Seawater and sea sand concrete material for on-demand condensation 3D printing and preparation method of seawater and sea sand concrete material

Abstract

The invention discloses a seawater sea sand concrete material for on-demand condensation 3D printing and a preparation method thereof. The material comprises a mortar component A and a neat paste component B, the mortar component A comprises the following components in parts by weight: 80-120 parts of a cementing material, 80-120 parts of sea sand, 20-40 parts of seawater, 0.1-0.14 part of a water reducing agent and 0.02-0.06 part of a retarder; the neat paste component B comprises the following components in parts by weight: 5-15 parts of seawater, 5-7 parts of a coagulating activator and 20-30 parts of quartz powder; the weight ratio of the component A to the component B is (5: 1)-(6: 1). The preparation method comprises the following steps: respectively mixing the components of the mortar A and the neat paste B, pumping into a mixing device of a 3D printer, stirring, and extruding from a printing head. According to the invention, accurate regulation and control of rheological properties and setting time of the seawater and sea sand cement-based material are realized through the high fluidity and delayed coagulation characteristics of the component A cement-based mortar and the rapid coagulation accelerating effect of the component B coagulation accelerating activator.

Description

Technical Field

[0001] The present invention relates to a concrete material for 3D printing and a preparation method thereof, and particularly to a seawater and sea sand concrete material for on-demand setting 3D printing and a preparation method thereof. Background Art

[0002] With the increasingly scarce resources of fresh water river sand, in coastal areas, it has become an inevitable trend to prepare concrete using seawater and sea sand. Facing the problems such as complex construction environment, diverse engineering structures, and limited transportation conditions in ocean engineering construction, concrete 3D printing technology has significant advantages in aspects such as formwork-free construction, high degree of automation, and saving manpower and time. Developing seawater and sea sand concrete suitable for 3D printing technology and its application technology has important practical significance.

[0003] Traditional 3D printing concrete generally uses fast-hardening materials, and the open time of such materials usually does not exceed 1 h. This time limit results in the pumping distance of 3D printing concrete usually not exceeding 10 m. At the same time, due to the slow evolution speed of the materials, the height of a single print often cannot exceed 1.5 m. When seawater and sea sand are used as 3D printing construction materials, the ionic components in seawater and sea sand will significantly accelerate the early hydration reaction of cement, resulting in an initial slump drop of about 15% - 20% and an initial setting time shortening of about 20% - 30%. This change makes the problems of too fast initial hardening speed of the materials, too short pumping distance, and limited construction height particularly prominent, significantly restricting the wide application of 3D printing technology in the coastal construction field.

[0004] Therefore, how to optimize the material design and control the printing time to ensure that it has a long pumping distance and can quickly harden after extrusion has become the key challenge to promote the application of 3D printing technology for seawater and sea sand concrete. Summary of the Invention

[0005] Object of the Invention: The object of the present invention is to provide a seawater and sea sand concrete material for on-demand setting 3D printing that has a long pumping distance and can quickly harden after extrusion;

[0006] The second object of the present invention is to provide a preparation method of the seawater and sea sand concrete material for on-demand setting 3D printing.

[0007] Technical Solution: The seawater and sea sand concrete material for on-demand setting 3D printing described in the present invention includes mortar component A and neat cement component B:

[0008] The mortar component A includes, by weight: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.1 - 0.14 parts of water reducing agent, and 0.02 - 0.06 parts of retarder;

[0009] The B component of the neat paste includes, by weight parts: 5 - 15 parts of seawater, 5 - 7 parts of coagulation accelerator, and 20 - 30 parts of quartz powder;

[0010] The weight ratio of the A component to the B component is 5:1 - 6:1.

[0011] Among them, the seawater is one of the seawaters in the Bohai Sea, the Yellow Sea, the East China Sea, or the South China Sea.

[0012] Among them, the sea sand is one of the submarine sands in the Bohai Sea, the Yellow Sea, the East China Sea, or the South China Sea, and the particle size range is 0.075 - 4.75 mm.

[0013] Among them, when the seawater and sea sand are the seawater and sea sand in the Bohai Sea area, the A component of the mortar includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.1 - 0.12 parts of water - reducing agent, and 0.02 - 0.04 parts of setting - retarder; the B component of the neat paste includes, by weight parts: 5 - 15 parts of seawater, 6 - 7 parts of coagulation accelerator, and 20 - 30 parts of quartz powder.

[0014] When the seawater and sea sand are the seawater and sea sand in the Yellow Sea area, the A component of the mortar includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.11 - 0.13 parts of water - reducing agent, and 0.03 - 0.05 parts of setting - retarder; the B component of the neat paste includes, by weight parts: 5 - 15 parts of seawater, 5 - 6 parts of coagulation accelerator, and 20 - 30 parts of quartz powder.

[0015] When the seawater and sea sand are the seawater and sea sand in the East China Sea area, the A component of the mortar includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.1 - 0.11 parts of water - reducing agent, and 0.02 - 0.03 parts of setting - retarder; the B component of the neat paste includes, by weight parts: 5 - 15 parts of seawater, 6 - 7 parts of coagulation accelerator, and 20 - 30 parts of quartz powder.

[0016] When the seawater and sea sand are the seawater and sea sand in the South China Sea area, the A component of the mortar includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.13 - 0.14 parts of water - reducing agent, and 0.04 - 0.06 parts of setting - retarder; the B component of the neat paste includes, by weight parts: 5 - 15 parts of seawater, 5 - 6 parts of coagulation accelerator, and 20 - 30 parts of quartz powder.

[0017] Among them, the setting - retarder is sucrose.

[0018] Among them, the water - reducing agent is a dry - powder polycarboxylate water - reducing agent.

[0019] Among them, the coagulation accelerator is a sulfoaluminate accelerator, and its main components are aluminum sulfate and sodium aluminate, and the mass ratio of aluminum sulfate to sodium aluminate is 4:1.

[0020] Among them, the particle size of the quartz powder is 20-45μm.

[0021] The preparation method of the above seawater and sea sand concrete material for on-demand coagulation 3D printing includes the following steps:

[0022] (1) Mix and stir the cementitious material, water reducer, retarder and sea sand, add seawater, and obtain the mortar A component after stirring.

[0023] (2) Mix seawater, coagulation accelerator and quartz powder to obtain the neat cement B component.

[0024] (3) Pump the mortar A component and the neat cement B component into the mixing device of the 3D printer respectively. After mixing and stirring, extrude from the print head to obtain the seawater and sea sand concrete material.

[0025] Among them, in step (1), the stirring speed is 20-30r / min, and the stirring time is 1-3min; after adding seawater, the stirring speed is 20-30r / min, and the stirring time is 2-4min.

[0026] Among them, in step (2), the stirring speed is 20-30r / min, and the stirring time is 2-4min.

[0027] Among them, in step (3), the stirring speed when the mortar A component and the neat cement B component are mixed is 0-250r / min, and the mixing time is 5-30s.

[0028] The initial fluidity of the mortar A component material obtained by the present invention is not less than 300mm, and the initial setting time is greater than 3h. The initial setting time of the obtained seawater and sea sand concrete material is less than 30min.

[0029] Principle of the invention: The use of seawater may cause the PCEs to fail. Calcium and sulfate ions in seawater will adsorb on the surface of cement particles and compete with PCEs for adsorption, reducing the coverage of PCEs on the surface of cement particles. A certain amount of inorganic salts (mainly chloride salts) often adhere to the surface of sea sand. This part of the salts will slowly dissolve in the mixing water or pore solution, releasing ions such as chlorine, calcium, sodium and potassium, which will also promote the setting and hydration of cement. In response to the dual challenges of material failure and coagulation out-of-control caused by the seawater and sea sand system, the present invention constructs a "pumping stabilization - extrusion excitation type" two-stage regulation system, and its mechanism of action is as follows:

[0030] During the pumping stage, to address the problem of competitive adsorption between seawater calcium and sulfate ions and PCEs, the present invention introduces sucrose as a retarding regulator. By precisely controlling the ratio of the dosage of dry powder PCEs to the sucrose retarder, a dynamic adsorption equilibrium is constructed, effectively maintaining the steric hindrance effect of PCEs, keeping the fluidity of mortar component A above 300 mm, overcoming the problem of dispersion failure caused by ionic competitive adsorption when using PCEs alone, and ensuring pumping stability.

[0031] During the extrusion construction stage, through the separate transportation of component A and component B, component B introduces a sulfoaluminate accelerator, and the released Al3+ reacts with SO4 in seawater 2- to generate ettringite (AFt) crystal nuclei, accelerating the dissolution-precipitation process of the C3S phase, controlling the initial setting time within a window period of less than 30 min, achieving setting regulation, solving the technical bottleneck of uncontrolled setting in traditional seawater systems, and realizing on-demand setting regulation for 3D printing of seawater and sea sand concrete materials.

[0032] Target parameter setting: Set the initial fluidity of mortar component A materials to be at least greater than or equal to 300 mm, and the initial setting time to exceed 3 h. A fluidity greater than or equal to 300 mm is used to achieve high fluidity, facilitating subsequent transportation and pumping during printing. The initial setting time exceeding 3 h is set considering factors such as equipment performance, material supply, and consumption speed, and it also better matches the material transportation of commercial concrete mixing stations. The initial setting time of the material after mixing components A and B is within 30 min to ensure rapid structure construction and high height accumulation, preventing collapse and deformation due to insufficient early strength of the material.

[0033] Beneficial effects: Compared with the prior art, the present invention has achieved the following remarkable effects:

[0034] (1) The present invention constructs a dynamic equilibrium in the seawater ionic competitive adsorption environment by precisely regulating the ratio of dry powder polycarboxylate superplasticizer (0.10 - 0.14 parts) to sucrose retarder (0.02 - 0.06 parts) in mortar component A. At the same time, 5 - 7 parts of sulfoaluminate accelerator are introduced through component B, and the released Al 3+ reacts with seawater SO4 2- to in-situ generate ettringite crystal nuclei, enabling it to have a long pumping distance and rapidly harden after extrusion, ensuring the smooth progress of the printing process, effectively solving the key technical bottlenecks such as short printing and pumping distances and insufficient construction height caused by uncontrolled setting in traditional seawater systems, and significantly improving the structural forming accuracy and construction efficiency of 3D printing in ocean engineering;

[0035] (2) The present invention constructs a material system adaptable to the sea area. For seawater ionic concentrations in different sea areas, such as Cl -Content: South China Sea 33319 mg / L > Yellow Sea 19360 mg / L > Bohai Sea 17359 mg / L > East China Sea 14823 mg / L, and the characteristics of sea sand, that is, the chloride ion content is 0.035 - 0.058%. By dynamically adjusting the ratio of component A / B, that is, 5:1 to 6:1, and the dosage of admixtures, such as increasing the water reducing agent to 0.14 parts for the South China Sea area to cope with high salinity, the cross-sea universality of material properties is achieved, ensuring the efficient utilization of marine resources and engineering reliability;

[0036] (3) The present invention realizes a new low-carbon utilization mode of marine resources, replacing traditional mixing fresh water with 100% seawater, achieving zero consumption of fresh water, comprehensively replacing river sand with sea sand, and combining 3D printing without formwork construction technology, significantly reducing the material transportation energy consumption and carbon emissions of marine engineering construction. While ensuring the structural performance, this mode has significant ecological and economic benefits. Detailed implementation mode

[0037] The present invention will be further described in detail below.

[0038] Example 1

[0039] A seawater and sea sand concrete material for on-demand setting 3D printing, comprising mortar component A and neat cement component B;

[0040] The mortar component A material includes 100 parts of ordinary Portland cement with a strength grade of 42.5, 100 parts of sea sand from the Yellow Sea area, 30 parts of Yellow Sea seawater, 0.12 parts of dry powder polycarboxylate water reducing agent, and 0.04 parts of sucrose; the neat cement component B includes: 10 parts of Yellow Sea seawater, 5 parts of sulfoaluminate quick-setting agent, and 25 parts of quartz powder. Among them, the main components of the sulfoaluminate quick-setting agent are aluminum sulfate and sodium aluminate, and the mass ratio of aluminum sulfate to sodium aluminate is 4:1; the main particle size of the quartz powder is 20 - 45 μm.

[0041] The preparation method of the above-mentioned concrete material for on-demand setting 3D printing includes the following steps:

[0042] S1. Mix 100 parts of ordinary Portland cement with a strength grade of 42.5, 0.12 parts of dry powder polycarboxylate water reducing agent, 0.04 parts of sucrose, and 100 parts of sea sand from the Yellow Sea area in a mixer at a stirring speed of 20 - 30 r / min for a stirring time of 1 - 3 min, then add 30 parts of Yellow Sea seawater and mix evenly again at a stirring speed of 20 - 30 r / min for a stirring time of 2 - 4 min to obtain mortar component A;

[0043] S2. Mix 10 parts of Yellow Sea seawater, 5 parts of sulfoaluminate quick-setting agent, and 25 parts of quartz powder at a stirring speed of 20 - 30 r / min for a stirring time of 2 - 4 min to obtain neat cement component B;

[0044] S3. Pump the mortar A component and the neat cement B component from two pipelines. The weight ratio of the A component to the B component is 5.75:1. The two components are transported to the mixing and conveying bin of the 3D printer through a rotary feeder, mixed and stirred in the bin, and then extruded through a screw extrusion print head to obtain a concrete material based on the on-demand setting 3D printing process. The specimens are immersed in the Yellow Sea seawater for curing, and the curing environment temperature is controlled at 20 °C and the relative humidity is 65%.

[0045] Example 2

[0046] A seawater and sea sand concrete material for on-demand setting 3D printing, comprising a mortar A component and a neat cement B component;

[0047] The mortar A component material includes 100 parts of ordinary Portland cement of strength grade 42.5, 100 parts of sea sand from the East China Sea, 30 parts of East China Sea seawater, 0.1 part of dry powder polycarboxylate water reducer, and 0.03 part of sucrose; the neat cement B component includes: 15 parts of East China Sea seawater, 6 parts of sulfoaluminate quick-setting agent, and 25 parts of quartz powder.

[0048] The method for preparing the concrete material for the on-demand setting 3D printing process in this Example 2 is as follows:

[0049] S1. Mix 100 parts of ordinary Portland cement of strength grade 42.5, 0.1 part of dry powder polycarboxylate water reducer, 0.03 part of sucrose, and 100 parts of sea sand from the East China Sea in a mixer at a stirring speed of 20 - 30 r / min for a stirring time of 1 - 3 min, then add 30 parts of East China Sea seawater and mix evenly again at a stirring speed of 20 - 30 r / min for a stirring time of 2 - 4 min to obtain the mortar A component;

[0050] S2. Mix 15 parts of East China Sea seawater, 6 parts of sulfoaluminate quick-setting agent, and 25 parts of quartz powder at a stirring speed of 20 - 30 r / min for a stirring time of 2 - 4 min to obtain the neat cement B component;

[0051] S3. Pump the mortar A component and the neat cement B component from two pipelines. The weight ratio of the A component to the B component is 5:1; the two components are transported to the mixing and conveying bin of the 3D printer through a rotary feeder, mixed and stirred in the bin, and then extruded through a screw extrusion print head to obtain a concrete material specimen for on-demand setting 3D printing. The specimens are immersed in the East China Sea seawater for curing, and the curing environment temperature is controlled at 20 °C and the relative humidity is 65%.

[0052] Example 3

[0053] A seawater and sea sand concrete material for on-demand setting 3D printing, comprising a mortar A component and a neat cement B component;

[0054] The mortar A component materials include 100 parts of ordinary Portland cement with a strength grade of 42.5, 100 parts of sea sand from the Bohai Sea area, 30 parts of Bohai Sea water, 0.11 part of dry powder polycarboxylate water reducer, and 0.03 part of sucrose; the neat paste B component includes: 12 parts of Bohai Sea water, 6 parts of sulfoaluminate accelerator, and 25 parts of quartz powder.

[0055] The method for preparing the concrete material for the 3D printing process with on-demand setting in this Example 3 is as follows:

[0056] S1. Mix 100 parts of ordinary Portland cement with a strength grade of 42.5, 0.11 part of dry powder polycarboxylate water reducer, 0.03 part of sucrose, and 100 parts of sea sand from the Bohai Sea area in a mixer at a stirring speed of 20 - 30 r / min for 1 - 3 min, then add 30 parts of Bohai Sea water and mix evenly again at a stirring speed of 20 - 30 r / min for 2 - 4 min to obtain the mortar A component.

[0057] S2. Mix 12 parts of Bohai Sea water, 6 parts of sulfoaluminate accelerator, and 25 parts of quartz powder at a stirring speed of 20 - 30 r / min for 2 - 4 min to obtain the neat paste B component.

[0058] S3. Pump the mortar A component and the neat paste B component from two pipes, and the weight ratio of the A component to the B component is 5.35:1; the two components are transported to the mixing and conveying bin of the 3D printer through a rotary feeder, mixed and stirred in the bin, and then extruded through a screw extrusion print head to obtain the concrete material based on the 3D printing process with on-demand setting. The specimen is immersed in the Bohai Sea water for curing, and the curing environment temperature is controlled at 20 °C and the relative humidity is 65%.

[0059] Example 4

[0060] A seawater and sea sand concrete material for 3D printing with on-demand setting includes a mortar A component and a neat paste B component;

[0061] The mortar A component materials include 100 parts of ordinary Portland cement with a strength grade of 42.5, 100 parts of sea sand from the South China Sea area, 30 parts of South China Sea water, 0.14 part of dry powder polycarboxylate water reducer, and 0.05 part of sucrose; the neat paste B component includes: 10 parts of South China Sea water, 5 parts of sulfoaluminate accelerator, and 25 parts of quartz powder.

[0062] The method for preparing the concrete material for the 3D printing process with on-demand setting in this Example 4 is as follows:

[0063] S1. Mix 100 parts of ordinary Portland cement with a strength grade of 42.5, 0.14 part of dry powder polycarboxylate superplasticizer, 0.05 part of sucrose, and 100 parts of sea sand from the South China Sea in a blender at a stirring speed of 20 - 30 r / min for 1 - 3 min. Then add 30 parts of South China Sea seawater and mix evenly again at a stirring speed of 20 - 30 r / min for 2 - 4 min to obtain the mortar A component;

[0064] S2. Mix 10 parts of South China Sea seawater, 5 parts of sulfoaluminate quick-setting agent, and 25 parts of quartz powder at a stirring speed of 20 - 30 r / min for 2 - 4 min to obtain the neat cement B component;

[0065] S3. Pump the mortar A component and the neat cement B component materials through two pipelines, and the weight ratio of the A component to the B component is 6:1. The two components are transported to the mixing and conveying bin of the 3D printer through a rotary feeder, mixed and stirred in the bin, and then extruded through a screw extrusion printing head to obtain the concrete material based on the on-demand setting 3D printing process. The specimens are immersed in the South China Sea seawater for curing, and the curing environment temperature is controlled at 20 °C and the relative humidity is 65%.

[0066] Comparative Example 1

[0067] Based on Example 1, the difference from Example 1 is that in the mortar A component, there are 0.08 part of dry powder polycarboxylate superplasticizer and 0.02 part of sucrose.

[0068] Comparative Example 2

[0069] Based on Example 1, the difference from Example 1 is that in the mortar A component, the sea sand is replaced by river sand and the seawater is replaced by deionized water; in the neat cement B component, the seawater is replaced by deionized water.

[0070] Comparative Example 3

[0071] Based on Example 1, the difference from Example 1 is that in the mortar A component, the sucrose is replaced by sodium gluconate.

[0072] Comparative Example 4

[0073] Based on Example 1, the difference from Example 1 is that in the neat cement B component, the sulfoaluminate quick-setting agent is replaced by hydroxypropyl methylcellulose with a viscosity of 200,000.

[0074] Test the fluidity of the 3D printing specimens for the mortar A components prepared in the above examples and comparative examples according to the "Test Method for Fluidity of Cement Mortar" (GB / T 2419 - 2005); test the initial setting time according to the "Determination Method for Setting Time of Cement Mortar" (GB / T 1346 - 2011).

[0075] The initial setting time of the on-demand coagulation 3D printing concrete prepared in the above examples and comparative examples was tested according to the "Testing Method for Setting Time of Cement Mortar" (GB / T 1346-2011); the 3-day compressive strength test was carried out according to the "Testing Method for Strength of Cement Mortar" (GB / T 17671-2021).

[0076] The above test results are shown in Table 1.

[0077] Table 1 Material Performance Test Table

[0078]

[0079] Compared with Example 1, in Comparative Example 1, the water reducing agent decreased from 0.12 parts to 0.08 parts, and sucrose decreased from 0.04 parts to 0.02 parts. The mortar fluidity decreased from 322 mm to 165 mm, significantly lower than the 300 mm pumping threshold, resulting in deteriorated pumping performance.

[0080] Compared with Example 1, in Comparative Example 2, sea sand was replaced with river sand and seawater was replaced with deionized water. The mortar fluidity slightly increased to 354 mm, but the initial setting time was extended to 292 min, and the 3-day strength of the printed specimen decreased to 22 MPa. This indicates that Cl - and SO4 2- plasma can accelerate the hydration reaction of cement minerals (such as C3A, C3S), shorten the induction period, show a coagulation promoting effect, and improve the early strength of the component.

[0081] Compared with Example 1, in Comparative Example 3, sucrose in Component A of the mortar was replaced with sodium gluconate. The fluidity was slightly lower than that of Example 1, and the initial setting time was shortened. Although sodium gluconate has a retarding property, premature coagulation caused fluidity loss, indicating that sucrose has better retarding adaptability in the seawater and sea sand system.

[0082] Compared with Example 1, in Comparative Example 4, the sulfoaluminate quick setting agent was replaced with hydroxypropyl methyl cellulose. The initial setting time of the printed specimen increased sharply to 168 min, far exceeding the construction window time, and the 3-day strength dropped sharply to 17.2 MPa, confirming that the sulfoaluminate quick setting agent has a better effect as a coagulation promoting activator.

[0083] Four groups of examples adopt sea area adaptability formulations for the Yellow Sea / East China Sea / Bohai Sea / South China Sea. By optimizing the ratio of water reducing agent - sucrose in Component A, i.e., 0.10 - 0.14 parts of water reducing agent + 0.03 - 0.05 parts of sucrose, and the dosage of the accelerating agent in Component B is 5 - 6 parts, their fluidity is all ≥300mm, meeting the rheological property requirements for long-distance pumping; the initial setting time of the printed specimens is controlled within the range of 19 - 27min, realizing the controllable time-varying property during the layer-by-layer stacking process; the 3d compressive strength is stable at 23.5 - 24.5MPa, an increase of 6.8 - 11.4% compared with the fresh water river sand reference group, verifying the microstructure strengthening effect of chloride ions in seawater and sea sand on the hydration products of binder. The differences in the properties of raw materials in different sea areas are compensated by micro-adjusting the proportion. For example, the water reducing agent in the South China Sea example is increased to 0.14 parts to cope with the high salinity, proving that the formulation system has the ability to expand regional adaptability. It provides a reliable technical path for the local utilization of marine resources and large-span 3D printing construction.

[0084] The seawater used in the present invention is the seawater in the Bohai Sea, Yellow Sea, East China Sea and South China Sea. The main ionic components of the seawater in the coastal sea areas are shown in Table 2.

[0085] Table 2 Main ionic components of seawater (mg / L)

[0086] sea area <![CDATA[Cl - > <![CDATA[Sodium + > <![CDATA[SO4 2- > <![CDATA[Mg 2+ > <![CDATA[Ca 2+ > <![CDATA[K + > East China Sea 14823 11741 2469 1123 327 315 Bohai Sea 17359 18520 2379 1170 372 329 Yellow Sea 19360 21560 2702 1297 408 388 South China Sea 33319 43235 3831 1029 543 409

[0087] The sea sand used is the sea sand in the Bohai Sea, Yellow Sea, East China Sea and South China Sea. The sea sand needs to meet the requirements for the composition of sea sand in the Technical Specification for Application of Sea Sand Concrete (JGJ206 - 2010). The relevant properties of the sea sand in the sea areas are shown in Table 3.

[0088] Table 3 Sea sand property table

[0089]

[0090] Generally speaking, the materials of the present invention include Component A of mortar and Component B of neat cement with specific compositions, successfully overcoming the deficiencies of traditional 3D printing seawater and sea sand concrete materials in terms of fluidity, setting time and strength, and having better adaptability and regulation ability. The present invention not only improves the application performance of 3D printing seawater and sea sand concrete, but also promotes its large-scale application in the fields such as marine engineering, providing new technical support for the sustainable development of marine engineering. Therefore, the 3D printing seawater and sea sand concrete materials and their preparation methods of the present invention have broad application prospects.

Claims

1. A seawater and sea sand concrete material for on-demand coagulation 3D printing, characterized in that It includes mortar component A and neat paste component B: The mortar component A includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.1 - 0.14 parts of water reducing agent, 0.02 - 0.06 parts of setting retarder; The neat paste component B includes, by weight parts: 5 - 15 parts of seawater, 5 - 7 parts of setting accelerating activator, 20 - 30 parts of quartz powder; The weight ratio of component A to component B is 5:1 - 6:

1.

2. The seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, wherein The seawater is one of the seawaters in the Bohai Sea, the Yellow Sea, the East China Sea or the South China Sea.

3. The seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, wherein The sea sand is one of the submarine sands in the Bohai Sea, the Yellow Sea, the East China Sea or the South China Sea, and the particle size range is 0.075 - 4.75mm.

4. The seawater-sea sand concrete material for on-demand condensation 3D printing according to claim 1, wherein When the seawater and sea sand are the seawater and sea sand in the Bohai Sea area, the mortar component A includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.1 - 0.12 parts of water reducing agent, 0.02 - 0.04 parts of setting retarder; the neat paste component B includes, by weight parts: 5 - 15 parts of seawater, 6 - 7 parts of setting accelerating activator, 20 - 30 parts of quartz powder.

5. The seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, characterized in that, When the seawater and sea sand are the seawater and sea sand in the Yellow Sea area, the mortar component A includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.11 - 0.13 parts of water reducing agent, 0.03 - 0.05 parts of setting retarder; the neat paste component B includes, by weight parts: 5 - 15 parts of seawater, 5 - 6 parts of setting accelerating activator, 20 - 30 parts of quartz powder.

6. The seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, characterized in that, When the seawater and sea sand are the seawater and sea sand in the East China Sea area, the mortar component A includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.1 - 0.11 parts of water reducing agent, 0.02 - 0.03 parts of setting retarder; the neat paste component B includes, by weight parts: 5 - 15 parts of seawater, 6 - 7 parts of setting accelerating activator, 20 - 30 parts of quartz powder.

7. The seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, wherein When the seawater and sea sand are the seawater and sea sand in the South China Sea area, the mortar component A includes, by weight parts: 80 - 120 parts of cementitious material, 80 - 120 parts of sea sand, 20 - 40 parts of seawater, 0.13 - 0.14 parts of water reducing agent, 0.04 - 0.06 parts of setting retarder; the neat paste component B includes, by weight parts: 5 - 15 parts of seawater, 5 - 6 parts of setting accelerating activator, 20 - 30 parts of quartz powder.

8. The seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, wherein The setting retarder is sucrose, the water reducing agent is dry powder polycarboxylate water reducing agent, and the setting accelerating activator is sulphoaluminate rapid setting agent.

9. A preparation method of the seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 1, characterized in that It includes the following steps: (1) Mix and stir the cementitious material, water reducing agent, setting retarder and sea sand, add seawater, and obtain mortar component A after stirring; (2) Mix seawater, setting accelerating activator and quartz powder to obtain neat paste component B; (3) Pump mortar component A and neat paste component B into the mixing device of the 3D printer respectively, after mixing and stirring, extrude from the printing head to obtain seawater sea sand concrete material.

10. The preparation method of the seawater and sea sand concrete material for on-demand condensation 3D printing according to claim 9, characterized in that, In step (1), the stirring speed is 20 - 30 r / min and the stirring time is 1 - 3 min; after adding seawater, the stirring speed is 20 - 30 r / min and the stirring time is 2 - 4 min; in step (2), the stirring speed is 20 - 30 r / min and the stirring time is 2 - 4 min.

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