Lightweight cement-based reinforcing material and preparation method thereof

Abstract

The invention relates to the field of building materials, in particular to a light cement-based reinforcing material and a preparation method thereof. Sodium hydroxide and sodium silicate are mixed with a foaming agent to prepare a bubble group, and cement, mineral powder, cellulose ether, rubber powder, a water reducing agent, machine-made sand and the bubble group are proportioned according to a certain proportion to prepare the concrete. Alkaline treatment is carried out on the injected bubble group, after foaming is carried out through a foaming machine, the surface of the bubble group is an alkali-activated solution, the alkali-activated solution and a large amount of mineral powder can be subjected to an alkali-activated reaction, and a C-S-H gel hard shell is formed on the surface of the bubble in advance before hydration and condensation of a mixture, so that stress dispersion is facilitated; the organic fiber, the cellulose ether and the rubber powder are added, so that the adhesive property and the fracture resistance of the cement-based reinforcing material are improved, and the cement-based reinforcing material which is light and has strength is obtained.

Description

Technical Field

[0001] The invention relates to the field of building materials, and in particular to a lightweight cement-based reinforcement material and a preparation method thereof. Background Art

[0002] Reinforcement materials mainly use the material's flexural and bending strength to reinforce columns, walls, and even masonry structures. When reinforcement materials are poured or covered on the outside, they can improve the seismic and shear resistance of old building walls. However, in the renovation of old houses, the reinforcement materials currently on the market often show problems such as excessive strength and excessive self-weight, which makes construction difficult.

[0003] The main work of reinforcement materials is to focus on repair and reinforcement work, and their physical performance indicators generally only need to meet the indicator requirements of the repair plan. Therefore, in order to pursue strength, existing reinforcement materials often use extremely low water-cement ratios, which leads to the fact that existing reinforcement materials generally have extremely high density, greatly increasing the load of the building. Secondly, reinforcement materials are mainly constructed by three methods: plastering, pouring, and spraying. If lightweight aggregates are used to reduce the bulk density of cement-based reinforcement materials, it will be difficult to smooth or the slurry will separate, and reducing the density will have a great impact on the strength of the reinforcement materials.

[0004] In cement-based materials, the presence of alkali has a significant impact on the hydration process and the microstructure of the product. In existing technologies, most of them adopt the method of directly adding alkali components to cement paste, which may cause the hydration products to grow into the bubbles, destroy the round shell structure of the pores, and cause the volume stability and durability of cement-based materials to decrease, and even cause cracking.

[0005] Therefore, how to add alkali into cement-based materials to obtain a reinforced material that is both lightweight and strong is a technical problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] In order to solve the problem of how to add alkali to cement-based materials to obtain a lightweight and strong reinforcement material, the present invention provides a lightweight cement-based reinforcement material, which comprises 500-600 parts of cement, 500-600 parts of mineral powder, 320-340 parts of water, 8-12 parts of water reducer, 750-850 parts of machine-made sand, 5-15 parts of organic fiber, 1-3 parts of cellulose ether, 3-5 parts of rubber powder, and 8-12 parts of bubble group by weight; The preparation method of the bubble group is: A mixture of sodium silicate and sodium hydroxide, a foaming agent and water are added into a container to prepare an alkaline foaming liquid, and the alkaline foaming liquid is foamed by a foaming machine to obtain a bubble group.

[0007] On the basis of the above scheme, further, the mass ratio of the sodium silicate and sodium hydroxide mixture, the foaming agent and water is 50-60:1:30; in the sodium silicate and sodium hydroxide mixture, the mass ratio of sodium silicate and sodium hydroxide is 10:1; and the dilution ratio of the foaming agent is 30-60 times.

[0008] On the basis of the above scheme, further, the density of the bubble group is 75-85 kg / m 3 .

[0009] Preferably, the density of the bubble group is 80 kg / m 3 .

[0010] On the basis of the above scheme, further, the foaming agent is a non-protein foaming agent, the sedimentation distance is 10-20 mm, and the water secretion volume is 145-155 mL.

[0011] Preferably, the settling distance of the foaming agent is 15 mm and the water exudation is 150 mL.

[0012] On the basis of the above scheme, further, the cement is silicate cement with a strength grade not lower than P·O 42.5, and the mineral powder grade is not lower than S95.

[0013] On the basis of the above scheme, further, the water reducer is a polycarboxylic acid high-efficiency water reducer, and the water reduction rate is not less than 14%.

[0014] On the basis of the above scheme, further, the machine-made sand is medium sand, and its fineness modulus is 2.9.

[0015] On the basis of the above scheme, further, the cellulose ether is a cellulose ether with a viscosity of 100,000; and the rubber powder is a redispersible latex powder.

[0016] On the basis of the above solution, further, the organic fiber is a polypropylene fiber with a length of 6-15 mm, a diameter of 30-50 μm, and a tensile strength of not less than 500 MPa.

[0017] The present invention also provides a method for preparing the lightweight cement-based reinforcement material as described above, comprising the following steps: S1. Weigh cement, mineral powder, cellulose ether, organic fiber, rubber powder and machine-made sand according to proportion and mix them evenly to obtain a mixture A; S2, adding water and water reducing agent weighed in proportion to mixture A, stirring and mixing evenly to obtain mixture B; S3. After weighing the bubble group, add it into the mixture B to obtain the lightweight cement-based reinforcement material.

[0018] The technical solution of the present invention has the following principles and technical effects: The lightweight cement-based reinforcement material provided by the present invention has an alkali-activated solution on the surface of the bubble group after foaming by a foaming machine, which can react with a large amount of mineral powder to activate alkali, and forms a CSH gel hard shell on the bubble surface in advance before the mixture is hydrated and condensed, which is equivalent to converting the bubble into a hard lightweight aggregate, which is helpful for stress dispersion. The present invention reduces the slurry bulk density of the cement-based reinforcement material through the foaming process, and improves the strength of the bubble itself by pre-treating the foaming liquid. In addition, the addition of organic fiber, cellulose ether and rubber powder improves the bonding performance and flexural resistance of the cement-based reinforcement material, so as to form a lightweight cement-based reinforcement material with the compressive and flexural strength of medium- and high-strength concrete. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be described clearly and completely below. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention also provides the following embodiments and comparative examples: Example 1 Preparation method of bubble clusters: In parts by weight, 60 parts of sodium silicate, 6 parts of sodium hydroxide, 1 part of foaming agent and 30 parts of water are prepared into an alkaline foaming liquid; the alkaline foaming liquid is foamed by a foaming machine to obtain a bubble group; the dilution ratio of the foaming agent is 30 times.

[0021] The preparation method of lightweight cement-based reinforcement material comprises the following specific steps: S1, weigh 5.5 kg of cement, 5.5 kg of mineral powder, 8 kg of machine-made sand, 100 g of organic fiber, 20 g of cellulose ether, and 40 g of rubber powder according to proportion, mix them evenly, and obtain a mixture A; S2, adding 3.3 kg of water and 100 g of water reducing agent to mixture A, stirring for 3 min and mixing evenly to obtain mixture B; S3, weighing 100 g of the bubble group, and adding it to the mixture B to obtain the lightweight cement-based reinforcement material; The density of the bubble group is 80 kg / m 3 ; The foaming agent is a non-protein foaming agent with a settling distance of 15 mm and a water secretion volume of 150 mL.

[0022] The cement is PO 42.5 ordinary Portland cement; the mineral powder is S95 mineral powder; The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent with a water reducing rate of 15%; The machine-made sand is medium sand with a fineness modulus of 2.9; The organic fiber is a polypropylene fiber with a length of 6-12 mm, a diameter of 30 μm, and a tensile strength of 800 MPa; the viscosity of the cellulose ether is 200,000; and the rubber powder is a redispersible latex powder.

[0023] Example 2 In parts by weight, 40 parts of sodium silicate, 4 parts of sodium hydroxide, 1 part of foaming agent and 30 parts of water are prepared into an alkaline foaming liquid; the alkaline foaming liquid is foamed by a foaming machine to obtain a bubble group; the dilution ratio of the foaming agent is 30 times.

[0024] The preparation method of lightweight cement-based reinforcement material comprises the following specific steps: S1, weigh 5kg of cement, 5kg of mineral powder, 7.5kg of machine-made sand, 50g of organic fiber, 10g of cellulose ether, and 30g of rubber powder according to proportion, mix them evenly, and obtain a mixture A; S2, add 3.2 kg of water and 80 g of water reducing agent to mixture A, stir for 3 min and mix well to obtain mixture B; S3, weighing 80 g of the bubble group and adding it to the mixture B to obtain the lightweight cement-based reinforcement material; The cement is PO 42.5 ordinary Portland cement; the mineral powder is S95 mineral powder; The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent with a water reducing rate of 15%; The machine-made sand is medium sand with a fineness modulus of 2.9; The organic fiber is a polypropylene fiber with a length of 6-12 mm, a diameter of 30 μm, and a tensile strength of 800 MPa; the viscosity of the cellulose ether is 200,000; and the rubber powder is a redispersible latex powder.

[0025] Example 3 In parts by weight, 60 parts of sodium silicate, 6 parts of sodium hydroxide, 1 part of foaming agent and 30 parts of water are prepared into an alkaline foaming liquid; the alkaline foaming liquid is foamed by a foaming machine to obtain a bubble group; the dilution ratio of the foaming agent is 30 times.

[0026] The preparation method of lightweight cement-based reinforcement material comprises the following specific steps: S1, weigh 6kg of cement, 6kg of mineral powder, 8.5kg of machine-made sand, 120g of organic fiber, 30g of cellulose ether, and 50g of rubber powder according to proportion, mix them evenly, and obtain a mixture A; S2, adding 3.4 kg of water and 120 g of water reducing agent to mixture A, stirring for 3 min and mixing evenly to obtain mixture B; S3, weighing 120 g of the bubble group and adding it to the mixture B to obtain the lightweight cement-based reinforcement material; The cement is PO 42.5 ordinary Portland cement; the mineral powder is S95 mineral powder; The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent with a water reducing rate of 15%; The machine-made sand is medium sand with a fineness modulus of 2.9; The organic fiber is a polypropylene fiber with a length of 6-12 mm, a diameter of 30 μm, and a tensile strength of 800 MPa; the viscosity of the cellulose ether is 200,000; and the rubber powder is a redispersible latex powder.

[0027] Comparative Example 1 The difference between Comparative Example 1 and Example 1 is that during the preparation of the bubble group in Comparative Example 1, no sodium silicate and sodium hydroxide were added, and the remaining component proportions, raw materials and operation process were the same as those in Example 1.

[0028] Comparative Example 2 The difference between Comparative Example 2 and Example 1 is that in the components of Comparative Example 2, no organic fiber, cellulose ether and rubber powder are added, and the proportions of other components, raw materials and operation process are the same as those of Example 1.

[0029] Comparative Example 3 The difference between Comparative Example 3 and Example 1 is that in the components of Comparative Example 3, the added amount of the bubble group is 500 g, and the proportions of other components, raw materials and operating procedures are the same as those of Example 1.

[0030] Comparative Example 4 The difference between Comparative Example 4 and Example 1 is that in the components of Comparative Example 4, no bubble group, cellulose ether and rubber powder are added, and the proportions of other components, raw materials and operation process are the same as those of Example 1.

[0031] Performance Testing The dry density of the reinforcement materials prepared in the above examples and comparative examples was tested according to JG / T226-2011 "Foamed Concrete", and the rest was tested according to the method of GB / T 50081 "Standard for Test Methods of Physical Properties of Concrete". The test results are shown in Table 1.

[0032] Table 1

[0033] As can be seen from Table 1, compared with Comparative Example 1, the present invention has better compressive strength under the influence of alkaline treatment of bubble groups; compared with Comparative Example 2, the lightweight cement-based reinforcement material provided by the present invention has better flexural strength under the influence of organic fibers and better splitting tensile strength under the influence of cellulose ether and rubber powder compared with lightweight concrete with similar density; compared with Comparative Example 3, compared with lighter thermal insulation materials, the lightweight cement-based reinforcement material configured by the present invention has better compressive resistance, flexural strength and splitting tensile strength; compared with Comparative Example 4, the lightweight cement-based reinforcement material provided by the present invention has a lighter dry density under the influence of bubble groups and has a higher splitting tensile strength under the influence of cellulose ether and rubber powder compared with high ductility concrete materials with similar functions; the present invention can fully meet the demand for low-weight reinforcement materials under conventional strength requirements.

[0034] In summary, the present invention reduces the slurry bulk density of cement-based reinforcement materials through the foaming process, and improves the strength of the bubbles themselves by pre-treating the foaming liquid, thereby forming a lightweight cement-based reinforcement material with the compressive and flexural strength of medium- and high-strength concrete.

[0035] Although the terms such as bubble group, alkaline foaming liquid, foaming machine and water reducing agent are used more frequently in this article, the possibility of using other terms is not excluded. These terms are used only to more conveniently describe and explain the essence of the present invention; interpreting them as any additional restrictions is contrary to the spirit of the present invention.

[0036] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A lightweight cement-based reinforcement material, characterized in that: By weight, it includes 500-600 parts of cement, 500-600 parts of mineral powder, 320-340 parts of water, 8-12 parts of water reducing agent, 750-850 parts of machine-made sand, 5-15 parts of organic fiber, 1-3 parts of cellulose ether, 3-5 parts of rubber powder, and 8-12 parts of bubble group; The preparation method of the bubble group is: A mixture of sodium silicate and sodium hydroxide, a foaming agent and water are added into a container to prepare an alkaline foaming liquid, and the alkaline foaming liquid is foamed by a foaming machine to obtain a bubble group.

2. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The mass ratio of the sodium silicate and sodium hydroxide mixture, the foaming agent and water is 50-60:1:30; in the sodium silicate and sodium hydroxide mixture, the mass ratio of sodium silicate to sodium hydroxide is 10:1; and the dilution ratio of the foaming agent is 30-60 times.

3. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The density of the bubble group is 75-85 kg / m 3 .

4. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The foaming agent is a non-protein foaming agent with a settling distance of 10-20 mm and a water secretion volume of 145-155 mL.

5. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The cement is silicate cement with a strength grade not lower than P·O 42.5, and the mineral powder grade is not lower than S95.

6. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The water reducing agent is a polycarboxylic acid high-efficiency water reducing agent, and the water reducing rate is not less than 14%.

7. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The machine-made sand is medium sand, and its fineness modulus is 2.

9.

8. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The cellulose ether is a cellulose ether with a viscosity of 100,000; and the rubber powder is a redispersible latex powder.

9. The lightweight cement-based reinforcement material according to claim 1, characterized in that: The organic fiber is a polypropylene fiber with a length of 6-15 mm, a diameter of 30-50 μm, and a tensile strength of not less than 500 MPa.

10. A method for preparing a lightweight cement-based reinforcement material according to any one of claims 1 to 9, characterized in that: The steps include: S1. Weigh cement, mineral powder, cellulose ether, organic fiber, rubber powder and machine-made sand according to proportion and mix them evenly to obtain a mixture A; S2, adding water and water reducing agent weighed in proportion to mixture A, stirring and mixing evenly to obtain mixture B; S3. After weighing the bubble group, add it into the mixture B to obtain the lightweight cement-based reinforcement material.

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