3D printing lightweight concrete prepared from modified foamed plastic particles and preparation method of 3D printing lightweight concrete
By modifying waste foam plastic particles, improving their surface properties, and combining them with other components, the problem of insufficient interfacial adhesion of waste foam plastic particles in 3D printed lightweight concrete was solved. This resulted in good mechanical properties and resource utilization, reduced costs, and environmental protection.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- KZJ NEW MATERIALS GROUP CO LTD
- Filing Date
- 2025-12-02
- Publication Date
- 2026-04-28
AI Technical Summary
Waste foamed plastic particles have insufficient interfacial adhesion due to their hydrophobicity in 3D printed lightweight concrete, which affects their mechanical properties and limits their application.
By modifying waste foam plastic particles, oxidants and surface modifier solutions are used to improve their surface properties, forming a hydrophilic surface. Combined with components such as desulfurized fly ash, mineral powder, fiber, and alkali activator, modified foam plastic particles are prepared to improve interfacial adhesion and mechanical properties.
It improves the resource utilization rate of waste foam plastic particles, reduces the cost of 3D printed lightweight concrete, enhances its fluidity, extrudability, constructability and compressive strength, and protects the environment.
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Abstract
Description
Technical Field
[0001] This application relates to the field of building materials technology, and in particular to a 3D-printed lightweight concrete made from modified foamed plastic particles and its preparation method. Background Technology
[0002] 3D printing of lightweight concrete, as an additive manufacturing technology, offers advantages such as faster production speed and reduced material consumption. Among its many advantages, the most significant is the wide availability of printing materials, which aligns well with the resource utilization of waste materials and conforms to the concept of green and environmentally friendly development.
[0003] Every year, a large amount of plastic products are discarded globally. Traditional plastic products are not biodegradable and cause environmental pollution, making recycling an inevitable trend in environmental development. For example, approximately 3 billion pairs of athletic shoes are discarded globally each year, with plastic soles accounting for over 50% of their weight. In China alone, over 200,000 tons of waste shoe sole materials are generated annually. Because traditional landfill and waste incineration are inefficient and polluting, recycling these waste plastic shoe soles has become an important issue in urban solid waste management.
[0004] Therefore, waste foam plastics can be recycled using 3D printing lightweight concrete technology. By using appropriate raw material ratios, waste foam plastics of different particle sizes can be used as aggregates or powdered fillers to prepare 3D printed lightweight concrete with lower density, higher chemical resistance, and better thermal insulation performance. However, due to the hydrophobic nature of waste foam plastic surfaces, insufficient interfacial adhesion can easily occur in concrete structures, significantly affecting the mechanical properties of the prepared 3D printed lightweight concrete and severely limiting the application of waste foam plastics as a raw material in 3D printed lightweight concrete.
[0005] In summary, improving the hydrophobicity of waste foam plastic particles is a key issue in addressing the decline in mechanical properties of 3D-printed lightweight concrete prepared from waste foam plastic particles. This application utilizes waste foam plastic resources in 3D-printed lightweight concrete, which can save costs and resources, protect the environment, and ensure that the resulting 3D-printed lightweight concrete possesses good mechanical properties—a problem that urgently needs to be solved in this industry. Summary of the Invention
[0006] To address the shortcomings of existing technologies mentioned in the background section, this application provides a method for preparing 3D-printed lightweight concrete using modified foamed plastic particles. By modifying waste foamed plastic particles, the resource utilization rate and performance of these particles can be improved, reducing the cost of 3D-printed lightweight concrete. This not only creates considerable economic benefits but also effectively reduces the environmental damage and pollution caused by waste foamed plastic particles. The technical solution is as follows: This application provides a 3D-printed lightweight concrete prepared from modified foamed plastic particles, comprising the following components: mineral powder, desulfurized fly ash, modified foamed plastic particles, fiber, alkali activator, defoamer, water-reducing agent, thickener, and water; wherein the modified foamed plastic particles are obtained by treating mixture A with a surface modifier solution; mixture A is obtained by immersing the foamed plastic particles in an oxidant solution at a temperature of 60-80°C.
[0007] In some embodiments, the preparation process of the modified foamed plastic particles is as follows: the foamed plastic particles and the oxidant solution are mixed and stirred at 60°C to 80°C for 1 to 4 hours, and dried to form the mixture A; a surface modifier solution is added to the mixture A, and after stirring for 2 to 6 hours, the solid and liquid are separated and the solid is dried to obtain the modified foamed plastic particles.
[0008] In some embodiments, the mass ratio of the foamed plastic particles to the oxidant solution is 1:(12-18); the mass ratio of the mixture A to the surface modifier solution is 1:(100-120).
[0009] In some embodiments, the oxidant is a mixture of potassium permanganate solution and sulfuric acid, wherein the weight ratio of potassium permanganate solution to sulfuric acid is 1:(0.5-1); the mass percentage concentration of potassium permanganate solute in the oxidant solution is 1.0%-4.0%; and the surface modifier solution is an aqueous solution of isocyanate-based silane coupling agent.
[0010] In some embodiments, the foamed plastic particles are waste foamed plastic particles, obtained by recycling and grinding plastic from waste foamed plastic products. Optionally, the waste foamed plastic products include waste foam shoe soles.
[0011] In some embodiments, the components of 3D printed lightweight concrete, by weight, include: 400-800 parts mineral powder, 100-400 parts desulfurized fly ash, 900-1500 parts modified foamed plastic particles, 5-11 parts fiber, 1-7 parts defoamer, 50-150 parts alkali activator, 3-11 parts water-reducing agent, 2-10 parts thickener, and 200-400 parts water.
[0012] In some embodiments, the components of 3D printed lightweight concrete, by weight, include: 500-700 parts mineral powder, 100-300 parts desulfurized fly ash, 1000-1300 parts modified foamed plastic particles, 6-10 parts fiber, 3-5 parts defoamer, 80-120 parts alkali activator, 4-10 parts water-reducing agent, 5-7 parts thickener, and 250-350 parts water.
[0013] In some embodiments, the mineral powder is S95 mineral powder, with a 28-day activity of 91-105% and a density of 2.93-2.99 g / cm³. 3 .
[0014] In some embodiments, the desulfurized fly ash has a fineness of 8-9% and a density of 2.14-2.34 g / cm³. 3 The activity is 65-75%; optionally, the desulfurized fly ash is a by-product of the desulfurization process in power plants, with a fineness of 8.5% and a density of 2.24 g / cm³. 3 , activity ≥70%.
[0015] In some embodiments, the fiber includes one or more combinations of polypropylene fiber, basalt fiber, and plant fiber.
[0016] In some embodiments, the alkaline activator includes one or more combinations of sodium silicate, sodium hydroxide, and magnesium oxide.
[0017] In some embodiments, the defoamer includes one or more combinations of ethane chloride, toluene, polysiloxane polyether, and polymeric propylene oxide.
[0018] In some embodiments, the water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of ≥30%.
[0019] In some embodiments, the thickener includes at least one of inorganic thickeners, lignocellulose thickeners, ether thickeners, and polyacrylate thickeners.
[0020] This application also provides a method for preparing 3D-printed lightweight concrete using modified foamed plastic particles as described above, which includes the following preparation steps: Weigh out the desulfurized fly ash and alkali activator, and mix them evenly to form the first mixture; Mineral powder, modified foamed plastic particles and fibers are added to the first mixture, and the mineral powder, modified foamed plastic particles and fibers are mixed evenly to obtain the second mixture; Add water to the second mixture and mix well to obtain a third mixture; Add defoamer, water-reducing agent and thickener to the third mixture, stir evenly, and obtain the 3D printed lightweight concrete.
[0021] Based on the above, compared with the prior art, the 3D-printed lightweight concrete prepared from modified foamed plastic particles provided in this application has the following beneficial effects: The proposed solution utilizes plastic waste and other recyclable materials in 3D-printed lightweight concrete, which can save costs and resources, protect the environment, and ensure that the resulting 3D-printed lightweight concrete has good fluidity, extrudability, constructability, as well as excellent compressive strength and modulus of elasticity.
[0022] Other features and beneficial effects of this application will be set forth in the following description and will be apparent in part from the description or may be learned by practicing the application. The purpose and other beneficial effects of this application can be realized and obtained from the description and claims. Detailed Implementation
[0023] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions in the embodiments of this application will be clearly and completely described below in conjunction with the embodiments of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. The technical features designed in the different implementations of this application described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.
[0024] In the description of this application, it should be noted that all terms used in this application (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this application pertains, and should not be construed as limiting this application; it should be further understood that the terms used in this application should be understood to have the same meaning as those in the context of this specification and the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this application.
[0025] This application provides a method for preparing 3D-printed lightweight concrete using modified waste foamed plastic particles, which includes the following preparation steps: (1) Weigh out the desulfurized fly ash and alkali activator, stir them evenly to form the first mixture, and let it stand for 0.5h to 1.5h after stirring; (2) Add mineral powder, modified waste foam plastic particles and fiber to the first mixture, and stir the mineral powder, modified waste foam plastic particles and fiber evenly to obtain the second mixture. The stirring time is 1 min to 4 min. (3) Add water to the second mixture and mix well to obtain a third mixture, with the ratio of the two being (6-15):(1-2); (4) Add defoamer, water-reducing agent and thickener to the third mixture, and mix evenly to obtain the 3D printed lightweight concrete prepared from modified waste foamed plastic particles. The mixtures are mixed by stirring for 3 min to 8 min at a speed of 1000 to 2000 rpm.
[0026] The concrete formula, by weight, comprises: 400-800 parts mineral powder, 100-400 parts desulfurized fly ash, 900-1500 parts modified waste foamed plastic granules, 5-11 parts fiber, 1-7 parts defoamer, 50-150 parts alkali activator, 3-11 parts water-reducing agent, 2-10 parts thickener, and 200-400 parts water.
[0027] Preferably, its components include: 500-700 parts of mineral powder, 100-300 parts of desulfurized fly ash, 1000-1300 parts of modified waste foamed plastic particles, 6-10 parts of fiber, 3-5 parts of defoamer, 80-120 parts of alkali activator, 4-10 parts of water-reducing agent, 5-7 parts of thickener, and 250-350 parts of water.
[0028] This application also provides a preferred embodiment of the method for preparing the modified foamed plastic particles, the specific steps of which are as follows: Waste old foam shoe soles are ground to obtain waste foam plastic granules, which are then soaked in an oxidant solution at a temperature of 60-80°C for 1-4 hours to obtain mixture A. A surface modifier solution is added to mixture A, and the mixture is stirred for 2-6 hours. The solid and liquid are then separated and the solid is dried to obtain the modified waste foam plastic granules.
[0029] The mass ratio of the waste foam plastic particles to the oxidant solution is 1:(12-18); the mass ratio of mixture A to the surface modifier solution is 1:(100-120). The oxidant is a mixture of potassium permanganate solution and sulfuric acid, with a weight ratio of 1:(0.5-1), and the mass percentage concentration of potassium permanganate solute in the oxidant solution is 1.0%-4.0%. The surface modifier solution is an aqueous solution of isocyanate-based silane coupling agent.
[0030] The raw material components are selected as follows: The mineral powder is S95 mineral powder, with a 28-day activity of 98% and a density of 2.96 g / cm³. 3 The desulfurized fly ash has a fineness of 8.5% and a density of 2.24 g / cm³. 3The activity is 70%; the fiber includes one or more combinations of polypropylene fiber, basalt fiber, and plant fiber; the alkali activator includes one or more combinations of sodium silicate, sodium hydroxide, and magnesium oxide; the defoamer includes one or more combinations of ethane chloride, toluene, polysiloxane polyether, and polymeric propylene oxide; the water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate ≥30%; the thickener includes at least one of inorganic thickener, lignocellulose thickener, ether thickener, and polyacrylate thickener.
[0031] This application also provides the following embodiments and comparative examples: This application also provides the formulations (unit: parts by weight) of the embodiments and comparative examples shown in Table 1: Table 1
[0032] The specific preparation processes for the embodiments and comparative examples are as follows: Example 1 The formula for 3D printed lightweight concrete is as follows: By weight, it comprises the following components: 600 parts mineral powder, 200 parts desulfurized fly ash, 900 parts modified waste foam plastic granules, 8 parts fiber, 4 parts defoamer, 100 parts alkali activator, 7 parts water-reducing agent, 6 parts thickener, and 300 parts water.
[0033] The mineral powder used was S95 mineral powder, with a 28-day activity of 98% and a density of 2.96 g / cm³. 3 The desulfurized fly ash used is a by-product of the power plant desulfurization process, with a fineness of 8.5%, a density of 2.24 g / cm3, and an activity of 70%. The fibers used include polypropylene fibers with a length of 6 mm. The alkali activator used is a mixture of sodium silicate and sodium hydroxide (mass ratio of 10:1). The defoamer used is a polysiloxane polyether defoamer. The water-reducing agent used is a polycarboxylate water-reducing agent with a water reduction rate of 35%. The thickener used is a lignocellulose thickener.
[0034] The preparation process of modified waste foamed plastic granules is as follows: Waste foam shoe soles are ground to obtain waste foam plastic granules. These granules are then soaked in an oxidant solution at 60°C for 4 hours to obtain mixture A. A surface modifier solution is then added to mixture A, and the mixture is stirred for 2 hours. The mixture is then filtered and dried at 90°C to obtain the modified waste foam plastic granules. The specific surface area of the obtained modified waste foam plastic granules is >300 m². 2 / kg, and its apparent density <1.25g / cm³ 3 .
[0035] The mass ratio of waste foam plastic particles to oxidant solution is 1:15, and the mass percentage concentration of potassium permanganate solute in the oxidant solution is 2.5%. The mass ratio of mixture A to surface modifier solution is 1:110. The oxidant is a mixture of potassium permanganate solution and sulfuric acid in a weight ratio of 1:1. The surface modifier solution is an aqueous solution of isocyanate-based silane coupling agent with a concentration of 1.2%.
[0036] The preparation process of 3D printed lightweight concrete is as follows: (1) Weigh out the desulfurized fly ash and alkali activator, stir them evenly to form the first mixture, and let it stand for 1 hour after stirring. (2) Add mineral powder, modified waste foam plastic particles and fiber to the first mixture, and stir the mineral powder, modified waste foam plastic particles and fiber evenly to obtain the second mixture. The stirring time is 2 min. (3) Add water to the second mixture and mix well to obtain a third mixture, with the ratio of the two being 10:1; (4) Add defoamer, water-reducing agent and thickener to the third mixture, and mix evenly to obtain the 3D printed lightweight concrete prepared from modified waste foamed plastic particles. The mixtures are mixed by stirring for 5 minutes at a speed of 1500 rpm.
[0037] Example 2 The formula for 3D printed lightweight concrete is as follows: By weight, it comprises the following components: 600 parts mineral powder, 200 parts desulfurized fly ash, 1200 parts modified waste foam plastic granules, 8 parts fiber, 4 parts defoamer, 100 parts alkali activator, 7 parts water-reducing agent, 6 parts thickener, and 300 parts water.
[0038] The mineral powder used was S95 mineral powder, with a 28-day activity of 98% and a density of 2.96 g / cm³. 3 The desulfurized fly ash used is a byproduct of the power plant's desulfurization process, with a fineness of 8.5% and a density of 2.24 g / cm³. 3 The activity is 70%; the fibers used include polypropylene fibers with a length of 6 mm; the alkali activator used is a mixture of sodium silicate and sodium hydroxide (mass ratio of 10:1); the defoamer used is a polysiloxane polyether defoamer; the water-reducing agent used is a polycarboxylate water-reducing agent with a water reduction rate of 35%; the thickener used is a lignocellulose thickener.
[0039] The preparation process of modified waste foamed plastic granules is as follows: Waste foam shoe soles are ground to obtain waste foam plastic granules. These granules are then soaked in an oxidant solution at 70°C for 2 hours to obtain mixture A. A surface modifier solution is added to mixture A, and the mixture is stirred for 4 hours. The mixture is then filtered and dried at 90°C to obtain the modified waste foam plastic granules. The specific surface area of the obtained modified waste foam plastic granules is >300 m². 2 / kg, and its apparent density <1.25g / cm³ 3 .
[0040] The mass ratio of waste foam plastic particles to the oxidant solution is 1:15, and the mass percentage concentration of potassium permanganate solute in the oxidant solution is 2.5%. The mass ratio of mixture A to the surface modifier solution is 1:110. The oxidant is a mixture of potassium permanganate solution and sulfuric acid in a weight ratio of 1:1. The surface modifier solution is an aqueous solution of isocyanate-based silane coupling agent with a concentration of 1.2%.
[0041] The preparation process of 3D printed lightweight concrete is as follows: (1) Weigh out the desulfurized fly ash and alkali activator, stir them evenly to form the first mixture, and let it stand for 1 hour after stirring. (2) Add mineral powder, modified waste foam plastic particles and fiber to the first mixture, and stir the mineral powder, modified waste foam plastic particles and fiber evenly to obtain the second mixture. The stirring time is 2 min. (3) Add water to the second mixture and mix well to obtain a third mixture, with the ratio of the two being 10:1; (4) Add defoamer, water-reducing agent and thickener to the third mixture, and mix evenly to obtain the 3D printed lightweight concrete prepared from modified waste foamed plastic particles. The mixtures are mixed by stirring for 5 minutes at a speed of 1500 rpm.
[0042] Example 3 The formula for 3D printed lightweight concrete is as follows: By weight, it comprises the following components: 600 parts mineral powder, 200 parts desulfurized fly ash, 1500 parts modified waste foam plastic granules, 8 parts fiber, 4 parts defoamer, 100 parts alkali activator, 7 parts water-reducing agent, 6 parts thickener, and 300 parts water.
[0043] The mineral powder used was S95 mineral powder, with a 28-day activity of 98% and a density of 2.96 g / cm³. 3 The desulfurized fly ash used is a byproduct of the power plant's desulfurization process, with a fineness of 8.5% and a density of 2.24 g / cm³. 3The activity is 70%; the fibers used include polypropylene fibers with a length of 6 mm; the alkali activator used is a mixture of sodium silicate and sodium hydroxide (mass ratio of 10:1); the defoamer used is a polysiloxane polyether defoamer; the water-reducing agent used is a polycarboxylate water-reducing agent with a water reduction rate of 35%; the thickener used is a lignocellulose thickener.
[0044] The preparation process of modified waste foamed plastic granules is as follows: Waste foam shoe soles are ground to obtain waste foam plastic granules, which are then soaked in an oxidant solution at 80°C for 1 hour to obtain mixture A. A surface modifier solution is added to mixture A, and after stirring for 6 hours, the mixture is filtered and dried at 90°C to obtain the modified waste foam plastic granules. The specific surface area of the obtained modified waste foam plastic granules is >300 m². 2 / kg, and its apparent density <1.25g / cm³ 3 .
[0045] The mass ratio of waste foam plastic particles to the oxidant solution is 1:15, and the mass percentage concentration of potassium permanganate solute in the oxidant solution is 2.5%. The mass ratio of mixture A to the surface modifier solution is 1:110. The oxidant is a mixture of potassium permanganate solution and sulfuric acid in a weight ratio of 1:1. The surface modifier solution is an aqueous solution of isocyanate-based silane coupling agent with a concentration of 1.2%.
[0046] The preparation process of 3D printed lightweight concrete is as follows: (1) Weigh out the desulfurized fly ash and alkali activator, stir them evenly to form the first mixture, and let it stand for 1 hour after stirring. (2) Add mineral powder, modified waste foam plastic particles and fiber to the first mixture, and stir the mineral powder, modified waste foam plastic particles and fiber evenly to obtain the second mixture. The stirring time is 2 min. (3) Add water to the second mixture and mix well to obtain a third mixture, with the ratio of the two being 10:1; (4) Add defoamer, water-reducing agent and thickener to the third mixture, and mix evenly to obtain the 3D printed lightweight concrete prepared from modified waste foamed plastic particles. The mixtures are mixed by stirring for 5 minutes at a speed of 1500 rpm.
[0047] Comparative Example 1 (the only difference from Example 2 is that unmodified waste foam plastic particles are used instead of modified waste foam plastic particles) Strictly following Example 2, 1200 parts of unmodified waste foam plastic particles were added to replace the modified waste foam plastic particles of Example 2 during the preparation of 3D printed lightweight concrete, and the results were used to compare the performance of the 3D printed lightweight concrete with those of Example 2.
[0048] The only difference between this comparative example and Example 2 is that the comparative example uses unmodified waste foam plastic particles, while the other formulations and preparation processes are the same as in Example 2.
[0049] Comparative Example 2 (the only difference from Example 2 is that ordinary plastic granules are used instead of modified waste foam plastic granules) In strict accordance with Example 2, 1200 parts of ordinary plastic particles were added to replace the modified waste foam plastic particles of Example 2 during the preparation of 3D printed lightweight concrete, and the results were used to compare the performance of the 3D printed lightweight concrete with those of Example 2.
[0050] The only difference between this comparative example and Example 2 is that an equal amount of ordinary plastic particles are added, while the other formulations and preparation processes are the same as in Example 2.
[0051] Comparative Example 3 (the only difference from Example 2 is that manufactured sand was used instead of modified waste foam plastic particles) In strict accordance with Example 2, 1200 parts of manufactured sand were added to replace the modified waste foam plastic particles of Example 2 during the preparation of 3D printed lightweight concrete, and the results were used to compare the performance of the 3D printed lightweight concrete with those of Example 2.
[0052] The only difference between this comparative example and Example 2 is that an equal amount of manufactured sand is added, while the other formulations and preparation processes are the same as in Example 2.
[0053] Comparative Example 4 (the only difference from Example 2 is that ceramsite was used instead of modified waste foam plastic particles) In strict accordance with Example 2, 1200 parts of ceramsite were added to replace the modified waste foam plastic particles of Example 2 during the preparation of 3D printed lightweight concrete, and the results were used to compare the performance of the 3D printed lightweight concrete with those of Example 2.
[0054] The only difference between this comparative example and Example 2 is that an equal amount of ceramsite is added, while the other formulations and preparation processes are the same as in Example 2.
[0055] Comparative Example 5 (the only difference from Example 2 is that the oxidant soaking step was omitted in the preparation process of the modified waste foam plastic particles) The only difference between this comparative example and Example 2 is that, in the preparation process of the modified waste foam plastic particles in this comparative example, the waste foam plastic particles are not soaked in an oxidant solution, but are directly treated with a silane coupling agent. The other formulations and preparation processes are the same as in Example 2.
[0056] Comparative Example 6 (the only difference from Example 2 is that the coupling agent treatment step was omitted in the preparation process of the modified waste foamed plastic particles) The only difference between this comparative example and Example 2 is that in the preparation process of the modified waste foam plastic particles in this comparative example, the waste foam plastic particles are soaked in an oxidant solution, then directly separated into solid and liquid and dried to obtain particles, without undergoing silane coupling agent treatment. The other formulations and preparation processes are the same as in Example 2.
[0057] Comparative Example 7 (the only difference from Example 2 is that the oxidant used in the preparation of the modified waste foamed plastic particles is different) The only difference between this comparative example and Example 2 is that the oxidant solution in this comparative example is a potassium permanganate solution (the same potassium permanganate solution used in the example). All other formulations and preparation processes are the same as in Example 2.
[0058] Comparative Example 8 (the only difference from Example 2 is that the oxidant used in the preparation of the modified waste foamed plastic particles is different) The only difference between this comparative example and Example 2 is that the oxidant solution in this comparative example is sulfuric acid (the same sulfuric acid used in the example). All other formulations and preparation processes are the same as in Example 2.
[0059] Comparative Example 9 (the only difference from Example 2 is that the oxidant used in the preparation of the modified waste foamed plastic particles is different) The only difference between this comparative example and Example 2 is that the oxidant solution in this comparative example is hydrogen peroxide. The other formulations and preparation processes are the same as in Example 2.
[0060] It should be noted that the potassium permanganate solution used in the examples and comparative examples has a mass percentage concentration of 5%, the sulfuric acid has a mass percentage concentration of 70%, and the hydrogen peroxide has a mass percentage concentration of 5%.
[0061] Performance tests were conducted on the finished products of the examples and comparative examples. The finished products obtained in the above embodiments and comparative examples were subjected to performance tests according to the standards "Technical Specification for 3D Printing of Concrete" T / CECS786-2020 and "Technical Specification for Application of Lightweight Aggregate Concrete" JGJ / T 12-2019. The test results are shown in Table 2. Table 2
[0062] Note: The modified waste foam plastic particle dosage is the percentage of modified waste foam plastic particles by weight in the total weight; 28d refers to the compressive strength of the concrete after 28 days of curing.
[0063] The test results in Table 2 show that: In the embodiments of this application, modified waste foam plastic particles are incorporated, which improves the compressive strength of the 3D printed lightweight concrete. The 3D printed lightweight concrete also has good fluidity, extrudability, constructability and other properties.
[0064] Comparing the data from Examples 1-3, it can be seen that as the amount of modified waste foam plastic particles increases, the fluidity of the 3D-printed lightweight concrete decreases, and its extrudability slightly declines. This may be because the modified waste foam plastic particles have increased water absorption; adding too much may cause the printed 3D-printed lightweight concrete to become thicker and drier, making it difficult to extrude from the printer nozzle, thus reducing its buildability and extrudability. Controlling the amount of modified waste foam plastic particles within the range defined in this application allows for the full application of these particles in 3D-printed lightweight concrete while ensuring that the 3D-printed lightweight concrete still possesses good fluidity, extrudability, buildability, and other properties, meeting the usage requirements.
[0065] The test results from Example 2 and Comparative Example 1 show that, compared to Example 2, the constructability of Comparative Example 1 is significantly worse, and its compressive strength is significantly reduced. The embodiments of this application use modified waste foam plastic particles, which have better interfacial adhesion to concrete than untreated waste foam plastic particles. The compressive strength of the hardened body after being incorporated into 3D printed lightweight concrete in equal amounts is 79.2% higher than that of the hardened body made from untreated waste foam plastic particles. This may be because the surface of the modified waste foam plastic particles is wettable, which can enhance the complexation of free Ca2+. + The ability of modified waste foam plastic particles to accelerate cement hydration and promote the deposition of hydration products on the surface of the modified waste foam plastic particles enhances the adhesion between the surface and the slurry, thereby enhancing the mechanical properties of 3D printed lightweight concrete. On the other hand, the fine modified waste foam plastic particles fill the voids inside the 3D printed lightweight concrete, making its internal structure more compact, which also improves the compressive strength of the 3D printed lightweight concrete.
[0066] The test results of Examples 1, 2, 3 and Comparative Example 2 show that the 3D printed lightweight concrete with modified waste foamed plastic particles has a lower bulk density and higher strength than the concrete with ordinary plastic particles. This may be because the density of foamed plastic particles is lower than that of ordinary plastic particles, and the poor adhesion between ordinary plastic particles and cement is the main reason for the serious decrease in concrete strength. However, the modified waste foamed plastic particles have successfully overcome this bottleneck through multiple chemical modification treatments, changing their hydrophobicity to hydrophilicity, thereby improving the compressive strength of the hardened body.
[0067] The test results of Example 2 and Comparative Example 3 show that, compared with Example 2, Comparative Example 3 has significantly better constructability. Furthermore, the 28-day compressive strength of Comparative Example 3 is not significantly different from that of Example 2, but its density far exceeds the requirements of the "Technical Specification for Application of Lightweight Aggregate Concrete" JGJ / T 12-2019 standard (≤1950 kg / m³). 3 ).
[0068] The test results of Example 2 and Comparative Example 4 show that the constructability and compressive strength of Comparative Example 4 are reduced compared to Example 2. This may be because the filling capacity of the ceramsite particles is not as good as that of the modified waste foam plastic particles, and the hydrophilic properties of the surface of the modified waste foam plastic particles are conducive to the hydration reaction, thereby promoting the development of the compressive strength of the hardened body.
[0069] The test results of Example 2 and Comparative Examples 5, 6, 7, 8 and 9 show that, compared with Example 2, the constructability and compressive strength of Comparative Examples 5, 6, 7, 8 and 9 are reduced. This may be because changing the modification method of waste foam plastic particles will reduce the modification effect, thus leading to a decrease in the performance of 3D printed lightweight concrete.
[0070] The 3D-printed lightweight concrete prepared from modified foamed plastic particles and its preparation method provided in this application include at least the following design concepts and beneficial effects: Design Concept (1) This application modifies waste foam plastic particles by adding an oxidant and a surface modifier solution. The solute in the surface modifier solution is adsorbed on the surface of the waste foam plastic particles, forming an organic molecular layer (organic functional groups such as amino and hydroxyl groups), thereby enhancing its hydrophilicity. This can enhance the complexation of free Ca 2+ This ability accelerates cement hydration, promotes the deposition of hydration products on the surface of modified waste foamed plastic particles, enhances the adhesion between the surface and the slurry, and thus enhances mechanical properties.
[0071] (2) By incorporating desulfurized fly ash and mineral powder, this application can replace all cement and be utilized in the form of alkali activation, playing the role of cementing material in 3D printed lightweight concrete. On the other hand, such a design can reduce the overall material cost.
[0072] (3) This application incorporates fiber, thickener, polycarboxylate superplasticizer and other components to work together. Among them, fiber (e.g. polypropylene fiber) can improve the crack resistance of 3D printed lightweight concrete; thickener can improve the bonding performance of 3D printed lightweight concrete; polycarboxylate superplasticizer can reduce the water consumption of 3D printed lightweight concrete and improve the fluidity and compressive strength of 3D printed lightweight concrete. Through the combination of these components, 3D printed lightweight concrete has excellent extrudability, constructability and other properties.
[0073] Beneficial effects (1) This application utilizes modified waste plastic particles, desulfurized fly ash and mineral powder to prepare 3D printed lightweight concrete, combining the resource utilization of waste plastics and industrial waste with 3D printing intelligent construction. On the one hand, it reduces the cost of 3D printed lightweight concrete, and on the other hand, it reuses waste, saves resources and protects the environment. (2) By subjecting the waste plastic particles to multiple chemical treatments, not only is the chemical state of the particle surface improved, and the particle surface changes from hydrophobic to hydrophilic, but the adhesion of the particle surface is also enhanced, and its interfacial bonding ability with concrete is improved, thereby improving the compressive strength of concrete.
[0074] (3) While applying waste plastic particles to 3D printed lightweight concrete, it can also ensure that the 3D printed lightweight concrete has good fluidity, extrudability, constructability and excellent compressive strength and elastic modulus.
[0075] In summary, this application utilizes waste foamed plastic particles for recycling, modifies them, and then incorporates them into 3D-printed lightweight concrete. Through the synergistic effect of the modified waste foamed plastic particles with other components, the concrete achieves the desired performance. This application combines the resource utilization of modified waste foamed plastic particles with 3D-printed intelligent construction, reducing the cost of 3D-printed lightweight concrete while reusing waste, saving resources, and protecting the environment. This application is conducive to promoting the development of 3D-printed lightweight concrete technology and has significant environmental and social benefits.
[0076] It should be noted that: In this article, “~” is used to represent the range of values, and the range of values represented by this expression includes two endpoint values.
[0077] The specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of this application, and are not intended to limit them; those skilled in the art can make adaptive adjustments within the concept and protection scope of this application.
[0078] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit it. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this application.
Claims
1. A 3D-printed lightweight concrete prepared from modified foamed plastic particles, characterized in that, It includes the following components: mineral powder, desulfurized fly ash, modified foamed plastic granules, fiber, alkali activator, defoamer, water-reducing agent, thickener, and water; The modified foamed plastic particles are obtained by treating mixture A with a surface modifier solution; wherein, mixture A is obtained by immersing the foamed plastic particles in an oxidant solution at a temperature of 60-80°C.
2. The 3D-printed lightweight concrete according to claim 1, characterized in that, The preparation process of the modified foamed plastic particles is as follows: The foamed plastic particles and the oxidant solution are mixed and stirred at 60℃~80℃ for 1~4h, and then dried to form the mixture A; a surface modifier solution is added to the mixture A, and after stirring for 2~6h, the solid and liquid are separated and the solid is dried to obtain the modified foamed plastic particles.
3. The 3D-printed lightweight concrete according to claim 1, characterized in that: The mass ratio of the foamed plastic particles to the oxidant solution is 1:(12-18). The mass ratio of the mixture A to the surface modifier solution is 1:(100-120).
4. The 3D-printed lightweight concrete according to claim 1, characterized in that: The oxidant is a mixture of potassium permanganate solution and sulfuric acid, wherein the weight ratio of potassium permanganate solution to sulfuric acid is 1:(0.5-1); the mass percentage concentration of potassium permanganate solute in the oxidant solution is 1.0%-4.0%. The surface modifier solution is an aqueous solution of isocyanate-based silane coupling agent.
5. The 3D-printed lightweight concrete according to claim 1, characterized in that: The foamed plastic particles are waste foamed plastic particles, which are obtained by recycling and grinding the plastic in waste foamed plastic products.
6. The 3D-printed lightweight concrete according to claim 1, characterized in that: The waste foam plastic products include waste foam shoe soles.
7. The 3D-printed lightweight concrete according to claim 1, characterized in that: By weight, its components include: 400-800 parts mineral powder, 100-400 parts desulfurized fly ash, 900-1500 parts modified foamed plastic granules, 5-11 parts fiber, 1-7 parts defoamer, 50-150 parts alkali activator, 3-11 parts water-reducing agent, 2-10 parts thickener, and 200-400 parts water.
8. The 3D-printed lightweight concrete according to claim 1, characterized in that: The mineral powder is S95 mineral powder, with a 28-day activity of 91-105% and a density of 2.93-2.99 g / cm³. 3 ; The desulfurized fly ash has a fineness of 8-9% and a density of 2.14-2.34 g / cm³. 3 The activity is 65-75%; The fiber includes one or more combinations of polypropylene fiber, basalt fiber, and plant fiber; The alkaline activator includes one or more combinations of sodium silicate, sodium hydroxide, and magnesium oxide. The defoamer includes one or more combinations of chloroethane, toluene, polysiloxane polyether, and polymeric propylene oxide.
9. The 3D-printed lightweight concrete according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate water-reducing agent with a water reduction rate of ≥30%; The thickener includes at least one of inorganic thickeners, lignocellulose thickeners, ether thickeners, and polyacrylate thickeners.
10. A method for preparing 3D-printed lightweight concrete using modified foamed plastic particles as described in any one of claims 1-9, characterized in that, The preparation steps include the following: Weigh out the desulfurized fly ash and alkali activator, and mix them evenly to form the first mixture; Mineral powder, modified foamed plastic particles and fibers are added to the first mixture, and the mineral powder, modified foamed plastic particles and fibers are mixed evenly to obtain the second mixture; Add water to the second mixture and mix well to obtain a third mixture; Add defoamer, water-reducing agent and thickener to the third mixture, stir evenly, and obtain the 3D printed lightweight concrete.