CN114434590B

CN114434590B - 3D printing permeable concrete structure and preparation method thereof

Info

Publication number: CN114434590B
Application number: CN202210157344.8A
Authority: CN
Inventors: 吕奇峰; 辛格; 朱平华; 宗美容; 戴鹏飞; 陈安国; 阚德远; 李海潮; 罗浩然
Original assignee: Changzhou University
Current assignee: Changzhou University
Priority date: 2022-02-21
Filing date: 2022-02-21
Publication date: 2023-12-01
Anticipated expiration: 2042-02-21
Also published as: CN114434590A

Abstract

A3D printing permeable concrete structure and a preparation method thereof belong to the field of building materials. The 3D printing permeable concrete structure comprises a mortar layer and a coarse aggregate layer which are arranged in a staggered manner, wherein the bottommost layer and the topmost layer are the mortar layer, the mortar layer comprises 40.2-45.1 parts of cement, 40.2-45.1 parts of sand, 13.8-15.9 parts of tap water, 0.03-0.05 part of water reducer, 0.03-0.05 part of retarder and 0.04-0.06 part of hydroxypropyl methyl cellulose according to the mass part ratio, and the coarse aggregate layer is coarse aggregate with the particle size of 10-20 mm. The invention provides an automatic manufacturing method of novel pervious concrete, which saves manufacturing time and labor cost, improves the water permeability of the concrete, is widely applied, and can relieve urban waterlogging and urban heat island effect which often occur in urban construction.

Description

3D printing permeable concrete structure and preparation method thereof

Technical Field

The invention belongs to the field of building materials, and relates to a 3D printing permeable concrete structure and a preparation method thereof.

Background

In urban construction, a large amount of concrete is not permeable, which not only easily causes urban waterlogging in heavy rainy days, but also causes inconvenient walking even in small rainy days due to a small amount of water accumulation on the ground. In addition, the heat absorption rate of the waterproof concrete is larger, so that the temperature of the surrounding air can be raised faster, and the urban heat island effect is caused. To alleviate these problems, pervious concrete has been used. The conventional permeable concrete is generally formed by mixing single-graded coarse aggregate and a small amount of binder (cement or asphalt), and has the main problems of low strength, easy blocking of pores and higher construction labor cost.

3D printing is a new material forming process, which is an additive manufacturing (Additive manufacturing) method, and has the advantage of saving materials compared with the traditional grinding and cutting process. The manufacture of the traditional concrete structural member is also additive, but the 3D printed concrete avoids the use of templates and labor, and saves time and labor cost. However, 3D printed concrete has high requirements for materials, and is currently only suitable for small-particle-size fine aggregate mortar, while large-particle-size coarse aggregate used for pervious concrete cannot be used because of easy material discontinuity and blockage of printing machines, which also makes 3D printing of conventional pervious concrete very difficult.

Disclosure of Invention

The technical problems to be solved are as follows: aiming at the problems in the prior art, the invention provides a 3D printing permeable concrete structure and a preparation method thereof, wherein the 3D printing permeable concrete is large-particle-size coarse aggregate permeable concrete, and the method can improve the strength of the permeable concrete and the degree of automation of manufacturing, and save the manufacturing time and the labor cost.

The technical scheme is as follows: the 3D printing permeable concrete structure comprises a mortar layer and a coarse aggregate layer which are arranged in a staggered mode, wherein the bottommost layer and the topmost layer are the mortar layer, raw materials of the mortar layer comprise 40.2-45.1 parts of cement, 40.2-45.1 parts of sand, 13.8-15.9 parts of tap water, 0.03-0.05 part of water reducer, 0.03-0.05 part of retarder and 0.04-0.06 part of hydroxypropyl methyl cellulose according to the mass part ratio, and the coarse aggregate layer is coarse aggregate with the particle size of 10-20 mm.

Preferably, the mortar layer is formed by stacking two layers of 3D printed mortar, the 3D printer nozzle is circular, the interval between each layer of adjacent printing paths is set to be the diameter of the printer nozzle, and the height of each layer of 3D printed mortar is the radius of the 3D printer nozzle.

Preferably, the cement is silicate cement or sulphoaluminate cement, and the sand is river sand or machine-made quartz sand with the particle size of 0.5-1 mm.

Preferably, the water reducer is a polycarboxylic acid high-efficiency water reducer.

Preferably, the retarder is at least one of sodium gluconate, citric acid and tartaric acid.

Preferably, the mass ratio of the sand to the cement is 1:1, and the mass ratio of the tap water to the cement is 0.35:1, the mass ratio of the water reducer to the cement is 0.001:1, the mass sum of the retarder and the hydroxypropyl methylcellulose and the mass ratio of cement are 0.002:1.

based on the preparation method of the 3D printing permeable concrete structure, the preparation method comprises the following steps:

step one, weighing cement, sand, tap water, a water reducing agent, a retarder and hydroxypropyl methyl cellulose according to a proportion;

pouring the raw materials in the first step into a mortar stirrer to stir for at least 5 minutes until the raw materials are uniformly mixed;

step three, conveying the uniformly stirred cement mortar to a 3D printer to wait for printing;

fourthly, printing the first layer of cement mortar according to the set printing parameters;

step five, printing the second layer of cement mortar, wherein printing parameters are the same as those of the first layer;

step six, uniformly scattering coarse aggregate on the second mortar layer until the coarse aggregate is completely covered;

step seven, lifting a spray head of a mortar printer upwards by 20 mm, repeating the steps four, five and six, and printing two layers of cement mortar and one layer of coarse aggregate in sequence;

step eight, repeating the step seven for a plurality of times;

step nine, lifting a spray head of a mortar printer upwards by 20 mm, repeating the steps four and five to print the two layers of cement mortar on the top layer, and finishing printing;

tenth, curing the printed component for 28 days at the constant temperature and humidity of 20+/-2 ℃ and humidity of more than 95%;

and eleventh, cutting the cured member into a regular hexahedron, and rotating the regular hexahedron by 90 degrees in the original printing and placing direction for use.

Preferably, in the second step, one half of tap water and other raw materials are poured into the container and stirred for 2 minutes, and then the rest half of tap water is poured into the container and stirred until the tap water and other raw materials are uniformly mixed.

Preferably, in the fourth step, the printing parameters are set to be extrusion speed 1 r/s and moving speed 50 mm/s.

Preferably, in the eighth step, the step is repeated seven times.

The beneficial effects are that: the invention provides an automatic manufacturing method of novel pervious concrete, which improves the water permeability and the automatic manufacturing degree of the concrete, saves the manufacturing time and the labor cost, is widely applied, and can relieve urban waterlogging and urban heat island effect which often occur in urban construction.

Drawings

FIG. 1 is a schematic diagram of raw material weighing;

FIG. 2 is a process of stirring mortar using a mortar stirrer;

FIG. 3 is an exemplary diagram of a mortar print path;

FIG. 4 is a process of printing mortar by a 3D printer;

FIG. 5 is a process of printing aggregate;

FIG. 6 is a formed pervious concrete;

FIG. 7 shows the cut pervious concrete and the direction of use, wherein (a) is the cube member cut to a side length of 80 mm and the direction of use described in example 3, and (b) is the cube member cut to a side length of 125 mm and the direction of use described in example 4;

FIG. 8 is a schematic diagram showing the steps of the method for preparing 3D printing permeable concrete structure according to the present invention;

FIG. 9 is a diagram showing a print path according to example 5;

FIG. 10 is a diagram showing the printing process according to example 5;

FIG. 11 is a diagram showing the printing process according to example 6;

FIG. 12 is a physical diagram of the printing process of comparative example 1;

FIG. 13 is a physical diagram of the printing process of comparative example 2;

fig. 14 is a real image of the printing process of comparative example 3.

The numerical references in the drawings are as follows: 1. raw materials; 2. a raw material barrel; 3. a balance; 4. a mortar mixer; 5. mortar stirring barrel; 6. stirring the well stirred mortar; 7. discharging hopper of mortar printer; 8. a mortar printing path; 9. mortar; 10. coarse aggregate; 11. coarse aggregate discharge hopper; 12. 3D printing of the cut permeable concrete (side length 80 mm); 13. rainwater; 14. the cut 3D printed pervious concrete (side 125 mm).

Detailed Description

The invention is further described below with reference to the drawings and specific embodiments.

In the embodiment of the present disclosure, the 3D printer nozzle is circular, and its diameter is 20 mm.

Example 1

The 3D printing permeable concrete structure comprises a mortar layer and a coarse aggregate layer which are arranged in a staggered mode, wherein the bottommost layer and the topmost layer are the mortar layer, raw materials of the mortar layer comprise 40.2-45.1 parts of cement, 40.2-45.1 parts of sand, 13.8-15.9 parts of tap water, 0.03-0.05 part of water reducer, 0.03-0.05 part of retarder and 0.04-0.06 part of hydroxypropyl methyl cellulose according to the mass part ratio, and the coarse aggregate layer is coarse aggregate with the particle size of 10-20 mm.

step eight, repeating the step seven for a plurality of times;

Example 2

The difference with embodiment 1 is that the mortar layer is formed by stacking two layers of 3D printed mortar, the 3D printer nozzle is circular, the interval between the printing paths is set to be the diameter of the printer nozzle, and the height of each layer of 3D printed mortar is the radius of the 3D printer nozzle.

The cement is silicate cement or sulphoaluminate cement.

The sand is river sand or machine-made quartz sand with the particle size of 0.5-1 mm.

The water reducer is a polycarboxylic acid high-efficiency water reducer.

The retarder is at least one of sodium gluconate, citric acid and tartaric acid.

The mass ratio of the sand to the cement is 1:1, and the mass ratio of the tap water to the cement is 0.35:1, the mass ratio of the water reducer to the cement is 0.001:1, the mass sum of the retarder and the hydroxypropyl methylcellulose and the mass ratio of cement are 0.002:1.

in the second step, one half of tap water and other raw materials are poured into the container and stirred for 2 minutes, and then the rest half of tap water is poured into the container and stirred until the tap water and other raw materials are uniformly mixed.

In the fourth step, the set printing parameters are extrusion speed 1 r/s and moving speed 50 mm/s.

In the eighth step, the step is repeated seven times.

Example 3

In the same way as in example 2, using balance 3 shown in fig. 1 to measure Portland cement 10 kg, river sand 10 kg with particle size of 0.5-1 mm, tap water 3.5 kg, polycarboxylic acid high-efficiency water reducer 10 g, sodium gluconate 8 g, hydroxypropyl methylcellulose 12 g, and adding into raw material barrels 2; adding one half of tap water and other raw materials 1 into a mortar stirring barrel 5, starting a mortar stirring machine 4 to stir for 2 minutes, and adding the remaining one half of water to stir for 3 minutes, wherein the stirring is shown in figure 2; delivering the stirred mortar 6 to a discharge hopper 7 of a mortar printer, and starting printing according to a mortar printing path 8 shown in fig. 3, wherein the printing path is 200 times mm long in the x direction, 11 paths in the y direction are evenly distributed, the paths in the y direction are 220 times mm long, each interval is 20 mm, and the printing range of the whole path horizontal (x-y plane) is 200 mm times 220 mm; the printing process is shown in fig. 4; after printing 2 layers of mortar 9, referring to fig. 5, uniformly spreading coarse aggregate 10 with the particle size of 10-20 mm by adopting a coarse aggregate discharge hopper 11; when the coarse aggregate 10 completely covers the mortar 9, lifting (along the z-axis direction) the mortar printer nozzle 20 mm, starting to print two layers of mortar above the coarse aggregate, and sequentially repeating to print 5 layers of coarse aggregate 10 and 12 layers of mortar 9, as shown in fig. 6; curing the printed permeable concrete member at 20+/-2 ℃ with constant temperature and humidity of more than 95% for 28 days, cutting the member into a cube member with the side length of 80 mm (3D printed permeable concrete (side length of 80 mm) 12), and finally rotating the cut member by 90 degrees around the x-axis to be used as a permeable concrete member (the permeable water source is rainwater 13 in the embodiment), as shown in fig. 7 (a); the entire flow can be referred to in fig. 8. The compressive strength of the obtained pervious concrete is 28.9 MPa, and the water permeability coefficient is 1.8 mm/s.

Example 4

In the same way as in example 2, weighing sulphoaluminate cement 15 kg, river sand 15 kg with the particle size of 0.5-1 mm, tap water 5.1 kg, polycarboxylic acid high-efficiency water reducer 15 g, tartaric acid 15 g and hydroxypropyl methylcellulose 15 g by using a balance 3 shown in fig. 1, and feeding the materials into respective raw material barrels 2; adding one half of tap water and other raw materials 1 into a mortar stirring barrel 5, starting a mortar stirring machine 4 to stir for 2 minutes, and adding the remaining one half of water to stir for 3 minutes, wherein the stirring is shown in figure 2; delivering the stirred mortar 6 to a discharge hopper 7 of a mortar printer, and starting printing according to a mortar printing path 8 shown in fig. 3, wherein the printing path is 200 times mm long in the x direction, 11 paths in the y direction are evenly distributed, the paths in the y direction are 220 times mm long, each interval is 20 mm, and the printing range of the whole path horizontal (x-y plane) is 200 mm times 220 mm; the printing process is shown in fig. 4; after printing 2 layers of mortar 9, referring to fig. 5, uniformly spreading coarse aggregate 10 with the particle size of 10-20 mm by adopting a coarse aggregate discharge hopper 11; when the coarse aggregate 10 completely covers the mortar 9, lifting (along the z-axis direction) the mortar printer nozzle 20 mm, starting to print two layers of mortar above the coarse aggregate, and sequentially repeating to print 5 layers of coarse aggregate 10 and 12 layers of mortar 9, as shown in fig. 6; finally, curing the printed permeable concrete member at a constant temperature and humidity of 20+/-2 ℃ with humidity of more than 95% for 28 days, cutting the member into a cube member with a side length of 125 mm (3D printed permeable concrete (side length of 125 mm) 14 after cutting), and finally, rotating the cut member by 90 degrees around an x-axis to be used as a permeable concrete member (the permeable water source is rainwater 13 in the embodiment), wherein the permeable concrete member is shown in fig. 7 (b); the entire flow can be referred to in fig. 8. The compressive strength of the obtained pervious concrete is 32.5 MPa, and the water permeability coefficient is 1.1 mm/s.

Example 5

In the same way as in example 3, the balance 3 shown in fig. 1 is adopted to measure raw materials, the total weight of the raw materials is 10 kg, wherein Portland cement 4.02 kg, river sand 4.51 kg with the particle size of 0.5-1 mm, tap water 1.456 kg, polycarboxylic acid high-efficiency water reducer 5 g, sodium gluconate 3 g and hydroxypropyl methyl cellulose 6 g are respectively added into the raw material barrels 2; the mortar stirring process is the same as that of example 3, the printing path is 100 mm in x direction, 6 paths in y direction are evenly distributed, the paths in y direction are 100 mm long, each interval is 20 mm, and as shown in fig. 9, the printing range of the whole path horizontal (x-y plane) is 100 mm ×100 mm; the printing process is the same as that of example 3, as shown in fig. 10; printing 3 layers of coarse aggregate and 8 layers of mortar together; curing conditions were the same as in example 3; finally, the resulting block was cut into a cube member having a side length of 50 mm, and the compressive strength was measured to be 22.7 MPa, and the water permeability coefficient was measured to be 1.5 mm/s.

Example 6

In the same way as in example 4, the balance 3 shown in fig. 1 is adopted to measure raw materials, the total weight of the raw materials is 10 kg, wherein sulfoaluminate cement is 4.51 kg, river sand with the particle size of 0.5-1 mm is 4.02 kg, tap water is 1.458 kg, polycarboxylic acid high-efficiency water reducer 3 g, tartaric acid is 5 g, and hydroxypropyl methylcellulose is 4 g, and the raw materials are respectively added into raw material barrels 2; the rest of the printing process is the same as that of example 5, and as shown in FIG. 11, the compressive strength of the pervious concrete member is measured to be 29.6 MPa, and the water permeability coefficient is measured to be 0.7 mm/s.

Comparative example 1

39 parts of silicate cement, 48 parts of river sand, 12.9 parts of tap water, 0.03 part of polycarboxylic acid high-efficiency water reducer, 0.03 part of sodium gluconate and 0.04 part of hydroxypropyl methyl cellulose are adopted in the comparative example, and the printing parameters and the printing process are the same as those in example 3, but the proportion of raw materials does not accord with the proportion protected by the patent, so that the mortar is dry and cracked, and cannot be continuously printed, as shown in fig. 12.

Comparative example 2

The materials and proportions used in this comparative example were the same as in example 3, but after the spreading of the coarse aggregate was completed, the mortar printing head was raised to a height of 30: 30 mm, and each printing path was spaced 25: 25 mm in the plane, both of which were larger than the corresponding dimensions protected by this patent, resulting in failure of the subsequent printing process, and the structure was unusable, as shown in fig. 13.

Comparative example 3

The materials and proportions used in this comparative example are the same as those in example 3, but after the coarse aggregate is spread, the lifting height of the mortar printing nozzle is 10 mm, which is less than 20 mm protected by this patent, resulting in compact printing structure and water permeability coefficient reduced to below 0.1 mm/s, as shown in fig. 14.

Claims

1. The preparation method of the 3D printing permeable concrete structure is characterized in that the 3D printing permeable concrete structure comprises a mortar layer and a coarse aggregate layer which are arranged in a staggered manner, wherein the bottommost layer and the topmost layer are the mortar layer, the mortar layer comprises 40.2-45.1 parts of cement, 40.2-45.1 parts of sand, 13.8-15.9 parts of tap water, 0.03-0.05 part of water reducer, 0.03-0.05 part of retarder and 0.04-0.06 part of hydroxypropyl methyl cellulose according to the mass part ratio, and the coarse aggregate layer is coarse aggregate with the particle size of 10-20 mm, and the preparation method of the 3D printing permeable concrete structure comprises the following steps: step one, weighing cement, sand, tap water, a water reducing agent, a retarder and hydroxypropyl methyl cellulose according to a proportion; pouring the raw materials in the first step into a mortar stirrer to stir for at least 5 minutes until the raw materials are uniformly mixed; step three, conveying the uniformly stirred cement mortar to a 3D printer to wait for printing; fourthly, printing the first layer of cement mortar according to the set printing parameters; step five, printing the second layer of cement mortar, wherein printing parameters are the same as those of the first layer; step six, uniformly scattering coarse aggregate on the second mortar layer until the coarse aggregate is completely covered; step seven, lifting a spray head of a mortar printer upwards by 20 mm, repeating the steps four, five and six, and printing two layers of cement mortar and one layer of coarse aggregate in sequence; step eight, repeating the step seven for a plurality of times; step nine, lifting a spray head of a mortar printer upwards by 20 mm, repeating the steps four and five to print the two layers of cement mortar on the top layer, and finishing printing; tenth, curing the printed component for 28 days at the constant temperature and humidity of 20+/-2 ℃ and humidity of more than 95%; and eleventh, cutting the cured member into a regular hexahedron, and rotating the regular hexahedron by 90 degrees in the original printing and placing direction for use.

2. The method for preparing the 3D printing pervious concrete structure according to claim 1, wherein the mortar layer is formed by stacking two layers of 3D printed mortar, the 3D printer nozzle is circular, the interval between each two adjacent printing paths is set to be the diameter of the printer nozzle, and the height of each layer of 3D printed mortar is the radius of the 3D printer nozzle.

3. The method for preparing the 3D printing permeable concrete structure according to claim 1, wherein the cement is silicate cement or sulphoaluminate cement, and the sand is river sand or machine-made quartz sand with the particle size of 0.5-1 mm.

4. The method for preparing a 3D printing pervious concrete structure according to claim 1, wherein the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent.

5. The method for preparing a 3D printed pervious concrete structure according to claim 1, wherein the retarder is at least one of sodium gluconate, citric acid and tartaric acid.

6. The method for preparing a 3D printing pervious concrete structure according to claim 1, wherein the mass ratio of sand to cement is 1:1, and the mass ratio of tap water to cement is 0.35:1, the mass ratio of the water reducer to the cement is 0.001:1, the mass sum of the retarder and the hydroxypropyl methylcellulose and the mass ratio of cement are 0.002:1.

7. the method for preparing a 3D printing pervious concrete structure according to claim 1, wherein in the second step, half of tap water and other raw materials are poured into the container and stirred for 2 minutes, and then the rest half of tap water is poured into the container and stirred until the tap water and the rest half of tap water are uniformly mixed.

8. The method for preparing a 3D printing pervious concrete structure according to claim 1, wherein in the fourth step, the set printing parameters are extrusion speed 1 r/s and moving speed 50 mm/s.

9. The method for preparing a 3D printed pervious concrete structure according to claim 1, wherein in the step eight, the step is repeated seven times.