Concrete 3D printing method, concrete 3D printing product and application

Abstract

The invention relates to a concrete 3D printing method, a concrete 3D printing product and application. The method comprises the following steps that concrete layers are printed layer by layer; a polymer emulsion layer is arranged between every two adjacent concrete layers, and a concrete 3D printing blank is obtained; the polymer emulsion layer comprises a response material of which the particle size is less than 10 microns; and the concrete 3D printing blank is placed in an external energy field, and the response material acts in the external energy field. The technical problem to be solved by the invention is how to provide the concrete 3D printing method, so that the interlayer binding force and the reinforcing steel bar-concrete matrix binding force of a concrete 3D printing product printed by using the method are improved, and meanwhile, the constructability and the appearance form of 3D printing concrete are not influenced, so that the concrete 3D printing method is more suitable for application.

Description

Technical Field

[0001] The present invention belongs to the technical field of concrete 3D printing, and in particular relates to a concrete 3D printing method and concrete 3D printed products and applications. Background Art

[0002] 3D printing is a process of printing materials layer by layer, stacking the layers, and finally forming a three-dimensional printed product. In recent years, extruded 3D printed concrete has been successfully applied to civil engineering, receiving widespread attention and great development potential. However, there are also many problems in the application of 3D printed concrete, including weak bonding between concrete layers and between steel bars and concrete matrix, which is manifested as low tensile strength and poor integrity of 3D printed concrete products. This is one of the most prominent problems in the application of 3D printed concrete, which seriously restricts the promotion and application of 3D printed concrete.

[0003] In the prior art, in order to improve the interfacial bonding strength of 3D printed concrete, some studies have reported that the above-mentioned problems are solved by methods of planting steel bars and applying interface agents. However, both the methods of planting steel bars and applying interface agents have defects. Specifically, the process of planting steel bars is relatively complicated during the application process, and the strength of the steel bar-matrix interface is low, and the risk of debarring is high. Existing interface agents, such as polyacrylic acid emulsions, can improve the interfacial bonding strength of 3D printed concrete to a certain extent, but the degree of improvement in the tensile strength of 3D printed concrete products is very limited, which is far from meeting the actual application requirements. Therefore, it is urgent to develop a method that can better improve the interfacial bonding strength of 3D printed concrete and better maintain the constructibility and appearance of 3D printed concrete, so as to facilitate the promotion and application of 3D printed concrete. Summary of the invention

[0004] The main purpose of the present invention is to provide a concrete 3D printing method and concrete 3D printed products and applications. The technical problem to be solved is how to provide a concrete 3D printing method so that the bonding strength between the layers and the steel bar-concrete matrix of the concrete 3D printed products printed by the method is improved, while not affecting the constructability and appearance of the 3D printed concrete, so that it is more suitable for application.

[0005] The purpose of the present invention and the technical problem to be solved are achieved by adopting the following technical solutions. According to a concrete 3D printing method proposed in the present invention, it comprises the following steps:

[0006] 1) Printing concrete layers layer by layer; a polymer emulsion layer is provided between two adjacent concrete layers to obtain a concrete 3D printed blank; the polymer emulsion layer includes a response material with a particle size of less than 10 μm;

[0007] 2) placing the concrete 3D printed blank in an external energy field, so that the responsive material acts in the external energy field.

[0008] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0009] Preferably, the aforementioned concrete 3D printing method further includes a step of planting reinforcement between step 1) and step 2), specifically including:

[0010] Setting a polymer emulsion layer on the steel bar surface and drying it;

[0011] The steel bar is inserted into the concrete 3D printed blank in a direction perpendicular to the concrete layer.

[0012] Preferably, in the aforementioned concrete 3D printing method, the polymer emulsion layer disposed between two adjacent concrete layers is formed by spraying polymer emulsion slurry; and the polymer emulsion layer disposed on the surface of the steel bar is formed by dipping or coating the polymer emulsion slurry.

[0013] Preferably, in the aforementioned concrete 3D printing method, the response material is selected from at least one of iron powder, aluminum powder and tin powder; the iron powder is selected from at least one of hydroxyl iron powder, carbon-based iron powder, carbonyl iron powder, nano iron powder and nano Fe3O4.

[0014] Preferably, in the aforementioned concrete 3D printing method, the response material includes a first response material and a second response material; the first response material can vibrate under the action of a high-frequency magnetic field; the second response material can absorb energy under microwave excitation; the first response material is selected from at least one of hydroxyl iron powder, carbon-based iron powder, carbonyl iron powder, nano iron powder and nano Fe3O4; the second response material is selected from aluminum powder and / or tin powder; the mass ratio of the first response material to the second response material is 1:0.5~10.

[0015] Preferably, in the aforementioned concrete 3D printing method, the mass of the single polymer emulsion layer disposed between two adjacent concrete layers is 0.5 to 1.5% of the mass of the cementitious material in the single concrete layer; and the coverage rate of the polymer emulsion layer disposed on the surface of the steel bar on the surface of the steel bar is ≥10%.

[0016] Preferably, in the aforementioned concrete 3D printing method, the external energy field is a magnetic field and / or an electromagnetic wave; the intensity of the magnetic field is 1 to 1000KA / m, the frequency is 50 to 200Hz, and the magnetization time is 5 to 20min; the frequency of the electromagnetic wave is 300MHz to 10GHz, and the radiation time is 5 to 20min; the direction in which the magnetic field and / or electromagnetic wave is applied is perpendicular to the surface of the concrete layer.

[0017] The purpose of the present invention and the solution to the technical problem are also achieved by adopting the following technical solutions. A concrete 3D printed product proposed in the present invention comprises:

[0018] N concrete layers, N is a natural number ≥ 2;

[0019] N-1 polymer emulsion layer is arranged between two adjacent concrete layers; the polymer emulsion layer includes a response material with a particle size of less than 10 μm.

[0020] The purpose of the present invention and the solution to its technical problems can be further achieved by adopting the following technical measures.

[0021] Preferably, the aforementioned concrete 3D printed product further comprises M implanted steel bars, where M is a natural number ≥ 2; and the surface of the implanted steel bars is also provided with the polymer emulsion layer.

[0022] The purpose of the present invention and the technical problem solved are also achieved by adopting the following technical solutions: An application of the aforementioned concrete 3D printed product is proposed in the present invention.

[0023] By means of the above technical solution, a concrete 3D printing method, a concrete 3D printed product and an application proposed by the present invention have at least the following advantages:

[0024] The concrete 3D printing method and concrete 3D printed products and applications proposed in the present invention introduce a responsive material into a polymer emulsion slurry, wherein the responsive material can absorb energy under an external energy field to exert its function; a large number of studies have shown that due to the construction process of extruded 3D printed concrete, the porosity between the interfaces of concrete layers and between the steel bars and the concrete matrix is ​​significantly higher than that of the matrix during the printing process, which reduces the cohesion between the concrete layers and between the steel bars and the matrix, thereby resulting in weak interface bonding force of 3D printed concrete and decreased overall performance; the technical solution of the present invention provides a concrete The 3D printing method, in addition to the conventional concrete 3D printing method, further provides a polymer emulsion layer between two adjacent concrete layers, and by providing the polymer emulsion layer between each printing layer of the 3D printed concrete, the responsive material with a particle size of less than 10 μm contained in the polymer emulsion can play a role in the external energy field; optionally, when reinforcing bars are implanted in the 3D printed concrete product, a polymer emulsion layer can also be provided on the surface of the implanted steel bars, so that the responsive material with a particle size of less than 10 μm contained in the polymer emulsion can play a role in the external energy field; specifically, the responsive material The external energy field plays the following roles: on the one hand, by strictly controlling the particle size of the response material to less than 10μm, making it small enough to control its movement through the high-frequency magnetic field; then, under the action of the high-frequency magnetic field, the response material vibrates at high frequency between the printed layers of concrete and at the interface between the steel bar and the concrete matrix, thereby vibrating and compacting the concrete between the layers and at the interface between the steel bar and the concrete matrix, and improving the bonding strength between the printed layers and between the steel bar and the matrix; on the other hand, under the synergistic effect of vibration, the polymer emulsion layer can make the water-based emulsion in it more conducive to penetrating into the upper and lower layers of the concrete, thereby forming The polymer network that runs through the concrete layer enhances the bonding between the concrete layers and improves the bonding strength of the 3D printed concrete products; at the same time, by strictly controlling the particle size of the response material to less than 10 μm, the force of the response material during high-frequency vibration is not too large, that is, the vibration area of ​​the response material is controlled in a very small micro-region where the interface between the concrete layers is located, that is, the response material is only micro-vibrated, thereby avoiding damage to the constructability of the 3D printed concrete during the vibration of the response material, introducing micro-vibration of the response material to avoid affecting the overall constructability and not causing the collapse of the 3D printed concrete. By introducing a response material that can absorb energy under microwave excitation into the polymer emulsion layer, by arranging the polymer emulsion layer between each printed layer of the 3D printed concrete and between the implanted steel bars and the concrete matrix, under the excitation of microwave energy, the response material absorbs radiation by utilizing the characteristic of absorbing radiation, thereby heating and curing the concrete between each printed layer of the concrete and in the micro-region of the steel bar-matrix, thereby evenly improving the bonding strength between each printed layer of the 3D printed concrete and between the steel bar-matrix.By setting polymer emulsion between each printed layer of 3D concrete and between the steel bars and the matrix, the interfacial tensile bonding strength and steel bar bond strength of 3D printed concrete are greatly improved; compared with 3D printed concrete set with polyacrylic acid emulsion interface agent in the prior art, its interfacial tensile bonding strength is increased by more than 1.5 times; and the steel bar bond strength is increased by more than 0.25 times.

[0025] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the preferred embodiments of the present invention are described in detail as follows. DETAILED DESCRIPTION

[0026] In order to further explain the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following is a detailed description of a concrete 3D printing method and concrete 3D printed products and their specific implementation methods, structures, features and effects proposed by the present invention in combination with the preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0027] The present invention proposes a concrete 3D printing method, which comprises the following steps: 1) printing concrete layers layer by layer; a polymer emulsion layer is arranged between two adjacent concrete layers to obtain a concrete 3D printed blank; the polymer emulsion layer comprises a response material with a particle size of less than 10 μm; 2) placing the concrete 3D printed blank in an external energy field to allow the response material to act in the external energy field.

[0028] In the above technical solution, the external energy field is preferably a magnetic field and / or a microwave field. By placing the concrete 3D printed blank in the external energy field, the response material therein vibrates under the action of the high-frequency magnetic field to produce micro-vibration and / or absorbs energy under microwave excitation to produce thermal curing.

[0029] In the present invention, microwaves and electromagnetic waves have the same meaning.

[0030] The present invention also provides a concrete 3D printed product, which includes:

[0031] N concrete layers, N is a natural number ≥ 2;

[0032] N-1 polymer emulsion layer is arranged between two adjacent concrete layers; the polymer emulsion layer includes a response material with a particle size of less than 10 μm.

[0033] In the above technical solution, the layers do not exist in isolation, but are fused into a whole through the action of the responsive material. Specifically, with the micro-vibration and / or thermal curing of the responsive material, the two adjacent layers of concrete can be fused into a whole, and the responsive material is retained between the interfaces after the micro-vibration and / or thermal curing is stopped; at the same time, the aqueous emulsion as the carrier of the responsive material, in addition to the action of micro-vibration and / or thermal curing, can also diffuse and penetrate into the two adjacent layers of concrete, so that the polymer can form a cross-linked network interconnected between the layers, thereby further improving the bonding strength of the two adjacent layers of concrete.

[0034] When the 3D printed concrete is added with a reinforcement planting method, the technical solution of the present invention further includes a reinforcement planting step between step 1) and step 2), specifically including: setting a polymer emulsion layer on the surface of the steel bar and drying; it should be noted that the drying here is surface drying rather than actual drying. The purpose of such a setting is: on the one hand, the polymer emulsion layer will not be destroyed when the steel bar is inserted into the concrete layer, and on the other hand, the polymer emulsion layer will not be actually dried to fix the response material therein, making it difficult to move in the external energy field and affecting its function. Finally, the steel bar is inserted into the concrete 3D printed blank in a direction perpendicular to the concrete layer. The concrete 3D printed product prepared by the present invention includes M implanted steel bars, M is a natural number ≥2, the number of steel bars can be set according to the process requirements, and the insertion position is not specifically limited; the surface of the implanted steel bar is also provided with the polymer emulsion layer, so that it can be micro-vibrated and / or thermally cured in the external energy field.

[0035] In the above technical solution, the layers and the steel bar-concrete matrix are fused into a whole through the action of the responsive material. With the micro-vibration and / or thermal curing of the responsive material, the concrete of the two adjacent layers and the steel bar and the concrete matrix can be fused into a whole, and the responsive material is retained between the interfaces after the micro-vibration and / or thermal curing are stopped.

[0036] In a specific embodiment of the present invention, the following steps are specifically included: printing a first concrete layer, spraying a layer of polymer emulsion on the surface of the first concrete layer to form a first polymer emulsion layer; then printing a second concrete layer on the first polymer emulsion layer, spraying a layer of polymer emulsion on the surface of the second concrete layer to form a second polymer emulsion layer; sequentially until printing the N-1th concrete layer, spraying a layer of polymer emulsion on the surface of the N-1th concrete layer to form the N-1th polymer emulsion layer, wherein N is a natural number ≥ 2; finally printing the Nth concrete layer on the N-1th polymer emulsion layer to obtain a concrete 3D printed blank including N concrete layers and N-1 polymer emulsion layers. After the concrete 3D printed blank is printed, it is placed in an external energy field so that the responsive material vibrates under the action of a high-frequency magnetic field and / or absorbs energy under microwave excitation, thereby obtaining a concrete 3D printed product with a strong bonding force between layers.

[0037] In a specific embodiment of the present invention, the following steps are specifically included: printing the first concrete layer, spraying a layer of polymer emulsion on the surface of the first concrete layer to form a first polymer emulsion layer; then printing the second concrete layer on the first polymer emulsion layer, spraying a layer of polymer emulsion on the surface of the second concrete layer to form a second polymer emulsion layer; proceeding in sequence until the N-1th concrete layer is printed, spraying a layer of polymer emulsion on the surface of the N-1th concrete layer to form the N-1th polymer emulsion layer, wherein N is a natural number ≥ 2; finally printing the Nth concrete layer on the N-1th polymer emulsion layer to obtain a concrete 3D printed blank including N concrete layers and N-1 polymer emulsion layers. Apply a polymer emulsion layer on the surface of the steel bar to be planted, dry it, and control the drying time so that the coating is only surface-drying but not actually dry, to obtain a steel bar with a polymer emulsion layer on the surface; then insert the steel bar into the concrete 3D printed blank in a direction perpendicular to the concrete printing layer. Finally, it is placed in an external energy field so that the responsive material vibrates under the action of the high-frequency magnetic field and / or absorbs energy under microwave excitation, thereby obtaining a concrete 3D printed product with strong bonding between layers and between the steel bars and the concrete matrix.

[0038] In the above technical scheme, a polymer emulsion layer is arranged between two adjacent concrete layers, and a response material with a particle size of less than 10 μm is introduced into the polymer emulsion layer, which is the key to achieving the technical effect of the present invention; wherein the response material can be a material that can vibrate under the action of a high-frequency magnetic field, that is, a first response material; or a material that can absorb energy under microwave excitation, that is, a second response material; introducing the first response material alone into the polymer emulsion layer can achieve the effect of improving the interlayer bonding force of the present invention; introducing the second response material alone into the polymer emulsion layer can also achieve the effect of improving the interlayer bonding force of the present invention; more preferably, the polymer emulsion layer includes both the first response material that can vibrate under the action of a high-frequency magnetic field and the second response material that can absorb energy under microwave excitation, and under the joint action of the two, further technical effects can be achieved; in order to optimize the bonding strength of each printed layer of the 3D printed concrete product, the present invention preferably has a mass ratio of the first response material to the second response material of 1:0.5 to 10.

[0039] In the above technical solution, the particle size of the response material needs to be strictly controlled to be less than 10μm. The reasons for strictly limiting the particle size of the response material are mainly: first, to avoid the high-frequency magnetic field from being difficult to control its movement due to the response material being too large, that is, the response material cannot respond, and thus interlayer vibration cannot be performed, and the technical effect of the present invention cannot be achieved; second, to avoid the response material being too large and making its vibration area larger, that is, controlling the response material to vibrate only in micro-areas between each printed layer of concrete, thereby avoiding a greater impact on the upper and lower layers of the concrete printing layer, and avoiding affecting the overall constructability of the 3D printed concrete and causing the collapse of the 3D printed concrete; in view of the above two considerations, for the comprehensive performance of the balancer, the present invention preferably has a particle size of the response material less than 10μm.

[0040] By arranging the polymer emulsion between each printed layer of 3D printed concrete and between the steel bar and the concrete matrix, the response material is made to vibrate at high frequency between each printed layer of concrete and at the steel bar-concrete interface under the action of the high-frequency magnetic field, so that the concrete between the layers and at the steel bar-concrete interface is vibrated and compacted, and the bonding strength between each printed layer and between the steel bar and the concrete is improved; by arranging the polymer emulsion of the present invention between each printed layer of 3D printed concrete and between the steel bar and the concrete matrix, the response material absorbs radiation under the excitation of microwave energy, so that the concrete is heated and cured in the micro-region between each printed layer of concrete and at the interface of the steel bar and the concrete matrix, thereby uniformly improving the bonding strength between each printed layer of 3D printed concrete and between the steel bar and the concrete.

[0041] In the above technical solution, the key material that can vibrate under the action of a high-frequency magnetic field and / or absorb energy under microwave excitation is the response material. However, since the response material itself is difficult to coat evenly and may agglomerate, the present invention preferably formulates the response material in the form of a polymer emulsion.

[0042] In a specific embodiment of the present invention, the polymer emulsion includes, by mass percentage: 48% to 75% aqueous emulsion, 10% to 30% response material, 5% to 15% stabilizer, 2% to 7% solubilizer and 7% to 27% water; wherein the response material can vibrate under the action of a high-frequency magnetic field and / or can absorb energy under microwave excitation.

[0043] The preparation of the above polymer emulsion includes the following steps: 1) weighing the raw materials according to the formula of the polymer emulsion; in terms of mass percentage, the polymer emulsion includes: 48% to 75% aqueous emulsion, 10% to 30% response material, 5% to 15% stabilizer and 7% to 27% water; 2) mixing the aqueous emulsion and water, and then adding the response material and stabilizer to the mixed liquid under the condition of stirring speed>10000rpm, stirring evenly, to obtain a polymer emulsion for concrete 3D printing; wherein the response material can vibrate under the action of a high-frequency magnetic field and / or can absorb energy under microwave excitation. The dispersion of the above various raw materials is mainly carried out by mechanical mixing, and the key point of its control is to add the response material to the polymer emulsion. When adding the response material, high-speed stirring is required, and the stirring speed>10000rpm can evenly disperse the raw materials.

[0044] The responsive material in the above technical solution is preferably at least one of iron powder, aluminum powder and tin powder. The iron powder is the first responsive material, which mainly vibrates under the action of a high-frequency magnetic field to generate micro-region vibration between each printed layer of concrete to improve its bonding strength; the aluminum powder and / or tin powder is the second responsive material, which mainly utilizes its energy storage characteristics to absorb and release the energy of electromagnetic waves, thereby improving the interlayer bonding between each printed layer of concrete.

[0045] In order to make the response material have good compatibility with the cement-based material so as to achieve good micro-region vibration, for example, hydroxyl can improve the hydrophilicity of the response material, carbonyl can further improve the magnetic responsiveness of the corresponding material, and carbonyl can improve the dispersibility and fluidity of the effect material. In the present invention, the iron powder is preferably selected from at least one of hydroxyl iron powder, carbon-based iron powder, carbonyl iron powder, nano iron powder and nano Fe3O4. The particle size of the nano iron powder and nano Fe3O4 is preferably <50nm.

[0046] The aqueous emulsion in the above technical solution exists mainly as a carrier of the response material. Due to the characteristics of the technical solution of the present invention, the particle size of the response material used in the present invention is determined to be less than 10μm, and the response material with a very small particle size is easy to agglomerate, so that the pure response material is evenly distributed on the surface of each printed layer of the 3D concrete. The technical solution of the present invention preferably disperses the response material in the aqueous emulsion so that the response material is better dispersed so that it can be evenly arranged on the surface of each printed layer of the 3D concrete; the aqueous emulsion can be selected from any form of emulsion that can load and disperse the response material.

[0047] In order to make it have better affinity with cement materials, the technical solution of the present invention preferably uses an aqueous emulsion; the aqueous emulsion is selected from at least one of polystyrene emulsion, polyaniline emulsion, styrene-butadiene emulsion and polyacrylic acid emulsion.

[0048] The aqueous emulsion in the above technical solution also plays a certain role in improving the bonding force between the printed layers of 3D printed concrete. The present invention introduces an aqueous emulsion into the polymer emulsion. In addition to being used as a carrier to disperse the response material, the aqueous emulsion can also penetrate into the upper and lower layers of the concrete printed layer under the synergistic effect of vibration, thereby forming a polymer network that penetrates the concrete layer, thereby enhancing the bonding force between the concrete layers and improving the bonding strength of the 3D printed concrete product.

[0049] A stabilizer is further added to the above technical solution, and the stabilizer is preferably at least one of nano-SiO2 particles, graphene nanosheets and carbon nanotubes. The stabilizer is mainly used to fill the gap between the micron-scale and nano-scale response materials, enhance Brownian motion, prevent the polymer emulsion from segregating, and thus improve the stability of the polymer emulsion.

[0050] A solubilizer is also added to the above technical solution, and the solubilizer is preferably nano CSH gel. The solubilizer is mainly used to provide adsorption points for the corresponding material, further increasing the solubility of the response material.

[0051] In order to enable the polymer emulsion layer to further improve the bonding strength between concrete layers in addition to the micro-vibration and / or heat curing of the response material, the present invention preferably designs the thickness of the concrete layer and the polymer emulsion layer to match each other, so that the aqueous emulsion in the polymer emulsion can fully penetrate into the adjacent upper and lower layers of concrete, so that the cementitious materials between the layers are interconnected to form a polymer network structure. The present invention preferably controls the mass of the single-layer polymer emulsion layer to be 0.5-1.5% of the mass of the cementitious material in the single-layer concrete layer.

[0052] In order to enable the responsive material in the polymer emulsion to fully exert micro-vibration and / or heat curing, the present invention preferably designs the surface areas of the concrete layer and the steel bars to match each other, so that the responsive material can fully vibrate and / or heat cure around the steel bars. The present invention preferably controls the coverage rate of the polymer emulsion on the steel bar surface to be ≥10%.

[0053] In order to enable concrete to be vibrated during 3D printing to achieve good density between the printed layers of concrete without affecting the constructibility and appearance of the concrete due to excessive vibration, the particle size of the response material in the technical solution of the present invention is preferably less than 10 μm; in order to match the type, content and particle size of the response material, and according to the process requirements of concrete 3D printing, the present invention preferably uses a magnetic field and / or electromagnetic waves as the external energy; the intensity of the magnetic field is 1 to 1000 KA / m, the frequency is 50 to 200 Hz, and the magnetization time is 5 to 20 min; the frequency of the electromagnetic wave is 300 MHz to 10 GHz, and the radiation time is 5 to 20 min.

[0054] Generally, the initial setting time of 3D concrete is about 2 hours, and the final setting time is 4 to 5 hours; the micro-vibration of the present invention is preferably carried out within the initial setting time.

[0055] Preferably, the direction of applying the magnetic field and / or electromagnetic wave is perpendicular to the surface of the concrete layer, so that the response material is micro-vibrated between concrete layers; the movement direction of the response material can be vertical, oblique or horizontal.

[0056] The concrete 3D printed product of the present invention can be obtained by printing through the aforementioned concrete 3D printing method of the present invention.

[0057] The concrete 3D printed product printed by the concrete 3D printing method of the present invention performs micro-vibration and / or heat curing between concrete layers and at the steel bar-concrete interface through the response material, and the polymer emulsion penetrates through the concrete layer to form a polymer network. The combined effect of multiple factors greatly improves the interlayer bonding strength of the concrete 3D printed product of the present invention; compared with the 3D printed concrete with the acrylic emulsion interface agent of the prior art, its interface tensile bonding strength is increased by more than 1.5 times; compared with the 3D printed concrete with direct rebar implantation, the steel bar gripping strength is increased by more than 0.25 times.

[0058] The present invention also proposes an application of the aforementioned concrete 3D printed product.

[0059] The present invention will be further described below in conjunction with specific embodiments, but this should not be construed as limiting the scope of protection of the present invention. Some non-essential improvements and adjustments made to the present invention by technicians in this field based on the above-mentioned contents of the present invention still fall within the scope of protection of the present invention.

[0060] Unless otherwise specified, the materials, reagents, etc. involved below are all commercially available products well known to those skilled in the art; unless otherwise specified, the methods described are all methods well known in the art. Unless otherwise defined, the technical terms or scientific terms used should have the common meanings understood by ordinary technicians in the field to which the present invention belongs.

[0061] In the embodiments of the present invention, the test was performed in accordance with the "3D Printing Concrete Basic Mechanical Properties Test Method" T / CCPA 33-2022 (T / CBMF 183).

[0062] In the embodiments of the present invention, the test is carried out in accordance with the "Test Method for Bond Strength of Cement Concrete and Steel Bars" T0566-2020.

[0063] The solid contents of the aqueous emulsions used in the following embodiments are as follows: the solid content of the polystyrene emulsion is 50%, the solid content of the styrene-butadiene emulsion is 48%, and the solid content of the polyacrylic acid emulsion is 55%, all of which are purchased commercially; the 3D printing concrete is also purchased commercially.

[0064] Example 1

[0065] The concrete 3D printing method of this embodiment is as follows:

[0066] 1) weighing raw materials according to the formula of polymer emulsion; in terms of mass percentage, the polymer emulsion includes: the response material includes hydroxyl iron powder, carbonyl iron powder and nano iron powder with a particle size of less than 10 μm, the mass ratio of the three is 2:3:5, and the response material accounts for 18% of the total weight of the polymer emulsion; the aqueous emulsion includes polystyrene emulsion and styrene butadiene emulsion, the mass ratio of the two is 4:6, and the aqueous emulsion accounts for 70% of the total weight of the polymer emulsion; the stabilizer includes nano-SiO2 particles (particle size <0.5 μm) and graphene nanosheets (sheet diameter <10 μm, thickness <10 nm), the mass ratio of the two is 7:3, and the stabilizer accounts for 5% of the total weight of the polymer emulsion; water accounts for 7% of the total weight of the polymer emulsion;

[0067] 2) Mixing the aqueous emulsion and water, adding the response material and the stabilizer to the mixed solution at a stirring speed of >10000 rpm, and stirring evenly to obtain a polymer emulsion for concrete 3D printing;

[0068] 3) Print a layer of concrete, and evenly spray a layer of polymer emulsion on its surface (the spraying amount is 0.8% of the mass of the cementitious material of this layer of concrete); print another layer of concrete (material and thickness are the same as before), and spray another layer of polymer emulsion (spraying amount is the same as before); repeat this operation until the concrete 3D printed blank is printed; the last layer is a concrete layer; it contains four layers of concrete and three layers of polymer emulsion;

[0069] 4) After the concrete 3D printed blank is printed, the magnetic field generator is turned on, the concrete 3D printed blank is placed in the magnetic field, and the 3D printed concrete component sprayed with the polymer emulsion is magnetized. The magnetic field intensity is 450KA / m, the magnetization time is 10 min, and the frequency of changing the magnetic field direction is 100 Hz to obtain a 3D printed concrete component.

[0070] After testing, the concrete interface tensile bonding strength of this embodiment is 5.5 MPa.

[0071] Comparative Example 1

[0072] The same as Example 1, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0073] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.11 MPa; compared with comparative example 1, the tensile bonding strength of the concrete interface of embodiment 1 is increased by 160%.

[0074] Example 2

[0075] The concrete 3D printing method of this embodiment is as follows:

[0076] 1) weighing raw materials according to the formula of polymer emulsion; in terms of mass percentage, the polymer emulsion includes: the response material includes hydroxyl iron powder, carbonyl iron powder and nano iron powder with a particle size of less than 10 μm, the mass ratio of the three is 3:5:2, and the response material accounts for 28% of the total weight of the polymer emulsion; the aqueous emulsion includes polystyrene emulsion, styrene butadiene emulsion and polyacrylic acid emulsion, the mass ratio of the three is 2:2:6, and the aqueous emulsion accounts for 55% of the total weight of the polymer emulsion; the stabilizer includes nano-SiO2 particles (particle size <0.5 μm) and graphene nanosheets (sheet diameter <10 μm, thickness <10 nm), the mass ratio of the two is 7:3, and the stabilizer accounts for 7% of the total weight of the polymer emulsion; water accounts for 10% of the total weight of the polymer emulsion;

[0077] 2) Mixing the aqueous emulsion and water, adding the response material and the stabilizer to the mixed solution at a stirring speed of >10000 rpm, and stirring evenly to obtain a polymer emulsion for concrete 3D printing;

[0078] 3) Print a layer of concrete, and evenly spray a layer of polymer emulsion on its surface (the spraying amount is 1.5% of the mass of the cementitious material of this layer of concrete); print another layer of concrete (material and thickness are the same as before), and spray another layer of polymer emulsion (spraying amount is the same as before); repeat this operation until the concrete 3D printed blank is printed; the last layer is a concrete layer; it contains four layers of concrete and three layers of polymer emulsion;

[0079] 4) After the concrete 3D printed blank is printed, the magnetic field generator is turned on, the concrete 3D printed blank is placed in the magnetic field, and the 3D printed concrete component sprayed with the polymer emulsion is magnetized. The magnetic field intensity is 550KA / m, the magnetization time is 15min, and the frequency of changing the magnetic field direction is 150Hz to obtain a 3D printed concrete component.

[0080] After testing, the concrete interface tensile bonding strength of this embodiment is 5.87 MPa.

[0081] Comparative Example 2

[0082] The same as Example 2, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0083] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.11 MPa; compared with comparative example 2, the tensile bonding strength of the concrete interface of embodiment 2 is increased by 178%.

[0084] Example 3

[0085] The concrete 3D printing method of this embodiment is as follows:

[0086] 1) weighing raw materials according to the formula of polymer emulsion; in terms of mass percentage, the polymer emulsion includes: the response material includes hydroxy iron powder, aluminum powder and tin powder with a particle size of less than 10 μm, the mass ratio of the three is 3:5:2, and the response material accounts for 15% of the total weight of the polymer emulsion; the aqueous emulsion includes polystyrene emulsion, styrene butadiene emulsion and polyacrylic acid emulsion, the mass ratio of the three is 4:2:4, and the aqueous emulsion accounts for 65% of the total weight of the polymer emulsion; the stabilizer includes nano-SiO2 particles (particle size <0.5 μm), graphene nanosheets (sheet diameter <10 μm, thickness <10 nm) and carbon nanotubes (diameter <15 nm), the mass ratio of the three is 4:4:2, and the stabilizer accounts for 5% of the total weight of the polymer emulsion; water accounts for 15% of the total weight of the polymer emulsion;

[0087] 2) Mixing the aqueous emulsion and water, adding the response material and the stabilizer to the mixed solution at a stirring speed of >10000 rpm, and stirring evenly to obtain a polymer emulsion for concrete 3D printing;

[0088] 3) Print a layer of concrete, and evenly spray a layer of polymer emulsion on its surface (the spraying amount is 1.2% of the mass of the cementitious material of this layer of concrete); print another layer of concrete (material and thickness are the same as before), and spray another layer of polymer emulsion (spraying amount is the same as before); repeat this operation until the concrete 3D printed blank is printed; the last layer is a concrete layer; it contains four layers of concrete and three layers of polymer emulsion;

[0089] 4) After the concrete 3D printed blank is printed, the microwave generator is turned on, the concrete 3D printed blank is placed in the microwave generator, and the 3D printed concrete component sprayed with the polymer emulsion is subjected to microwave treatment, the microwave frequency is 1000 KHz, and the radiation time is 15 min to obtain a 3D printed concrete component.

[0090] After testing, the concrete interface tensile bonding strength of this embodiment is 7.5 MPa.

[0091] Comparative Example 3

[0092] Same as Example 3, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0093] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.75 MPa; compared with comparative example 3, the tensile bonding strength of the concrete interface of embodiment 3 is increased by 173%.

[0094] Example 4

[0095] Same as Example 1, except that the response material accounts for 10% of the total weight of the polymer emulsion; the aqueous emulsion accounts for 50% of the total weight of the polymer emulsion; the stabilizer accounts for 13% of the total weight of the polymer emulsion; water accounts for 27% of the total weight of the polymer emulsion; the printed part is magnetized, the magnetic field intensity is 900KA / m, the magnetization time is 15min, and the frequency of changing the magnetic field direction is 150Hz.

[0096] After testing, the concrete interface tensile bonding strength of this embodiment is 5.8 MPa.

[0097] Comparative Example 4

[0098] Same as Example 4, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0099] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.11 MPa; compared with comparative example 4, the tensile bonding strength of the concrete interface of embodiment 4 is increased by 175%.

[0100] Example 5

[0101] Same as Example 2, except that the response material accounts for 13% of the total weight of the polymer emulsion; the aqueous emulsion accounts for 75% of the total weight of the polymer emulsion; the stabilizer accounts for 5% of the total weight of the polymer emulsion; water accounts for 7% of the total weight of the polymer emulsion; the printed part is magnetized, the magnetic field intensity is 1000KA / m, the magnetization time is 8 minutes, and the frequency of changing the magnetic field direction is 200Hz.

[0102] After testing, the tensile bonding strength of the concrete interface of this embodiment is 5.9 MPa.

[0103] Comparative Example 5

[0104] Same as Example 5, except that the interface agent used was a commercially purchased polyacrylic acid emulsion;

[0105] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.11 MPa; compared with comparative example 5, the tensile bonding strength of the concrete interface of embodiment 5 is increased by 180%.

[0106] Example 6

[0107] Same as Example 3, except that the response material accounts for 30% of the total weight of the polymer emulsion; the aqueous emulsion accounts for 48% of the total weight of the polymer emulsion; the stabilizer accounts for 15% of the total weight of the polymer emulsion; water accounts for 7% of the total weight of the polymer emulsion; the printed part is magnetized, the magnetic field intensity is 630KA / m, the magnetization time is 7.5min, and the frequency of changing the magnetic field direction is 135Hz.

[0108] After testing, the concrete interface tensile bonding strength of this embodiment is 7.25 MPa.

[0109] Comparative Example 6

[0110] Same as Example 6, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0111] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.75 MPa; compared with comparative example 6, the tensile bonding strength of the concrete interface of embodiment 6 is increased by 164%.

[0112] Example 7

[0113] Same as Example 3, except that the response material includes aluminum powder and tin powder with a particle size of less than 10 μm, and the mass ratio of the two is 5:5; the printed part is subjected to microwave treatment, the microwave frequency is 750 KHz, and the radiation time is 10 minutes.

[0114] After testing, the concrete interface tensile bonding strength of this embodiment is 6.9 MPa.

[0115] Comparative Example 7

[0116] Same as Example 7, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0117] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.65 MPa; compared with comparative example 7, the tensile bonding strength of the concrete interface of embodiment 7 is increased by 160%.

[0118] Example 8

[0119] Same as Example 3, except that the response material includes aluminum powder and tin powder with a particle size of less than 10 μm, and the mass ratio of the two is 5:5; the printed part is magnetized and microwave treated in sequence, the magnetic field intensity is 630KA / m, the magnetization time is 7.5 minutes, and the frequency of changing the magnetic field direction is 135Hz; the microwave frequency is 750KHz, and the radiation time is 10 minutes.

[0120] After testing, the concrete interface tensile bonding strength of this embodiment is 9.5 MPa.

[0121] Comparative Example 8

[0122] Same as Example 8, except that the interface agent used is a commercially purchased polyacrylic acid emulsion.

[0123] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.78 MPa; compared with comparative example 7, the tensile bonding strength of the concrete interface of embodiment 7 is increased by 242%.

[0124] Example 9

[0125] The polymer emulsion slurry preparation method of this embodiment is as follows:

[0126] 1) Weighing raw materials according to the formula of polymer emulsion slurry; in terms of mass percentage, the polymer emulsion slurry includes: the response material includes hydroxy iron powder, aluminum powder and tin powder with a particle size of less than 10 μm, the mass ratio of the three is 3:5:2, and the response material accounts for 15% of the total weight of the polymer emulsion slurry; the aqueous emulsion includes polystyrene emulsion, styrene butadiene emulsion and polyacrylic acid emulsion, the mass ratio of the three is 4:2:4, and the aqueous emulsion accounts for 65% of the total weight of the polymer emulsion slurry; the stabilizer includes nano-SiO2 particles (particle size <0.5 μm), graphene nanosheets (sheet diameter <10 μm, thickness <10 nm) and carbon nanotubes (diameter <15 nm) in a mass ratio of 4:4:2, and the stabilizer accounts for 5% of the total weight of the polymer emulsion slurry; the solubilizer is CSH gel with a particle size of less than 0.3 μm, accounting for 3.5% of the total mass of the polymer emulsion slurry, and water accounts for 11.5% of the total weight of the polymer emulsion slurry;

[0127] 2) Mixing the aqueous emulsion and water, adding the response material and the stabilizer to the mixture at a stirring speed of >10000 rpm, and stirring evenly to obtain a polymer emulsion slurry for concrete 3D printing;

[0128] 3) Print a layer of concrete, and evenly spray a layer of polymer emulsion slurry on its surface, the spraying amount is 1.5% of the mass of the cementitious material used in this layer of concrete; print another layer of concrete (material and thickness are the same as before), and spray another layer of polymer emulsion slurry (spraying amount is the same as before); repeat this operation until the 3D printed concrete product is printed; the last layer is a concrete layer; it contains four layers of concrete and three layers of polymer emulsion;

[0129] 4) After printing is completed, turn on the microwave generator, place the printed part in the microwave generator, and perform microwave treatment on the 3D printed concrete component sprayed with the polymer emulsion slurry. The microwave frequency of the polymer emulsion slurry is 1000KHz, and the radiation time is 15min.

[0130] After testing, the concrete interface tensile bonding strength of this embodiment is 7.9 MPa.

[0131] Comparative Example 9

[0132] Same as Example 9, except that the interfacial agent used is a commercially purchased polyacrylic acid emulsion.

[0133] After testing, the tensile bonding strength of the concrete interface of this comparative example is 2.75 MPa; compared with comparative example 9, the tensile bonding strength of the concrete interface of embodiment 9 is increased by 187%.

[0134] It can be seen from the test data of the above embodiments and comparative examples that the interfacial tensile bonding strength of the concrete 3D printed products obtained by the concrete 3D printing method of the present invention is ≥5MPa, and its bonding strength is increased by more than 1.5 times compared with the interface agent in the prior art; in particular, when a suitable response material is added and magnetization treatment and microwave treatment are performed at the same time, its strength can be further increased to more than 9MPa, and its bonding strength is increased by more than 2.4 times; when a compatibilizer is added to the polymer emulsion formula, its effect on improving the interfacial bonding strength is particularly obvious.

[0135] Example 10

[0136] The concrete 3D printing method of this embodiment is as follows:

[0137] 1) weighing raw materials according to the formula of polymer emulsion; in terms of mass percentage, the polymer emulsion includes: the response material includes hydroxyl iron powder, carbonyl iron powder and nano iron powder with a particle size of less than 10 μm, the mass ratio of the three is 2:3:5, and the response material accounts for 18% of the total weight of the polymer emulsion; the aqueous emulsion includes polystyrene emulsion and styrene butadiene emulsion, the mass ratio of the two is 4:6, and the aqueous emulsion accounts for 70% of the total weight of the polymer emulsion; the stabilizer includes nano SiO2 particles (particle size <0.5 μm) and graphene nanosheets (sheet diameter <10 μm, thickness <10 nm), the mass ratio of the two is 7:3, and the stabilizer accounts for 5% of the total weight of the polymer emulsion; the solubilizer is nano CSH, accounting for 2% of the total mass of the total polymer emulsion, and water accounts for 5% of the total weight of the polymer emulsion;

[0138] 2) Mixing the aqueous emulsion and water, adding the response material and the stabilizer to the mixture at a stirring speed of >10000 rpm, and stirring evenly to obtain a polymer emulsion for concrete 3D printing; spraying the steel bars (the steel bars have a diameter of 15 mm and a length of 6 cm) to be embedded in the concrete, so that the coverage rate of the polymer emulsion on the steel bar surface is 50%;

[0139] 3) Print a layer of concrete, and evenly spray a layer of polymer emulsion on its surface (the spraying amount is 0.8% of the mass of the cementitious material of this layer of concrete); print another layer of concrete (material and thickness are the same as before), and spray another layer of polymer emulsion (spraying amount is the same as before); repeat this operation until the concrete 3D printed blank is printed; the last layer is a concrete layer; it contains four layers of concrete and three layers of polymer emulsion;

[0140] 4) Inserting the steel bars sprayed with the polymer emulsion layer into the 3D printed concrete blank in a direction perpendicular to the concrete printing surface, inserting a total of 6 steel bars, and arranging the steel bars in a 2×3 matrix;

[0141] 5) After the reinforcement is planted, turn on the magnetic field generator, place the concrete 3D printed blank in the magnetic field, and magnetize the 3D printed concrete component with reinforcement sprayed with polymer emulsion. The magnetic field intensity is 450KA / m, the magnetization time is 10 min, and the frequency of changing the magnetic field direction is 100 Hz to obtain a 3D printed concrete component.

[0142] According to the test, the bond strength of the concrete reinforcement in this embodiment is 15.5 MPa.

[0143] Comparative Example 10

[0144] Same as Example 10, except that the polymer emulsion is not sprayed onto the steel bars.

[0145] After testing, the bond strength of the reinforced concrete in this comparative example is 12 MPa; compared with comparative example 10, the bond strength of the concrete and reinforced concrete in embodiment 10 is increased by 29.2%.

[0146] The technical features in the claims and / or the specification of the present invention may be combined, and the combination is not limited to the combination obtained by reference in the claims. The technical solution obtained by combining the technical features in the claims and / or the specification is also within the protection scope of the present invention.

[0147] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Any simple modification, equivalent change and modification made to the above embodiment according to the technical essence of the present invention still falls within the scope of the technical solution of the present invention.

Claims

1. A concrete 3D printing method, characterized in that: It includes the following steps: 1) Printing concrete layers layer by layer; a polymer emulsion layer is provided between two adjacent concrete layers to obtain a concrete 3D printed blank; the polymer emulsion layer includes a response material with a particle size of less than 10 μm; 2) placing the concrete 3D printed blank in an external energy field, so that the responsive material acts in the external energy field.

2. The concrete 3D printing method according to claim 1, characterized in that: The step of planting reinforcement bars is also included between step 1) and step 2), which specifically includes: Setting a polymer emulsion layer on the steel bar surface and drying it; The steel bar is inserted into the concrete 3D printed blank in a direction perpendicular to the concrete layer.

3. The concrete 3D printing method according to claim 2, characterized in that: The polymer emulsion layer arranged between two adjacent concrete layers is formed by spraying the polymer emulsion slurry; the polymer emulsion layer arranged on the surface of the steel bar is formed by dipping or coating the polymer emulsion slurry.

4. The concrete 3D printing method according to any one of claims 1 to 3, characterized in that: The response material is selected from at least one of iron powder, aluminum powder and tin powder; the iron powder is selected from at least one of hydroxyl iron powder, carbon-based iron powder, carbonyl iron powder, nano iron powder and nano Fe3O4.

5. The concrete 3D printing method according to any one of claims 1 to 3, characterized in that: The response material includes a first response material and a second response material; the first response material can vibrate under the action of a high-frequency magnetic field; the second response material can absorb energy under microwave excitation; the first response material is selected from at least one of hydroxyl iron powder, carbon-based iron powder, carbonyl iron powder, nano iron powder and nano Fe3O4; the second response material is selected from aluminum powder and / or tin powder; the mass ratio of the first response material to the second response material is 1:0.5~10.

6. The concrete 3D printing method according to any one of claims 1 to 3, characterized in that: The mass of the single polymer emulsion layer arranged between two adjacent concrete layers is 0.5-1.5% of the mass of the cementitious material in the single concrete layer; the coverage rate of the polymer emulsion layer arranged on the steel bar surface to the steel bar surface is ≥10%.

7. The concrete 3D printing method according to claim 1, characterized in that: The external energy field is a magnetic field and / or an electromagnetic wave; the intensity of the magnetic field is 1 to 1000 KA / m, the frequency is 50 to 200 Hz, and the magnetization time is 5 to 20 minutes; the frequency of the electromagnetic wave is 300 MHz to 10 GHz, and the radiation time is 5 to 20 minutes; the direction in which the magnetic field and / or electromagnetic wave is applied is perpendicular to the surface of the concrete layer.

8. A concrete 3D printed product, characterized in that: It includes: N concrete layers, N is a natural number ≥ 2; N-1 polymer emulsion layer is arranged between two adjacent concrete layers; the polymer emulsion layer includes a response material with a particle size of less than 10 μm.

9. The concrete 3D printed product according to claim 8, characterized in that: It also includes M implanted steel bars, where M is a natural number ≥ 2; the surface of the implanted steel bars is also provided with the polymer emulsion layer.

10. An application of the concrete 3D printed product according to claim 8 or 9.