Cement-free high-strength low-carbon building material containing waste paper fibers and preparation method thereof

Abstract

The invention discloses a low-carbon building material, which is characterized by comprising the following raw materials: river sand or mineral residue as aggregate, cation modified micro-nano waste paper fiber and silica sol. According to the invention, the surface of the waste paper fiber is positively charged through cation modification, and the waste paper fiber and the siliceous aggregate with negatively charged surface generate an electrostatic adsorption effect, so that the fiber-aggregate interface bonding force is remarkably enhanced. The addition of the silica sol further promotes the cross-linking reaction of aggregate-fiber to form a stable network structure. In the preparation process, cement clinker, high-temperature sintering or high-pressure curing are not needed, forming can be performed at normal temperature and normal pressure, resource utilization of waste is achieved, carbon emission is remarkably reduced, and meanwhile cement is replaced.

Description

Technical Field

[0001] This invention relates to the field of building materials technology, specifically to a low-carbon building material and its preparation method, which is formed by electrostatic adsorption, hydrogen bonding and chemical bonding of micro-nano waste paper fibers and negatively charged sand particles or mineral residues under normal temperature and pressure conditions. The micro-nano waste paper fibers are cationic modified micro-nano waste paper fibers. Background Technology

[0002] Traditional cement mortar, as a basic material in the construction industry, has a high energy consumption and large carbon emissions during its production process, which is inconsistent with the current trend of green and low-carbon development. Although there are studies on the preparation of building materials using solid waste such as waste paper fibers, existing technologies suffer from problems such as weak interfacial bonding between fibers and inorganic aggregates, the need for high-temperature and high-pressure molding, and insufficient mechanical properties. The surface of waste paper fibers is rich in negatively charged groups such as hydroxyl groups, which have the same charge as the surface of siliceous aggregates, making it difficult to form stable chemical bonds, thus limiting the development of product strength. Summary of the Invention

[0003] To address the problems existing in the prior art, the present invention aims to provide a low-carbon building material and its preparation method. This method reverses the surface charge of waste paper fibers through cation modification technology and uses electrostatic attraction to achieve a firm bond between micro- and nano-fibers and sand / mineral residues, thereby preparing a low-carbon building material that can replace traditional cement mortar under normal temperature and pressure.

[0004] The technical solution of the present invention is as follows:

[0005] According to one aspect of the present invention, an object of the present invention is to provide a low-carbon building material, characterized in that it is composed of the following raw materials:

[0006] River sand or mineral residue used as aggregate, 50-100 parts by weight;

[0007] Micro-nano waste paper fiber pulp, 5-50 parts by weight, based on oven-dry weight; and

[0008] Silica sol, 3-20 parts by weight on an oven-dry basis.

[0009] Preferably, the low-carbon building material is characterized by being composed of the following raw materials:

[0010] River sand or mineral residue used as aggregate, 60-90 parts by weight;

[0011] Micro-nano waste paper fiber pulp, 8-40 parts by weight, on an oven-dry basis; and

[0012] Silica sol, 5-10 parts by weight on an oven-dry basis.

[0013] More preferably, the low-carbon building material is characterized by being composed of the following raw materials:

[0014] River sand or mineral residue as aggregate, 70 parts by weight;

[0015] Micro-nano waste paper fiber pulp, 20 parts by weight, on an oven-dry basis; and

[0016] Silica sol, 10 parts by weight on an oven-dry basis.

[0017] Preferably, the silica sol is a neutral silica sol with a solid content of 30%, for example, purchased from Guangzhou Fufeng Chemical Technology Co., Ltd.

[0018] Preferably, the low-carbon building material has a compressive strength of 3 MPa to 15 MPa and a flexural strength of 2 MPa to 30 MPa.

[0019] Preferably, the micro / nano waste paper fiber pulp is a cationic modified micro / nano waste paper fiber pulp.

[0020] Preferably, the cationic modified micro / nano waste paper fiber pulp is prepared by the following method:

[0021] (1) Preparation of micro-nano waste paper fiber pulp: After soaking waste paper in water, it is disintegrated in a pulper until there are no pulp lumps. The pulp concentration is adjusted to 1% to 40%, and pulping is carried out at room temperature for 0.5 to 3 hours to obtain micro-nano waste paper fiber pulp.

[0022] (2) Cationic modification: Disperse the micro-nano waste paper fiber pulp containing 1 part by weight of oven dry weight in 30-50 parts by weight of sodium hydroxide solution with a concentration of 2 wt.%, add 0.5-2 parts by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride, and after the reaction is completed, the cationic modified micro-nano waste paper fiber pulp is obtained.

[0023] Preferably, the waste paper in step (1) is selected from one or more of corrugated paper, printing paper, linerboard, kraft paper, paper bag paper, offset paper, etc.

[0024] Preferably, the concentration of the micro-nano waste paper fiber pulp in step (1) is adjusted to 1%-10% by weight.

[0025] Preferably, the mineral residue is at least one of silica fume from a steel plant, fly ash from a power plant, or silica fume from a ferrosilicon plant.

[0026] Preferably, the aggregate particle size range is 50-8000 mesh.

[0027] According to another aspect of the present invention, an object of the present invention is to provide a method for preparing the low-carbon building material, comprising the following steps:

[0028] (1) Weigh each raw material component according to the proportion and mix them evenly at room temperature;

[0029] (2) After filtering the mixture, dry it under normal temperature and pressure to obtain the low carbon board.

[0030] Beneficial effects

[0031] This invention utilizes cationic modification to impart a positive charge to the surface of waste paper fibers, which then electrostatically attracts the negatively charged siliceous aggregates, significantly enhancing the fiber-aggregate interfacial bonding. The addition of silica sol further promotes the cross-linking reaction between the aggregate and fibers, forming a stable network structure. The preparation process requires no cement clinker, high-temperature sintering, or high-pressure curing; it can be molded at room temperature and pressure, achieving resource utilization of waste and a significant reduction in carbon emissions, while simultaneously replacing the use of cement. Attached Figure Description

[0032] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0033] Figure 1 Scanning electron microscope image of the cationic modified micro / nano waste paper fibers prepared in Example 1.

[0034] Figure 2 This is a scanning electron microscope image of a novel low-carbon building material prepared in Example 1 using waste paper fiber as a substitute for cement and river sand.

[0035] Figure 3 This is a scanning electron microscope image of a novel low-carbon building material prepared in Example 4 using waste paper fiber as a substitute for cement and silica fume. Detailed Implementation

[0036] The present invention will now be described in detail. Before proceeding with the description, it should be understood that the terminology used in this specification and the appended claims should not be construed as limited to its general or dictionary meaning, but rather should be interpreted according to the meaning and concept corresponding to the technical aspects of the invention, based on the principle that the inventors are allowed to appropriately define the terms for the best interpretation. Therefore, the description presented herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention. It should be understood that other equivalents or modifications can be obtained from it without departing from the spirit and scope of the invention.

[0037] Preferred embodiments of the present disclosure will be described in detail below with reference to the accompanying drawings. Before description, it should be understood that the terminology used in the specification and appended claims should not be construed as limited to its general and dictionary meaning, but rather should be interpreted based on the principle of allowing the inventors to appropriately define the terminology for the best interpretation, and based on its meaning and concept corresponding to the technical level of the invention. Therefore, the description herein is merely a preferred example for illustrative purposes and is not intended to limit the scope of the invention; thus, it should be understood that other equivalent implementations and modifications can be made without departing from the spirit and scope of the invention.

[0038] In this document, the terms “comprising,” “including,” “having,” “containing,” or any other similar terms are open-ended conjunctions intended to cover non-exclusive inclusions. For example, a composition or article containing a plurality of elements is not limited to those listed herein, but may also include other elements not explicitly listed but typically inherent to the composition or article. Furthermore, unless explicitly stated to the contrary, the term “or” is inclusive, not exclusive. For example, the condition “A or B” is satisfied in any of the following cases: A is true (or exists) and B is false (or does not exist); A is false (or does not exist) and B is true (or exists); A and B are both true (or exist). Moreover, in this document, the terms “comprising,” “including,” “having,” and “containing” should be interpreted as specifically disclosed and simultaneously cover closed or semi-closed conjunctions such as “composed of” and “substantially composed of.”

[0039] In this document, all features or conditions defined in the form of numerical ranges or percentage ranges are for the sake of brevity and convenience only. Accordingly, descriptions of numerical ranges or percentage ranges should be considered as covering and specifically disclosing all possible secondary ranges and individual values ​​within those ranges, particularly integer values. For example, a range description of "1 to 8" should be considered as specifically disclosing all secondary ranges such as 1 to 7, 2 to 8, 2 to 6, 3 to 6, 4 to 8, 3 to 8, etc., particularly secondary ranges defined by all integer values, and should be considered as specifically disclosing individual values ​​within those ranges such as 1, 2, 3, 4, 5, 6, 7, 8, etc. Unless otherwise specified, the foregoing interpretation applies to all content throughout this invention, regardless of its scope.

[0040] If a quantity or other numerical value or parameter is expressed as a range, a preferred range, or a series of upper and lower limits, it should be understood that this document has specifically disclosed all ranges consisting of any upper or preferred value of that range and the lower or preferred value of that range, regardless of whether such ranges are separately disclosed. Furthermore, when a range of numerical values ​​is mentioned herein, unless otherwise stated, the range shall include its endpoints and all integers and fractions within the range.

[0041] In this document, numerical values ​​are to be understood as having a precision with significant digits, provided that the purpose of the invention can be achieved. For example, the number 40.0 should be understood to cover a range from 39.50 to 40.49.

[0042] The following embodiments are merely examples illustrating implementations of the present invention and do not constitute any limitation on the present invention. Those skilled in the art will understand that modifications made without departing from the spirit and concept of the present invention fall within the protection scope of the present invention. Unless otherwise specified, the reagents and instruments used in the following embodiments are commercially available products.

[0043] Preparation Example 1: Preparation of cationic modified micro / nano waste paper fibers

[0044] (1) Preparation of micro-nano waste paper fiber pulp: After soaking waste paper in water, it is disintegrated in a pulper until there are no pulp lumps. The pulp concentration is adjusted to about 2%, and pulping is carried out at room temperature for about 2 hours to obtain micro-nano waste paper fiber pulp.

[0045] (2) Cationic modification: The micro-nano waste paper fiber pulp containing 1 part by weight of solid content is dispersed in 30 parts by weight of sodium hydroxide solution with a concentration of 2 wt.%, and 1 part by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride is added. After the reaction is completed, the cationic modified micro-nano waste paper fiber pulp is obtained.

[0046] Example 1

[0047] Raw material ratio: Take 8 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 1 kg and the addition amount is 10% of the total weight of raw materials), silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg) and 90 kg of water.

[0048] Mixing and Molding: The above raw materials are uniformly mixed at room temperature to ensure that the fibers are fully dispersed in the aggregate. After the mixture is filtered and demolded, it is naturally dried and cured under normal temperature and pressure to obtain a board sample.

[0049] Compressive strength test: The compressive strength of the specimens was determined using an Instron 3345 kN mechanical testing machine via the compression method. The experimental conditions were: maximum load 30 kN, compressive strain 50%, loading rate 5 mm / min, and specimen dimensions of 3 cm × 3 cm × 2 cm. Each group of samples was tested 5 times, and the compressive strength was obtained from the stress-strain curve.

[0050] Flexural strength test: The flexural strength of the specimens was determined using an Instron 3345 kN mechanical testing machine via the three-point bending method. The experimental conditions were: maximum load 30 kN, span 30 mm, loading rate 5 mm / min, and specimen dimensions of 5 cm × 2 cm × 1 cm. Each group of samples was tested 5 times, and the flexural strength was obtained from the stress-strain curve.

[0051] Test results: compressive strength 5 MPa, flexural strength 10 MPa.

[0052] Flame retardant performance test results: Vertical burning test UL-94 standard, V-0 level, critical oxygen index, 100%, cone calorific value in cone calorimetry test 0.30 MJ / Kg (≤2.0), mass loss rate 11% (≤50%), reaching A1 level.

[0053] Example 2

[0054] Except for the following raw material ratios: 8.5 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 0.5 kg and the addition amount is 5% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg), the board samples were prepared in the same manner as in Example 1.

[0055] The performance tests were conducted in the same manner as in Example 1: compressive strength 3 MPa, flexural strength 2 MPa.

[0056] Example 3

[0057] Except for the following raw material ratios: 7.5 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 1.5 kg and the addition amount is 15% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg), the board samples were prepared in the same manner as in Example 1.

[0058] The performance tests were conducted in the same manner as in Example 1: compressive strength 8 MPa, flexural strength 15 MPa.

[0059] Example 4

[0060] Except for the following raw material ratios: 7.0 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 2.0 kg and the addition amount is 20% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg), the board samples were prepared in the same manner as in Example 1.

[0061] The performance tests were conducted in the same manner as in Example 1: compressive strength 10 MPa, flexural strength 20 MPa.

[0062] Example 5

[0063] Except for the following raw material ratios: 6.0 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 3.0 kg and the addition amount is 30% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg), the board samples were prepared in the same manner as in Example 1.

[0064] The performance tests were conducted in the same manner as in Example 1: compressive strength 12 MPa, flexural strength 24 MPa.

[0065] Example 6

[0066] Except for the following raw material ratios: 5.0 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 4.0 kg and the addition amount is 40% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg), the board samples were prepared in the same manner as in Example 1.

[0067] The performance tests were conducted in the same manner as in Example 1: compressive strength 15 MPa, flexural strength 30 MPa.

[0068] Experimental results show that when the fiber content is in the range of 5-40%, the mechanical properties of the product increase with the increase of fiber content.

[0069] Example 7

[0070] Except for the following raw material ratios: 8 kg of ferrosilicon plant silica ash (8000 mesh), the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 1 kg and the addition amount is 10% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1 kg), the board samples were prepared in the same manner as in Example 1.

[0071] Performance tests were conducted in the same manner as in Example 1: the compressive strength of the product reached 9 MPa, and the flexural strength reached 20 MPa. The performance meets the technical requirements for non-load-bearing wall materials.

[0072] Example 8

[0073] Except for the following raw material ratios: 7.5 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 2.0 kg and the addition amount is 20% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 0.5 kg), the board samples were prepared in the same manner as in Example 1.

[0074] The performance was tested in the same manner as in Example 1: compressive strength 6 MPa, flexural strength 13 MPa.

[0075] Example 9

[0076] Except for the following raw material ratios: 7.0 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 2.0 kg and the addition amount is 20% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 1.0 kg), the board samples were prepared in the same manner as in Example 1.

[0077] The performance tests were conducted in the same manner as in Example 1: compressive strength 10 MPa, flexural strength 20 MPa.

[0078] Example 10

[0079] Except for the following raw material ratios: 6.0 kg of 120-150 mesh river sand, the cationic modified micro-nano waste paper fiber pulp prepared in Example 1 (of which the solid content of waste paper fiber is 2.0 kg and the addition amount is 20% of the total weight of raw materials), and silica sol (of which the solid content of silica sol is 30% and the solid content of silica is 2.0 kg), the board samples were prepared in the same manner as in Example 1.

[0080] The performance tests were conducted in the same manner as in Example 1: compressive strength 11 MPa, flexural strength 21 MPa.

[0081] Experimental results show that when the silica sol content is within the range of 5-10%, the mechanical properties of the product improve with increasing silica sol content. The role of silica sol: Silica sol acts as a binder, forming Si-O-Si bonds during material drying and molding, and imparting a certain degree of water resistance to the material. Increasing the silica sol content improves the flexural and compressive strength of the material, as well as its water resistance.

[0082] Comparative Example 1: Effect of Particle Size on Mechanical Properties

[0083] Except that the average particle size of the river sand in the raw materials is 50 mesh, the board samples were prepared in the same manner as in Example 1.

[0084] The performance tests were conducted in the same manner as in Example 1: compressive strength 3 MPa, flexural strength 5 MPa.

[0085] Comparative Example 2: Effect of Particle Size on Mechanical Properties

[0086] Except that the average particle size of the river sand in the raw materials is 300 mesh, the board samples were prepared in the same manner as in Example 1.

[0087] The performance was tested in the same manner as in Example 1: compressive strength 9 MPa, flexural strength 16 MPa.

[0088] Comparative experiments show that when the particle size of river sand increases from 50 mesh to 300 mesh, the mechanical properties continuously improve as the particle size decreases because the change in specific surface area affects the density of the fiber-aggregate contact point.

[0089] This invention achieves interfacial strengthening between fibers and aggregates through charge modification, combined with the cementing effect of silica sol, to prepare low-carbon boards with adjustable properties under ambient temperature and pressure. This technical solution not only avoids the high energy consumption problem of traditional cement-based materials, but also provides an effective way to utilize waste paper and industrial slag, resulting in significant economic and environmental benefits.

[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A low-carbon building material, characterized in that, It is composed of the following raw materials: River sand or mineral residue used as aggregate, 50-100 parts by weight; Micro-nano waste paper fiber pulp, 5-50 parts by weight, based on oven-dry weight; and Silica sol, 3-20 parts by weight on an oven-dry basis.

2. The low-carbon building material according to claim 1, characterized in that, The low-carbon building material is composed of the following raw materials: River sand or mineral residue used as aggregate, 60-90 parts by weight; Micro-nano waste paper fiber pulp, 8-40 parts by weight, on an oven-dry basis; and Silica sol, 5-10 parts by weight on an oven-dry basis.

3. The low-carbon building material according to claim 1, characterized in that, The low-carbon building material is composed of the following raw materials: River sand or mineral residue as aggregate, 70 parts by weight; Micro-nano waste paper fiber pulp, 20 parts by weight, on an oven-dry basis; and Silica sol, 10 parts by weight on an oven-dry basis.

4. The low-carbon building material according to claim 1, characterized in that, The micro-nano waste paper fibers are cationic modified micro-nano waste paper fibers.

5. The low-carbon building material according to claim 1, characterized in that, The silica sol is a neutral silica sol, wherein the silica sol solid content is 30%.

6. The low-carbon building material according to claim 1, characterized in that, The low-carbon building material has a compressive strength of 3 MPa to 15 MPa and a flexural strength of 2 MPa to 30 MPa.

7. The low-carbon building material according to claim 1, characterized in that, The mineral residue is at least one of silica fume from steel plants, fly ash from power plants, or silica fume from ferrosilicon plants.

8. The low-carbon building material according to claim 1, characterized in that, The aggregate, consisting of river sand or mineral residue, has a particle size range of 50-8000 mesh.

9. The low-carbon building material according to claim 4, characterized in that, The cationic modified micro / nano waste paper fibers are prepared by the following method: (1) Preparation of micro-nano waste paper fiber pulp: After soaking waste paper in water, it is disintegrated in a pulper until there are no pulp lumps. The pulp concentration is adjusted to 1% to 40%, and pulping is carried out at room temperature for 0.5 to 3 hours to obtain micro-nano waste paper fiber pulp. (2) Cationic modification: Disperse the micro-nano waste paper fiber pulp containing 1 part by weight of oven dry weight in 30-50 parts by weight of sodium hydroxide solution with a concentration of 2 wt.%, add 0.5-2 parts by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride, and after the reaction is completed, the cationic modified micro-nano waste paper fiber pulp is obtained. Preferably, the slurry concentration in step (1) is adjusted to 1%-10% by weight; Preferably, the waste paper in step (1) is selected from one or more of corrugated paper, printing paper, linerboard, kraft paper, paper bag paper, offset paper, etc.

10. A method for preparing low-carbon building materials according to any one of claims 1 to 9, comprising the following steps: (1) Weigh each raw material component according to the proportion and mix them evenly at room temperature; (2) After filtering the mixture, dry it under normal temperature and pressure to obtain the low carbon board.

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