Concrete slurry for underwater 3D printing and construction method

Abstract

The application discloses a kind of concrete slurry of underwater 3D printing, belong to building material technical field, the slurry includes main material, auxiliary material and recycled material, by weight fraction, the main material is composed of 100-120 parts of cement, 15-30 parts of silica ash, 10-15 parts of coral sand, 8-12 parts of quartz sand, 35-40 parts of water;The auxiliary material is composed of water reducing agent 1-2.5 parts, anti-dispersion agent 1-1.5 parts, cellulose 0.5-1 part, plant glue 0.8-1.5 parts;The recycled material is marine recycled plastic body, including polyethylene terephthalate and / or polystyrene and / or polypropylene and / or polyethylene 20-35 parts.The underwater 3D printing concrete slurry of the application can meet the liquidity when printing, also has the requirement of meeting anti-dispersibility, and the marine garbage recycling material is combined with the substance applied, can consume such substances without affecting the practicability of the product of the application, help environmental protection.

Description

Technical Field

[0001] This invention belongs to the field of building materials technology, specifically relating to an underwater 3D printed concrete slurry and its construction method. Background Technology

[0002] Infrastructure construction in marine environments has developed rapidly in recent years, but challenges remain, including complex environments, significant risks, and difficulties in formwork erection during construction. 3D printing technology, with its advantages of mold-free construction, mechanized operation, and additive manufacturing, has become a leading smart construction technology. Therefore, 3D printed concrete technology shows significant application potential in the foundation construction and reinforcement of underwater structures.

[0003] With the rapid development of society today, the marine environment has also been affected by human activities, resulting in a large amount of marine debris. Marine debris mainly refers to persistent, man-made or processed solid waste in the marine and coastal environment. Marine debris affects the marine landscape, threatens navigational safety, and impacts the health of marine ecosystems, thereby negatively affecting the marine economy. Some of this marine debris remains on beaches, while some floats on the surface or sinks to the seabed.

[0004] Marine debris is categorized into floating debris, beach debris, and seabed debris. Monitoring results show that styrofoam accounts for the largest proportion of debris in all three categories, nearly half of all marine debris, severely impacting the marine environment. Dissolving or recycling this type of debris could greatly improve the marine environment and benefit it. Summary of the Invention

[0005] In view of this, the purpose of the present invention is to provide an underwater 3D printed concrete slurry and a construction method thereof.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A concrete slurry for underwater 3D printing, the slurry comprising main materials, auxiliary materials, and recycled materials, wherein, by weight, the main materials consist of 100-120 parts cement, 15-30 parts silica fume, 10-15 parts coral sand, 8-12 parts quartz sand, and 35-40 parts water; the auxiliary materials consist of 1-2.5 parts water-reducing agent, 1-1.5 parts anti-dispersing agent, 0.5-1 part cellulose, and 0.8-1.5 parts plant gum; the recycled materials are marine recycled plastics, comprising 20-35 parts polyethylene terephthalate and / or polystyrene and / or polypropylene and / or polyethylene.

[0008] Furthermore, the pH value of the water is less than 12.

[0009] Furthermore, the cement is silicate cement.

[0010] Furthermore, the silica fume has an average particle size of 0.16-0.20 μm, the quartz sand has a particle size of 0.215-0.463 μm, and the apparent density is 2.650 g / cm³. 3 Bulk density 1.538 g / cm³ 3 .

[0011] Furthermore, the water-reducing agent is a polycarboxylate high-performance water-reducing agent, and the cellulose is methylcellulose.

[0012] Furthermore, it includes a construction method for 3D-printed concrete slurry.

[0013] S1. After washing the recycled ocean plastic body, dry it to remove surface moisture, and then heat it at 250-300 degrees Celsius until it becomes viscous.

[0014] S2. Mix cement, silica fume, anti-dispersant agent, finely ground coral sand and quartz sand evenly, then add water, water-reducing agent, cellulose and plant gum and continue to mix evenly to obtain the mixture;

[0015] S3. Pour the viscous recycled plastic body into the mixture and mix well to obtain concrete paste;

[0016] S4. Import the drawn printing path file into the 3D printer's control software, pour the concrete slurry from step S3 into the 3D printer's mixing drum, and operate the printer control software to start printing.

[0017] S5. After underwater 3D printing, the material is cured in water until it is fully formed.

[0018] Furthermore, the printer has a nozzle travel speed of 10-50 mm / s, a rotation speed of 2-12 rad / s, and a printing height of 20-30 mm.

[0019] Further, in step S2, cement, silica fume, anti-dispersant agent, finely ground coral sand and quartz sand are mixed at low speed in a mixer for 3-5 minutes; after adding water, water-reducing agent, cellulose and plant gum, they are first mixed at low speed for 5-7 minutes, and then the heated recycled plastic body is added and the speed is increased and mixed for another 5-10 minutes.

[0020] Furthermore, the low-speed mixing rate of the cement, silica fume, anti-dispersant agent, coral sand and quartz sand is 30-70 rpm / min, the low-speed mixing rate after adding water, water-reducing agent, cellulose and plant gum is 30-70 rpm / min, and the high-speed mixing rate after speed-up is 200-300 rpm / min.

[0021] In this application, cement is used as the main raw material for concrete paste. The SiO2 content in the cement used in this application is kept within a suitable range, which can keep the stability and fluidity of the finished concrete paste relatively balanced. If the SiO2 content in the cement is too high, it will affect the hardening time and strength of the cement. If the SiO2 content in the cement is too low, it will affect the quality of the cement, resulting in insufficient strength and stability of the cement.

[0022] The silica fume in this application has a particle size of 0.16-0.20 μm. The smaller particle size of silica fume results in a larger specific surface area. When silica fume is added to concrete mortar, its larger surface area can adsorb more water molecules, thereby reducing the fluidity of the mortar. Moreover, silica fume particles have high activity. Adding silica fume can fill the voids between cement particles in the original concrete mortar and react chemically with free CaO, thereby significantly improving the workability of 3D printing mortar, increasing the early strength of 3D printed concrete specimens, and improving their various mechanical properties.

[0023] This application uses a water-reducing agent, which has excellent viscosity-reducing properties. The working principle is that the surface of the water-reducing agent carries a negative charge, and the cement particles are dispersed under the action of repulsion. The water trapped in the cement particles is released, thereby improving the fluidity of the concrete.

[0024] The anti-dispersing agent in this application is the most critical admixture for underwater anti-dispersing concrete. It can increase the viscosity of concrete, thereby enabling the freshly mixed concrete paste to achieve the effect of not dispersing or segregating underwater.

[0025] In this application, coral sand is used to replace natural river sand in the mix design of concrete, which can increase the compressive strength and splitting tensile strength of the finished concrete paste. The drying shrinkage performance, early crack resistance, chloride ion penetration resistance and carbonation resistance of coral sand concrete are better than those of river sand concrete. Moreover, due to its uneven and porous nature, the bonding force of the interface transition zone of coral sand is greater than that of river sand concrete, which greatly improves the structural performance of its interface.

[0026] The plant-based adhesive in this application has properties such as adhesion, gelation, and stability, which can increase the adhesion of underwater concrete slurry and reduce its likelihood of cracking.

[0027] The cellulose in this application is a nonionic cellulose ether, which is produced by introducing methyl groups into cellulose through etherification, and can be used as a mixture for cement, mortar, joint sealant, etc.

[0028] When the marine recycled plastic body in this application is heated to 263-300°C, it will gel, and become viscous, thus encapsulating the mixture of main and auxiliary materials and giving it a certain degree of firmness.

[0029] The beneficial effects of this invention are as follows:

[0030] 1. The underwater 3D printing concrete slurry of the present invention can meet the requirements of fluidity during printing and anti-dispersion. Moreover, by combining marine debris recycling materials with the substances applied for, such substances can be consumed without affecting the practicality of the product of the present invention, which is conducive to environmental protection.

[0031] 2. Through underwater 3D printed concrete experiments, this invention proposes a mix design concept for underwater 3D printed concrete and identifies the key influencing factors in the mix design of underwater 3D printed concrete.

[0032] 3. The raw materials for underwater 3D printing concrete of this invention are inexpensive and economical, making it suitable for industrial applications.

[0033] Other advantages, objectives, and features of the invention will be set forth in the following description and will be apparent to those skilled in the art in some respects, or may be learned by practice of the invention. The objectives and other advantages of the invention can be realized and obtained through the following description. Attached Figure Description

[0034] To make the purpose, technical solution, and beneficial effects of the invention clearer, the following figures are provided for illustration:

[0035] Figure 1 The image shows the finished product of underwater 3D printed concrete prepared according to Embodiment 1 of the invention. Detailed Implementation

[0036] A concrete slurry for underwater 3D printing and its construction method

[0037] Example 1

[0038] S1. Wash 30 portions of recycled ocean plastic, dry them to remove surface moisture, and then heat them at 260 degrees Celsius until they become viscous.

[0039] S2. Mix 100 parts cement, 15 parts silica fume, 1 part anti-dispersant agent, 15 parts finely ground coral sand and 8 parts quartz sand at 30 rpm / min for 4 minutes. Then add 37 parts water, 2 parts water-reducing agent, 0.5 parts cellulose and 1 part plant gum and mix at 45 rpm / min for 5 minutes to obtain the mixture.

[0040] S3. Pour the viscous recycled plastic body into the mixture and stir at 220 rpm / min for 8 minutes to obtain a concrete paste.

[0041] S4. Pour the concrete slurry from step S3 into the mixing drum of the 3D printer and print it at a nozzle travel speed of 20 mm / s, a rotation speed of 3 rad / s, and a printing height of 20 mm.

[0042] S5. After 3D printing underwater, the product is cured in water until it is fully formed.

[0043] Example 2

[0044] S1. Wash 20 portions of recycled ocean plastic, dry them to remove surface moisture, and then heat them at 260 degrees Celsius until they become viscous.

[0045] S2. Mix 120 parts cement, 25 parts silica fume, 1.5 parts anti-dispersant agent, 10 parts finely ground coral sand and 12 parts quartz sand at 70 rpm / min for 4 minutes. Then add 40 parts water, 1.5 parts water-reducing agent, 0.75 parts cellulose and 1.5 parts plant gum and mix at 60 rpm / min for 5 minutes to obtain the mixture.

[0046] S3. Pour the viscous recycled plastic body into the mixture and stir at 280 rpm / min for 8 minutes to obtain a concrete paste.

[0047] S4. Pour the concrete slurry from step S3 into the mixing drum of the 3D printer and print it at a nozzle travel speed of 30 mm / s, a rotation speed of 6 rad / s, and a printing height of 30 mm.

[0048] S5. After 3D printing underwater, the product is cured in water until it is fully formed.

[0049] Example 3

[0050] S1. Wash 35 portions of recycled marine plastic, dry them to remove surface moisture, and then heat them at 260 degrees Celsius until they become viscous.

[0051] S2. Mix 100 parts cement, 15 parts silica fume, 1 part anti-dispersant agent, 15 parts finely ground coral sand and 8 parts quartz sand at 30 rpm / min for 4 minutes. Then add 35 parts water, 2.5 parts water-reducing agent, 0.5 parts cellulose and 0.8 parts plant gum and mix at 50 rpm / min for 5 minutes to obtain the mixture.

[0052] S3. Pour the viscous recycled plastic body into the mixture and stir at 300 rpm / min for 10 minutes to obtain a concrete paste.

[0053] S4. Pour the concrete slurry from step S3 into the mixing drum of the 3D printer and print it at a nozzle travel speed of 50 mm / s, a rotation speed of 10 rad / s, and a printing height of 20 mm.

[0054] S5. After 3D printing underwater, the product is cured in water until it is fully formed.

[0055] To demonstrate the superiority of the present invention, comparative examples 1 and 2 are provided herein.

[0056] Comparative Example 1

[0057] S1. Mix 100 parts cement, 15 parts silica fume, 1 part anti-dispersant agent, 15 parts finely ground coral sand and 8 parts quartz sand at 30 rpm / min for 4 minutes. Then add 37 parts water, 2 parts water-reducing agent, 0.5 parts cellulose and 1 part plant gum and mix at 45 rpm / min for 5 minutes to obtain the mixture.

[0058] S2. Pour the viscous recycled plastic body into the mixture and stir at 220 rpm / min for 8 minutes to obtain a concrete paste.

[0059] S3. Pour the concrete slurry from step S2 into the mixing drum of the 3D printer and print it at a nozzle travel speed of 100 mm / s, a rotation speed of 10 rad / s, and a printing height of 40 mm.

[0060] S4. After 3D printing underwater, the product is cured in water until it is fully formed.

[0061] Comparative Example 2

[0062] S1. Wash 45 portions of recycled ocean plastic, dry them to remove surface moisture, and then heat them at 260 degrees Celsius until they become viscous.

[0063] S2. Mix 100 parts cement, 15 parts silica fume, 1 part anti-dispersant agent, 15 parts finely ground coral sand and 8 parts quartz sand at 30 rpm / min for 4 minutes. Then add 35 parts water, 2.5 parts water-reducing agent, 0.5 parts cellulose and 0.8 parts plant gum and mix at 50 rpm / min for 5 minutes to obtain the mixture.

[0064] S3. Pour the viscous recycled plastic body into the mixture and stir at 300 rpm / min for 10 minutes to obtain a concrete paste.

[0065] S4. Pour the concrete slurry from step S3 into the mixing drum of the 3D printer and print it at a nozzle travel speed of 5 mm / s, a rotation speed of 15 rad / s, and a printing height of 20 mm.

[0066] S5. After 3D printing underwater, the product is cured in water until it is fully formed.

[0067] The performance of the finished concrete from Examples 1-3 and Comparative Examples 1-2 of this invention was tested, and the test results are shown in the table below:

[0068]

[0069] As shown in the table above, the compressive strength, tensile strength, and shear strength of the underwater 3D printed concrete prepared by Examples 1-3 of this invention are all superior to those of the finished products prepared by Comparative Examples 1-2. Although the properties of the prepared concrete decreased slightly after 24 hours, the changes were not significant. Overall, the performance of the finished concrete prepared by this invention is still superior to that of the concrete prepared by the comparative examples.

[0070] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A concrete slurry for underwater 3D printing, characterized in that: The slurry comprises main materials, auxiliary materials, and recycled materials. By weight, the main materials consist of 100-120 parts cement, 15-30 parts silica fume, 10-15 parts coral sand, 8-12 parts quartz sand, and 35-40 parts water. The auxiliary materials consist of 1-2.5 parts water-reducing agent, 1-1.5 parts anti-dispersing agent, 0.5-1 part cellulose, and 0.8-1.5 parts plant gum. The recycled materials are marine recycled plastics, including 20-35 parts of polyethylene terephthalate and / or polystyrene and / or polypropylene and / or polyethylene. The cement is silicate cement; The silica fume has an average particle size of 0.16-0.20 μm, the quartz sand has a particle size of 0.215-0.463 μm, and the apparent density is 2.650 g / cm³. 3 Bulk density 1.538 g / cm³ 3 ; The heating temperature of the marine recycled plastic body is 250-300 degrees Celsius, and it becomes viscous after heating.

2. The underwater 3D printed concrete slurry according to claim 1, characterized in that: The pH value of the water is less than 12.

3. The underwater 3D printed concrete slurry according to claim 1, characterized in that: The water-reducing agent is a polycarboxylate high-performance water-reducing agent, and the cellulose is methylcellulose.

4. The construction method for underwater 3D printed concrete slurry as described in claim 1, characterized in that: S1. After washing the recycled ocean plastic body, dry it to remove surface moisture, and then heat it at 250-300 degrees Celsius until it becomes viscous. S2. Mix cement, silica fume, anti-dispersant agent, finely ground coral sand and quartz sand evenly, then add water, water-reducing agent, cellulose and plant gum and continue to mix evenly to obtain the mixture; S3. Pour the viscous recycled plastic body into the mixture and mix well to obtain concrete paste; S4. Import the drawn printing path file into the 3D printer's control software, pour the concrete slurry from step S3 into the 3D printer's mixing drum, and operate the printer control software to start printing. S5. After 3D printing underwater, the product is cured in water until it is fully formed.

5. The construction method for 3D-printed concrete slurry according to claim 4, characterized in that: The printer has a nozzle travel speed of 10-50 mm / s, a rotation speed of 2-12 rad / s, and a printing height of 20-30 mm.

6. The construction method for 3D-printed concrete slurry according to claim 5, characterized in that: In step S2, cement, silica fume, anti-dispersant agent, finely ground coral sand and quartz sand are mixed at low speed in a mixer for 3-5 minutes; after adding water, water-reducing agent, cellulose and plant gum, the mixture is first mixed at low speed for 5-7 minutes, and then the heated recycled plastic body is added and the speed is increased and the mixture is mixed for another 5-10 minutes.

7. The construction method for 3D-printed concrete slurry according to claim 6, characterized in that: The low-speed mixing rate of the cement, silica fume, anti-dispersant agent, coral sand and quartz sand is 30-70 rpm / min. After adding water, water-reducing agent, cellulose and plant gum, the low-speed mixing rate is 30-70 rpm / min. After speeding up, the high-speed mixing rate is 200-300 rpm / min.

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