JP2022542640A - 3D printed concrete of coastal deformed structure, fabrication process and application - Google Patents

Abstract

The invention specifically relates to 3D printing concrete, fabrication processes and applications of coastal profile structures. 3D printed concrete of conventional coastal deformed structure, when the ordinary marine anticorrosion technology is applied to the 3D printed coastal deformed structure, the anticorrosion effect is not favorable, and the bonding and thixotropic property of the interlayer interface of ordinary 3D printing materials has the disadvantage of being low. The present invention provides coastal deformed structure 3D printed concrete, raw materials are composite cement, recycled sand, fly ash, polyvinyl alcohol, graphene oxide, steel fiber, organic fiber, water reducing agent, coagulation modifier, mineral admixture and Contains water. The 3D-printed concrete has excellent cohesive water retention and connectivity of adjacent lamella interfaces, and the combination of GO and PVA electrolyte to form micro-capacitors can reduce corrosive battery in concrete lamellae. It avoids the formation of , has excellent marine durability, and has excellent future application potential when applied to coastal deformed structure construction. [Selection drawing] Fig. 2

Description

The present invention belongs to the technical field of 3D printing of coastal structures, and specifically relates to 3D printing concrete of coastal deformed structures, the working process of said 3D printed concrete of coastal deformed structures and its application in the production of coastal deformed structures.

The information in this background section disclosed is for the sole purpose of enhancing the understanding of the general background of the invention, and is not an admission or any form of disclosure that this information constitutes prior art known to those of ordinary skill in the art. It is not necessarily considered a proposal.

At present, in the industrial upgrade situation of digitalization, industrialization and intelligentization of architecture, different specifications of seismic walls for structural prefabricated buildings, laminated floor slabs, laminated beams, laminated columns, prefabricated stairs, integrated toilets, garbage chutes, etc. There is a need for rapid production of various concrete prefabricated members in the field. In addition, the recycling and utilization of construction waste effectively relieves the pressure of urban ecological protection and energy conservation and emission reduction. In recent years, the digitized construction method based on robotic 3D printing, which has been developing rapidly, can precisely control the construction accuracy of various deformed concrete members and manufacture various curved members with beautiful shapes. , no need to pre-manufacture molds, no need to process a large amount of material in the manufacturing process, no need to go through a complicated forging process, the final production is structural optimization, material saving and energy saving can be saved, effectively realizing the industrialization, intelligence and resource saving of assembly building, and the future application potential is very wide.

At the same time, reinforced concrete structures are widely used in the engineering field of coastal structures such as bridges and tunnels, wind energy nuclear power plants, oil drilling platforms, ports and wharves. Similarly, based on 3D printing technology, coastal profiled structures such as manhole covers, rainwater grids, underground pipes, egg-shaped cisterns, subway pipes, honeycomb beams, laminated beams/slabs can be rapidly manufactured, attracting wide attention. .

3D printed concrete is generally not added with reinforcing steel skeleton, but is doped with high-strength, high-modulus chopped steel fibers to meet the requirements of 3D-printed concrete with high early strength and excellent toughness deformation. cannot be ignored. However, the success of 3D printing of complex concrete members depends on the properties of the corresponding concrete slurries, such as fast setting speed, high water retention cohesiveness, high plasticity, excellent interlayer bonding and thixotropy. Depends on features. In addition, coastal structural concrete is a porous, multiphase, non-homogeneous material, and seawater and oxygen gas reach the surface of the steel fibers along the pores in the concrete, creating corrosive free electrons. . These electrons are transported through the steel fibers to the cathode area, and the negative ions in the solution are transported through the pore solution to the anode area, easily forming a large amount of corrosive micro-batteries, and even failing faster. put away.

However, when developing 3D printed concrete materials for coastal assembly structures, the inventor found the following problems.

(1) Coastal deformed structures have complex curved surfaces and are mostly thin-walled structures, whereas 3D-printed concrete is printed layer-by-layer, and has enough thickness to protect randomly dispersed steel fibers from marine corrosion. Having the thickness of a concrete protective layer is difficult. Also, conventional marine anti-corrosion techniques such as coating anti-corrosion layers on the surface and adding cathodic protection cannot be used or are less effective for coastal profile structures where printed interfacial layers continue to be present.

(2) It has good rheology, water retention cohesion, mechanical toughness and volume stability, as well as sufficient inter-layer interface bonding and thixotropy when using ordinary 3D printing concrete materials to print coastal deformed structures. It is difficult to have.

(3) When using ordinary 3D printing concrete materials to print coastal deformed structures, construction or industrial solid wastes can be recycled at the same time, effectively exerting the pressure of urban ecological protection and energy conservation and emission reduction. It is difficult to reduce it effectively and achieve the environmental protection effect.

In view of the problems described in the above background art, the present invention aims to provide an optimized coastal profiled structure 3D printed concrete, the coastal profiled structure obtained by printing has a good marine anticorrosion effect and bond and thixotropy at the interface between layers.

Based on the above technical effects, the present invention provides the following technical solutions.

In a first aspect of the present invention, there is provided a coastal deformed structure 3D-printed concrete, said coastal deformed structure 3D-printed concrete comprising: 1 part by weight of composite cement, 1-2 parts by weight of recycled sand, 0.5 parts by weight of fly ash (FA). 05-0.2 parts by weight, polyvinyl alcohol (PVA) 0.005-0.05 parts by weight, graphene oxide (GO) 0.0002-0.002 parts by weight, steel fibers 0.01-0.05 parts by weight, 0.005-0.02 parts by weight of organic fibers, 0.005-0.01 parts by weight of water reducing agent, 0.005-0.01 parts by weight of coagulation modifier, 0-0.05 parts by weight of mineral mixture and 0 parts by weight of water .3-0.5 parts by weight, said PVA further comprising an oxidizing agent and a catalyst.

The coastal deformed structure 3D printing concrete manufactured with the above raw materials and mixing ratio can be printed to print coastal deformed concrete structures with different specifications according to the needs of conventional mechanical arm and structural model parameter printing. The printed coastal profile structures also have excellent marine durability.

The present invention can obtain the raw materials and mixing ratio of the above-mentioned 3D printing concrete through constant efforts, including many hydroxyl groups, epoxy groups, GOs containing functional groups such as carboxyl groups, and many hydroxyl groups. PVA allows the 3D-printed concrete to have excellent cohesive water retention, as well as excellent interfacial bonding between adjacent 3D-printed concrete thin layers. By including GO-PVAH@FA, the 3D printed concrete slurry has a shear thinning effect, achieving excellent thixotropy and plasticity of the slurry. In addition, GO containing hydrophilic groups can be stably combined with PVA electrolyte to form a large amount of GO-PVAH microcapacitors, and these microcapacitors can be transferred to GO-PVAH in 3D printed concrete thin layers through FA media. Evenly distributed in the microcapacitor, the pore solution electrolyte in the 3D printed concrete thin layer is stored in large quantities, and the ions that migrate with seawater as the medium are captured to avoid the formation of corrosive batteries in the 3D printed concrete thin layer steel fiber. , can effectively prevent the electrochemical corrosion of steel fibers, and further greatly improve the resistance of the entire coastal profile structure to chloride ion penetration and seawater corrosion.

Based on the above effects, in the second aspect of the present invention, the 3D-printed concrete of coastal deformed structure includes printing and molding the concrete dry blend material by 3D printing technology using the 3D-printed concrete raw material according to the first aspect. is provided.

In a third aspect of the invention there is provided the application of the 3D printed concrete of coastal profile structures according to the first aspect in the manufacture of coastal profile structures.

The beneficial effects of one or more of the above technical solutions are as follows.

(1) By adopting the 3D printing concrete and processing process of the coastal deformed structure of the present invention, the coastal deformed structure can be manufactured at a high speed and the marine durability can be effectively guaranteed. The present invention innovatively coats the stably dispersed GO-PVAH off the surface of the FA media to achieve long-term and uniform distribution in the subsequent nano-recycled concrete system, resulting in GO-PVAH in the recycled concrete. directly toping can effectively solve the problem of greatly reducing the fluidity of recycled concrete, resulting in the corresponding nano-recycled concrete slurry with excellent consistency and thixotropy. In addition, the GO containing hydrophilic groups is combined with the PVA prepolymer and uniformly dispersed in the recycled concrete, effectively improving the anti-isolation properties and the rheology over time of the nano-recycled concrete. Second, the internal curing of recycled aggregate and the ball lubrication effect of FA contribute to the water retention function of the corresponding recycled concrete. Third, the coagulation-modifying effects such as coagulation modifiers and the fast-setting characteristics of the composite cement further ensure the printability of the nano-recycled concrete and the buildability of each layer.

The realization mechanism of the mechanical toughness and durability of the 3D printed concrete hardened body is as follows. First, the GO surface contains many hydrophilic groups such as hydroxy, epoxy and carboxyl groups, which facilitates the compatibility of GO with the cement mortar system, and GO also has nanocrystal nuclei and templates. The effect can be sufficiently exhibited, and the micromorphology of the corresponding hardened recycled concrete can be improved. Second, GO-PVAH hydrogels and recycled aggregates can function well as internal nutrients during molding of nano-recycled concrete, after which the slow release of water leads to rapid hydration of cement. It can effectively offset the thermal shrinkage stress generated when it is used, and achieve volume stability. Third, toughness enhancement by doped chopped steel fibers and bridging effect by organic fibers further guarantee the mechanical toughness, crack resistance and oozing resistance of nano-recycled concrete.

(2) The 3D printed concrete of the coastal deformed structure of the present invention is firstly made by GO containing functional groups such as many hydroxyl groups, epoxy groups and carboxyl groups, and PVA containing many hydroxyl groups. can have excellent cohesive water retention while adjacent 3D printed concrete laminae have excellent interfacial bonding. Second, GO-PVAH@FA enables the 3D-printed concrete slurry to have a shear-thinning effect, achieving excellent thixotropy and plasticity of the slurry. Third, GO containing hydrophilic groups can be stably combined with PVA electrolyte to form a large amount of GO-PVAH microcapacitors, and these microcapacitors can be transferred in thin layers of 3D-printed concrete through the FA medium. Uniformly dispersed in GO-PVAH microcapacitor, pore solution electrolyte in 3D printed concrete thin layer is stored in bulk, ions migrated with seawater as medium, and formation of corrosive battery in 3D printed concrete thin layer steel fiber and can effectively prevent the electrochemical corrosion of steel fibers, further greatly improving the resistance of the entire coastal profile structure to chloride ion penetration and seawater corrosion.

In the nano-recycled concrete of the present invention, GO-PVAH is synthesized on the FA surface, and the aqueous medium of the external additive effectively delays the time of adding GO-PVAH@FA to the nano-recycled concrete, and the composite cement and the alkali The bottleneck problem of GO being deoxygenated in a strongly alkaline environment is innovatively avoided by using it in combination with an admixture such as FA that reduces the degree of GO. GO-PVAH coated outside the FA media surface, self-curing of recycled aggregate and ball lubrication effect of FA realize the thixotropy, chronological rheology and plasticity function of nano-recycled concrete slurry. Using the GO nanotemplate, the bridging effect of organic fibers, and the fast-hardening and early-strength effects of composite cement, comprehensively realize the continuous early-strength function, crack-resistant function, and bleed-resistant function of nano-recycled concrete. The effect of stabilizing the interfacial volume of nano-recycled concrete is realized by the internal curing of GO-PVAH and recycled aggregate, the micro-expansion of composite cement, and the effect of reducing FA. Exerting the energy storage effect of GO-PVAH microcapacitors, avoiding the formation of corrosive micro-batteries of steel fibers in 3D printed coastal structures, realizing the corrosion autoimmune effect of rebars, and printing 3D printed concrete of coastal deformed structures・Innovative realization of buildability, early strength effect, crack resistance/bleeding resistance effect and corrosion autoimmunity effect of hardened body, and expansion of recycling and utilization of solid waste.

The drawings of the specification, which form part of the invention, are used to provide a further understanding of the invention. The exemplary embodiments and descriptions of the invention are used to describe the invention and do not constitute undue limitations of the invention.

1 is a schematic diagram of the GO-PVA polymerization intercalate and GO-PVAH@FA coating process described in Example 3. FIG.

1-FA particles, 2-GO-PVA hydrogel layer, 21-GO sheet layer, 22-PVA polymer, 23-hydrogel. For those skilled in the art to understand well, the GO-PVA intercalate structure schematically shows the intercalate structure formed by the GO sheet layer and the PVA chain type polymer, and the SEM micromorphology of FA is FA spherical Figure 2 schematically shows a hollow structure and size specifications;

3 is a flow chart of 3D printing concrete and fabrication process of coastal profiled structures described in Example 3;

It should be noted that all of the following detailed descriptions are exemplary and are intended to provide further explanation of the invention. Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

Note, however, that the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of example embodiments in accordance with the present invention. As used herein, the singular is intended to include the plural unless the context clearly dictates otherwise. Further, when the terms "include" and/or "comprise" are used herein, they indicate the presence of functions, steps, operations, devices, components, and/or combinations thereof.

Against the above drawbacks of the prior art, the present invention provides its application in 3D printing concrete, fabrication process and high speed manufacturing of coastal profiled structures. GO-PVAH is synthesized on the FA surface, and the aqueous medium of the external additive effectively delays the time of adding GO-PVAH@FA to the nano-recycled concrete, resulting in low alkalinity composite cement and alkalinity-reducing FA. By using it in combination with a mixed material such as GO, it innovatively avoids the bottleneck problem that GO is deoxygenated in a strong alkaline environment. The GO-PVAH coated on the outside of the FA medium surface, the self-curing of the recycled aggregate and the ball lubrication effect of the FA realize the thixotropy, chronological rheology and water retention function of the nano-recycled concrete slurry. Using the GO nanotemplate, the bridging effect of organic fibers, and the fast-hardening and early-strength effects of composite cement, comprehensively realize the continuous early-strength function, crack-resistant function, and bleed-resistant function of nano-recycled concrete. The effect of stabilizing the interfacial volume of nano-recycled concrete is realized by the internal curing of GO-PVAH and recycled aggregate, the micro-expansion of composite cement, and the effect of reducing FA. Exerting the energy storage effect of GO-PVAH microcapacitors, avoiding the formation of corrosive micro-batteries of steel fibers in 3D printed coastal structures, realizing corrosion autoimmune effects of rebars, and nano-regeneration for 3D printing of coastal deformed structures Innovative realization of printing and building properties of concrete, early strength effect of hardened body, stable volume, crack resistance and corrosion autoimmune effect, expansion of recycling and utilization of solid waste, and finally coastal deformity It has enormous economic and environmental benefits in the field of rapid manufacturing of structures.

In a first aspect of the present invention, there is provided a coastal deformed structure 3D-printed concrete, said coastal deformed structure 3D-printed concrete comprising: 1 part by weight of composite cement, 1-2 parts by weight of recycled sand, 0.5 parts by weight of fly ash (FA). 05-0.2 parts by weight, polyvinyl alcohol (PVA) 0.005-0.05 parts by weight, graphene oxide (GO) 0.0002-0.002 parts by weight, steel fibers 0.01-0.05 parts by weight, 0.005-0.02 parts by weight of organic fibers, 0.005-0.01 parts by weight of water reducing agent, 0.005-0.01 parts by weight of coagulation modifier, 0-0.05 parts by weight of mineral mixture and 0 parts by weight of water .3-0.5 parts by weight, said PVA further comprising an oxidizing agent and a catalyst.

Preferably, the composite cement comprises high bellite sulfoaluminate cement (HBSC), Portland cement and gypsum in parts by weight of 1:(0.65-1.25):(0-0.15). It is obtained by mixing in ratio.

Composite cements obtained with this formulation have the characteristics of fast setting and early strength, which combine with the ball lubrication characteristics of FA to contribute to the realization of the corresponding printable and buildable functions of nano-recycled concrete.

Preferably, said reclaimed sand comprises coarse sand, medium sand, fine sand and ultra-fine sand, wherein said medium sand rate is 27%-33%.

More preferably, the coarse sand has a fineness factor of 3.7-3.1 and an average particle size of 0.5 mm or more.

More preferably, the medium sand has a fineness factor of 3.0-2.3 and an average grain size of 0.5 mm-0.35 mm.

More preferably, the fine sand has a fineness factor of 2.2-1.6 and an average grain size of 0.35mm-0.25mm.

More preferably, the ultra-fine sand has a fineness factor of 1.5-0.7 and an average grain size of 0.25 mm or less.

More preferably, the mass ratio of coarse sand, medium sand, fine sand and ultra-fine sand is 1:(1.1-2.0):(1-1.5):(1-1 .5) and can have a good particle size curve after mixing the ingredients in said proportion.

In the present invention, the specific type of reclaimed sand is not particularly limited. In some embodiments, the reclaimed sand is reclaimed sand meeting JC/T2548-2019 specifications obtained after crushing and granulating demolition construction waste or industrial sludge. By using recycled sand, the self-curing effect of nano-recycled concrete slurry is effectively enhanced, and the recycling of solid waste is expanded.

Preferably, the FA is a class I FA with an ignition loss of ≦5% specified in the GB/T 1596-2017 specification, and a favorable ball lubrication effect can be obtained.

Preferably, the PVA is an aqueous PVA solution with an average degree of polymerization of 500-600 and an alcoholysis degree of 88%, and GO is dispersed in the PVA aqueous solution to form a stable GO-PVA prepolymer liquid.

Preferably, the PVA oxidizing agent, PVA catalyst, respectively, are sodium periodate, potassium permanganate or potassium chlorate, concentrated hydrochloric acid, dilute sulfuric acid, dilute nitric acid or boric acid as described in Chinese Patent CN103450489 or CN105885064A. which intercalates the PVA prepolymer into the GO sheet layer structure by an in situ polymerization intercalation process.

Preferably, the GO is a GO powder having a monolayer ratio of ≧90% and an oxygen content of 35-45% or an aqueous dispersion having a concentration of 0.05-10 mg/mL. Calculate the mass of GO in the water dispersion by the ratio and include the water in the corresponding water dispersion in the total amount of water used in the 3D printed concrete.

In the present invention, the specific type of water reducing agent is not particularly limited, and all commercially available products can meet the above-mentioned requirements for producing the coastal profile structure of the present invention. In some specific embodiments, the water reducing agent is one of a polycarboxylic acid superplasticizer, an early-strength polycarboxylic acid superplasticizer, a sodium naphthalenesulfonate superplasticizer, or a melamine resin superplasticizer. Or a combination of multiple optimizations.

Preferably, said coagulation modifier is one of anhydrous sodium sulfate, triethanolamine, nano C—S—H crystal nuclei. The coastal deformed 3D printed concrete according to the present invention facilitates the high-speed setting of concrete with external additives such as solidification modifiers, effectively ensuring the high-speed setting function of nano-recycled concrete.

The present invention employs steel fibers, and the specific source is not particularly limited. Said steel fiber materials generally use the production waste of the steel processing industry. For purchasing convenience and cost saving considerations, in some embodiments of the present invention, the steel fibers are one or more of cutting type steel fibers, shear type steel fibers, milling type steel fibers, hot drawn steel fibers. A combination of species.

In the present invention, the specific source of the organic fibers is also not particularly limited. In some embodiments, the organic fibers are one or more combinations of chopped polyvinyl alcohol fibers, polypropylene fibers, high density polyethylene fibers.

Preferably, said mineral admixture is a combination of one or more of recycled fines, pulverized slag, fly ash, pozzolana or silicon powder. In the present invention, the supply source of raw materials such as the regenerated fine powder is not particularly limited.

Preferably, said water includes, but is not limited to, one of distilled water, deionized water, tap water or electrolyzed water. Engineers can choose according to the construction situation.

In a second aspect of the present invention, there is provided a fabrication process for 3D-printed concrete of coastal profile structures, comprising print-molding said concrete dry-blend material by 3D-printing technology using the 3D-printed concrete raw material according to the first aspect. be done.

Preferably, the specific steps of the manufacturing process of the concrete dry blend material are: preparing PVA, GO and an oxidizing agent into a GO-PVA prepolymer liquid by an in situ polymerization intercalation method; FA; uniformly mixing a water reducing agent, a catalyst, and the GO-PVAH prepolymer liquid, coating the FA with the GO-PVAH prepolymer liquid to form GO-PVAH@FA; dispersing the FA in a solution containing a water reducing agent and a coagulation modifier to form a GO-PVAH@FA suspension;
uniformly mechanically mixing composite cement, reclaimed sand, steel fibers, organic fibers, and a mineral admixture in a silo to form a nano-reclaimed concrete dry blend.

More preferably, the GO-PVAH@FA suspension and the nano-recycled concrete dry blend material are mixed at high speed in a 3D print head, and the printing specifications (speed, flow rate and layer thickness) of the 3D mechanical arm are set. , printing nano-recycled concrete thin layers with different layer thicknesses layer by layer, thereby obtaining a coastal deformed structure.

For the processing process of 3D printing concrete of coastal profile structure according to the present invention, in some embodiments with high effect, the specific operations of the processing process are as follows.

S1: Dissolve the PVA in warm water to prepare an aqueous PVA solution, mix the GO powder or aqueous dispersion with the aqueous PVA solution in the presence of the PVA oxidizing agent, and use an in situ polymerization intercalation process to produce GO A PVA prepolymer is intercalated in the sheet layer structure to obtain a GO-PVA prepolymer liquid.

S2: Adding the FA, a part of the water reducing agent, the PVA catalyst into the GO-PVA prepolymer liquid, and further using a thermosonic process to form a GO-PVA hydrogel (GO-PVAH) outside the surface of the FA particles. to obtain GO-PVAH@FA and seal.

S3: Add the above GO-PVAH@FA to the remaining aqueous solution of the external additive formed by the water reducing agent and the coagulation modifier, and stir uniformly at high speed to obtain a GO-PVAH@FA suspension. and mechanically homogeneously mixing the composite cement, the reclaimed sand, the steel fiber, the organic fiber, and the mineral admixture in a silo to form a nano-reclaimed concrete dry blend.

S4: Determine coastal deformed structural models of different specifications, sizes, material parameters, determine print specification requirements (velocity, flow rate and layer thickness) of 3D mechanical arms, using methods well known in the art GO-PVAH@FA suspension is mixed with nano-recycled concrete dry blend material at high speed by 3D print head, and thin layers of nano-recycled concrete with different layer thickness are printed layer by layer, and finally coastal deformed structures are produced at high speed. manufacture.

In step S1, automatic titration, rotational viscometry, UV-Vis spectrophotometry, and micromorphology methods can be combined to analyze the PVA intercalation efficiency and GO dispersion effect in the GO-PVA prepolymer liquid.

In step S2, the freeze-drying method, UV-Vis spectrophotometry method, TG-DSC simultaneous thermal analysis method, and micromorphology method are respectively combined to determine the equilibrium swelling rate, transparency, degree of structural cross-linking, and fine distribution morphology of GO-PVAH. and tightness can be measured, and the ethanol drainage method, TG-DSC simultaneous thermal analysis method, peel strength method and film thickness measurement method can be combined to determine the total density, water content and organic matter content, and interfacial peeling of GO-PVAH@FA, respectively. Measure resistance and coating layer thickness.

In step S4, the nano-recycled concrete is manufactured using the usual manufacturing methods of nano-recycled concrete for 3D printing, well-known to those skilled in the art, and the nano-recycled concrete rheometer (viscosity coefficient, shear stress, thixotropic loop, thixotropic area) is measured. , a fully automatic concrete setting time and consistency measuring device (setting time, consistency, chronological rheology), etc., to select the type and mixing amount of the corresponding water reducing agent and setting modifier. Characterize the performance of nano-recycled concrete by combining with scaled printability and marine durability (freeze-thaw resistance, chloride ion corrosion resistance, sulfate corrosion resistance) test methods known to those skilled in the art. can be done. Characterize electrochemical parameters such as corrosion potential, polarization resistance, corrosion current density and electrochemical impedance spectrum of steel fibers in combination with methods for characterizing the electrochemical performance of nano-recycled concrete containing steel fibers well known to those skilled in the art be able to. Using methods well known in the art, based on the printing specification requirements (velocity, flow rate and layer thickness) of the 3D mechanical arm, the interlaminar bonding tensile force and interlaminar shear force of nano-recycled concrete thin layers with different layer thicknesses Characterize the performance parameters. The construction quality of nano-recycled concrete with different number of layers and deterioration of interlaminar cohesion under freeze-thaw cycle, ion erosion and sulfate corrosion are investigated by methods such as ultrasonic echo and radar wave non-destructive detection well known to those skilled in the art. can be evaluated.

In a third aspect of the invention there is provided the application of the 3D printed concrete of coastal profile structures according to the first aspect in the manufacture of coastal profile structures.

Preferably, said coastal profile structures include, but are not limited to, manhole covers, rain grate, underground pipes, oval cisterns, subway pipes, honeycomb beams, laminated beams/slabs, and the like.

In order to enable those skilled in the art to understand the technical solutions of the present invention more clearly, the technical solutions of the present invention are described in detail below together with specific embodiments. All raw materials described in the examples below are commercially available products

Example 1
In this example, coastal deformed structure 3D printed concrete is provided, said coastal deformed structure 3D printed concrete is composed of composite cement, recycled sand, fly ash (FA), polyvinyl alcohol (PVA), graphene oxide (GO), It contains steel fibers, organic fibers, water reducing agents, coagulation modifiers, mineral mixtures and water, and the mass ratio of the above components is 1:1:0.05:0.005:0.0002:0.01:0. 005:(0.005-0.01):0.005:0.01:0.3.

The composite cement includes high bellite sulfoaluminate cement (HBSC), Portland cement, and gypsum, and the mass ratio of each component is 1:0.65:0.1. The ball lubrication feature of FA contributed to the realization of the printable and buildable functionality of the corresponding nano-recycled concrete.

The mass ratio of medium-coarse sand, medium sand, fine sand, and ultra-fine sand in the reclaimed sand was 1:1.1:1:1.

The FA was a Class I FA with a loss on ignition ≦5% as specified in the GB/T 1596-2017 specification.

The PVA is an aqueous PVA solution having an average degree of polymerization of 500 to 600 and an alcohol decomposition degree of 88%. The GO was dispersed in the PVA aqueous solution to form a stable GO-PVA prepolymer liquid.

The PVA oxidizing agent and PVA catalyst were sodium periodate and concentrated hydrochloric acid, respectively.

The GO was a GO powder with a monolayer ratio > 90% and an oxygen content of 40%.

The water reducing agent was a polycarboxylic acid superplasticizer.

The coagulation modifier was anhydrous sodium sulfate.

Said steel fibers were cut steel fibers.

The organic fibers were high density polyethylene fibers.

The mineral mixture material was a mixture of recycled fine powder and pulverized slag at a mass ratio of 1:1.

The water was tap water.

Example 2
In this example, coastal deformed structure 3D printed concrete is provided, said coastal deformed structure 3D printed concrete is composed of composite cement, recycled sand, fly ash (FA), polyvinyl alcohol (PVA), graphene oxide (GO), It contains steel fibers, organic fibers, water reducing agents, coagulation modifiers, mineral admixtures and water, and the mass ratio of the above components is 1:2:0.2:0.05:0.002:0.05:0. 02:0.01:0.01:0.05:0.5.

The composite cement included high bellite sulfoaluminate cement (HBSC), Portland cement, and gypsum with a weight ratio of each component of 1:1.25:0.15.

The mass ratio of coarse sand, medium sand, fine sand, and ultra-fine sand in the reclaimed sand was 1:2.0:1.5:1.5.

The FA was a Class I FA with a loss on ignition ≦5% as specified in the GB/T 1596-2017 specification.

The PVA is an aqueous PVA solution having an average degree of polymerization of 500 to 600 and an alcohol decomposition degree of 88%. The GO was dispersed in the PVA aqueous solution to form a stable GO-PVA prepolymer liquid.

The PVA oxidizing agent and PVA catalyst were potassium permanganate and dilute sulfuric acid, respectively.

The GO was a GO powder with a monolayer ratio > 90% and an oxygen content of 35%.

The water reducing agent was an early-strength polycarboxylic acid water reducing agent.

The coagulation modifier was triethanolamine.

The steel fibers were a mixture of shear type steel fibers and milling type steel fibers at a mass ratio of 0.5:1.

The organic fibers were polypropylene fibers.

The mineral admixture was fly ash.

The water was deionized water.

Example 3
In this example, a processing process of 3D printing concrete of coastal profile structure is provided, specifically including steps S1 to S3.

S1: 0.25 kg of PVA was dissolved in 5 L of hot water at a temperature of 70° C. to prepare a PVA aqueous solution having a concentration of 5%, an average degree of polymerization of 500 to 600, and an alcohol decomposition degree of 88%. 0.025 kg of GO powder was mixed with the above PVA aqueous solution under conditions containing sodium periodate (PVA oxidizing agent), and the PVA prepolymer was intercalated into the GO sheet layer structure using an in situ polymerization intercalation process. to obtain a GO-PVA prepolymer liquid.

S2: 1.0 kg of FA, 0.1 kg of polycarboxylic acid superplasticizer, and 0.01 kg of concentrated hydrochloric acid (PVA catalyst) were added to the above GO-PVA prepolymer liquid, and a thermosonic dispersion process using an oil bath ( GO-PVA hydrogel (GO-PVAH) was coated on the outside of the FA particle surface using an oil temperature of 100 ° C., a frequency of 10 kHz, a power of 50 W, and an ultrasonic wave time of 30 min to obtain and seal the GO-PVAH@FA. .

S3: The remaining 0.15 kg of PCA-I type polycarboxylic acid superplasticizer (purchased from Jiangsu Subotech New Materials Co., Ltd.), external additive formed by 0.3 kg of anhydrous sodium sulfate (commercially available). The above GO-PVAH@FA was added to the aqueous solution of the agent, and stirred at high speed and evenly to obtain a GO-PVAH@FA suspension. O-52.5 type Portland cement and 0.5 kg of gypsum), 40 kg of Class II granite reclaimed sand (derived from C40 in Qingdao, crushed construction waste dismantled from 28-year-old concrete structures. and has an average apparent density of 2860 kg/m3) ⁽ composed of 8 kg of coarse sand, 12 kg of medium sand, 10 kg of fine sand and 10 kg of ultra-fine sand), 0.5 kg of fine sand Ground slag powder (originating from the large slag of the blast furnace of this steel with an apparent density of 2930 kg/m ³ and obtained by ball milling) was added with 1.0 kg/m ³ shear shaped steel fibers (length 3- 15 mm, diameter 0.12-0.25 mm, tensile strength ≧2850 MPa, produced by Laiwu Jinhengtong Engineering Materials Co., Ltd.), 0.5 kg/m ³ polyvinyl alcohol fiber (linear density 1.9 g/cm ³ , dry Breaking strength ≥ 11.5 MPa, dry tensile elongation at break ≥ 4.0-9.0%, initial elastic modulus ≥ 280 MPa, length 6 mm, equivalent diameter ≤ 14 μm, Shandong Souyuan New Materials Technology Co., Ltd.), HC-3DPRT type concrete (mortar) was mechanically uniformly mixed in a silo of a 3D printing system (manufactured by Kenken Huazoku (Hangzhou) Science and Technology Co., Ltd.) to form a corresponding nano-recycled concrete dry blend material.
S4: Add the above GO-PVAH@FA suspension and the remaining distilled water calculated at a water-cement ratio of 0.45 to the corresponding nano-recycled concrete dry blend material for 3D printing, and HC-3DPRT type concrete (mortar) was uniformly mixed mechanically in the silo of the 3D printing system to produce a nano-recycled concrete slurry for 3D printing.

Determine the print head specifications of the concrete (mortar) 3D printing system (equivalent diameter of the nozzle 2.5 cm). Yes, in combination with the parameters of the rainwater grid structure (300mm x 450mm x 60mm), the nano-recycled concrete mixture produced above is printed on the coastal rainwater grid structure layer by layer for high-speed manufacturing, interlayer bonding and marine durability. was systematically evaluated.

In step S1, the PVA intercalation efficiency and GO dispersion effect in the GO-PVA prepolymer liquid are shown in FIG. In step S2, the swelling rate of GO-PVAH@FA and the thickness of the coating layer are 30% and 65 μm, respectively; and marine durability are shown in Table 1.

FIG. 1 shows a schematic diagram of the GO-PVA polymerized intercalate and GO-PVAH@FA coating structure, the GO-PVA hydrogel layer is coated on the surface of the FA particles, and the PVA polymer has a GO sheet The layer structure was effectively intercalated, forming positive and negative electric double layers of microcapacitors, effectively enhancing the marine anticorrosion performance of nano-recycled concrete.

Example 4
The specific steps of the manufacturing process of nano-recycled concrete for 3D printing in this example were as follows.

S1: 0.5 kg of PVA was dissolved in 5 L of warm water at a temperature of 80° C. to prepare a PVA aqueous solution having a concentration of 10%, an average degree of polymerization of 500 to 600, and an alcohol decomposition degree of 88%. Under conditions containing potassium permanganate (PVA oxidant), 2 L of 10 mg/mL GO aqueous dispersion was mixed with the above PVA aqueous solution, and PVA pre-precipitation was applied to the GO sheet layer structure using an in situ polymerization intercalation process. The polymer was intercalated to obtain a GO-PVA prepolymer liquid.

S2: 1.5 kg of FA, 0.2 kg of SBT (registered trademark)-510 type early-strength polycarboxylic acid water reducing agent (purchased from Jiangsu Subotech New Materials Co., Ltd.), 0.01 kg of dilute sulfuric acid ( PVA catalyst) is added to the GO-PVA prepolymer liquid, and a thermosonic dispersion process using an oil bath (oil temperature 120 ° C., frequency 20 kHz, power 50 W, ultrasonic wave time 45 min) is adopted to remove the FA particle surface. GO-PVA hydrogel (GO-PVAH) was coated to obtain GO-PVAH@FA and sealed.

S3: The above GO-PVAH@FA is added to the remaining 0.1 kg of SBT (registered trademark)-510 type early-strength polycarboxylic acid water reducing agent and 0.25 kg of an external additive aqueous solution formed of citric acid, Stir fast and evenly to obtain a GO-PVAH@FA suspension, at the same time 25 kg of composite cement (consisting of 12 kg of 525 type HBSC, 12 kg of PO 52.5 Portland cement and 1 kg of gypsum), 35 kg Class II regenerated sand (derived from slag tailing sand of this steel with an apparent density of 3160 kg/m ³ , chemical composition CaO = 35-38%, Fe ₂ O ₃ = 20-24%, SiO ₂ = 18-21 %, Al ₂ O ₃ =5-8%, MgO=5-7%) (composed of 8 kg coarse sand, 12 kg medium sand, 8 kg fine sand and 7 kg ultra-fine sand), 1 kg fly ash (I grade, produced by Qingdao Sifang Power Plant), 0.8 kg/m ³ milling type steel fiber (length 10-60 mm, diameter 0.2-0.6 mm, tensile strength ≥ 850 MPa, produced by Laiwu Jinheng Tong Engineering Materials Co., Ltd. ), 0.6 kg/m ³ polypropylene fiber (linear density 0.91 g/cm ³ , tensile strength ≥ 450 MPa, limit elongation ≥ 10%, elastic modulus ≥ 3500 MPa, length 12 mm, equivalent diameter ≤ 100 μm, Shandong Xiaoyuan New Material Technology Co., Ltd.) was added and mechanically mixed to form the corresponding nano-recycled concrete dry blend material.

S4: Add the above GO-PVAH@FA suspension and the remaining deionized water calculated at a water-cement ratio of 0.42 to the corresponding nano-recycled concrete dry blend material for 3D printing, and HC-3DPRT type concrete (mortar ) was uniformly mixed mechanically in the silo of the 3D printing system to produce a nano-recycled concrete slurry for 3D printing.

Determine the print head specifications of the concrete (mortar) 3D printing system (equivalent diameter of the nozzle 3 cm), the plane printing speed is 6 cm / s, the longitudinal improvement speed is 2 cm / s, the layer thickness is 3 cm, and the coastal manhole Combined with the structural parameters of the cover (Φ600mm × 50mm), the nano-recycled concrete mixture produced above is used to print the cover structure of the coastal manhole layer by layer, and systematically achieve high-speed manufacturing, interlayer bonding and marine durability. evaluated to

In step S2, the swelling ratio of GO-PVAH@FA and the coating layer thickness were 40% and 50 μm, respectively. In step S4, the rapid fabrication, interlayer bonding and marine durability of the 3D printing nano-recycled concrete for circular manhole cover structure are also shown in Table 1.

Example 5
The specific steps of the manufacturing process of nano-recycled concrete for 3D printing in this example were as follows.

S1: Dissolve the above 0.3 kg of PVA in 5 L of hot water at a temperature of 65 ° C. to prepare a PVA aqueous solution having a concentration of 6%, an average degree of polymerization of 500 to 600, and an alcohol decomposition degree of 88%. Under conditions containing potassium chlorate (PVA oxidizing agent), 5 L of GO aqueous dispersion with a concentration of 4 mg/mL was mixed with the above PVA aqueous solution, and the in situ polymerization intercalation process was used to add PVA to the GO sheet layer structure. The prepolymer was intercalated to obtain a GO-PVA prepolymer liquid.

S2: 1.2 kg of FA, 0.15 kg of SBTJM-9 type polycarboxylic acid and melamine resin composite superplasticizer (purchased from Jiangsu Subotech New Materials Co., Ltd.), 0.01 kg of boric acid ( PVA catalyst) was added to the above GO-PVA prepolymer liquid, and a thermosonic dispersion process with an oil bath (oil temperature 100 ° C., frequency 20 kHz, power 50 W, ultrasonic wave time 60 min) was used to disperse GO outside the FA particle surface. - PVA hydrogel (GO-PVAH) was coated to obtain GO-PVAH@FA with a swelling ratio of 50% and a coating layer thickness of 100 μm, respectively, and sealed.

S3: The above GO-PVAH@FA is added to the remaining 0.15 kg of the composite superplasticizer of SBTJM-9 type polycarboxylic acids and melamine resins and 0.3 kg of the external additive aqueous solution formed by tartaric acid, Stir fast and evenly to obtain a GO-PVAH@FA suspension, at the same time 25 kg of composite cement (consisting of 12 kg of 625 type HBSC, 12 kg of PI 42.5 Portland cement and 1 kg of gypsum), 40 kg of Gold tailing class II reclaimed sand (apparent density: 2670 kg/m ³ , obtained by crushing gold tailings of Laizhou Mining Co., Ltd. mainly composed of SiO ₂ and Al ₂ O ₃ and forming particles) (10 kg of coarse sand, 10 kg of medium sand, 10 kg of fine sand and 10 kg of ultra-fine sand), 1 kg of pozzolan (100 mesh, commercially available product), 1.0 kg/m3 of melt ^- drawn shaped steel fiber (long Thickness 13 mm, diameter 0.3 mm, tensile strength ≥ 850 MPa, elastic modulus ≥ 210 GPa, manufactured by Baoding Xin Huo Steel Fiber Manufacturing Co., Ltd.), 0.5 kg/m ³ high-density polyethylene fiber (density 0.97 g/cm ³ , Tensile strength = 2.8-4 N / tex, modulus of elasticity = 91-140 N / tex, elongation = 3.5-3.7%, (produced by Dongguan Suvei Special Cable Co., Ltd.), HC-3DPRT type They were uniformly mixed mechanically in a silo of a concrete (mortar) 3D printing system (manufactured by Kenken Huazoku (Hangzhou) Technology Co., Ltd.) to form a corresponding nano-recycled concrete dry-blended material.

S4: In addition to the GO-PVAH@FA suspension and the remaining electrolyzed water calculated at a water-cement ratio of 0.35 to the corresponding 3D printing nano-recycled concrete dry blend material, HC-3DPRT type industrial grade concrete ( The mortar) was uniformly mixed mechanically in the silo of the 3D printing system to produce a nano-recycled concrete slurry for 3D printing.

Determine the print head specifications (equivalent diameter of the nozzle 5 cm) of the 3D printing system for industrial grade concrete (mortar), the plane printing speed is 4 cm / s, the vertical speed is 1.2 cm / s, and the layer thickness is 1 cm. Yes, in combination with the parameters of the egg-shaped water tank structure (1500mm x 450mm x 300mm), the nano-recycled concrete mixture produced above is printed on the egg-shaped water tank structure layer by layer to achieve high-speed manufacturing, interlayer bonding and marine durability. evaluated systematically.

In step S2, the swelling ratio of GO-PVAH@FA and the coating layer thickness were 40% and 50 μm, respectively. In step S4, the rapid fabrication, interlayer bonding and marine durability of the 3D printing nano-recycled concrete for egg-shaped water tank structure are shown in Table 1.

Example 6
The manufacturing method of this example is the same as that of Example 3, the difference being that in step S3, 20 kg of composite cement is mixed with 10 kg of 525 type HBSC and 10 kg of P.I. It consisted of two parts of O 52.5 Portland cement, without gypsum, with a mix of 0 kg of the corresponding mineral admixture.

In step S2, the swelling ratio of GO-PVAH@FA and the coating layer thickness were 30% and 65 μm, respectively. In step S4, the relevant performance of the nano-recycled concrete for 3D printing is shown in Table 1.

Table 1 Comparative results of performance test of nano-recycled concrete for 3D printing in Examples 3-6

The above descriptions are only preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various modifications and alterations. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (10)

3D printed concrete of coastal deformed structure,
1 part by weight of composite cement, 1-2 parts by weight of recycled sand, 0.05-0.2 parts by weight of fly ash, 0.005-0.05 parts by weight of polyvinyl alcohol, 0.0002-0.002 parts by weight of graphene oxide, Steel fiber 0.01-0.05 parts by weight, organic fiber 0.005-0.02 parts by weight, water reducing agent 0.005-0.01 parts by weight, coagulation modifier 0.005-0.01 parts by weight, mineral 3D printed concrete for coastal deformed structures, characterized in that it is composed of 0-0.05 parts by weight of a mixture and 0.3-0.5 parts by weight of water, and said PVA further comprises an oxidizing agent and a catalyst. The composite cement is obtained by mixing high berite sulfoaluminate cement, Portland cement, and gypsum in a weight part ratio of 1:(0.65-1.25):(0-0.15). 3D printed concrete of coastal profile structure according to claim 1. The recycled sand includes coarse sand, medium sand, fine sand and ultra-fine sand, and the medium sand ratio is 27% to 33%,
Preferably, the coarse sand is coarse sand having a fineness coefficient of 3.7-3.1 and an average particle size of 0.5 mm or more,
Preferably, the medium sand has a fineness coefficient of 3.0-2.3 and an average particle diameter of 0.5 mm-0.35 mm,
Preferably, the fine sand has a fineness factor of 2.2-1.6 and an average particle size of 0.35 mm-0.25 mm,
Preferably, the ultra-fine sand is ultra-fine sand having a fineness coefficient of 1.5 to 0.7 and an average particle size of 0.25 mm or less,
Preferably, the mass ratio of coarse sand, medium sand, fine sand and ultra-fine sand is 1:(1.1-2.0):(1-1.5):(1-1 .5) The 3D printed concrete of coastal profile structure according to claim 1, characterized in that: The FA is a class I FA with ignition loss ≤ 5% specified in GB / T 1596-2017 specifications,
Alternatively, the PVA is an aqueous PVA solution having an average degree of polymerization of 500 to 600 and a degree of alcohol decomposition of 88%,
or the PVA oxidizing agent, the PVA catalyst is one of sodium periodate, potassium permanganate or potassium chlorate, concentrated hydrochloric acid, dilute sulfuric acid, dilute nitric acid or boric acid, respectively;
Alternatively, the GO is a GO powder having a monolayer ratio of ≧90% and an oxygen content of 35 to 45% or an aqueous dispersion having a concentration of 0.05 to 10 mg/mL. 3D printed concrete of coastal deformed structure. The water reducing agent is one or more of a polycarboxylic acid superplasticizer, an early-strength polycarboxylic acid superplasticizer, a sodium naphthalenesulfonate superplasticizer, or a melamine resin superplasticizer,
Alternatively, the 3D printed concrete of coastal deformed structure according to claim 1, characterized in that the solidification modifier is one of anhydrous sodium sulfate, triethanolamine, and nano-C—S—H crystal nuclei. . the steel fibers are one or a combination of cutting type steel fibers, shear type steel fibers, milling type steel fibers, hot-draw type steel fibers,
Or, the 3D printed concrete of coastal profile structure according to claim 1, characterized in that the organic fibers are one or more combinations of chopped polyvinyl alcohol fibers, polypropylene fibers, high-density polyethylene fibers. The mineral admixture is one or more of recycled fines, pulverized slag, fly ash, pozzolan or silicon powder, and
Alternatively, the water includes, but is not limited to, one of distilled water, deionized water, tap water, or electrolyzed water. 3D printed concrete of coastal deformed structure, characterized in that the processing process prints and molds the concrete dry blend material by 3D printing technology using the 3D printed concrete raw material according to any one of claims 1 to 7. Machining process. The specific steps of the manufacturing process of the concrete dry blend material are:
Preparing PVA, GO and an oxidizing agent into a GO-PVA prepolymer liquid by an in-situ polymerization intercalation method, and uniformly mixing FA, a water reducing agent, a catalyst and the GO-PVAH prepolymer liquid. and coating the GO-PVAH prepolymer liquid on the outside of FA to form GO-PVAH@FA; Forming an FA suspension, mechanically homogeneously mixing composite cement, reclaimed sand, steel fibers, organic fibers, and a mineral admixture in a silo to form a nano-reclaimed concrete dry blend. and
Preferably, the GO-PVAH@FA suspension and the nano-recycled concrete dry blend material are mixed at high speed in the 3D print head, and the printing specifications of the 3D mechanical arm are set to form thin layers of nano-recycled concrete with different layer thicknesses. The working process of 3D printed concrete of coastal profile structure according to claim 8, characterized in that the coastal profile structure is printed layer by layer, thereby obtaining the coastal profile structure. Suitably, said coastal profile structures include, but are not limited to, manhole covers, rain grate, underground pipes, oval cisterns, subway pipes, honeycomb beams, laminated beams/slabs, etc.
Application of 3D printed concrete of coastal profile structures according to any of claims 1-7 in the production of coastal profile structures.

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