Solid waste-based binding material coal gangue vegetation concrete and preparation method thereof

Abstract

The invention provides solid-waste-based cementing material coal gangue vegetation concrete and a preparation method thereof. The solid-waste-based cementing material coal gangue vegetation concrete is prepared from the following raw materials: coal gangue aggregate, a solid-waste-based cementing material, tap water, water glass, KNO3 and polyvinyl alcohol building rubber powder. The coal gangue aggregate is used as a structural framework, the coal gangue powder, the mineral powder and the fly ash are used as cementing materials, and the low-alkali equivalent water glass is used as an alkali component, so that the strength requirement is met, and the pH is reduced. A proper amount of KNO3 and polyvinyl alcohol building rubber powder are doped, so that the workability of the slurry is improved, and meanwhile, the slurry has relatively high water permeability and mechanical property. According to the coal gangue vegetation concrete, solid waste materials can be fully utilized, particularly, coal gangue can be efficiently utilized, and the vegetation performance requirements can be met through a high-porosity different-aperture gradient permeation structure and low alkalinity of the coal gangue vegetation concrete. The method is suitable for greening laying of road slopes, river channel protection slopes, squares and parking lots and mine slopes, the slope surfaces can be reinforced, water and soil loss can be prevented, air can be purified, the ecological environment of a mining area can be repaired, and ecological balance can be maintained.

Description

Technical Field

[0001] The present invention belongs to the technical field of green building materials, and in particular relates to a solid waste-based cementitious material, coal gangue vegetation concrete, and a preparation method thereof. Background Art

[0002] Large-scale mining of gangue raises concerns about land occupation, environmental pollution, and safety risks. Currently, a small amount of gangue is used to produce high-value-added products such as silica, molecular sieves, kaolin, and catalysts. However, these production methods place high demands on the gangue's mineral composition, purity, and stability, hindering its efficient and large-scale utilization. Gangue is widely used in building materials, such as gangue bricks, gangue aggregate concrete, and road base layers. Using gangue as a substitute for clay in brickmaking effectively curbs the loss of arable land resources and enables large-scale utilization of gangue. However, due to the significant differences in its mineral composition, controlling the homogeneity of the raw materials during brickmaking presents a technical challenge, requiring complex pretreatment processes and formulation adjustments. The use of gangue in concrete can reduce reliance on natural sand and gravel. However, the sulfides, active silica, and unburned carbon in gangue, as well as the porosity and flaky structure of the aggregate, can lead to poor concrete mechanical properties and durability. Although gangue has been used in building materials to some extent, its overall utilization rate remains low due to these technical bottlenecks.

[0003] Vegetative concrete is a new type of concrete material that combines engineering protection with ecological restoration. Vegetative concrete combines coarse aggregate with cementitious materials to form a porous structure similar to shachima, combining mechanical properties with plant growth properties. Vegetative concrete has a multi-level permeability gradient of micropores and macropores, which reduces rainwater runoff, forms an internal rainwater circulation system, and provides a water supply environment for plant roots. Currently, the preparation of vegetative concrete mainly utilizes natural aggregates and ordinary Portland cement. However, the excessive exploitation of natural aggregates has caused serious ecological damage, and the production of ordinary Portland cement is extremely environmentally unfriendly. Furthermore, the alkalinity of ordinary Portland cement during hydration is too high, which is not conducive to the normal growth of plants, and the addition of admixtures increases costs. At the same time, due to the limited density of natural aggregates, vegetative concrete has difficulty effectively retaining moisture to meet the growth needs of plants. Summary of the Invention

[0004] To overcome the shortcomings of the prior art, the present invention aims to provide a solid waste-based cementitious material, coal gangue bio-concrete, and its preparation method, while also realizing the resourceful utilization of coal gangue. By leveraging the strength, moisture retention, and low alkalinity of coal gangue, it achieves efficient compatibility with bio-concrete, effectively alleviating the shortage of natural resources.

[0005] In order to achieve the above object, the technical solution adopted by the present invention is:

[0006] A solid waste-based cementitious material coal gangue vegetation concrete, whose raw materials are composed of: solid waste-based cementitious material, coal gangue aggregate, water and additives. By weight, the components of the solid waste-based cementitious material are: 30% to 40% coal gangue powder, 30% to 40% mineral powder, and 20% to 40% fly ash; based on the weight of the solid waste-based cementitious material, the additives include: water glass with an alkali equivalent of 3% to 4%, 2% to 4% KNO3, and 0.6% to 0.8% polyvinyl alcohol building glue powder.

[0007] In one embodiment, the gangue aggregate has a particle size of 10-20 mm, and the gangue powder is a finely ground product of the gangue, with a 45 μm square mesh sieve residue of no more than 30%. Gangue aggregate within this particle size range can provide the bioremediation concrete with a suitable pore size composition, improving mechanical properties and water permeability. Finely ground gangue powder is inexpensive and more easily stimulates its gelling activity.

[0008] In one embodiment, the modulus of the water glass is 1.5 to 1.8, and the concentration is 28 to 32%. Under these parameters, the alkalinity of the water glass can more effectively stimulate the gelling activity of solid waste, and is also easier to store and prevent crystallization.

[0009] In one embodiment, the mineral powder is S95 grade granulated blast furnace slag powder discharged from blast furnace ironmaking. Under this parameter, the mineral powder activity index is greater than 95%, and has relatively good mechanical properties.

[0010] In one embodiment, the fly ash is Class II ash, wherein the fly ash has a 45 μm square hole sieve residue of no more than 30% and an activity index of more than 70%.

[0011] In one embodiment, the polyvinyl alcohol construction adhesive powder is a cold water instant type, which can increase the viscosity of the slurry and adjust its fluidity.

[0012] In one embodiment, the concrete has a binder-to-cement ratio of 0.20 to 0.24, a water-to-binder ratio of 0.32 to 0.36, and mixing water includes water introduced by a water glass solution. With these parameters, the bioremediation concrete exhibits excellent mechanical and water permeability properties and a high interconnected porosity.

[0013] The present invention also provides a method for preparing the solid waste-based cementitious material coal gangue vegetation concrete, comprising the following steps:

[0014] Step 1: According to the mass fraction requirements of each raw material, coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder are weighed, put into a blender and stirred evenly to obtain a mixed dry material;

[0015] Step 2: Add the weighed water glass solution to the mixing water, mix well, then add it to the mixed dry materials in step 1 and continue stirring;

[0016] Step 3: Pour the weighed coal gangue aggregate into the mixed slurry of step 2, stir evenly, then cast and shape, and perform moisturizing and curing to obtain the coal gangue vegetation concrete.

[0017] In one embodiment, the mixer is a horizontal mixer.

[0018] In one embodiment, in step 1, the stirring time is 10 to 20 seconds and the stirring rate is 40 r / min to obtain a mixed dry material; in step 2, the stirring time is 30 to 40 seconds and the stirring rate is 40 r / min; in step 3, the stirring time is 100 to 120 seconds and the stirring rate is 40 r / min.

[0019] The coal gangue vegetated concrete of this invention boasts high strength and permeability, and its high porosity and low alkalinity meet the growing requirements of most plants. It is suitable for reinforcing slope structures such as highway slopes, river bank protection, and mine slopes. It can prevent soil erosion, purify the air, and is of great significance to ecological restoration. It is also suitable for greening flat structures such as plazas and parking lots.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The gangue aggregate used in the present invention is crushed solid waste generated during coal mining and washing. It has high hardness and a porous structure. It can replace natural aggregate in bioremediation concrete and has good mechanical properties and water permeability. At the same time, the gangue bioremediation concrete has a multi-level permeability gradient of micropores and macropores, which can retain moisture and reduce evaporation rate, forming an internal circulation system for rainwater.

[0022] (2) The cementitious materials used in the present invention are all industrial solid waste, mainly coal gangue powder, granulated blast furnace slag powder, and fly ash. By activating industrial solid waste with alkali, it is given cementitious activity and can replace cement, thereby reducing the land occupation and environmental pollution caused by solid waste storage, achieving full utilization of industrial waste, and conforming to the concept of sustainable development.

[0023] (3) The gangue powder and gangue aggregates used in the present invention contain trace amounts of humus, which provide plants with nutrients such as nitrogen, phosphorus, potassium, iron, manganese, and zinc, providing the necessary nutritional support for plant growth. Gangue also has unique slow-release nutrient properties, which can achieve a continuous supply of nutrients, ensuring the nutritional needs of plants at different growth stages and avoiding environmental pollution caused by nutrient loss.

[0024] (4) The present invention utilizes low-alkali modulus water glass as an activator, fully stimulating the potential activity of fly ash, mineral powder, and coal gangue powder. The low alkalinity of the cementitious material and the slow water release mechanism of the coal gangue aggregate can significantly reduce the alkalinity of the vegetative concrete, providing a suitable environment for plant growth.

[0025] (5) The addition of inorganic salt KNO3 in the present invention can improve the workability of the slurry, and the NO3 released by it - and K + It can be directly absorbed by plant roots. The water absorption and water retention of coal gangue vegetation concrete can maintain the relative humidity inside it, and synergistically with the nitrogen and potassium release function of KNO3 to form a "water-nutrient" dual slow-release system, providing the necessary conditions for plant growth.

[0026] The present invention also provides a process for preparing coal gangue-based concrete using solid waste-based cementitious materials. The process involves uniformly mixing coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder. Mixing water and a water glass solution are then added to the dry materials and stirred evenly. The coal gangue aggregate is then added to the slurry, stirred evenly, poured into the slurry, and then covered and cured. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 The present invention is a flow chart of the preparation process of coal gangue vegetation concrete, a solid waste-based cementitious material. DETAILED DESCRIPTION

[0028] In order to make the technical problems, technical solutions and beneficial effects solved by the present invention more clearly understood, the present invention is further described in detail in the following specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0029] As mentioned above, existing bio-concrete relies primarily on natural aggregates. Mining rock causes severe environmental damage and is costly. Furthermore, coal mining leads to massive accumulation of gangue, severely damaging the ecology of mining areas.

[0030] The present invention uses crushed coal gangue aggregate as the structural skeleton, coal gangue powder, mineral powder, and fly ash as the cementitious materials, and low-alkali equivalent water glass solution as the alkaline component, which meets the strength requirements and reduces the pH. In addition, the water glass can fully stimulate the potential activity of mineral powder and coal gangue powder. The inorganic salt KNO3 and polyvinyl alcohol building glue powder improve the workability of the slurry while having high permeability and mechanical properties, can optimize the pore structure of the vegetation concrete, and improve its cohesiveness. The NO3 released by the inorganic salt KNO3 - and K +It can be directly absorbed by plant roots, meeting the growth needs of most plants. At the same time, coal gangue completely replaces natural aggregates, making full use of solid waste materials. In particular, it can improve the utilization rate of coal gangue and reduce the accumulation of coal gangue in mining areas, which has environmental and economic benefits. The high porosity, different pore size gradient permeability structure and low alkalinity of coal gangue aggregate can meet the requirements of vegetation performance. This coal gangue vegetation concrete is used in river bank protection, green paving of squares and parking lots, and mine slopes. It can reinforce slopes to prevent soil erosion, purify the air, repair the ecological environment of mining areas, maintain ecological balance, and is of great significance to ecological restoration.

[0031] Therefore, the raw material composition of the coal gangue vegetation concrete of the solid waste-based cementitious material described in the present invention is:

[0032] Gangue aggregate, gangue powder, mineral powder, fly ash, tap water, 3-4% water glass with an alkali equivalent of 2-4% KNO3 and 0.6-0.8% polyvinyl alcohol building adhesive powder based on the mass of the cementitious material; and the cementitious material composition by mass is 30-40% gangue powder, 30-40% mineral powder and 20-40% fly ash; wherein the water-binder ratio is 0.32-0.36, and the binder-binder ratio is 0.2-0.24, where the water-binder ratio is the mass ratio of mixing water to cementitious material, and the binder-binder ratio is the mass ratio of cementitious material to aggregate.

[0033] Gangue aggregate and gangue powder are made by crushing and grinding gangue. The ore powder is S95-grade granulated blast furnace slag powder discharged from blast furnace ironmaking, and the fly ash is Class II ash. The polyvinyl alcohol building adhesive powder is cold-water instant. The modulus of the water glass solution is 1.5-1.8.

[0034] As attached Figure 1 As shown, the present invention also provides a method for preparing the coal gangue vegetation concrete, comprising the following steps:

[0035] Step 1: According to the mass fraction requirements of each raw material, coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder are weighed and put into a blender to obtain a mixed dry material; for example, the blender can be a horizontal blender, the stirring time can be 10 to 20 seconds, and the stirring blade speed is 40 r / min.

[0036] Step 2: Add the weighed mixing water to the water glass solution, mix well, and then add it to the mixed dry materials in step 1, and continue stirring evenly; for example, the stirring time is 30 to 40 seconds, and the stirring blade speed is 40 r / min.

[0037] Step 3: Pour the weighed gangue aggregate into a mixer and mix thoroughly. Then, cast and cure to obtain the gangue vegetation concrete. For example, the mixing time is 100-120 seconds, and the stirring blade speed is 40 rpm.

[0038] The following are several embodiments of the present invention.

[0039] Example 1

[0040] The raw materials of a solid waste-based cementitious material coal gangue vegetation concrete include:

[0041] Gangue aggregate: 1400kg

[0042] Gangue powder: 84kg

[0043] Granulated blast furnace slag powder: 84kg;

[0044] Fly ash: 112kg

[0045] Water glass: 73.5kg;

[0046] KNO3: 8.4kg;

[0047] Polyvinyl alcohol building glue powder: 1.68kg;

[0048] Water: 42.2kg.

[0049] Among them, the glue-bone ratio is 0.2, the water-binder ratio is 0.34, the alkali equivalent is 3%, the water glass modulus is 1.5, and the concentration is 28%.

[0050] Step 1: According to the mass fraction requirements of each raw material, coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder are weighed and put into a blender to stir to obtain a mixed dry material; wherein, the stirring time can be 10s, and the stirring blade speed is 40r / min.

[0051] Step 2: Add the weighed mixing water to the water glass solution, mix, and then add to the mixed dry materials in step 1, and continue stirring evenly; wherein, the stirring time is 40s, and the stirring blade speed is 40r / min.

[0052] Step 3: Pour the weighed gangue aggregate into a mixer, mix it evenly, then cast it into shape and cure it to obtain the gangue vegetation concrete. The mixing time is 110 seconds and the stirring blade speed is 40 r / min.

[0053] Using the coal gangue vegetation concrete described in Example 1, the 7-day compressive strength is 7.3 MPa, the 28-day compressive strength is 10.4 MPa; the permeability coefficient is 9.36 mm / s; the 28-day pore pH is 9.3; the connected porosity is 26.8%; the strength loss after 25 freeze-thaw cycles is 10.1%; the coverage rate of Elymus salsa after 42 days of planting is 82%, the plant height is 17 cm, and the root length is 6 cm.

[0054] Example 2

[0055] The raw materials of a solid waste-based cementitious material coal gangue vegetation concrete include:

[0056] Gangue aggregate: 1400kg

[0057] Gangue powder: 123.2kg

[0058] Granulated blast furnace slag powder: 123.2kg;

[0059] Fly ash: 61.6kg

[0060] Water glass: 105.6kg;

[0061] KNO3: 12.32kg;

[0062] Polyvinyl alcohol building glue powder: 2.16kg;

[0063] Water: 45.2kg.

[0064] Among them, the glue-bone ratio is 0.22, the water-binder ratio is 0.35, the alkali equivalent is 4%, the water glass modulus is 1.8, and the concentration is 32%.

[0065] Step 1: According to the mass fraction requirements of each raw material, coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder are weighed and put into a blender to stir to obtain a mixed dry material; wherein, the stirring time can be 20s, and the stirring blade speed is 40r / min.

[0066] Step 2: Add the weighed mixing water to the water glass solution, mix, and then add to the mixed dry materials in step 1, and continue stirring evenly; wherein, the stirring time is 30s, and the stirring blade speed is 40r / min.

[0067] Step 3: Pour the weighed gangue aggregate into a mixer, stir evenly, then cast and shape, and cure to obtain the gangue vegetation concrete. The stirring time is 100 seconds, and the stirring blade speed is 40 r / min.

[0068] When the coal gangue vegetation concrete described in Example 2 was used, its performance was tested, and the test results were as follows: the 7d compressive strength was 6.8 MPa, the 28d compressive strength was 10.9 MPa; the permeability coefficient was 10.12 mm / s; the 28d pore pH was 9.6; the connected porosity was 25.4%; the strength loss after 25 freeze-thaw cycles was 10.9%; the coverage rate of Elymus salsa after 42 days of planting was 86%, the plant height was 11 cm, and the root length was 5.5 cm.

[0069] Example 3

[0070] The raw materials of a solid waste-based cementitious material coal gangue vegetation concrete include:

[0071] Gangue aggregate: 1400kg

[0072] Gangue powder: 117.6

[0073] Granulated blast furnace slag powder: 117.6kg;

[0074] Fly ash: 100.8kg

[0075] Water glass: 103.7kg;

[0076] KNO3: 13.44kg;

[0077] Polyvinyl alcohol building glue powder: 2.69kg;

[0078] Water: 48.4kg.

[0079] Among them, the glue-binder ratio is 0.24, the water-binder ratio is 0.36, the alkali equivalent is 3.5%, the water glass modulus is 1.7, and the concentration is 30%.

[0080] Step 1: According to the mass fraction requirements of each raw material, coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder are weighed and put into a blender to stir to obtain a mixed dry material; wherein, the stirring time can be 15s, and the stirring blade speed is 40r / min.

[0081] Step 2: Add the weighed mixing water to the water glass solution, mix, and then add to the mixed dry materials in step 1, and continue stirring evenly; wherein, the stirring time is 35 seconds, and the stirring blade speed is 40 r / min.

[0082] Step 3: Pour the weighed coal gangue aggregate into a mixer, stir evenly, then cast and shape it, and cure it to obtain the coal gangue vegetation concrete. The stirring time is 120 seconds, and the stirring blade speed is 40 r / min.

[0083] When the coal gangue vegetation concrete described in Example 3 was used, its performance was tested, and the test results were as follows: the 7d compressive strength was 7.3 MPa, the 28d compressive strength was 11.2 MPa; the permeability coefficient was 9.25 mm / s; the 28d pore pH was 10.0; the connected porosity was 24.8%; the strength loss after 25 freeze-thaw cycles was 8.5%; the coverage rate of Elymus salsa after 42 days of planting was 80%, the plant height was 14 cm, and the root length was 7.5 cm.

Claims

1. A solid waste-based cementitious material coal gangue vegetation concrete, whose raw materials are composed of: solid waste-based cementitious material, coal gangue aggregate, water and additives, characterized in that: By weight, the components of the solid waste-based cementitious material are: 30% to 40% coal gangue powder, 30% to 40% mineral powder, and 20% to 40% fly ash; by weight of the solid waste-based cementitious material, the additives include: water glass with an alkali equivalent of 3% to 4%, 2% to 4% KNO3, and 0.6% to 0.8% polyvinyl alcohol construction glue powder.

2. The solid waste-based cementitious material coal gangue vegetation concrete according to claim 1, characterized in that: The particle size of the coal gangue aggregate is 10-20 mm, and the coal gangue powder is a product of finely ground coal gangue, with the residue on a 45 μm square hole sieve not exceeding 30%.

3. The solid waste-based cementitious material coal gangue vegetation concrete according to claim 1, characterized in that: The modulus of the water glass is 1.5-1.8, and the concentration is 28-32%.

4. The solid waste-based cementitious material coal gangue vegetation concrete according to claim 1, characterized in that: The mineral powder is S95 grade granulated blast furnace slag powder discharged from blast furnace ironmaking, and the fly ash is grade II ash.

5. The solid waste-based cementitious material coal gangue vegetation concrete according to claim 1, characterized in that: The polyvinyl alcohol building glue powder is cold water instant soluble.

6. The solid waste-based cementitious material coal gangue vegetation concrete according to claim 1, characterized in that: The concrete has a binder-to-cement ratio of 0.20 to 0.24, a water-to-binder ratio of 0.32 to 0.36, and mixing water includes water brought in by water glass solution.

7. The method for preparing the solid waste-based cementitious material coal gangue vegetation concrete according to claims 1-6, characterized in that: The preparation method comprises the following steps: Step 1: According to the mass fraction requirements of each raw material, coal gangue powder, mineral powder, fly ash, KNO3, and polyvinyl alcohol building adhesive powder are weighed, put into a blender and stirred evenly to obtain a mixed dry material; Step 2: Add the weighed water glass solution to the mixing water, mix well, then add it to the mixed dry materials in step 1 and continue stirring; Step 3: Pour the weighed coal gangue aggregate into the mixed slurry of step 2, stir evenly, then cast and shape, and perform moisturizing and curing to obtain the coal gangue vegetation concrete.

8. The preparation method according to claim 7, characterized in that: In the step 1, the stirring time is 10 to 20 seconds and the stirring rate is 40 r / min to obtain a mixed dry material; in the step 2, the stirring time is 30 to 40 seconds and the stirring rate is 40 r / min; in the step 3, the stirring time is 100 to 120 seconds and the stirring rate is 40 r / min.

9. Application of the solid waste-based cementitious material coal gangue vegetation concrete according to claim 1 for slope reinforcement.

10. Use of the solid waste-based cementitious material coal gangue vegetation concrete according to claim 1 for paving square greening.

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