Coal gangue-based water-permeable high-strength sidewalk step and preparation method thereof

Abstract

This invention discloses a permeable high-strength sidewalk paving slab based on coal gangue. The paving slab is made from the following raw materials in parts by weight: 80-95 parts coal gangue aggregate and 5-20 parts polyurethane adhesive. The particle size of the coal gangue aggregate is 5mm-20mm, of which the weight percentage of particles smaller than 10mm is 30%-50%. Furthermore, this invention also discloses a method for preparing the sidewalk paving slab, which involves crushing, screening, washing, and drying the coal gangue, then loading it into a mold, vibrating to compact it, spraying with polyurethane adhesive, curing at room temperature, and then demolding. The coal gangue-based permeable high-strength sidewalk paving slab of this invention requires no sintering, has a simple process, is low-carbon and environmentally friendly, has a compressive strength of not less than 30MPa, a flexural strength of not less than 5MPa, and a porosity of 15%-25%. It combines high strength and high permeability, can absorb large quantities of coal gangue solid waste, and is suitable for municipal roads, squares, and landscape paving, offering good economic and environmental benefits.

Description

Technical Field

[0001] This invention belongs to the technical field of comprehensive utilization of coal gangue and new building materials, specifically relating to a coal gangue-based permeable high-strength pedestrian walkway and its preparation method. Background Technology

[0002] Coal gangue is a large-scale industrial solid waste generated during coal mining and washing. It has a huge emission volume, occupies a large amount of land due to long-term stockpiling, and causes multiple pollution to soil, water and air. The large-scale disposal and high-value utilization of coal gangue is an important direction for current green development and solid waste resource utilization.

[0003] Existing coal gangue building paving materials mostly adopt sintering technology or cement-based cementitious systems. Sintering requires high-temperature firing, which consumes a lot of energy and releases harmful gases and dust during the firing process, which does not meet the requirements of low carbon and environmental protection. Cement-based products have long molding cycles, are brittle, and it is difficult to balance strength and water permeability, which can easily lead to cracking and water permeability reduction.

[0004] Therefore, there is a need to provide a non-sintering, environmentally friendly, efficient, and high-strength coal gangue-based permeable step plate and its preparation method, in order to overcome the shortcomings of existing technologies. Summary of the Invention

[0005] The technical problem to be solved by this invention is to address the shortcomings of the prior art by providing a permeable, high-strength pedestrian walkway slab based on coal gangue. This walkway slab is made of coal gangue aggregate and polyurethane adhesive. The point contact between the particles of the coal gangue aggregate effectively ensures permeability. The polyurethane adhesive encapsulates the coal gangue aggregate and bonds it into shape, effectively ensuring structural strength. This solves the problems of existing technologies where coal gangue is difficult to utilize or requires high-temperature calcination during slab manufacturing.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is: a permeable high-strength pedestrian walkway tread based on coal gangue, characterized in that the pedestrian walkway tread is made of the following raw materials in parts by weight: 80 to 95 parts of coal gangue aggregate and 5 to 20 parts of polyurethane adhesive; the particle size of the coal gangue aggregate is 5 mm to 20 mm, wherein the weight percentage of particles with a particle size less than 10 mm is 30% to 50%.

[0007] This invention uses coal gangue aggregate and polyurethane adhesive to make pedestrian walkway pavers. The point contact between the coal gangue aggregate particles effectively ensures permeability. The polyurethane adhesive coats the coal gangue aggregate, bonding it into shape and effectively ensuring structural strength. Furthermore, by controlling the ratio of the two materials, the invention maximizes the consumption of environmentally unfriendly and difficult-to-dispose-of coal gangue while ensuring the structural strength and permeability of the pedestrian walkway pavers. It also prevents insufficient polyurethane adhesive, which would lead to ineffective bonding between coal gangue aggregate particles and a loose, easily damaged structure; conversely, it prevents excessive polyurethane adhesive, which would fill the gaps between coal gangue aggregate particles, resulting in poor permeability or even complete impermeability. This invention effectively ensures the flatness and permeability of pedestrian walkway paving stone boundaries by controlling the particle size of the coal gangue aggregate. Pedestrian walkway paving stone thickness is typically 60mm~100mm. If the aggregate diameter is greater than 20mm, it is difficult to effectively ensure the flatness of the pedestrian walkway paving stone boundaries. If the aggregate diameter is less than 5mm, the individual weight is small, and it is easy to fuse into the polyurethane adhesive during spraying, preventing point contact between coal gangue aggregate particles and thus hindering permeability. Furthermore, by controlling the proportion of various particle sizes in the coal gangue aggregate, point contact between coal gangue aggregate particles is ensured, guaranteeing permeability and avoiding the shortcomings of tightly packed particles in continuously graded coal gangue aggregate, which results in low permeability.

[0008] The aforementioned permeable high-strength pedestrian walkway paving based on coal gangue is characterized in that the polyurethane adhesive is a two-component polyurethane adhesive. Component A of the polyurethane adhesive is isocyanate, and component B is a mixture of polyether polyol, polyester polyol, and chain extender. The weight ratio of component A to component B is 1:1~3. The solid content of the polyurethane adhesive is not less than 95%, and the bonding strength is not less than 10 MPa. This invention uses a two-component polyurethane adhesive, which features high strength, fast curing, and good durability. This avoids the shortcomings of single-component polyurethane adhesives, which are typically flexible, have long curing times, relatively low strength after curing, and relatively poor durability. Furthermore, pedestrian walkway paving is usually manufactured indoors, with less environmental interference. To fully improve strength, durability, and production efficiency, a two-component polyurethane adhesive is selected. By controlling the composition and ratio of components A and B of the two-component polyurethane adhesive, the isocyanate and polyether polyol react fully, avoiding imbalances that could lead to some components A or B not participating in the reaction. This causes initial defects in the adhesive's consolidation. By controlling the solid content, the purity and quality of the two-component polyurethane adhesive are ensured, preventing poor-quality adhesives from degrading due to volatilization, which would affect structural strength and durability. This also effectively reduces the risk of harmful gas generation during the spraying process. By controlling the bonding strength, the structural strength of the sidewalk slab is ensured. Since the particles of coal gangue aggregate are in point contact, if the bonding strength is too low, the bonding effect will be poor, and the structure will be prone to failure under external loads during use. Therefore, the bonding strength is limited to not less than 10 MPa.

[0009] The aforementioned permeable high-strength pedestrian walkway slab based on coal gangue is characterized in that the moisture content of the coal gangue aggregate is no more than 3%. This invention controls the moisture content of the coal gangue aggregate to prevent it from affecting the adhesive performance of the polyurethane adhesive. This is because polyurethane adhesive reacts with water to form bubbles, which adhere to the surface of the coal gangue aggregate, making it difficult for the coal gangue aggregate and polyurethane adhesive to reliably bond, thus affecting the adhesive performance. Furthermore, the moisture content of naturally air-dried coal gangue aggregate can generally be controlled below 3%, which is sufficient for bonding. If the required moisture content is too high, auxiliary measures such as drying are necessary, which are energy-intensive and uneconomical.

[0010] In addition, the present invention also discloses a method for preparing a permeable high-strength pedestrian walkway slab based on coal gangue, characterized in that the method includes the following steps: Step 1: The coal gangue is crushed and screened sequentially to obtain coal gangue aggregate; Step 2: Wash and dry the coal gangue aggregate obtained in Step 1 in sequence to obtain coal gangue aggregate with low moisture content. Step 3: Load the low-moisture coal gangue aggregate obtained in Step 2 into the mold, vibrate to compact it, and then spray with polyurethane adhesive to obtain the pre-product. Step 4: After the pre-product obtained in Step 3 is cured at room temperature, it is demolded to obtain a permeable high-strength pedestrian walkway slab based on coal gangue.

[0011] This invention involves sequentially crushing and screening coal gangue to obtain coal gangue aggregate with the required particle size. Impurities are removed by washing, and the aggregate is dried to obtain coal gangue aggregate with the required moisture content. The coal gangue aggregate is then loaded into a mold and vibrated to compact it, overcoming friction and interlocking forces, resulting in relative sliding and rearrangement. Smaller coal gangue aggregate particles fill the voids formed by larger particles, significantly increasing the bulk density and thus improving the compressive and flexural strength of the pedestrian walkway slab. Polyurethane adhesive is then sprayed onto the coal gangue aggregate, which flows down the surface under gravity and cures, achieving bonding. Room temperature curing ensures complete curing of the polyurethane adhesive. Finally, demolding yields a coal gangue-based permeable high-strength pedestrian walkway slab.

[0012] The above method is characterized in that the process of loading the low-moisture coal gangue aggregate into the mold, vibrating and compacting it, and then spraying polyurethane adhesive in step three is carried out in layers. Specifically, the low-moisture coal gangue aggregate is loaded into the mold to form a layer with a thickness of 4cm to 6cm, then vibrated and compacted, and then sprayed with polyurethane adhesive. This process is repeated until the required thickness is achieved. In this invention, the thickness of the coal gangue-based permeable high-strength pedestrian walkway slab is 6cm to 10cm. Dividing the coal gangue aggregate into multiple layers facilitates the penetration of polyurethane adhesive, ensures the bonding effect, facilitates the preparation of a thicker pedestrian walkway slab, and improves its strength. Because the polyurethane adhesive has a high viscosity, if the layers are too thick, the bonding effect is poor, and it is easy to loosen and break. Therefore, the thickness is controlled to be 4cm to 6cm. In addition, the low-moisture coal gangue aggregate is loaded into one or more layers. When multiple layers are loaded, the sprayed polyurethane adhesive can initially solidify within 60 seconds, which does not affect the subsequent layer bonding work.

[0013] It should be noted that each layer of coal gangue aggregate and polyurethane adhesive is made from the following parts by weight: 80 to 95 parts coal gangue aggregate and 5 to 20 parts polyurethane adhesive, to ensure bonding effect and drainage performance.

[0014] The method described above is characterized in that the room temperature curing time in step four is 5 to 30 minutes. This invention ensures that the polyurethane adhesive is fully and completely cured by controlling the room temperature curing time, thereby achieving optimal strength.

[0015] The above method is characterized in that the compressive strength of the coal gangue-based permeable high-strength pedestrian walkway slab obtained in step four is not less than 30 MPa, the flexural strength is not less than 5 MPa, and the porosity is 15%~25%. The coal gangue-based permeable high-strength pedestrian walkway slab prepared by this invention has excellent performance.

[0016] Compared with the prior art, the present invention has the following advantages: 1. This invention uses coal gangue aggregate and polyurethane adhesive to make pedestrian walkway treads. The point contact between the particles of coal gangue aggregate effectively ensures water permeability. The polyurethane adhesive is used to wrap the coal gangue aggregate and bond it into shape, which effectively ensures structural strength. The non-sintering bonding molding method eliminates high-temperature baking and produces no waste gas or dust emissions. It has low energy consumption and is green and environmentally friendly.

[0017] 2. This invention uses coal gangue as the main raw material, which can dispose of solid waste in large quantities, resulting in significant economic and environmental benefits. It also has a high utilization rate of solid waste, realizing the high-value utilization of coal gangue solid waste.

[0018] 3. This invention overcomes the shortcomings of the prior art and provides a method for preparing a permeable high-strength pedestrian walkway slab based on coal gangue. It can be cured rapidly at room temperature, has a short molding cycle, is suitable for continuous industrial production, and has a simple and efficient process. It solves the technical problems of high energy consumption, high pollution, low strength, poor permeability, and slow molding of traditional processes.

[0019] 4. The coal gangue-based permeable high-strength sidewalk slab prepared by this invention has excellent permeability, reasonable aggregate gradation, and forms continuous and interconnected pores with a porosity of 15% to 25%, allowing for rapid drainage. It also has excellent mechanical properties, with a compressive strength of not less than 30 MPa and a flexural strength of not less than 5 MPa, meeting the heavy-duty paving requirements of sidewalks and squares. It is suitable for scenarios requiring permeable and high-strength paving materials, such as municipal roads, square paving, and landscaping.

[0020] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0021] Figure 1 This is a schematic diagram of the process of loading low-moisture coal gangue aggregate into a mold, vibrating to compact it, and then spraying polyurethane adhesive.

[0022] Explanation of reference numerals in the attached figures: Detailed Implementation

[0023] Figure 1 This is a schematic diagram illustrating the process of loading low-moisture coal gangue aggregate into a mold, vibrating to compact it, and then spraying it with polyurethane adhesive, according to the present invention. Figure 1 As can be seen from the diagram, the present invention mixes polyurethane adhesive component A and polyurethane adhesive component B by drawing them into a mixer, and then sprays them onto the coal gangue aggregate in the mold through a spray nozzle.

[0024] Example 1 This embodiment includes the following steps: Step 1: Crush and screen the coal gangue in sequence to obtain coal gangue aggregate with a particle size of 5mm~20mm, of which the weight percentage of particles with a particle size less than 10mm is 40%, and the remainder has a particle size greater than or equal to 10mm. Step 2: Wash and dry the coal gangue aggregate obtained in Step 1 in sequence to obtain coal gangue aggregate with low moisture content of no more than 3%. Step 3: The low-moisture coal gangue aggregate obtained in Step 2 is loaded into a mold to form a 4cm thick layer. After vibration compaction, polyurethane adhesive is sprayed on. Both layers are made from the following parts by weight: 90 parts coal gangue aggregate and 10 parts polyurethane adhesive, to obtain a pre-product. The polyurethane adhesive is a two-component polyurethane adhesive. Component A of the polyurethane adhesive is isocyanate, and component B is a mixture of polyether polyol, polyester polyol, and chain extender. The weight ratio of component A to component B is 1:2. The solid content of the polyurethane adhesive is not less than 95%, and the bonding strength is not less than 10MPa. Step 4: After curing the pre-product obtained in Step 3 at room temperature for 20 minutes, demold to obtain a permeable high-strength pedestrian walkway slab based on coal gangue.

[0025] Tests showed that the compressive strength of the coal gangue-based permeable high-strength pedestrian walkway slab was 32 MPa, the flexural strength was 5.5 MPa, and the porosity was 20%.

[0026] Example 2 This embodiment includes the following steps: Step 1: Crush and screen the coal gangue in sequence to obtain coal gangue aggregate with a particle size of 5mm~20mm, of which the weight percentage of particles with a particle size less than 10mm is 30%, and the remainder has a particle size greater than or equal to 10mm. Step 2: Wash and dry the coal gangue aggregate obtained in Step 1 in sequence to obtain coal gangue aggregate with low moisture content of no more than 3%. Step 3: The low-moisture coal gangue aggregate obtained in Step 2 is loaded into a mold to form a 5cm thick layer. After vibration compaction, polyurethane adhesive is sprayed on. Both layers are made from the following parts by weight: 85 parts coal gangue aggregate and 15 parts polyurethane adhesive, yielding a pre-product. The polyurethane adhesive is a two-component adhesive. Component A is isocyanate, and component B is a mixture of polyether polyol, polyester polyol, and chain extender. The weight ratio of component A to component B is 1:1. The solid content of the polyurethane adhesive is not less than 95%, and the bonding strength is not less than 10MPa. Step 4: After curing the pre-product obtained in Step 3 at room temperature for 30 minutes, demold to obtain a permeable high-strength pedestrian walkway slab based on coal gangue.

[0027] Tests showed that the compressive strength of the coal gangue-based permeable high-strength pedestrian walkway slab is 35 MPa, the flexural strength is 6.0 MPa, and the porosity is 23%.

[0028] Example 3 This embodiment includes the following steps: Step 1: Crush and screen the coal gangue in sequence to obtain coal gangue aggregate with a particle size of 5mm~20mm, of which the weight percentage of particles with a particle size less than 10mm is 50%, and the remainder has a particle size greater than or equal to 10mm. Step 2: Wash and dry the coal gangue aggregate obtained in Step 1 in sequence to obtain coal gangue aggregate with low moisture content of no more than 3%. Step 3: The low-moisture coal gangue aggregate obtained in Step 2 is loaded into a mold to form a 6cm thick layer. After vibration compaction, polyurethane adhesive is sprayed on. Both layers are made from the following raw materials in parts by weight: 90 parts coal gangue aggregate and 10 parts polyurethane adhesive, to obtain a pre-product. The polyurethane adhesive is a two-component polyurethane adhesive. Component A of the polyurethane adhesive is isocyanate, and component B of the polyurethane adhesive is a mixture of polyether polyol, polyester polyol, and chain extender. The weight ratio of component A to component B of the polyurethane adhesive is 1:3. The solid content of the polyurethane adhesive is not less than 95%, and the bonding strength is not less than 10MPa. Step 4: After curing the pre-product obtained in Step 3 at room temperature for 5 minutes, demold to obtain a permeable high-strength pedestrian walkway slab based on coal gangue.

[0029] Tests showed that the compressive strength of the coal gangue-based permeable high-strength pedestrian walkway slab is 30 MPa, the flexural strength is 5.0 MPa, and the porosity is 18%.

[0030] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention in any way. Any simple modifications, alterations, and equivalent changes made to the above embodiments based on the inventive essence shall still fall within the protection scope of the present invention.

Claims

1. A permeable, high-strength pedestrian walkway paving material based on coal gangue, characterized in that, The pedestrian walkway tread is made from the following raw materials in parts by weight: 80 to 95 parts coal gangue aggregate and 5 to 20 parts polyurethane adhesive; the particle size of the coal gangue aggregate is 5 mm to 20 mm, of which the weight percentage of particles with a particle size less than 10 mm is 30% to 50%.

2. The permeable high-strength pedestrian walkway paving material based on coal gangue according to claim 1, characterized in that, The polyurethane adhesive is a two-component polyurethane adhesive. Component A of the polyurethane adhesive is isocyanate, and component B of the polyurethane adhesive is a mixture of polyether polyol, polyester polyol and chain extender. The weight ratio of component A to component B of the polyurethane adhesive is 1:1~3. The solid content of the polyurethane adhesive is not less than 95%, and the bonding strength is not less than 10 MPa.

3. The permeable high-strength pedestrian walkway paving material based on coal gangue according to claim 1, characterized in that, The moisture content of the coal gangue aggregate is no more than 3%.

4. A method for preparing a coal gangue-based permeable high-strength pedestrian walkway slab as described in any one of claims 1 to 3, characterized in that, The method includes the following steps: Step 1: The coal gangue is crushed and screened sequentially to obtain coal gangue aggregate; Step 2: Wash and dry the coal gangue aggregate obtained in Step 1 in sequence to obtain coal gangue aggregate with low moisture content. Step 3: Load the low-moisture coal gangue aggregate obtained in Step 2 into the mold, vibrate to compact it, and then spray with polyurethane adhesive to obtain the pre-product. Step 4: After the pre-product obtained in Step 3 is cured at room temperature, it is demolded to obtain a permeable high-strength pedestrian walkway slab based on coal gangue.

5. The method according to claim 4, characterized in that, The process described in step three, where low-moisture coal gangue aggregate is loaded into a mold, vibrated to compact it, and then sprayed with polyurethane adhesive, is carried out in layers. Specifically, the low-moisture coal gangue aggregate is loaded into the mold to form a layer with a thickness of 4cm to 6cm, then vibrated to compact it, and then sprayed with polyurethane adhesive. The above process is repeated until the required thickness is achieved.

6. The method according to claim 4, characterized in that, The curing time at room temperature in step four is 5 to 30 minutes.

7. The method according to claim 4, characterized in that, The compressive strength of the coal gangue-based permeable high-strength pedestrian walkway slab obtained in step four is not less than 30 MPa, the flexural strength is not less than 5 MPa, and the porosity is 15%~25%.

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