Low-alkali, slow-release-fertilizer cementitious material for vegetation concrete and preparation method thereof

Abstract

The application discloses a low-alkali, slow-release-fertilizer cementitious material for vegetation concrete and a preparation method thereof. The cementitious material comprises 40-65 parts of slag sulphoaluminate cement, 3-30 parts of high belite sulphoaluminate cement clinker, 5-10 parts of modified sepiolite, 2-5 parts of phosphorus-containing waste, 1-5 parts of clay mineral and 2-12 parts of electrolytic manganese residue. The cementitious material has the characteristics of low pH value, low hydration heat, high early and late strength, can provide more effective internal curing material, improve the early crack resistance of concrete, reasonably and effectively adjust the pH value of the cementitious material by using solid waste material, has a wide pH value range, is beneficial to the germination and rooting of plant seeds, loads effective fertilizer and slowly releases the fertilizer effect, controls the storage and release of water, fertilizer ions or molecules, realizes the storage of water in the rainy season and the release in the dry season, the loading and storage of fertilizer ions or molecules in the topdressing period and the slow release in the later period.

Description

Technical Field

[0001] This invention relates to the field of cementitious materials for vegetation concrete, specifically to a low-alkali, slow-release fertilizer-effect cementitious material for vegetation concrete and its preparation method. Background Technology

[0002] With rapid economic development and the ever-changing urban landscape, the construction of numerous buildings, the dredging of rivers and ditches, and the creation of green and ecological environments in cities have led to the extensive use of impermeable concrete. This has exacerbated the urban heat island effect, significantly reduced the area of ​​green vegetation, and greatly increased the likelihood of urban flooding. Driven by the public's commitment to green living and energy conservation, there is a growing trend towards environmentally friendly, intelligent, and energy-efficient concrete. Porous concrete with environmental regulation capabilities is increasingly favored in municipal engineering projects. It combines the functional properties of concrete with ecological requirements, offering high permeability to allow for rapid drainage of large amounts of rainwater, while also possessing sufficient strength to withstand pressure and being compatible with plants and animals.

[0003] Vegetated concrete is a type of concrete in which green vegetation is planted on a porous concrete base. It is composed of low-alkalinity cementitious materials and a continuous porous aggregate skeleton, and has a network of interconnected pores similar to permeable concrete. It can improve the porosity, air permeability, water permeability and load-bearing capacity of concrete, while allowing natural rainwater to infiltrate back into the ground. The huge interconnected pores inside the vegetated concrete can provide sufficient space for plant root growth, and the nutrient matrix covering the concrete can provide the necessary nutrients for root development.

[0004] Currently, most vegetated concrete uses ordinary silicate cement as the base cementitious material. During the hydration process of silicate cement, a large amount of Ca(OH)2 is produced, filling the voids with a large amount of alkaline solution, resulting in an alkalinity pH value as high as 12.5-13.5. This is detrimental to plant growth. Even when low-alkalinity sulfoaluminate cement is chosen, its alkalinity pH value is mostly maintained within the range of 10.0-12.0. Plant growth substrates have certain requirements for pH; the pH of common ornamental grass growth substrates is in the range of 5-9. Excessively high alkalinity pH values ​​are not conducive to plant germination and growth. Therefore, vegetated concrete still requires the use of external alkalinity-reducing agents to lower the alkalinity.

[0005] Invention patent CN 109824333 B discloses a low-alkali, enhanced cementitious material for vegetation concrete and its preparation method. The invention discloses the use of 60-90 parts α-hemihydrate gypsum, 10-30 parts metakaolin, and 1-2 parts additives; the additives are composed of citric acid and polycarboxylate superplasticizer. The α-hemihydrate gypsum is generated from natural dihydrate gypsum in a saturated steam autoclave environment at 1.1-1.4 atmospheres and 120-145℃. The metakaolin is obtained by calcining kaolin at 700℃-800℃ for 2-6 hours to dehydrate it, forming a metastable, highly active admixture. This cementitious material solves the problem of excessively high alkalinity in vegetation concrete and can also obtain vegetation concrete with high strength, high durability, and good vegetation performance. However, the material is mainly composed of calcium sulfate and highly active metakaolin. However, the components do not contain an alkaline calcium source, so they cannot undergo hydration and cementation reactions, nor can they form hydration products such as ettringite that provide strength. The prepared cementitious material has low early strength. Although the cementitious material has a low alkalinity pH value, it cannot provide the necessary strength for vegetation concrete.

[0006] Invention patent CN 115321925 A discloses a cementitious material for vegetated concrete. This invention comprises 5-15 parts of low-alkali sulfur-aluminum cement, 1-2 parts of low-heat cement, 4-6 parts of phosphogypsum, 0.5-1 part of superphosphate, 0.08-0.15 parts of heavy calcium carbonate powder, and 2-4 parts of bentonite. The cementitious material for vegetated concrete provided by this invention has low carbon emissions, low native pH, and requires less buffer; it has simple curing conditions and saves on maintenance costs; the resulting vegetated concrete, when used for slope restoration in mines or roads, has a high seed germination rate and good slope protection effect; furthermore, it can carbonize and absorb carbon dioxide and heavy metal ions and fluorides from the surrounding soil, making it environmentally friendly. However, the low-alkali sulfur-alumina cement and low-heat cement proposed in this invention patent are commercially available and mature cement systems. Although the alkalinity pH value of low-alkali cement is low, at 10.0-10.5, the alkalinity pH value of low-heat cement is 12-13. In the process of selecting basic materials, the alkalinity pH value is too high, which is not conducive to plant growth. In addition, the content of industrial waste phosphogypsum, superphosphate, heavy calcium carbonate powder, and bentonite is too high, and the composition is too complex.

[0007] Invention patent CN 107548949 A discloses a low-alkalinity cementitious material for vegetated concrete and its preparation method. The composition and mass fractions of each component are as follows: 60-100 parts ultrafine slag powder; 20-30 parts silicate cement; 0-20 parts modified component; 5-20 parts waste mortar powder; 0.05-0.5 parts waste rubber particles; 0-1 parts expanded perlite powder; and 0.1-2 parts water-reducing agent. This invention first adds the water-reducing agent, modified component, waste mortar powder, and expanded perlite powder to silicate cement and mixes them evenly. Then, it mixes with waste rubber particles and ultrafine slag powder to prepare the low-alkalinity cementitious material. This invention can fully utilize industrial waste, realizing the resource utilization of waste, and is beneficial to the later performance of the cementitious material. By effectively reducing the pH value of the system, it provides good growth conditions for plants, which is beneficial to improving the overall performance of vegetated permeable concrete. However, this invention's cementitious material suffers from problems such as low early strength and slow later strength growth.

[0008] Invention patent CN201410175215.7 discloses a fertilizer-effective slow-release steel slag aggregate suitable for planted concrete and its preparation method. The invention includes the following processing steps: (1) sieving the selected iron steel slag, taking particles with a particle size between 19 and 26 mm, washing them with high-pressure water, and air-drying them naturally; (2) taking particles with a specific surface area of ​​300 to 400 m² 2 / Kg of powdered fertilizer is mixed with steel slag particles until the fertilizer powder fills the pores of the steel slag particles; (3) the treated steel slag particles are soaked in a uniform slurry made of 40-65% cement, 10-30% slag and 16-30% water (mass percentage) for 10 seconds and then taken out and air-dried to obtain fertilizer-slow-release steel slag aggregate. The steel slag aggregate provided by this invention carries its own nutrient components and can be slowly released during service, improving the fertilizer retention of planted concrete; turning industrial waste steel slag into treasure, reducing the environmental and social burden; the raw materials are readily available and the process is simple. However, the method of high-pressure washing and mixing with fertilizer in this invention has a limited amount of fertilizer that can be loaded by steel slag and the slow-release effect is not ideal. Summary of the Invention

[0009] To address the shortcomings of current technologies, this invention provides a low-alkali, slow-release fertilizer-enhancing cementitious material for vegetation concrete. This material has a low alkalinity (pH value), low heat of hydration, and high early and late strength. It can effectively utilize solid waste materials and adjust the pH value of the cementitious material, providing a wide pH range that is beneficial for plant seed germination and root development, loading effective fertilizers, and slowly releasing fertilizer effects.

[0010] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0011] A low-alkali, slow-release fertilizer-effect vegetation concrete binder, comprising the following raw materials in parts by weight:

[0012]

[0013] Furthermore, the modified sepiolite is prepared using the following steps: [The steps involve] preparing sepiolite with a specific surface area of ​​250-300 m² / g. 2 / kg of sepiolite was pre-ground to a specific surface area of ​​350±20m². 2 / kg, acidified with sulfuric acid solution and then ground to a specific surface area of ​​450±50m² 2 / kg, and finally the pH value was adjusted to 6.9-7.2 with Ca(OH)2, and after drying, modified sepiolite was obtained.

[0014] Furthermore, the concentration of the sulfuric acid solution is 1-5 mol / mL, the effective content of Ca(OH)2 is 85-95 wt.%, the rotation speed of pre-grinding and grinding is 60-100 r / min, the grinding time is 20-60 s, and a zirconia planetary ball mill is used for pre-grinding and grinding.

[0015] Furthermore, the phosphorus-containing waste is phosphate slag or modified phosphogypsum.

[0016] Furthermore, after calcining the modified phosphogypsum at 300℃ for 30 minutes, the effective water-soluble phosphorus and eutectic phosphorus content of the modified phosphogypsum before modification is ≥1.0 wt.%; the effective water-soluble phosphorus content of the phosphate slag is ≥0.8 wt.%.

[0017] Furthermore, the specific surface area of ​​clay minerals is 380-450 m². 2 / kg, the clay minerals are any one or two of montmorillonite, illite, attapulgite, chlorite, and metakaolinite.

[0018] Furthermore, the heat of hydration of slag sulfoaluminate cement is ≤150 J / g at 3d and ≤200 J / g at 7d, and its specific surface area is 430±20 m². 2 / kg.

[0019] Furthermore, the dicalcium silicate content of the high-belite sulfur-aluminate cement clinker is not less than 40 wt.%, and the 3-day compressive strength is ≥42.5 MPa and the 28-day compressive strength is ≥52.5 MPa.

[0020] Furthermore, the electrolytic manganese slag has a pH value of 6.0-7.2, a SiO2 content of 33-50 wt.%, and an Al2O3 content of 14-30 wt.%.

[0021] This invention also provides a method for preparing a low-alkali, fertilizer-slow-release cementitious material for vegetation concrete, comprising the following steps:

[0022] Step 1: Weigh 40-65 parts of slag sulfoaluminate cement and 3-30 parts of high belite sulfoaluminate cement clinker and mix for 5-10 minutes to obtain cementitious strength material A.

[0023] Step 2: Weigh 5-10 parts of modified sepiolite, 2-5 parts of phosphorus-containing waste, 1-5 parts of clay minerals, and 2-12 parts of electrolytic manganese slag, mix for 10-15 minutes, and then place at 250-300℃ for high-temperature mixing for 2-2.5 hours to obtain supplementary modified material B.

[0024] Step 3: Mix the cementitious strength material A and the supplementary modifier B for 30-40 minutes to obtain the low-alkali, fertilizer-effect slow-release cementitious material for vegetation concrete.

[0025] Preferably, a V-type mixer is used for mixing in steps 1 and 3;

[0026] Preferably, a roller high-temperature furnace is used for mixing in step 2, and the high-temperature mixing speed is 50 r / min.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] 1. The low-alkali, slow-release fertilizer-effect cementitious material of the present invention has a low alkalinity pH value (generally below 8.0). In the subsequent preparation of vegetation concrete (permeable concrete), there is no need to add alkali-reducing agent, and there is no need to add other mineral admixtures to the concrete, which simplifies the concrete preparation process.

[0029] 2. The low-alkali, fertilizer-efficiency slow-release vegetation concrete cementitious material of the present invention uses a low-alkali, early-strength, and high-strength cementitious material as its base cementitious material, which has excellent resistance to sulfate attack. Its low-alkali performance fundamentally reduces the alkalinity of the vegetation concrete.

[0030] 3. Due to the presence of many impurities in the primary minerals of sepiolite, some carbonate impurities can easily cause blockage when present in the zeolite water channels. In addition, the presence of a network structure centered on Mg ore makes the internal channels of sepiolite even more difficult to open. This not only reduces the theoretical specific surface area of ​​sepiolite, but also affects its moisture absorption and release properties.

[0031] This invention employs a step-by-step modification process to obtain modified sepiolite, increasing its porosity and specific surface area, thus enhancing its selective hygroscopicity. Due to stronger surface chemical adsorption and a denser capillary effect, water adsorbed by the modified sepiolite is less prone to desorption. The easily desorbed water originates from surface physical adsorption. Therefore, the desorption rate of the modified sepiolite is lower than its absorption rate, resulting in a more significant internal protective effect compared to the raw ore.

[0032] This invention employs a combined physical and chemical method to modify sepiolite. For sepiolite with a low specific surface area that is easily dispersed into fibers, dispersion is performed first. Then, for sepiolite with larger particles that are difficult to grind, acid treatment is used. This step-by-step modification method can modify sepiolite components into particles that have both partial fibers and, after acid modification, a large specific surface area with active cavities. Furthermore, these active cavities can carry water molecules and a large number of manganese ions, phosphate ions, phosphorus ions, etc., intelligently regulating the release of fertilizer molecules and ions throughout the entire life cycle of vegetated concrete based on the concentration of mineral ions, and also playing a role in water retention and slow-release fertilizer effects in vegetated concrete.

[0033] 4. Sepiolite does not expand in volume after absorbing a large amount of water, and the modified sepiolite becomes softer after absorbing water, but hardens again once the water is released and it dries. This effectively solves the problem of poor dispersibility of highly absorbent resins and water-absorbing porous materials in conventional internal curing concrete, as well as the reduction of cement stone strength due to water release. During the modification process of sepiolite, a large number of hydrophilic Si-OH groups exist on the surface of the modified sepiolite crystals, and Mg groups are present at the edges of the modified sepiolite crystals. 2+ Coordinated water readily reacts with polar H2O to form covalent bonds, and under acidic conditions, it can load more manganese ions, sulfate ions, ammonium ions, phosphate ions and other ions. Furthermore, modified sepiolite has a more stable structure under alkaline conditions, which can enhance the toughness of cement stone and improve its flexural strength.

[0034] 5. This invention uses weakly acidic electrolytic manganese slag as a supplementary cementing material. Electrolytic manganese slag is the waste residue from electrolytic treatment in the electrolytic manganese industry. It is primarily weakly acidic, which can alleviate the alkalinity (pH value) of the main cementing material to a certain extent. The large amount of ammonium ions, manganese ions, and sulfate ions contained in the electrolytic manganese slag can be loaded into the zeolite water channels of porous sepiolite and can replace Mg... 2+ In the later stages of construction, it can better release ions into the environment that have a certain fertilizing effect to improve vegetation, effectively ensuring the germination of plant seeds and the subsequent short-term supply of phosphorus and nitrogen fertilizers; and for soils with low manganese content and neutral or alkaline pH, it provides effective manganese ions to promote the germination and maturation of plant seeds, while increasing the utilization rate of phosphorus and calcium elements by plants, and can slowly release fertilizer groups and ions, which is beneficial to plant growth.

[0035] 6. This invention uses phosphate slag or modified phosphogypsum as a component of the cementitious material to provide the necessary phosphorus element for plant growth. It also combines with slag sulfoaluminate cement to form an interwoven network structure of acicular ettringite, enhancing early flexural strength and providing favorable space for CSH gelation, thus promoting the later hydration process. The modified phosphogypsum is calcined at high temperature to form dehydrated phosphogypsum, which, when combined with slag sulfoaluminate cement, activates the slag, increasing its hydration activity and improving the early and later mortar strength of the cementitious material. Furthermore, the higher amorphous mineral content of the phosphate slag also enhances the strength of the cementitious material. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0037] The slag sulfoaluminate cement used in this invention is commercially available slag sulfoaluminate cement.

[0038] Example 1

[0039] As a preferred embodiment of the present invention, this embodiment uses a low-alkali, fertilizer-effective slow-release cementitious material for vegetation concrete, the specific composition of which is shown in Table 1:

[0040] Table 1

[0041]

[0042]

[0043] In this embodiment, the heat of hydration of slag sulfoaluminate cement is 140 J / g at 3d and 192 J / g at 7d, and the specific surface area is 430 m². 2 / kg, 3d compressive strength = 38.5MPa, 28d compressive strength = 55.0MPa.

[0044] In this embodiment, the dicalcium silicate content of the high belite sulfur-aluminate cement clinker is 42.0 wt.%, the 3-day compressive strength is 43.5 MPa, and the 28-day compressive strength is 58.2 MPa.

[0045] In this embodiment, the specific surface area of ​​the clay mineral is 400 m². 2 / kg, the clay minerals are metakaolin and montmorillonite, the mass ratio of metakaolin to montmorillonite is 1:3, and the montmorillonite is montmorillonite powder.

[0046] In this embodiment, the electrolytic manganese slag has a pH value of 6.5, a SiO2 content of 33 wt.%, and an Al2O3 content of 18 wt.%.

[0047] In this embodiment, the modified sepiolite was prepared using the following steps: a specific surface area of ​​300 m² was used to prepare the sepiolite. 2 / kg of sepiolite was pre-ground in a zirconia planetary ball mill at a speed of 100 r / min to a specific surface area of ​​358.1 m². 2 / kg, acidified with 1mol / mL sulfuric acid solution for 30s, then ground to a specific surface area of ​​420m². 2 / kg, and finally the pH value was adjusted to 7.1 with Ca(OH)2 with an effective content of 89wt.%, and after drying, modified sepiolite was obtained.

[0048] In this embodiment, the phosphorus-containing waste is modified phosphogypsum. The effective water-soluble phosphorus and eutectic phosphorus content of the phosphogypsum before modification is 1.0 wt.%.

[0049] Weigh 60 parts of slag sulfoaluminate cement and 3 parts of high belite sulfoaluminate cement clinker and mix them in a V-type mixer for 5 minutes to obtain cementitious strength material A1.

[0050] Weigh 5 parts of modified sepiolite, 2 parts of modified phosphogypsum, 1 part of clay minerals and 5 parts of electrolytic manganese slag and mix them in a V-type mixer for 10 minutes. Then place them at 250℃ and mix them at a speed of 50 r / min for 2 hours to obtain supplementary modified material B1.

[0051] The cementitious strength material A1 and the supplementary modification material B1 were mixed for 30 minutes to obtain the low-alkali, fertilizer-effect slow-release cementitious material for vegetation concrete in this embodiment, which is denoted as #1.

[0052] Example 2

[0053] As a preferred embodiment of the present invention, this embodiment uses a low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material, the specific composition of which is shown in Table 2:

[0054] Table 2

[0055] Slag sulfoaluminate cement 50 High belite sulfur-aluminate cement clinker 30 Modified sepiolite 10 Modified phosphogypsum 2 Clay minerals (mass ratio of attapulgite to metakaolin = 1:2) 5 Electrolytic manganese slag 8

[0056] In this embodiment, the heat of hydration of slag sulfoaluminate cement is 128 J / g at 3d and 178 J / g at 7d, and the specific surface area is 440 m². 2 / kg, 3d compressive strength = 35.5MPa, 28d compressive strength = 55.0MPa.

[0057] In this embodiment, the dicalcium silicate content of the high belite sulfur-aluminate cement clinker is 46.0 wt.%, the 3-day compressive strength is 42.5 MPa, and the 28-day compressive strength is 57.2 MPa.

[0058] In this embodiment, the specific surface area of ​​the clay mineral is 450 m². 2 / kg, the clay minerals are attapulgite and metakaolinite, and the mass ratio of attapulgite to metakaolinite is 1:2.

[0059] In this embodiment, the electrolytic manganese slag has a pH value of 6.5, a SiO2 content of 44 wt.%, and an Al2O3 content of 28 wt.%.

[0060] In this embodiment, the modified sepiolite was prepared using the following steps: a specific surface area of ​​250 m² was used to prepare the sepiolite. 2 / kg of sepiolite was pre-ground in a zirconia planetary ball mill at a speed of 60 r / min to a specific surface area of ​​349.2 m². 2 / kg, acidified with 5mol / mL sulfuric acid solution for 60s, then ground to a specific surface area of ​​400m². 2 / kg, and finally the pH value was adjusted to 7.0 with Ca(OH)2 with an effective content of 89wt.%, and after drying, modified sepiolite was obtained.

[0061] In this embodiment, the phosphorus-containing waste is modified phosphogypsum. The effective water-soluble phosphorus and eutectic phosphorus content of the phosphogypsum before modification is 1.1 wt.%.

[0062] Weigh 50 parts of slag sulfoaluminate cement and 30 parts of high belite sulfoaluminate cement clinker and mix them in a V-type mixer for 10 minutes to obtain cementitious strength material A2.

[0063] Weigh 10 parts of modified sepiolite, 2 parts of modified phosphogypsum, 5 parts of clay minerals, and 8 parts of electrolytic manganese slag and mix them in a V-type mixer for 10 minutes. Then, place them at 280℃ and mix them at a speed of 50 r / min for 1.5 hours to obtain supplementary modified material B2.

[0064] Mix the cementitious strength material A2 and the supplementary modifier B2 for 40 minutes to obtain the low-alkali, fertilizer-effective slow-release cementitious material for vegetation concrete in this embodiment, denoted as #2.

[0065] Example 3

[0066] As a preferred embodiment of the present invention, this embodiment uses a low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material, the specific composition of which is shown in Table 3:

[0067] Table 3

[0068] Slag sulfoaluminate cement 60 High belite sulfur-aluminum cement clinker 10 Modified sepiolite 6 Phosphate slag 5 Clay minerals (illite:chlorite mass ratio = 2:3) 5 Electrolytic manganese slag 8

[0069] In this embodiment, the heat of hydration of slag sulfoaluminate cement is 136 J / g at 3d and 188 J / g at 7d, and the specific surface area is 420 m². 2 / kg, 3d compressive strength = 36.9MPa, 28d compressive strength = 55.7MPa.

[0070] In this embodiment, the dicalcium silicate content of the high belite sulfur-aluminate cement clinker is 41.0 wt.%, the 3-day compressive strength is 45.5 MPa, and the 28-day compressive strength is 55.9 MPa.

[0071] In this embodiment, the specific surface area of ​​the clay mineral is 400 m². 2 / kg, the clay minerals are illite and chlorite, the mass ratio of illite to chlorite is 2:3, and the chlorite is chlorite powder.

[0072] In this embodiment, the electrolytic manganese slag has a pH value of 6.2, a SiO2 content of 33.7 wt.%, and an Al2O3 content of 25 wt.%.

[0073] In this embodiment, the modified sepiolite was prepared using the following steps: a specific surface area of ​​280 m² was used... 2 / kg of sepiolite was pre-ground in a zirconia planetary ball mill at a speed of 100 r / min to a specific surface area of ​​352.9 m². 2 / kg, add 2.1mol / mL sulfuric acid solution, acidify for 30s, and then grind to a specific surface area of ​​430m². 2 / kg, and finally the pH value was adjusted to 7.0 with Ca(OH)2 with an effective content of 90wt.%, and after drying, modified sepiolite was obtained.

[0074] In this embodiment, the phosphorus-containing waste is phosphate slag, and the effective water-soluble phosphorus content of the phosphate slag is 0.8 wt.%.

[0075] Weigh 60 parts of slag sulfoaluminate cement and 10 parts of high belite sulfoaluminate cement clinker and mix them in a V-type mixer for 8 minutes to obtain cementitious strength material A3.

[0076] Weigh 6 parts of modified sepiolite, 5 parts of phosphate slag, 5 parts of clay minerals, and 8 parts of electrolytic manganese slag and mix them in a V-type mixer for 10 minutes. Then, place them at 300℃ and mix them at a speed of 50 r / min for 1.2 hours to obtain supplementary modified material B3.

[0077] The cementitious strength material A3 and the supplementary modifier B3 were mixed for 35 minutes to obtain the low-alkali, fertilizer-effect slow-release cementitious material for vegetation concrete in this embodiment, denoted as #3.

[0078] Example 4

[0079] As a preferred embodiment of the present invention, this embodiment uses a low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material, the specific composition of which is shown in Table 4:

[0080] Table 4

[0081] Slag sulfoaluminate cement 60 High belite sulfur-aluminum cement clinker 3 Modified sepiolite 10 Phosphate slag 2 Clay minerals (illite:chlorite mass ratio = 2:3) 5 Electrolytic manganese slag 8

[0082] In this embodiment, the heat of hydration of slag sulfoaluminate cement is 140 J / g at 3d and 192 J / g at 7d, and the specific surface area is 430 m². 2 / kg, 3d compressive strength = 35.5MPa, 28d compressive strength = 55.0MPa.

[0083] In this embodiment, the dicalcium silicate content of the high belite sulfur-aluminate cement clinker is 42.0 wt.%, the 3-day compressive strength is 43.5 MPa, and the 28-day compressive strength is 58.2 MPa.

[0084] In this embodiment, the specific surface area of ​​the clay mineral is 400 m². 2 / kg, the clay minerals are attapulgite and metakaolinite, and the mass ratio of illite to chlorite is 2:3.

[0085] In this embodiment, the electrolytic manganese slag has a pH value of 6.2, a SiO2 content of 33.0 wt.%, and an Al2O3 content of 30.0 wt.%.

[0086] In this embodiment, the modified sepiolite was prepared using the following steps: a specific surface area of ​​300 m² was used to prepare the sepiolite. 2 / kg of sepiolite was pre-ground in a zirconia planetary ball mill at a speed of 80 r / min to a specific surface area of ​​367.2 m². 2 / kg, acidified with 1.5mol / mL sulfuric acid solution for 45s, then ground to a specific surface area of ​​411m². 2 / kg, and finally the pH value was adjusted to 6.9 with Ca(OH)2 with an effective content of 90wt.%, and the modified sea stone was obtained after drying.

[0087] In this embodiment, the phosphorus-containing waste is phosphate slag, and the effective water-soluble phosphorus content of the phosphate slag is 1.0 wt.%.

[0088] Weigh 60 parts of slag sulfoaluminate cement and 3 parts of high belite sulfoaluminate cement clinker and mix them in a V-type mixer for 5 minutes to obtain cementitious strength material A4.

[0089] Weigh 10 parts of modified sepiolite, 2 parts of phosphate slag, 5 parts of clay minerals, and 8 parts of electrolytic manganese slag and mix them in a V-type mixer for 10 minutes. Then, place them at 290℃ and mix at a speed of 50 r / min for 2.5 hours to obtain supplementary modified material B4.

[0090] The cementitious strength material A4 and the supplementary modifier B4 were mixed for 35 minutes to obtain the low-alkali, fertilizer-effect slow-release cementitious material for vegetation concrete in this embodiment, denoted as #4.

[0091] Example 5

[0092] As a preferred embodiment of the present invention, this embodiment uses a low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material, the specific composition of which is shown in Table 5:

[0093] Table 5

[0094] Slag sulfoaluminate cement 50 High belite sulfur-aluminum cement clinker 20 Modified sepiolite 7 Phosphate slag 3 Clay minerals (illite:chlorite mass ratio = 2:3) 2 Electrolytic manganese slag 12

[0095] In this embodiment, the heat of hydration of slag sulfoaluminate cement is 140 J / g at 3d and 192 J / g at 7d, and the specific surface area is 430 m². 2 / kg, 3d compressive strength = 35.5MPa, 28d compressive strength = 55.0MPa.

[0096] In this embodiment, the dicalcium silicate content of the high belite sulfur-aluminate cement clinker is 42.0 wt.%, the 3-day compressive strength is 43.5 MPa, and the 28-day compressive strength is 58.2 MPa.

[0097] In this embodiment, the specific surface area of ​​the clay mineral is 400 m². 2 / kg, the clay minerals are attapulgite and metakaolinite, and the mass ratio of illite to chlorite is 2:3.

[0098] In this embodiment, the electrolytic manganese slag has a pH value of 6.2, a SiO2 content of 33.0 wt.%, and an Al2O3 content of 30.0 wt.%.

[0099] In this embodiment, the modified sepiolite was prepared using the following steps: a specific surface area of ​​280 m² was used... 2 / kg of sepiolite was pre-ground in a zirconia planetary ball mill at a speed of 80 r / min to a specific surface area of ​​349.2 m². 2 / kg, acidified with 1.5mol / mL sulfuric acid solution for 45s, then ground to a specific surface area of ​​411m². 2 / kg, and finally the pH value was adjusted to 6.9 with Ca(OH)2 with an effective content of 90wt.%, and after drying, modified sepiolite was obtained.

[0100] In this embodiment, the phosphorus-containing waste is phosphate slag, and the effective water-soluble phosphorus content of the phosphate slag is 1.3 wt.%.

[0101] Weigh 50 parts of slag sulfoaluminate cement and 20 parts of high belite sulfoaluminate cement clinker and mix them in a V-type mixer for 5 minutes to obtain cementitious strength material A5.

[0102] Weigh 7 parts of modified sepiolite, 3 parts of phosphate rock slag, 2 parts of clay minerals, and 12 parts of electrolytic manganese slag and mix them in a V-type mixer for 10 minutes. Then, place them at 290℃ and mix at a speed of 50 r / min for 2.5 hours to obtain supplementary modified material B5.

[0103] Mix the cementitious strength material A5 and the supplementary modifier B5 for 35 minutes to obtain the low-alkali, fertilizer-effect slow-release cementitious material for vegetation concrete in this embodiment, denoted as #5.

[0104] Comparative Example 1

[0105] Except for the sepiolite, which was not modified, this comparative example was the same as Example 1, and the resulting cementitious material for vegetation concrete was denoted as *1.

[0106] Comparative Example 2

[0107] Except for the absence of phosphorus-containing waste, this comparative example is identical to Example 1, yielding a cementitious material for vegetation concrete, denoted as *2.

[0108] Comparative Example 3

[0109] Except for the absence of electrolytic manganese slag, this comparative example is identical to Example 1, yielding a cementitious material for vegetation concrete, denoted as *3.

[0110] Test case

[0111] According to the test method of GB / T17671, the mortar strength of the base material prepared in Examples 1-5 and Comparative Examples 1-3 was tested. Specimens were formed using a mix proportion of 35 kg cementitious material + 165 kg planting soil (base layer) + 75 kg coarse sand (particle size controlled between 0.05-1.0 cm) + 0.2 kg supplementary organic matter + 9 kg mixing water for vegetated concrete. Surface cracking, unconfined compressive strength, pH value, total nitrogen content, water-soluble phosphorus, and nutrient release (cumulative nutrient release rate over 28 days) were tested using visual inspection, GB / T50123, JCT 2557, GB / T8572, GB / T8537, and GB / T 23348. The performance of each cementitious material and the corresponding vegetated concrete is shown in Table 6.

[0112] Table 6

[0113]

[0114] According to the test data in Table 6, the cementitious material has a low alkalinity (pH value), low heat of hydration, and high early and later strength. It can also provide water for the hydration of the cementitious material in the vegetation concrete, serving as an internal curing material, effectively improving the early crack resistance of the concrete. In the later stages of concrete preparation and application, after natural water replenishment, the sufficient water storage framework can alleviate the water demand of vegetation during the dry season. By using industrial solid waste materials and being able to reasonably and effectively adjust the pH value of the cementitious material, the prepared vegetation concrete has a wide pH range that is conducive to plant seed germination and root development, loads effective fertilizers, and slowly releases fertilizer effects.

[0115] The experimental data from Comparative Example 1 show that the modified sepiolite in the cementitious material system functions as a load for nutrient ions and adsorbs water used for self-curing concrete, effectively loading nutrient ions and functional groups. The experimental data from Comparative Example 2 show that the phosphorus-containing waste provides essential phosphorus for plant growth, and when combined with other materials, it provides a more reasonable particle size distribution, activates slag to improve slag hydration activity, and enhances the early and mid-to-late stage mortar strength of the cementitious material. The experimental data from Comparative Example 3 show that the electrolytic manganese slag in the cementitious material system effectively regulates the pH value, provides a reasonable particle size distribution, and provides nitrogen for plant growth in the concrete base layer.

[0116] Finally, it should be noted that the above embodiments are merely preferred embodiments of the present invention used to illustrate the technical solutions of the present invention, and are not intended to limit the invention, nor are they intended to limit the patent scope of the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention. That is to say, any changes or refinements made to the main design concept and spirit of the present invention that are not of substantial significance, but whose technical problems are still consistent with the present invention, should be included within the protection scope of the present invention. In addition, the direct or indirect application of the technical solutions of the present invention to other related technical fields are similarly included within the patent protection scope of the present invention.

Claims

1. A low-alkali, slow-release fertilizer-effect cementitious material for vegetation concrete, characterized in that, Includes the following raw materials in parts by weight: 40-65 parts of slag sulfoaluminate cement; 3-30 parts of high-belite sulfur-aluminate cement clinker; 5-10 parts of modified sepiolite; 2-5 portions of phosphorus-containing waste; 1-5 parts of clay minerals; 2-12 parts of electrolytic manganese slag; Modified sepiolite is prepared by the following steps: [The text abruptly shifts to a different topic] ...with a specific surface area of ​​250-300 m²... 2 / kg of sepiolite was pre-ground to a specific surface area of ​​350±20m². 2 / kg, acidified with sulfuric acid solution and then ground to a specific surface area of ​​450±50m² 2 / kg, and finally the pH value was adjusted to 6.9-7.2 with Ca(OH)2, and after drying, modified sepiolite was obtained; The concentration of the sulfuric acid solution is 1-5 mol / mL, and the effective content of Ca(OH)₂ is 85-95 wt.%. Phosphorus-containing waste includes phosphate slag or modified phosphogypsum; The modified phosphogypsum, after calcination at 300℃ for 30 min, exhibits an effective water-soluble phosphorus and eutectic phosphorus content ≥1.0 wt.% compared to the unmodified phosphogypsum; the effective water-soluble phosphorus content of the phosphate rock slag is ≥0.8 wt.%. The electrolytic manganese slag has a pH value of 6.0-7.2, a SiO2 content of 33-50 wt.%, and an Al2O3 content of 14-30 wt.%.

2. The low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material according to claim 1, characterized in that, The rotation speed for pre-grinding and grinding is 60-100 r / min, and the grinding time is 20-60 s. A zirconia planetary ball mill is used for pre-grinding and grinding.

3. The low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material according to claim 1, characterized in that, The specific surface area of ​​clay minerals is 380-450 m². 2 / kg, the clay minerals are any one or two of montmorillonite, illite, attapulgite, chlorite, and metakaolinite.

4. The low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material according to claim 1, characterized in that, The heat of hydration of slag sulfoaluminate cement is ≤150 J / g at 3d and ≤200 J / g at 7d, and its specific surface area is 430±20 m². 2 / kg.

5. The low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material according to claim 1, characterized in that, The dicalcium silicate content of high belite sulfur-aluminate cement clinker is not less than 40 wt.%, and the 3-day compressive strength is ≥42.5 MPa and the 28-day compressive strength is ≥52.5 MPa.

6. A method for preparing a low-alkali, fertilizer-efficient slow-release cementitious material for vegetation concrete according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Weigh 40-65 parts of slag sulfoaluminate cement and 3-30 parts of high belite sulfoaluminate cement clinker and mix for 5-10 minutes to obtain cementitious strength material A. Step 2: Weigh 5-10 parts of modified sepiolite, 2-5 parts of phosphorus-containing waste, 1-5 parts of clay minerals, and 2-12 parts of electrolytic manganese slag, mix for 10-15 minutes, and then place at 250-300℃ for high-temperature mixing for 2-2.5 hours to obtain supplementary modified material B. Step 3: Mix the cementitious strength material A and the supplementary modifier B for 30-40 minutes to obtain the low-alkali, fertilizer-effect slow-release cementitious material for vegetation concrete.

7. The method for preparing a low-alkali, fertilizer-efficacy slow-release cementitious material for vegetation concrete according to claim 6, characterized in that, A V-type mixer is used for mixing in steps 1 and 3.

8. The method for preparing a low-alkali, slow-release fertilizer-effect vegetation concrete cementitious material according to claim 6, characterized in that, The mixing in step 2 was carried out in a roller high-temperature furnace at a speed of 50 r / min.

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