Double-carrier self-repairing pervious concrete and preparation method thereof

Abstract

The invention relates to double-carrier self-repairing pervious concrete and a preparation method thereof, and belongs to the technical field of concrete, the double-carrier self-repairing pervious concrete comprises the following raw materials by weight: 1255-1455 parts of recycled aggregate, 90-110 parts of slag, 280-320 parts of cement, 29-39 parts of a water reducer, 1050-1150 parts of water, 80-100 parts of a microbial slow release body, and 150-180 parts of a nutrient slow release body. By adopting the microorganism slow-release body and the nutrient slow-release body, the problems of poor mechanical property and durability of the recycled aggregate pervious concrete caused by many micro cracks and poor firmness of the recycled aggregate are solved, the resource utilization of the construction waste and the real-time self-healing of the cracks are realized, and the application range of the pervious concrete is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, in particular to dual-carrier self-repairing permeable concrete and a preparation method thereof. Background Art

[0002] With the acceleration of urbanization in my country, the area of ​​hardened surface land has increased dramatically, leading to a significant decrease in rainwater infiltration capacity. Climate change has exacerbated the frequency of heavy rain, triggering a series of problems such as the "heat island effect," urban flooding, insufficient groundwater recharge, and traffic noise pollution. To alleviate these issues, the "sponge city" concept has emerged. Permeable concrete, due to its excellent porosity, has become a core material, requiring it to simultaneously provide drainage, water storage, and rainwater purification functions.

[0003] The booming construction industry is accompanied by a sharp increase in the amount of construction waste. The current recycling rate of construction waste is only 5%. Converting construction waste into recycled aggregates for use in permeable concrete can not only alleviate the consumption of natural resources, but also respond to the policy orientation of "zero-waste cities". In the existing technology, CN117645454B proposes a method for preparing permeable concrete using red brick recycled aggregate as raw material and molasses diluent; CN115010422B uses waste concrete and waste glass particles as aggregates to prepare recycled permeable concrete; CN115477489B improves the performance of recycled aggregates by modifying mud and sand; CN107226643B realizes 100% utilization of construction waste aggregates in concrete base / surface layers. The use of recycled aggregate permeable concrete not only alleviates the pressure on urban drainage systems, but also responds to the call for "zero-waste cities", saves natural resources, and protects the natural environment.

[0004] However, secondary crushing of recycled aggregates results in numerous microcracks, high crushing index, poor strength, and high heterogeneity. Furthermore, the aggregates are connected in a "point-to-point" manner, making recycled aggregate permeable concrete highly susceptible to failure under load. This significantly limits its use in cold regions. Therefore, there is an urgent need for a permeable concrete that combines the resource utilization of construction waste with high mechanical properties and long-term self-healing capabilities. Summary of the Invention

[0005] The purpose of the present invention is to provide dual-carrier self-repairing permeable concrete and its preparation method, which solves the problems of poor mechanical properties and durability of recycled aggregate permeable concrete due to the many microcracks, large crushing index, poor firmness and high heterogeneity of the recycled aggregate, while realizing the resource utilization of construction waste and expanding the scope of use of permeable concrete.

[0006] On the one hand, the dual-carrier self-repairing permeable concrete provided by the present invention adopts the following technical solutions: The dual-carrier self-repairing permeable concrete is characterized by comprising the following raw materials in parts by weight: 1255-1455 parts of recycled aggregate, 90-110 parts of slag, 280-320 parts of cement, 29-39 parts of water reducer, 1050-1150 parts of water, 80-100 parts of microbial slow-release body, and 150-180 parts of nutrient slow-release body.

[0007] Preferably, the microbial sustained-release agent comprises a microbial carrier and a microbial strain; The microbial carrier is made of recycled aggregate.

[0008] Preferably, the microbial sustained-release formulation comprises the following preparation steps: S1. Prepare a culture solution with a nitrogen source, a carbon source, sodium salt, calcium salt, potassium salt, and magnesium salt, and culture aerobic / anaerobic microorganisms in the culture solution at a constant temperature to obtain a microbial strain; S2. Place the microbial carrier in a vacuum impregnation pump, vacuum the microbial carrier until negative pressure is reached, adsorb the microbial strain obtained in step S1 into the vacuum impregnation pump through the pressure relief ball valve, close the pressure relief ball valve, adsorb for 10-15 minutes, close the vacuum impregnation pump, vibrate and disperse, and finally dry and spray the surface with protective liquid to obtain a microbial slow-release body.

[0009] Preferably, the protective solution in step S2 comprises potassium dihydrogen phosphate, magnesium oxide, anhydrous sodium acetate and water.

[0010] Preferably, the nutrient slow-release body comprises a nutrient solution and a nutrient carrier; The nutrient carrier is fiber.

[0011] Preferably, the nutrient sustained-release body comprises the following preparation steps: S1. Prepare a nutrient solution by taking peptone, sodium salt, potassium salt and magnesium salt; S2. Place the nutrient carrier in a vacuum impregnation pump, vacuum the nutrient carrier until negative pressure is reached, adsorb the nutrient solution prepared in step S1 into the vacuum impregnation pump through the pressure relief ball valve, close the pressure relief ball valve, adsorb for 10-15 minutes, close the vacuum impregnation pump, vibrate and disperse, and finally dry and spray the surface with protective liquid to obtain a microbial slow-release body.

[0012] Preferably, the water reducer is a polycarboxylic acid high-efficiency water reducer.

[0013] On the other hand, the present invention also provides a method for preparing the above-mentioned dual-carrier self-repairing permeable concrete, which adopts the following technical solution: The preparation method of dual-carrier self-repairing permeable concrete includes the following preparation steps: Add recycled aggregate, slag and cement into a mixer and pre-mix for 30-40 seconds, then add water reducer, water, microbial slow-release body and nutrient slow-release body, and stir for 180-200 seconds to obtain dual-carrier self-repairing permeable concrete.

[0014] In summary, the present invention has the following beneficial technical effects: 1. The present invention uses recycled aggregates to realize the resource utilization of construction waste, which meets the "low-carbon" requirements of today's society. The microbial slow-release body and nutrient slow-release body can achieve the function of repairing internal cracks in concrete multiple times.

[0015] 2. The nutrient carrier in the nutrient slow-release body of the present invention is hollow fiber with high porosity, which not only improves the mechanical properties of the original concrete structure but also provides space for the storage of nutrients.

[0016] 3. The present invention chooses to store microorganisms in microbial carriers to avoid storing nutrients in recycled aggregates, so as to prevent the low-strength recycled aggregates from cracking first, causing the nutrients to be released first and lose their activity due to lack of contact with microorganisms for a long time. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 The repair principle diagram of the dual-carrier self-repairing permeable concrete of the present invention; Figure 2 This is a flow chart for preparing the dual-carrier self-repairing permeable concrete of the present invention.

[0018] Explanation of the accompanying symbols: 1. fiber; 2. recycled aggregate; 3. concrete crack; 4. microbial slow-release body; 5. nutrient slow-release body; 6. repair trace. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solutions and advantages of this application more clear, the following further describes this application in detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0020] Preparation Example Preparation Example 1 The preparation method of the microbial sustained-release body comprises the following steps: 1) Prepare a culture solution with a nitrogen source, a carbon source, sodium salt, calcium salt, potassium salt, and magnesium salt, and culture aerobic / anaerobic microorganisms in the culture solution at a constant temperature to obtain a microbial strain; Among them, C source (3-3.5) g / L, N source (4-4.5) g / L, Na2CO3 (4.2-5) g / L, NaHCO3 (5.3-6) g / L, CaCl2 ( 0.1-0.15) g / L, KH2PO4 (0.02-0.4) g / L, KCl (0.45-0.5) g / L and MgSO4·7H2O (0.1-0.2) g / L; Bacillus coli and denitrifying microorganisms were used as aerobic and anaerobic microorganisms, respectively; 2) Using recycled aggregate as a microbial carrier and placing it in a vacuum impregnation pump, vacuuming the microbial carrier until negative pressure is reached, adsorbing the microbial strain prepared in step 1) into the vacuum impregnation pump through a pressure relief ball valve, then closing the pressure relief ball valve. After adsorption for 10-15 minutes, the vacuum impregnation pump is closed, vibrating and dispersing the microbial strain, and finally drying and spraying a protective liquid on the surface to obtain a microbial slow-release body; The protective solution includes 820 g / 1000 g of potassium dihydrogen phosphate, 2180 g / 1000 g of magnesium oxide, 43.6 g / 1000 g of anhydrous sodium acetate and 1350 g / 1000 g of water.

[0021] Preparation Example 2 The method for preparing a sustained-release nutrient body comprises the following steps: 1) Prepare nutrient solution with peptone, sodium salt, potassium salt and magnesium salt; Among them, peptone (5-7) g / L, Na2CO3 (4.2-5) g / L, NaHCO3 (5.3-6) g / L, KH2PO4 (0.02-0.4) g / L, KCl (0.45-0.5) g / L and MgSO4·7H2O (0.1- 0.2) g / L; 2) Using the fiber as a nutrient carrier and placing it in a vacuum impregnation pump, vacuuming the nutrient carrier until negative pressure is achieved, adsorbing the nutrient solution prepared in step 1) into the vacuum impregnation pump through a pressure relief ball valve, and then closing the pressure relief ball valve. After adsorption for 10-15 minutes, the vacuum impregnation pump is closed, vibrating and dispersing the fiber, and finally drying and spraying a protective liquid on the surface to seal the fiber, thereby preparing a nutrient slow-release body; The fiber is at least one of natural plant fiber (jute fiber, hemp fiber, sisal fiber, flax fiber), activated carbon fiber, meltblown fiber, foamed polymer fiber, ceramic fiber, alkali-resistant glass fiber, polyimide fiber, and graphene fiber; that is, the fiber in this embodiment is a fiber with high porosity; The protective solution includes 820 g / 1000 g of potassium dihydrogen phosphate, 2180 g / 1000 g of magnesium oxide, 43.6 g / 1000 g of anhydrous sodium acetate and 1350 g / 1000 g of water.

[0022] Example Example

[0023] Reference Figure 1 The preparation method of dual-carrier self-repairing permeable concrete comprises the following steps: 1300 parts of recycled aggregate, 94 parts of slag, and 290 parts of ordinary Portland cement (P.O42.5) were added to a mixer and premixed for 30-40 seconds. Finally, 30 parts of water reducer, 1080 parts of water, 86 parts of the microbial slow-release body prepared in Preparation Example 1, and 160 parts of the nutrient slow-release body prepared in Preparation Example 2 were added and stirred for 180-200 seconds to prepare dual-carrier self-repairing permeable concrete.

[0024] Example 2 Reference Figure 1 The preparation method of dual-carrier self-repairing permeable concrete comprises the following steps: 1255 parts of recycled aggregate, 90 parts of slag, and 280 parts of ordinary Portland cement (P.O42.5) were added to a mixer and premixed for 30-40 seconds. Finally, 29 parts of polycarboxylate high-efficiency water reducer, 1050 parts of water, 80 parts of the microbial slow-release body prepared in Preparation Example 1, and 150 parts of the nutrient slow-release body prepared in Preparation Example 2 were added and stirred for 180-200 seconds to prepare dual-carrier self-repairing permeable concrete.

[0025] Example 3 Reference Figure 1 The preparation method of dual-carrier self-repairing permeable concrete comprises the following steps: 1350 parts of recycled aggregate, 100 parts of slag, and 300 parts of ordinary Portland cement (P.O42.5) were added to a mixer and premixed for 30-40 seconds. Finally, 34 parts of polycarboxylate high-efficiency water reducer, 1100 parts of water, 90 parts of the microbial slow-release body prepared in Preparation Example 1, and 165 parts of the nutrient slow-release body prepared in Preparation Example 2 were added and stirred for 180-200 seconds to prepare dual-carrier self-repairing permeable concrete.

[0026] Example 4 Reference Figure 1 The preparation method of dual-carrier self-repairing permeable concrete comprises the following steps: 1400 parts of recycled aggregate, 105 parts of slag, and 310 parts of ordinary Portland cement (P.O42.5) were added to a mixer and premixed for 30-40 seconds. Finally, 35 parts of polycarboxylic acid high-efficiency water reducer, 1125 parts of water, 95 parts of the microbial slow-release body prepared in Preparation Example 1, and 172 parts of the nutrient slow-release body prepared in Preparation Example 2 were added and stirred for 180-200 seconds to prepare dual-carrier self-repairing permeable concrete.

[0027] Example 5 Reference Figure 1 The preparation method of dual-carrier self-repairing permeable concrete comprises the following steps: 1455 parts of recycled aggregate, 110 parts of slag, and 320 parts of ordinary Portland cement (P.O42.5) were added to a mixer and premixed for 30-40 seconds. Finally, 39 parts of polycarboxylate high-efficiency water reducer, 1150 parts of water, 100 parts of the microbial slow-release body prepared in Preparation Example 1, and 180 parts of the nutrient slow-release body prepared in Preparation Example 2 were added and stirred for 180-200 seconds to prepare dual-carrier self-repairing permeable concrete.

[0028] Comparative Example Comparative Example 1 The method for preparing permeable concrete is different from that in Example 2 in that the microbial carrier is replaced with an equal weight portion of recycled aggregate, and the remaining steps are the same as those in Example 2.

[0029] Comparative Example 2 The method for preparing permeable concrete is different from that in Example 2 in that the microbial carrier and the nutrient carrier are replaced with equal parts by weight of recycled aggregate, and finally 20 parts of fiber are added. The remaining steps are the same as those in Example 2.

[0030] Performance testing Test Method The dual-carrier self-repairing permeable concrete prepared in Examples 1-5 and Comparative Examples 1-2 was subjected to a water permeability coefficient performance test, a compressive strength test, and a frost resistance performance test.

[0031] According to the permeability test requirements of T / CSTM 00040-2019, "Test Methods for Permeable Concrete," concrete specimens prepared from Examples 1-5 and Comparative Examples 1-2 were used to make test specimens, and their permeability coefficients were tested. According to GB / T 50081-2019, "Standard for Testing Methods for Physical and Mechanical Properties of Concrete," concrete specimens prepared from Examples 1-5 and Comparative Examples 1-2 were used to make cubic specimens with a side length of 150 mm. The specimens were cured under standard conditions (temperature 20±3°C, relative humidity below 90%) for 28 days, and then subjected to compressive strength tests. According to Section 4.2 of "Test Methods for Long-term Properties and Durability of Ordinary Concrete" (Part 4 of the "Freeze-thaw Test," Section 4.2 of the "Quick Freezing Method"), concrete specimens prepared from Examples 1-5 and Comparative Examples 1-2 were used to make test specimens, and their freeze-thaw resistance was tested. The maximum number of freeze-thaw cycles at which the mass loss rate did not exceed 5% was used to determine the test results. The test results are shown in Table 1.

[0032] The test results are shown in Table 1.

[0033] Table 1 Performance test results of dual-carrier self-repairing permeable concrete Permeability coefficient / (mm / s) 28d compressive strength / MPa Freeze-thaw times / times Example 1 5.9 36.2 65 Example 2 6.3 38.6 60 Example 3 6.1 37.3 60 Example 4 5.9 36.3 55 Example 5 5.7 38.1 60 Comparative Example 1 5.1 25 25 Comparative Example 2 5.5 36.1 30 Reference Figure 2Combined with the test results in Table 1, it can be seen that the dual-carrier self-repairing permeable concrete includes recycled aggregate 2, microbial slow-release bodies 4, and nutrient slow-release bodies 5. The microbial slow-release bodies 4 and nutrient slow-release bodies 5 release microorganisms and nutrients into concrete cracks 3. After the action, the fibers 1 are mixed into the concrete. Furthermore, visible repair marks 6 are visible.

[0034] The water permeability coefficient of each embodiment is between 5.7-6.3mm / s, indicating that the permeable concrete has good water permeability, can meet the basic requirements for permeable materials in the construction of "sponge city", and can effectively realize drainage and water storage functions. The 28d compressive strength is between 36.2-38.6MPa, indicating that the permeable concrete has high mechanical strength. Compared with the traditional recycled aggregate permeable concrete, which has insufficient strength due to the performance defects of recycled aggregate, it has been significantly improved and can meet certain strength requirements for engineering applications. The number of freeze-thaw cycles reaches 55-65 times, which shows that the permeable concrete has good performance in anti-freeze-thaw, and to a certain extent solves the problem of low utilization rate of recycled aggregate permeable concrete in cold northern regions due to poor frost resistance, and expands its scope of use.

[0035] The above are all preferred embodiments of the present invention, and are not intended to limit the scope of protection of the present invention. Therefore, any equivalent changes made based on the structure, shape, and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. Dual-carrier self-repairing permeable concrete, characterized by: The invention comprises the following raw materials in parts by weight: 1255-1455 parts of recycled aggregate, 90-110 parts of slag, 280-320 parts of cement, 29-39 parts of water reducer, 1050-1150 parts of water, 80-100 parts of microbial slow-release body, and 150-180 parts of nutrient slow-release body.

2. The dual-carrier self-repairing permeable concrete according to claim 1, characterized in that: The microbial sustained-release body includes a microbial carrier and a microbial strain; The microbial carrier is made of recycled aggregate.

3. The dual-carrier self-repairing permeable concrete according to claim 2, characterized in that: The microbial slow-release formulation comprises the following preparation steps: S1. Prepare a culture solution with a nitrogen source, a carbon source, sodium salt, calcium salt, potassium salt, and magnesium salt, and culture aerobic / anaerobic microorganisms in the culture solution at a constant temperature to obtain a microbial strain; S2. Place the microbial carrier in a vacuum impregnation pump, vacuum the microbial carrier until negative pressure is reached, adsorb the microbial strain obtained in step S1 into the vacuum impregnation pump through the pressure relief ball valve, close the pressure relief ball valve, adsorb for 10-15 minutes, close the vacuum impregnation pump, vibrate and disperse, and finally dry and spray the surface with protective liquid to obtain a microbial slow-release body.

4. The dual-carrier self-repairing permeable concrete according to claim 3, characterized in that: The protective solution in step S2 includes potassium dihydrogen phosphate, magnesium oxide, anhydrous sodium acetate and water.

5. The dual-carrier self-repairing permeable concrete according to claim 4, characterized in that: The nutrient slow-release body includes a nutrient solution and a nutrient carrier; The nutrient carrier is fiber.

6. The dual-carrier self-repairing permeable concrete according to claim 5, characterized in that: The nutrient sustained-release body comprises the following preparation steps: S1. Prepare a nutrient solution by taking peptone, sodium salt, potassium salt and magnesium salt; S2. Place the nutrient carrier in a vacuum impregnation pump, vacuum the nutrient carrier until negative pressure is reached, adsorb the nutrient solution prepared in step S1 into the vacuum impregnation pump through the pressure relief ball valve, close the pressure relief ball valve, adsorb for 10-15 minutes, close the vacuum impregnation pump, vibrate and disperse, and finally dry and spray the surface with protective liquid to obtain a microbial slow-release body.

7. The dual-carrier self-repairing permeable concrete according to claim 1, characterized in that: The water reducer is a polycarboxylic acid high-efficiency water reducer.

8. A method for preparing the dual-carrier self-repairing permeable concrete according to any one of claims 1 to 7, characterized in that: The method comprises the following preparation steps: Add recycled aggregate, slag and cement into a mixer and pre-mix for 30-40 seconds, then add water reducer, water, microbial slow-release body and nutrient slow-release body, and stir for 180-200 seconds to obtain dual-carrier self-repairing permeable concrete.

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