Phosphogypsum slope base material with balanced comprehensive performance and shear strength and preparation method of phosphogypsum slope base material

Abstract

The invention discloses an ardealite slope base material with balanced comprehensive performance and shear strength and a preparation method of the ardealite slope base material. The ardealite slope base material comprises 48-62 wt% of excavation soil, 5-7 wt% of construction waste recycled aggregate, 8-23 wt% of ardealite, 0.3-0.5 wt% of perlite and 20-25 wt% of water. The preparation method comprises the following steps: putting excavation soil with various particle sizes, low-brick-concrete construction waste recycled aggregate with various particle sizes, high-brick-concrete construction waste recycled aggregate with various particle sizes and perlite into a stirrer, and stirring at a low speed to form a solid mixture; adding water into the stirrer, and stirring with the solid mixture at a low speed to form mixed slurry; adding ardealite into the stirrer, and sequentially performing low-speed stirring, high-speed stirring and low-speed stirring on the ardealite and the mixed slurry to obtain the ardealite slope base material with balanced comprehensive performance and shear strength. The problems that in the prior art, the comprehensive performance and shear strength of a slope base material are unbalanced, the production process is complex, and raw materials excessively depend on natural minerals and high-quality nutrient soil are solved.

Description

Technical Field

[0001] The invention belongs to the technical field of road engineering and environmental engineering, and specifically relates to a phosphogypsum slope base material with balanced comprehensive performance and shear strength and a preparation method thereof. Background Art

[0002] As we all know, the construction of highways, railways, rivers and other projects has caused damage to the surrounding geological environment, resulting in a large number of exposed rock or soil slopes, leading to soil erosion, frequent geological disasters, reduced species diversity and other problems. Spraying slope substrate is an effective way to improve the ecological environment of slopes, but the slope substrate of the existing technology still has many problems.

[0003] In order to address the complex terrain areas with serious ecological damage, experts in related fields at home and abroad have developed many new technologies, such as using anchor cables and other support structures to reinforce the hillside, or using shotcrete for anti-collapse support, but traditional "gray" technologies are not enough to restore the ecosystem. Some ecological experts have turned their attention to vegetation reconstruction technology, such as grass slope protection, vine slope protection and other greening technologies, in order to achieve the effect of restoring the damaged ecological environment while stabilizing the slope, but the vegetation reconstruction slope protection technology requires laying porous concrete on the surface of the slope soil and filling the gaps with nutrients and seeds. In this method, laying concrete is difficult and costly, and it is also necessary to add water and nutrients that are conducive to seed growth, which makes maintenance more difficult.

[0004] The slope substrate should have strong viscosity, so that the slope has better resistance to rain erosion, prevents the slope from weathering and peeling, and increases the stability of the slope. The slope substrate of the prior art relies on cement or fly ash as a bonding material to stabilize the soil in order to obtain a slope substrate with low alkalinity and high stability at the same time, but the presence of cement is not conducive to plant growth. If the cement content in the slope substrate is too low, the bonding strength is insufficient, resulting in the fall-off between the slope substrate and the slope surface. If the cement content in the slope substrate is too high, the pH value increases, which is not conducive to vegetation growth. The measures currently taken are to use materials such as gypsum, ceramsite, fly ash, low-alkali cement, and polymer curing agents to take into account the slope protection ability and alkali reduction ability of the slope substrate, change the physical and chemical properties of the slope substrate, and make it suitable for plant growth. However, when these materials are used to prepare the slope substrate, its comprehensive performance and shear strength cannot be balanced.

[0005] The slope substrate needs to provide the necessary soil aggregate structure, balanced gas, solid and liquid phases, and sufficient nutrients for vegetation growth, and should have a certain water retention capacity to increase the growth effect of plants. The existing slope substrate improves the fertility and nutrient content of the slope substrate by adding high-quality nutrient soil and fertilizers, but in actual use, it is easy to cause soil acidification and compaction, which brings environmental pollution. The fertilizer retention performance of the slope substrate is poor. Due to degradation, nutrients are lost quickly and cannot continuously provide nutrients for plant growth, resulting in serious degradation of vegetation after several years of spraying; the water retention capacity of the slope substrate is poor, resulting in the difficulty of the foreign soil layer in the arid northern region to ensure the water required for plant growth. It can be seen that it is necessary to regularly supplement and maintain the nutrients and water in the slope substrate, which greatly increases the construction and operation costs.

[0006] The preparation of slope substrates often requires a large amount of cultivated soil (i.e. fertile soil dug from fields), which will cause secondary damage to the ecological environment. Other waste materials with similar functions can be studied to replace cultivated soil. In addition, the slope substrate needs to have a certain shear resistance, which needs to be achieved by adding cement. However, adding cement will cause the comprehensive performance of the slope substrate to deteriorate. Therefore, it is urgent to develop a phosphogypsum slope substrate with balanced comprehensive performance and shear strength and its preparation method, which can not only meet the needs of the slope, but also provide an excellent environment for plant growth, while being low-cost.

[0007] The invention patent with application publication number CN111387010A discloses a method for preparing slope greening matrix material from phosphogypsum, which includes the following steps: rough processing of raw materials, mixing phosphogypsum and building stone waste residue and sending them into a centrifugal mixer for crushing, and sending kitchen waste into a biogas tank for fermentation treatment; fine processing of raw materials, sending the crushed phosphogypsum and building stone waste residue into a screening machine for screening, collecting raw materials with a particle size of less than 2 mm as solid materials for subsequent processes, fermenting in a biogas tank to produce biogas, and sending the remaining The wastewater and waste mixture in the base material is dehydrated to obtain carbon-containing organic matter with a water content of 10-15% after dehydration; the raw materials are mixed and dried, the solid materials and carbon-containing organic matter are mixed, nutrient solution is added, and the mixture is sent to a mixer for uniform mixing, and the mixed material is sent to a rotary kiln for drying to obtain dry granular powder; the road slope greening matrix material is prepared by taking the dry granular powder and the bottom mud of the domestic sewage treatment plant, mixing them, and sending them to a large mixer for uniform mixing to prepare the road slope greening matrix material. Although the slope base material prepared by this technical solution has both the ability of concrete to solidify the slope and the ability of the soil layer to provide green plants for growth, the comprehensive performance of the base material and the shear strength cannot reach a balance, and the technical solution does not record any test data on the shear performance and comprehensive performance of the slope base material. Summary of the invention

[0008] In order to solve the problems existing in the prior art, the present invention provides a phosphogypsum slope base material with balanced comprehensive performance and shear strength. The mass percentage of each substance in the phosphogypsum slope base material is as follows: excavated soil accounts for 48-62wt%, recycled aggregate of construction waste accounts for 5-7wt%, phosphogypsum accounts for 8-23wt%, perlite accounts for 0.3-0.5wt%, and water accounts for 20-25wt%; the ratio of the mass of the phosphogypsum to the sum of the mass of the excavated soil, the recycled aggregate of construction waste, the phosphogypsum and the perlite is 0.1-0.3:1; the mass percentage of each substance in the recycled aggregate of construction waste accounts for as follows: low brick-concrete recycled aggregate of construction waste accounts for 75-80wt%, and high brick-concrete recycled aggregate of construction waste accounts for 20-25wt%.

[0009] Preferably, the excavated soil is soil excavated by manual or mechanical excavation during road construction; the pH value of the excavated soil is less than 8, and each kilogram of excavated soil contains no less than 7g of organic matter.

[0010] In any of the above schemes, it is preferred that the excavated soil includes six particle sizes, and the mass percentage of each particle size in the excavated soil is: particle size 1.18-2mm accounts for 15-20wt%, particle size 0.6-1.18mm accounts for 16-21wt%, particle size 0.3-0.6mm accounts for 18-23wt%, particle size 0.15-0.3mm accounts for 17-22wt%, particle size 0.075-0.15mm accounts for 10-15wt%, and particle size 0-0.075mm accounts for 7-12wt%.

[0011] In any of the above schemes, it is preferred that the low-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of concrete buildings, and its brick-concrete content is 10-30wt%; the high-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of brick-concrete buildings, and its brick-concrete content is 70-80wt%.

[0012] In any of the above schemes, it is preferred that the low-brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size of the low-brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 10-15wt%, particle size 0.6-1.18mm accounts for 10-15wt%, particle size 0.3-0.6mm accounts for 15-20wt%, particle size 0.15-0.3mm accounts for 25-30wt%, particle size 0.075-0.15mm accounts for 25-30wt%, particle size 0-0.075mm accounts for 5-10wt%.

[0013] In any of the above schemes, it is preferred that the high-brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size of the high-brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 10-15wt%, particle size 0.6-1.18mm accounts for 20-25wt%, particle size 0.3-0.6mm accounts for 20-25wt%, particle size 0.15-0.3mm accounts for 15-20wt%, particle size 0.075-0.15mm accounts for 15-20wt%, and particle size 0-0.075mm accounts for 10-15wt%.

[0014] In any of the above schemes, preferably, the mass of calcium sulfate dihydrate contained in the phosphogypsum is 80-95wt%, the pH value of the phosphogypsum is less than 7; and the phosphogypsum includes a particle size of 5-50μm.

[0015] In any of the above schemes, preferably, the particle size of the perlite is not greater than 2 mm and the density is 2.3 g / cm 3 , the water absorption rate is 238%.

[0016] The present invention also provides a method for preparing a phosphogypsum slope substrate with a balance of comprehensive performance and shear strength, which is used to prepare the phosphogypsum slope substrate with a balance of comprehensive performance and shear strength as described in any one of the above items, and comprises the following steps in order: Step 1: weighing excavated soil of various particle sizes, low-brick-concrete construction waste recycled aggregate of various particle sizes, high-brick-concrete construction waste recycled aggregate of various particle sizes, phosphogypsum, perlite, and water according to design requirements for later use;

[0017] Step 2: putting excavated soil of various particle sizes, low-brick-concrete construction waste recycled aggregate of various particle sizes, high-brick-concrete construction waste recycled aggregate of various particle sizes, and perlite into a mixer and stirring at a low speed to form a solid mixture;

[0018] Step 3: Add water into the mixer and stir it with the solid mixture at a low speed to form a mixed slurry;

[0019] Step 4: Add phosphogypsum into a mixer and stir it with the mixed slurry three times, in the order of low-speed stirring, high-speed stirring and low-speed stirring. After three stirrings, a phosphogypsum slope base material with balanced comprehensive performance and shear strength can be obtained.

[0020] Preferably, in step 2, the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 1-2min, and the stirring temperature is room temperature; in step 3, the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 30-60s, and the stirring temperature is room temperature; in step 4, the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 30-60s, and the stirring temperature is room temperature, the stirring rate of high-speed stirring is 200-300r / min, the stirring time is 60-90s, and the stirring temperature is room temperature, and the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 30-60s, and the stirring temperature is room temperature.

[0021] In the present invention, the low-brick-concrete construction waste recycled aggregate is the construction waste generated by the demolition of concrete buildings, and its brick-concrete content is 10-30wt%. The high-brick-concrete construction waste recycled aggregate is the construction waste generated by the demolition of brick-concrete buildings, and its brick-concrete content is 70-80wt%. The brick-concrete content here specifically refers to the content of non-concrete substances such as bricks, tiles, and red brick fragments in the construction waste recycled aggregate.

[0022] The particle sizes of excavated soil and recycled aggregates from construction waste are 1.18-2mm, 0.6-1.18mm, 0.3-0.6mm, 0.15-0.3mm, 0.075-0.15mm, and 0-0.075mm, i.e., 1.18mm≤particle size<2mm, 0.6mm≤particle size<1.18mm, 0.3mm≤particle size<0.6mm, 0.15mm≤particle size<0.3mm, 0.075mm≤particle size<0.15mm, and 0mm<particle size<0.075mm; the particle size of phosphogypsum is 5-50μm, i.e., 5μm≤particle size<50μm. For each particle size, the material passes through the upper and lower sieve holes in sequence to obtain a particle size between the upper and lower sieve holes, for example: the particle size is 1.18-2mm (1.18mm≤particle size<2mm), that is, the material passes through the 2mm sieve hole and the 1.18mm sieve hole in sequence to obtain a particle size between 1.18-2mm.

[0023] Phosphogypsum contains nutrients necessary for vegetation, such as P, S, Ca, Si, N, K, etc. It promotes plant growth, activates plant enzymes, improves quality, and enhances disease and drought resistance. Phosphogypsum used in soil can reduce shrinkage rate and increase soil permeability and air permeability.

[0024] In the entire preparation process of the phosphogypsum slope substrate, the mass percentage of each component, the mass ratio of each particle size in each component, the order of adding each component, the process parameters of each step, etc. are all very critical. Only by synergizing various parameters can the expected technical effect of the present invention be achieved.

[0025] The phosphogypsum slope substrate prepared by the present invention has the following characteristics in terms of function and effect: 1. strong comprehensive performance, can provide the necessary soil aggregate structure, balanced gas, solid, liquid phases and nutrients for vegetation growth, and has a certain water retention capacity; 2. high shear strength, the slope substrate has strong viscosity, can make the slope have better resistance to rain erosion, prevent slope weathering and peeling, and increase the stability of the slope; 3. local materials are used, waste can be fully utilized as raw materials, and material costs are reduced.

[0026] The phosphogypsum slope substrate with balanced comprehensive performance and shear strength and the preparation method thereof of the present invention have the following beneficial effects:

[0027] (1) The present invention uses phosphogypsum as a cementing component, and makes full use of its gelling effect to improve the texture of the substrate, so that the substrate can be organically combined with the surface, provide early strength and adhesion for the slope substrate, improve the anti-rainwater erosion performance of the slope substrate, and effectively prevent the loss and weathering of the substrate, thereby increasing the stability of the slope. At the same time, phosphogypsum can be used as a soil salinity modifier, and can also be used as a low-grade fertilizer, and has a certain water retention capacity, taking into account the effects of reducing the alkalinity of the substrate, increasing the nutrients of the substrate, improving the structure of the soil, and improving the permeability of the soil. Phosphogypsum can provide the necessary soil aggregate structure, balanced gas, solid, liquid phases and nutrients for vegetation growth, promote plant growth, increase the activity of plant enzymes, improve the quality of plants, and can enhance the disease resistance and drought resistance of plants, thereby improving the restoration effect of vegetation.

[0028] (2) The perlite used in the present invention can be used as one of the soil improvement components to reduce the bulk density of the slope substrate and improve its water retention capacity, thereby achieving the goal of green ecological restoration.

[0029] (3) The present invention uses a large amount of sustainable materials in both aggregate and binder components, wherein phosphogypsum as a binder accounts for 8-23%. Excavated soil is used as sandy soil, and construction demolition waste is used as regenerated sand, with the proportion of construction demolition waste accounting for 5-7%. Local materials are used to maximize the use of solid waste, balance the pH value in the soil and compensate for the water loss shrinkage of the soil, which greatly reduces the dependence of slope greening repair materials on non-renewable resources such as cement and stone, helps to alleviate the problem of existing materials being highly dependent on non-renewable resources, and reduces material costs.

[0030] (4) The present invention does not consume excessive energy during the production and construction process, and does not generate waste gas, dust and other pollution, which greatly reduces the environmental protection of the entire production, construction and maintenance process. At the same time, the slope base material is mainly composed of excavated soil (sand), construction waste recycled aggregate (recycled sand), phosphogypsum, perlite and water. The raw material composition is simple, the construction process is simplified, and solid waste is utilized to the greatest extent, achieving sustainable development of resources.

[0031] (5) The present invention mainly solves the problems in the prior art, such as the imbalance between the comprehensive performance and shear strength of the slope substrate, the complex production process, and the excessive reliance on natural minerals such as cement and high-quality nutrient soil for raw materials. The slope substrate prepared by the present invention is more suitable for the arid slopes in the north. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 A flowchart of a preferred embodiment of a phosphogypsum slope substrate having a balance between comprehensive performance and shear strength and a preparation method thereof according to the present invention;

[0033] Figure 2 The photos are of the mixing process of the phosphogypsum slope substrate in three embodiments;

[0034] Figure 3 The photos of the curing process of the specimens of the phosphogypsum slope substrate in the three embodiments;

[0035] Figure 4 The fluidity test photos of the phosphogypsum slope substrate in three embodiments are shown in FIG. 1 , wherein: (a) is a fluidity test photo of Embodiment 1, (b) is a fluidity test photo of Embodiment 2, and (c) is a fluidity test photo of Embodiment 3;

[0036] Figure 5 The photos are of the shear test process of the phosphogypsum slope substrate in three embodiments;

[0037] Figure 6 The shear resistance fitting curves of the phosphogypsum slope substrate in the three embodiments are shown in FIG. DETAILED DESCRIPTION

[0038] In order to further understand the content of the present invention, the present invention will be described in detail below in conjunction with specific embodiments.

[0039] Embodiment 1:

[0040] According to a preferred embodiment of the phosphogypsum slope substrate with balanced comprehensive performance and shear strength of the present invention, the mass percentage of each substance in the phosphogypsum slope substrate is 55wt% of excavated soil, 6wt% of construction waste recycled aggregate, 16wt% of phosphogypsum, 0.4wt% of perlite, and 22.6wt% of water; the ratio of the mass of the phosphogypsum to the sum of the mass of the excavated soil, the construction waste recycled aggregate, the phosphogypsum, and the perlite is 0.21:1; the mass percentage of each substance in the construction waste recycled aggregate is 78wt% of low-brick-concrete construction waste recycled aggregate and 22wt% of high-brick-concrete construction waste recycled aggregate.

[0041] The excavated soil is the soil dug out by manual or mechanical excavation during road construction; the pH value of the excavated soil is 7.1, and the organic matter content of each kilogram of excavated soil is 8.2g. The excavated soil includes six particle sizes, and the mass percentage of each particle size in the excavated soil is as follows: particle size 1.18-2mm accounts for 18wt%, particle size 0.6-1.18mm accounts for 19wt%, particle size 0.3-0.6mm accounts for 20wt%, particle size 0.15-0.3mm accounts for 20wt%, particle size 0.075-0.15mm accounts for 13wt%, and particle size 0-0.075mm accounts for 10wt%.

[0042] The low-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of concrete buildings, and its brick-concrete content is 20wt%. The low-brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size in the low-brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 12wt%, particle size 0.6-1.18mm accounts for 12wt%, particle size 0.3-0.6mm accounts for 17wt%, particle size 0.15-0.3mm accounts for 26wt%, particle size 0.075-0.15mm accounts for 26wt%, and particle size 0-0.075mm accounts for 7wt%.

[0043] The high-grade brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of brick-concrete buildings, and its brick-concrete content is 75wt%. The high-grade brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size in the high-grade brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 12wt%, particle size 0.6-1.18mm accounts for 22wt%, particle size 0.3-0.6mm accounts for 22wt%, particle size 0.15-0.3mm accounts for 16wt%, particle size 0.075-0.15mm accounts for 16wt%, and particle size 0-0.075mm accounts for 12wt%.

[0044] The mass of calcium sulfate dihydrate contained in the phosphogypsum is 88.21wt%, and the pH value of the phosphogypsum is 6.8; the phosphogypsum includes a particle size of 5-50μm. The particle size of the perlite is 2mm and the density is 2.3g / cm 3 , the water absorption rate is 238%.

[0045] like Figure 1 As shown, this embodiment also provides a method for preparing a phosphogypsum slope substrate with a balance between comprehensive performance and shear strength, which is used to prepare the phosphogypsum slope substrate with a balance between comprehensive performance and shear strength, and includes the following steps in order:

[0046] Step 1: According to the design requirements, weigh the excavated soil of various particle sizes, the recycled aggregate of low-density brick-concrete construction waste of various particle sizes, the recycled aggregate of high-density brick-concrete construction waste of various particle sizes, phosphogypsum, perlite and water for later use;

[0047] Step 2: putting excavated soil of various particle sizes, low-brick-concrete construction waste recycled aggregate of various particle sizes, high-brick-concrete construction waste recycled aggregate of various particle sizes, and perlite into a mixer and stirring at a low speed to form a solid mixture;

[0048] Step 3: Add water into the mixer and stir it with the solid mixture at a low speed to form a mixed slurry;

[0049] Step 4: Add phosphogypsum into a mixer and stir it with the mixed slurry three times, in the order of low-speed stirring, high-speed stirring and low-speed stirring. After three stirrings, a phosphogypsum slope base material with balanced comprehensive performance and shear strength can be obtained.

[0050] In step 2, the stirring rate of low-speed stirring is 115r / min, the stirring time is 1.5min, and the stirring temperature is room temperature; in step 3, the stirring rate of low-speed stirring is 115r / min, the stirring time is 45s, and the stirring temperature is room temperature; in step 4, the stirring rate of low-speed stirring is 115r / min, the stirring time is 45s, and the stirring temperature is room temperature, the stirring rate of high-speed stirring is 250r / min, the stirring time is 75s, and the stirring temperature is room temperature, and the stirring rate of low-speed stirring is 115r / min, the stirring time is 45s, and the stirring temperature is room temperature.

[0051] In this embodiment, the brick-concrete content specifically refers to the content of non-concrete materials such as bricks and tiles, red brick fragments, etc. in the recycled aggregate of construction waste. The particle sizes of excavated soil and recycled aggregate of construction waste are 1.18-2mm, 0.6-1.18mm, 0.3-0.6mm, 0.15-0.3mm, 0.075-0.15mm, 0-0.075mm, that is, 1.18mm≤particle size<2mm, 0.6mm≤particle size<1.18mm, 0.3mm≤particle size<0.6mm, 0.15mm≤particle size<0.3mm, 0.075mm≤particle size<0.15mm, 0mm<particle size<0.075mm; the particle size of phosphogypsum is 5-50μm, that is, 5μm≤particle size<50μm. For each particle size, the material is passed through the upper and lower sieve holes in sequence to obtain a material with a particle size between the upper and lower sieve holes, for example: the particle size is 1.18-2mm (1.18mm≤particle size<2mm), that is, the material is passed through the 2mm sieve hole and the 1.18mm sieve hole in sequence to obtain a material with a particle size between 1.18-2mm. In the entire preparation process of the phosphogypsum slope substrate, the mass percentage of each component, the mass ratio of each particle size in each component, the order of addition of each component, the process parameters of each step, etc. are very critical. Only by synergizing the various parameters can the expected technical effect of this embodiment be achieved.

[0052] The phosphogypsum slope substrate prepared in this embodiment has the following features in terms of function and effect: ① It has strong comprehensive performance and can provide the necessary soil aggregate structure, balanced gas, solid, liquid phases and nutrients for vegetation growth, and has a certain water retention capacity; ② It has high shear strength and the slope substrate has strong viscosity, which can make the slope have better resistance to rain erosion, prevent the slope from weathering and peeling, and increase the stability of the slope; ③ It uses local materials and can make full use of waste as raw materials, reducing material costs.

[0053] The phosphogypsum slope substrate with balanced comprehensive performance and shear strength and the preparation method thereof in this embodiment have the following beneficial effects:

[0054] (1) Use phosphogypsum as a cementing component, make full use of its gelling effect to improve the texture of the substrate, make the substrate organically combined with the surface, provide early strength and adhesion for the slope substrate, improve the slope substrate's resistance to rainwater erosion, effectively prevent the loss and weathering of the substrate, and increase the stability of the slope. At the same time, phosphogypsum can be used as a soil salinity modifier, and can also be used as a low-grade fertilizer, and has a certain water retention capacity, taking into account the effects of reducing the alkalinity of the substrate, improving the nutrients of the substrate, improving the soil structure, and improving the permeability of the soil. Phosphogypsum can provide the necessary soil aggregate structure for vegetation growth, balanced gas, solid, liquid phases and nutrients, promote plant growth, improve plant enzyme activity, improve plant quality, and enhance plant disease resistance and drought resistance. (2) Use local materials, make the most of solid waste, balance the pH in the soil and compensate for soil water loss and shrinkage, greatly reducing the dependence of slope greening restoration materials on non-renewable resources such as cement and stone. (3) It solves the problems in the existing technology, such as the imbalance between the comprehensive performance and shear strength of the slope base material, the complex production process, and the excessive reliance on natural minerals such as cement and high-quality nutrient soil for raw materials.

[0055] Embodiment 2:

[0056] According to another preferred embodiment of the phosphogypsum slope substrate with balanced comprehensive performance and shear strength of the present invention, the components, preparation process, technical principles and beneficial effects of the phosphogypsum slope substrate are basically the same as those of the first embodiment, except that:

[0057] The mass percentage of each substance in the phosphogypsum slope base material is 48wt% of excavated soil, 7wt% of recycled aggregate from construction waste, 23wt% of phosphogypsum, 0.5wt% of perlite and 21.5wt% of water; the ratio of the mass of the phosphogypsum to the sum of the mass of the excavated soil, the recycled aggregate from construction waste, the phosphogypsum and the perlite is 0.29:1; the mass percentage of each substance in the recycled aggregate from construction waste is 75wt% of recycled aggregate from low brick-concrete construction waste and 25wt% of recycled aggregate from high brick-concrete construction waste.

[0058] The excavated soil is the soil dug out by manual or mechanical excavation during road construction; the pH value of the excavated soil is 7.3, and the organic matter content per kilogram of the excavated soil is 7.9g. The excavated soil includes six particle sizes, and the mass percentage of each particle size in the excavated soil is as follows: particle size 1.18-2mm accounts for 15wt%, particle size 0.6-1.18mm accounts for 21wt%, particle size 0.3-0.6mm accounts for 18wt%, particle size 0.15-0.3mm accounts for 22wt%, particle size 0.075-0.15mm accounts for 15wt%, and particle size 0-0.075mm accounts for 9wt%.

[0059] The low-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of concrete buildings, and its brick-concrete content is 10wt%. The low-brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size in the low-brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 10wt%, particle size 0.6-1.18mm accounts for 15wt%, particle size 0.3-0.6mm accounts for 15wt%, particle size 0.15-0.3mm accounts for 30wt%, particle size 0.075-0.15mm accounts for 25wt%, and particle size 0-0.075mm accounts for 5wt%.

[0060] The high-grade brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of brick-concrete buildings, and its brick-concrete content is 70wt%. The high-grade brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size in the high-grade brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 10wt%, particle size 0.6-1.18mm accounts for 25wt%, particle size 0.3-0.6mm accounts for 20wt%, particle size 0.15-0.3mm accounts for 20wt%, particle size 0.075-0.15mm accounts for 15wt%, and particle size 0-0.075mm accounts for 10wt%.

[0061] The mass of calcium sulfate dihydrate contained in the phosphogypsum is 84.58wt%, and the pH value of the phosphogypsum is 6.5; the phosphogypsum includes a particle size of 5-50μm. The particle size of the perlite is 2mm and the density is 2.3g / cm 3 , the water absorption rate is 238%.

[0062] In step 2, the stirring rate of low-speed stirring is 80r / min, the stirring time is 2min, and the stirring temperature is room temperature; in step 3, the stirring rate of low-speed stirring is 80r / min, the stirring time is 60s, and the stirring temperature is room temperature; in step 4, the stirring rate of low-speed stirring is 80r / min, the stirring time is 60s, and the stirring temperature is room temperature, the stirring rate of high-speed stirring is 200r / min, the stirring time is 90s, and the stirring temperature is room temperature, and the stirring rate of low-speed stirring is 80r / min, the stirring time is 60s, and the stirring temperature is room temperature.

[0063] Embodiment three:

[0064] According to another preferred embodiment of the phosphogypsum slope substrate with balanced comprehensive performance and shear strength of the present invention, the components, preparation process, technical principles and beneficial effects of the phosphogypsum slope substrate are basically the same as those of the first embodiment, except that:

[0065] The mass percentage of each substance in the phosphogypsum slope base material is 62wt% of excavated soil, 5wt% of recycled aggregate from construction waste, 8wt% of phosphogypsum, 0.3wt% of perlite, and 24.7wt% of water; the ratio of the mass of the phosphogypsum to the sum of the mass of the excavated soil, the recycled aggregate from construction waste, the phosphogypsum, and the perlite is 0.11:1; the mass percentage of each substance in the recycled aggregate from construction waste is 80wt% of recycled aggregate from low brick-concrete construction waste and 20wt% of recycled aggregate from high brick-concrete construction waste.

[0066] The excavated soil is the soil dug out by manual or mechanical excavation during road construction; the pH value of the excavated soil is 7.4, and the organic matter content of each kilogram of excavated soil is 8.5g. The excavated soil includes six particle sizes, and the mass percentage of each particle size in the excavated soil is as follows: particle size 1.18-2mm accounts for 20wt%, particle size 0.6-1.18mm accounts for 16wt%, particle size 0.3-0.6mm accounts for 23wt%, particle size 0.15-0.3mm accounts for 17wt%, particle size 0.075-0.15mm accounts for 12wt%, and particle size 0-0.075mm accounts for 12wt%.

[0067] The low-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of concrete buildings, and its brick-concrete content is 30wt%. The low-brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size in the low-brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 14wt%, particle size 0.6-1.18mm accounts for 10wt%, particle size 0.3-0.6mm accounts for 18wt%, particle size 0.15-0.3mm accounts for 25wt%, particle size 0.075-0.15mm accounts for 28wt%, and particle size 0-0.075mm accounts for 5wt%.

[0068] The high-grade brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of brick-concrete buildings, and its brick-concrete content is 80wt%. The high-grade brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size in the high-grade brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 14wt%, particle size 0.6-1.18mm accounts for 20wt%, particle size 0.3-0.6mm accounts for 24wt%, particle size 0.15-0.3mm accounts for 15wt%, particle size 0.075-0.15mm accounts for 17wt%, and particle size 0-0.075mm accounts for 10wt%.

[0069] The mass of calcium sulfate dihydrate contained in the phosphogypsum is 91.8wt%, and the pH value of the phosphogypsum is 6.4; the phosphogypsum includes a particle size of 5-50μm. The particle size of the perlite is 2mm and the density is 2.3g / cm 3 , the water absorption rate is 238%.

[0070] In step 2, the stirring rate of low-speed stirring is 150r / min, the stirring time is 1min, and the stirring temperature is room temperature; in step 3, the stirring rate of low-speed stirring is 150r / min, the stirring time is 30s, and the stirring temperature is room temperature; in step 4, the stirring rate of low-speed stirring is 150r / min, the stirring time is 30s, and the stirring temperature is room temperature, the stirring rate of high-speed stirring is 300r / min, the stirring time is 60s, and the stirring temperature is room temperature, and the stirring rate of low-speed stirring is 150r / min, the stirring time is 30s, and the stirring temperature is room temperature.

[0071] The stirring process of the phosphogypsum slope substrate in the above three embodiments is shown in the following figure. Figure 2 The photos of the specimen curing process are shown in Figure 3As shown. The comprehensive performance and shear strength tests were conducted on the phosphogypsum slope substrates prepared in the above three embodiments, and the test environment, test equipment, test conditions and sample size were the same. According to the test methods and test instruments in the "Soil Agrochemical Analysis Manual", the physical index test, chemical index test and pH value test of the slope substrate were conducted, and the test results are shown in Tables 1 and 2; according to the "Method for Determination of Fluidity of Cement Mortar" (GB / T2419-2005), the fluidity of the slope substrate was tested, and the test results are shown in Table 3.

[0072] Table 1 Test results of physical indexes of phosphogypsum slope substrate

[0073] Example <![CDATA[Bulk density (g / cm 3 )]]> Field water holding capacity (%) Capillary water retention (%) Effective water (%) Porosity(%) Embodiment 1 1.341 23.15 25.41 19.022 43.01 Embodiment 2 1.399 22.53 28.64 19.001 46.98 Embodiment 3 1.363 24.81 26.03 18.525 45.23

[0074] Table 2 Chemical indexes and pH test results of phosphogypsum slope substrate

[0075]

[0076] Table 3 Fluidity test results of phosphogypsum slope substrate

[0077] Example Fluidity(cm) Embodiment 1 25.9 Embodiment 2 25.4 Embodiment 3 26.3

[0078] The fluidity test photos of the phosphogypsum slope substrate in the above three embodiments are as follows: Figure 4 As shown, where: (a) is a fluidity test photo of Example 1, (b) is a fluidity test photo of Example 2, and (c) is a fluidity test photo of Example 3.

[0079] The photos of the shear test process of the phosphogypsum slope substrate in the above three embodiments are as follows: Figure 5 As shown. The shear resistance of the slope base material is its core and most important mechanical property, which has a decisive influence on the stability and safety of the slope. The shear test of the above three embodiments was carried out using a ZJ strain-controlled direct shear apparatus (quadruple shear), and the specific operation method is as follows:

[0080] S1: Use a ring cutter to cut samples of the same volume and place them in the shear box respectively. Move the upper and lower boxes to completely overlap them, and then tighten the fixing pin. Place the permeable stone in the lower box and on the top of the sample respectively. With the flat edge of the ring cutter facing downward, slowly push it into the shear box and remove the ring cutter. Add the pressure cover plate and the pressure frame in sequence, and the pressure frame will apply vertical loads of 100kPa, 200kPa, 300kPa, and 400kPa.

[0081] S2: Slowly turn the knob until the long needle of the dial indicator on the force ring moves slightly. Be careful not to over-tighten it, otherwise it will cause incorrect readings in the formal test. Adjust the force ring reading to zero.

[0082] S3: Remove the fixing pin and automatically perform shearing operation on the specimen at a rate of 0.8mm / min. Read the data in the dial indicator every 0.5mm and stop reading when the dial indicator reading suddenly drops or stops increasing. If the reading is still increasing, stop recording when it reaches 11mm.

[0083] The cohesion and internal friction angle measured by the shear test are shown in Table 4. The shear resistance fitting curve of the phosphogypsum slope substrate is shown in Figure 6 As shown, R 2 is the goodness of fit.

[0084] Table 4 Shear performance test results of phosphogypsum slope substrate

[0085] Example Cohesion(kPa) Internal friction angle (°) Embodiment 1 62.89 27.21 Embodiment 2 64.52 27.32 Embodiment 3 60.86 27.08

[0086] The phosphogypsum slope substrate prepared in the above three embodiments was subjected to a vegetation test. A round plastic flower pot with a diameter of 13 cm, a bottom diameter of 10.5 cm, and a height of 8 cm was selected for the test. 500 g of the prepared slope substrate was poured into the flower pot, and 0.75 g (350 grains) of grass seeds were evenly sown on the surface. The grass seeds were ryegrass, and then 100 g of the slope substrate was evenly added on the surface again. For each embodiment, three parallel samples were set up, and the test items included plant emergence rate and plant growth height.

[0087] (1) Plant germination rate determination: From the date of sowing, the specific number of seedlings in each pot of grass seeds was continuously recorded within 14 days. The final germination rate was calculated as the percentage of the number of seeds that germinated normally on the 14th day to the total number of seeds. On this basis, the germination rate of each pot of grass seeds was counted, and the average value of the three parallel pots was taken as the representative value of the germination rate of this group of samples. The test results are shown in Table 5.

[0088] (2) Plant height measurement: Starting from the fifth day after sowing, the above-ground height of the plants was continuously observed and recorded for 28 consecutive days. The most vigorous plant was selected from each pot sample, and a vernier caliper was used to measure from the ground diameter of the plant to the top bud. The average value of the three parallel samples was taken as the representative value of the plant growth height on that day. The test results are shown in Table 6.

[0089] Table 5 Plant emergence rate test results of phosphogypsum slope substrate

[0090]

[0091] Table 6 Test results of plant growth height on phosphogypsum slope substrate (unit: cm)

[0092]

[0093]

[0094] In summary, it can be clearly seen from the above test data that the phosphogypsum slope substrates prepared in the three embodiments have good comprehensive physical and chemical properties, providing a good foundation for plant growth. While ensuring the plant growth effect, the slope substrate also has high shear strength and cohesion, achieving a performance balance design of the comprehensive performance and shear strength of the phosphogypsum slope substrate, which can not only meet the slope requirements, but also provide an excellent environment for plant growth, and at a low cost.

[0095] Special note: The technical solution of the present invention involves many parameters, and the synergistic effects between the various parameters need to be comprehensively considered to obtain the beneficial effects and significant progress of the present invention. Moreover, the value ranges of the various parameters in the technical solution are obtained after a large number of experiments. For each parameter and the combination of each parameter, the inventor has recorded a large amount of experimental data. Due to space limitations, the specific experimental data will not be disclosed here.

[0096] It is not difficult for those skilled in the art to understand that the phosphogypsum slope substrate with balanced comprehensive performance and shear strength and the preparation method thereof of the present invention include any combination of the invention content and specific implementation methods of the above-mentioned invention specification and the various parts shown in the drawings. Due to the limited space and to make the specification concise, the various schemes composed of these combinations are not described one by one. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A phosphogypsum slope substrate with balanced comprehensive performance and shear strength, characterized in that: The mass percentages of each substance in the phosphogypsum slope base material are as follows: 48-62wt% of excavated soil, 5-7wt% of recycled aggregate from construction waste, 8-23wt% of phosphogypsum, 0.3-0.5wt% of perlite, and 20-25wt% of water; the ratio of the mass of the phosphogypsum to the sum of the mass of the excavated soil, the recycled aggregate from construction waste, the phosphogypsum, and the perlite is 0.1-0.3:1; the mass percentages of each substance in the recycled aggregate from construction waste are as follows: 75-80wt% of recycled aggregate from low-brick-concrete construction waste, and 20-25wt% of recycled aggregate from high-brick-concrete construction waste.

2. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 1, characterized in that: The excavated soil is soil excavated by manual or mechanical excavation during road construction; the pH value of the excavated soil is less than 8, and each kilogram of the excavated soil contains no less than 7g of organic matter.

3. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 2, characterized in that: The excavated soil includes six particle sizes, and the mass percentage of each particle size in the excavated soil is: particle size 1.18-2mm accounts for 15-20wt%, particle size 0.6-1.18mm accounts for 16-21wt%, particle size 0.3-0.6mm accounts for 18-23wt%, particle size 0.15-0.3mm accounts for 17-22wt%, particle size 0.075-0.15mm accounts for 10-15wt%, and particle size 0-0.075mm accounts for 7-12wt%.

4. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 3, characterized in that: The low-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of concrete buildings, and its brick-concrete content is 10-30wt%; the high-brick-concrete construction waste recycled aggregate is construction waste generated by the demolition of brick-concrete buildings, and its brick-concrete content is 70-80wt%.

5. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 4, characterized in that: The low-brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size of the low-brick-concrete construction waste recycled aggregate is: particle size 1.18-2mm accounts for 10-15wt%, particle size 0.6-1.18mm accounts for 10-15wt%, particle size 0.3-0.6mm accounts for 15-20wt%, particle size 0.15-0.3mm accounts for 25-30wt%, particle size 0.075-0.15mm accounts for 25-30wt%, particle size 0-0.075mm accounts for 5-10wt%.

6. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 5, characterized in that: The high-density brick-concrete construction waste recycled aggregate includes six particle sizes, and the mass percentage of each particle size of the high-density brick-concrete construction waste recycled aggregate is as follows: particle size 1.18-2mm accounts for 10-15wt%, particle size 0.6-1.18mm accounts for 20-25wt%, particle size 0.3-0.6mm accounts for 20-25wt%, particle size 0.15-0.3mm accounts for 15-20wt%, particle size 0.075-0.15mm accounts for 15-20wt%, and particle size 0-0.075mm accounts for 10-15wt%.

7. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 6, characterized in that: The mass of calcium sulfate dihydrate contained in the phosphogypsum is 80-95wt%, and the pH value of the phosphogypsum is less than 7; the phosphogypsum includes a particle size of 5-50μm.

8. The phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 7, characterized in that: The particle size of the perlite is no more than 2 mm and the density is 2.3 g / cm 3 , the water absorption rate is 238%.

9. A method for preparing a phosphogypsum slope substrate with balanced comprehensive performance and shear strength, characterized in that: The method for preparing the phosphogypsum slope substrate having balanced comprehensive performance and shear strength according to any one of claims 1 to 8 comprises the following steps in chronological order: Step 1: According to the design requirements, weigh the excavated soil of various particle sizes, the recycled aggregate of low-density brick-concrete construction waste of various particle sizes, the recycled aggregate of high-density brick-concrete construction waste of various particle sizes, phosphogypsum, perlite and water for later use; Step 2: putting excavated soil of various particle sizes, low-brick-concrete construction waste recycled aggregate of various particle sizes, high-brick-concrete construction waste recycled aggregate of various particle sizes, and perlite into a mixer and stirring at a low speed to form a solid mixture; Step 3: Add water into the mixer and stir it with the solid mixture at a low speed to form a mixed slurry; Step 4: Add phosphogypsum into a mixer and stir it with the mixed slurry three times, in the order of low-speed stirring, high-speed stirring and low-speed stirring. After three stirrings, a phosphogypsum slope base material with balanced comprehensive performance and shear strength can be obtained.

10. The method for preparing the phosphogypsum slope substrate with balanced comprehensive performance and shear strength according to claim 9, characterized in that: In step 2, the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 1-2min, and the stirring temperature is room temperature; in step 3, the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 30-60s, and the stirring temperature is room temperature; in step 4, the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 30-60s, and the stirring temperature is room temperature, the stirring rate of high-speed stirring is 200-300r / min, the stirring time is 60-90s, and the stirring temperature is room temperature, and the stirring rate of low-speed stirring is 80-150r / min, the stirring time is 30-60s, and the stirring temperature is room temperature.

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