, and 60-150 parts of mixing water.

[0035] Specifically, the components of the enhanced low-carbon, oil-absorbing, and vegetation-based permeable concrete are as follows: the coarse aggregate is granite crushed stone with a particle size of 5 to 10 mm; the modified shell powder is made by crushing shells, soaking in chemical solutions, and treating them at high temperatures; the water reducer is a polycarboxylic acid-based high-performance water reducer with a water reduction rate of 25 to 40%; the silane is selected from one or more of alkyl silane, amino silane, epoxy silane, and vinyl silane; the cement is P·Ⅱ 42.5 ordinary Portland cement; the fly ash is Class F Grade Ⅱ fly ash; and the slag is Grade S95 slag.

[0036] The following is a further description of a method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to the present invention in conjunction with an embodiment: The above method is used to process the coarse aggregate and shell powder in the raw materials. In this specific embodiment, the coarse aggregate is granite crushed stone, and the amount of water reducer in the cementitious material is determined to prepare oil-absorbing and vegetation-bearing permeable concrete.

[0037] Example 1: Granite crushed stone, cement, fly ash, slag, water reducing agent and mixing water are respectively 3 The mass (kg) is calculated as follows: 1496 parts of granite crushed stone, 149.5 parts of cement, 65.4 parts of fly ash, 9.3 parts of slag, 3.8 parts of water reducer and 89.7 parts of mixing water.

[0038] According to the above mixing ratio, the specific preparation steps are as follows: S41. First, pour 44.9 parts of mixing water and granite crushed stones into the mixer and stir for 60 seconds. Then, add fly ash, slag, cement and modified shell powder in sequence and stir for 90 seconds to obtain an intermediate premix.

[0039] S42. On the basis of step S41, a mixture consisting of 3.8 parts of a water reducing agent and 44.9 parts of mixing water is added and stirred for 210 seconds to obtain a permeable concrete mixture.

[0040] S43. The permeable concrete mixture was loaded into molds of 100 mm × 100 mm × 100 mm and 40 mm × 40 mm × 160 mm, coated with a release agent, in three layers. Each layer was tamped 25 times from the outside inward using a 2-cm diameter round tamping rod. The bottom of the mold was then tapped alternately 3–5 times left and right. After the last layer was completed, the surface was leveled with a scraper. Finally, the molded specimens were covered with plastic film and placed in a curing chamber at 20 ± 2°C and 95% humidity for 72 h before demolding. After demolding, the specimens were cured under the same conditions for 60 days to obtain Sample 1.

[0041] Example 2: Granite crushed stone, cement, fly ash, slag, modified shell powder, water reducing agent and water are respectively 3 The mass (kg) is calculated as follows: 1496 parts of granite crushed stone, 149.5 parts of cement, 65.4 parts of fly ash, 9.3 parts of slag, 29.9 parts of modified shell powder, 5.4 parts of water reducer and 89.7 parts of mixing water.

[0042] According to the above mix ratio, the specific preparation steps are as follows: S41. First, pour 44.9 parts of mixing water and granite crushed stones into the mixer and stir for 60 seconds. Then, add fly ash, slag, cement and modified shell powder in sequence and stir for 90 seconds to obtain an intermediate premix.

[0043] S42. On the basis of step S41, a mixture consisting of 5.4 parts of a water reducing agent and 44.9 parts of mixing water is added and stirred for 240 seconds to obtain a permeable concrete mixture.

[0044] S43. The permeable concrete mixture was loaded into molds of 100 mm × 100 mm × 100 mm and 40 mm × 40 mm × 160 mm, coated with a release agent, in three layers. Each layer was tamped 25 times from the outside inward using a 2-cm diameter round tamping rod. The bottom of the mold was then tapped alternately 3–5 times left and right. After the last layer was completed, the surface was leveled with a scraper. Finally, the molded specimens were covered with plastic film and placed in a curing chamber at 20 ± 2°C and 95% humidity for 72 h before demolding. After demolding, the specimens were cured under the same conditions for 60 days to obtain Sample 2.

[0045] Example 3: Granite crushed stone, cement, fly ash, slag, modified shell powder, water reducing agent, silane and mixing water are respectively 3 The mass (kg) is calculated as follows: 1496 parts of granite crushed stone, 149.5 parts of cement, 65.4 parts of fly ash, 9.3 parts of slag, 29.9 parts of modified shell powder, 3.1 parts of water reducer, 3.0 parts of silane and 89.7 parts of mixing water.

[0046] According to the above mix ratio, the specific preparation steps are as follows: S41. First, pour 26.9 parts of mixing water and granite crushed stone into the mixer and stir for 60 seconds. Then, add fly ash, slag, cement and modified shell powder in sequence and stir for 90 seconds to obtain an intermediate premix.

[0047] S42. On the basis of step S41, a mixture consisting of 3.1 parts of a water reducer and 44.9 parts of mixing water is added and stirred for 60 seconds, and then a mixture consisting of 17.9 parts of mixing water and silane is added and stirred for 150 seconds to obtain a permeable concrete mixture.

[0048] S43. The obtained permeable concrete mixture was loaded into molds of 100 mm × 100 mm × 100 mm and 40 mm × 40 mm × 160 mm, coated with a release agent, in three layers. Each layer was tamped 25 times from the outside to the inside using a 2 cm diameter round tamping rod. The bottom of the mold was then tapped alternately 3 to 5 times from left to right. After the last layer was completed, the surface was leveled with a scraper. Finally, the molded specimens were covered with plastic film and placed in a curing chamber at 20 ± 2°C and 95% humidity for 72 h before demolding. After demolding, the specimens were cured under the same conditions for 60 days to obtain Sample 3.

[0049] Comparative Example 1: Granite crushed stone, cement, water reducing agent and mixing water are respectively 3 The mass (kg) is calculated as: 1496 parts of granite crushed stone, 299.2 parts of cement, 0.3 parts of water reducer and 89.7 parts of mixing water.

[0050] According to the above mix ratio, the specific preparation steps are as follows: S41. First, pour 44.9 parts of mixing water and granite crushed stones into a mixer and stir for 60 seconds. Then add cement and stir for 90 seconds to obtain an intermediate premix.

[0051] S42. On the basis of step S41, a mixture consisting of 0.3 parts of a water reducing agent and 44.9 parts of mixing water is added and stirred for 210 seconds to obtain a permeable concrete mixture.

[0052] S43. The obtained permeable concrete mixture was loaded into molds of 100 mm × 100 mm × 100 mm and 40 mm × 40 mm × 160 mm, coated with a release agent, in three layers. Each layer was tamped 25 times from the outside to the inside using a 2 cm diameter round tamping rod. The bottom of the mold was then tapped alternately 3 to 5 times from left to right. After the last layer was completed, the surface was leveled with a scraper. Finally, the molded specimens were covered with plastic film and placed in a curing box at 20 ± 2°C and 95% humidity for 72 h before demolding. After demolding, the specimens were cured under the same conditions for 60 days to obtain comparative sample 1.

[0053] Comparative Example 2: Granite crushed stone, cement, water reducing agent and mixing water are respectively 3 The mass (kg) is calculated as follows: 1496 parts of 5-10 mm granite crushed stone, 400 parts of cement, 1.84 parts of water reducing agent and 100 parts of mixing water.

[0054] According to the above mix ratio, the specific preparation steps are as follows: S41. First, pour 60 parts of mixing water and granite crushed stones into a mixer and stir for 60 seconds. Then add cement and stir for 90 seconds to obtain an intermediate premix.

[0055] S42. On the basis of step S41, a mixture consisting of 1.84 parts of a water reducing agent and 60 parts of mixing water is added and stirred for 210 seconds to obtain a permeable concrete mixture.

[0056] S43. The obtained permeable concrete mixture was loaded into molds of 100 mm × 100 mm × 100 mm and 40 mm × 40 mm × 160 mm, coated with a release agent, in three layers. Each layer was tamped 25 times from the outside to the inside using a 2 cm diameter round tamping rod. The bottom of the mold was then tapped alternately 3 to 5 times from left to right. After the last layer was completed, the surface was leveled with a scraper. Finally, the molded specimens were covered with plastic film and placed in a curing box at 20 ± 2°C and 95% humidity for 72 h before demolding. After demolding, the specimens were cured under the same conditions for 60 days to obtain comparative sample 2.

[0057] Comparative Example 3: The difference from Comparative Example 2 is that the amount of mixing water is 112 parts, and the amount of water reducer is 1.20 parts, to obtain Comparative Sample 3.

[0058] Comparative Example 4: The difference from Comparative Example 2 is that the amount of mixing water is 120 parts, the amount of water reducer is 0.40 parts, and Comparative Sample 4 is obtained.

[0059] Comparative Example 5: The difference from Comparative Example 2 is that the amount of mixing water is 128 parts, the amount of water reducer is 0.20 parts, and Comparative Sample 5 is obtained.

[0060] Comparative Example 6: The difference from Comparative Example 2 is that the amount of mixing water is 140 parts, the amount of water reducer is 0 parts, and Comparative Sample 6 is obtained.

[0061] Comparative Example 7: The difference from Comparative Example 4 is that the amount of mixing water is 128.2 parts, and the amount of cement is 427.4 parts, to obtain Comparative Sample 7.

[0062] Comparative Example 8: The difference from Comparative Example 4 is that the amount of mixing water is 112.2 parts, and the amount of cement is 374.0 parts, to obtain Comparative Sample 8.

[0063] Comparative Example 9: The difference from Comparative Example 4 is that the amount of mixing water is 99.7 parts, and the amount of cement is 332.4 parts, to obtain Comparative Sample 9.

[0064] Comparative Example 10: The difference from Comparative Example 4 is that the amount of mixing water is 89.8 parts, and the amount of cement is 299.2 parts, to obtain Comparative Sample 10.

[0065] Comparative Example 11: The difference from Comparative Example 4 is that the amount of mixing water is 81.6 parts, and the amount of cement is 272.0 parts, to obtain Comparative Sample 11.

[0066] Comparative Example 12: The difference from Comparative Example 4 is that the amount of mixing water is 74.8 parts, and the amount of cement is 249.3 parts, to obtain Comparative Sample 12.

[0067] Comparative Example 13: The difference from Comparative Example 4 is that the amount of mixing water is 69.1 parts, and the amount of cement is 230.2 parts, to obtain Comparative Sample 13.

[0068] For Example and Comparative Example 1, specimens of two sizes were prepared: 100 mm × 100 mm × 100 mm and 40 mm × 40 mm × 160 mm. For Comparative Examples 2-13, specimens of 100 mm × 100 mm × 100 mm were prepared (Comparative Example 2 also included specimens of 40 mm × 40 mm × 160 mm). The compressive strength and porosity of the 100 mm × 100 mm × 100 mm cubic specimens were tested, while water and oil adsorption experiments were conducted on the 40 mm × 40 mm × 160 mm specimens.

[0069] The specific steps of the water-oil adsorption experiment are as follows: a. Place a 40 mm × 40 mm × 160 mm sample in an oven at 65°C until the daily mass loss rate drops to 0.1%. Remove the sample and cool it to room temperature. Measure its weight to the nearest 0.01 g. b. Weigh a certain amount of water and oil and place them in the test container so that when the sample is placed in the container along the long side, the liquid level is maintained at 1 / 2 of the test piece height. At the same time, the oil surface should be evenly distributed on the water surface.

[0070] c. Place the sample cooled to room temperature in a container filled with water-oil mixture and let it stand for 2 days.

[0071] d. Take the sample out of the container, wipe off the surface moisture, and measure its weight to the nearest 0.01 g.

[0072] e. Place the sample in an oven at 65°C until the daily mass loss rate drops to 0.1%. Record its weight to the nearest 0.01 g.

[0073] f. Arrange the data and calculate the oil absorption (g), oil absorption per unit mass (g / g) and oil absorption per unit volume (kg / m 3 ).

[0074] The results of the oil adsorption test are shown in Table 1: Table 1 Oil adsorption characteristics of cubic specimens Sample number Oil absorption per unit mass / (g / g) Oil absorption per unit volume / (kg / m3) Sample 1 0.0493 101.25 Sample 2 0.0577 112.58 Sample 3 0.0762 146.09 Comparative Sample 1 0.0347 69.80 The 60d compressive strength (MPa) of the cubic specimens was tested with reference to GB / T 50081-2019 “Standard for Test Methods of Physical and Mechanical Properties of Concrete”. The test results are shown in Table 2. Table 2 Compressive strength characteristics of samples Sample number Failure load (kN) Non-standard specimen strength (MPa) Standard specimen strength (MPa) Sample 1 142.2 14.2 13.51 Sample 2 172.6 17.3 16.40 Sample 3 166.8 16.7 15.85 Comparative Sample 1 205.4 20.5 19.51 Comparative Sample 2 169.5 16.9 16.1 Comparative Sample 3 190.5 19.1 18.1 Comparative Sample 4 211.6 21.2 20.1 Comparative sample 5 181.1 18.1 17.2 Comparative Sample 6 156.8 15.7 14.9 Comparative Sample 7 222.1 22.2 21.1 Comparative Sample 8 212.6 21.3 20.2 Comparative Sample 9 202.1 20.2 19.2 Comparative Sample 10 198.9 19.9 18.9 Comparative Sample 11 142.1 14.2 13.5 Comparative Sample 12 110.5 11.1 10.5 Comparative Sample 13 74.7 7.5 7.1 The porosity of the cubic specimens was tested with reference to T∕CSTM 00040-2019 “Test Methods for Permeable Concrete”. The test results are shown in Table 3. Table 3 Porosity characteristics of samples Sample number Effective porosity (%) Total porosity (%) Sample 1 23.14 25.22 Sample 2 22.19 24.36 Sample 3 21.82 23.51 Comparative Sample 1 21.36 23.13 Comparative Sample 2 18.72 21.18 Comparative Sample 3 17.15 20.76 Comparative Sample 4 17.27 21.97 Comparative sample 5 18.62 20.65 Comparative Sample 6 16.21 20.34 Comparative Sample 7 16.97 19.31 Comparative Sample 8 16.39 18.93 Comparative Sample 9 17.91 19.61 Comparative Sample 10 21.36 23.13 Comparative Sample 11 22.41 24.21 Comparative Sample 12 25.72 28.10 Comparative Sample 13 27.84 30.72 from Figure 2 and Figure 3 The oil absorption performance test results show that samples 1, 2, and 3 have significantly higher oil absorption per unit mass and per unit volume than sample 1. Sample 3 performed the best, with its oil absorption per unit mass increasing by 119.60% and its oil absorption per unit volume increasing by 109.30% compared to sample 1. This is mainly due to the synergistic effect of the modified shell powder and silane in the gelling system. The porous structure of the modified shell powder enhances adsorption capacity, while the surface modification effect of the silane optimizes the material's oil-water selectivity.

[0075] From Table 2 and Figure 4 The mechanical properties data show that Sample 2, by adding modified shell powder, achieved a 21.39% increase in compressive strength compared to Sample 1 without it. Sample 3, after adding silane to Sample 2, only experienced a 3.4% decrease in compressive strength. Sample 3 also had an effective porosity of 21.82% and a total porosity of 23.51%. Its basic performance indicators all met the requirements of the JC / T 2557-2020 "Botanical Concrete" specification of effective porosity ≥ 21% and total porosity ≤ 30%.

[0076] This invention utilizes the synergistic effect of modified shells and cementitious materials, combined with silane, to modify permeable concrete, significantly enhancing the material's oil absorption properties while maintaining mechanical properties. By optimizing the mix design, this preparation method not only improves material performance but also imparts excellent oil absorption capabilities to the permeable concrete, meeting the strength requirements for engineering applications.

[0077] The embodiments described above are merely descriptions of preferred implementations of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by ordinary technicians in this field should fall within the scope of protection determined by the claims of the present invention.

Claims

1. A method for preparing enhanced low-carbon oil-absorbing vegetation permeable concrete, characterized in that: The specific steps are: S1. First, the coarse aggregate is graded, then the coarse aggregate treated with a high-pressure water gun is soaked in water with intermittent stirring during the soaking period, and finally dried and again screened using a vibrating screen to obtain a coarse aggregate with a particle size of 5-10 mm; S2, first crushing and sieving the dried shells with a wall breaking machine to obtain shell powder with a particle size of 0.3-0.6 mm, then soaking them in sodium citrate solution and NaOH solution with different mass fractions, and finally treating them at high temperature to obtain modified shell powder; S3. First, determine the control range of the benchmark cementitious material and equivalent fluidity under the optimal working state of concrete; then, the water reducer is used as the initial dosage by weight, and then the water reducer is added in a gradient of 0.1 parts to perform a fluidity matching test. The specific process is: first, a certain weight of cement, fly ash, slag and modified shell powder are stirred at a speed of 140r / min for 30 seconds in a mixing pot to obtain a premixed liquid, then a mixture consisting of a water reducer and 70% mixing water is added and stirred at a speed of 140r / min for 60 seconds, then stirred at a speed of 285r / min for 30 seconds, and then a mixture consisting of silane and 30% mixing water is added. After standing for 90 seconds, the mixture is stirred at a speed of 285r / min for 90 seconds to obtain a cementitious material; finally, the gel material after mold installation is jumped using a jumping table instrument to obtain the amount of water reducer; S4. Add mixing water, coarse aggregate, fly ash, slag, cement, modified shell powder, a mixture of water reducer and mixing water, and a mixture of silane and mixing water into the mixer in sequence, and obtain enhanced low-carbon oil-absorbing and vegetation-based permeable concrete through staged mixing and layered mold filling and tamping.

2. The method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to claim 1, characterized in that: The specific process of preparing the enhanced low-carbon oil-absorbing vegetation permeable concrete in step S4 is as follows: S41. First, 30% of the mixing water and coarse aggregate were poured into a mixer and stirred for 60 seconds. Then, a certain amount of fly ash, slag, cement and modified shell powder were added in sequence and stirred for 90 seconds to obtain an intermediate premix. S42. On the basis of step S41, a mixture consisting of the amount of water reducer determined in step S3 and 50% of mixing water is added and stirred for 60 seconds, and then a mixture consisting of silane and 20% of mixing water is added and stirred for 150 seconds to obtain a concrete mixture; S43. The obtained concrete mixture is molded in three layers. For each layer, a 2-cm-diameter round tamping rod is used to tamp the mold from the outside to the inside 25 times, and the bottom of the mold is tapped alternately 3 to 5 times. After the last layer is completed, the surface is leveled with a scraper. Finally, the mixture is placed in a curing box at 20 ± 2°C and 95% humidity for 72 hours, and then demolded. After demolding, the mixture is cured to the design age.

3. The method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to claim 1, characterized in that: In step S3, if the fluidity F of the cementitious material measured in the test exceeds 185-195 mm, the amount of water reducer needs to be adjusted. The expression of the target amount Ctarget is as follows: ； Where: Ftarget is the target fluidity, which is taken as the median value of 190 mm in the equivalent range of 185-195 mm, or fine-tuned according to actual needs; Factual is the measured fluidity at the current water-reducing agent dosage; and Ccurrent is the water-reducing agent dosage in the current test.

4. The method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to claim 1 or 3, characterized in that: In step S3, the linear model of fluidity and water-reducing agent dosage is expressed as follows: ； Where: F is the measured fluidity of the cementitious material, C is the amount of water reducer, k is the influence coefficient of the water reducer dosage on fluidity, and b is the intercept of the linear model.

5. The method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to claim 1, characterized in that: In step S2, the NaOH solution is 95% analytically pure and contains solid NaOH particles, and the sodium citrate solution is 95% analytically pure and contains solid sodium citrate particles.

6. The method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to claim 1, characterized in that: In step S31, the stirring speed of the stirring pot is 140 r / min within a range of ± 5 r / min, and the stirring speed is 285 r / min within a range of ± 10 r / min.

7. The method for preparing enhanced low-carbon oil-absorbing vegetation-bearing permeable concrete according to claim 1, characterized in that: In step S31, a mixture of the water reducer and 70% of mixing water and a mixture of the silane and 30% of mixing water were both stirred by a magnetic stirrer for 30 seconds.

8. The method for preparing enhanced low-carbon oil-absorbing vegetation-permeable concrete according to claim 1, characterized in that: In step S31, after stirring at a speed of 285 r / min for 90 s, if agglomeration occurs in the stirring pot, the stirring pot is further stirred at a speed of 285 r / min for 15 s.

9. A concrete obtained by the method for preparing enhanced low-carbon oil-absorbing and vegetation-supported permeable concrete according to claims 1 to 8, characterized in that: It includes coarse aggregate, cement, fly ash, slag, modified shell powder, water reducer, silane and mixing water, and the components are respectively, by weight: 1450-1550 parts of coarse aggregate, 140-450 parts of cement, 0-70 parts of fly ash, 0-15 parts of slag, 0-35 parts of modified shell powder, 0-5 parts of silane, 0-7 parts of water reducer, and 60-150 parts of mixing water.

10. The concrete obtained by the method for preparing enhanced low-carbon oil-absorbing vegetation-bearing permeable concrete according to claim 9 is characterized in that: The coarse aggregate is granite gravel with a particle size of 5 to 10 mm, the shell is a scallop or a mussel, the water reducer is a polycarboxylic acid-based high-performance water reducer with a water reduction rate of 25 to 40%, and the silane is selected from one or more of alkyl silane, amino silane, epoxy silane, and vinyl silane.

Images