CN111302718B - Method for preparing 3D printing concrete from commercial concrete on site - Google Patents
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- CN111302718B CN111302718B CN202010249721.1A CN202010249721A CN111302718B CN 111302718 B CN111302718 B CN 111302718B CN 202010249721 A CN202010249721 A CN 202010249721A CN 111302718 B CN111302718 B CN 111302718B
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/04—Portland cements
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B28—WORKING CEMENT, CLAY, OR STONE
- B28B—SHAPING CLAY OR OTHER CERAMIC COMPOSITIONS; SHAPING SLAG; SHAPING MIXTURES CONTAINING CEMENTITIOUS MATERIAL, e.g. PLASTER
- B28B1/00—Producing shaped prefabricated articles from the material
- B28B1/001—Rapid manufacturing of 3D objects by additive depositing, agglomerating or laminating of material
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B33—ADDITIVE MANUFACTURING TECHNOLOGY
- B33Y—ADDITIVE MANUFACTURING, i.e. MANUFACTURING OF THREE-DIMENSIONAL [3-D] OBJECTS BY ADDITIVE DEPOSITION, ADDITIVE AGGLOMERATION OR ADDITIVE LAYERING, e.g. BY 3-D PRINTING, STEREOLITHOGRAPHY OR SELECTIVE LASER SINTERING
- B33Y70/00—Materials specially adapted for additive manufacturing
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
-
- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B28/00—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements
- C04B28/02—Compositions of mortars, concrete or artificial stone, containing inorganic binders or the reaction product of an inorganic and an organic binder, e.g. polycarboxylate cements containing hydraulic cements other than calcium sulfates
- C04B28/08—Slag cements
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B40/00—Processes, in general, for influencing or modifying the properties of mortars, concrete or artificial stone compositions, e.g. their setting or hardening ability
- C04B40/0028—Aspects relating to the mixing step of the mortar preparation
- C04B40/0039—Premixtures of ingredients
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- C—CHEMISTRY; METALLURGY
- C04—CEMENTS; CONCRETE; ARTIFICIAL STONE; CERAMICS; REFRACTORIES
- C04B—LIME, MAGNESIA; SLAG; CEMENTS; COMPOSITIONS THEREOF, e.g. MORTARS, CONCRETE OR LIKE BUILDING MATERIALS; ARTIFICIAL STONE; CERAMICS; REFRACTORIES; TREATMENT OF NATURAL STONE
- C04B2201/00—Mortars, concrete or artificial stone characterised by specific physical values
- C04B2201/50—Mortars, concrete or artificial stone characterised by specific physical values for the mechanical strength
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
- Y02W30/00—Technologies for solid waste management
- Y02W30/50—Reuse, recycling or recovery technologies
- Y02W30/91—Use of waste materials as fillers for mortars or concrete
Abstract
The invention relates to the field of building 3D printing and waste recycling, in particular to a method for preparing 3D printing concrete from commercial concrete on site. Firstly, a special additive for 3D printing concrete is disclosed, which comprises the following components in parts by weight: 0.5-2 parts of cellulose ether, 0-2 parts of defoaming agent, 0.1-2 parts of polyacrylamide, 0.1-3 parts of accelerating agent, 0.1-3 parts of early strength agent and 1-5 parts of attapulgite. The working performance of commercial concrete can be regulated and controlled on site by adding the special additive, so that the commercial concrete can meet the requirement of printability. In addition, the preparation process of the 3D printing concrete is simple, industrial production is easy, mass application of the 3D printing concrete is promoted, and the preparation method has practical engineering significance.
Description
Technical Field
The invention relates to the field of building 3D printing and waste recycling, in particular to a method for preparing 3D printing concrete from commercial concrete on site.
Background
In recent years, the industrialization process of China is accelerated, and the synchronous development of 'promoting novel industrialization, informatization, urbanization and agriculture modernization' becomes a basic national policy. Building industrialization has also developed rapidly in recent years as part of the industrial process. The 3D printing technology is used as one of intelligent production modes, and can reduce manual labor force, accelerate production speed and reduce waste amount of concrete when being used in the construction industry, thereby greatly accelerating the development process of building industrialization. At present, most of materials used in 3D printing buildings developed at home and abroad are 3D printing mortar, and the aggregate particle size is small. This is due, on the one hand, to the small size of the extrusion orifices of the printers currently used, which do not allow the printing of coarse aggregate concrete, and, on the other hand, to the higher homogeneity and better control of the properties of the mortar with respect to the concrete. However, in practical engineering, concrete is the building material with the largest use amount, and has better long-term performance and lower manufacturing cost compared with mortar. Therefore, realizing the printing of the concrete material containing the coarse aggregate is an urgent requirement for the application of the 3D printing technology in the construction industry.
For 3D printing mortar, the consumption is small at present, and a method of mixing dry powder mortar on a construction site is mostly adopted. However, for 3D printed concrete, when used in large amounts, it cannot be mixed in large batches on site like dry mortar due to limited site conditions and environmental evaluation requirements. Therefore, the main formulation and transportation of 3D printed concrete should be like commercial concrete. On the other hand, the workability requirement of the 3D printing concrete technology on concrete in a fresh mixing state is greatly different from that of common concrete, and the concrete is required to have certain fluidity before extrusion to ensure that the concrete can be pumped and extruded, and to have constructability in a short time after extrusion, that is, to have a rapid hardening speed and strength increase to ensure that the printed concrete has sufficient strength to bear self load and upper load brought by subsequent printing. Therefore, the workability requirements of the 3D printed concrete in two stages before and after extrusion are greatly different, theoretically, the workability optimization in different stages can be realized by adding additives, for example, the fluidity required by the 3D printed concrete before extrusion can be met by adding a water reducing agent, the slump and the setting time of the 3D printed concrete after extrusion can be controlled by adding a thickening agent, an accelerating agent and the like, and the constructability of the 3D printed concrete can be ensured. However, the working performance of concrete before and after extrusion cannot be accurately controlled by adding various additives at present, for example, the increase of a water reducing agent can reduce the constructability after extrusion, and the addition of an accelerating agent seriously influences the transportation and pumping of commercial concrete. Thus, the application of 3D printed concrete derived from commercial concrete presents a significant challenge.
Disclosure of Invention
In view of the above disadvantages of the prior art, the present invention aims to provide a method for preparing 3D printed concrete on site by using commercial concrete, which can firstly obtain commercial concrete with satisfactory working performance and meet the pumping requirements, transport the commercial concrete to the construction site, then pump the commercial concrete into a secondary mixing container, and prepare the commercial concrete into 3D printed concrete on site by adding 3D printed concrete special additives. Compared with the prior art, the method can meet different requirements of the 3D printed concrete on the working performance before and after extrusion, solves the production and transportation problems of the 3D printed concrete, can avoid the problems of field raw material stacking and environmental protection brought by mass production of the 3D printed concrete, has simple process, is beneficial to promoting mass application of the 3D printed concrete, and has practical engineering significance.
Specifically, the technical scheme of the invention is as follows:
in view of the above disadvantages of the prior art, the present invention provides a method for preparing 3D printed concrete on site by using commercial concrete, which comprises obtaining commercial concrete with satisfactory working performance, transporting the commercial concrete to a construction site, pumping the commercial concrete to a secondary mixing container, and preparing the commercial concrete into 3D printed concrete on site by adding 3D printed concrete special additive. Compared with the prior art, the method can meet different requirements of the 3D printed concrete on the working performance before and after extrusion, solves the production and transportation problems of the 3D printed concrete, can avoid the problems of field raw material stacking and environmental protection brought by mass production of the 3D printed concrete, has simple process, is beneficial to promoting mass application of the 3D printed concrete, and has practical engineering significance.
Specifically, the technical scheme of the invention is as follows:
the invention discloses a special additive for 3D printing concrete, which comprises the following components in parts by weight:
0.5 to 2 portions of cellulose ether,
0-2 parts of a defoaming agent,
0.1 to 2 portions of polyacrylamide,
0.1 to 3 portions of accelerating agent,
0.1 to 3 portions of early strength agent,
1-5 parts of attapulgite.
Preferably, the special admixture comprises the following condition 1) and at least one of 2) to 6):
1) the cellulose ether is carboxymethyl cellulose ether or lignocellulose ether;
2) the defoamer is a defoamer special for concrete;
3) the polyacrylamide is used for concrete, and the molecular weight is between 300-1000 ten thousand;
4) the accelerator is an alkali-free accelerator;
5) the early strength agent is an organic or compound early strength agent for concrete;
6) the attapulgite is nano purified attapulgite clay powder for concrete.
The invention discloses 3D printing concrete in a second aspect, and the 3D printing concrete comprises the special additive.
Preferably, the 3D printed concrete further comprises commercial concrete.
More preferably, the commercial concrete comprises the following components in parts by weight:
80-120 parts of natural macadam,
80-150 parts of river sand,
20-50 parts of a recycled coarse aggregate,
50-100 parts of cement, namely, cement,
10-40 parts of an active admixture,
0.5 to 2 portions of fiber,
0.25 to 2 portions of water reducing agent,
15-50 parts of water.
Preferably, the commercial concrete satisfies the following conditions:
1) the natural macadam is in continuous gradation, and the particle size of the natural macadam is 5-15 mm;
2) the river sand is continuous graded medium sand or fine sand, the fineness modulus is 3.0-1.6, and the particle size is 0.15-4.75 mm;
3) the recycled coarse aggregate is derived from waste concrete, is obtained by crushing and screening, and has the particle size of 5-15 mm;
4) the cement is selected from one or more of portland cement, slag cement, volcanic ash cement and fly ash cement;
5) the active admixture is selected from one or more of silica fume, fly ash, slag powder and metakaolin;
6) the fiber is selected from one or two of polyethylene fiber, polypropylene fiber and plant fiber, and the fiber length is 5-20 mm;
7) the water reducing agent is a polycarboxylic acid type water reducing agent.
In some embodiments of the invention, the recycled coarse aggregate has a water absorption of 3% to 8%, which is much higher than natural crushed stone. The water absorption of the recycled coarse aggregate is particularly considered in the preparation process of 3D printing concrete prepared by commercial concrete on site.
If the amounts of the cementing material, the natural macadam and the water in a commercial concrete formulation without the recycled coarse aggregate are respectively a, b and c, after m% of the natural macadam is replaced by the recycled coarse aggregate, and if the difference between the water absorption rates of the recycled coarse aggregate and the natural macadam is n%, the water consumption in the commercial concrete formulation is changed into W ═ c + b ×% m% n%, and meanwhile, the water-cement ratio in the formulation is changed into (c + b ×% m% n%)/a from c/a.
The third aspect of the invention discloses a method for preparing the 3D printing concrete, and the 3D printing concrete is prepared by mixing commercial concrete and a special additive on site.
Preferably, commercial concrete with working performance meeting the pumping requirement is prepared by a mixing plant, transported to a construction site and pumped into a secondary mixing container, and the 3D printing concrete meeting the printing requirement is obtained by adding a special additive and blending on site.
In some embodiments of the invention, the additive is used by weighing raw materials, mixing the raw materials together, stirring the mixture until the mixture is uniform, adding the mixture into commercial concrete pumped into a secondary stirring container, and starting stirring for 5 to 10 minutes to obtain 3D printing concrete meeting the printing requirement.
More preferably, the capacity of the secondary stirring container is 100-1000L, the power is 5-40kw, the stirring speed is 20-150rpm, and the stirring time is 5-10 minutes.
Preferably, after the commercial concrete is prepared and transported to a construction site at the mixing station, the slump of the commercial concrete reaches the requirements of 120-200mm, and the commercial concrete can be pumped on site.
Preferably, the special additive is obtained by weighing raw materials and then uniformly mixing and stirring the raw materials.
Preferably, the special additive is added into commercial concrete for secondary stirring; the weight ratio of the special additive to the gelled material is 1/100-5/100; the cementing material is cement and an active admixture in commercial concrete.
On the basis of the common general knowledge in the field, the above preferred conditions can be combined arbitrarily without departing from the concept and the protection scope of the invention.
Compared with the prior art, the invention has the following remarkable advantages and effects:
(1) the commercial concrete which can be transported in a long distance and can serve for 3D printing construction is prepared, and the transportation problem of the existing 3D printing concrete is solved;
(2) the invention develops a special additive for 3D printing commercial concrete, and the working performance of the commercial concrete can be regulated and controlled on site by adding the additive, so that the commercial concrete meets the requirement of printability;
(3) the preparation process of the 3D printing concrete is simple, the industrial production is easy, the mass application of the 3D printing concrete is promoted, and the preparation method has practical engineering significance.
Drawings
Fig. 1 is a schematic diagram of a method for preparing 3D printed concrete on site by using commercial concrete according to an embodiment of the present invention.
Detailed Description
The technical solutions of the present invention are described in detail below with reference to the drawings and embodiments, but the present invention is not limited to the scope of the embodiments.
The experimental methods without specifying specific conditions in the following examples were selected according to the conventional methods and conditions, or according to the commercial instructions. The reagents and starting materials used in the present invention are commercially available.
Example 1
A preparation method for preparing 3D printing concrete by using commercial concrete on site comprises the following steps:
preparing commercial concrete, wherein the commercial concrete comprises the following components in parts by weight: 120 parts of broken stone, 150 parts of river sand, 23.6 parts of recycled coarse aggregate, 99 parts of cement, 17.8 parts of active admixture, 0.5 part of fiber, 0.36 part of water reducing agent and 40 parts of water.
The natural macadam is characterized in that the particle size of the natural macadam is 5-15mm, the particle size of the river sand is 0.15-4.75mm, the fineness modulus is 2.2, the recycled coarse aggregate is particles obtained by crushing building wastes into particles with the particle size of 5-15mm, the water absorption rate is 3% -8%, the cement is P.O 42.5.5 ordinary portland cement, the active admixture is silica fume, the fiber is polyethylene fiber and contains various lengths of 5-20mm and the like, the water reducing agent is a polycarboxylic acid water reducing agent, and the water is tap water.
And step two, transporting the prepared commercial concrete to a construction site, testing the slump of the commercial concrete on the construction site, judging whether the pumping requirement is met, and pumping the commercial concrete to a concrete secondary mixing container.
Preparing a special additive for 3D printing concrete, wherein the special additive comprises the following components in parts by weight: 1.0 part of cellulose ether, 0.85 part of defoaming agent, 0.6 part of polyacrylamide, 0.4 part of accelerating agent, 1.2 parts of early strength agent and 3.0 parts of attapulgite, weighing all the raw materials, mixing the raw materials together, uniformly stirring the raw materials, and then adding 3% by mass of a cementing material, namely cement and an active admixture in commercial concrete, into the commercial concrete in a secondary concrete stirring container;
the cellulose ether is carboxymethyl cellulose or lignocellulose, the defoamer is a special defoamer for concrete, the polyacrylamide is polyacrylamide for concrete, the accelerator is an alkali-free accelerator, the early strength agent is an organic or compound early strength agent for concrete, and the attapulgite is nano purified attapulgite clay powder for concrete.
And step four, adjusting the stirring speed of the concrete secondary stirring container to be 20-150rpm, and stirring for 5-10 minutes to obtain the 3D printing concrete.
As shown in fig. 1, the 3D printed concrete was evaluated for extrudability and constructability and then transferred to a concrete 3D printer for concrete printing. And (3) printing layer by adopting a 3D printer according to a specifically set programming program to obtain a member sample of the 3D printing concrete prepared on site by utilizing the commercial concrete. And curing the samples in a standard curing mode, wherein the temperature of standard curing is 18-22 ℃, the humidity of standard curing is 90-95%, the curing age of standard curing is 28 days, performing anisotropic compression tests on the samples, and selecting the maximum value, wherein the maximum value is shown in table 1.
Example 2
A preparation method for preparing 3D printing concrete by using commercial concrete on site comprises the following steps:
preparing commercial concrete, wherein the commercial concrete comprises the following components in parts by weight: 100 parts of crushed stone, 108 parts of river sand, 27.5 parts of recycled coarse aggregate, 64.5 parts of cement, 27.75 parts of active admixture, 0.8 part of fiber, 0.55 part of water reducing agent and 32.3 parts of water.
The gravel is 5-15mm in particle size, the river sand is 0.15-4.75mm in particle size, the fineness modulus is 1.8, the recycled coarse aggregate is particles obtained by crushing building waste into particles with particle size of 5-15mm, the water absorption rate of the recycled coarse aggregate is 3-8%, the cement is P.O 42.5.5 ordinary portland cement, the active admixture is fly ash, the fiber is polyethylene fiber and is 6mm in length, the water reducing agent is a polycarboxylic acid water reducing agent, and the water is tap water.
And step two, transporting the prepared commercial concrete to a construction site, testing the slump of the commercial concrete on the construction site, judging whether the slump meets the pumping requirement, and pumping the commercial concrete to a concrete secondary mixing container.
Preparing a special additive for 3D printing concrete, wherein the special additive comprises the following components in parts by weight: 1.85 parts of cellulose ether, 1.5 parts of defoaming agent, 0.8 part of polyacrylamide, 0.65 part of accelerating agent, 1.2 parts of early strength agent and 3.78 parts of attapulgite, weighing all the raw materials, mixing the raw materials together, uniformly stirring the mixture, and then adding a 3D printing concrete special additive with the mass of 2.8% of that of a cementing material into commercial concrete in a concrete secondary stirring container, wherein the cementing material is cement and an active admixture in the commercial concrete;
wherein, the cellulose ether is carboxymethyl cellulose or lignocellulose, the defoamer is a defoamer special for concrete, the polyacrylamide is polyacrylamide for concrete, the accelerator is an alkali-free accelerator, the early strength agent is an organic or compound early strength agent for concrete, and the attapulgite is nano purified attapulgite clay powder for concrete.
And step four, adjusting the stirring speed of the concrete secondary stirring container to be 20-150rpm, and stirring for 5-10 minutes to obtain the 3D printing concrete.
The 3D printed concrete was evaluated for extrudability and constructability and then transported to a concrete 3D printer for concrete printing. And (3) printing layer by adopting a 3D printer according to a specifically set programming program to obtain a member sample of the 3D printing concrete prepared on site by utilizing the commercial concrete. And the samples are maintained in a standard maintenance mode, the temperature of the standard maintenance is 18-22 ℃, the humidity of the standard maintenance is 90-95%, the maintenance age of the standard maintenance is 28 days, the samples are subjected to an anisotropic compression test, and the maximum value is selected as shown in table 1.
Comparative example 1
The 3D printing concrete for the common building comprises the following components in parts by weight: 495 parts of cement, 89 parts of fly ash, 1069 parts of river sand, 765 parts of crushed stone, 118 parts of recycled coarse aggregate, 1.5 parts of cellulose ether, 3.5 parts of water reducing agent, 3.5 parts of attapulgite, 0.5 part of sodium gluconate, 0.6 part of accelerator and 233.6 parts of water. Wherein, the cement is P.O 42.5.5 ordinary portland cement; the particle size of the broken stone is 5-15mm, the particle size of the river sand is 0.15-4.75mm, the fineness modulus is 2.3, the regenerated coarse aggregate is particles obtained by crushing building waste into particles with the particle size of 5-15mm, the water absorption rate of the regenerated coarse aggregate is 3-8%, the cellulose ether is carboxymethyl cellulose or lignocellulose, the water reducing agent is a polycarboxylic acid water reducing agent, the sodium gluconate is sodium gluconate for concrete, the attapulgite is nano purified attapulgite powder for concrete, the accelerating agent is an alkali-free accelerating agent, and the water is common tap water. The preparation method of the common building 3D printing concrete comprises the following steps: step one, mixing and stirring cement, fly ash, river sand, broken stone, recycled coarse aggregate, cellulose ether, a water reducing agent, sodium gluconate, attapulgite and an accelerating agent to be uniform; and step two, mixing the mixture obtained in the step one with water and uniformly stirring to obtain the common building 3D printing concrete. Wherein, in the first step and the second step, the stirring speed is 20-150rpm, and the stirring time is 5-10 minutes. The slump of the 3D printing concrete of the common building is tested, the pumpability of the concrete is evaluated, the extrudability and the constructability of the concrete are evaluated, and the concrete is conveyed to a 3D printer for concrete printing. Printing layer by using a 3D printer according to a specifically set programming program, maintaining the samples in a standard maintenance mode, wherein the temperature of the standard maintenance is 18-22 ℃, the humidity of the standard maintenance is 90% -95%, the maintenance age of the standard maintenance is 28 days, performing anisotropic compression tests on the samples, and selecting the maximum value, wherein the maximum value is shown in Table 1.
TABLE 13D printed concrete Performance test results
In conclusion, the invention provides a preparation method for preparing 3D printing concrete by utilizing commercial concrete on site, which comprises the steps of firstly preparing the commercial concrete with working performance meeting pumping requirements, transporting the commercial concrete to a construction site, and adding 3D printing concrete admixture to prepare the commercial concrete into the concrete for 3D printing on site, so that the commercial concrete meets the requirements of building 3D printing ink pumpability, extrudability and constructability; compared with the prior art, the method can solve the transportation problem of the 3D printed concrete through the transportation of the commercial concrete, can also avoid the field stirring problem when the 3D printed concrete is applied in a large batch, has simple process, is beneficial to promoting the large-batch application of the 3D printed concrete, and has practical engineering significance; meanwhile, the 3D printing concrete uses the fly ash and the recycled coarse aggregate, takes the resource recycling of wastes into consideration, and has higher environmental benefit and social benefit.
The above embodiments are preferred embodiments of the present invention, but the present invention is not limited to the above embodiments, and any other changes, modifications, substitutions, combinations, and simplifications which do not depart from the spirit and principle of the present invention should be construed as equivalents thereof, and all such changes, modifications, substitutions, combinations, and simplifications are intended to be included in the scope of the present invention.
Claims (2)
1. A method for preparing 3D printing concrete on site by utilizing commercial concrete is characterized by comprising the following steps:
preparing commercial concrete, wherein the commercial concrete comprises the following components in parts by weight: 80-120 parts of natural macadam, 80-150 parts of river sand, 20-50 parts of regenerated coarse aggregate, 50-100 parts of cement, 10-40 parts of active admixture, 0.5-2 parts of fiber, 0.25-2 parts of water reducer and 15-50 parts of water;
the commercial concrete meets the following conditions: 1) the natural macadam is in continuous gradation, and the particle size of the natural macadam is 5-15 mm; 2) the river sand is continuous graded medium sand or fine sand, the fineness modulus is 3.0-1.6, and the particle size is 0.15-4.75 mm; 3) the recycled coarse aggregate is derived from waste concrete, is obtained by crushing and screening, and has the particle size of 5-15 mm; 4) the cement is selected from one or more of portland cement, slag cement, volcanic ash cement and fly ash cement; 5) the active admixture is selected from one or more of silica fume, fly ash, slag powder and metakaolin; 6) the fiber is selected from one or two of polyethylene fiber, polypropylene fiber and plant fiber, and the fiber length is 5-20 mm; 7) the water reducing agent is a polycarboxylic acid type water reducing agent;
secondly, transporting the prepared commercial concrete to a construction site, testing the slump of the commercial concrete on the construction site, judging whether the slump meets the pumping requirement, and pumping the commercial concrete to a concrete secondary mixing container;
step three, preparing a special additive for 3D printing concrete, wherein the special additive comprises the following components in parts by weight: 0-2 parts of defoaming agent, 0.5-2 parts of cellulose ether, 0.1-2 parts of polyacrylamide, 0.1-3 parts of accelerating agent, 0.1-3 parts of early strength agent and 1-5 parts of attapulgite; weighing all raw materials, mixing the raw materials together, uniformly stirring the raw materials, and then adding a special additive into commercial concrete in a concrete secondary stirring container, wherein the weight ratio of the special additive to a cementing material is 1/100-5/100, and the cementing material is cement and an active admixture in the commercial concrete;
the defoaming agent is a special defoaming agent for concrete; the cellulose ether is carboxymethyl cellulose ether or lignocellulose ether; the polyacrylamide is used for concrete, and the molecular weight is between 300-1000 ten thousand; the accelerator is an alkali-free accelerator; the early strength agent is an organic or compound early strength agent for concrete; the attapulgite is nano purified attapulgite clay powder for concrete;
and step four, adjusting the stirring speed of the concrete secondary stirring container to be 20-150rpm, and stirring for 5-10 minutes to obtain the 3D printing concrete.
2. The method as claimed in claim 1, wherein the slump of the commercial concrete after the preparation and transportation to the construction site at the mixing station reaches the requirement of 120-200mm, and the commercial concrete can be pumped on site.
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| CN114804791A (en) * | 2022-05-07 | 2022-07-29 | 西安建筑科技大学 | 3D printing concrete with adjustable and controllable rheological property, preparation method and printing process |
| EP4335831A1 (en) * | 2022-09-07 | 2024-03-13 | Holcim Technology Ltd | Method of placing a flowable construction material |
| CN116396036B (en) * | 2023-05-17 | 2023-08-04 | 天津市宏达伟业科技有限公司 | 3D printing concrete capable of being constructed by wide-caliber spray heads and preparation method thereof |
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| WO2015157148A1 (en) * | 2014-04-07 | 2015-10-15 | Sabic Global Technologies B.V. | Powder bed fusing thermoplastic polymers |
| CN107619230B (en) * | 2017-09-20 | 2020-09-11 | 东南大学 | Concrete material for 3D printing |
| CN108484041A (en) * | 2018-04-10 | 2018-09-04 | 深圳市明远建筑科技有限公司 | One kind is based on 3D printing cement base inorganic cementitious material and preparation method thereof |
| CN110903065A (en) * | 2019-12-13 | 2020-03-24 | 大连大学 | Quick-setting 3D printing cement-based material |
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