Modified recycled aggregate-based permeable pavement brick material, and preparation method and application thereof

Abstract

The present application relates to the technical field of building materials, in particular to a kind of water-permeable pavement brick material based on modified recycled aggregate and its preparation method and application.In the application, the advantages of volcanic rock-chitosan porous can load slow-release carbon source, mineralization precursor solution and auxiliary mineralization liquid inside volcanic rock-chitosan to obtain self-repairing filler;At the same time, the advantages of small particle size of volcanic rock-chitosan can load self-repairing filler inside recycled aggregate;With the exudation of desulfovibrio liquid, slow-release carbon source, mineralization precursor solution and auxiliary mineralization liquid, FeS is continuously and stably generated;FeS is induced to be generated by using the characteristics of desulfovibrio metabolism, which can not only fill the microcracks inside recycled aggregate, realize the modification of recycled aggregate defects and improve the filling hardness, but also can solidify heavy metal ions in road path flow pollutants.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a permeable paving brick material based on modified recycled aggregate, its preparation method, and its application. Background Technology

[0002] The information disclosed in this background section is intended only to enhance understanding of the overall background of the invention and is not necessarily to be construed as an admission or in any way implying that such information constitutes prior art known to those skilled in the art.

[0003] In cities, the combustion of large amounts of automotive fuel, oil leaks, tire wear, and the shedding of metal parts from car bodies generate significant amounts of heavy metal particles (including ions and fine solid particles) such as Pb, Cd, and Zn. These pollutants settle on road surfaces and are washed away by rainwater, flowing into rivers or seeping into groundwater, causing serious pollution of urban water sources. Some airborne particles enter the soil with rainwater and are absorbed by plants, harming not only plant life but also accumulating gradually in the food chain, thus endangering the health of other organisms in nature.

[0004] In recent years, there has been new development in the technology of using permeable cement-based materials for initial rainwater purification in urban roads after functional modification. Permeable road materials can not only quickly drain rainwater, prevent road surface water accumulation and replenish groundwater, but also adsorb heavy metals.

[0005] Furthermore, with the development of urbanization, the amount of construction waste generated has been increasing year by year, becoming another major challenge for environmental protection. Construction waste not only occupies land but also has a detrimental impact on the surrounding environment, sometimes even leading to urban sprawl. At the same time, with the continuous growth in the demand for sand and gravel aggregates in the construction industry, natural sand and gravel aggregate resources are becoming increasingly scarce, and the environmental damage caused by the indiscriminate mining of sand and gravel aggregates is becoming increasingly prominent. Therefore, it is of great significance to process construction waste into recycled aggregates for reuse in concrete production. Compared with natural aggregates, recycled aggregates made from construction waste have a large amount of old mortar adhering to their surface, resulting in defects such as high porosity, high water absorption, and high crushing index. This leads to a reduction in the performance of the recycled aggregate concrete, greatly limiting the application of recycled aggregates in practical engineering projects. Summary of the Invention

[0006] To overcome the above problems, this invention provides a permeable paving brick material based on modified recycled aggregate, its preparation method, and its application.

[0007] To achieve the above technical objectives, the present invention adopts the following technical solution: In a first aspect, the present invention provides a modified recycled aggregate, which is based on a silane coupling agent modified recycled aggregate and internally loaded with self-healing fillers. The self-healing filler uses a porous carrier as the matrix and is internally loaded with desulfurization Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization solution. The porous carrier is a volcanic rock-chitosan carrier; The slow-release carbon source is rapeseed stalk pellets; The mineralization precursor solution is a mixed aqueous solution of FeSO4 and CaCl2; The auxiliary mineralizing solution is a mixed aqueous solution of sodium salt and vitamins; The mass ratio of desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution, auxiliary mineralization solution and porous carrier is (35~40): (10~15): (25~30): (5~8): (10~12).

[0008] In one or more embodiments, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0009] In one or more embodiments, recycled aggregate includes one or more of recycled concrete aggregate and recycled clay brick aggregate.

[0010] Preferably, the recycled concrete aggregate has a particle size of less than 26.5 mm, a CaO content of >45%, a sum of SiO2 and Al2O3 content of >20%, and a porosity P that satisfies 15%≤P≤20%.

[0011] Preferably, the aggregate of recycled clay bricks has a particle size of less than 26.5 mm, a CaO content of >45%, a sum of SiO2 and Al2O3 content of >75%, and a porosity P that satisfies 25%≤P≤35%.

[0012] In one or more embodiments, the method for preparing silane coupling agent modified recycled aggregate includes: The surface of recycled aggregate is washed with water, dried, and then ultrasonically assisted cleaning is performed. After drying again, pretreated recycled aggregate is obtained. The pretreated recycled aggregate was soaked in a silane coupling agent solution, allowed to stand, and then dried to obtain silane coupling agent modified recycled aggregate.

[0013] Preferably, during ultrasonic-assisted cleaning, the ultrasonic power is 200~500 W; the cleaning time is 120~180 s.

[0014] Preferably, the silane coupling agent solution is a silane coupling agent ethanol solution, and the mass fraction of the silane coupling agent is 1-3%. Preferably, the settling time is 30 to 40 minutes.

[0015] In one or more embodiments, the specific surface area of ​​the volcanic rock-chitosan carrier is 80~120 m². 2 / g, bulk density is 300~500 kg / m³ 3 The particle size is 30~50 μm.

[0016] Preferably, the preparation method of the volcanic rock-chitosan carrier includes: After uniformly mixing powdered microporous volcanic rock, chitosan solution and epichlorohydrin crosslinking agent, the mixture is freeze-dried to obtain volcanic rock-chitosan carrier.

[0017] More preferably, the particle size of the powdered microporous volcanic rock is 2~50 nm; More preferably, the concentration of the chitosan solution is 1.5%~2.5% (w / v). More preferably, the mass ratio of powdered microporous volcanic rock, chitosan solution and epichlorohydrin crosslinking agent is (95~105):(15-25):(2-4).

[0018] In one or more embodiments, the OD value of the desulfurizing Vibrio bacterial solution is 1~1.2, and the bacterial cell concentration is 2×10⁻⁶. 9 ~2.4×10 9 CFU / mL.

[0019] Preferably, the method for preparing the desulfurization Vibrio bacterial solution includes: Desulfurized Vibrio was inoculated onto a culture medium and cultured to obtain a desulfurized Vibrio bacterial solution.

[0020] More preferably, the culture medium comprises 10-15 g / L sodium lactate, 1-5 g / L ammonium sulfate and 0.5-0.8 g / L potassium dihydrogen phosphate; and the pH is 8.5-9.5.

[0021] In one or more embodiments, the rapeseed stalk particles have a particle size of 50-100 μm.

[0022] In one or more embodiments, the mineralization precursor solution contains 7-10% FeSO4 and 4-8% CaCl2 by mass.

[0023] In one or more embodiments, the mixed sodium salt includes sodium lactate and sodium bicarbonate. Preferably, the concentration of sodium lactate is 1-3 g / L and the concentration of sodium bicarbonate is 8-12 g / L. Sodium lactate can supplement the carbon source, and sodium bicarbonate can adjust the alkalinity of the solution.

[0024] The vitamin is vitamin B12, preferably, the concentration of vitamin B12 is 0.1~0.3 mg / L.

[0025] The auxiliary mineralizing solution provides a suitable metabolic environment for desulfurization Vibrio.

[0026] A second aspect of the present invention provides a method for preparing the modified recycled aggregate described in the first aspect, comprising the following steps: (1) Mix the desulfurization Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization solution evenly, and load them into a porous carrier by vacuum impregnation to obtain self-healing filler; (2) The self-healing filler was loaded into the silane coupling agent modified recycled aggregate by vacuum impregnation to obtain the modified recycled aggregate precursor; (3) The modified recycled aggregate precursor is cured in a nitrogen atmosphere to obtain the modified recycled aggregate.

[0027] In one or more embodiments, in step (1), the mass ratio of desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution, auxiliary mineralization solution and porous carrier is (35~40):(10~15):(25~30):(5~8):(10~12).

[0028] In one or more embodiments, in step (1), during the vacuum impregnation process, the pressure is -0.12 to -0.08 MPa and the duration is 30 to 40 min.

[0029] In one or more embodiments, in step (2), the mass ratio of self-healing filler and silane coupling agent modified recycled aggregate is (95~105):(85~95).

[0030] In one or more embodiments, in step (2), during the vacuum impregnation process, the pressure is -0.12 to -0.08 MPa and the duration is 30 to 40 min.

[0031] In one or more embodiments, in step (3), maintenance includes initial maintenance and standard maintenance; During the initial maintenance process, the ambient temperature should be 35~40℃, the maintenance time should be 68~76 hours, and the humidity should be ≥90%.

[0032] During standard maintenance, the ambient temperature is 18~22℃, the humidity is ≥95%, and the maintenance time is ≥28 days.

[0033] A third aspect of the present invention provides a permeable paving brick material based on modified recycled aggregate, the raw materials of which include: The mixture consists of 18-28 parts solid waste cementitious material, 95-105 parts modified recycled aggregate, 5-9 parts water, and 0.3-0.6 parts water-reducing agent. The raw materials for solid waste cementitious materials include: 6-8 parts of carbide slag, 40-60 parts of mineral powder, 15-25 parts of rice husk ash, 5-10 parts of steel slag, and 10-20 parts of coal gasification slag.

[0034] In one or more embodiments, the Ca(OH)2 content in the carbide slag of the solid waste cementitious material is ≥80%; The ore powder is S95 grade or higher granulated blast furnace slag powder; Rice husk ash is the product of rice husks after controlled-temperature combustion at 500~700℃, with an amorphous SiO2 content of ≥85%. Steel slag pH ≥ 11; The moisture content of the coal gasification slag is ≤1%.

[0035] A fourth aspect of the present invention provides a method for preparing the permeable paving brick material based on modified recycled aggregate as described in the third aspect, comprising the following steps: According to the formula, carbide slag, mineral powder, rice husk ash, steel slag and coal gasification slag are mixed and then ball-milled to obtain solid waste cementitious material; After the solid waste cementitious material and modified recycled aggregate are mixed evenly, water and water-reducing agent are added, and the mixture is mixed evenly again to obtain the slurry; The slurry is added to a mold, pressed into shape, and cured to obtain a permeable paving brick material based on modified recycled aggregate.

[0036] In one or more embodiments, the specific surface area of ​​the ball-milled solid waste cementitious material is ≥400 m². 2 / kg.

[0037] In one or more embodiments, the maintenance includes high temperature and high humidity maintenance and standard maintenance; During the high temperature and high humidity curing process, the temperature is 55~65℃, the relative humidity is ≥90%, and the curing time is 40~48h. During standard curing, the temperature is 18~22℃, the humidity is ≥95%, and the curing time is 28 days.

[0038] A fifth aspect of the present invention provides the application of the permeable paving brick material based on modified recycled aggregate described in the third aspect or the permeable paving brick material based on modified recycled aggregate prepared by the preparation method described in the fourth aspect, wherein the permeable paving brick material based on modified recycled aggregate is laid on a road to purify road pollutants flowing through the permeable paving brick material based on modified recycled aggregate.

[0039] In one or more embodiments, the roadway pollutants include heavy metals, including lead (Pb), copper (Cu), and zinc (Zn).

[0040] The beneficial effects of this invention are as follows: (1) In this invention, the characteristics of desulfurization Vibrio metabolism are used to induce the generation of FeS, which can not only fill the microcracks inside the recycled aggregate, realize the defect modification of the recycled aggregate, and improve the filling hardness, but also solidify the heavy metal ions in the roadway pollutants.

[0041] Specifically, *Desulfovibrio* utilizes adenosine triphosphate (ATP) sulfatase, adenine-5'-phosphate sulfate (APS) reductase, and sulfite reductase to reduce sulfate ions to sulfides, which are then excreted from the cell. The extracellular HS... - S 2- Both can be supplied with external Fe 2+ The reaction generates FeS; the Mohs hardness of FeS is significantly higher than that of calcium carbonate produced by Bacillus pasteurellii metabolism, and this hardness advantage makes the filling layer of microcracks inside the recycled aggregate more robust. This invention utilizes the porous nature of volcanic rock-chitosan to load a slow-release carbon source, mineralization precursor solution, and auxiliary mineralization liquid within the volcanic rock-chitosan, obtaining a self-healing filler; simultaneously, it utilizes the small particle size advantage of volcanic rock-chitosan to load the self-healing filler within the recycled aggregate; with the seepage of desulfurizing Vibrio bacteria solution, slow-release carbon source, mineralization precursor solution, and auxiliary mineralization liquid, FeS is continuously and stably generated; the slow-release carbon source can slowly degrade and release small molecule organic matter, maintaining a stable carbon source concentration within the system, extending the metabolic cycle of desulfurizing Vibrio bacteria, and ensuring S 2- Continuous and uniform generation; mineralized precursor solution provides Fe 2+ The sulfate ions and the auxiliary mineralization solution provide a suitable metabolic environment for desulfurization Vibrio, ensuring the continuous growth and metabolism of desulfurization Vibrio.

[0042] In addition, the FeS generated by the metabolism of desulfurization Vibrio can react with heavy metals (including lead (Pb), copper (Cu) and zinc (Zn)) and convert them into insoluble compounds that are precipitated and adsorbed inside the recycled aggregate, thereby achieving the effect of solidifying heavy metal ions.

[0043] (2) The amino group (-NH2) in γ-aminopropyltriethoxysilane will react with S 2- It can form hydrogen bonds and act as Fe. 2+ The formation sites promote the directional growth of FeS in defects and cracks within recycled aggregates, ensuring that the generated FeS products are not easily detached.

[0044] (3) The desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization liquid are adsorbed into the porous carrier by vacuum impregnation to form a self-healing filler. The self-healing filler is also generally adsorbed into the recycled aggregate by vacuum impregnation, which can accurately repair the internal defects and cracks of the recycled aggregate. As the desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization liquid seep out, FeS is continuously and stably generated. FeS grows directionally in the internal defects and cracks of the recycled aggregate, which solves the problem that ordinary soaking modification cannot penetrate into the cracks.

[0045] (4) Permeable paving bricks based on modified recycled aggregates not only solidify heavy metal ions through FeS (the first line of defense), but also form a second line of defense through alkaline precipitation, physical adsorption, and geopolymer encapsulation generated by the solid waste cementitious material system. Specifically, in the strongly alkaline environment created by carbide slag and steel slag, heavy metal ions such as lead (Pb), copper (Cu), and zinc (Zn) will react with OH-. - The formation of insoluble hydroxide precipitates prevents the continued seepage of water-soluble heavy metal ions. Rice husk ash, coal gasification slag, and mineral powder in the system provide abundant porous structures and adsorption sites for physical adsorption, reducing the seepage of heavy metal ions through electrostatic adsorption and physical retention. Furthermore, during the polycondensation process, the calcium-silicon-aluminum geopolymer in the system can encapsulate heavy metal cations through lattice substitution, fixing them within the three-dimensional grid. A small portion of unencapsulated heavy metal cations are tightly wrapped by the geopolymer gel, preventing their dissolution and migration. Through the synergistic effect of the first and second lines of defense, the effect of solidifying heavy metal ions in permeable paving bricks based on modified recycled aggregates is significantly improved. Detailed Implementation

[0046] It should be noted that the following detailed descriptions are exemplary and intended to provide further illustration of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0047] It should be noted that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the scope of exemplary embodiments according to the invention. As used herein, the singular form is intended to include the plural form as well, unless the context clearly indicates otherwise. Furthermore, it should be understood that when the terms "comprising" and / or "including" are used in this specification, they indicate the presence of features, steps, operations, devices, components, and / or combinations thereof.

[0048] To enable those skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be described in detail below with reference to specific embodiments.

[0049] In the following examples, the rice husk ash is the product of rice husks after being burned at a controlled temperature of 600℃, and the amorphous SiO2 content is ≥90%.

[0050] Example 1 Preparation of modified recycled aggregate: (1) The surface of the mixture of recycled concrete aggregate and recycled clay brick aggregate was washed five times with water and dried at 80℃ for 24 h. Then, ultrasonic-assisted cleaning was performed with an ultrasonic power of 300 W and a cleaning time of 160 s. After that, it was dried at 80℃ for 12 h to obtain the pretreated recycled aggregate. In the mixture of recycled concrete aggregate and recycled clay brick aggregate, the mass ratio of recycled concrete aggregate to recycled clay brick aggregate was 60:40, and the particle size was less than 26.5 mm. The recycled concrete aggregate contained 48% CaO, 19% SiO2, 2% Al2O3, and 18% porosity P. The recycled clay brick aggregate contained 50% CaO, 62% SiO2, 19% Al2O3, and 28% porosity P.

[0051] The pretreated recycled aggregate was immersed in a 2% (w / w) γ-aminopropyltriethoxysilane ethanol solution, allowed to stand for 35 min, and dried at room temperature to obtain silane coupling agent modified recycled aggregate.

[0052] (2) Inoculate the desulfurized Vibrio onto the culture medium and culture until OD. 600 A value of 1 indicates the presence of *Vibrio desulfurans* culture. Culture medium composition: sodium lactate 12 g / L, ammonium sulfate 3 g / L, and potassium dihydrogen phosphate 0.6 g / L; pH 9.2.

[0053] 100 parts of powdered microporous volcanic rock, 20 parts of chitosan solution, and 3 parts of epichlorohydrin crosslinking agent were mixed evenly and then freeze-dried to obtain a volcanic rock-chitosan carrier. The microporous volcanic rock had a particle size of 35 nm, an average porosity of 55%, and a water absorption rate of 17%. The chitosan solution was a chitosan-acetic acid solution with a mass fraction of 2.2% w / v; the acetic acid concentration was 1.3% v / v; the chitosan molecular weight was 900 kDa; and the final particle size of the volcanic rock-chitosan carrier was 44 μm.

[0054] Thirty-eight parts of desulfurizing Vibrio bacterial solution, 12 parts of slow-release carbon source, 28 parts of mineralization precursor solution, 7 parts of auxiliary mineralization solution, and 12 parts of porous carrier were mixed evenly. The desulfurizing Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution, and auxiliary mineralization solution were loaded onto the porous carrier using a vacuum impregnation method to obtain a self-healing filler. During the vacuum impregnation process, the pressure was -0.10 MPa and the duration was 30 min. The slow-release carbon source was rapeseed straw particles with a particle size of 80 μm; the mineralization precursor solution was a mixed aqueous solution of FeSO4 and CaCl2, with FeSO4 having a mass fraction of 8% and CaCl2 a mass fraction of 5%; the auxiliary mineralization solution was a mixed aqueous solution of mixed sodium salt and vitamin; the mixed sodium salt consisted of sodium lactate and sodium bicarbonate, with sodium lactate having a concentration of 3 g / L and sodium bicarbonate having a concentration of 10 g / L; the vitamin was vitamin B12, with a concentration of 0.2 mg / L.

[0055] (3) 105 parts of self-healing filler were loaded into 95 parts of silane coupling agent modified recycled aggregate by vacuum impregnation to obtain modified recycled aggregate precursor; during the vacuum impregnation process, the pressure was -0.10 MPa and the duration was 30 min.

[0056] (4) The modified recycled aggregate precursor was placed in an initial anaerobic modification environment at an ambient temperature of 38°C for 72 hours; then it was placed in a standard environment at a temperature of 21°C and a relative humidity of 95% for 28 days to obtain the modified recycled aggregate.

[0057] Example 2 Compared with Example 1, the mass ratio of desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution, auxiliary mineralization liquid and porous carrier in step (2) is 35:11:26:7:11.

[0058] Example 3 Compared with Example 1, in step (2), the mass ratio of self-healing filler to silane coupling agent modified recycled aggregate is 95:95.

[0059] Comparative Example 1 Compared with Example 1, in step (1), the pretreated recycled aggregate is not modified with γ-aminopropyltriethoxysilane.

[0060] Comparative Example 2 Compared with Example 1, in step (2), no mineralization precursor solution is added to the self-healing filler.

[0061] Comparative Example 3 Compared with Example 1, in step (2), no auxiliary mineralizing liquid is added to the self-healing filler.

[0062] Comparative Example 4 Compared with Example 1, in step (2), the self-healing filler is prepared by a conventional impregnation method, that is, the porous carrier is dispersed in a mixture of desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization solution, and the impregnation time is 12 h.

[0063] Comparative Example 5 Compared to Example 1, in step (4), the modified recycled aggregate precursor is not cured. (The purpose of curing is to ensure that the desulfurization Vibrio has a better metabolic effect under suitable conditions, resulting in more FeS precipitation).

[0064] Comparative Example 6 Compared with Example 1, in step (2), the desulfurized Vibrio was replaced with a combination of Bacillus pasteurellii, Bacillus urealyticum, and Bacillus pumilus, with a ratio of 5:3:2. The corresponding culture medium was changed to 5.0 g / L peptone, 3.0 g / L beef extract, 20.0 g / L urea, 1.0 g / L distilled water, and pH 7.3.

[0065] Example 4 Preparation of permeable paving brick materials based on modified recycled aggregates: Eight parts of calcium carbide slag, 45 parts of mineral powder, 22 parts of rice husk ash, 8 parts of steel slag, and 13 parts of coal gasification slag were mixed and then ball-milled to obtain a solid waste cementitious material with a specific surface area of ​​420 m². 2 / kg; the ore powder is S105 ore powder; the pH of the steel slag is 13; the moisture content of the coal gasification slag is 0.4%.

[0066] After mixing 25 parts of solid waste cementitious material and 102 parts of modified recycled aggregate prepared in Example 1 evenly, 8 parts of water and 0.4 parts of water-reducing agent were added, and the mixture was mixed evenly again to obtain slurry. The slurry was added into a mold (200mm×100mm×60mm) and pressed into shape. The molding pressure was 10 MPa, the pressing speed was 0.4 MPa / min, and the static pressing time was 2 min. After demolding, the material was cured in an environment with a temperature of 62℃ and a relative humidity of 95% for 40 hours; then it was cured in a standard environment with a temperature of 22℃ and a relative humidity of 95% for 28 days to obtain permeable paving brick material based on modified recycled aggregate.

[0067] Example 5 Preparation of permeable paving brick materials based on modified recycled aggregates: A mixture of 7 parts calcium carbide slag, 47 parts mineral powder, 20 parts rice husk ash, 9 parts steel slag, and 16 parts coal gasification slag was ball-milled to obtain a solid waste cementitious material with a specific surface area of ​​420 m². 2 / kg; After mixing 27 parts of solid waste cementitious material and 99 parts of modified recycled aggregate prepared in Example 2 evenly, 7 parts of water and 0.5 parts of water-reducing agent were added, and the mixture was mixed evenly again to obtain slurry. The remaining steps are the same as in Example 4.

[0068] Example 6 Preparation of permeable paving brick materials based on modified recycled aggregates: Eight parts of calcium carbide slag, 46 parts of mineral powder, 22 parts of rice husk ash, 8 parts of steel slag, and 17 parts of coal gasification slag were mixed and then ball-milled to obtain a solid waste cementitious material with a specific surface area of ​​420 m². 2 / kg; After mixing 24 parts of solid waste cementitious material and 100 parts of modified recycled aggregate prepared in Example 3 evenly, 8 parts of water and 0.4 parts of water-reducing agent were added, and the mixture was mixed evenly again to obtain slurry. The remaining steps are the same as in Example 4.

[0069] Comparative Example 7 Compared with Example 4, the modified recycled aggregate prepared in Example 1 was replaced with the modified recycled aggregate prepared in Comparative Example 1, and the remaining steps were the same as in Example 4.

[0070] Comparative Example 8 Compared with Example 4, the modified recycled aggregate prepared in Example 1 was replaced with the modified recycled aggregate prepared in Comparative Example 2, and the remaining steps were the same as in Example 4.

[0071] Comparative Example 9 Compared with Example 4, the modified recycled aggregate prepared in Example 1 was replaced with the modified recycled aggregate prepared in Comparative Example 3, and the remaining steps were the same as in Example 4.

[0072] Comparative Example 10 Compared with Example 4, the modified recycled aggregate prepared in Example 1 was replaced with the modified recycled aggregate prepared in Comparative Example 4, and the remaining steps were the same as in Example 4.

[0073] Comparative Example 11 Compared with Example 4, the modified recycled aggregate prepared in Example 1 was replaced with the modified recycled aggregate prepared in Comparative Example 5, and the remaining steps were the same as in Example 4.

[0074] Comparative Example 12 Compared with Example 4, the modified recycled aggregate prepared in Example 1 was replaced with the modified recycled aggregate prepared in Comparative Example 6, and the remaining steps were the same as in Example 4.

[0075] Performance testing: (1) The permeable pavement brick materials prepared in Examples 4-6 and Comparative Examples 7-12 were tested for water absorption rate, crushing value and apparent density in accordance with JTG 3432-2024 "Specifications for Testing Aggregates in Highway Engineering". The results are shown in Table 1.

[0076] Table 1. Results of water absorption, crushing value and apparent density tests

[0077] Analysis of the test results of Examples 1-3 and the unmodified recycled aggregate shows that, compared with the unmodified recycled aggregate, the modified recycled aggregate in Examples 1-3 exhibits varying degrees of positive improvement in parameters such as water absorption, crushing value, and apparent density. The water absorption and crushing value can be reduced by up to 48.7% and 43.0%, respectively. This indicates that through the metabolism of desulfurizing Vibrio and the modification effect of the silane coupling agent, the self-healing filler generates and solidifies a large amount of FeS precipitate within the microcracks of the recycled aggregate. On the one hand, this repairs the microcracks and improves stress concentration; on the other hand, the FeS products fill the cracks, enabling them to bear external loads and reducing the crushing value of the recycled aggregate, thus playing a role in the overall modification of the recycled aggregate.

[0078] In Comparative Example 1, because the recycled aggregate was not modified with a silane coupling agent, the lack of adhesion effect from the silane coupling agent prevented the desulfurization Vibrio products in the open pores on the surface of the recycled aggregate from adhering tightly to the interior of the defects, resulting in poor performance. In Comparative Examples 2 and 3, because no mineralization precursor solution and auxiliary mineralization liquid were added to the self-healing filler, the metabolic process of desulfurization Vibrio was restricted, and a sufficient amount of FeS crystals were not formed to seal the microcracks, resulting in poor modification effect of the recycled aggregate. In Comparative Example 4, because only the conventional impregnation method was used, the self-healing filler could not fully penetrate into the interior of the microcracks, and only remained on the surface of the aggregate. FeS crystals were formed, but the internal stress concentration phenomenon was not significantly improved, resulting in high water absorption and crushing index. In Comparative Example 5, no initial anaerobic curing or standard curing was performed on the recycled aggregate. Although FeS minerals were formed, the mineralization directional deposition effect was poor and the secondary growth of mineral crystals was insufficient, making the performance of the recycled aggregate inferior to that of the examples. In Comparative Example 6, because the desulfurizing Vibrio was replaced with Bacillus pasteurellii, Bacillus urealyticum, and Bacillus pumilus, the main metabolic product was CaCO3, which had the effect of reducing water absorption and crushing value. However, because the Mohs hardness of CaCO3 is lower than that of FeS, the crushing value was slightly higher than that of Examples 1-3.

[0079] (2) The permeable paving brick materials prepared in Examples 4-6 and Comparative Examples 7-12 were tested for mechanical properties and permeability in accordance with GB / T 25993-2023 "Permeable Paving Bricks and Permeable Paving Brick Boards". The results are shown in Table 2.

[0080] The heavy metal ion adsorption capacity of the permeable pavement brick materials prepared in Examples 4-6 and Comparative Examples 7-12 was tested, and the method is as follows: Preparation of heavy metal ion solution: Prepare 1 L of aqueous solution containing lead (Pb), copper (Cu), and zinc (Zn) cations, wherein the ion concentrations of lead (Pb), copper (Cu), and zinc (Zn) are 75 mg / L, 35 mg / L, and 75 mg / L, respectively. Permeable paving bricks with dimensions of 200 mm × 100 mm × 60 mm were prepared according to the preparation methods in Examples 4-6 and Comparative Examples 7-12, with 3 bricks prepared for each example and comparative example. The permeable bricks were soaked in a heavy metal ion solution at a temperature of 25±2℃ for 60 days. During this period, the solution was shaken every 7 days, and deionized water was added to 1 L to eliminate the effect of water evaporation on ion concentration. The adsorption efficiency was calculated by measuring the change in the total content of heavy metal ions in the solution before and after soaking, and η was used as the adsorption efficiency of heavy metal ions in permeable pavement bricks.

[0081] .

[0082] Table 2 Test Results of Mechanical and Working Properties

[0083] In Examples 4-6, the modified recycled aggregates prepared in Examples 1-3 were used, resulting in a significant improvement in the performance of the permeable bricks made from the modified recycled aggregates compared to the unmodified recycled aggregates. With the permeability coefficient remaining essentially unchanged, the compressive strength increased from a maximum of 41 MPa to 66 MPa. This indicates that the positive modification by desulfurizing Vibrio generates a large amount of FeS precipitate within the microcracks of the recycled aggregates, repairing the microcracks and mitigating the stress concentration caused by them, thus improving the overall performance of the permeable pavement bricks. Meanwhile, the unmodified recycled aggregates themselves have almost no ion adsorption effect, while the adsorption effect of the permeable bricks in Examples 4-6 all reached over 30%.

[0084] In Comparative Examples 7-12, the adsorption efficiency of heavy metal ions decreased to varying degrees due to the use of modified recycled aggregates from Comparative Examples 1-6. In Comparative Example 7, no silane coupling agent modification was performed, and the FeS products did not adhere tightly to the microcracks within the recycled aggregate; only a small amount of the products possessed adsorption capacity. In Comparative Examples 8 and 9, the lack of mineralization precursors and auxiliary mineralization solutions resulted in reduced FeS product generation, preventing sufficient reaction with heavy metal ions. In Comparative Example 10, the lack of self-healing fillers within the recycled aggregate meant that only the FeS products on the aggregate surface possessed adsorption capacity. In Comparative Example 11, the absence of initial anaerobic modification and standard modification led to insufficient FeS product formation and deposition, resulting in a decrease in adsorption efficiency. In Comparative Example 12, the lack of desulfurization Vibrio bacteria meant that although CaCO3 precipitation was beneficial for improving the mechanical properties of permeable pavement bricks, it essentially lacked the ability to adsorb heavy metal ions, only solidifying them through alkaline precipitation, physical adsorption, and geopolymer encapsulation generated by the solid waste cementitious material system.

[0085] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A modified recycled aggregate, characterized in that, It uses recycled aggregate modified with silane coupling agent as the matrix and is internally loaded with self-healing filler; The self-healing filler uses a porous carrier as the matrix and is internally loaded with desulfurization Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization solution. The porous carrier is a volcanic rock-chitosan carrier; The slow-release carbon source is rapeseed stalk pellets; The mineralization precursor solution is a mixed aqueous solution of FeSO4 and CaCl2; The auxiliary mineralizing solution is a mixed aqueous solution of sodium salt and vitamins; The mass ratio of desulfurized Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution, auxiliary mineralization solution and porous carrier is (35~40): (10~15): (25~30): (5~8): (10~12).

2. The modified recycled aggregate as described in claim 1, characterized in that, The silane coupling agent is γ-aminopropyltriethoxysilane; Methods for preparing silane coupling agent modified recycled aggregates include: The surface of recycled aggregate is washed with water, dried, and then ultrasonically assisted cleaning is performed. After drying again, pretreated recycled aggregate is obtained. The pretreated recycled aggregate was soaked in a silane coupling agent solution, allowed to stand, and then dried to obtain silane coupling agent modified recycled aggregate. Recycled aggregates include one or more of recycled concrete aggregates and recycled clay brick aggregates.

3. The modified recycled aggregate as described in claim 1, characterized in that, The specific surface area of ​​the volcanic rock-chitosan carrier is 80~120 m². 2 / g, bulk density is 300~500 kg / m³ 3 ; The OD value of the desulfurizing Vibrio bacterial solution was 1~1.2, and the bacterial cell concentration was 2×10⁻⁶. 9 ~2.4×10 9 CFU / mL; The rapeseed stalk particles have a particle size of 50~100 μm; The mixed sodium salt comprises sodium lactate and sodium bicarbonate; the vitamin is vitamin B12.

4. The method for preparing the modified recycled aggregate according to any one of claims 1 to 3, characterized in that, Includes the following steps: (1) Mix the desulfurization Vibrio bacterial solution, slow-release carbon source, mineralization precursor solution and auxiliary mineralization solution evenly, and load them into a porous carrier by vacuum impregnation to obtain self-healing filler; (2) The self-healing filler was loaded into the silane coupling agent modified recycled aggregate by vacuum impregnation to obtain the modified recycled aggregate precursor; (3) The modified recycled aggregate precursor is cured in a nitrogen atmosphere to obtain the modified recycled aggregate.

5. The preparation method according to claim 4, characterized in that, In step (2), the mass ratio of self-healing filler to silane coupling agent modified recycled aggregate is (95~105):(85~95). In step (3), the maintenance includes initial maintenance and standard maintenance. During the initial maintenance, the ambient temperature is 35~40℃, the maintenance time is 68~76 h, and the humidity is ≥90%. During the standard maintenance, the ambient temperature is 18~22℃, the humidity is ≥95%, and the maintenance time is ≥28 days.

6. A permeable paving brick material based on modified recycled aggregate, characterized in that, Its raw materials include: The mixture consists of 18-28 parts solid waste cementitious material, 95-105 parts modified recycled aggregate, 5-9 parts water, and 0.3-0.6 parts water-reducing agent. The raw materials for solid waste cementitious materials include: 6-8 parts of calcium carbide slag, 40-60 parts of mineral powder, 15-25 parts of rice husk ash, 5-10 parts of steel slag, and 10-20 parts of coal gasification slag. The modified recycled aggregate is the modified recycled aggregate according to any one of claims 1 to 3 or the modified recycled aggregate prepared by the preparation method according to claim 4 or 5.

7. The method for preparing permeable paving brick material based on modified recycled aggregate as described in claim 6, characterized in that, Includes the following steps: According to the formula, carbide slag, mineral powder, rice husk ash, steel slag and coal gasification slag are mixed and then ball-milled to obtain solid waste cementitious material; After the solid waste cementitious material and modified recycled aggregate are mixed evenly, water and water-reducing agent are added, and the mixture is mixed evenly again to obtain the slurry. The slurry is added to a mold, pressed into shape, and cured to obtain a permeable paving brick material based on modified recycled aggregate.

8. The preparation method according to claim 7, characterized in that, The maintenance includes high-temperature and high-humidity maintenance and standard maintenance; During the high temperature and high humidity curing process, the temperature is 55~65℃, the relative humidity is ≥90%, and the curing time is 40~48 hours. During standard curing, the temperature is 18~22℃, the humidity is ≥95%, and the curing time is 28 days.

9. The application of the permeable paving brick material based on modified recycled aggregate as described in claim 6, or the permeable paving brick material based on modified recycled aggregate prepared by the preparation method described in claim 7 or 8, characterized in that, The permeable pavement brick material based on modified recycled aggregate is laid on the road to purify the road pollutants flowing through the permeable pavement brick material based on modified recycled aggregate.

10. The application as described in claim 9, characterized in that, Roadway pollutants include heavy metals, including lead, copper, and zinc.

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