A low-carbon bio-based recycled concrete and its preparation and application in preparing 3D printed components

Abstract

The present application relates to the technical field of building 3D printing concrete, and particularly relates to a low-carbon bio-based recycled concrete, preparation thereof and application thereof in preparation of 3D printing components. The low-carbon bio-based recycled concrete comprises cement: 100 parts; rice husk ash: 10-30 parts; diatomite: 5-15 parts; lignocellulose: 0.01-1.0 parts; steel fiber: 1-3 parts; recycled coarse aggregate: 100-250 parts; recycled fine aggregate: 100-200 parts; water reducing agent: 1-10 parts; retarder: 0.1-2.0 parts; and water: 30-60 parts. The low-carbon bio-based recycled concrete can effectively improve the rheological property, strength and durability of concrete, and improve the crack resistance of concrete while promoting the green transformation of the concrete industry. When the low-carbon bio-based recycled concrete is further applied to preparation of 3D printing components, the quality and reliability of the 3D printing components can be significantly improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of building 3D printing concrete, in particular to a low-carbon bio-based recycled concrete and its preparation and application in preparing 3D printing components. BACKGROUND

[0002] With the rapid development of urbanization, a large amount of construction waste is generated; however, the traditional landfill method not only has high economic cost and wastes land resources, but also causes environmental pollution. At the same time, with the rapid development of economy, the demand for cement is also increasing, which has caused the problems of carbon emission and environmental pollution to be increasingly serious.

[0003] 3D printing technology has attracted widespread attention in the construction industry due to its automatic construction technology without mold. However, the existing 3D printing technology causes certain pollution to the environment due to the large amount of cementitious materials used. The development of 3D printing concrete technology can alleviate the industry pressure caused by the increasingly severe labor shortage and promote the transformation process of "intelligent construction".

[0004] The strength and toughness of the existing concrete materials used in 3D printing often cannot meet the actual engineering needs, and further improvement is needed. Therefore, it is crucial to provide a concrete that promotes the recycling of solid waste resources, alleviates the pressure of the increasingly scarce natural aggregate, solves the problems of solid waste accumulation treatment, reduces carbon emissions in the production and preparation process, and has excellent performance. SUMMARY

[0005] To solve the above problems, the purpose of the present application is to provide a low-carbon bio-based recycled concrete and its preparation and application in preparing 3D printing components. The low-carbon bio-based recycled concrete in the present application comprises cement: 100 parts; rice husk ash: 10-30 parts; diatomite: 5-15 parts; lignocellulose: 0.01-1.0 parts; steel fiber: 1-3 parts; recycled coarse aggregate: 100-250 parts; recycled fine aggregate: 100-200 parts; water reducing agent: 1-10 parts; retarder: 0.1-2.0 parts; water: 30-60 parts. The low-carbon bio-based recycled concrete of the present application can effectively improve the rheological properties, strength and durability of concrete, and improve its crack resistance while promoting the green transformation of the concrete industry; when further applied to prepare 3D printing components, it can significantly improve the quality and reliability of 3D printing components.

[0006] The purpose of the present application can be achieved by the following technical solutions:

[0007] The first purpose of the present application is to provide a low-carbon bio-based recycled concrete, which comprises the following components by weight:

[0008] Cement: 100 parts; rice husk ash: 10-30 parts; diatomite: 5-15 parts; lignocellulose: 0.01-1.0 parts; steel fiber: 1-3 parts; recycled coarse aggregate: 100-250 parts; recycled fine aggregate: 100-200 parts; water reducing agent: 1-10 parts; retarder: 0.1-2.0 parts; water: 30-60 parts.

[0009] Preferably, the low-carbon bio-based recycled concrete comprises the following weight parts of each component:

[0010] Cement: 100 parts; rice husk ash: 15-25 parts; diatomite: 8-12 parts; lignocellulose: 0.4-0.6 parts; steel fiber: 1.5-2 parts; recycled coarse aggregate: 140-200 parts; recycled fine aggregate: 120-160 parts; water reducing agent: 2-6 parts; retarder: 0.5-1.5 parts; water: 35-50 parts.

[0011] More preferably, the low-carbon bio-based recycled concrete comprises the following weight parts of each component:

[0012] Cement: 100 parts; rice husk ash: 20 parts; diatomite: 10 parts; lignocellulose: 0.5 parts; steel fiber: 1.8 parts; recycled coarse aggregate: 180 parts; recycled fine aggregate: 140 parts; water reducing agent: 4 parts; retarder: 0.8 parts; water: 40 parts.

[0013] In an embodiment of the present application, the strength grade of the cement is ≥42.5 grade, the median particle size is ≤30 μm, and the mass percentage of CaO in the cement is ≥55%.

[0014] In an embodiment of the present application, the activity of SiO2 in the rice husk ash is ≥96, the specific surface area is ≥10 m 2 / g, and D50 is ≤10 μm.

[0015] In an embodiment of the present application, the length of the lignocellulose is 4-14 mm, which is intended to enhance the mechanical properties and anti-cracking properties of the concrete, prevent excessive flow and collapse of the concrete, and improve the overall stability and controllability during construction.

[0016] The length of the steel fiber is 2-10 mm, the diameter is 0.2-0.25 mm, and the tensile strength is 2000-3000 MPa.

[0017] In an embodiment of the present application, the particle size of the recycled coarse aggregate is 5-10 mm, and the particle size of the recycled fine aggregate is 1-5 mm.

[0018] In an embodiment of the present application, the water reducing agent is a polycarboxylic acid water reducing agent, and the retarder is a tartaric acid retarder.

[0019] A second object of the present application is to provide a method for preparing a low-carbon bio-based recycled concrete, comprising the following steps:

[0020] The cement, rice husk ash, diatom mud, lignocellulose, steel fiber, recycled coarse aggregate, recycled fine aggregate, water reducing agent, and water are uniformly mixed to obtain the low-carbon bio-based recycled concrete.

[0021] In an embodiment of the present application, the method specifically comprises the following steps:

[0022] (S1) uniformly mixing the cement, diatom mud, recycled coarse aggregate, recycled fine aggregate, and rice husk ash to obtain a first mixture;

[0023] (S2) adding water to the first mixture obtained in step (S1), and then adding a mixture of lignocellulose, steel fiber, and water reducing agent in batches to obtain the low-carbon bio-based recycled concrete.

[0024] In an embodiment of the present application, in step (S1), the rice husk ash is prepared by the following method:

[0025] (S101) performing acid immersion pretreatment on the rice husk (to reduce the crystallization sensitivity of the rice husk ash to the calcination temperature by removing the metal impurity potassium in the rice husk), and then boiling in a sodium sulfate solution to obtain neutral rice husk after treatment;

[0026] (S102) drying the neutral rice husk obtained in step (S101) and performing combustion treatment to obtain a rice husk ash precursor (to increase the content of amorphous silicon dioxide in the rice husk ash);

[0027] (S103) performing alkali activation treatment on the rice husk ash precursor obtained in step (S102) using a NaOH solution (to enhance the pozzolanic effect of the rice husk ash by changing the chemical environment of SiO2 in the rice husk ash), to obtain pretreated rice husk ash;

[0028] (S104) performing grinding treatment on the pretreated rice husk ash obtained in step (S103) (to enhance the specific surface area of the rice husk ash, thereby maximizing the filling effect of the rice husk ash), to obtain the rice husk ash.

[0029] In an embodiment of the present application, in step (S2), the cement and the rice husk ash are in a completely dry state; the recycled coarse aggregate and the recycled fine aggregate are in a saturated surface dry state (which means that the recycled coarse aggregate and the recycled fine aggregate are saturated by soaking in water and then the excess water on the surface is evaporated to achieve a dry state during further concrete preparation).

[0030] In one embodiment of the present invention, in step (S3), the batch quantitative method refers to adding 1 / 5 of the total amount of cellulose, steel fiber and water-reducing agent each time, in 5 batches.

[0031] The third objective of this invention is to provide an application of low-carbon bio-based recycled concrete in the preparation of 3D printed components.

[0032] Compared with the prior art, the present invention has the following beneficial effects:

[0033] (1) The low-carbon bio-based recycled concrete provided by this invention uses bio-based solid waste - rice husk ash and construction solid waste - recycled aggregate. This improvement not only promotes the recycling of solid waste resources, alleviates the pressure of increasingly scarce natural aggregates, solves the problems of solid waste accumulation and treatment, and reduces carbon emissions in the concrete production process, but also has significant environmental and social effects, meeting the needs of modern society for sustainable and environmentally friendly materials; it helps to promote the green transformation of the concrete industry and has a positive role in promoting the sustainable development of the construction industry.

[0034] (2) In the low-carbon bio-based recycled concrete of the present invention, rice husk ash and diatomaceous earth act as hydrophilic agents, playing a role in regulating the rheological properties of the concrete and controlling its viscosity and fluidity. Specifically, the organic substances in rice husk ash, such as cellulose, starch, and protein, can improve the plasticity and adhesion of the concrete, making it easier to construct; the porous structure and fine particles in diatomaceous earth can also adsorb water, regulate the rheological properties of the concrete, and increase its bonding strength; the introduction of recycled aggregate can slow down the setting speed of the concrete and provide a longer processing time. Since the mineral admixtures and powder particles in the recycled aggregate can absorb some of the water and form cement paste colloid, the free water content in the concrete can be reduced, thereby slowing down the hydration reaction and slowing down the setting speed of the concrete. In addition, by introducing recycled aggregate, the internal friction of the concrete can be increased, making it easier to flow and transport. The granular materials in the recycled aggregate can fill the pore space of the concrete, thereby improving the rheological properties of the concrete and making it easier to flow and form when sprayed or extruded by a 3D printer. This ensures that the material flows smoothly and maintains shape stability during the printing process (allowing for the fabrication of 3D printed components with complex structures and shapes), thereby improving the plasticity and controllability of the 3D printing process.

[0035] (3) In the low-carbon bio-based recycled concrete of the present invention, since the cement paste is alkaline, when the silica of the diatomaceous earth comes into contact with the alkaline substance, the hydroxide ions (OH-) in the alkaline substance... -) will react with the silicon-oxygen bond in the silicon dioxide molecule, which causes the silicon-oxygen bond to break and form silicate ions or silicate ions; the generated silicate ions or silicate ions further react with active oxides in the diatom ooze, such as aluminum oxide (Al2O3), iron oxide (Fe2O3), calcium oxide (CaO), magnesium oxide (MgO), etc., to generate different silicate compounds. These silicate compounds can play a bonding and filling role in the cement paste, further improving the strength and hydration performance of the concrete.

[0036] (4) In the low-carbon bio-based recycled concrete of the present application, the addition of rice husk ash and diatom ooze fills the pores in the concrete, improves the compactness of the concrete, and reduces the occurrence and expansion of cracks. The fine particle filling of rice husk ash can change the stress distribution inside the concrete, increase its tensile strength and crack resistance; the porous structure and special morphology of diatom ooze can absorb the stress during the drying shrinkage and thermal expansion and cold shrinkage of the concrete, effectively preventing the generation of cracks.

[0037] (5) In the preparation of 3D printed components, due to the high water absorption characteristics of recycled aggregates and the need to provide a large amount of free water for hydration reactions in the paste during curing, the introduction of recycled aggregates makes the particle size distribution of the concrete more reasonable, which can improve the interlayer bonding performance of the printed components; thereby solving the problem that the existing 3D printed components often have weak interlayer bonding performance (weak bonding between layers can cause interlayer cracks or interface peeling, etc., affecting the overall stability of the printed components).

[0038] In summary, the low-carbon bio-based recycled concrete of the present application can effectively improve the rheological properties, strength and durability of the concrete, and improve its crack resistance while promoting the green transformation of the concrete industry; when further applied to the preparation of 3D printed components, it can significantly improve the quality and reliability of 3D printed components. DETAILED DESCRIPTION

[0039] The present application provides a low-carbon bio-based recycled concrete, which comprises the following components by weight:

[0040] Cement: 100 parts; rice husk ash: 10-30 parts; diatomite: 5-15 parts; lignocellulose: 0.01-1.0 parts; steel fiber: 1-3 parts; recycled coarse aggregate: 100-250 parts; recycled fine aggregate: 100-200 parts; water reducing agent: 1-10 parts; retarder: 0.1-2.0 parts; water: 30-60 parts.

[0041] Preferably, the low-carbon bio-based recycled concrete comprises the following components by weight:

[0042] Cement: 100 parts; rice husk ash: 15-25 parts; diatomite: 8-12 parts; lignocellulose: 0.4-0.6 parts; steel fiber: 1.5-2 parts; recycled coarse aggregate: 140-200 parts; recycled fine aggregate: 120-160 parts; water reducing agent: 2-6 parts; retarder: 0.5-1.5 parts; water: 35-50 parts.

[0043] More preferably, the low-carbon bio-based recycled concrete comprises the following weight parts of each component:

[0044] Cement: 100 parts; rice husk ash: 20 parts; diatomite: 10 parts; lignocellulose: 0.5 parts; steel fiber: 1.8 parts; recycled coarse aggregate: 180 parts; recycled fine aggregate: 140 parts; water reducing agent: 4 parts; retarder: 0.8 parts; water: 40 parts.

[0045] In an embodiment of the present application, the strength grade of the cement is ≥42.5 grade, the median particle size is ≤30 μm, and the mass percentage of CaO in the cement is ≥55%.

[0046] In an embodiment of the present application, the activity of SiO2 in the rice husk ash is ≥96, the specific surface area is ≥10 m 2 / g, and D50 is ≤10 μm.

[0047] In an embodiment of the present application, the length of the lignocellulose is 4-14 mm, which is intended to enhance the mechanical properties and anti-cracking properties of the concrete, prevent excessive flow and collapse of the concrete, and improve the overall stability and controllability during construction.

[0048] In an embodiment of the present application, the length of the steel fiber is 2-10 mm, the diameter is 0.2-0.25 mm, and the tensile strength is 2000-3000 MPa.

[0049] In an embodiment of the present application, the particle size of the recycled coarse aggregate is 5-10 mm, and the particle size of the recycled fine aggregate is 1-5 mm.

[0050] In an embodiment of the present application, the water reducing agent is a polycarboxylic acid water reducing agent, and the retarder is a tartaric acid retarder.

[0051] The present application provides a preparation method of a low-carbon bio-based recycled concrete, comprising the following steps:

[0052] Mixing cement, rice husk ash, diatom mud, lignocellulose, steel fiber, recycled coarse aggregate, recycled fine aggregate, water reducing agent, retarder, and water to obtain a low-carbon bio-based recycled concrete.

[0053] In an embodiment of the present application, it specifically comprises the following steps:

[0054] (S1) mixing cement, diatom ooze, recycled coarse aggregate, recycled fine aggregate and rice husk ash to obtain a first mixture;

[0055] (S2) adding water to the first mixture obtained in step (S1), and then adding a mixture of lignocellulose, steel fiber and water reducing agent batch by batch to obtain a low-carbon bio-based recycled concrete.

[0056] In an embodiment of the present application, in step (S1), the rice husk ash is prepared by the following method:

[0057] (S101) subjecting the rice husk to acid immersion pretreatment (to reduce the crystallization sensitivity of the rice husk ash to the calcination temperature by removing the metal impurity potassium in the rice husk), and then boiling in a sodium sulfate solution to obtain neutral rice husk after treatment;

[0058] (S102) drying the neutral rice husk obtained in step (S101) and then subjecting it to combustion treatment to obtain a rice husk ash precursor (to increase the content of amorphous silicon dioxide in the rice husk ash);

[0059] (S103) subjecting the rice husk ash precursor obtained in step (S102) to alkali activation treatment using a NaOH solution (to enhance the pozzolanic effect of the rice husk ash by changing the chemical environment of SiO2 in the rice husk ash), to obtain pretreated rice husk ash;

[0060] (S104) grinding the pretreated rice husk ash obtained in step (S103) (to increase the specific surface area of the rice husk ash, thereby maximizing the filling effect of the rice husk ash), to obtain the rice husk ash.

[0061] In an embodiment of the present application, in step (S2), the cement and the rice husk ash are both in a completely dry state; the recycled coarse aggregate and the recycled fine aggregate are both in a saturated surface dry state (which means that the recycled coarse aggregate and the recycled fine aggregate are saturated by soaking in water, and then the excess water on the surface is evaporated to achieve a dry state).

[0062] In an embodiment of the present application, in step (S3), the batched and quantified addition means that 1 / 5 of the total amount of lignocellulose, steel fiber and water reducing agent is added each time, and the addition is performed 5 times.

[0063] The present application provides a low-carbon bio-based recycled concrete for preparing 3D printed components.

[0064] The present application will be described in detail below with reference to specific embodiments.

[0065] In the following examples, unless otherwise specified, the reagents used are commercially available reagents, and the detection means and methods used are conventional detection means and methods in the art.

[0066] Example 1

[0067] The present embodiment provides a rice husk ash and a preparation method thereof, specifically comprising the following steps:

[0068] (A1) 6 kg of rice husk was poured into 60 L of 0.01 mol / L sodium sulfate solution and stirred and boiled in a 150 L stainless steel cylindrical storage tank for 2 h, and then thoroughly washed with tap water until the rice husk was in a neutral state to obtain neutral rice husk;

[0069] (A2) The neutral rice husk prepared in step (A1) was cooled at room temperature and dried for three days, and then placed in a high-temperature incineration resistance furnace, burned at an extreme temperature of 650℃ for 1 h, and then cooled at a decreasing speed of 10℃ / min to obtain a rice husk ash precursor;

[0070] (A3) The rice husk ash precursor prepared in step (A2) was subjected to alkali activation treatment using a 3% concentration NaOH solution to obtain a pretreated rice husk ash;

[0071] (A4) The pretreated rice husk ash prepared in step (A3) was subjected to grinding treatment using a super micro vortex grinder to obtain a rice husk ash.

[0072] The rice husk ash prepared in the present embodiment has an amorphous silicon dioxide content of 99.26%, a specific surface area of 143.82 m 2 / g, and a median particle size of 0.76 μm.

[0073] Comparative Example 1

[0074] The present comparative example provides a rice husk ash and a preparation method thereof, specifically comprising the following steps:

[0075] (A1) 6 kg of rice husk was poured into 60 L of 0.01 mol / L sodium sulfate solution and stirred and boiled in a 150 L stainless steel cylindrical storage tank for 2 h, and then thoroughly washed with tap water until the rice husk was in a neutral state to obtain neutral rice husk;

[0076] (A2) The neutral rice husk prepared in step (A1) was cooled at room temperature and dried for three days, and then placed in a high-temperature incineration resistance furnace, burned at 200℃ for 1 h, and then cooled at a decreasing speed of 10℃ / min to obtain a rice husk ash precursor;

[0077] (A3) The rice husk ash precursor prepared in step (A2) was subjected to alkali activation treatment using a 3% concentration NaOH solution to obtain a pretreated rice husk ash;

[0078] (A4) The pretreated rice husk ash prepared in step (A3) was subjected to grinding treatment using a super micro vortex grinder to obtain a rice husk ash.

[0079] The amorphous silicon dioxide content of the rice husk ash prepared in this comparative example is 96.74%, the specific surface area is 126.73 m 2 / g, and the median particle size is 2.21 μm.

[0080] Comparative Example 2

[0081] This comparative example provides a rice husk ash and a preparation method thereof, specifically comprising the following steps:

[0082] (A1) 6 kg of rice husk is poured into 60 L of 0.01 mol / L sodium sulfate solution and stirred and boiled in a 150 L stainless steel cylindrical storage tank for 2 h, and then thoroughly washed with tap water until the rice husk is in a neutral state to obtain neutral rice husk;

[0083] (A2) The neutral rice husk prepared in step (A1) is cooled at room temperature and dried for three days, and then placed in a high-temperature incineration resistance furnace, burned at an extreme temperature of 650°C for 1 h, and then cooled at a reduction rate of 10°C / min to obtain a rice husk ash precursor;

[0084] (A3) The rice husk ash precursor prepared in step (A2) is ground using a super micro vortex grinder to obtain a rice husk ash.

[0085] The amorphous silicon dioxide content of the rice husk ash prepared in this comparative example is 95.82%, the specific surface area is 128.17 m 2 / g, and the median particle size is 4.29 μm.

[0086] Comparative Example 3

[0087] This comparative example provides a rice husk ash and a preparation method thereof, specifically comprising the following steps:

[0088] (A1) 6 kg of rice husk is poured into 60 L of 0.01 mol / L sodium sulfate solution and stirred and boiled in a 150 L stainless steel cylindrical storage tank for 2 h, and then thoroughly washed with tap water until the rice husk is in a neutral state to obtain neutral rice husk;

[0089] (A2) The neutral rice husk prepared in step (A1) is cooled at room temperature and dried for three days, and then placed in a high-temperature incineration resistance furnace, burned at an extreme temperature of 650°C for 1 h, and then cooled at a reduction rate of 10°C / min to obtain a rice husk ash precursor;

[0090] (A3) The rice husk ash precursor prepared in step (A2) is subjected to alkali activation treatment using a 3% concentration NaOH solution, and dried to obtain a rice husk ash.

[0091] The amorphous silicon dioxide content of the rice husk ash prepared in this comparative example is 98.66%, the specific surface area is 36.82 m 2 / g, and the median particle size is 36.8 μm. Compared with Example 1, the particle size of the rice husk ash is larger and the specific surface area is smaller due to the lack of a grinding process.

[0092] Example 2

[0093] This example provides a low-carbon bio-based recycled concrete, which comprises the following components by weight:

[0094] Cement: 100 parts; rice husk ash: 20 parts; diatomite: 10 parts; lignocellulose: 0.5 parts; steel fiber: 1.8 parts; recycled coarse aggregate: 180 parts; recycled fine aggregate: 140 parts; water reducing agent: 4 parts; retarder: 0.8 parts; water: 40 parts.

[0095] The cement is P.O 42.5 ordinary portland cement, which meets GB / T 175-2007, has CaO≥60%, and D50≤20 μm; the rice husk ash is prepared in Example 1; the lignocellulose has a length of 8-12 mm; the steel fiber is copper-plated straight steel fiber, has a length of 8 mm, a diameter of 0.2 mm, and a tensile strength of 2500 MPa; the recycled fine aggregate and the recycled concrete coarse aggregate are obtained by crushing waste concrete, the particle size range of the recycled fine aggregate is 3-5 mm, and the particle size range of the recycled coarse aggregate is 5-8 mm; the water reducing agent is a polycarboxylic acid high-efficiency water reducing agent (Jiangsu Subote New Material Technology Co., Ltd.) with a solid content of 40%; the retarder is a tartaric acid retarder; and the water is tap water.

[0096] During preparation, the following steps are specifically included:

[0097] (S1) The cement, recycled coarse aggregate, recycled fine aggregate, and rice husk ash are sequentially poured into a 50 L mixer for stirring (stirring speed: 50 revolutions / min, stirring time: 3 min) to obtain a first mixture;

[0098] (S2) The lignocellulose, steel fiber, and water reducing agent are stirred and mixed uniformly to obtain a second mixture;

[0099] (S3) The water is added to the first mixture prepared in step (S1) for stirring, and then the second mixture prepared in step (S2) is added in 5 times (1 / 5 each time) (stirring speed: 50 revolutions / min, stirring time: 18 min, 1 / 5 of the second mixture is added every 3 min of stirring) to obtain a low-carbon bio-based recycled concrete.

[0100] Example 3

[0101] The difference between this embodiment and embodiment 2 is that the low-carbon bio-based recycled concrete of this embodiment comprises the following components by weight:

[0102] Cement: 100 parts; rice husk ash: 15 parts; diatomite: 12 parts; lignocellulose: 0.4 parts; steel fiber: 2 parts; recycled coarse aggregate: 140 parts; recycled fine aggregate: 160 parts; water reducing agent: 2 parts; retarder: 1.5 parts; water: 35 parts.

[0103] Example 4

[0104] The difference between this embodiment and embodiment 2 is that the low-carbon bio-based recycled concrete of this embodiment comprises the following components by weight:

[0105] Cement: 100 parts; rice husk ash: 25 parts; diatomite: 8 parts; lignocellulose: 0.6 parts; steel fiber: 1.5 parts; recycled coarse aggregate: 200 parts; recycled fine aggregate: 120 parts; water reducing agent: 6 parts; retarder: 0.5 parts; water: 50 parts.

[0106] Example 5

[0107] The difference between this embodiment and embodiment 2 is that the low-carbon bio-based recycled concrete of this embodiment comprises the following components by weight:

[0108] Cement: 100 parts; rice husk ash: 22 parts; diatomite: 9 parts; lignocellulose: 0.5 parts; steel fiber: 1.7 parts; recycled coarse aggregate: 160 parts; recycled fine aggregate: 130 parts; water reducing agent: 5 parts; retarder: 1.0 parts; water: 45 parts.

[0109] Example 6

[0110] The difference between this embodiment and embodiment 2 is that the low-carbon bio-based recycled concrete of this embodiment comprises the following components by weight:

[0111] Cement: 100 parts; rice husk ash: 10 parts; diatomite: 15 parts; lignocellulose: 0.01 parts; steel fiber: 3 parts; recycled coarse aggregate: 100 parts; recycled fine aggregate: 200 parts; water reducing agent: 1 part; retarder: 2 parts; water: 30 parts.

[0112] Example 7

[0113] The difference between this embodiment and embodiment 2 is that the low-carbon bio-based recycled concrete of this embodiment comprises the following components by weight:

[0114] Cement: 100 parts; rice husk ash: 30 parts; diatomite: 5 parts; lignocellulose: 1 part; steel fiber: 1 part; recycled coarse aggregate: 250 parts; recycled fine aggregate: 100 parts; water reducing agent: 10 parts; retarder: 0.1 part; water: 60 parts.

[0115] Example 8

[0116] This example differs from Example 2 in that the low-carbon bio-based recycled concrete of this example includes the following parts by weight of each component:

[0117] Cement: 100 parts; rice husk ash: 18 parts; diatomite: 12 parts; lignocellulose: 0.8 part; steel fiber: 2.5 parts; recycled coarse aggregate: 220 parts; recycled fine aggregate: 180 parts; water reducing agent: 8 parts; retarder: 1.2 parts; water: 55 parts.

[0118] Comparative Example 4

[0119] This comparative example differs from Example 2 in that this comparative example does not use rice husk ash.

[0120] Comparative Example 5

[0121] This comparative example differs from Example 2 in that this comparative example uses the rice husk ash prepared in Comparative Example 1.

[0122] Comparative Example 6

[0123] This comparative example differs from Example 2 in that this comparative example uses the rice husk ash prepared in Comparative Example 2.

[0124] Comparative Example 7

[0125] This comparative example differs from Example 2 in that this comparative example uses the rice husk ash prepared in Comparative Example 3.

[0126] Comparative Example 8

[0127] This comparative example differs from Example 2 in that this comparative example uses a commercially available rice husk ash (silicon dioxide content in the rice husk ash is 83.69%, specific surface area is 18.93 m 2 / g, and median particle size is 66.52 pm).

[0128] Comparative Example 9

[0129] This comparative example differs from Example 2 in that this comparative example does not use diatomite.

[0130] Comparative Example 10

[0131] This comparative example differs from Example 2 in that this comparative example does not use recycled coarse aggregate and recycled fine aggregate.

[0132] Example 9

[0133] The present example provides a 3D printed component and a preparation method thereof, specifically comprising the following steps:

[0134] The low-carbon bio-based recycled concrete prepared in Example 2 is used to prepare a 3D printed component, which is cut by a full-automatic infrared stone cutting machine, then polished by a double-end surface grinding machine, and the X / Y / Z directions are marked on the surface of the test piece. The loading direction of mechanical properties and crack resistance is Z direction, and the strength value of each loading direction is determined by calculating the average strength of three test pieces. For detailed preparation method, refer to the following literature disclosure: Liu Hua-wei, Liu Chao, Bai Guoliang, et al. Experimental study on mechanical properties of 3D printed coarse aggregate concrete based on pore structure defects [J]. Journal of Civil Engineering, 2022, 55(12): 11.

[0135] Example 10

[0136] The difference between the present example and Example 9 is that the low-carbon bio-based recycled concrete prepared in Example 3 is used to prepare a 3D printed component in the present example.

[0137] Example 11

[0138] The difference between the present example and Example 9 is that the low-carbon bio-based recycled concrete prepared in Example 4 is used to prepare a 3D printed component in the present example.

[0139] Example 12

[0140] The difference between the present example and Example 9 is that the low-carbon bio-based recycled concrete prepared in Example 5 is used to prepare a 3D printed component in the present example.

[0141] Example 13

[0142] The difference between the present example and Example 9 is that the low-carbon bio-based recycled concrete prepared in Example 6 is used to prepare a 3D printed component in the present example.

[0143] Example 14

[0144] The difference between the present example and Example 9 is that the low-carbon bio-based recycled concrete prepared in Example 7 is used to prepare a 3D printed component in the present example.

[0145] Example 15

[0146] The difference between the present example and Example 9 is that the low-carbon bio-based recycled concrete prepared in Example 8 is used to prepare a 3D printed component in the present example.

[0147] Comparative Example 11

[0148] This comparative example differs from Example 9 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 4.

[0149] Comparative Example 12

[0150] This comparative example differs from Example 9 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 5.

[0151] Comparative Example 13

[0152] This comparative example differs from Example 11 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 6.

[0153] Comparative Example 14

[0154] This comparative example differs from Example 9 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 7.

[0155] Comparative Example 15

[0156] This comparative example differs from Example 9 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 8.

[0157] Comparative Example 16

[0158] This comparative example differs from Example 9 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 9.

[0159] Comparative Example 17

[0160] This comparative example differs from Example 9 in that the 3D printed component was prepared using the low-carbon bio-based recycled concrete prepared in Comparative Example 10.

[0161] Performance tests:

[0162] 1) The mechanical performance test was performed according to the method specified in GB / T 50081-2019, and the results are shown in Table 1.

[0163] 2) The crack resistance test was performed according to the method specified in GB / T 50082-2009, and the results are shown in Table 1.

[0164] Table 1 Summary of performance tests for Examples 2-15 and Comparative Examples 4-17

[0165]

[0166]

[0167]

[0168] It can be found from Table 1 that the low-carbon bio-based recycled concrete of the application can effectively improve the rheological properties, strength and durability of concrete and improve the crack resistance while promoting the green transformation of the concrete industry. When it is further applied to prepare 3D printing components, the quality and reliability of the 3D printing components can be significantly improved. In addition, when the ratio of the low-carbon bio-based recycled concrete is: cement 100 parts, rice husk ash 10-50 parts, diatomite 5-25 parts, lignocellulose 0.01-1.0 parts, steel fiber 1-3 parts, recycled coarse aggregate 100-250 parts, recycled fine aggregate 100-200 parts, water reducing agent 0.1-1.0 parts, retarder 0.1-2.0 parts, and water 30-60 parts, the synergy between the components is optimal, and the mechanical properties and crack resistance are optimal.

[0169] It can be seen from Example 2 and Comparative Examples 5-8 that the higher the amorphous calcium oxide content, the larger the specific surface area, and the smaller the particle size of the rice husk ash, the greater the compressive strength and the greater the flexural strength of the concrete, and the better the crack resistance (the smaller the corresponding crack width).

[0170] In addition, compared with concrete, the compressive strength and flexural strength of the 3D printing component will decrease and the crack width will increase under the same ratio.

[0171] The above description of the embodiments is to facilitate the understanding and use of the application by those skilled in the art. Those skilled in the art can easily make various modifications to these embodiments and apply the general principles described herein to other embodiments without creative labor. Therefore, the application is not limited to the above embodiments, and improvements and modifications made by those skilled in the art without departing from the scope of the application should be within the scope of protection of the application.

Claims

1. A low carbon bio-based recycled concrete, characterized in that, The following components are included by weight parts: Cement: 100 parts; rice husk ash: 10-30 parts; diatom ooze: 5-15 parts; Lignocellulose: 0.01-1.0 parts; steel fiber: 1-3 parts; recycled coarse aggregate: 100-250 parts; recycled fine aggregate: 100-200 parts; Water reducing agent: 1-10 parts; retarder: 0.1-2.0 parts; water: 30-60 parts; The cement has a strength grade of ≥ 42.5, a median particle size of ≤ 30 μm, and CaO in the cement has a mass percentage of ≥ 55%; the rice husk ash has active SiO2 of ≥ 96%, a specific surface area of ≥ 10 m 2 / g, and D50 of ≤ 10 μm. The rice husk ash is prepared by the following method: (S101) The rice husk is acid immersed for pretreatment, then boiled in a sodium sulfate solution, and post-treated to obtain neutral rice husk; (S102) The neutral rice husk obtained in step (S101) is dried and then subjected to combustion treatment, and cooled to obtain rice husk ash precursor; (S103) The rice husk ash precursor obtained in step (S102) is subjected to alkali activation treatment using a NaOH solution to obtain pretreated rice husk ash; (S104) The pretreated rice husk ash obtained in step (S103) is ground to obtain rice husk ash.

2. A low carbon bio-based recycled concrete according to claim 1, characterized in that, The length of the lignocellulose is 4-14 mm; The length of the steel fiber is 2-10 mm, the diameter is 0.2-0.25 mm, and the tensile strength is 2000-3000 MPa.

3. A low carbon bio-based recycled concrete according to claim 1, characterized in that, The particle size of the recycled coarse aggregate is 5-10 mm; the particle size of the recycled fine aggregate is 1-5 mm.

4. The low carbon bio-based recycled concrete of claim 1, wherein, The water reducing agent is a polycarboxylic acid water reducing agent; the retarder is a tartaric acid retarder.

5. A method of producing low carbon bio-based recycled concrete according to any one of claims 1-4, characterized in that, The following steps are included: Mixing cement, rice husk ash, diatom ooze, lignocellulose, steel fiber, recycled coarse aggregate, recycled fine aggregate, water reducing agent, retarder, and water to obtain low-carbon bio-based recycled concrete.

6. Use of the low-carbon bio-based recycled concrete according to any one of claims 1-4 in the preparation of 3D printed components.

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