Special putty for concrete repair and preparation method thereof

Abstract

The invention discloses special putty for concrete repair and a preparation method of the special putty. The problems that traditional putty cannot be thickly coated, is poor in adhesive force and is not durable are solved. The concrete comprises the following raw materials: sodium silicate, white cement, silica fume, ground calcium carbonate, talcum powder, cellulose, a water reducing agent, a rheological additive, a surface smoothing agent and hydrophobic rubber powder. The hydrophobic rubber powder comprises the following raw materials: n-octyl trichlorosilane, water and rubber powder. The preparation method comprises the following steps: adding an organic solvent into a reaction kettle, then adding n-octyltrichlorosilane, starting stirring, adding water, evaporating the product to dryness at normal temperature, and mixing the obtained powder with rubber powder to obtain the hydrophobic rubber powder. And sequentially adding silica fume, sodium silicate, talcum powder, cellulose, white cement and heavy calcium carbonate, stirring, adding a water reducing agent, hydrophobic rubber powder, a rheological additive and a surface smoothing agent, and stirring again to obtain the special putty for concrete repair. The special putty is excellent in performance, small in water addition amount, easy to construct, high in drying speed and good in water resistance and alkali resistance.

Description

Technical Field

[0001] The invention belongs to the field of substrate repair putty, and particularly relates to a special putty for concrete repair and a preparation method thereof. Background Art

[0002] Conventional concrete corrodes after years of service, becoming loose and flaking. Traditional repairs use plaster or mortar for larger pits and putty for smaller cracks or rough surfaces. However, these repair materials have poor adhesion and corrosion resistance to concrete structures, and will begin to flake off after a short period of use, especially in water-soaked areas. Plaster and mortar repairs also leave a rough surface, significantly different from the concrete's pre-service appearance. Epoxy mortar has poor weather resistance and often becomes powdery after exposure to ultraviolet light, resulting in decreased performance. Putty repairs should not be too thick, as this can easily crack and fail to meet repair requirements. Summary of the Invention

[0003] The invention aims to provide a special putty for concrete repair, so as to solve the problems that traditional putty cannot be applied thickly, has poor adhesion and is not durable.

[0004] Another object of the present invention is to provide a method for preparing a special putty for concrete repair.

[0005] The technical solution of the present invention is: (one) A special putty for concrete repair, characterized by comprising the following raw materials: sodium silicate, white cement, silica fume, heavy calcium carbonate, talc, cellulose, water reducing agent, rheological additive, surface slip agent, and hydrophobic rubber powder; The hydrophobic rubber powder comprises the following raw materials: n-octyltrichlorosilane, deionized water, and rubber powder; The weight proportions of the above raw materials are as follows: 20-25 parts of sodium silicate, 10-15 parts of white cement, 30-35 parts of silica fume, 13-23 parts of heavy calcium carbonate, 5-8 parts of talc, 1-2 parts of cellulose, 0.5-1 part of water reducer, 0.5-1 part of rheological additive, 0.3-0.8 part of surface slip agent, 1-3 parts of n-octyltrichlorosilane, 0.01-0.03 parts of deionized water, and 2-3 parts of rubber powder.

[0006] As a further improvement of the present invention, the rubber powder adopts JF-B201 produced by Gansu Baolu New Material Technology Co., Ltd. or 303 produced by Lanzhou Kent Chemical Co., Ltd.

[0007] As a further improvement of the present invention, the sodium silicate adopts the superior industrial grade sodium silicate of Jinan Xinguan Chemical Products Co., Ltd. or the superior grade sodium silicate of Shanxi Chengxin Hongsheng Trading Co., Ltd.

[0008] As a further improvement of the present invention, the water reducing agent adopts a silicon-containing water reducing agent. (two) A method for preparing a special putty for concrete repair, characterized by comprising the following steps: A. Preparation of hydrophobic rubber powder: Add an appropriate amount of organic solvent to a reactor, tightly cover it, add n-octyltrichlorosilane, and then start stirring. Use a peristaltic pump to slowly and evenly add deionized water while stirring at room temperature. The water addition time is between 60-90 minutes. After the reaction is completed, evaporate the product to dryness at room temperature using a rotary evaporator. Mix the obtained powder with the rubber powder to obtain the hydrophobic rubber powder. Connect a sodium carbonate solution with a mass fraction of 10-15% to the tail of the reactor as an exhaust gas absorption device. B. Mixing of putty powder: Add silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate into the mixing tank in this order, start the mixer and stir. Slowly add water reducer, hydrophobic glue powder, rheological additive and surface slip agent while stirring, and continue stirring to obtain putty for concrete repair.

[0010] The reaction mechanism of hydrophobic rubber powder is as follows: n-Octyltrichlorosilane (C8H 17 The reaction of Cl3Si) with water is divided into two steps: hydrolysis and condensation. Its specific reaction mechanism can be decomposed into the following steps: (1) The first step of hydrolysis: The nucleophilic oxygen atom in the water molecule attacks the silicon atom, replacing a chlorine atom, forming a monohydroxyl substitution intermediate and releasing hydrogen chloride: C8H 17 Cl3Si+H2O→C8H 17 SiCl2OH+HCl (2) Second step hydrolysis: The second water molecule continues to attack the silicon atom, replacing another chlorine atom to generate a dihydroxy substituted intermediate: C8H 17 SiCl2OH+H2O→C8H 17 SiCl(OH)2+HCl (3) The third step of hydrolysis: The third water molecule replaces the last chlorine atom to form unstable silanol (octylsilanol): C8H 17 SiCl(OH)2+H2O→C8H 17 Si(OH)3+HCl (4) Condensation reaction forms Si-O-Si bond, and the generated silanol (C8H 17 Si(OH)3) is unstable, and the silanol groups (Si-OH) on adjacent molecules are prone to dehydration condensation reactions to form dimers or oligomers containing Si-O-Si bonds: C8H 17 Si(OH)3→C8H 17Si(OH)2-O-Si(OH)2C8H 17 +H2O This process then continues with further polycondensation, ultimately forming a three-dimensional network polymer cross-linked by siloxane bonds (-Si-O-Si-). This product is then dried by rotary evaporation and mixed with rubber powder to produce a hydrophobic rubber powder.

[0011] As a further improvement of the present invention, in step A, the organic solvent is n-heptane.

[0012] As a further improvement of the present invention, in step A, the stirring speed is 50-60 r / min.

[0013] As a further improvement of the present invention, in step A, the mixture is stirred for 10-15 minutes after adding water.

[0014] As a further improvement of the present invention, in step B, the stirring speed is 30-40 r / min.

[0015] As a further improvement of the present invention, in step B, the stirring time after adding silica fume, sodium silicate, talc, cellulose, white cement, and heavy calcium carbonate is 10-15 minutes, and the stirring time after adding the water reducer, hydrophobic rubber powder, rheological additive, and surface slip agent is 30-45 minutes.

[0016] The beneficial effects of the present invention are: 1. The hydrophobic rubber powder in the special putty of this invention is a key component. This hydrophobic rubber powder utilizes physical and chemical effects to orient long alkyl chains on the surface of the putty layer, significantly increasing the contact angle of water on its surface, thereby effectively improving the putty layer's water resistance. This addresses the durability issues associated with traditional putties due to water absorption, while also enhancing corrosion resistance. The innovative design of this hydrophobic rubber powder is reflected in the following aspects: ① It utilizes a Si-O-Si rigid structure to ensure durability. After physical mixing with elastic rubber powder, it achieves a synergistic combination of rigidity and flexibility during the construction and water curing process, optimizing the putty layer's crack resistance. ② It uses silane oligomers to create a hydrophobic structure that cross-links with sodium silicate, the concrete base, and other putty components, forming a stable silicon-based three-dimensional network structure that effectively prevents shedding and pulverization. ③ Through the dual mechanism of surface hydrophobic modification and internal cross-linking reinforcement, the material's overall corrosion resistance and long-term durability are significantly enhanced. The various components of this hydrophobic rubber powder achieve synergistic optimization of hydrophobicity and mechanical properties, providing a superior surface treatment solution for architectural decorative materials.

[0017] 2. The special putty of the present invention uses silica fume as the main component. Silica fume is an ultrafine siliceous powder material formed by the rapid oxidation and condensation of SiO2 and Si gas in the air. It is a large amount of industrial solid waste generated in the process of smelting ferrosilicon alloys and industrial silicon. The use of silica fume not only achieves high-quality utilization of industrial solid waste and significantly reduces material costs, but also complies with national environmental protection policy requirements. Silica fume has a large specific surface area and extremely high activity. Its tiny spherical particle structure can play an excellent lubricating role, making the construction process smoother and more convenient; at the same time, silica fume can significantly improve the anti-seepage, anti-corrosion, impact resistance and wear resistance of the putty layer. During the material curing process, silica fume can undergo a cross-linking and curing reaction with sodium silicate or the base material, effectively avoiding the powder falling phenomenon and greatly improving the adhesion ability of the material.

[0018] 3. The special putty of the present invention uses sodium silicate as the key bonding component, which can undergo a cross-linking reaction with the substrate, significantly improving the adhesion of the putty layer. It is also used in combination with high-hardness silicate white cement to form a composite system that is both rigid and flexible, thereby achieving multiple excellent properties such as high hardness, crack-free, and strong adhesion. Through the synergistic effect of the chemical bonding effect of sodium silicate and the physical reinforcement of white cement, the putty product maintains excellent construction performance while obtaining better mechanical properties and durability.

[0019] 4. The special putty of this invention utilizes a rheological additive as a key functional component. By regulating rheological properties, it significantly improves the putty layer's anti-sagging properties, ensuring easy application. This rheological additive synergizes with components such as sodium silicate, hydrophobic rubber powder, and silica fume to construct a stable, three-dimensional silicon-based network structure, significantly enhancing the adhesion of the putty layer to the substrate and significantly improving the overall durability of the material. The use of this rheological additive achieves an optimal balance between application performance and end-use performance, enabling the putty product to achieve more reliable performance and quality improvements while maintaining excellent application properties.

[0020] 5. The special putty of the present invention uses a surface slipper to play multiple functions such as moisturizing, lubricating, thickening, and slipping. It works together with hydrophobic rubber powder, cellulose, and rheological additives to achieve the purpose of easy construction, anti-sulfur hanging, and hydrophobic and smooth surface.

[0021] 6. The special putty of the present invention uses a water reducer, which is not only beneficial to the putty mixing process, but also the water reducer is a silicon-containing material, which combines with sodium silicate and silica fume to improve the adhesion of the putty layer, avoid powdering, and improve the anti-corrosion performance.

[0022] 7. The special putty of the present invention has excellent performance, small water addition amount, easy construction, fast drying speed, no peeling or shedding after 5 years of outdoor use, water resistance and alkali resistance are more than doubled compared with the standard, and has certain anti-corrosion performance.

[0023] 8. The sodium silicate, white cement, silica fume, water reducer, rheological additive, surface slip agent and hydrophobic rubber powder in the present invention cooperate with each other in cross-linking reaction and work together. Since it is not a traditional film-forming drying and curing, but a cross-linking reaction is used for curing, the internal moisture can escape in the form of water vapor before and after drying and curing, and cracks and the like will not appear during the thick coating construction of the putty layer, and the thickest part can reach more than 2 cm. The Si-O-Si spatial structure formed by the reaction gradually embeds the filler and can react and cross-link with the concrete substrate structure, greatly improving the adhesion of the putty layer and avoiding powdering. The Si-O bond energy is large, and the water resistance, alkali resistance and durability are excellent, and the anti-corrosion performance is qualitatively improved compared to ordinary putty.

[0024] 9. The hydrophobic rubber powder prepared by the method of the present invention has a controllable molecular weight, a moderate degree of reaction, and a significant effect after use. It can balance the two contradictory aspects of waterproofing and uniform dispersion of rubber powder according to the requirements of the invention; the dry powder materials are added in sequence according to the density relationship during the mixing process, and the mixing is more uniform, thereby maximizing the protective effect of the material. DETAILED DESCRIPTION

[0025] The present invention is further described in detail below with reference to specific embodiments.

[0026] In the following examples and comparative examples, sodium silicate was purchased from Jinan Xinguan Chemical Products Co., Ltd. for high-quality industrial-grade sodium silicate; white cement was purchased from Shenyang Xinmeijia Building Decoration Materials Co., Ltd.; silica fume was purchased from Gansu Sanyuan Silicon Materials Co., Ltd.; heavy calcium carbonate was purchased from Lingshou Yongshun Mineral Products Processing Plant; talc was purchased from Penglai Yongfengda Ultrafine Talc Factory, cellulose was purchased from Dacheng Yibo Chemical Co., Ltd., water reducer was purchased from Jiangsu Subote New Materials Co., Ltd. for PCA-400P, rheological additive was purchased from Zhejiang Fenghong New Materials Co., Ltd. for SMY-LT, surface slipper was purchased from Langfang Donghao Environmental Protection Technology Co., Ltd., n-octyltrichlorosilane was purchased from McLean, deionized water was homemade, and rubber powder was purchased from Gansu Baolu New Materials Technology Co., Ltd.

[0027] The weight proportions of the various embodiments are shown in Table 1.

[0028]

[0029] Example 1 A method for preparing a special putty for concrete repair comprises the following steps: A. Preparation of hydrophobic rubber powder: Add an appropriate amount of n-heptane to a reactor, cover tightly, add n-octyltrichlorosilane, and then start stirring at a speed of 50 r / min. Use a peristaltic pump to slowly and evenly add deionized water while stirring at room temperature. Connect a 10% mass concentration sodium carbonate solution to the rear of the reactor as a tail gas absorber. Add water over 60 minutes, then stir for another 15 minutes before stopping stirring. Evaporate the product to dryness at room temperature using a rotary evaporator. Mix the resulting powder with rubber powder to obtain hydrophobic rubber powder. B. Mixing of putty powder: Add silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate into the mixing tank in this order, start the mixer and stir at 30r / min for 15 minutes, slowly add water reducer, hydrophobic glue powder, rheological additive and surface slip agent while stirring, and then stir for 45 minutes to obtain the putty for concrete repair.

[0030] The role of n-heptane in the reaction process is reaction solvent, and the amount of n-octyltrichlorosilane used is generally 2-3 times, which can ensure the normal progress of the reaction.

[0031] Example 2 A method for preparing a special putty for concrete repair comprises the following steps: A. Preparation of hydrophobic rubber powder: Add an appropriate amount of n-heptane to a reactor, cover tightly, add n-octyltrichlorosilane, and then start stirring at a speed of 60 r / min. Use a peristaltic pump to slowly and evenly add deionized water while stirring at room temperature. Connect a 15% mass concentration sodium carbonate solution to the rear of the reactor as a tail gas absorber. Add water over 90 minutes, then stir for another 10 minutes before stopping stirring. Evaporate the product to dryness at room temperature using a rotary evaporator. Mix the resulting powder with rubber powder to obtain hydrophobic rubber powder. B. Mixing of putty powder: Add silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate into the mixing tank in this order, start the mixer and stir at 40r / min for 10 minutes, slowly add water reducer, hydrophobic glue powder, rheological additive and surface slip agent while stirring, and then stir for 30 minutes to obtain the putty for concrete repair.

[0032] Example 3 A method for preparing a special putty for concrete repair comprises the following steps: A. Preparation of hydrophobic rubber powder: Add an appropriate amount of n-heptane to a reactor, cover tightly, add n-octyltrichlorosilane, and then start stirring at a speed of 55 r / min. Use a peristaltic pump to slowly and evenly add deionized water while stirring at room temperature. Connect a 13% mass concentration sodium carbonate solution to the rear of the reactor as a tail gas absorber. Add water over 80 minutes, then stir for another 13 minutes before stopping stirring. Evaporate the product to dryness using a rotary evaporator at room temperature. Mix the resulting powder with rubber powder to obtain hydrophobic rubber powder. B. Mixing of putty powder: Add silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate into the mixing tank in this order, start the mixer and stir at 35r / min for 13 minutes, slowly add water reducer, hydrophobic glue powder, rheological additive and surface slip agent while stirring, and then stir for 40 minutes to obtain the putty for concrete repair.

[0033] Comparative Example 1 In this comparative example, no hydrophobic rubber powder was prepared, and commercially available rubber powder (purchased from Gansu Baolu New Material Technology Co., Ltd.) was directly used.

[0034] Mixing of putty powder: Add silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate into the mixing tank in this order, start the mixer and stir at 30r / min for 15 minutes, slowly add water reducer, glue powder, rheological additive and surface slip agent while stirring, and then stir for 45 minutes to obtain special putty for concrete repair.

[0035] The performance test of the special putty prepared in Examples 1-3 is shown in Table 2.

[0036]

[0037] The bonding strength, water resistance, alkali resistance and other properties of the special putty for concrete repair of the present invention are significantly improved, and the water absorption is far lower than the standard requirement, indicating that the anti-corrosion ability is excellent.

Claims

1. A special putty for concrete repair, characterized in that Including the following raw materials: sodium silicate, white cement, silica fume, heavy calcium carbonate, talc, cellulose, water reducer, rheological additive, surface slip agent, hydrophobic rubber powder; The hydrophobic rubber powder comprises the following raw materials: n-octyltrichlorosilane, deionized water, and rubber powder; The weight proportions of the above raw materials are as follows: 20-25 parts of sodium silicate, 10-15 parts of white cement, 30-35 parts of silica fume, 13-23 parts of heavy calcium carbonate, 5-8 parts of talc, 1-2 parts of cellulose, 0.5-1 part of water reducer, 0.5-1 part of rheological additive, 0.3-0.8 part of surface slip agent, 1-3 parts of n-octyltrichlorosilane, 0.01-0.03 parts of deionized water, and 2-3 parts of rubber powder.

2. The special putty for concrete repair according to claim 1, characterized in that: The rubber powder is JF-B201 produced by Gansu Baolu New Material Technology Co., Ltd. or 303 produced by Lanzhou Kent Chemical Co., Ltd.

3. The special putty for concrete repair according to claim 1, characterized in that: The sodium silicate is the high-quality industrial grade sodium silicate produced by Jinan Xinguan Chemical Products Co., Ltd. or the high-quality sodium silicate produced by Shanxi Chengxin Hongsheng Trading Co., Ltd.

4. The special putty for concrete repair according to claim 1, characterized in that: The water reducing agent is a silicon-containing water reducing agent.

5. A method for preparing a special putty for concrete repair according to any one of claims 1 to 4, characterized in that The following steps are involved: A. Preparation of hydrophobic rubber powder: Add an organic solvent to a reactor, then add n-octyltrichlorosilane, and then start stirring. Add deionized water under stirring at room temperature. After the reaction is completed, evaporate the product to dryness at room temperature. Mix the obtained powder with rubber powder to obtain hydrophobic rubber powder; B. Mixing of putty powder: Add silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate into the mixing tank in this order, start the mixer and stir, add water reducer, hydrophobic rubber powder, rheological additive and surface slip agent while stirring, and continue stirring to obtain putty for concrete repair.

6. The method for preparing a special putty for concrete repair according to claim 5, characterized in that: In step A, n-heptane is used as the organic solvent.

7. The method for preparing a special putty for concrete repair according to claim 5, characterized in that: In step A, the stirring speed is 50-60 r / min.

8. The method for preparing a special putty for concrete repair according to claim 7, characterized in that: In step A, add water and stir for 10-15 minutes.

9. The method for preparing a special putty for concrete repair according to claim 5, characterized in that: In step B, the stirring speed is 30-40 r / min.

10. The method for preparing a special putty for concrete repair according to claim 9, characterized in that: In step B, the stirring time is 10-15 minutes after adding silica fume, sodium silicate, talc, cellulose, white cement and heavy calcium carbonate, and the stirring time is 30-45 minutes after adding water reducer, hydrophobic rubber powder, rheological additive and surface slip agent.

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