A green building material and preparation method thereof

Abstract

The present invention relates to a green building material and a preparation method thereof, and belongs to the technical field of building materials. The material comprises the following raw materials by weight: 200-500 parts of slag, 100-200 parts of diatomaceous earth, 60-150 parts of sodium sulfate, 120-230 parts of alkaline activator, 400-600 parts of coarse aggregate and 200-300 parts of fine aggregate; wherein the coarse aggregate comprises waste rubber and ceramsite; the fine aggregate comprises river sand and modified bamboo fiber; wherein the modified bamboo fiber is cellulose nanofiber modified bamboo fiber. The green building material of the present invention belongs to geopolymer concrete, adopts renewable materials such as bamboo and industrial waste such as slag and waste rubber as raw materials, reduces the use of natural resources and energy, can effectively improve the utilization efficiency of materials, and belongs to green environmental protection materials.

Description

Technical Field

[0001] The invention relates to the technical field of building materials, and in particular to a green building material and a preparation method thereof. Background Art

[0002] Green buildings aim to reduce energy consumption, reduce carbon dioxide emissions, and improve indoor environmental quality, aiming to achieve harmonious coexistence between humans and nature. However, in the practice of green buildings, material selection and evaluation has become a key issue. Traditional building materials usually have problems such as energy-intensive production, high pollution emissions, and short service life, making it difficult to meet the requirements of green buildings.

[0003] Various industrial solid wastes are used to replace cement to prepare low-carbon cementitious materials, such as blast furnace slag, fly ash and silica fume. However, due to factors such as solid waste composition and activity, the types and amounts of solid waste that can be used in the current cement production process are limited, and there are still many outstanding problems that need to be solved. Summary of the invention

[0004] The purpose of the present invention is to overcome the shortcomings of the prior art and provide a green building material and a preparation method thereof, mainly using waste tire solid waste.

[0005] To achieve the above object, the technical solution adopted by the present invention is:

[0006] In a first aspect, the present invention provides a green building material, comprising the following raw materials in parts by weight: 200-500 parts of slag, 100-200 parts of diatomaceous earth, 60-150 parts of sodium sulfate, 120-230 parts of alkaline activator, 400-600 parts of coarse aggregate and 200-300 parts of fine aggregate; wherein the coarse aggregate comprises waste rubber and ceramsite; the fine aggregate comprises river sand and modified bamboo fiber; wherein the modified bamboo fiber is cellulose nanofiber (CNFs) modified bamboo fiber.

[0007] The green building material of the present invention is a silicate material produced by using slag and diatomite as main raw materials under the action of alkaline activator, which belongs to geopolymer concrete. Slag is a byproduct in the blast furnace ironmaking process. In the ironmaking process, iron oxide is reduced to metallic iron at high temperature, and impurities such as silicon dioxide and aluminum oxide in iron ore react with lime and the like to generate a molten material with silicate and aluminosilicate as main components, which is quenched into a loose and porous granular material, namely blast furnace slag, referred to as slag. The chemical composition of diatomite is mainly SiO2, containing a small amount of Al2O3, Fe2O3, CaO, MgO and organic matter, and it has the properties of being fine, loose, light, porous, water-absorbent and permeable. Therefore, by using slag and diatomite as the skeleton, waste rubber can increase the toughness and ductility of concrete. Moreover, recycling and treating waste rubber and using it as one of the coarse aggregates of concrete can effectively reduce environmental hazards and reduce the exploitation of natural resources. Moreover, the addition of waste rubber and modified bamboo fiber can effectively reduce the total amount of aggregate. At the same time, using modified bamboo fiber as fine aggregate can also improve the impact resistance of the material.

[0008] Preferably, the preparation method of the modified bamboo fiber comprises the following steps: firstly preparing a mixed solution of cellulose nanofibers, a grafting resin and a coupling agent, and then spraying the mixed solution on the surface of the bamboo fiber, and after drying, obtaining the cellulose nanofiber-modified bamboo fiber; wherein the mass ratio of the grafting resin, the coupling agent and the cellulose nanofibers is 1:(18-20):(20-60); and the mass ratio of the mixed solution to the bamboo fiber is (20-60):1.

[0009] Preferably, the grafted resin is glycidyl methacrylate; the coupling agent is at least one of the silane coupling agents KH550, KH570, and KH560, and more preferably, the coupling agent is KH550.

[0010] Preferably, the mass ratio of the waste rubber to ceramsite is (2-2.5):1; and the particle size of the coarse aggregate is 5-10 mm.

[0011] Preferably, the mass ratio of the river sand to the modified bamboo fiber is (2.5-3):1; and the particle size of the fine aggregate is 1-4 mm.

[0012] Preferably, the waste rubber is oxidatively modified waste rubber, and the modification method is to soak the waste rubber in a hydrogen peroxide solution with a mass concentration of (20-30)% for 2-3 hours, then take it out for rinsing, and dry it to obtain the oxidatively modified waste rubber.

[0013] Preferably, the alkaline activator is sodium hydroxide.

[0014] In a second aspect, the present invention provides a method for preparing a green building material, comprising the following steps:

[0015] (1) Sodium sulfate is first added to water to form a slurry, and then the slurry is used to wet grind the slag to obtain a mixed paste of slag and sodium sulfate. Because strong alkali may cause alkali aggregation reaction and chloride salts can easily cause steel bars to rust, sodium sulfate is used as a chemical activator for wet grinding of slag.

[0016] (2) Diatomaceous earth, sodium sulfate, coarse aggregate and fine aggregate are stirred and mixed evenly, and then the mixed paste of slag and sodium sulfate and the alkaline activator solution are added and mixed, and then poured into a mold for curing. After demolding, the green building material is obtained.

[0017] Preferably, in step S2, the curing time is 12 to 24 hours.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] (1) The green building material of the present invention is an aluminosilicate material produced by using slag and diatomaceous earth as main raw materials under the action of an alkaline activator, and belongs to geopolymer concrete. Among them, recycling waste rubber and using it as one of the coarse aggregates of concrete can effectively reduce environmental harm and reduce the exploitation of natural resources. In addition, adding waste rubber and modified bamboo fiber can effectively reduce the total amount of aggregate, and using modified bamboo fiber as fine aggregate can also improve the impact resistance of the material. Therefore, the building material of the present invention uses renewable materials such as bamboo and industrial waste such as slag and waste rubber as raw materials, reduces the use of natural resources and energy, and can effectively improve the utilization efficiency of materials, and belongs to green environmental protection materials.

[0020] (2) In the preparation method of the green building material of the present invention, the slag is firstly wet-grinded with sodium sulfate, which can reduce the crystallinity of the slag, increase the lattice distortion of the slag structure, produce more amorphous substances, and increase the surface free energy and reactivity of the material, thereby improving the mechanical properties of the material.

[0021] (3) The waste rubber of the present invention is oxidatively modified waste rubber, and the specific operation is to soak it in hydrogen peroxide. Hydrogen peroxide has a strong decontamination and oxidation effect, which can help remove impurities on the surface of waste rubber particles that cannot be removed by mechanical crushing, such as heavy oil, carbon black, etc. The surface of the waste rubber treated with hydrogen peroxide is smoother, and as a coarse aggregate of geopolymer concrete, it can be better integrated with other components, and it is not easy to crack later. It can also further improve the mechanical properties of the material, especially the compressive strength. DETAILED DESCRIPTION

[0022] In order to better illustrate the purpose, technical solutions and advantages of the present invention, the present invention will be further described below in conjunction with specific embodiments.

[0023] The raw materials used in the specific embodiment are as follows:

[0024] Slag: The manufacturer is Zhaochen Mineral Products Co., Ltd., Lingshou County, Shijiazhuang City, Hebei Province;

[0025] Diatomaceous earth: The manufacturer is Xucheng Product Processing Factory in Lingshou County, Shijiazhuang City, Hebei Province;

[0026] Sodium sulfate: The manufacturer is Hubei Shuanghuan Technology Co., Ltd.

[0027] Alkaline activator: flake sodium hydroxide, manufactured by Inner Mongolia Junzheng Energy Chemical Co., Ltd.

[0028] Waste rubber: from waste tires, purchased from Huiju Tire Auto Parts (Guangzhou) Co., Ltd.;

[0029] Bamboo fiber: bamboo raw fiber, the manufacturer is Anji Tanzhuzhuang Bamboo Fiber Co., Ltd.

[0030] Cellulose nanofiber: The manufacturer is Hubei Handafei Biotechnology Co., Ltd.

[0031] Glycidyl methacrylate: The manufacturer is Shandong Daoqin Chemical Co., Ltd.;

[0032] Silane coupling agent: The manufacturer is Shandong Yuanjin New Materials Co., Ltd., the brands are KH550, KH570, and KH560.

[0033] Unless otherwise specified, other materials, reagents, etc. used in the examples can be obtained from commercial sources.

[0034] Example 1

[0035] A green building material, comprising the following raw materials by weight: 367 parts of slag, 134 parts of diatomaceous earth, 104 parts of sodium sulfate, 226 parts of alkaline activator, 510 parts of coarse aggregate and 255 parts of fine aggregate; wherein the coarse aggregate comprises waste rubber and ceramsite; the fine aggregate comprises river sand and modified bamboo fiber; wherein the modified bamboo fiber is cellulose nanofiber (CNFs) modified bamboo fiber. The mass ratio of the waste rubber to ceramsite is 2.3:1; the particle size of the coarse aggregate is 5-10 mm. The mass ratio of the river sand to the modified bamboo fiber is 2.8:1; the particle size of the fine aggregate is 1-4 mm. The alkaline activator is sodium hydroxide.

[0036] The preparation method of the modified bamboo fiber comprises the following steps: firstly preparing a mixed solution of cellulose nanofibers, grafting resin and coupling agent, and then spraying the mixed solution on the surface of bamboo fiber, and drying to obtain the bamboo fiber modified by cellulose nanofibers; wherein the mass ratio of grafting resin, coupling agent and cellulose nanofibers is 1:19:50; and the mass ratio of the mixed solution to bamboo fiber is 50:1. wherein the grafting resin is glycidyl methacrylate; and the coupling agent is silane coupling agent KH550. wherein the waste rubber is oxidatively modified waste rubber, and the modification method thereof is to soak the waste rubber in a hydrogen peroxide solution with a mass concentration of 25% for 2.5 hours, then take it out for rinsing, and dry it to obtain the oxidatively modified waste rubber.

[0037] A method for preparing a green building material comprises the following steps:

[0038] (1) Sodium sulfate is first added to water to form a slurry, and then the slurry is used to wet grind the slag to obtain a mixed paste of slag and sodium sulfate.

[0039] (2) The diatomaceous earth, sodium sulfate, coarse aggregate and fine aggregate are stirred and mixed evenly, and then the mixed paste of slag and sodium sulfate and the alkaline activator solution are added and mixed, and then poured into a mold for curing for 20 hours. After demolding, the green building material is obtained.

[0040] Example 2

[0041] A green building material comprises the following raw materials in parts by weight: 200 parts of slag, 100 parts of diatomite, 60 parts of sodium sulfate, 120 parts of alkaline activator, 400 parts of coarse aggregate and 200 parts of fine aggregate; wherein the coarse aggregate comprises waste rubber and ceramsite; the fine aggregate comprises river sand and modified bamboo fiber; wherein the modified bamboo fiber is cellulose nanofiber (CNFs) modified bamboo fiber. The mass ratio of the waste rubber to ceramsite is 2:1; the particle size of the coarse aggregate is 5-10 mm. The mass ratio of the river sand to the modified bamboo fiber is 2.5:1; the particle size of the fine aggregate is 1-4 mm. The alkaline activator is sodium hydroxide.

[0042] The preparation method of the modified bamboo fiber comprises the following steps: firstly preparing a mixed solution of cellulose nanofibers, grafting resin and coupling agent, and then spraying the mixed solution on the surface of bamboo fiber, and drying to obtain the bamboo fiber modified by cellulose nanofibers; wherein the mass ratio of grafting resin, coupling agent and cellulose nanofibers is 1:18:20; and the mass ratio of the mixed solution to bamboo fiber is 20:1. wherein the grafting resin is glycidyl methacrylate; and the coupling agent is silane coupling agent KH570. the waste rubber is oxidatively modified waste rubber, and the modification method thereof is to soak the waste rubber in a hydrogen peroxide solution with a mass concentration of 20% for 3 hours, then take it out for rinsing, and dry it to obtain the oxidatively modified waste rubber.

[0043] A method for preparing a green building material comprises the following steps:

[0044] (1) Sodium sulfate is first added to water to form a slurry, and then the slurry is used to wet grind the slag to obtain a mixed paste of slag and sodium sulfate. Because strong alkali may cause alkali aggregation reaction and chloride salts can easily cause steel bars to rust, sodium sulfate is used as a chemical activator for wet grinding of slag.

[0045] (2) The diatomaceous earth, sodium sulfate, coarse aggregate and fine aggregate are stirred and mixed evenly, and then the mixed paste of slag and sodium sulfate and the alkaline activator solution are added and mixed, and then poured into a mold for curing for 12 hours. After demolding, the green building material is obtained.

[0046] Example 3

[0047] A green building material, comprising the following raw materials in parts by weight: 500 parts of slag, 200 parts of diatomite, 150 parts of sodium sulfate, 230 parts of alkaline activator, 600 parts of coarse aggregate and 300 parts of fine aggregate; wherein the coarse aggregate comprises waste rubber and ceramsite; the fine aggregate comprises river sand and modified bamboo fiber; wherein the modified bamboo fiber is cellulose nanofiber (CNFs) modified bamboo fiber. The mass ratio of the waste rubber to ceramsite is 2.5:1; the particle size of the coarse aggregate is 5-10 mm. The mass ratio of the river sand to the modified bamboo fiber is 3:1; the particle size of the fine aggregate is 1-4 mm. The alkaline activator is sodium hydroxide.

[0048] The preparation method of the modified bamboo fiber comprises the following steps: firstly preparing a mixed solution of cellulose nanofibers, grafting resin and coupling agent, and then spraying the mixed solution on the surface of bamboo fiber, and drying to obtain the bamboo fiber modified by cellulose nanofibers; wherein the mass ratio of grafting resin, coupling agent and cellulose nanofibers is 1:20:60; and the mass ratio of the mixed solution to bamboo fiber is 60:1. wherein the grafting resin is glycidyl methacrylate; and the coupling agent is silane coupling agent KH560. the waste rubber is oxidatively modified waste rubber, and the modification method thereof is to soak the waste rubber in a hydrogen peroxide solution with a mass concentration of 30% for 2 hours, then take it out for rinsing, and dry it to obtain the oxidatively modified waste rubber.

[0049] A method for preparing a green building material comprises the following steps:

[0050] (1) Sodium sulfate is first added to water to form a slurry, and then the slurry is used to wet grind the slag to obtain a mixed paste of slag and sodium sulfate. Because strong alkali may cause alkali aggregation reaction and chloride salts can easily cause steel bars to rust, sodium sulfate is used as a chemical activator for wet grinding of slag.

[0051] (2) The diatomaceous earth, sodium sulfate, coarse aggregate and fine aggregate are stirred and mixed evenly, and then the mixed paste of slag and sodium sulfate and the alkaline activator solution are added and mixed, and then poured into a mold for curing for 12-24 hours. After demolding, the green building material is obtained.

[0052] Example 4

[0053] The difference between Example 4 and Example 1 is that the waste rubber used in Example 4 has not been oxidized.

[0054] Example 5

[0055] The difference between Example 5 and Example 1 is that the mass ratio of the waste rubber and ceramsite in Example 5 is 1:1.

[0056] Example 6

[0057] The difference between Example 6 and Example 1 is that the mass ratio of waste rubber to ceramsite in Example 6 is 3:1.

[0058] Example 7

[0059] The difference between Example 7 and Example 1 is that the mass ratio of river sand to modified bamboo fiber in Example 7 is 2:1.

[0060] Example 8

[0061] The difference between Example 8 and Example 1 is that the mass ratio of river sand to modified bamboo fiber in Example 8 is 3.5:1.

[0062] Example 9

[0063] The difference between Example 9 and Example 1 is that in the green material preparation process of Example 9, the slag is not wet-grinded with sodium sulfate, and the sodium sulfate is directly mixed with other ingredients.

[0064] Comparative Example 1

[0065] The difference between Comparative Example 1 and Example 1 is that: in Comparative Example 1, no modified bamboo fiber is added, and the fine aggregate contains only river sand.

[0066] Comparative Example 2

[0067] The difference between Comparative Example 2 and Example 1 is that the bamboo fibers in Comparative Example 2 are not modified by cellulose nanofibers.

[0068] Comparative Example 3

[0069] The difference between Comparative Example 3 and Example 1 is that: in Comparative Example 4, no sodium sulfate is added.

[0070] Comparative Example 4

[0071] The difference between Comparative Example 4 and Example 1 is that: Comparative Example 4 does not add sodium sulfate, but uses sodium chloride instead.

[0072] Comparative Example 5

[0073] The difference between Comparative Example 5 and Example 1 is that: Comparative Example 5 does not add sodium sulfate, but uses sodium hydroxide instead.

[0074] Comparative Example 6

[0075] The difference between Comparative Example 6 and Example 1 is that: in Comparative Example 6, no waste rubber is added, and the coarse aggregate is only ceramsite.

[0076] Performance Testing

[0077] The geopolymer concrete of Examples 1 to 9 and Comparative Examples 1 to 6 was made into a cubic specimen with a side length of 150 mm. According to the method of GB / T 50081-2019, a hydraulic universal testing machine was used to obtain the failure load and bearing area of ​​the sample, and the compressive strength was calculated by the following formula:

[0078] ;

[0079] Among them, f cc -compressive strength of concrete cube specimen (MPa), F-specimen failure load (N); A-specimen pressure bearing area (mm 2 ), see Table 1 for specific data.

[0080] Then, according to the method of GB / T 50081-2019, a hydraulic universal testing machine was used to obtain the failure load and bearing area of ​​the sample, and the bond strength was calculated by the following formula:

[0081] ;

[0082] Where, fb-bonding strength (MPa); F-failure load (N); A-bonding surface area of ​​specimen (mm 2 ). Specific data are shown in Table 1.

[0083] Table 1 Compressive strength and bonding strength of samples in each group

[0084] Group Compressive strength / MPa Bond strength (MPa) Example 1 110.27 72.67 Example 2 108.46 71.68 Example 3 105.83 68.74 Example 4 93.04 64.20 Example 5 95.41 62.02 Example 6 98.21 66.78 Example 7 100.62 68.31 Example 8 99.84 67.89 Example 9 90.38 63.22 Comparative Example 1 57.88 38.78 Comparative Example 2 67.85 45.46 Comparative Example 3 83.47 54.26 Comparative Example 4 97.90 64.61 Comparative Example 5 88.42 60.97 Comparative Example 6 75.88 50.84

[0085] As shown in Table 1, the mechanical properties of Example 4 are significantly lower than those of Example 1. This is because the surface of the waste rubber that has not been oxidized is relatively rough, and its fusion effect with other components in the system is poor. The waste rubber of Example 1 is soaked in hydrogen peroxide, which can completely remove impurities on the surface of rubber particles, thereby improving the mechanical properties of the material.

[0086] In comparative example 6, no waste rubber is added, and only ceramsite is included in the coarse aggregate, and its mechanical properties are significantly reduced, which shows that waste rubber can replace natural aggregate to improve the toughness and strength of concrete. The mechanical properties of concrete in Examples 5 and 6 are all reduced. In Example 5, the content of waste rubber in the coarse aggregate is too low, resulting in poor support performance of the skeleton; in Example 6, the content of waste rubber in the coarse aggregate is too high, and the fusion degree of rubber with other components in the system is not good. Therefore, the preferred range of coarse aggregate is: the mass ratio of waste rubber to ceramsite is (2~2.5):1, which helps to improve the density and mechanical properties of geopolymer concrete.

[0087] The mechanical properties of the concrete in Examples 7 and 8 are all reduced. The amount of river sand added to the fine aggregate in Example 7 is too low, which leads to a decrease in the anti-permeability of the concrete, reduces the stability of the material, and reduces the mechanical properties; the amount of river sand added to the fine aggregate in Example 8 is too high, indicating that the modified bamboo fiber can effectively improve the impact resistance of the material. Therefore, the preferred range of fine aggregate is: the mass ratio of river sand to modified bamboo fiber is (2.5-3): 1, which can improve the bonding performance of concrete, and good bonding can improve the compressive strength and flexural strength of concrete.

[0088] The sodium sulfate in Example 9 is directly added to the system as a drought-strengthening agent, rather than as an activator for slag, so the mechanical properties of the material are reduced. This is because Example 1 wet-grinds the slag with sodium sulfate, which can reduce the crystallinity of the slag, increase the lattice distortion of the slag structure, produce more amorphous substances, and increase the surface free energy and reactivity of the material, thereby improving the mechanical properties of the material. Comparative Example 3 does not add sodium sulfate, and its mechanical properties are significantly reduced, indicating that sodium sulfate can not only be used as a drought-strengthening agent of the system to improve the mechanical properties of the material, but also can wet-grind and activate the slag to further improve the compressive strength of the material. Moreover, Comparative Examples 4 to 5 use sodium chloride and potassium hydroxide as activators instead of sodium sulfate, but their mechanical properties are significantly reduced compared with Example 1. This is because strong alkali may cause alkali aggregation reaction, and chloride salts can easily cause steel bars to rust, so sodium sulfate is selected as the chemical activator for wet-grinding the slag.

[0089] In Comparative Example 1, no modified bamboo fiber is added, and the fine aggregate contains only river sand, and its mechanical properties are greatly reduced. This is because the river sand can only fill the gaps between the coarse aggregates, while the modified bamboo fiber can not only fill the gaps, but also significantly improve the mechanical properties of the material. In Comparative Example 2, the bamboo fiber is not modified, and its mechanical properties are significantly reduced. This is because after the bamboo fiber is modified with cellulose nanofibers, the adhesion between the bamboo fiber and the concrete matrix can be effectively improved. At the same time, the cellulose nanofibers gradually agglomerate on the surface of the bamboo fiber, which hinders the stress transfer between the interfaces and further improves the mechanical properties of the material.

[0090] In summary, the building material of the present invention uses renewable materials such as bamboo and industrial waste such as slag and waste rubber as raw materials, reduces the use of natural resources and energy, can effectively improve the utilization efficiency of materials, and belongs to green environmental protection materials. Moreover, the geopolymer concrete has the characteristics of good bonding performance, high compressive strength, low carbon emissions, low energy consumption and good durability.

[0091] Finally, it should be noted that the above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the scope of protection of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A green building material, characterized in that: The invention comprises the following raw materials in parts by weight: 200-500 parts of slag, 100-200 parts of diatomaceous earth, 60-150 parts of sodium sulfate, 120-230 parts of alkaline activator, 400-600 parts of coarse aggregate and 200-300 parts of fine aggregate; wherein the coarse aggregate comprises waste rubber and ceramsite; the fine aggregate comprises river sand and modified bamboo fiber; wherein the modified bamboo fiber is cellulose nanofiber modified bamboo fiber; the preparation method of the modified bamboo fiber comprises the following steps: firstly preparing a mixed solution with cellulose nanofiber, grafting resin and coupling agent, then spraying the mixed solution on the surface of bamboo fiber, and drying to obtain the cellulose nanofiber modified bamboo fiber; wherein the mass ratio of grafting resin, coupling agent and cellulose nanofiber is 1:(18-20):(20-60); the mass ratio of the mixed solution to bamboo fiber is (20-60):1; The waste rubber is oxidatively modified waste rubber, and the modification method is to soak the waste rubber in a hydrogen peroxide solution with a mass concentration of (20-30)% for 2-3 hours, then take it out for rinsing, and dry it to obtain the oxidatively modified waste rubber; The preparation method of green building materials comprises the following steps: (1) First, sodium sulfate is added to water to form a slurry, and then the slurry is used to wet-grind the slag to obtain a mixed paste of slag and sodium sulfate; (2) The diatomaceous earth, sodium sulfate and aggregate are stirred and evenly mixed, and then the mixed paste of slag and sodium sulfate and the alkaline activator solution are added and mixed, and then poured into a mold for curing. After demolding, the green building material is obtained.

2. The green building material according to claim 1, characterized in that: The grafted resin is glycidyl methacrylate; the coupling agent is at least one of silane coupling agents KH550, KH570, and KH560.

3. The green building material according to claim 1, characterized in that: The mass ratio of the waste rubber to ceramsite is (2-2.5):1; the particle size of the coarse aggregate is 5-10 mm.

4. The green building material according to claim 1 or 3, characterized in that: The mass ratio of the river sand to the modified bamboo fiber is (2.5-3):1; the particle size of the fine aggregate is 1-4 mm.

5. The green building material according to claim 1, characterized in that: The alkaline activator is sodium hydroxide.

6. The green building material according to claim 1, characterized in that: In step (2) of the method for preparing the green building material, the curing time is 12 to 24 hours.