3D printing lightweight concrete prepared from modified waste ceramic powder and preparation method thereof

Abstract

This invention relates to the field of building materials technology, and particularly to a 3D-printed lightweight concrete prepared from modified waste ceramic powder and its preparation method. The 3D-printed lightweight concrete comprises the following components: cement, mineral admixtures, ceramic powder, manufactured sand, fiber, other additives, and water; the ceramic powder is modified waste ceramic powder; or, the ceramic powder is a mixture of modified waste ceramic powder and unmodified ceramic powder; the unmodified ceramic powder has a specific surface area of ​​230–450 m². 2 The first ceramic powder is 1 kg; the modified waste ceramic powder is obtained by ball milling mixture M with an activator; wherein, mixture M is obtained by heating, stirring, and drying the second ceramic powder and the modifier solution. This invention applies the resource utilization of waste ceramics to 3D printed lightweight concrete, saving costs and resources, protecting the environment, and ensuring that the provided 3D printed lightweight concrete has good fluidity, extrudability, constructability, and durability.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building materials, in particular to a 3D printing lightweight concrete prepared from modified waste ceramic powder and a preparation method thereof. BACKGROUND

[0002] 3D printing concrete technology is a new technology developed on the basis of 3D printing technology, and its basic principle is to use a computer to produce three-dimensional information through 3D modeling and segmentation of concrete components, then to extrude the prepared concrete mixture through an extrusion device, and to stack layer by layer through a nozzle according to the set program, and finally to obtain a concrete component.

[0003] With the progress of world industrialization, the production and consumption of glass ceramics are increasing year by year. About 5 million tons of waste ceramics are generated in China every year, accounting for 4% of municipal solid waste, which has a huge impact on the living environment of human beings. With the increase of these waste ceramics, recycling of these waste ceramics has become an important problem in urban management. However, due to the size, pollution, color and other reasons, these waste ceramics cannot be recycled to produce new products, and various colored glass fragments have little recycling potential. A large amount of waste ceramics has become a prominent problem of occupying valuable land resources and affecting the ecological environment.

[0004] Therefore, through the 3D printing concrete technology, the waste ceramic waste can be recycled and utilized, which can not only create considerable economic benefits, but also effectively reduce the damage and pollution of the waste ceramic waste to the environment. However, if the waste ceramic powder is directly mixed into the 3D printing concrete system as a raw material, there are performance defects such as poor construction performance and insufficient compressive strength of the prepared 3D printing concrete. Therefore, how to apply waste ceramics to 3D printing concrete and ensure that the prepared 3D printing concrete has good compressive strength, fluidity, extrudability and construction performance and other performance requirements is an urgent technical problem to be solved today. SUMMARY

[0005] To solve the problems mentioned in the background, the present application provides a 3D printing lightweight concrete prepared from modified waste ceramic powder, and the technical scheme is as follows:

[0006] The 3D printing lightweight concrete prepared from modified waste ceramic powder comprises the following components: cement, mineral admixture, ceramic powder, machine-made sand, fiber, other additives and water; the ceramic powder is modified waste ceramic powder; or, the ceramic powder is a mixture of modified waste ceramic powder and unmodified ceramic powder; the unmodified ceramic powder has a specific surface area of 230-450 m 2 / kg; the modified waste ceramic powder is prepared by adding the active agent to the mixture M by ball milling, so that the specific surface area of the modified waste ceramic powder is >960m 2 / kg; wherein the mixture M is prepared by heating and stirring the second ceramic powder and the modifier solution, and then drying.

[0007] In an embodiment, the modifier is a mixture of methacrylic acid and methyl silicone oil, and the mass ratio of the methacrylic acid to the methyl silicone oil is (1.0-1.5):(0.5-0.8); the active agent is a mixture of sodium silicate and sodium dodecyl sulfonate, and the mass ratio of the sodium silicate to the sodium dodecyl sulfonate is (0.5-1.0):(0.3-0.5).

[0008] In an embodiment, the mass ratio of the second ceramic powder to the modifier solution is 1:(10-16); the solute mass percentage concentration of the modifier solution is 0.5%-1.5%; and the mass ratio of the active agent to the mixture M is 1:(1000-1200).

[0009] In an embodiment, the preparation process of the modified waste ceramic powder is as follows: the second ceramic powder and the modifier solution are mixed and stirred at 40-60°C for 12-24h, and finally dried to form the mixture M; the active agent is added to the mixture M, and ball milling is performed for 3-8h to obtain the modified ceramic powder with a specific surface area >960m 2 / kg.

[0010] In an embodiment, the ceramic powder material is a mixture of the modified waste ceramic powder and the unmodified ceramic powder in a mass ratio of 1:(0.8-1.5).

[0011] In an embodiment, the specific surface area of the modified ceramic powder is >960m 2 / kg, and the density thereof is <2.25g / cm 3 , and the activity index thereof is >70% (the activity index refers to the compressive strength ratio, which is related to the compressive strength, and is generally tested and defined according to the fly ash activity index standard).

[0012] In an embodiment, the other additives include defoaming agents, setting accelerators, water reducing agents, and thickening agents; and the other additives include the following components in parts by weight: cement 80-200 parts, mineral admixtures 60-100 parts, ceramic powder material 60-120 parts, machine-made sand 300-500 parts, fibers 2.0-10.0 parts, defoaming agents 1.0-7.0 parts, setting accelerators 2.0-6.0 parts, water reducing agents 3.0-11.0 parts, thickening agents 2.0-12 parts, and water 70-126 parts.

[0013] In an embodiment, the cement 90-190 parts by weight, mineral admixtures 60-90 parts by weight, modified waste ceramic powder 70-110 parts by weight, machine-made sand 320-480 parts by weight, fiber 3.2-8.6 parts by weight, defoaming agent 2.4-6.4 parts by weight, accelerator 3.2-5.4 parts by weight, water reducing agent 5.6-9.2 parts by weight, thickening agent 3.2-11.4 parts by weight, and water 90-120 parts by weight are included.

[0014] In an embodiment, the cement includes one or a combination of P·O42.5 cement, P·O42.5R cement, PC 42.5 composite Portland cement, SAC42.5 sulphoaluminate cement, magnesium phosphate cement; the mineral admixtures include one or a combination of fly ash, slag powder, steel slag powder, stone powder; the fiber includes one or a combination of polypropylene fiber, basalt fiber, plant fiber.

[0015] In an embodiment, the defoaming agent includes one or a combination of chloroethane, toluene, polysiloxane polyether, polymeric propylene oxide; the accelerator includes one or a combination of sodium carbonate, lime, sodium silicate; the water reducing agent is a polycarboxylic acid water reducing agent with a water reducing rate of ≥30%; the thickening agent includes at least one of inorganic thickening agent, lignocellulose thickening agent, ether thickening agent, polyacrylate thickening agent.

[0016] The application also provides a preparation method of the 3D printing concrete prepared from the modified waste ceramic powder, which comprises the following preparation steps:

[0017] The cement, mineral admixtures, ceramic powder, fiber and machine-made sand are weighed, and the cement, mineral admixtures, modified waste ceramic powder, fiber and machine-made sand are uniformly mixed to obtain a first mixture;

[0018] Water is added to the first mixture and uniformly mixed to obtain a second mixture;

[0019] The accelerator, defoaming agent, water reducing agent and thickening agent are added to the second mixture and uniformly mixed to obtain the 3D printing concrete prepared from the modified waste ceramic powder.

[0020] Compared with the prior art, the application has the following technical effects:

[0021] The application utilizes the waste ceramic powder to prepare the 3D printing concrete, combines the waste ceramic resource utilization with the 3D printing intelligent construction, reduces the cost of the 3D printing concrete on one hand, and reuses the waste, saves resources and protects the environment on the other hand; and the application of the waste ceramic powder to the 3D printing concrete can also improve the compressive performance of the concrete, and guarantee that the 3D printing concrete has good fluidity, extrudability, constructability and durability. DETAILED DESCRIPTION

[0022] In order to make the objects, technical solutions and advantages of the embodiments of the present application clearer, the following will be clearly and completely described with the technical solutions in the embodiments of the present application. Obviously, the described embodiments are some but not all of the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by a person of ordinary skill in the art without creative work fall within the protection scope of the present application.

[0023] The present application provides a preparation method of 3D printing lightweight concrete prepared from modified waste ceramic powder, which comprises the following preparation steps:

[0024] (1) weigh cement, mineral admixture, ceramic powder and fiber, and mix the cement, mineral admixture, ceramic powder, fiber and machine-made sand uniformly to obtain a first mixture;

[0025] (2) add water to the first mixture and mix uniformly to obtain a second mixture;

[0026] (3) add a quick-setting agent, a defoaming agent, a water reducing agent and a thickening agent to the second mixture, and mix uniformly to obtain the 3D printing concrete prepared from modified waste ceramic powder.

[0027] Wherein, the mixing of each mixture is carried out by stirring, the stirring time is 2-6 min, and the stirring speed is 500-1000 rpm.

[0028] Wherein, the concrete formula is:

[0029] By weight fraction, the components include: cement 80-200 parts, mineral admixture 60-100 parts, ceramic powder 60-120 parts, machine-made sand 300-500 parts, fiber 2.0-10.0 parts, defoaming agent 1.0-7.0 parts, quick-setting agent 2.0-6.0 parts, water reducing agent 3.0-11.0 parts, thickening agent 2.0-12 parts, and water 70-126 parts.

[0030] For raw material selection

[0031] The ceramic powder is modified waste ceramic powder; or preferably, the ceramic powder is a mixture formed by mixing 1:

[0032] (0.8-1.5) by mass ratio;

[0033] Wherein, the unmodified ceramic powder is a first ceramic powder with a specific surface area of 230-450 m 2 / kg;

[0034] The modified waste ceramic powder is self-made, and the application further provides a preferred embodiment of a preparation method of the modified ceramic powder, and the specific steps are as follows:

[0035] 1) the second ceramic powder is mixed with a modifier solution at 40-60 DEG C and stirred for 12-24 hours, and finally dried to form the mixture M;

[0036] 2) the active agent is added to the mixture M, and after ball milling for 3-8 hours, the active agent is added to the mixture M, and after ball milling for 3-8 hours, the modified ceramic powder with a specific surface area of >960 m 2 / kg, a density of <2.25 g / cm 3 , and an activity of >70% is prepared.

[0037] The modifier is a mixture of methacrylic acid and methyl silicone oil, the mass ratio of the methacrylic acid to the methyl silicone oil is (1.0-1.5):(0.5-0.8); the active agent is a mixture of sodium silicate and sodium dodecyl sulfonate, the mass ratio of the sodium silicate to the sodium dodecyl sulfonate is (0.5-1.0):(0.3-0.5). The mass ratio of the second ceramic powder to the modifier solution is 1:(10-16); the solute mass percentage concentration of the modifier solution is 0.5%-1.5%; the mass ratio of the active agent to the mixture M is 1:(1000-1200).

[0038] The application further provides the following examples and comparative examples:

[0039] The application further provides the formulations (unit: weight parts) of the examples and comparative examples shown in Tables 1-2:

[0040] Table 1

[0041]

[0042]

[0043] Table 2

[0044]

[0045]

[0046] The preparation process of the specific examples and comparative examples is as follows:

[0047] Example 1

[0048] The formulation of the 3D printing concrete is as follows:

[0049] By weight parts, including the following components: cement 135 parts; mineral admixtures 80 parts; modified ceramic powder: 75 parts; machine-made sand: 400 parts; fiber: 6.0 parts; defoaming agent 4.0 parts; accelerator: 4.0 parts; water reducing agent: 7.0 parts, thickening agent 7.0 parts; water 98 parts.

[0050] Wherein, the cement used is P·O42.5R ordinary Portland cement and SAC42.5 sulphoaluminate cement mixture (mass ratio is 2:5). The mineral admixture used is stone powder. The water reducing agent used is polycarboxylic acid water reducing agent, and the water reducing rate is 35%. The fiber used is polypropylene fiber, and the fiber length is 6-9 mm. The accelerator used is a mixture of sodium carbonate, lime and sodium silicate in a mass ratio of 1:1:0.5. The thickening agent is a lignocellulosic thickening agent, and the defoaming agent is a polysiloxane polyether defoaming agent.

[0051] The preparation process of the modified waste ceramic powder is as follows:

[0052] The waste ceramic is first washed, dried and broken, then mixed with the modifier solution at 40℃ for 24h, and finally dried to form the mixture M; the active agent is added to the mixture M, and the modified ceramic powder is prepared after ball milling for 8h, the specific surface area of the modified ceramic powder is >960m 2 / kg, and its density is <2.25g / cm 3 , and the activity is >70%.

[0053] Wherein, the mass ratio of waste ceramic to the modifier solution is 1:12, and the mass percentage concentration of the modifier solution is 1.2%; the mass ratio of the active agent to the mixture M is 1:1000. The active agent is a mixture of sodium silicate and sodium dodecyl sulfonate, and the mass ratio of the two is 0.7:0.4. The modifier is a mixture of methacrylic acid and methyl silicone oil, and the mass ratio of the two is 1.2:0.6.

[0054] The preparation process of the 3D printing concrete is as follows:

[0055] The cement, mineral admixtures, modified ceramic powder, fiber and machine-made sand in the above proportions are stirred uniformly for 1min at a stirring rate of 500rpm to obtain a first mixture;

[0056] 98 parts of water are added to the first mixture, and stirred uniformly for 2min at a stirring rate of 800rpm to obtain a second mixture;

[0057] The accelerator, defoaming agent, water reducing agent and thickening agent are added to the second mixture and stirred uniformly for 2min at a stirring rate of 500rpm to finally prepare the 3D printing concrete.

[0058] Example 2

[0059] The formula of the 3D printing concrete is:

[0060] The following components are included by weight parts: cement 120 parts; mineral admixture 80 parts; ceramic powder (all modified ceramic powder): 90 parts; machine-made sand: 400 parts; fiber: 6.0 parts; defoaming agent 4.0 parts; accelerator: 4.0 parts; water reducing agent: 7.0 parts, thickening agent 7.0 parts; water 98 parts.

[0061] The cement used is a mixture of P·O42.5R ordinary portland cement and SAC42.5 sulphoaluminate cement (mass ratio 2:5). The mineral admixture used is stone powder. The water reducing agent used is a polycarboxylic acid water reducing agent with a water reducing rate of 35%. The fiber used is polypropylene fiber with a fiber length of 6-9 mm. The accelerator used is a mixture of sodium carbonate, lime and sodium silicate in a mass ratio of 1:1:0.5. The thickening agent is a lignocellulosic thickening agent, and the defoaming agent is a polysiloxane polyether defoaming agent.

[0062] The preparation process of the modified ceramic powder is:

[0063] The waste ceramic is first washed, dried and broken, then mixed and stirred with a modifier solution at 40℃ for 12h, and finally dried to form the mixture M; the active agent is added to the mixture M, and the modified ceramic powder is prepared after ball milling for 3h, the specific surface area of the modified ceramic powder is >960m 2 / kg, and its density is <2.25g / cm 3 , and the activity is >70%.

[0064] The mass ratio of the waste ceramic to the modifier solution is 1:12, and the mass percentage concentration of the modifier solution is 1.2%; the mass ratio of the active agent to the mixture M is 1:1000. The active agent is a mixture of sodium silicate and sodium dodecyl sulfonate in a mass ratio of 0.7:0.4. The modifier is a mixture of methacrylic acid and methyl silicone oil in a mass ratio of 1.2:0.6.

[0065] The preparation process of the 3D printing concrete is:

[0066] The cement, mineral admixture, modified ceramic powder, fiber and machine-made sand in the above proportions are stirred uniformly for 1min at a stirring rate of 500rpm to obtain a first mixture;

[0067] 98 parts of water are added to the first mixture, and stirred uniformly for 2min at a stirring rate of 800rpm to obtain a second mixture;

[0068] The second mixture is added with a rapid setting agent, a defoaming agent, a water reducing agent and a thickening agent, and stirred for 2 min at a stirring rate of 500 rpm, to obtain the 3D printing concrete.

[0069] Example 3

[0070] The ceramic powder added according to the formulation in Table 1 is a mixture of modified waste ceramic powder and unmodified ceramic powder with a specific surface area of 230 m 2 / kg in a ratio of 1:1.

[0071] The difference between it and Example 1 is only that the formulation ratio and the added ceramic powder are different, and the selection of other raw materials, the preparation process of modified waste ceramic and the preparation process of concrete are consistent with Example 1.

[0072] Example 4

[0073] The ceramic powder added according to the formulation in Table 1 is a mixture of modified waste ceramic powder and unmodified ceramic powder with a specific surface area of 450 m 2 / kg in a ratio of 1:1.

[0074] The difference between it and Example 1 is only that the formulation ratio and the added ceramic powder are different, and the selection of other raw materials, the preparation process of modified waste ceramic and the preparation process of concrete are consistent with Example 1.

[0075] Example 5

[0076] The ceramic powder added according to the formulation in Table 1 is a modified ceramic powder, and the modification temperature is 50℃.

[0077] The difference between it and Example 1 is only that the formulation ratio and the modification temperature are different, and the selection of other raw materials, the preparation process of modified waste ceramic and the preparation process of concrete are consistent with Example 1.

[0078] Example 6 The ceramic powder added according to the formulation in Table 1 is a modified ceramic powder, and the modification temperature is 60℃.

[0079] The difference between it and Example 1 is only that the formulation ratio and the modification temperature are different, and the selection of other raw materials, the preparation process of modified waste ceramic and the preparation process of concrete are consistent with Example 1.

[0080] Comparative Example 1 (all the added ceramic powder is not modified)

[0081] Strictly according to Example 1, the unmodified ceramic powder (i.e. ceramic powder) is added in the preparation of 3D printing concrete, and is used for performance comparison research with the 3D printing concrete of the application.

[0082] The difference between this comparative example and Example 1 is that the modified ceramic powder is not added, and other formulations and preparation processes are consistent with Example 2.

[0083] Comparative Example 2 (no modified ceramic powder is added)

[0084] Strictly in accordance with Example 1, no modified ceramic powder is added in the preparation of 3D printing concrete, and is used for performance comparison research with the 3D printing concrete of the application.

[0085] The difference between this comparative example and Example 1 is that the modified ceramic powder is not added, and other formulations and preparation processes are consistent with Example 1.

[0086] Comparative Example 3 (the modifier is replaced by a silane coupling agent)

[0087] The difference between this comparative example and Example 1 is that the modifier is replaced by a silane coupling agent, and other formulations and preparation processes are consistent with Example 1.

[0088] Comparative Example 4 (the active agent is replaced by triethanolamine)

[0089] The difference between this comparative example and Example 1 is that the active agent is replaced by triethanolamine, and other formulations and preparation processes are consistent with Example 1.

[0090] Comparative Example 5 (the modified ceramic powder is replaced by a modified ceramic powder with a specific surface area less than 960 m 2 / kg)

[0091] The difference between this comparative example and Example 1 is that the modified ceramic powder is replaced by a modified ceramic powder with a specific surface area less than 960 m 2 / kg, and other formulations and preparation processes are consistent with Example 1.

[0092] Comparative Example 6 (the unmodified ceramic powder is replaced by an unmodified ceramic powder with a specific surface area of 960 m 2 / kg, and the specific surface area of the unmodified ceramic powder is too large)

[0093] The difference between this comparative example and Examples 3-4 is that the unmodified ceramic powder with a small specific surface area is replaced by an unmodified ceramic powder with a specific surface area of 960 m 2 / kg, and other formulations and preparation processes are consistent with Examples 3-4.

[0094] Comparative Example 7 (the modified ceramic powder with a specific surface area greater than 960 m 2 / kg is replaced by a modified ceramic powder with a specific surface area less than 960 m 2 / kg, and the specific surface area of the modified ceramic powder is too small)

[0095] The difference between this comparative example and Example 4 is that the modified ceramic powder with a specific surface area greater than 960 m 2 / kg of modified ceramic powder with a specific surface area less than 960 m 2 / kg of modified ceramic powder (about 450 m 2 / kg), other formulations and preparation processes are consistent with Example 4.

[0096] Among them, different specific surface area modified ceramic powders can be obtained by adjusting process parameters such as ball milling.

[0097] Comparative Example 8 (modified temperature replaced from 40℃ to 80℃)

[0098] The difference between Examples 5-6 is only that the modified temperature is replaced by 80℃, and other formulations and preparation processes are consistent with Examples 5-6.

[0099] For the above examples and comparative examples, performance tests are carried out according to the standard "Concrete 3D Printing Technology Regulations" T / CECS 786-2020, and the test results are shown in Tables 3-4:

[0100] Table 3

[0101]

[0102] Table 4

[0103]

[0104]

[0105] Note: The modified ceramic powder content is the percentage of ceramic powder in the cementitious material; the 3d indicates the compressive strength of the concrete after 3 days.

[0106] The evaluation method and way of the extrudability of good, good and poor levels are: the extruded slurry strip can be continuously extruded within 1 minute, and is evaluated as good, the extrusion process is interrupted 1-2 times and is evaluated as good, and the extrusion process appears more than 2 times interruption and blockage and is evaluated as poor.

[0107] The evaluation method and way of the buildability of good, good and poor levels are: the printed strip expands and deforms in the horizontal direction during the process of layer-by-layer stacking, and the size of the expansion and deformation is ≤10mm, which is evaluated as good, the size of the expansion and deformation is 10-20mm, which is evaluated as good, and the size of the expansion and deformation is >20mm, which is evaluated as poor.

[0108] From the analysis of the test results in Tables 3-4, it can be seen that:

[0109] (1) Examples 1-2 (ceramic powder is all modified ceramic powder):

[0110] In Examples 1-2 of the present application, modified ceramic powder is added, the compressive strength of the 3D printing concrete prepared is improved, and the 3D printing concrete has good fluidity, extrudability, buildability and good comprehensive performance.

[0111] As can be seen from the data of Comparative Examples 1-2, with the increase of the amount of modified ceramic powder, the flowability of the 3D printing concrete decreases, and the extrudability slightly decreases, which may be because the particle size of the waste ceramic is small after grinding, and the water absorption is strong. If the content is too high, it may cause the 3D printing concrete to be thick and dry, which is not conducive to extrusion from the nozzle of the printer, thereby reducing the buildability and extrudability. Controlling the amount of modified ceramic powder within the range defined in the application can fully apply waste ceramic to 3D printing concrete while ensuring that the 3D printing concrete still has good flowability, extrudability, buildability, and good comprehensive performance, which can meet the use requirements.

[0112] (2) Examples 3-4 (ceramic powder is composed of modified ceramic powder and unmodified ceramic powder)

[0113] As can be seen from the data of Examples 3-4:

[0114] In Comparative Examples 1-2 and Examples 3-4, the ceramic powder and modified ceramic powder are added in a lower amount, and the extrudability and buildability are still good, and the compressive strength and flowability parameters show that the prepared 3D concrete meets the corresponding application requirements. This may be because the unmodified ceramic powder can replace part of the modified ceramic powder, improve the water absorption, and enhance the buildability of the concrete to a certain extent. Compared with the scheme of using all modified ceramic powder, this scheme can reduce the manufacturing cost while meeting the comprehensive performance requirements of good flowability, extrudability and buildability.

[0115] (3) Examples 5-6 (increased modification temperature)

[0116] As can be seen from the test results of Examples 1 and Comparative Examples 5-6, Examples 5-6 still have extrudability, buildability and compressive strength comparable to Examples 1-2 with a lower amount of modified ceramic, which shows that the activity of the modified ceramic powder is enhanced with the increase of the modification temperature.

[0117] (4) Comparative Example 1

[0118] As can be seen from the test results of Examples and Comparative Example 1, the buildability of Comparative Example 1 is significantly worse than that of Examples, and the compressive strength is significantly reduced. The modified waste ceramic powder used in the examples of the application has higher activity than the untreated waste ceramic powder. Replacing the modified ceramic powder in an equal amount can improve the compressive strength and buildability of the 3D printing concrete.

[0119] This may be because: the modified ceramic powder has a certain activity, can replace part of the cement, and can promote the generation of cement hydration products; on the other hand, the modified ceramic powder that does not participate in hydration fills the internal voids of 3D printed concrete, making its internal structure more compact, thereby improving the compressive strength of 3D printed concrete.

[0120] (5) Comparative Example 2

[0121] The difference between this comparative example and Example 1 is only that this comparative example does not add modified ceramic powder. From the test results of Example and Comparative Example 2, it can be seen that compared with Comparative Example 2 (poor constructability) without adding modified ceramic powder, the constructability is significantly improved after adding modified ceramic powder in the example. This may be because a part of the modified ceramic powder promotes the progress of the cement hydration reaction, so that more hydration products such as C-S-H gel and ettringite are generated in the hardened body.

[0122] The 3D printed concrete prepared from the modified waste ceramic powder and the preparation method thereof provided by the application at least include the following design concepts, action mechanisms and beneficial effects:

[0123] (1) The application modifies the ceramic powder by surface modification treatment of the waste ceramic powder with a modifier. The solute in the modifier is adsorbed on the surface of the waste ceramic powder, so that an organic molecular layer (Si-O, Si-O-Si, C-O, etc. Organic functional groups) is formed, and the hydrophilicity is enhanced. In the cement matrix, hydrolysis reaction is carried out with water to form Si-OH, OH groups are formed on the surface, and further chemical combination of cement paste is carried out through hydrogen bond combination or dehydration condensation, so as to improve the performance.

[0124] (2) The application selects a specific modifier (a mixture of methacrylic acid and methyl silicone oil) and a specific activator (a mixture of sodium silicate and sodium dodecyl sulfonate) to treat the waste ceramic powder. Compared with the conventional modifiers and activators such as silane coupling agent and triethanolamine, the modified ceramic powder obtained by modification has better effect when incorporated into the preparation of 3D concrete.

[0125] (3) The application also strictly controls the modification temperature during the treatment of the waste ceramic powder with the specific modifier and active agent, so as to ensure that the modified ceramic powder has good activity. If the modification temperature is lower than the range defined in the application, the activity of the modified ceramic powder will be insufficient, and the properties such as buildability and compressive strength of the 3D printing concrete prepared will be poor. If the modification temperature is higher than the range defined in the application, the modified ceramic powder will agglomerate, and the activity will be invalid, and the properties such as buildability and compressive strength of the 3D printing concrete prepared will be poor.(3) The specific surface area of the modified ceramic powder during the treatment of the waste ceramic powder with the specific modifier and active agent is strictly controlled, so as to ensure that the modified ceramic powder has good activity, so that the 3D printing concrete prepared has good fluidity, buildability and compressive strength and other properties. If the specific surface area of the modified ceramic powder is lower than the range defined in the application, the activity of the modified ceramic powder will decrease, and the properties such as compressive strength and buildability of the 3D printing concrete prepared will be poor.

[0126] (4) The application incorporates mineral admixtures, which can also replace part of the cement, to play the role of cementitious materials in the 3D printing concrete. On the other hand, such design can reduce the overall material cost.

[0127] (5) The application incorporates fibers, accelerators, thickening agents, and polycarboxylic acid water reducing agent components to work together with other components. The fibers (such as polypropylene fibers, etc.) can improve the crack resistance of the 3D printing concrete; the accelerator can adjust the setting time of the 3D printing concrete; the thickening agent can improve the bonding performance of the 3D printing concrete; the polycarboxylic acid water reducing agent can reduce the water consumption of the thermal insulation mortar and improve the fluidity and compressive strength of the 3D printing concrete. Through the combination of these components, the 3D printing concrete has excellent extrudability and buildability.

[0128] In summary, the application recycles waste ceramic materials, and the waste ceramic powder is modified and then incorporated into concrete. The modified ceramic powder cooperates with other components to make the concrete reach the required performance. The application combines the resource utilization of waste ceramic with 3D printing intelligent construction, which reduces the cost of 3D printing concrete, recycles waste materials, saves resources, and protects the environment. In addition, the application of waste ceramic in 3D printing concrete can also improve the compressive performance of the concrete, ensuring that the 3D printing concrete has good fluidity, extrudability, buildability, and durability. The application is conducive to the development of 3D printing concrete technology and has high environmental and social benefits.

[0129] It should be noted that:

[0130] For the proportion of raw material components:

[0131] In addition to the actual choices embodied in the above specific embodiments, the formula proportions of the components of the 3D-printed lightweight concrete can be feasible within the above formula limits, including but not limited to the actual choices embodied in the above embodiments.

[0132] For raw material component selection:

[0133] The ceramic powder includes but is not limited to recycled waste ceramic powder. Before modification, the waste ceramic can be preferably washed, dried, and crushed.

[0134] In addition to the actual choices embodied in the above specific embodiments, preferably, the cement is selected from one or a combination of P·O42.5 cement, P·O42.5R cement, PC 42.5 composite portland cement, SAC42.5 sulphoaluminate cement, and magnesium phosphate cement, including but not limited to the actual choices embodied in the above embodiments.

[0135] In addition to the actual choices embodied in the above specific embodiments, preferably, the mineral admixture is selected from one or a combination of fly ash, slag powder, steel slag powder, and stone powder, including but not limited to the actual choices embodied in the above embodiments.

[0136] In addition to the actual choices embodied in the above specific embodiments, preferably, the fiber is selected from one or a combination of polypropylene fiber, basalt fiber, and plant fiber, including but not limited to the actual choices embodied in the above embodiments.

[0137] In addition to the actual choices embodied in the above specific embodiments, preferably, the defoaming agent is selected from one or a combination of chloroethane, toluene, polysiloxane polyether, and polymeric propylene oxide, including but not limited to the actual choices embodied in the above embodiments.

[0138] In addition to the actual choices embodied in the above specific embodiments, preferably, the accelerator is selected from one or a combination of sodium carbonate, lime, and sodium silicate, including but not limited to the actual choices embodied in the above embodiments.

[0139] In addition to the actual choices embodied in the above specific embodiments, preferably, the water-reducing agent is selected from a polycarboxylic acid water-reducing agent with a water-reducing rate ≥ 30%, including but not limited to the actual choices embodied in the above embodiments.

[0140] In addition to the actual choices embodied in the above specific embodiments, preferably, the thickening agent is selected from at least one of inorganic thickening agents, lignocellulose-based thickening agents, ether-based thickening agents, and polyacrylate thickening agents, including but not limited to the actual choices embodied in the above embodiments.

[0141] In summary, the specific parameters or some commonly used reagents or raw materials in the above embodiments are specific embodiments or preferred embodiments under the concept of the present application, but not a limitation; those skilled in the art can make adaptive adjustment within the concept and protection scope of the present application.

[0142] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, but not a limitation; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement for part or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present application.

Claims

1. A 3D printed lightweight concrete prepared with modified waste ceramic powder, characterized in that, The 3D printing lightweight concrete prepared from modified waste ceramic powder comprises the following components in parts by weight: cement 80-200 parts, mineral admixture 60-100 parts, ceramic powder 60-120 parts, machine-made sand 300-500 parts, fiber 2.0-10.0 parts, defoaming agent 1.0-7.0 parts, accelerator 2.0-6.0 parts, water reducing agent 3.0-11.0 parts, thickening agent 2.0-12 parts, and water 70-126 parts. The ceramic powder is modified waste ceramic powder; or the ceramic powder is a mixture of modified waste ceramic powder and unmodified ceramic powder. The unmodified ceramic powder is a first ceramic powder having a specific surface area of 230 to 450 m 2 / kg. The preparation process of the modified waste ceramic powder is as follows: the second ceramic powder is mixed with a modifier solution at 40-60 DEG C and stirred for 12-24 hours, and finally dried to form the mixture M; the active agent is added to the mixture M, and ball-milled for 3-8 hours to obtain the modified ceramic powder with a specific surface area of >960 m 2 / kg. The modifier is a mixture of methacrylic acid and methyl silicone oil, the mass ratio of the methacrylic acid to the methyl silicone oil being (1.0-1.5):(0.5-0.8); and the active agent is a mixture of sodium silicate and sodium dodecyl sulfonate, the mass ratio of the sodium silicate to the sodium dodecyl sulfonate being (0.5-1.0):(0.3-0.5).

2. The 3D printing lightweight concrete prepared from modified waste ceramic powder according to claim 1, characterized in that: The mass ratio of the second ceramic powder to the modifier solution is 1:(10-16); and the solute mass percentage concentration of the modifier solution is 0.5%-1.5%. The mass ratio of the active agent to the mixture M is 1:(1000-1200).

3. 3D-printed lightweight concrete prepared with modified waste ceramic powder according to any one of claims 1-2, characterized in that: The ceramic powder is a mixture of modified waste ceramic powder and unmodified ceramic powder in a mass ratio of 1:(0.8-1.5).

4. The 3D printed lightweight concrete prepared with modified waste ceramic powder as claimed in claim 1, wherein: The specific surface area of the modified ceramic powder is > 960 m 2 / g, and its density is < 2.25 g / cm 3 , and the activity index is > 70%.

5. The 3D printed lightweight concrete prepared with modified waste ceramic powder as claimed in claim 1, wherein: The other additives include defoaming agent, accelerator, water reducing agent, and thickening agent. The 3D printing lightweight concrete prepared from modified waste ceramic powder comprises the following components in parts by weight: cement 80-200 parts, mineral admixture 60-100 parts, ceramic powder 60-120 parts, machine-made sand 300-500 parts, fiber 2.0-10.0 parts, defoaming agent 1.0-7.0 parts, accelerator 2.0-6.0 parts, water reducing agent 3.0-11.0 parts, thickening agent 2.0-12 parts, and water 70-126 parts.

6. The 3D printing lightweight concrete prepared from modified waste ceramic powder according to claim 5, characterized in that: The cement comprises one or a combination of P·O42.5 cement, P·O42.5R cement, PC 42.5 composite portland cement, SAC42.5 sulphoaluminate cement, and magnesium phosphate cement; The mineral admixture comprises one or a combination of fly ash, slag powder, steel slag powder, and stone powder; The fiber comprises one or a combination of polypropylene fiber, basalt fiber, and plant fiber.

7. The 3D printed lightweight concrete prepared with modified waste ceramic powder as claimed in claim 5, wherein: The defoaming agent comprises one or a combination of chloroethane, toluene, polysiloxane polyether, and polymeric propylene oxide; The accelerator comprises one or a combination of sodium carbonate, lime, and sodium silicate; The water reducing agent is polycarboxylic acid water reducing agent, and the water reducing rate thereof is ≥30%; The thickening agent comprises at least one of inorganic thickening agent, lignocellulose thickening agent, ether thickening agent, and polyacrylate thickening agent.

8. A method for the preparation of 3D printed concrete with modified waste ceramic powder according to any one of claims 5-7, characterized in that, The 3D printing lightweight concrete prepared from modified waste ceramic powder comprises the following preparation steps: The cement, mineral admixture, ceramic powder, fiber, and machine-made sand are weighed and mixed uniformly to obtain a first mixture; Water is added to the first mixture and mixed uniformly to obtain a second mixture; The accelerator, defoaming agent, water reducing agent, and thickening agent are added to the second mixture and mixed uniformly to obtain the 3D printing lightweight concrete prepared from modified waste ceramic powder.

Images