Nanomaterial reinforced building 3d printing material and method of making

Abstract

The application relates to a kind of nanomaterial reinforced building 3D printing materials and its preparation method, the 3D printing material includes: high-strength concrete, including inert filler of micron level, cementitious material mixed with nanoscale silica gel and steel fiber;For adding to the high-strength concrete to make the high-strength concrete meet the printability of additive, the additive includes superplasticizer and hydroxypropyl methyl cellulose.The 3D printing material of the application has higher strength than traditional 3D printing material, while taking into account 3D printability.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of 3D printing technology, in particular to a kind of nano material reinforced building 3D printing material and its preparation method. BACKGROUND

[0002] 3D printing (3DP) is a kind of rapid prototyping technology, also known as additive manufacturing, which is a kind of technology that uses powdered metal, plastic or concrete and other adhesive materials to construct objects layer by layer based on 3D model files. Its main features are rapid prototyping, reducing material waste, eliminating templates, high design freedom, and significantly reducing carbon emissions. It is an innovative, environmentally friendly and efficient new component manufacturing method.

[0003] 3D printing ink refers to the adhesive material used in 3D printing technology to print the components. In building printing, 3D printing ink usually uses a special concrete (i.e. 3D printing concrete). Suitable 3D printing concrete needs to have appropriate fluidity, buildability, interlayer bonding strength and setting time to meet the printability. The advantage of 3D printing concrete material is that it saves one-time template material, reduces labor cost and can print high artistic irregular structures.

[0004] Low-strength printing materials are prone to swelling phenomenon: when the stress is small and the flow is slow, the adhesive resistance of the colloidal paste is small due to the sliding and flowing action of water. If stirred vigorously, the ions in the dense arrangement will be disturbed at once and become a porous loose arrangement structure. This is because the original water cannot fill the gap between the particles, and there is no sliding action of the water layer between the particles, so the adhesive resistance will suddenly increase, and even lose the property of flow. Because the particles become loose arrangement structure under strong shear action, the apparent volume increases, so it is called swelling phenomenon. Therefore, the innovation of irregular structure is often limited to the strength of the printing material. Low-strength printing materials will lead to an increase in the cross-sectional area of the design level, ultimately making the printed structure appear bulky and heavy in appearance, which seriously reduces the artistic nature of 3D printing concrete components. Therefore, enhancing the mechanical properties of 3D printing materials has become a problem to be solved. SUMMARY

[0005] To solve the above problems, the present application provides a kind of nano material reinforced building 3D printing material and its preparation method, the 3D printing material has higher strength than traditional 3D printing material, while considering 3D printability.

[0006] The present application is realized by the following scheme, a kind of nano material reinforced building 3D printing material, comprising:

[0007] High-strength concrete, including micron-sized inert fillers, cementitious materials mixed with nanoscale silica gel, and steel fibers;

[0008] An additive for being added to the high-strength concrete to make the high-strength concrete meet the printability, the additive including a superplasticizer and hydroxypropyl methylcellulose.

[0009] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the cementitious material includes Portland cement and sulphoaluminate cement.

[0010] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the micron-sized inert fillers include primary fly ash and S95 silica fume.

[0011] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the primary fly ash in the high-strength concrete is 0.15-0.2 parts by weight, the S95 silica fume is 0.2-0.4 parts by weight, the nanoscale silica gel is 0.01-0.03 parts by weight, the Portland cement is 1 part by weight, the sulphoaluminate cement is 0.02-0.05 parts by weight, and the steel fiber is 0.2-0.3 parts by weight, wherein the weight of the nanoscale silica gel is the weight excluding the water content thereof.

[0012] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the high-strength concrete further includes 1.6-2.0 parts by weight of natural river sand and 0.25-0.3 parts by weight of water.

[0013] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the superplasticizer in the additive is 0.01-0.03 parts by weight, and the hydroxypropyl methylcellulose is 0.001-0.005 parts by weight.

[0014] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the micron-sized inert fillers further include any one of slag powder, recycled concrete fine, metakaolin, and ultrafine calcium carbonate, or a combination of any two or more thereof.

[0015] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the length of the steel fiber ranges from 5 mm to 15 mm.

[0016] The further improvement of the nanomaterial-enhanced building 3D printing material lies in that the concentration of the nanoscale silica gel in the high-strength concrete is not more than 40%.

[0017] The application also provides a preparation method of the nanomaterial reinforced building 3D printing material, comprising the steps of: providing the high-strength concrete and the additive as described in any one of the above, adding the additive into the high-strength concrete, mixing and fully stirring to make the high-strength concrete meet the printability.

[0018] In one aspect, based on the maximum packing density theory, the micron-sized inert filler and the nanometer-sized silica gel are added into the millimeter-sized river sand and other aggregates, the traditional dense packing design is deepened to the nanometer level, the multi-scale synergistic strengthening is realized, and the high-strength concrete is further obtained by adding the steel fiber as the structural reinforcing body and the interlayer “pinning” material. In another aspect, by adding the superplasticizer and the hydroxypropyl methylcellulose and other additives, the setting time and the rheological property and other key parameters of the high-strength concrete are changed, so that the high-strength concrete has the printability. The problems of the traditional 3D printing material, such as insufficient strength and fragile structure of the printed part, are solved. DETAILED DESCRIPTION

[0019] In order to solve the problems of the traditional 3D printing material, such as insufficient strength and fragile structure of the printed part, the application provides a nanomaterial reinforced building 3D printing material and a preparation method thereof. The 3D printing material has higher strength than the traditional 3D printing material, and has the 3D printability. The nanomaterial reinforced building 3D printing material and the preparation method thereof are further described below with specific examples.

[0020] The nanomaterial reinforced building 3D printing material comprises: a high-strength concrete, including a micron-sized inert filler, a cementitious material mixed with nanometer-sized silica gel and steel fiber; and an additive for adding to the high-strength concrete to make the high-strength concrete meet the printability, the additive comprising a superplasticizer and hydroxypropyl methylcellulose.

[0021] Specifically, the cementitious material is preferably a silicate-sulphoaluminate composite cement system, including silicate cement and sulphoaluminate cement, and the nanometer-sized silica gel is added to the cementitious material in a water sol measurement, and the concentration of the nanometer-sized silica gel is preferably not more than 40% to ensure its dispersion effect. The micron-sized inert filler includes first fly ash and S95 silica ash, and can also select any one of slag powder, recycled concrete fine, metakaolin and ultra-fine calcium carbonate, or a combination of any two or more. The length of the steel fiber ranges from 5mm to 15mm. Since a pump is usually used to pump the 3D printing material during 3D printing, in order to reduce the friction loss of the pump as much as possible, the steel fiber is a 5mm long copper-plated steel fiber in this embodiment, which can not only improve the hardening tensile strength of the printed component and the interlayer friction, but also reduce the friction loss of the pump as much as possible. In addition, the high-strength concrete further comprises quartz sand (such as natural river sand) and water.

[0022] The present embodiment is based on the maximum packing density theory, adding micron-sized inert fillers and nanoscale silica gel to millimeter-sized river sand and other aggregates, and further deepening the traditional dense packing design to the nanoscale level, achieving multi-scale synergistic reinforcement, and improving the mechanical properties and durability of the material. At the same time, by adding steel fibers as structural reinforcement and interlayer "pinning" materials, high-strength concrete is obtained. However, this high-strength concrete does not meet the printability requirements and cannot be directly used as a 3D printing material, for the following reasons:

[0023] 1. Pumpability: The high viscosity of high-strength concrete results in high pumping pressure, and the steel fibers can cause wear and tear to the plastic sleeves and other weak links of the pumping machine.

[0024] 2. Extrudability: 3D printing concrete requires Bingham plastic fluid properties, while high-strength concrete belongs to the dilatant fluid type, which is not conducive to extrusion molding.

[0025] 3. Buildability: High-strength concrete has excessive fluidity and belongs to self-compacting concrete. For 3D printing, high-strength concrete hardens slowly and is difficult to achieve layer-by-layer accumulation.

[0026] The three concepts of pumpability, extrudability, and buildability are combined into printability. In this embodiment, additives are added to change the rheological properties and setting time of high-strength concrete, while also considering key parameters such as strength, to overcome the above problems and meet the printability requirements. Specifically: by increasing the hydration rate of cementitious materials, the material can be stably accumulated without collapse during long-term printing; by adding superplasticizers and hydroxypropyl methylcellulose and other additives to change the setting time and rheological properties of high-strength concrete, the high-strength concrete has printability; in addition, by controlling the length of the steel fibers, the wear and tear of the steel fibers to the weak links of the pumping machine is minimized.

[0027] A preferred raw material ratio example is provided below, which can obtain a high-strength 3D printing material that meets the composite requirements, as shown in Table 1:

[0028] Table 1: Raw materials and ratio table

[0029] Raw materials Specific gravity Class 1 fly ash 0.15～0.2 S95 silica fume 0.2～0.4 Nanoscale silica gel (Si02) 0.01～0.03 PO425 cement 1 Sulphoaluminate cement 0.02～0.05 Steel fibres 0.2～0.3 Natural river sand 1.6～2.0 Water 0.25～0.3 Superplasticizer 0.01～0.03 Hydroxypropyl methylcellulose 0.001～0.005

[0030] The 3D printing material comprises 0.15-0.2 parts by weight of primary fly ash, 0.2-0.4 parts by weight of S95 silica ash, 0.01-0.03 parts by weight of nano-silica gel, 1 part by weight of Portland cement (PO425 cement), 0.02-0.05 parts by weight of sulphoaluminate cement, 0.2-0.3 parts by weight of steel fiber, 1.6-2.0 parts by weight of natural river sand, and 0.25-0.3 parts by weight of water, wherein the weight of the nano-silica gel is the weight excluding the water content thereof. The 3D printing material further comprises 0.01-0.03 parts by weight of superplasticizer and 0.001-0.005 parts by weight of hydroxypropyl methylcellulose and other additives.

[0031] The 3D printing material obtained by using the above raw materials and proportions has a strength of 6 MPa at 7 days and a strength of 120 MPa at 28 days, while the strength of ordinary 3D printing concrete is between 20 MPa and 60 MPa. It can be seen that the 3D printing material of the present application can greatly improve the strength of the 3D printed component, thereby saving materials and improving the degree of freedom of artistic design of the component.

[0032] Of course, the above is only a preferred embodiment, and in actual application, different types of additives or the proportions of the raw materials can be selected to adapt to different printing requirements and material performance requirements.

[0033] A preparation method of a nano-material reinforced building 3D printing material, comprising the steps of: providing high-strength concrete and additives as described above, adding the additives to the high-strength concrete, the above-mentioned raw materials can be added in a certain order in sequence or simultaneously, mixed and fully stirred to ensure uniform dispersion of the raw materials, and finally obtaining high-strength concrete that meets the printability, which is used as a 3D printing material, thereby breaking through the problem of insufficient strength of traditional 3D printing materials and weak structure of printed components.

[0034] The above embodiments have been described in detail, and those skilled in the art can make various changes to the present application according to the above description. Therefore, some details in the embodiments should not constitute a limitation on the present application, and the scope of protection of the present application will be defined by the appended claims.

Claims

1. A nanomaterial-reinforced 3D printing material for buildings, characterized in that, include: High-strength concrete comprises micron-sized inert filler, a cementing material containing 0.01 to 0.03 parts by weight of nano-sized silica gel, and 0.2 to 0.3 parts by weight of steel fiber. The micron-sized inert filler comprises 0.15 to 0.2 parts by weight of grade I fly ash and 0.2 to 0.4 parts by weight of S95 silica fume. The cementing material comprises 1 part by weight of silicate cement and 0.02 to 0.05 parts by weight of sulfoaluminate cement. The weight of the nano-sized silica gel is the weight after deducting its own water content. An admixture used to add to the high-strength concrete to make the high-strength concrete printable, the admixture comprising 0.01 to 0.03 parts by weight of a superplasticizer and 0.001 to 0.005 parts by weight of hydroxypropyl methylcellulose.

2. The nanomaterial-reinforced 3D printing material for buildings as described in claim 1, characterized in that, The high-strength concrete also includes 1.6 to 2.0 parts by weight of natural river sand and 0.25 to 0.3 parts by weight of water.

3. The nanomaterial-reinforced 3D printing material for buildings as described in claim 1, characterized in that, The micron-scale inert filler also includes any one of slag powder, recycled concrete fines, metakaolin, and ultrafine calcium carbonate, or any combination of two or more of them.

4. The nanomaterial-reinforced 3D printing material for buildings as described in claim 1, characterized in that, The length of the steel fiber ranges from 5mm to 15mm.

5. The nanomaterial-reinforced 3D printing material for buildings as described in claim 1, characterized in that, The concentration of the nanoscale silica gel in the high-strength concrete does not exceed 40%.

6. A method for preparing a nanomaterial-reinforced 3D printing material for buildings, characterized in that, The method includes the following steps: providing high-strength concrete and admixtures as described in any one of claims 1 to 5, adding the admixtures to the high-strength concrete, mixing and stirring thoroughly to ensure that the high-strength concrete meets the requirements for printability.