CN114790103B - High-thixotropy 3D printing concrete with long opening time and preparation method thereof - Google Patents
High-thixotropy 3D printing concrete with long opening time and preparation method thereof Download PDFInfo
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- CN114790103B CN114790103B CN202210498136.4A CN202210498136A CN114790103B CN 114790103 B CN114790103 B CN 114790103B CN 202210498136 A CN202210498136 A CN 202210498136A CN 114790103 B CN114790103 B CN 114790103B
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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
- 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
- B33Y70/10—Composites of different types of material, e.g. mixtures of ceramics and polymers or mixtures of metals and biomaterials
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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
- C04B20/00—Use of materials as fillers for mortars, concrete or artificial stone according to more than one of groups C04B14/00 - C04B18/00 and characterised by shape or grain distribution; Treatment of materials according to more than one of the groups C04B14/00 - C04B18/00 specially adapted to enhance their filling properties in mortars, concrete or artificial stone; Expanding or defibrillating materials
- C04B20/02—Treatment
- C04B20/026—Comminuting, e.g. by grinding or breaking; Defibrillating fibres other than asbestos
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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
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/12—Nitrogen containing compounds organic derivatives of hydrazine
- C04B24/123—Amino-carboxylic acids
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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
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2641—Polyacrylates; Polymethacrylates
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- 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
- C04B24/00—Use of organic materials as active ingredients for mortars, concrete or artificial stone, e.g. plasticisers
- C04B24/24—Macromolecular compounds
- C04B24/26—Macromolecular compounds obtained by reactions only involving carbon-to-carbon unsaturated bonds
- C04B24/2688—Copolymers containing at least three different monomers
- C04B24/2694—Copolymers containing at least three different monomers containing polyether side chains
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- 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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- 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
- C04B2103/00—Function or property of ingredients for mortars, concrete or artificial stone
- C04B2103/44—Thickening, gelling or viscosity increasing agents
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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
- C04B2111/00—Mortars, concrete or artificial stone or mixtures to prepare them, characterised by specific function, property or use
- C04B2111/00034—Physico-chemical characteristics of the mixtures
- C04B2111/00181—Mixtures specially adapted for three-dimensional printing (3DP), stereo-lithography or prototyping
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- 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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- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02W—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO WASTEWATER TREATMENT OR WASTE MANAGEMENT
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Abstract
The invention discloses high-thixotropy 3D printing concrete with long opening time and a preparation method thereof, and the concrete comprises 300-500 parts of Portland cement, 300-750 parts of inorganic filler, 0.5-1.5 parts of fiber, 0.5-3 parts of ester-based modified polyacrylic acid thickener, 0.5-5 parts of macromolecular side chain acrylic polymer, 0.5-3 parts of diethylenetriamine pentaacetic acid, 50-100 parts of fulvic acid modified tailing slag powder and 90-150 parts of tap water. The ground and fulvic acid etched modified tailing slag powder has high reaction activity, large specific surface area and low content of harmful metal ions, and can enhance the strength of concrete and endow the concrete with good thixotropy and water retention. Acrylic polymer with larger side chain molecules, diethylenetriamine pentaacetic acid and ester-based modified polyacrylic acid thickening agent have good compatibility. The prepared concrete has high thixotropy and long opening time, is beneficial to continuous construction of large-scale 3D printing engineering, and utilizes tailing slag as resources, thereby being more environment-friendly.
Description
Technical Field
The invention belongs to the technical field of building materials, and particularly relates to high-thixotropy 3D printing concrete with long opening time and a preparation method thereof.
Background
As a novel additive manufacturing technology, the concrete 3D printing construction technology can automatically manufacture three-dimensional entities layer by layer along a preset digital path, greatly improves the construction efficiency and reduces the labor cost. In addition, the technology does not need template support when stacking concrete members, thereby simplifying construction procedures, reducing construction cost and greatly improving the degree of freedom of construction. The high degree of automation and intelligence, the ability to easily prepare complex building configurations, and the superior environmental friendliness make it extremely promising, and has become one of the hot spots of current research.
For 3D printed concrete, the most important performance is thixotropy, namely, the 3D printed concrete can be continuously and smoothly extruded out under the shearing force action of a screw at a nozzle, and after extrusion, the 3D printed concrete can resist the gravity of upper concrete without excessive deformation and expansion under the standing condition without external force action. In addition, due to early hydration of cement particles, 3D printing concrete gradually becomes dry and hard and cannot be printed with time, and the duration from the time when the 3D printing concrete is mixed to the time when the 3D printing concrete cannot be continuously and smoothly extruded from a printing nozzle is generally defined as the opening time of the 3D printing concrete. In mass production applications, long open times are critical to ensure the quality of the printed components and to avoid waste of concrete material.
The mineral reserves in China are rich, a large amount of tailing slag is discharged after useful minerals are separated, the comprehensive utilization rate of the tailing slag in China is only 18.9 percent at present, and the stacking of the tailing slag occupies a large amount of land resources and causes serious environmental pollution. The nickel-iron slag, the manganese tailing slag and the lead-zinc tailing slag are mostly complex in components, low in activity and large in metal ion content, and the reason is important for limiting resource utilization. The existing documents and patents mainly utilize nickel-iron slag, manganese tailing slag, lead-zinc tailing and other mineral admixtures to prepare the alkali-activated cementing material, but the prepared alkali-activated cementing material has the problems of unstable performance, larger shrinkage and the like, cannot be produced and applied in a large scale, and simultaneously needs to be matched with a plurality of raw materials for use, and has complex components and process. Chinese patent CN201610943714.5 provides a 3D printing building material, which is prepared from water granulated slag ultrafine powder, fly ash fine powder, cement ultrafine powder, tailing micropowder, tailing slag, steel slag, a water reducing agent, glass fiber, an additive solution and water, and can be printed smoothly, but the initial setting time of the material is only 20-30 min, the final setting time is only 39-55 min, the opening time is too short, and the material is difficult to adapt to mass long-time printing in practical engineering.
Disclosure of Invention
The invention aims to: the invention aims to provide high-thixotropy 3D printing concrete with long opening time and a preparation method thereof, and mainly aims to promote the application of the 3D printing concrete in actual large-scale engineering and ensure the stability and the safety of the quality of a large-scale printing component.
The technical scheme is as follows: the high-thixotropy 3D printing concrete with long opening time comprises the following components in parts by weight:
300 to 500 portions of Portland cement,
300 to 750 portions of inorganic filler component,
0.5 to 1.5 portions of fiber component,
0.5 to 3 portions of ester-based modified polyacrylic acid thickening agent,
0.5 to 5 portions of macromolecular side chain acrylic polymer,
0.5 to 3 portions of diethylenetriamine pentaacetic acid,
50 to 100 portions of fulvic acid modified tailing slag powder,
90-150 parts of water.
Further, the portland cement component comprises ordinary portland cement, portland slag cement, pozzolanic portland cement, portland fly ash cement, or composite portland cement having a strength grade of 52.5 or more according to the standard for portland cement of GB 175-2007.
Further, the inorganic filler component comprises any one of artificial sand, natural sand and quartz sand which is compounded with ground brick powder, the particle size range of the inorganic filler is 0.3-2.36 mm, the fineness modulus is 1.6-2.4, and the mud content and the harmful substance limit amount are less than the specified amount in the GB/T14684-2011 building sand standard.
Further, the fiber component includes polypropylene fibers, polyvinyl alcohol fibers, steel fibers or basalt fibers; the diameter of the fiber is 3-9 mm.
Further, the ester-based modified polyacrylic acid thickener is prepared in a specific manner as follows: adding acrylic acid and ethyl acetate containing half of the total amount of small monomers into a four-neck flask provided with a stirrer, a thermometer and a reflux condensing device, heating to 55 +/-2 ℃, dropwise adding a proper amount of 30% volume concentration hydrogen peroxide solution, and stirring at a certain speed for 10-30 min. Then, the chain transfer agent and the initiator are uniformly mixed at a certain stirring rate to prepare a solution A, and the other half of small monomers are prepared into a solution B. And then dripping the solution A into a four-mouth beaker at a constant speed for 60-90 min, dripping the solution B into the four-mouth beaker at a constant speed for 45-90 min, continuously keeping the temperature at 55 +/-2 ℃ after finishing dripping, and continuously stirring for 60-120 min. Finally, vacuum drying is carried out for 24-48 h at the temperature of 40 +/-5 ℃, and white powder ester-based modified polyacrylic acid thickening agent is obtained.
Further, the specific preparation method of the macromolecular side chain acrylic polymer is as follows: adding a certain amount of deionized water and isobutylene polyoxyethylene ether or isopentenyl polyoxyethylene ether into a four-neck flask provided with a stirrer, a thermometer and a reflux condensing device, stirring and heating to 55 +/-2 ℃, then dropwise adding a solution A consisting of a certain amount of acrylic acid, hydroxyethyl acrylate and 30% volume concentration hydrogen peroxide and a solution B consisting of deionized water and a reducing agent at a constant speed, wherein the dropwise adding time of the two solutions is respectively 40-60 min and 60-90 min, keeping 30-40 ℃ for curing for 30-60 min after dropwise adding, adding a certain amount of 10% sodium hydroxide solution, adjusting the pH to 6-8, and obtaining a liquid which is the macromolecular side chain acrylic polymer.
Further, the specific preparation method of the fulvic acid modified tailing slag powder comprises the following steps: putting the tailing slag particles and a high-molecular polycarboxylic acid-alcohol amine type high-efficiency grinding aid with the weight of 0.03 percent of the tailing slag particles into a ball mill together for crushing and grinding treatment, etching for 6-12 hours by using a 0.1mol/L fulvic acid solution after 1-3 hours, and drying to obtain the high-performance slag grinding aid.
Further, the tailing slag particles are any one of nickel-iron slag, manganese tailing slag and lead-zinc tailing slag or a mixture of the nickel-iron slag, the manganese tailing slag and the lead-zinc tailing slag in any proportion.
The invention also discloses a preparation method of the high-thixotropy 3D printing concrete with long opening time, which comprises the following steps:
step 1, weighing a portland cement component and an inorganic filler component according to a proportion, and stirring for 0.5-2.0 min to obtain a mixed dry material;
step 2, adding the macromolecular side chain acrylic polymer, diethylenetriamine pentaacetic acid and tap water into the mixed dry material, and stirring for 1-2 min;
step 3, adding the fiber component into the mixture, and stirring for 2-3 min;
and 4, adding the ester-based modified polyacrylic acid thickener and the fulvic acid modified tailing slag powder into the mixture, and stirring for 2 n-3 min to obtain the product.
Has the beneficial effects that: compared with the prior art, the invention has the following remarkable advantages:
(1) Fulvic acid is a macromolecular mixture widely existing in surface environments of various places in the nature, contains a large number of active groups, has the characteristics of acidity, hydrophilicity, interfacial activity, ion exchange capacity, adsorption capacity, complexing capacity and the like, and can be extracted from substances such as municipal sludge, leaves and the like. The modified tailing slag powder subjected to efficient grinding and fulvic acid etching has a large specific surface area, and meanwhile, the volcanic ash activity of the tailing slag can be further enhanced by improving the interfacial activity, the ion exchange capacity and the hydrophilicity of groups such as ketone carbonyl, carboxyl and the like adsorbed on the surface of the tailing slag powder, so that the microstructure of concrete is more compact, and the strength is improved. The generation of flocculation structures among particles can be promoted due to the large surface activity and adsorption capacity, the adsorption of water molecules is effectively enhanced by hydrophilic groups adsorbed on the surface of the tailing slag powder, the water retention of concrete is improved, and the opening time of the concrete is prolonged. And because the flocculation structure among the early particles is weakly connected, the flocculation structure is easily destroyed under the action of external force, so that the concrete has better thixotropy. In addition, the tailing slag contains a plurality of heavy metal ions, the tailing slag is used for preparing the building material in a large amount, once the heavy metal ions are dissolved out, serious pollution and harm can be caused to the environment and human bodies, the fulvic acid has good adsorption effect on the heavy metal ions such as copper, cadmium, lead, zinc and the like, the content of the heavy metal ions in the modified tailing slag can be effectively reduced, and the modified tailing slag is more environment-friendly. The invention provides a novel tailing slag resource utilization mode, which is beneficial to environmental protection and sustainable development, the operation is simple, the thixotropy and the water retention of 3D printed concrete are improved by the prepared modified tailing slag powder, the concrete is favorably and uniformly extruded under the action of the shearing force of a screw, the building performance is good when no external force is applied after the concrete is extruded, and the printing open time is prolonged.
(2) The macromolecular side chain acrylic polymer is formed by polymerizing acrylic acid, isobutylene polyoxyethylene ether or isopentenyl polyoxyethylene ether and the like, and a larger molecular side chain generates larger electrostatic repulsion and steric hindrance, so that the concrete obtains higher fluidity and lower yield stress under the condition of less water consumption, and the concrete is easy to extrude while having higher mechanical strength. In addition, ester groups and amide groups contained in the macromolecular side chain acrylic polymer can be slowly hydrolyzed in an alkaline environment to release hydrophilic carboxyl groups, so that the setting time and the opening time of concrete are prolonged. The nitrogen atom of the coordination atom in the diethylenetriamine pentaacetic acid has stronger complexing effect with metal ions, and can absorb free calcium ions in cement paste to occupy the crystal site of normal growth of calcium hydroxide crystals, so that the formation of crystal nuclei is prevented, and the hydration rate of cement is controlled. The two components can ensure the retarding effect under the combined action, and the problems that the single retarding component has poor compatibility with cement, other additives or mineral admixtures and loses the retarding effect are solved.
(3) The ether bond in the thickening agent and the amido group, the carboxyl group and other groups have a competitive adsorption relationship, and the water reducing effect of the macromolecular side chain acrylic polymer can be disabled. Thus, the acrylic thickener is modified with ester groups to reduce its interference with the initial adsorption of the macromolecular pendant acrylic polymer. As the cement hydration is carried out, the alkalinity in the system is increased, ester groups in the thickening agent are decomposed, the effects of macromolecular crosslinking, adsorption and the like are initiated, and the plastic viscosity and the thixotropy of the concrete are further improved. Therefore, under the combined action of the ester-based modified polyacrylic acid thickener, the macromolecular side chain acrylic acid polymer and the diethylenetriamine pentaacetic acid, the ester-based modified polyacrylic acid thickener has better constructability after the concrete is extruded and deposited under the condition of not influencing the smooth extrusion of the concrete, and simultaneously prolongs the opening time of the concrete.
Detailed Description
The technical solution of the present invention is further explained below.
Example 1 a high thixotropic 3D printed concrete with a long open time consists of the following components in parts by mass:
the portland cement component is PII52.5 portland cement 300 parts by weight.
The inorganic filler component is prepared by compounding natural sand and ground brick powder, the particle size of the obtained filler is 0.3-2.36 mm, the fineness modulus is 1.6, and the mass portion is 300.
The fiber is polypropylene fiber with the diameter of 6mm, and the mass portion is 0.5 portion.
0.5 part of ester-based modified polyacrylic acid thickening agent.
2 parts of macromolecular side chain acrylic polymer.
1 part of diethylenetriamine pentaacetic acid by mass
The fulvic acid modified tailing slag powder comprises 50 parts by weight.
The mass portion of the tap water is 90 portions.
Example 2 a high thixotropic 3D printed concrete with a long open time was composed of the following parts by mass:
the portland cement component is PII52.5 portland cement 300 parts by weight.
The inorganic filler component is prepared by compounding natural sand and ground brick powder, the particle size of the obtained filler is 0.3-2.36 mm, the fineness modulus is 2, and the mass portion is 450.
The fiber is polypropylene fiber with the diameter of 6mm, and the mass portion is 1 portion.
1.5 parts of ester-based modified polyacrylic acid thickening agent.
3 parts of macromolecular side chain acrylic polymer.
2 portions of diethylenetriamine pentaacetic acid
The fulvic acid modified tailing slag powder comprises 75 parts by weight.
The mass portion of tap water is 120 portions.
Example 3 a high thixotropic 3D printed concrete with a long open time consists of the following parts by mass:
the portland cement component is PII52.5 portland cement 400 parts by weight.
The inorganic filler component is prepared by compounding natural sand and ground brick powder, the particle size of the obtained filler is 0.3-2.36 mm, the fineness modulus is 2.4, and the mass portion is 750 parts.
The fiber is polypropylene fiber with the diameter of 6mm, and the mass portion is 1.5 portions.
The ester-based modified polyacrylic acid thickening agent comprises 3 parts by weight.
5 parts of macromolecular side chain acrylic polymer.
3 portions of diethylenetriamine pentaacetic acid
The fulvic acid modified tailing slag powder comprises 100 parts by weight.
The mass portion of the tap water is 150 portions.
Example 4 a high thixotropic 3D printed concrete with a long open time consists of the following parts by mass:
the portland cement component adopts PII52.5 portland cement with the mass portion of 350 parts.
The inorganic filler component is prepared by compounding natural sand and ground brick powder, the particle size of the obtained filler is 0.3-2.36 mm, the fineness modulus is 2.2, and the mass portion is 750 parts.
The fiber is polypropylene fiber with the diameter of 6mm, and the mass portion is 1.2 portions.
0.5 part of ester-based modified polyacrylic acid thickening agent.
The mass portion of the macromolecular side chain acrylic polymer is 2 portions.
1.5 parts of diethylenetriamine pentaacetic acid
The fulvic acid modified tailing slag powder comprises 90 parts by mass.
The mass portion of the tap water is 150 portions.
Example 5 a high thixotropic 3D printed concrete with a long open time consists of the following parts by mass:
the portland cement component is PII52.5 portland cement 380 parts by mass.
The inorganic filler component is prepared by compounding natural sand and ground brick powder, the particle size of the obtained filler is 0.3-2.36 mm, the fineness modulus is 1.8, and the mass portion is 600.
The fiber is polypropylene fiber with the diameter of 6mm, and the mass portion is 1 portion.
1.5 parts of ester-based modified polyacrylic acid thickening agent.
4 parts of macromolecular side chain acrylic polymer.
1 part of diethylenetriamine pentaacetic acid by mass
The fulvic acid modified tailing slag powder comprises 100 parts by weight.
The mass portion of the tap water is 100 portions.
Example 6 a high thixotropic 3D printed concrete with a long open time consists of the following parts by mass:
the portland cement component is PII52.5 portland cement 260 parts by mass.
The inorganic filler component is prepared by compounding natural sand and ground brick powder, the particle size of the obtained filler is 0.3-2.36 mm, the fineness modulus is 2, and the mass portion is 600 portions.
The fiber is polypropylene fiber with the diameter of 6mm, and the mass portion is 0.7 portion.
0.5 part of ester-based modified polyacrylic acid thickening agent.
3 parts of macromolecular side chain acrylic polymer.
0.5 portion of diethylenetriamine pentaacetic acid
The fulvic acid modified tailing slag powder comprises 85 parts by mass.
The mass portion of the tap water is 80 portions.
The method for producing the fulvic acid-modified tailing slag powder described in example 1-2 was: and (2) putting the tailing slag particles and a high-molecular polycarboxylic acid-alcohol amine type efficient grinding aid with the weight of 0.03 percent into a ball mill together for crushing and grinding treatment, after 1 hour, etching for 6 hours by using a 0.1mol/L fulvic acid solution, and drying to obtain the high-performance slag grinding aid. The tailing slag particles are nickel-iron slag and lead-zinc tailing slag according to the weight ratio of 1:1 is obtained by compounding.
The method for producing the fulvic acid-modified tailing slag powder described in example 3-4 was: and (2) putting the tailing slag particles and a high-molecular polycarboxylic acid-alcohol amine type efficient grinding aid with the weight of 0.03 percent into a ball mill together for crushing and grinding treatment, after 1 hour, etching for 6 hours by using a 0.1mol/L fulvic acid solution, and drying to obtain the high-performance slag grinding aid. The tailing slag particles are nickel-iron slag and manganese tailing slag according to the weight ratio of 1:1 is obtained by compounding.
The method for producing the fulvic acid-modified tailing slag powder described in example 5-6 was: and (2) putting the tailing slag particles and a high-molecular polycarboxylic acid-alcohol amine type high-efficiency grinding aid accounting for 0.03 percent of the weight of the tailing slag particles into a ball mill together for crushing and grinding, after 1 hour, etching for 6 hours by using a 0.1mol/L fulvic acid solution, and drying to obtain the high-efficiency grinding aid. The tailing slag particles are lead-zinc tailing slag and manganese tailing slag according to the weight ratio of 1:1 is obtained by compounding.
The long open-time, highly thixotropic, 3D-printed concrete described in examples 1-6 was prepared as follows:
s1, weighing a portland cement component and an inorganic filler component according to a proportion, and stirring for 1.0min to obtain a mixed dry material;
s2, adding the macromolecular side chain acrylic polymer, diethylenetriamine pentaacetic acid and tap water into the mixed dry material, and stirring for 2.0min;
s3, adding the fiber component into the mixture, and stirring for 2.0 mins;
and S4, adding the ester-based modified polyacrylic acid thickener and the fulvic acid modified tailing slag powder into the mixture, and stirring for 3.0min.
Obtaining static yield stress, plastic viscosity and thixotropy value of concrete by a rheological property test (a Brookfield rheometer is adopted, a test rotor is a paddle type rotor, the inner diameter and the outer diameter are 20mm and 40mm respectively, the test conditions are that the temperature is 25 +/-2) DEG C, the relative humidity is 70 +/-3%, the adopted rheological system is that the shear rate in the first 30s is linearly increased from 0 to 80s < -1 >, the shear rate in the last 30s is linearly reduced from 80s < -1 > to 0, the highest point of a hysteretic curve is taken as the static yield stress, the plastic viscosity is fitted through a Bingham model, and the thixotropy is calculated according to the hysteretic ring area), testing the final setting time of the concrete by a setting time test (referring to a Vicat instrument final setting test method), and determining the opening time of the concrete by extruding from a printing nozzle after the concrete is mixed to be incapable of being uniform and smooth. According to the sample size and the test system of the GB/T17671-2020 cement mortar strength test method, the compressive strength of the samples 1-6 and the control group which are cured for 28 days under the conditions of 20 +/-5 ℃ and the relative humidity of more than or equal to 95 percent is tested after the printed concrete is cut. The test results obtained are shown in table 1. The control group adopts a commercial 3D printing concrete formula and is prepared from the following substances in parts by weight:
and (3) cementing materials: a superplasticizer: thickening agent: thixotropic agent: water: sand: fiber =100:2:0.5:5:30:150: 2.
The cementing material adopts Portland cement of PII 52.5.
The superplasticizer is an early-strength polycarboxylic acid high-performance water reducing agent.
The thickener is hydroxypropyl methylcellulose with the viscosity of 75000.
The thixotropic agent is silica fume.
The sand is natural sand with the grain diameter of 0.3-2.36 mm, and the fineness modulus is 1.8.
The fiber is polyethylene fiber with diameter of 6 mm.
TABLE 1 concrete Performance test results
The results in table 1 show that examples 1-6 have lower yield stress and higher thixotropy than commercial 3D printed concrete while having comparable or lower initial plastic viscosity, indicating that examples 1-6 have better constructability after deposition while being easier to extrude. Also, the final set time and open time of examples 1-6 were greater than the control, showing better printability retention, more suitable for the preparation of large 3D printed components. In addition, the modified tailing slag powder can perform a pozzolan reaction with calcium hydroxide generated by cement hydration, fill and compact a concrete micro-pore structure, and enhance the compressive strength of the concrete.
Claims (8)
1. The high-thixotropy 3D printing concrete with long opening time is characterized by comprising the following components in parts by weight:
300 to 500 portions of Portland cement,
300 to 750 portions of inorganic filler component,
0.5 to 1.5 portions of fiber component,
0.5 to 3 portions of ester-based modified polyacrylic acid thickening agent,
0.5 to 5 portions of macromolecular side chain acrylic polymer,
0.5 to 3 portions of diethylenetriamine pentaacetic acid,
50 to 100 portions of fulvic acid modified tailing slag powder,
90-150 parts of water;
the ester group modified polyacrylic acid thickening agent is prepared in the following specific preparation mode: adding acrylic acid and ethyl acetate containing half of the total amount of small monomers into a four-mouth flask provided with a stirrer, a thermometer and a reflux condensing device, heating to 55 +/-2 ℃, dropwise adding a proper amount of 30 volume percent hydrogen peroxide solution, stirring at a certain speed for 10-30 min, uniformly mixing a chain transfer agent and an initiator at a certain stirring speed to prepare a solution A, preparing the other half of small monomers into a solution B, dropwise adding the solution A into the four-mouth flask at a constant speed for 60-90 min, dropwise adding the solution B at a constant speed for 45-90 min, continuously keeping the temperature at 55 +/-2 ℃ after dropwise adding, continuously stirring for 60-120 min, and finally vacuum drying at 40 +/-5 ℃ for 24-48 h to obtain the white powder ester-based modified polyacrylic acid thickening agent.
2. The long open time, high thixotropy, 3D printed concrete according to claim 1, wherein said portland cement component comprises ordinary portland cement, slag portland cement, pozzolanic portland cement, fly ash portland cement, or composite portland cement of the GB175-2007 universal portland cement standard with an intensity grade of 52.5 or greater.
3. The long-open-time high thixotropy 3D printing concrete according to claim 1, characterized in that said inorganic filler component comprises any one of artificial sand, natural sand and quartz sand compounded with ground brick powder, the particle size range of the inorganic filler is 0.3-2.36 mm, the fineness modulus is 1.6-2.4, and the mud content and the harmful substance limit amount are less than the specified amount in GB/T14684-2011 building sand standard.
4. The long open time, high thixotropic, 3D printed concrete according to claim 1, wherein the fiber component comprises polypropylene fibers, polyvinyl alcohol fibers, steel fibers, or basalt fibers; the diameter of the fiber is 3-9 mm.
5. The long-open-time high thixotropic 3D printed concrete according to claim 1, wherein the macromolecular side chain acrylic polymer is specifically prepared by: adding a certain amount of deionized water and isobutylene polyoxyethylene ether or isopentenyl polyoxyethylene ether into a four-neck flask provided with a stirrer, a thermometer and a reflux condenser, stirring and heating to 55 +/-2 ℃, then dropwise adding a solution A consisting of a certain amount of acrylic acid, hydroxyethyl acrylate and 30 volume percent hydrogen peroxide and a solution B consisting of deionized water and a reducing agent at a constant speed, wherein the dropwise adding time of the two solutions is 40-60 min and 60-90 min respectively, keeping the temperature of 30-40 ℃ for curing for 30-60 min after the dropwise adding is finished, adding a certain amount of 10 percent sodium hydroxide solution, and adjusting the pH to 6-8 to obtain the liquid, namely the macromolecular side chain acrylic polymer.
6. The long-open-time high thixotropic 3D printing concrete according to claim 1, wherein the fulvic acid modified tailing slag powder is prepared by a specific method comprising: and (2) putting the tailing slag particles and a high-molecular polycarboxylic acid-alcohol amine type high-efficiency grinding aid accounting for 0.03 percent of the weight of the tailing slag particles into a ball mill together for crushing and grinding, etching for 6-12 hours by using a 0.1mol/L fulvic acid solution after the tailing slag particles and the high-molecular polycarboxylic acid-alcohol amine type high-efficiency grinding aid last for 1-3 hours, and drying to obtain the high-performance slag grinding aid.
7. The long-open-time high thixotropic 3D printed concrete according to claim 6, wherein the tailing slag particles are any one or a mixture of two of nickel-iron slag, manganese tailing slag and lead-zinc tailing slag in any proportion.
8. A method for preparing a long-open-time high thixotropic 3D printed concrete according to claim 1, comprising the steps of:
step 1, weighing a portland cement component and an inorganic filler component according to a proportion, and stirring for 0.5-2.0 min to obtain a mixed dry material;
step 2, adding the macromolecular side chain acrylic polymer, diethylenetriamine pentaacetic acid and tap water into the mixed dry material, and stirring for 1-2 min;
step 3, adding the fiber component into the mixture, and stirring for 2-3 min;
and 4, adding the ester-based modified polyacrylic acid thickener and the fulvic acid modified tailing slag powder into the mixture, and stirring for 2-3 min to obtain the product.
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