WO2022078100A1

WO2022078100A1 - Method for testing bendability and extensibility of 3d-printing cementitious material

Info

Publication number: WO2022078100A1
Application number: PCT/CN2021/116148
Authority: WO
Inventors: 董赛阳; 吴杰; 朱敏涛; 卞成辉; 周强; 张玉鹏
Original assignee: 上海建工建材科技集团股份有限公司; 上海同舜混凝土有限公司
Priority date: 2020-10-13
Filing date: 2021-09-02
Publication date: 2022-04-21
Also published as: CN112213205B; CN112213205A

Abstract

Provided is a method for testing the bendability and extensibility of a 3D-printing cementitious material, comprising the following steps: step 1: bendability testing of a cementitious material; an extrusion apparatus (1) extrudes a cementitious material printed strip (2) on the table (7) according to a defined folded-line path or curved-line path; the value of the folded-line angle (3) of the folded-line-shaped printed strip (2) decreases gradually in a gradient as the number of measurements increases; the value of the folded-line angle (3) when the printed strip (2) cracks at the folded-line angle (3) is recorded; the curvature value of the curved-line angle (4) of the curved-line-shaped printed strip (2) increases gradually in a gradient as the number of measurements increases; the curvature value of the printed strip (2) when it cracks at the curved-line angle (4) is recorded; step 2: comparison of the bendability of cementitious materials; step 3: extensibility testing of a cementitious material. Testing and evaluating the capacity of a 3D-printing cementitious material to be used to print a structure having an inclination or extension, facilitates quantification of the performance of a printed material to be suitable for printing, and has a guiding role in the formulation of 3D-printing cementitious materials.

Description

Test method for bendability and extension of 3D printed cement-based materials

technical field

The invention belongs to the technical field of architectural 3D printing, and particularly relates to a method for testing the flexibility and extension of 3D printing cement-based materials.

Background technique

In recent years, architectural 3D printing technology has begun to develop. Architectural 3D printing technology is an interdisciplinary digital construction technology. The requirements for building materials are different from the past. The materials used for architectural 3D printing are mainly cement-based materials. With the changes in the performance requirements of cement-based materials and different application scenarios, the relevant testing methods for materials also need to be updated and supplemented. In this regard, scholars at home and abroad have carried out a lot of research work, and have formulated or are formulating some performance testing standards for 3D printing cement-based materials. , the stackability after extrusion from the nozzle and the stability after stacking.

If the 3D printing cement-based materials are not properly formulated, cracks are likely to appear at the corners of the printing, which will affect the printing quality, but there is no relevant testing method or standard for this material quality problem; the architectural 3D printing technology has been able to print a certain slope. However, there is currently no testing method or standard for whether cement-based materials are suitable for printing inclined structures or protruding structures, and it is impossible to judge whether cement-based materials are suitable for printing inclined structures or protruding structures.

SUMMARY OF THE INVENTION

In view of the problems existing in the prior art, the present invention provides a method for testing the flexibility and extension of 3D printed cement-based materials. Evaluation.

To achieve the above object, the present invention adopts the following technical solutions:

The invention provides a method for testing the flexibility and extension of 3D printing cement-based materials, comprising the following steps:

Step 1. Bendability test of cement-based material; the extrusion device extrudes the cement-based material printing strip on the workbench according to the specified polyline path or curve path, and the polyline corner value of the polyline-shaped printing strip is gradient with the increase of the number of inspections. Gradually decrease, record the corner value of the polyline when cracks appear at the corners of the polyline, and the curvature value of the curve corners of the curvilinear print bar increases gradually with the increase of the number of inspections. Record when cracks appear in the corner of the print bar The curvature value of ;

Step 2: Comparison of the flexibility of cement-based materials; set the polyline corner value of the polyline-shaped print strip or the curvature value of the curve corner of the curve-shaped print strip, measure and record the crack width or multiple crack widths at the corner vertices of the polyline-shaped print strip. The crack width of the curved cement-based printing strip at the specified curvature is arranged according to the crack width from small to large;

Step 3: Test of the extrudability of the cement-based material; the extrusion device extrudes the cement-based material printing strip on the worktable with the groove, the printing strip spans the groove, and the width of the groove along the length direction of the printing strip and the printing strip are recorded. The sag distance of the strip at the groove is used to characterize the stick-out of the cement-based material.

As a preferred technical solution, in step 1 or step 3, keep the worktable still, and complete the printing of the print strip with the specified path through the movement of the extrusion device, or keep the extrusion device stationary, and complete the specified path through the movement of the worktable. The printing work of the printing strip of the path is completed, or the printing work of the printing strip of the specified path is completed by the joint movement of the extrusion device and the worktable.

As a preferred technical solution, in the second step, the bendability of the cement-based material is characterized by the crack depth of the polyline-shaped printing strip at the corner vertex or the crack depth of the curved cement-based printing strip at a specified curvature.

As a preferred technical solution, when the cement-based material is extruded, the nozzle diameter, nozzle shape, extrusion speed of the printing strip, temperature and humidity of the test environment are kept the same.

As a preferred technical solution, in the third step, the sagging distance of the printing strip at the groove is equal to the distance between the upper surface of the printing strip on the worktable and the upper surface of the lowest position of the printing strip or the upper surface of the worktable and the printing strip. The distance between the lower surfaces at the lowest point.

As a preferred technical solution, in the third step, the width of the groove on the worktable can be adjusted along the length direction of the printing strip, the printing strip is perpendicular to the edge of the groove, and the maximum groove width is maintained through the printing strip without breaking. The width characterizes the extension of the cement-based material.

As a preferred technical solution, in the first step, the maximum value of the corner value of the broken line of the broken line-shaped printing strip is 180 degrees, the minimum value is 10 degrees, and the descending gradient is 10 degrees.

As a preferred technical solution, in the first step, the minimum curvature value of the curve corner of the curved printing bar is 1 dm ^-1 , the maximum curvature value is 10 dm ^-1 , and the ascending gradient is 0.5 dm ^-1 .

Compared with the prior art, the beneficial effects of the present invention are:

(1) The present invention characterizes the flexibility of the material by measuring the bendable angle of the 3D printed cement-based material printing strip or the crack width at the apex of the bending angle under the same bending angle, and the bendability of the obtained 3D-printed cement-based material is tested. It can be used as an important parameter for the printing quality of the material.

(2) In the present invention, the protruding property of the cement-based material is characterized by measuring the sagging distance of the 3D printed cement-based material printing strip over the groove. Important parameters of the protruding structure.

(3) The 3D printing cement-based material bending and extruding test method disclosed in the present invention can easily and quantitatively evaluate the bending and extruding properties of the material respectively, and the 3D printing cement-based material has the ability to print a structure with an inclination or a protruding property. Testing and evaluation can help to quantify the performance of printing materials and guide the formulation of 3D printing cement-based materials.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention. For those of ordinary skill in the art, other drawings can also be obtained from these drawings without creative efforts.

FIG. 1 is a schematic diagram of the method for testing the bending fold line of the 3D printing cement-based material of the present invention.

FIG. 2 is a schematic diagram of the test method for the bending curve of the 3D printed cement-based material of the present invention.

FIG. 3 is a schematic diagram of the test method for the extrudability of the 3D printed cement-based material of the present invention.

The reference numerals are specifically described as follows: extrusion device 1 , cement-based material printing strip 2 , folded line corner 3 , curved corner 4 , sagging distance 5 , groove 6 , and worktable 7 .

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, but not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

Example 1

This embodiment provides a method for testing the bending of a 3D printed cement-based material with a broken line, to test the bending of the cement-based material A.

Add the cement-based material A to the extrusion device 1, the extrusion device 1 moves on the worktable, and extrudes the cement-based material A according to the specified broken line path to form the cement-based material printing strip 2. The angle of the broken line angle 3 is from 180°. The gradient decreases to 10° in turn, decreasing by 10° each time. It is found that when the angle of the broken line corner 3 of the cement-based material A decreases to 80°, cracks appear at the broken line corner 3, so it is concluded that the bendable angle of the cement-based material A is 90°.

Example 2

This embodiment provides a method for testing the bending properties of 3D printed cement-based materials, and compares the bending properties of cement-based material B, cement-based material C, and cement-based material D.

Add the cement-based material B to the extrusion device 1, the extrusion device 1 moves on the worktable, and extrudes the cement-based material B according to the specified broken line path to form the cement-based material printing strip 2, and the angle of the broken line angle 3 is 60° , After the printing is completed, the crack width of the cement-based material B at the corner 3 of the broken line is measured to be 1.1 mm. The bending properties of the cement-based material C and the cement-based material D are tested in the same way. The crack width at the corner 3 of the broken line is 0.5mm, while the cement-based material D has no cracks at the corner 3 of the broken line, so it is concluded that the bending properties of the cement-based material B, the cement-based material C and the cement-based material D are from good to bad. The order is: cement-based material D> cement-based material C> cement-based material B.

Example 3

This embodiment provides a 3D printing cement-based material bendability curve testing method to test the bendability of the cement-base material E.

Add the cement-based material E to the extrusion device 1, and the extrusion device 1 moves on the workbench to extrude the cement-based material E according to the prescribed curve path to form the cement-based material printing strip 2. The size of the curvature of the curve corner 4 ranges from 1dm ^- From ¹ to 5dm ^-1 , the gradient increases in turn, and each time increases by 0.5dm ^-1 . It is found that when the curvature of the curve corner 4 of the cement-based material E increases from 3.5dm ^-1 to 4dm ^-1 , cracks appear in the curve corner 4, so we get It is concluded that the bendable curvature of the cement-based material E is 3.5 dm ^-1 .

Example 4

This embodiment provides a 3D printing cement-based material bending curve test method, and compares the bending properties of cement-based material F, cement-based material G, and cement-based material H.

Add the cement-based material F to the extrusion device 1, and the extrusion device 1 moves on the worktable to extrude the cement-based material F according to the prescribed curve path to form the cement-based material printing strip 2. The curvature of the curve corner 4 is 4.5dm. ^-1 , after the printing is completed, the crack width of the cement-based material F at the corner 4 of the curve is measured to be 0.3 mm. The bending properties of the cement-based material G and the cement-based material H are tested in the same way, and the cement-based material is measured. The crack width of G at the corner 4 of the curve is 0.8 mm, while the cement-based material H has no cracks at the corner 4 of the curve, so it is concluded that the bending properties of the cement-based material F, the cement-based material G and the cement-based material H are excellent The descending order is: cement-based material H> cement-based material F> cement-based material G.

Example 5

This embodiment provides a method for testing the extrudability of 3D printing cement-based materials, and tests and compares the extrudability of cement-based material I and cement-based material J.

The cement-based material 1 is added to the extrusion device 1, and the extrusion device 1 moves on the workbench 7 to extrude the cement-based material I according to a prescribed curve path to form a cement-based material printing strip 2, and the cement-based material printing strip 2 spans the concave cavity. Slot 6, under the action of gravity, the cement-based material printing strip 2 sags in the groove 6, measure the distance from the upper surface of the table 7 to the lowest point of the cement-based material printing strip 2 in the groove 6, that is, the sagging distance 5, The sagging distance 5 of the measured cement-based material I is 23.5mm, and the same method is used to test the extension of the cement-based material J, and the measured sag distance 5 is 10.8mm. The extrudability of cement-based material J is considered to be better.

Although the above embodiments have specifically described the present invention, it should be understood by those skilled in the art that modifications or improvements can be made based on the disclosure of the present invention without departing from the spirit and scope of the present invention. and modifications are within the spirit and scope of the present invention.

Claims

A method for testing the flexibility and extension of 3D printing cement-based materials, comprising the following steps:

Step 1. Bendability test of cement-based material; the extrusion device extrudes the cement-based material printing strip on the workbench according to the specified polyline path or curve path, and the polyline corner value of the polyline-shaped printing strip is gradient with the increase of the number of inspections. Gradually decrease, record the corner value of the polyline when cracks appear at the corner of the polyline, and the curvature value of the curve corner of the curve-shaped print bar increases gradually with the increase of the number of inspections. Record when cracks appear at the corner of the curve. The curvature value of ;

Step 2: Comparison of the flexibility of cement-based materials; set the polyline corner value of the polyline-shaped print strip or the curvature value of the curve corner of the curve-shaped print strip, measure and record the crack width or multiple crack widths at the corner vertices of the polyline-shaped print strip. The crack width of the curved cement-based printing strip at the specified curvature is arranged according to the crack width from small to large;

Step 3: Test of the extrudability of the cement-based material; the extrusion device extrudes the cement-based material printing strip on the worktable with the groove, the printing strip spans the groove, and the width of the groove along the length direction of the printing strip and the printing strip are recorded. The sag distance of the strip at the groove is used to characterize the stick-out of the cement-based material.
The method for testing the flexibility and extension of 3D printing cement-based materials according to claim 1, wherein in the step 1 or step 3, the worktable is kept stationary, and the specified path is completed by the movement of the extrusion device or keep the extrusion device stationary, complete the printing work of the printing strip with the specified path through the movement of the worktable, or complete the printing work of the printing strip with the specified path through the joint movement of the extrusion device and the worktable.
The method for testing the flexibility and extension of 3D printing cement-based materials according to claim 1, wherein in the second step, the depth of cracks at the corner vertex of the polyline-shaped printing strip or the curve-shaped cement-based The crack depth of the printed strip at a specified curvature characterizes the bendability of the cementitious material.
The method for testing the flexibility and extension of a 3D printing cement-based material according to claim 1, wherein the cement-based material maintains the nozzle diameter, nozzle shape, extrusion speed of the printing strip, and test environment when the cement-based material is extruded. temperature and humidity are the same.
The method for testing the flexibility and extension of 3D printing cement-based materials according to claim 1, wherein in the third step, the sagging distance of the printing strip at the groove is equal to the printing strip on the workbench The distance from the top surface to the bottom surface of the print bar or the distance from the top surface of the table to the bottom surface of the print bar bottom.
The method for testing the flexibility and extension of 3D printing cement-based materials according to claim 1, wherein in the step 3, the width of the groove on the worktable is adjustable along the length direction of the printing strip, and the printing The strips are perpendicular to the groove edges, and the extrudability of the cement-based material is characterized by the maximum width of the grooves without breaking the printed strips.
The method for testing the flexibility and extensibility of 3D printing cement-based materials according to claim 1, wherein in the step 1, the maximum value of the corner value of the folding line of the polygonal printing strip is 180 degrees, and the minimum value is 180 degrees. is 10 degrees, and the descending gradient is 10 degrees.
The method for testing the flexibility and extensibility of 3D printing cement-based materials according to claim 1, wherein in the first step, the minimum curvature value of the curved corner of the curved printing strip is 1 dm -1 , and the maximum curvature value is 1 dm-1. The value is 10dm -1 and the ascent gradient is 0.5dm -1 .