Lightweight vegetation fine aggregate concrete and preparation method thereof

Abstract

The invention provides lightweight vegetation fine aggregate concrete and a preparation method thereof, and relates to the technical field of concrete. The lightweight vegetation fine aggregate concrete comprises the following components: sulphoaluminate cement, slag, diatomite, zeolite, vermiculite and water. According to the invention, the lightweight porous fine aggregate is adopted to replace conventional gravel, slag is doped to improve the matrix performance, diatomite and other functional components are added, the water-binder ratio is optimized, the hydration reaction process is controlled, and the like, so that a microporous structure with connectivity is introduced; the sulphoaluminate cement is adopted to replace conventional Portland cement so as to reduce the pH value of the concrete and shorten the maintenance time, and the prepared lightweight vegetation fine aggregate concrete is good in water permeability, has both the structure and the function and is beneficial to growth of green plants.

Description

Technical Field

[0001] The present invention relates to the technical field of concrete, and in particular to a lightweight vegetation fine aggregate concrete and a preparation method thereof. Background Art

[0002] In recent years, the field of indoor greening technology has seen significant progress in soilless cultivation, ecological green walls, and smart planting. However, conventional materials used in traditional planting products have exposed a series of performance limitations. While materials such as plastics, ceramics, and cement have some practicality in basic applications, their inherent properties cannot meet the needs of new planting systems. Plastics, while lightweight and economical, are too airtight, leading to root rot due to lack of oxygen, and their lack of surface porosity can easily breed algae. Ceramic products, while slightly permeable, have a high-density pore structure that limits water retention and requires frequent watering and maintenance. Furthermore, their brittle nature and process limitations make them difficult to meet the diverse demands of modern spatial design. Traditional cement-based materials, such as standard dense cement products, perform poorly in terms of air permeability and drainage. Alkaline precipitation can easily form salt crystals that damage plant roots, and they are also heavy. More critically, these traditional materials generally lack a nutrient-release mechanism, forcing plants to rely on external nutrient supply or require frequent substrate replacement, significantly increasing maintenance costs.

[0003] To address the performance shortcomings of these materials commonly used in traditional planting products, some research has attempted to introduce permeable concrete technology into the field of indoor greening and decoration. However, existing permeable concrete technology primarily serves municipal projects (such as sponge city pavements and permeable bricks), and its design objectives differ fundamentally from the specific needs of indoor greening products. While the porous structure created by adding coarse aggregate can improve permeability, the large aggregate particle size and high density result in a rough surface and poor pore connectivity, making it unable to meet the requirements for thin-walled and decorative flatness required for interior finishes.

[0004] Chinese patent application CN119080462A discloses a modified porous ecological concrete, comprising the following components: 180-220 parts of coarse aggregate, 45-55 parts of sulphoaluminate cement, 5-10 parts of modified diatomaceous earth, 4-8 parts of modified porous ceramsite, 5-10 parts of modified fiber, 2-4 parts of water reducer, 1-3 parts of retarder, and 20-40 parts of water. With coarse aggregate and sulphoaluminate cement as the main components, modified diatomaceous earth, modified porous ceramsite, modified fiber components, etc. are added to obtain a modified porous ecological concrete with high strength and low alkalinity. It is applied to slope protection projects, and the mechanical strength of concrete and the growth of planted grass are good. However, on the one hand, the porous structure formed by the coarse aggregate cannot meet the thin-wall and decorative flatness requirements of interior finishes. On the other hand, the complex and numerous components are not conducive to large-scale production.

[0005] Chinese patent application CN107935625A provides a low-alkalinity plant-growing type porous concrete, which comprises a porous concrete with a thickness and a mixed fine soil covering the surface layer of the porous concrete, and the raw materials of the porous concrete include the following components by volume density: cement 150-325 kg / m 3 , waste concrete recycled coarse aggregate 1495-1550 kg / m 3 , zeolite powder 20-30 kg / m 3 , fly ash 25-42 kg / m 3 , bentonite 10-15 kg / m 3 , silicon dioxide 15-20 kg / m 3 , fine soil 110-130 kg / m 3 , wood ash 2-3 kg / m 3 , rice husk charcoal 15-30 kg / m 3 , water reducing agent 2.5-4 kg / m 3 , EVA latex powder 15-22 kg / m 3 , butyl rubber powder 23-42 kg / m 3 , polyacrylate emulsion 19-26 kg / m 3 , organic compost 30-40 kg / m 3 , seaweed powder 3.5-4.5 kg / m 3 , vermiculite 10-20 kg / m 3 , tea dregs 0.8-1.0 kg / m 3 , neem cake 2-3 kg / m 3 , polyacrylamide 1.0-1.5 kg / m 3 , ferrous sulfate 0.5-1 kg / m 3 , modified loofah fiber 4-5 kg / m 3 , silicone defoaming agent 1.0-1.2 kg / m 3 , water 70-100 kg / m 3 However, the components are too many, which is not conducive to large-scale production.

[0006] Therefore, there is an urgent need to develop a new material that is breathable, water-retaining, and easy to make and process, to break through the material technology bottleneck in the field of indoor greening. SUMMARY

[0007] The present application aims at the above problems, and provides a lightweight vegetated fine aggregate concrete and a preparation method, wherein lightweight porous fine aggregate is used to replace conventional sand and gravel, slag is added to improve the matrix performance and utilize industrial solid waste, functional components such as diatomite are added, the water-binder ratio is optimized, and the hydration reaction process is controlled to introduce a connected microporous structure, and sulphoaluminate cement is used to replace conventional Portland cement to reduce the pH value of the concrete and shorten the curing time, so as to solve the above problems through the synergistic effect of material system reconstruction and process optimization.

[0008] To achieve the above object, the technical scheme adopted by the present application is as follows: In a first aspect, the present application provides a lightweight vegetated fine aggregate concrete, comprising the following components: sulphoaluminate cement, slag, diatomite, zeolite, vermiculite and water.

[0009] Preferably, the sulphoaluminate cement is grade 425 sulphoaluminate cement.

[0010] Preferably, the slag is grade S95 slag.

[0011] Preferably, the diatomite is 300-mesh white calcined diatomite.

[0012] Preferably, the zeolite is natural zeolite.

[0013] Further preferably, the particle size of the natural zeolite is 1-3 mm. More preferably, the particle size of the natural zeolite is 1-2 mm.

[0014] Preferably, the vermiculite is natural vermiculite that has not been expanded at high temperature.

[0015] Further preferably, the particle size of the natural vermiculite is 1-3 mm. More preferably, the particle size of the natural vermiculite is 1-2 mm.

[0016] Preferably, the mass ratio of the natural zeolite and the natural vermiculite is 1-2:1.

[0017] Preferably, the components include the following in terms of mass fraction: 200-280 parts of sulphoaluminate cement, 40-70 parts of slag, 10-20 parts of diatomite, 700-1100 parts of zeolite, 450-800 parts of vermiculite and 500-800 parts of water.

[0018] Further preferably, the components include the following in terms of mass fraction: 220-270 parts of sulphoaluminate cement, 40-60 parts of slag, 12-18 parts of diatomite, 700-1000 parts of zeolite, 500-800 parts of vermiculite and 550-650 parts of water.

[0019] More preferably, the components include, by mass fraction: 225-264 parts of sulphoaluminate cement, 45-60 parts of slag, 15-16.5 parts of diatomite, 750-1000 parts of zeolite, 500-750 parts of vermiculite and 570-605 parts of water.

[0020] In a second aspect, the present application provides a method for preparing the lightweight vegetated fine aggregate concrete as described above, comprising the following steps: S1: mixing sulphoaluminate cement, slag and diatomite to obtain a mixed powder; S2: mixing the mixed powder obtained in step S1, vermiculite, zeolite and water to obtain a concrete mixture; S3: forming the concrete mixture obtained in step S2 by vibration method to obtain a concrete; S4: curing the concrete obtained in step S3 for the first time, removing the mold, curing the second time, air-drying, and obtaining the final product.

[0021] Preferably, in step S1, the mixing is stirring, and the stirring time is 1-10 min; further preferably, the stirring time is 2-5 min.

[0022] Preferably, in step S1, the diatomite needs to be dried at 50-65℃ for 10-24h.

[0023] Preferably, in step S2, the vermiculite and zeolite need to be sieved first.

[0024] Preferably, in step S2, the specific operation of the mixing is: mixing zeolite, vermiculite and 70% of water for 30-90s, then pouring into the mixed powder and stirring for 20-40s, then adding the remaining 30% of water and stirring for 80-120s.

[0025] Preferably, in step S3, the vibration method is low-frequency vibration or manual vibration.

[0026] Preferably, in step S4, the temperature of the first curing is 15-25℃, the humidity is ≥93%, and the time is 10-16h; Further preferably, in step S4, the temperature of the first curing is 18-22℃, the humidity is ≥95%, and the time is 12-14h; Preferably, in step S4, the temperature of the second curing is 15-25℃, the humidity is ≥93%, and the time is 50-60h; Further preferably, in step S4, the temperature of the second curing is 18-22℃, the humidity is ≥95%, and the time is 55-60h; Preferably, in step S4, the temperature of the air-drying is 15-25℃, and the time is 22-24h.

[0027] Compared with the prior art, the present application has the following beneficial effects: (1) Outstanding environmental compatibility, the present application can reduce the PH value of concrete by adsorption of diatomite and selection of sulphoaluminate cement, adapt to the requirements of most ornamental plant root systems, and reduce the risk of alkaline damage; the substantial improvement of water permeability and water retention capacity can effectively avoid the problems of waterlogging and rapid dehydration.

[0028] (2) Integration of structure and function, the present application uses zeolite-vermiculite porous composite fine aggregate with a particle size of 1-2 mm, combines with slag to replace part of the cement to optimize the matrix and improve the late strength and durability, and cooperates with a twice feeding process to effectively reduce the density of concrete while ensuring a certain structural strength, and takes into account the requirements of thin-wall forming, delicate texture performance, water permeability and water retention efficiency, and load bearing.

[0029] (3) Equal emphasis on ecology and economy, the present application uses industrial by-products slag to replace part of the cement, which not only can reduce the material cost, but also can reduce the amount of high energy consumption cement; the use of sulphoaluminate cement can greatly shorten the curing time of concrete; the nutrient slow-release property of vermiculite-zeolite can reduce the frequency of artificial fertilization, and the replacement of organic water-retaining agent by diatomite can effectively reduce the cost; the preparation method is simple and easy to operate without the need for complex equipment, and is suitable for large-scale production. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 A comparison chart of water permeability test results of lightweight plant-growing fine aggregate concrete prepared for Example 1-Example 4 and Comparative Example 1-Comparative Example 4.

[0031] Figure 2 A comparison chart of water retention test results of lightweight plant-growing fine aggregate concrete prepared for Example 1-Example 4 and Comparative Example 1-Comparative Example 4.

[0032] Figure 3 A comparison chart of 7-day plant growth status of lightweight plant-growing fine aggregate concrete prepared for Example 1-Example 4 and Comparative Example 1-Comparative Example 4. DETAILED DESCRIPTION

[0033] In order to make the technical means, creative features, purposes and effects achieved by the present application easy to understand, the following specific embodiments are further described to illustrate the present application, but the following embodiments are only preferred embodiments of the present application, not all. Based on the embodiments in the embodiments, other embodiments obtained by those skilled in the art without creative labor are within the protection scope of the present application. It is worth noting that the raw materials used in the present application are ordinary commercially available products, and their sources are not specifically limited. The technologies and scientific terms used in the embodiments have the meanings generally understood by those skilled in the art to which the present application belongs.

[0034] Raw material purchase information or source: 425 grade sulphoaluminate cement meets the standard of GBT20472-2006; Diatomaceous earth is produced by Fengjie Diatomaceous Earth Co., Ltd. in Changbai Korean Autonomous County; S95 grade slag is produced by Weifang Huate Steel Plant; Zeolite is provided by Henan Tongde Environmental Protection Technology Co., Ltd., and vermiculite is provided by Lingshou County Hongyao Mineral Product Processing Factory.

[0035] Example 1 A lightweight vegetated fine aggregate concrete, raw materials of which are as follows in terms of weight parts: 240 parts of 425 grade sulphoaluminate cement, 15 parts of 300 mesh white calcined diatomaceous earth, 45 parts of S95 grade slag, 750 parts of natural zeolite with a particle size of 1-2 mm, 750 parts of unexpanded natural vermiculite sheet with a particle size of 1-2 mm, and 570 parts of water (mixing water).

[0036] Preparation method is as follows: S1. Aggregate pretreatment and powder mixing: natural zeolite and vermiculite are respectively sieved through a 1 mm standard sieve to remove broken materials and surface dust with a particle size less than 1 mm, so as to ensure that the aggregate particle size is uniformly distributed in the range of 1-2 mm; Sulphoaluminate cement, slag and diatomaceous earth are put into a high-shear powder mixer, and continuously stirred for 5 minutes until the powder is uniformly mixed.

[0037] S2. Two times of feeding and mixing: pretreated zeolite and vermiculite and 70% of mixing water are added to a forced mixer, and stirred at medium speed for 60 seconds to make the aggregate fully soaked. The whole powder mixture is poured into the mixer, and continues to be stirred for 30 seconds, then the remaining 30% of mixing water is slowly added, and the stirring speed is increased to high speed, and continues to be stirred for 90 seconds until the slurry uniformly wraps the aggregate.

[0038] S3. Molding and vibrating: the mixture is poured into a cylindrical mold with a diameter of φ114 mm, a height of 42 mm and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm, and slight vibration is carried out on a vibrating table, and the vibration time is strictly controlled within 10 seconds to remove air bubbles while retaining small pores.

[0039] S4. Curing treatment and drying treatment: the mold is transferred to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity≥95%), and after standing and curing for 12 hours, the mold is removed and continues to be cured for 60 hours.

[0040] Drying treatment: after the curing time is reached, the concrete casting is placed in a room (temperature 15-25℃) for natural air drying for 24 hours, and then it is obtained.

[0041] Example 2 A light-weight vegetated fine aggregate concrete, raw materials of which are as follows in parts by weight: 264 parts of 425-grade sulphoaluminate cement, 16.5 parts of 300-mesh white calcined diatomite, 49.5 parts of S95-grade slag, 750 parts of natural zeolite with a particle size of 1-2 mm, 750 parts of unexpanded natural mica sheet with a particle size of 1-2 mm, and 605 parts of water (mixing water).

[0042] The preparation method is as follows: S1. Aggregate pretreatment and powder mixing: the natural zeolite and the mica are respectively sieved through a 1 mm standard sieve to remove the broken materials and surface dust with a particle size less than 1 mm, so as to ensure that the aggregate particle size is uniformly distributed in the range of 1-2 mm; The sulphoaluminate cement, the slag, and the diatomite are put into a high-shear powder mixer, and continuously stirred for 10 minutes until the powder is uniformly mixed.

[0043] S2. Two-time feeding and mixing: the pretreated zeolite and mica and 70% of the mixing water are added into a forced mixer, and stirred at a medium speed for 30 seconds to fully soak the aggregate. The entire powder mixture is poured into the mixer, and continuously stirred for 40 seconds, and then the remaining 30% of the mixing water is slowly added, and the stirring speed is increased to a high speed, and continuously stirred for 120 seconds until the slurry uniformly covers the aggregate.

[0044] S3. Molding and vibrating: the mixture is poured into a cylindrical mold with a diameter of 114 mm, a height of 42 mm, and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm, and slightly vibrated on a vibrating table, and the vibrating time is strictly controlled within 10 seconds to remove the air bubbles while retaining the small pores.

[0045] S4. Curing treatment and drying treatment: the mold is transferred to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity≥95%), and left to stand for 14 hours after curing, and then demolded and continuously cured for 58 hours.

[0046] Drying treatment: after the curing time is reached, the concrete pouring piece is placed in a room (temperature 15-25℃) for natural air drying for 24 hours, and then obtained.

[0047] Example 3 A light-weight vegetated fine aggregate concrete, raw materials of which are as follows in parts by weight: 225 parts of 425-grade sulphoaluminate cement, 15 parts of 300-mesh white calcined diatomite, 60 parts of S95-grade slag, 750 parts of natural zeolite with a particle size of 1-2 mm, 750 parts of unexpanded natural mica sheet with a particle size of 1-2 mm, and 570 parts of water (mixing water).

[0048] The preparation method is as follows: S1. Aggregate pretreatment and powder mixing: Sieve the natural zeolite and vermiculite through a 1mm standard sieve to remove particles less than 1mm in size and surface powder, ensuring that the aggregate particle size is evenly distributed within the range of 1-2mm. Put sulphoaluminate cement, slag and diatomaceous earth into a high shear powder mixer and stir continuously for 10 minutes until the powders are evenly mixed.

[0049] S2. Double-feeding and mixing: Add the pretreated zeolite and vermiculite to a forced mixer along with 70% of the mixing water. Stir at medium speed for 90 seconds to fully saturate the aggregate. Pour the entire powder mixture into the mixer and continue stirring for 20 seconds. Then, slowly add the remaining 30% of the mixing water. Increase the stirring speed to high and continue stirring for 80 seconds until the slurry evenly coats the aggregate.

[0050] S3. Molding and Vibration: Pour the mixture into a cylindrical mold with a diameter of 114 mm, a height of 42 mm, and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm. Use a vibrating table to vibrate slightly. The vibration time is strictly controlled within 10 seconds to eliminate large bubbles while retaining tiny pores.

[0051] S4. Curing and drying: Transfer the mold to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity ≥95%), let it stand for 12 hours, then remove the mold and continue curing for another 60 hours.

[0052] Drying treatment: After the curing time is reached, place the concrete castings indoors (temperature is 15-25℃) and let them dry naturally for 22 hours.

[0053] Example 4 A lightweight plant-based fine aggregate concrete comprises the following raw materials, calculated by weight: 240 parts of 425-grade sulphoaluminate cement, 15 parts of 300-mesh white calcined diatomaceous earth, 45 parts of S95-grade slag, 1000 parts of natural zeolite with a particle size of 1-2 mm, 500 parts of unexpanded natural vermiculite flakes with a particle size of 1-2 mm, and 570 parts of water (mixing water).

[0054] The preparation method is consistent with that in Example 1.

[0055] Comparative Example 1 The invention discloses concrete, whose raw materials are as follows, calculated by weight: 500 parts of 425 grade Portland cement, 750 parts of natural river sand with a particle size of 1-2 mm, and 200 parts of water (mixing water).

[0056] The preparation method is: S1. Aggregate pretreatment: natural river sand is sieved through a 1mm standard sieve to remove particles less than 1mm in size and surface powder, ensuring that the aggregate particle size is evenly distributed within the range of 1-2mm; S2. Two-time feeding and mixing: the pretreated natural river sand and 70% of the mixing water were added into a forced mixer, and stirred at medium speed for 60 seconds to fully soak the aggregate. The 425-grade Portland cement was poured into the mixer, and the stirring was continued for 30 seconds, then the remaining 30% of the mixing water was slowly added, and the stirring speed was increased to high speed, and the stirring was continued for 90 seconds until the slurry uniformly wrapped the aggregate.

[0057] S3. Molding and vibrating: the mixture was poured into a cylindrical mold with a diameter of φ114 mm, a height of 42 mm, and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm, and was slightly vibrated using a vibrating table, and the vibrating time was strictly controlled within 10 seconds to eliminate air bubbles while retaining small pores.

[0058] S4. Curing and drying treatment: the mold was transferred to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity ≥95%), and was placed for 12 hours after demolding, and was continuously cured for a total curing time of 7 days.

[0059] Drying treatment: after the curing time, the concrete pouring piece was placed in a room (temperature 15-25℃) for natural air drying for 24 hours, and was obtained.

[0060] Comparative Example 2 A kind of concrete, the difference between Example 1 is that 425-grade Portland cement is replaced by 425-grade sulphoaluminate cement, and the raw materials are as follows in weight parts: 425-grade Portland cement 240 parts, 300 mesh white calcined diatomite 15 parts, S95 grade slag 45 parts, natural zeolite with particle size of 1-2 mm 750 parts, unexpanded natural vermiculite sheet with particle size of 1-2 mm 750 parts and water (mixing water) 570 parts.

[0061] The preparation method is the same as Example 1, and the total curing time needs to be extended to 7 days.

[0062] S1. Aggregate pretreatment and powder mixing: the natural zeolite and vermiculite were sieved through a 1 mm standard sieve respectively, and the broken materials and surface powder with particle size less than 1 mm were removed to ensure that the aggregate particle size was uniformly distributed in the range of 1-2 mm. The Portland cement, slag and diatomite were put into a high-shear powder mixer, and continuously stirred for 5 minutes until the powder was uniformly mixed.

[0063] S2. Two-time feeding and mixing: the pretreated zeolite and vermiculite and 70% of the mixing water were added into a forced mixer, and stirred at medium speed for 60 seconds to fully soak the aggregate. The entire powder mixture was poured into the mixer, and the stirring was continued for 30 seconds, then the remaining 30% of the mixing water was slowly added, and the stirring speed was increased to high speed, and the stirring was continued for 90 seconds until the slurry uniformly wrapped the aggregate.

[0064] S3. Molding and vibrating: The mixture was injected into a cylinder mold with a diameter of 114 mm, a height of 42 mm, and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm. Light vibration was performed using a vibrating table, and the vibration time was strictly controlled within 10 seconds to remove large bubbles while retaining small pores.

[0065] S4. Curing treatment and drying treatment: The mold was transferred to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity≥95%), and after 12h of static curing, the mold was removed and the curing was continued for a total of 7 days.

[0066] Drying treatment: After the curing period, the concrete casting was placed in a room (temperature 15-25℃) for natural air drying for 24h, and then obtained.

[0067] Comparative Example 3 A kind of concrete, by weight parts, the mixing ratio of this comparative example is: 425 grade sulphoaluminate cement 300 parts, natural zeolite with particle size of 1-2mm 750 parts, unexpanded natural sheet of vermiculite with particle size of 1-2mm 750 parts and water (mixing water) 440 parts.

[0068] The preparation method is as follows: S1. Aggregate pretreatment and powder mixing: The natural zeolite and vermiculite were sieved through a 1mm standard sieve, and the broken material and surface powder with a particle size less than 1mm were removed to ensure that the aggregate particle size was uniformly distributed in the range of 1-2mm. S2. Two-time feeding and mixing: The pretreated zeolite, vermiculite and 70% of the mixing water were added to a forced mixer, and stirred at medium speed for 60 seconds to fully soak the aggregate. The sulphoaluminate cement was poured into the mixer, and the stirring was continued for 30 seconds, then the remaining 30% of the mixing water was slowly added, and the stirring speed was increased to high speed for 90 seconds until the slurry uniformly wrapped the aggregate.

[0069] S3. Molding and vibrating: The mixture was injected into a cylinder mold with a diameter of 114 mm, a height of 42 mm, and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm. Light vibration was performed using a vibrating table, and the vibration time was strictly controlled within 10 seconds to remove large bubbles while retaining small pores.

[0070] S4. Curing treatment and drying treatment: The mold was transferred to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity≥95%), and after 12h of static curing, the mold was removed and the curing was continued for a total of 7 days.

[0071] Drying treatment: After the curing period, the concrete casting was placed in a room (temperature 15-25℃) for natural air drying for 24h, and then obtained.

[0072] Comparative Example 4 A light-weight vegetated fine aggregate concrete, which is different from Example 1 in that the natural zeolite and natural vermiculite are replaced by river sand with a particle size of 1-2 mm, and the raw materials are as follows in parts by weight: 240 parts of 425-grade sulphoaluminate cement, 15 parts of 300-mesh white calcined diatomite, 45 parts of S95-grade slag, 1500 parts of river sand with a particle size of 1-2 mm, and 300 parts of water (mixing water).

[0073] The preparation method is as follows: S1. Aggregate pretreatment and powder mixing: the river sand is sieved through a 1 mm standard sieve respectively, and the broken materials and surface dust with a particle size less than 1 mm are removed to ensure that the aggregate particle size is uniformly distributed in the range of 1-2 mm. The sulphoaluminate cement, slag and diatomite are put into a high-shear powder mixer, and continuously stirred for 5 minutes until the powder is uniformly mixed.

[0074] S2. Two-time feeding and mixing: the pretreated river sand and 70% of the mixing water are added to a forced mixer, and stirred at medium speed for 60 seconds to fully soak the aggregate. The entire powder mixture is poured into the mixer, and continues to be stirred for 30 seconds, then the remaining 30% of the mixing water is slowly added, and the stirring speed is increased to high speed, and continues to be stirred for 90 seconds until the slurry uniformly covers the aggregate.

[0075] S3. Molding and vibrating: the mixture is poured into a cylindrical mold with a diameter of φ114 mm, a height of 42 mm and a wall thickness of 5 mm, and a square plate mold with a side length of 120 mm and a thickness of 5 mm, and slight vibration is performed on a vibrating table, and the vibration time is strictly controlled within 10 seconds to remove air bubbles while retaining small pores.

[0076] S4. Curing treatment and drying treatment: the mold is transferred to a constant temperature and humidity curing room (temperature 20℃±2℃, relative humidity≥95%), and after standing and curing for 12 hours, the mold is removed and continues to be cured for 60 hours.

[0077] Drying treatment: after the curing time is reached, the concrete pouring piece is placed in a room (temperature 15-25℃) for natural air drying for 24 hours, and the product is obtained.

[0078] It is explained that Comparative Example 4 mainly investigates the influence of different aggregates on the formation and performance of concrete. Since most of the pervious concrete uses large-diameter sandstone as aggregate, the same type of small-diameter river sand is selected as a replacement aggregate, which can better reflect the advantages of the aggregate of the present application. However, the water absorption of river sand is much smaller than that of natural zeolite and natural vermiculite, so in order to form a concrete with the same appearance, the amount of mixing water is reduced.

[0079] Comparative Example 5 A lightweight vegetated fine aggregate concrete, which is different from example 1 in that the mass fractions of raw materials are different, and the raw materials are as follows in terms of weight fractions: 190 parts of 425-grade sulphoaluminate cement, 25 parts of 300-mesh white calcined diatomite, 80 parts of S95-grade slag, 575 parts of natural zeolite with a particle size of 1-2 mm, 650 parts of unexpanded natural mica sheet with a particle size of 1-2 mm, and 850 parts of water (mixing water).

[0080] The preparation method is the same as that of example 1.

[0081] The proportion cannot form concrete, and finally is in a layered state. Therefore, comparative example 5 is not subjected to subsequent tests.

[0082] Test example 1 Water permeability test A φ114 mm, 42 mm high, 5 mm thick cylindrical test piece is placed in a constant temperature oven at 105°C and dried to a constant weight, and the test piece can be taken out when the mass difference is less than 0.1% for two consecutive times. Pour 160 g of water into the cylindrical test piece, and place it in a closed plastic box. After 12 h and 24 h, respectively, weigh the amount of water seeped out of the test piece in the plastic box, and the results are shown in Tables 1 and Figure 1 .

[0083] Table 1. Water permeability test results

[0084] It can be seen that the water permeability of examples 1-4 is better than that of all comparative examples. Through comparative analysis, the role of each component can be determined: comparative example 1 and example 1 are compared, and the water permeability of the water permeable concrete prepared by the present application is much better than that of ordinary concrete; comparative example 2 and example 1 are compared, and only the type of cement is different, and the water permeability is poor, which shows that the sulphoaluminate cement system in the present application is more conducive to forming a stable porous structure. Comparative example 3 does not add slag and diatomite, and its water permeability is also not as good as that of the example, which shows that functional additives such as slag have a positive effect on optimizing the pore structure of the matrix and improving the water permeability. The aggregate used in comparative example 4 is ordinary river sand, and the result is far from the example because the water permeability of the aggregate itself is poor.

[0085] In addition, within the examples, the water permeability of example 3 (increasing the amount of slag) and example 4 (increasing the proportion of zeolite) is more prominent, which proves that within the proportioning range of the present application, appropriate adjustment of the content of slag and zeolite can further optimize the water permeability efficiency of the material.

[0086] Test example 2 Water retention test Cylindrical test pieces with a diameter of 114 mm, a height of 42 mm and a wall thickness of 5 mm were immersed in water for 24 h, removed, surface moisture was wiped off and the test pieces were weighed. The test pieces were left to stand in a thermostat at 25°C and weighed again after 12 h and 24 h. The water held by the test pieces was recorded and the results are shown in Table 2 and Figure 2

[0087] Table 2. Results of the water retention test

[0088] In terms of water retention (Table 2, Figure 2 ), the overall water retention of the examples is superior to all the comparative examples. In the examples, the late water retention of Example 3 and Example 4 is the most prominent, which shows that within the formulation range, increasing the slag content or adjusting the ratio of zeolite and vermiculite can further enhance the water retention and water holding capacity of the material under the premise of ensuring high water permeability, providing more persistent water supply for plants.

[0089] In addition, the weight of the test blocks prepared by the present application is significantly lower than that of conventional concrete test blocks. The weight of the test blocks of the examples is generally less than 200 grams, which is much lower than that of Comparative Example 1 (about 257 grams) and Comparative Example 4 (about 260 grams) using conventional river sand. This is mainly due to the use of porous lightweight fine aggregate such as zeolite and vermiculite in the formulation, which replaces the high-density conventional sand aggregate. The above significant weight reduction effect makes the material of the present application particularly suitable for indoor vertical greening and thin-walled decorative panels and other scenes with high load-bearing requirements, and has obvious application advantages.

[0090] Test Example 3 Plant growth test A 10x10 square grid with a basic unit of 10 mm was drawn on the surface of the poured concrete square piece with a side length of 120 mm and a thickness of 5 mm. In an environment with a temperature of 25±0.5°C and a humidity of about 50%, 1 part of chia seeds was stirred in 5 parts of water for 3 min and then left to stand for 30 min. After the gel was formed, it was evenly brushed on the concrete square piece and the germination state and average height were recorded by taking pictures, and the results are shown in Table 3. Figure 3

[0091] According to the plant growth test record photos Figure 3 ), by the 7th day, Examples 1-4 had the best growth, with tall and dense plants; Comparative Examples 3 and 4 had good growth but were slightly inferior to the example group (with an average plant height of about 1 cm); Comparative Example 2 grew slowly and sparsely; and the growth medium of Comparative Example 1 had completely dried out.

[0092] In summary, the test proves the feasibility of the concrete prepared according to the formulation of the present application as a partial hydroponic plant growth medium.

[0093] Test Example 4 pH value test ​​A cylinder specimen with a size of φ114mm, height 42mm, wall thickness 5mm was added with 160mL of deionized water and placed in a sealed clean disposable plastic container. It was kept at a constant temperature of (25±2)℃ for 24 hours. After the end of the standing period, the pH value of the soaking liquid was immediately measured using a calibrated pH meter, and the reading was recorded. The results are shown in Table 3.

[0094] Table 3. pH value test results

[0095] The pH value of the examples was between 8.40 and 8.60 (Table 3), which was overall weakly alkaline, meeting the growth requirements of most plants. The pH value of Comparative Example 1 (conventional concrete) and Comparative Example 2 (using Portland cement) was more than 11, which was strongly alkaline and was not conducive to plant growth.

[0096] This comparison strongly proves that the use of sulphoaluminate cement to replace traditional Portland cement is the core reason why the present application can significantly reduce the alkalinity of concrete and make it have excellent plant growth compatibility.

[0097] In summary, the present application successfully solves the water permeability-water retention contradiction, rough texture, alkaline corrosion and excessive self-weight of water permeable concrete in indoor plant growth applications through the design of innovative materials such as lightweight porous fine aggregate optimization, the selection of sulphoaluminate cement, diatomite and slag complex mixing, etc. The preparation method is controllable and has the potential for large-scale production, which can provide a high-performance material basis for indoor vertical greening and ecological decoration.

[0098] Finally, it should be noted that the above content is only used to illustrate the technical solutions of the present application, and is not a limitation on the protection scope of the present application. Simple modifications or equivalent replacements of the technical solutions of the present application made by those skilled in the art do not deviate from the essence and scope of the technical solutions of the present application.

Claims

1. A lightweight vegetation fine aggregate concrete, characterized in that: The composition includes the following: sulphoaluminate cement, slag, diatomaceous earth, zeolite, vermiculite and water.

2. The lightweight vegetation fine aggregate concrete according to claim 1, characterized in that: The sulphoaluminate cement is 425 grade sulphoaluminate cement; the slag is S95 grade slag; the diatomaceous earth is 300 mesh white calcined diatomaceous earth; the zeolite is natural zeolite; and the vermiculite is natural vermiculite that has not been expanded at high temperature.

3. The lightweight vegetation fine aggregate concrete according to claim 2, characterized in that: The particle size of the natural zeolite is 1-3 mm, and the particle size of the natural vermiculite is 1-3 mm; the mass ratio of the natural zeolite to the natural vermiculite is 1-2:

1.

4. The lightweight vegetation fine aggregate concrete according to claim 1, characterized in that: The invention comprises the following components in parts by mass: 200-280 parts of sulphoaluminate cement, 40-70 parts of slag, 10-20 parts of diatomaceous earth, 700-1100 parts of zeolite, 450-800 parts of vermiculite and 500-800 parts of water.

5. The lightweight vegetation fine aggregate concrete according to claim 4, characterized in that: The invention comprises the following components in parts by mass: 220-270 parts of sulphoaluminate cement, 40-60 parts of slag, 12-18 parts of diatomaceous earth, 700-1000 parts of zeolite, 500-800 parts of vermiculite and 550-650 parts of water.

6. The lightweight vegetation fine aggregate concrete according to claim 5, characterized in that: The invention comprises the following components in parts by mass: 225-264 parts of sulphoaluminate cement, 45-60 parts of slag, 15-16.5 parts of diatomaceous earth, 750-1000 parts of zeolite, 500-750 parts of vermiculite and 570-605 parts of water.

7. The method for preparing the lightweight vegetation fine aggregate concrete according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1: Sulphoaluminate cement, slag and diatomaceous earth are mixed to obtain a mixed powder; S2: mixing the mixed powder obtained in step S1, vermiculite, zeolite and water to obtain a concrete mixture; S3: Shaping the concrete mixture obtained in step S2 by vibrating to obtain concrete; S4: The concrete obtained in step S3 is subjected to primary curing, demoulding, secondary curing, and air drying.

8. The preparation method according to claim 7, characterized in that In step S1, the mixing is stirring, and the stirring time is 1-10 minutes.

9. The preparation method according to claim 7, characterized in that In step S2, the specific operation of the mixing is: mixing zeolite, vermiculite and 70% of water for 30-90 seconds, then pouring the mixed powder into the mixture and stirring for 20-40 seconds, and then adding the remaining 30% of water and stirring for another 80-120 seconds.

10. The preparation method according to claim 7, characterized in that In step S4, the temperature of the primary curing is 15-25°C, the humidity is ≥93%, and the time is 10-16 hours; the temperature of the secondary curing is 15-25°C, the humidity is ≥93%, and the time is 50-60 hours; the temperature of the air drying is 15-25°C, and the time is 22-24 hours.

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