Preparation method and application of cement-based composite phase change grouting material

Abstract

The invention belongs to the technical field of grouting materials, and particularly relates to a preparation method and application of a cement-based composite phase change grouting material, and the cement-based composite phase change grouting material is prepared from the following raw material components: Portland cement, gravel aggregate, a fiber reinforced material, a water reducing agent, a phase change material, fly ash and water; the preparation method comprises the following steps: 1, respectively weighing the raw material components, and preparing all the raw material components; and 2, adding the raw materials into a mixer, starting stirring, controlling the stirring speed to be 500-1000r / min, mechanically stirring and uniformly mixing, and discharging to obtain the cement-based composite phase change grouting material. According to the invention, the compatibility between the phase change material and the cement base material is effectively improved, so that obvious defects and weak points around the phase change material are avoided, the heat conduction capability of the cement grouting material can be effectively improved, and the heat storage performance of the cement grouting material is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of grouting materials, and particularly relates to a preparation method and application of a cement-based composite phase change grouting material. Background Art

[0002] In the field of civil engineering, grouting materials are widely used in scenarios such as foundation reinforcement, crack repair, and tunnel support. Traditional cement-based grouting materials are widely used due to their low cost and mature technology. However, with the complication of engineering environments and the upgrading of functional requirements, the existing technologies face many technical bottlenecks. First of all, traditional cement-based materials are brittle and have low toughness after curing, and are prone to cracking under temperature difference cycles or freeze-thaw actions, resulting in the peeling of the grouting body from the bedrock / structure interface. For example, in cold region tunnels or seasonal frozen soil projects, the volume deformation caused by temperature fluctuations will significantly reduce the service life of the material.

[0003] To solve the above problems, early attempts were made to add phase change materials such as paraffin and fatty acids to the cement matrix. These phase change materials can undergo phase changes at specific temperatures, store or release heat, and have the characteristics of large heat storage density and constant temperature during the phase change process. However, directly compounding phase change materials with cement-based materials will cause problems such as low strength, volume change, and attenuation of heat storage performance. Therefore, encapsulation technologies such as impregnation adsorption method, shaping encapsulation method, and capsule encapsulation method are adopted to improve compatibility and stability. Among these methods, the capsule encapsulation method is relatively simpler in process and has relatively better encapsulation effect, so it is widely used. However, the existing capsule encapsulation methods generally have a relatively complex preparation process and relatively large operation difficulty, making it difficult to be actually applied. Summary of the Invention

[0004] The purpose of the present invention is to provide a preparation method of a cement-based composite phase change grouting material to improve the physical and chemical properties such as the mechanical strength, anti-cracking performance, and heat storage performance of the cement grouting material.

[0005] To achieve the above purpose, the technical solution adopted by the present invention is as follows: A preparation method of a cement-based composite phase change grouting material, wherein the cement-based composite phase change grouting material is made of raw material components including the following weight parts: 45 parts to 55 parts of portland cement, 60 parts to 75 parts of sand and gravel aggregate, 4 parts to 6 parts of fiber reinforcing material, 1 part to 3 parts of water reducing agent, 8 parts to 15 parts of phase change material, 5 parts to 10 parts of fly ash, and 40 parts to 50 parts of water; The preparation method includes the following steps: First step, weigh each raw material component separately and prepare them; Step 2: Add each raw material into a mixer, start stirring, control the stirring rate at 500 r / min to 1000 r / min. After mechanically stirring and mixing evenly, discharge the material to obtain the cement-based composite phase change grouting material.

[0006] In a preferred example, the preparation method of the fiber reinforcement includes the following steps: Step 1: Use epoxy-based silane coupling agent as a surface modifier to modify the surface of glass fiber to obtain functionalized modified glass fiber. Step 2: Ultrasonically disperse the functionalized modified glass fiber in N,N-dimethylformamide medium to form a uniform dispersion. Then add aspartic acid into the dispersion, raise the temperature to 70°C to 80°C, stir for 3 h to 6 h. Then add benzidine disulfonic acid and a catalyst into the dispersion. After adding, further raise the temperature to 120°C to 130°C, continuously stir for 12 h to 18 h, then stop heating, cool down and discharge the material, separate and collect the solid material to obtain the fiber reinforcement.

[0007] In a preferred example, the epoxy-based silane coupling agent is selected from one of 3-glycidoxypropyltrimethoxysilane or 3-glycidoxypropyltriethoxysilane.

[0008] In a preferred example, the mass ratio of the functionalized modified glass fiber, aspartic acid and benzidine disulfonic acid is 1∶1.5 - 2∶1 - 1.8.

[0009] In a preferred example, the catalyst is selected from one of sulfamic acid or p-toluenesulfonic acid.

[0010] In a preferred example, the water reducer is selected from one of polycarboxylate water reducer or naphthalene-based water reducer.

[0011] In a preferred example, the preparation method of the phase change material includes the following steps: Step S1: Heat the solid paraffin until it completely melts, then add liquid paraffin, stir and mix evenly at a temperature of 50°C to 55°C to form paraffin oil. Then immerse expanded vermiculite in the paraffin oil, perform ultrasonic treatment at an ultrasonic frequency of 80 kHz to 100 kHz for 1 h to 2 h, and then filter. Wait until no more paraffin filters out, collect the solid material to form a precursor. Step S2: Disperse the precursor in purified water, then add carboxymethyl starch and a crosslinking agent into the formed dispersion, treat at a temperature of 60°C to 70°C for 2 h to 4 h, then cool down and discharge the material, separate the solid material to obtain the phase change material.

[0012] In a preferred example, the crosslinking agent is selected from one of sodium tripolyphosphate or sodium trimetaphosphate.

[0013] In a preferred example, the fly ash is selected from one of Class I fly ash or Class II fly ash.

[0014] Based on a general inventive concept, another object of the present invention is to provide the application of the cement-based composite phase change grouting material prepared by the above preparation method in the field of building insulation.

[0015] Compared with the prior art, the advantages and positive effects of the present invention are as follows: (1) First, the present invention modifies the surface of glass fibers by using an epoxy silane coupling agent to obtain glass fibers with epoxy groups on the surface, and obtains functionalized modified glass fibers. Then, aspartic acid is used to further modify them. Under the action of high temperature and a catalyst, aspartic acid and benzidine disulfonic acid will in-situ polymerize on the surface of the glass fibers to form glass fibers coated with a macromolecular modifier on the surface. Since a large number of sulfonic acid groups are contained in the structure of the macromolecular modifier, these sulfonic acid groups can act with the cement hydration products, thereby promoting the mutual combination of the glass fibers and the cement matrix, improving the bonding force between them, and then efficiently utilizing the reinforcing effect of the glass fibers to improve the mechanical strength and anti-cracking performance of the cement grouting material.

[0016] (2) The present invention uses expanded vermiculite as a coating material to encapsulate paraffin. Under ultrasonic conditions, paraffin can break through the interlayer barrier of expanded vermiculite and enter the interlayer of vermiculite for storage. Then, carboxymethyl starch and a cross-linking agent are used to cross-link and coat the surface of expanded graphite to prevent paraffin from oozing out under high-pressure conditions in the later stage of hydration. In addition, the carboxymethyl group in the structure of carboxymethyl starch will also act with the cement hydration products, thereby effectively improving the compatibility between the phase change material and the cement base material, avoiding obvious defects and weak points around the phase change material, and effectively improving the heat conduction ability of the cement grouting material and enhancing its heat storage performance. Detailed implementation manners

[0017] To make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in combination with specific implementation manners. However, the present invention is not limited to these embodiments. It should be noted that, on the premise of no conflict, the following-described embodiments or technical features can be arbitrarily combined to form new embodiments. In the present invention, unless otherwise specified, all parts and percentages are in mass units, and the equipment and raw materials used can be purchased from the market or are commonly used in the art. The methods in the following embodiments are all conventional methods in the art unless otherwise specified.

[0018] As used herein, the terms "comprising", "including", "containing" or any other variation thereof are intended to cover non-exclusive inclusion. For example, a composition, step, method, article or apparatus comprising the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article or apparatus.

[0019] When an equivalent, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values and lower preferred values, it should be understood that all ranges formed by any pairing of any range upper limit or preferred value with any range lower limit or preferred value are specifically disclosed, regardless of whether the ranges are separately disclosed. For example, when the range "1 to 5" is disclosed, the described range should be interpreted to include the ranges "1 to 4", "1 to 3", "1 to 2", "1 to 2 and 4 to 5", "1 to 3 and 5", etc. When a numerical range is described herein, unless otherwise stated, the range is intended to include its end values and all integers and fractions within the range.

[0020] Example 1

[0021] A cement-based composite phase change grouting material is made from raw material components including the following parts by weight: 45 parts of portland cement, 60 parts of sand and gravel aggregate, 4 parts of fiber reinforcement, 1 part of water reducer, 8 parts of phase change material, 5 parts of Class I fly ash, 40 parts of water; The preparation method of the cement-based composite phase change grouting material includes the following steps: First step, weigh each raw material component separately and get them ready; Second step, add each raw material into a mixer, start stirring, control the stirring rate at 500 r / min, after mechanically stirring and mixing evenly, discharge the material to obtain the cement-based composite phase change grouting material.

[0022] Among them, the preparation method of the fiber reinforcement includes the following steps: Step 1, ultrasonically disperse 1.2 g of glass fiber in ethanol with a volume fraction of 70%, then add 2.5 g of 3-glycidoxy triethoxysilane. After adding, raise the temperature to 75 °C, keep warm for 6 h, then cool down and discharge the material to obtain functionalized modified glass fiber; Step 2, ultrasonically disperse 1.6 g of functionalized modified glass fiber in N,N-dimethylformamide medium to form a uniform dispersion liquid, then add 3 g of aspartic acid to the dispersion liquid, raise the temperature to 75 °C, stir for 4 h, then add 2.5 g of benzidine disulfonic acid and 0.1 g of p-toluenesulfonic acid to the dispersion liquid. After adding, further raise the temperature to 125 °C, continuously stir for 16 h, then stop heating, cool down and discharge the material, separate and collect the solid material to obtain the fiber reinforcement.

[0023] Among them, the preparation method of the phase change material includes the following steps: Step S1: After heating 1 g of solid paraffin until it completely melts, add 0.5 g of liquid paraffin, stir and mix evenly at a temperature of 50 °C to form paraffin oil. Then, immerse 0.1 g of expanded vermiculite in the paraffin oil, perform ultrasonic treatment for 2 h at an ultrasonic frequency of 100 kHz, and then filter. Wait until no more paraffin filters out, collect the solid material to form a precursor material. Step S2: Disperse 0.5 g of the precursor material in purified water, then add 1.8 g of carboxymethyl starch and 0.2 g of sodium tripolyphosphate to the formed dispersion liquid, treat it at a temperature of 65 °C for 3 h, then cool down and discharge the material, and separate the solid material to obtain the phase change material.

[0024] Example 2

[0025] A cement-based composite phase change grouting material is made of raw material components including the following parts by weight: 50 parts of portland cement, 65 parts of sand and gravel aggregate, 5.5 parts of fiber reinforcing material, 2.5 parts of polycarboxylate water reducer, 10 parts of phase change material, 6 parts of class II fly ash, 45 parts of water; The preparation method of the cement-based composite phase change grouting material includes the following steps: The first step: Weigh each raw material component separately and prepare them. The second step: Add each raw material to a mixer, start stirring, control the stirring rate at 800 r / min, and after mechanical stirring and mixing evenly, discharge the material to obtain the cement-based composite phase change grouting material.

[0026] The preparation method of the cement-based composite phase change grouting material includes the following steps: The first step: Weigh each raw material component separately and prepare them. The second step: Add each raw material to a mixer, start stirring, control the stirring rate at 500 r / min, and after mechanical stirring and mixing evenly, discharge the material to obtain the cement-based composite phase change grouting material.

[0027] Among them, the preparation method of the fiber reinforcing material includes the following steps: Step 1: Ultrasonically disperse 1.2 g of glass fiber in ethanol with a volume fraction of 70%, then add 2.5 g of 3-glycidoxypropyltrimethoxysilane. After adding, raise the temperature to 75 °C, keep it warm for 6 h, then cool down and discharge the material to obtain functionalized modified glass fiber. Step 2: Ultrasonically disperse 1.6 g of functionalized modified glass fiber in N,N-dimethylformamide medium to form a uniform dispersion. Then add 3 g of aspartic acid to the dispersion, raise the temperature to 75 °C, stir for 4 h, and then add 2.5 g of benzidine disulfonic acid and 0.1 g of p-toluenesulfonic acid to the dispersion. After adding, further raise the temperature to 125 °C, continuously stir for 16 h, stop heating, cool down and discharge the material, separate and collect the solid material to obtain the fiber reinforcing material.

[0028] Among them, the preparation method of the phase change material includes the following steps: Step S1: Heat 1 g of solid paraffin until it completely melts, add 0.5 g of liquid paraffin, stir and mix evenly at a temperature of 50 °C to form paraffin oil. Then immerse 0.1 g of expanded vermiculite in the paraffin oil, perform ultrasonic treatment at an ultrasonic frequency of 100 kHz for 2 h, then filter. Wait until no more paraffin filters out, collect the solid material to form the precursor material; Step S2: Disperse 0.5 g of the precursor material in purified water, and then add 1.8 g of carboxymethyl starch and 0.2 g of sodium trimetaphosphate to the formed dispersion. Treat at a temperature of 65 °C for 3 h, then cool down and discharge the material, separate the solid material to obtain the phase change material.

[0029] Example 3

[0030] A cement-based composite phase change grouting material is made of raw material components including the following weight parts: 55 parts of portland cement, 75 parts of sand and gravel aggregate, 6 parts of fiber reinforcing material, 3 parts of polycarboxylate water reducer, 15 parts of phase change material, 10 parts of Class II fly ash, 50 parts of water; The preparation method of the cement-based composite phase change grouting material includes the following steps: The first step: Weigh each raw material component separately and prepare them. The second step: Add each raw material to a mixer, start stirring, control the stirring rate at 1000 r / min, mechanically stir and mix evenly, then discharge the material to obtain the cement-based composite phase change grouting material.

[0031] The preparation method of the cement-based composite phase change grouting material includes the following steps: The first step: Weigh each raw material component separately and prepare them. The second step: Add each raw material to a mixer, start stirring, control the stirring rate at 500 r / min, mechanically stir and mix evenly, then discharge the material to obtain the cement-based composite phase change grouting material.

[0032] Among them, the preparation method of the fiber reinforcing material includes the following steps: Step 1: Ultrasonically disperse 1.2 g of glass fiber in ethanol with a volume fraction of 70%. Then add 2.5 g of 3-glycidoxytrimethoxysilane. After adding, raise the temperature to 75 °C, hold for 6 h, then cool down and discharge to obtain functionalized modified glass fiber. Step 2: Ultrasonically disperse 1.6 g of functionalized modified glass fiber in N,N-dimethylformamide medium to form a homogeneous dispersion. Then add 3 g of aspartic acid to the dispersion, raise the temperature to 75 °C, stir for 4 h, and then add 2.5 g of benzidine disulfonic acid and 0.1 g of sulfamic acid to the dispersion. After adding, further raise the temperature to 125 °C, continuously stir for 16 h, then stop heating, cool down and discharge, separate and collect the solid material to obtain fiber reinforcing material.

[0033] The preparation method of the phase change material includes the following steps: Step S1: Heat 1 g of solid paraffin until it completely melts, add 0.5 g of liquid paraffin, stir and mix evenly at a temperature of 50 °C to form paraffin oil. Then immerse 0.1 g of expanded vermiculite in the paraffin oil, perform ultrasonic treatment at an ultrasonic frequency of 100 kHz for 2 h, then filter. Wait until no more paraffin filters out, collect the solid material to form a precursor material. Step S2: Disperse 0.5 g of the precursor material in purified water, then add 1.8 g of carboxymethyl starch and 0.2 g of sodium trimetaphosphate to the formed dispersion, treat at a temperature of 65 °C for 3 h, then cool down and discharge, separate the solid material to obtain the phase change material.

[0034] Comparative Example 1

[0035] Replace "fiber reinforcing material" in the raw material components with "glass fiber", and the others are the same as in Example 2.

[0036] Comparative Example 2

[0037] The raw material components do not contain "polycarboxylate superplasticizer", and the others are the same as in Example 2.

[0038] Comparative Example 3

[0039] Add 10 parts of "solid paraffin" additionally to the raw material components, and the others are the same as in Example 2.

[0040] Test Example 1

[0041] Conduct mechanical property tests with reference to GB / T 17671-1999; Conduct cracking property tests with reference to JGJ / T 70-2009; Heating performance test: The grouting materials in Examples 1-3 and Comparative Examples 1-3 were made into test samples of 10 cm × 10 cm × 2 cm, placed at the same outdoor location for direct sunlight, and the temperature on the other side of the sample was measured using a handheld electronic temperature measuring device; the results are shown in Table 1 below.

[0042] Table 1 Results of each performance test

[0043] The above embodiments are only the preferred embodiments of the present invention. Any simple modification, modification, and alternative change made to the above embodiments based on the technical essence of the present invention all fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a cement-based composite phase change grouting material, characterized in that: The cement-based composite phase change grouting material is made of the following raw material components in parts by weight: 45-55 parts of Portland cement, 60-75 parts of sand and gravel aggregate, 4-6 parts of fiber reinforcement, 1-3 parts of water reducer, 8-15 parts of phase change material, 5-10 parts of fly ash, 40-50 parts of water; The preparation method comprises the following steps: The first step is to weigh each raw material component separately and prepare them; The second step is to add all the raw materials into the mixer, start stirring, control the stirring rate to 500r / min-1000r / min, and after mechanical stirring and mixing evenly, discharge the materials to obtain the cement-based composite phase change grouting material.

2. The method for preparing a cement-based composite phase change grouting material according to claim 1, characterized in that: The method for preparing the fiber reinforcement material comprises the following steps: Step 1: Using epoxy silane coupling agent as surface modifier to modify the surface of glass fiber to obtain functionalized modified glass fiber; Step 2: Ultrasonically disperse the functionalized modified glass fiber in an N,N-dimethylformamide medium to form a uniform dispersion, then add aspartic acid to the dispersion, heat it to 70°C to 80°C, stir it for 3h to 6h, then add benzidine disulfonic acid and a catalyst to the dispersion, after the addition, further increase the temperature to 120°C to 130°C, continue stirring for 12h to 18h, stop heating, cool down and discharge, separate and collect the solid material, and obtain a fiber reinforced material.

3. The method for preparing a cement-based composite phase change grouting material according to claim 2, characterized in that: The epoxy silane coupling agent is selected from 3-glycidyloxy trimethoxy silane or 3-glycidyloxy triethoxy silane.

4. The method for preparing a cement-based composite phase change grouting material according to claim 2, characterized in that: The mass ratio of the functionalized modified glass fiber, aspartic acid and benzidine disulfonic acid is 1:1.5-2:1-1.

8.

5. The method for preparing a cement-based composite phase change grouting material according to claim 2, characterized in that: The catalyst is selected from one of aminosulfonic acid and p-toluenesulfonic acid.

6. The method for preparing a cement-based composite phase change grouting material according to claim 1, characterized in that: The water reducer is selected from a polycarboxylic acid water reducer or a naphthalene water reducer.

7. The method for preparing a cement-based composite phase change grouting material according to claim 1, characterized in that: The method for preparing the phase change material comprises the following steps: Step S1, after heating solid paraffin until completely melted, adding liquid paraffin, stirring and mixing at a temperature of 50° C. to 55° C. to form paraffin oil, then immersing expanded vermiculite in the paraffin oil, ultrasonically treating it at an ultrasonic frequency of 80kHz to 100kHz for 1h to 2h, and then filtering until no more paraffin is filtered out, collecting solid material to form a precursor material; Step S2, dispersing the precursor in purified water, adding carboxymethyl starch and a cross-linking agent to the formed dispersion, treating it in a temperature environment of 60°C to 70°C for 2h to 4h, cooling the material, separating the solid material, and obtaining a phase change material.

8. The method for preparing a cement-based composite phase change grouting material according to claim 7, characterized in that: The cross-linking agent is selected from one of sodium tripolyphosphate and sodium trimetaphosphate.

9. The method for preparing a cement-based composite phase change grouting material according to claim 1, characterized in that: The fly ash is selected from one of Class I fly ash and Class II fly ash.

10. Use of a cement-based composite phase-change grouting material prepared by the preparation method according to any one of claims 1 to 9 in the field of building thermal insulation.

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