Application of fluorescent dyes in determining the pore pressure of cement-based materials in different environments

Abstract

This invention relates to the field of cement-based materials technology, and in particular to the application of fluorescent dyes in determining the pore pressure of cement-based materials under different environments. The invention first dissolves a fluorescent dye in an organic solvent and water to obtain a fluorescent dye solution. The cement-based material is then mixed with water to obtain a paste. The fluorescent dye solution is then added to the paste, which is shaped and cut into thin slices. These slices are further placed under different environments, and the fluorescence intensity is measured using a fluorescence spectrometer to determine the pore pressure of the cement-based material in different environments. Higher fluorescence intensity indicates greater pore pressure. This invention uses the mechanochromic properties of tetraphenylethylene to determine the pore pressure of cement-based materials, which is convenient, quick, and provides good visual results.

Description

Technical Field

[0001] This invention relates to the field of cement-based materials technology, and in particular to the application of fluorescent dyes in determining the pore pressure of cement-based materials in different environments. Background Technology

[0002] As a porous material, cement-based materials experience changes in pore pressure during service, especially under conditions of significant wet-dry cycles. With increasing pore pressure, the internal structure of cement-based materials gradually loosens, pores enlarge, and cracks propagate, leading to microcrack propagation and decreased material durability. Microcrack propagation is closely related to the pore pressure within cement-based materials; therefore, detecting the pore pressure of cement-based materials is crucial for durability research. According to empirical formulas, the effective pore pressure within cement-based materials is a function of the pore radius. By establishing a pore size distribution function and calculating the characteristic pore size R of cement paste, the average effective pore pressure P under specific temperature T and relative humidity RH conditions can be determined. However, current research on the actual testing of pore pressure in cement-based materials mainly focuses on high-temperature bursting. Nevertheless, due to the complex pore structure of cement-based materials and their size being far smaller than commonly used mechanical, electronic, or digital sensors, determining the magnitude of pore pressure in cement-based materials under different environments presents a challenging experimental requirement. Summary of the Invention

[0003] To address the aforementioned problems, the purpose of this invention is to provide an application of fluorescent dyes in determining the pore pressure of cement-based materials under different environments. This invention uses the mechanochromic properties of tetraphenylethylene (TPE) to determine the pore pressure of cement-based materials, which is convenient, quick, and provides good visual results.

[0004] The objective of this invention can be achieved through the following technical solutions:

[0005] This invention provides an application of fluorescent dyes in determining the pore pressure of cement-based materials in different environments, comprising the following steps:

[0006] (1) Dissolve the fluorescent dye in an organic solvent and water to obtain a fluorescent dye solution;

[0007] (2) Mix cement with fluorescent dye solution to obtain cement-based material, and cut it into thin slices after molding;

[0008] (3) Place the thin film obtained in step (2) in different environments and use a steady-state transient fluorescence spectrometer to test the fluorescence intensity of the thin film to determine the magnitude of the pore pressure of the cement-based material in different environments;

[0009] The higher the fluorescence intensity, the greater the pore pressure of the cement-based material.

[0010] In one embodiment of the present invention, in step (1), the ratio of fluorescent dye: organic solvent: water is 2mg:5-9ml:1-5ml.

[0011] In one embodiment of the present invention, the ratio of fluorescent dye: organic solvent: water is 1 mg: 3 ml: 2 ml.

[0012] In one embodiment of the present invention, the fluorescent dye is tetraphenylethylene, and the chemical structural formula of tetraphenylethylene is shown below:

[0013]

[0014] In one embodiment of the present invention, the organic solvent is selected from polyethylene glycol, ethylene glycol, or ethanol.

[0015] In one embodiment of the present invention, the organic solvent is polyethylene glycol.

[0016] In one embodiment of the present invention, in step (2), the cement is P II 52.5 cement.

[0017] In one embodiment of the present invention, in step (2), the mass ratio of the cement to the fluorescent dye solution is 100g:50mL.

[0018] In one embodiment of the present invention, in step (2), the size of the sheet is 10mm×10mm×10mm.

[0019] In one embodiment of the present invention, in step (3), the excitation wavelength is 362 nm during the fluorescence intensity test.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) This invention uses fluorescent dyes to characterize the pore pressure changes of cement-based materials, especially the pore pressure at the nanoscale such as micropores and mesopores, without causing damage to the pores themselves, thus enabling non-destructive testing.

[0022] (2) This invention characterizes the pore pressure change of unsaturated cement-based materials by utilizing the pressure sensitivity characteristics of fluorescent dyes. It is convenient, quick, and has good visual effects, providing a new method for measuring the pore pressure of cement-based materials.

[0023] (3) The present invention uses tetraphenylethylene reagent to test the pore pressure of cement-based materials. The significant stability of tetraphenylethylene reagent is the greatest advantage. It was found that the higher the fluorescence intensity of tetraphenylethylene, the greater the pore pressure of cement-based materials. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the fluorescence intensity of the thin films prepared in Examples 1-5 without being coated with epoxy resin AB glue;

[0025] Figure 2 This is a schematic diagram of the fluorescence intensity of the thin films prepared in Examples 1-5 after being coated with epoxy resin AB glue (2:1);

[0026] Figure 3 This is a schematic diagram of the fluorescence intensity of the thin films prepared in Examples 1-5 after being coated with epoxy resin AB glue (3:1);

[0027] Figure 4 This is a schematic diagram showing the fluorescence intensity of the thin film prepared in Example 6 under pressure using tungsten carbide test blocks of different weights. Detailed Implementation

[0028] This invention provides an application of fluorescent dyes in determining the pore pressure of cement-based materials in different environments, comprising the following steps:

[0029] (1) Dissolve the fluorescent dye in an organic solvent and water to obtain a fluorescent dye solution;

[0030] (2) Mix cement with fluorescent dye solution to obtain cement-based material, and cut it into thin slices after molding;

[0031] (3) Place the thin film obtained in step (2) in different environments and use a steady-state transient fluorescence spectrometer to test the fluorescence intensity of the thin film to determine the magnitude of the pore pressure of the cement-based material in different environments;

[0032] The higher the fluorescence intensity, the greater the pore pressure of the cement-based material.

[0033] In one embodiment of the present invention, in step (1), the ratio of fluorescent dye: organic solvent: water is 2mg:5-9ml:1-5ml.

[0034] In one embodiment of the present invention, the ratio of fluorescent dye: organic solvent: water is 1 mg: 3 ml: 2 ml.

[0035] In one embodiment of the present invention, the fluorescent dye is tetraphenylethylene, and the chemical structural formula of tetraphenylethylene is shown below:

[0036]

[0037] In one embodiment of the present invention, the organic solvent is selected from polyethylene glycol, ethylene glycol, or ethanol.

[0038] In one embodiment of the present invention, the organic solvent is polyethylene glycol.

[0039] In one embodiment of the present invention, in step (2), the cement is P II 52.5 cement.

[0040] In one embodiment of the present invention, in step (2), the mass ratio of the cement to the fluorescent dye solution is 100g:50mL.

[0041] In one embodiment of the present invention, in step (2), the size of the sheet is 10mm×10mm×10mm.

[0042] In one embodiment of the present invention, in step (3), the excitation wavelength is 362 nm during the fluorescence intensity test.

[0043] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments.

[0044] Unless otherwise specified, all reagents used in the following embodiments are commercially available reagents, and all detection methods and techniques used are conventional detection methods and techniques in the art.

[0045] In the following embodiments, fluorescence spectroscopy was performed using a steady-state transient fluorescence spectrometer. The instrument used was an Edinburgh FLS980, with a spectral detection range of 200-870 nm. The pore structure characteristics were studied using mercury intrusion porosimetry (MIP). The instrument used was a PoreMaster 33 fully automated mercury intrusion porosimeter manufactured by Quanta Instruments, Inc. This instrument can analyze one high-pressure sample and two low-pressure samples. The low-pressure chamber is mainly used for evacuating the expanding agent to a vacuum, introducing mercury, and performing the low-pressure analysis. The pressure range is 0–345 kPa (0–50 psia), corresponding to a pore size range of 360–3.6 μm. The high-pressure chamber is mainly used for the high-pressure analysis, with a pressure range from standard atmospheric pressure to 414 MPa (60,000 psia), corresponding to a pore size range of 0.003–360 μm.

[0046] Example 1

[0047] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cementitious materials encapsulated in epoxy resin AB glue.

[0048] (1) Dissolve 10 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0049] (2) Mix 100g of P II 52.5 cement with 50mL of tetraphenylethylene solution to obtain a neat slurry. After molding, cut it into thin slices (10mm×10mm×10mm) and transfer it to a curing room at 20℃ and 95% relative humidity for 7 days.

[0050] (3) Take the thin slices cured in step (2) and wrap them with epoxy resin AB glue with a mass ratio of 3:1 and 2:1 respectively. Use the unwrapped thin slices as the control group. Use a steady-state transient fluorescence spectrometer to test the fluorescence intensity. Set the excitation wavelength to 362nm and observe the fluorescence intensity of the samples (the results are as follows). Figure 1 , Figure 2 and Figure 3 (As shown).

[0051] Example 2

[0052] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cementitious materials encapsulated by epoxy resin AB glue.

[0053] (1) Dissolve 20 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0054] (2) Mix 100g of P II 52.5 cement with 50mL of tetraphenylethylene solution to obtain a neat slurry. After molding, cut it into thin slices (10mm×10mm×10mm) and transfer it to a curing room at 20℃ and 95% relative humidity for 7 days.

[0055] (3) Take the thin slices cured in step (2) and wrap them with epoxy resin AB glue with a mass ratio of 3:1 and 2:1 respectively. Use the unwrapped thin slices as the control group. Use a steady-state transient fluorescence spectrometer to test the fluorescence intensity. Set the excitation wavelength to 362nm and observe the fluorescence intensity of the samples (the results are as follows). Figure 1 , Figure 2 and Figure 3 (As shown).

[0056] Example 3

[0057] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cementitious materials encapsulated by epoxy resin AB glue.

[0058] (1) Dissolve 30 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0059] (2) Mix 100g of P II 52.5 cement with 50mL of tetraphenylethylene solution to obtain a neat slurry. After molding, cut it into thin slices (10mm×10mm×10mm) and transfer it to a curing room at 20℃ and 95% relative humidity for 7 days.

[0060] (3) Take the thin slices cured in step (2) and wrap them with epoxy resin AB glue with a mass ratio of 3:1 and 2:1 respectively. Use the unwrapped thin slices as the control group. Use a steady-state transient fluorescence spectrometer to test the fluorescence intensity. Set the excitation wavelength to 362nm and observe the fluorescence intensity of the samples (the results are as follows). Figure 1 , Figure 2 and Figure 3 (As shown).

[0061] Example 4

[0062] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cementitious materials encapsulated by epoxy resin AB glue.

[0063] (1) Dissolve 40 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0064] (2) Mix 100g of P II 52.5 cement with 50mL of tetraphenylethylene solution to obtain a neat slurry. After molding, cut it into thin slices (10mm×10mm×10mm) and transfer it to a curing room at 20℃ and 95% relative humidity for 7 days.

[0065] (3) Take the thin slices cured in step (2) and wrap them with epoxy resin AB glue with a mass ratio of 3:1 and 2:1 respectively. Use the unwrapped thin slices as the control group. Use a steady-state transient fluorescence spectrometer to test the fluorescence intensity. Set the excitation wavelength to 362nm and observe the fluorescence intensity of the samples (the results are as follows). Figure 1 , Figure 2 and Figure 3 (As shown).

[0066] Example 5

[0067] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cementitious materials encapsulated by epoxy resin AB glue.

[0068] (1) Dissolve 50 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0069] (2) Mix 100g of P II 52.5 cement with 50mL of tetraphenylethylene solution to obtain a neat slurry. After molding, cut it into thin slices (10mm×10mm×10mm) and transfer it to a curing room at 20℃ and 95% relative humidity for 7 days.

[0070] (3) Take the thin slices cured in step (2) and wrap them with epoxy resin AB glue with a mass ratio of 3:1 and 2:1 respectively. Use the unwrapped thin slices as the control group. Use a steady-state transient fluorescence spectrometer to test the fluorescence intensity. Set the excitation wavelength to 362nm and observe the fluorescence intensity of the samples (the results are as follows). Figure 1 , Figure 2 and Figure 3 (As shown).

[0071] Example 6

[0072] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cement-based materials under different pressure conditions.

[0073] (1) Dissolve 250 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0074] (2) Mix 100g of P II 52.5 cement with 50mL of tetraphenylethylene solution to obtain a neat slurry. After molding, cut it into thin slices (10mm×10mm×10mm) and transfer it to a curing room at 20℃ and 95% relative humidity for 7 days.

[0075] (3) After curing in step (2), the thin slices were subjected to pressure using tungsten carbide test blocks of different masses. The pressures applied to the thin slices were 20 kPa, 58 kPa, 75 kPa, and 92 kPa, respectively. The unpressed thin slices (0 kPa) were used as the control group. The fluorescence intensity was measured using a steady-state transient fluorescence spectrometer with an excitation wavelength of 362 nm. The fluorescence intensity of the samples was observed (results are shown in the figure). Figure 4 (As shown).

[0076] Conclusion: Through Figure 1-4 It was found that applying epoxy resin coating and heavy tungsten carbide to create a pressure environment for the thin films significantly increased the fluorescence intensity under external pressure. However, the profiles of all spectra (including their curve shapes and peak positions) were almost identical, indicating that the basic molecular structure of tetraphenylethylene did not change under the influence of external pressure. The integral area of ​​the PL peak was sensitive to the applied pressure, exhibiting a unique effect of pressure-enhanced emission, with fluorescence intensity increasing rapidly with increasing pressure. Applying external pressure to the thin films of cement-based materials can enhance the fluorescence intensity of tetraphenylethylene. Furthermore, the fluorescence intensity of tetraphenylethylene can be used to determine the pore pressure of cement-based materials.

[0077] Example 7

[0078] This embodiment provides an application of fluorescent dyes in determining the pore pressure of cement-based materials in different environments.

[0079] (1) Dissolve 20 mg of tetraphenylethylene in 30 mL of polyethylene glycol and 20 mL of water to obtain a tetraphenylethylene solution;

[0080] (2) After mixing P II 52.5 cement with fly ash (the specific dosage is shown in Table 1), mix it with the tetraphenylethylene solution obtained in step (1) (the specific dosage is shown in Table 1). Figure 1 As shown), after molding, it is cut into thin slices (10mm×10mm×10mm); and then transferred to a curing room at 20℃ with different relative humidities (90%, 95%, 98%) for 7 days.

[0081] (4) Take the thin slice after curing in step (3), use a PoreMaster33 fully automatic mercury porosimeter to test its effective pore pressure and characteristic pore size, use a steady-state transient fluorescence spectrometer to test the fluorescence intensity, set the excitation wavelength to 362nm, and observe the fluorescence intensity of the sample (the results are shown in Table 2).

[0082] Table 1 Summary of Raw Material Usage for Each Sample

[0083]

[0084] Table 2 Summary of characteristic pore size, pore pressure and fluorescence intensity of samples under different environments

[0085]

[0086] Conclusion: Table 2 shows that the fluorescence intensity increases or decreases with the increase or decrease of pore pressure; this further verifies that the fluorescence intensity of tetraphenylethylene can sense the effective pore pressure inside cement-based materials, that is, the magnitude of pore pressure in cement-based materials can be determined by the fluorescence intensity of tetraphenylethylene.

[0087] The above description of the embodiments is provided to enable those skilled in the art to understand and use the invention. It will be apparent to those skilled in the art that various modifications can be made to these embodiments, and the general principles described herein can be applied to other embodiments without inventive effort. Therefore, the present invention is not limited to the above embodiments, and any improvements and modifications made by those skilled in the art based on the disclosure of the present invention without departing from the scope of the invention should be within the protection scope of the present invention.

Claims

1. The application of a fluorescent dye in determining the pore pressure of cement-based materials in different environments, characterized in that, Includes the following steps: (1) Dissolve the fluorescent dye in an organic solvent and water to obtain a fluorescent dye solution; (2) Mix cement with fluorescent dye solution to obtain cement-based material, and cut it into thin slices after molding; (3) Place the thin film obtained in step (2) in different environments and use a steady-state transient fluorescence spectrometer to test the fluorescence intensity of the thin film to determine the pore pressure of the cement-based material in different environments; Among them, the higher the fluorescence intensity, the greater the pore pressure of the cement-based material; In step (1), the ratio of fluorescent dye: organic solvent: water is 1 mg: 3 ml: 2 ml; The fluorescent dye is tetraphenylethylene; In step (2), the ratio of cement to fluorescent dye solution is 100g:50mL; The sheet measures 10mm × 10mm × 10mm; In step (3), the excitation wavelength is 362 nm during the fluorescence intensity test.

2. The application of a fluorescent dye according to claim 1 in determining the pore pressure of cement-based materials in different environments, characterized in that, The organic solvent is selected from polyethylene glycol, ethylene glycol, or ethanol.

3. The application of a fluorescent dye according to claim 2 in determining the pore pressure of cement-based materials in different environments, characterized in that, The organic solvent is polyethylene glycol.

4. The application of a fluorescent dye according to claim 1 in determining the pore pressure of cement-based materials in different environments, characterized in that, In step (2), the cement is PII 52.5 cement.

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