Method for detecting carbonation depth of cement-based materials

Abstract

The application discloses a detection method for carbonation depth of cement-based materials, comprising the following steps: placing mud test pieces into a rapid carbonation test box to perform rapid carbonation to different carbonation ages; testing dielectric constants of the cement test pieces of different carbonation ages from top to bottom along the carbonation depth direction, taking the depth value as the carbonation depth I based on the dielectric constant when the dielectric constant changes greatly; testing the carbonation depth II of the cement test pieces of the carbonation age by adopting a phenolphthalein method; fitting two groups of data by adopting a chemometrics method according to the obtained carbonation depth I and the carbonation depth II, and establishing a fitting equation of the carbonation depth I and the carbonation depth II; and then realizing rapid and efficient detection of the carbonation depth of the cement test pieces. The test method is simple and convenient without damaging the test pieces, the detection result is relatively accurate, and a new thought is provided for rapid detection of the carbonation depth of cement-based materials.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of detection, and particularly relates to a detection method for carbonation depth of cement-based materials. BACKGROUND

[0002] Carbonation of concrete is a kind of chemical corrosion of concrete, and the specific steps include: CO2 gas in the air penetrates into the concrete through the pores of hardened concrete, reacts with the alkaline substance (Ca(OH)2) to generate carbonate (CaCO3) and water, and reduces the alkalinity of the concrete. In reinforced concrete, the carbonation of concrete leads to the decrease of internal pH value, which further causes the rusting of steel bars and other problems, and thus reduces the service life of the structure, which is a major problem of reinforced concrete structures. Carbonation mainly reduces the pH value of the pore solution in the cement paste, thereby indirectly reducing the protection ability of the concrete to the steel bars; this process starts from the surface of the concrete and gradually deepens with time.

[0003] At present, the main method for detecting carbonation depth in China is the phenolphthalein reagent test method. JGJT 23 Technical Specification for Testing Concrete Compressive Strength by Rebound Method indicates that the carbonation depth of concrete solid structures needs to form a hole with a diameter of about 15 mm on the surface of the test area, and the depth should be greater than the carbonation depth of the concrete. Meanwhile, a 1% phenolphthalein alcohol solution is dropped on the edge of the inner wall of the hole until the carbonized and uncarbonized boundaries are clear. GB / T 50082 Standard for Testing Methods for Long-term Performance and Durability of Ordinary Concrete specifies that when carbonation is performed for 3d, 7d, 14d and 28d, the test pieces are taken out, broken and tested for carbonation depth. The prismatic test piece should be broken from one end by the splitting method on the pressure testing machine or by the dry sawing method; the thickness of each cut should be half of the width of the test piece, and the cut surface of the broken test piece should be sealed with paraffin after cutting, and then placed in the box for further carbonation until the next test period; when a cubic test piece is used, it should be split in the middle; the cubic test piece should be tested only once, and cannot be reused after splitting and testing the carbonation depth; then the test piece obtained by cutting is brushed to remove the residual powder on the surface, and then a 1% phenolphthalein alcohol solution (the alcohol solution contains 20% distilled water) is sprayed or dropped on it; after about 30s, the carbonation depth of each point is measured with a steel ruler according to the original marked measurement points every 10mm. However, the above detection methods usually have the following disadvantages: 1) the test piece needs to be broken, which is a one-time detection and cannot be repeated; 2) the unevenness of the split surface makes it difficult to determine the color change boundary of the reagent; 3) the number of sampling times is limited; and 4) human reading errors are prone to occur.

[0004] Therefore, it is of great significance to further explore a simple, efficient and non-destructive carbonation depth detection method. SUMMARY

[0005] The main purpose of the present application is to provide a new detection method for carbonation depth of cement-based materials, which can realize rapid and efficient detection of carbonation depth of cement-based materials by testing the dielectric constant of cement-based materials before and after carbonation, using the regular change of dielectric constant with the carbonation process of cement-based materials, and establishing the mathematical relationship between the dielectric constant detection of carbonation depth and the phenolphthalein detection of carbonation depth.

[0006] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is:

[0007] A detection method for carbonation depth of cement-based materials, comprising the following steps:

[0008] 1) Cement test piece preparation: prepare cement mortar, shape, demould, standard curing, dry, and obtain cement test piece;

[0009] 2) Rapid carbonation test: place the obtained cement test piece into a rapid carbonation test box for rapid carbonation to different carbonation ages;

[0010] 3) Carbonation depth detection:

[0011] Test the dielectric constant of the cement test piece at different carbonation ages obtained in step 2) from top to bottom along the carbonation depth direction, and when the dielectric constant changes greatly, the depth value is taken as the carbonation depth I based on the dielectric constant;

[0012] Test the carbonation depth II of the cement test piece at the carbonation age by phenolphthalein method;

[0013] 4) According to the obtained carbonation depth I and carbonation depth II, use chemometrics method to fit the two groups of data, and establish the fitting equation of carbonation depth I and carbonation depth II.

[0014] In the above scheme, the demoulding is performed after shaping for 24-48h in step 1).

[0015] In the above scheme, the standard curing conditions are: placing in a curing room with temperature of 18-22℃ and humidity not less than 95% for curing for 26-28d; the drying temperature is 60-65℃, and the time is 45-50h.

[0016] Further, the standard curing conditions are performed according to GB / T 50082 "Standard Test Methods for Long-Term Performance and Durability of Ordinary Concrete", the curing time is 26d, the drying temperature is 60℃, and the time is 48h.

[0017] In the above scheme, the components in the cement mortar and the weight percentage thereof include: cement 11-27 parts, fly ash 5-13 parts, mineral powder 4-6 parts, sand 49-60 parts, water 10-13 parts, and water reducing agent 0.4-1.0 parts.

[0018] In the above scheme, the size of the cement test piece is 100mmx100mmx400mm or 100mmx100mmx350mm, which is a common size of the concrete carbonation test piece.

[0019] In the above scheme, after the drying treatment of the cement test piece, the remaining surfaces are sealed by using paraffin or the like, except for one surface (or two opposite surfaces) to be carbonated.

[0020] In the above scheme, the carbon dioxide concentration used in the rapid carbonation step of step 2) is 17-23vol%, the relative humidity is 65-75%, and the temperature is 18-22℃.

[0021] In the above scheme, the carbonation age can be selected from 3d, 7d, 14d and 28d, etc.

[0022] In the above scheme, the dielectric constant test step uses a dielectric constant tester.

[0023] In the above scheme, the large amplitude change of the dielectric constant in step 3) is the first time to reduce to below 5.3 (F / m), and the corresponding depth value relative to the surface of the concrete is the carbonation depth I.

[0024] Further, in step 3), the large amplitude change of the dielectric constant is the first time to reduce to 5.3-5.0 (F / m).

[0025] In the above scheme, the specific detection steps of the carbonation depth I include: removing the packaging materials such as paraffin on the side of the cement test piece, and using a dielectric constant tester (high frequency (microwave) dielectric constant tester (coaxial resonant cavity)) to test the dielectric constant corresponding to different depth positions from top to bottom (from surface to inside) along the thickness direction (carbonation depth direction) of the cement test piece, wherein the probe moving speed is 5-10mm / min, and the test frequency is 0.5-1.3GHz.

[0026] In the above scheme, after the dielectric constant test is completed, the carbonation depth II is determined by using the phenolphthalein method for the concrete test piece; wherein the prism test piece should be broken by the splitting method on the pressure testing machine or by the dry saw method from one end, the thickness of each cut should be half of the width of the test piece, after cutting, the cut surface of the broken test piece is sealed with paraffin, and then put into the box for continuous carbonation until the next test period; when using a cubic test piece, the test piece should be split in the middle, the cubic test piece should be tested only once, and after the carbonation depth is tested by splitting, it cannot be reused.

[0027] In the above scheme, the chemometrics method can be selected from the least square method, etc.

[0028] In the above scheme, in the fitting process, data with error exceeding -10-10% is first removed.

[0029] In the above scheme, the carbonation depth I of the cement test piece to be measured is measured by using the method corresponding to step 3), and then the fitting equation of the obtained carbonation depth I and carbonation depth II is used to realize rapid and efficient detection of the carbonation depth of the cement test piece to be measured.

[0030] Compared with the prior art, the present application has the following beneficial effects:

[0031] 1) The present application first introduces the dielectric constant of cement-based materials, uses the regular change of the dielectric constant with the carbonation process to construct the mathematical relationship between the dielectric constant and the carbonation depth, and then reflects and calculates the carbonation depth of the cement material through the regular change of the dielectric constant, so as to realize rapid and efficient detection of the carbonation depth of the cement material;

[0032] 2) In the specific test process of the present application, the test piece does not need to be broken, and the problems such as reading error caused by the multiple phenolphthalein reagent test method can be avoided, a large amount of test manpower and time can be saved, and the present application can be repeatedly and massively used with good repeatability;

[0033] 3) The dielectric constant method used in the present application is relatively simple, does not require complex and strict sample preparation requirements, is easy to operate, and is suitable for popularization and application. BRIEF DESCRIPTION OF DRAWINGS

[0034] Figure 1 The fitting results obtained by the test method described in Example 1. DETAILED DESCRIPTION

[0035] In order to make the purpose, technical scheme and advantages of the present application clearer and more apparent, the present application will be further described in detail below with reference to examples. It should be understood that the specific examples described herein are only used to explain the present application and do not limit the present application.

[0036] In the following examples, the cement used is Tianyu Hua Xip·O 42.5 ordinary portland cement produced by Xinjiang Jimusar Cement Plant, with a density of 3.1 / g·cm -3 , a fineness of 3%, and a water requirement of 24.7% at standard consistency.

[0037] The fly ash used is F-class II fly ash produced by Urumqi Hongyanchi No. 2 Power Plant, with a fineness of 22.9%, a specific surface area of 243 m 2 / kg, a water requirement ratio of 102%, and a loss on ignition of 2.8%.

[0038] The mineral powder used is S75-grade mineral powder produced by Baixin Shengyuan Building Material Co., Ltd., with a specific surface area of 311 m 2 / kg, a flowability ratio of 95%, a loss on ignition of 0.9%, and a 28d activity index of 80%.

[0039] Fine aggregate adopts natural sand produced by Xinjiang Zhongjian West Construction Building Material Co., Ltd., fineness modulus 2.6, particle size 0-5mm;

[0040] The water reducing agent adopted is polycarboxylic acid water reducing agent produced by Xinjiang Zhongjian West Construction New Material Technology Co., Ltd., water reducing rate 33%.

[0041] The dielectric constant tester adopts Japanese AET microwave (high frequency) dielectric constant tester (coaxial resonant cavity), testable frequency range: 800M-18GHz; dielectric constant Epsilon: 1-15, accuracy: ±1%, dielectric loss tangent delta: 0.1-0.001, accuracy: ±5%;

[0042] The phenolphthalein adopts phenolphthalein indicator produced by Maoming Xiongda Chemical Co., Ltd. Guangzhou Branch, purity 99.8%, density 1.296g / mL; the preparation steps of 1% alcohol phenolphthalein solution include: after 100g distilled water and 400g ethanol are mixed uniformly, 5g phenolphthalein is added into the mixture and mixed uniformly.

[0043] In the following examples, the steps of testing carbonation depth by phenolphthalein method include: splitting method or dry sawing method is used to break the mortar test piece on the pressure testing machine from one end; the thickness of each cut-off should be half of the width of the test piece, after cutting, the cut surface of the broken test piece is sealed with paraffin, and then the test piece is put into the box for continuous carbonation until the next test period; when a cubic test piece is used, the test piece is split in the middle, the cubic test piece should be tested only once, and cannot be reused after splitting and testing carbonation depth; then the test piece part obtained by cutting is brushed to remove the residual powder on the cut surface, and then 1% phenolphthalein alcohol solution (alcohol solution containing 20% distilled water) is sprayed (or dropped) on the cut surface; after about 30s, the carbonation depth of each point is measured by using a steel ruler according to the original marked measurement points, and then the average value of the carbonation depths of 10 measurement points is obtained to obtain carbonation depth II based on the phenolphthalein method.

[0044] Example 1

[0045] A detection method of carbonation depth of a cement-based material, comprising the following steps:

[0046] 1) Preparation of cement mortar carbonation test piece:

[0047] Take cement 4 kg, fly ash 2.6 kg, slag 1.2 kg and sand 15.7 kg respectively, pour into the mixer, add water 3.2 kg, water reducing agent 117 g, fully mix for 45 s, then pour out, put into a mold with size of 100 mm x 100 mm x 350 mm, vibrate on the vibration table for 15 s, then place in a room with temperature of 15-25℃ and humidity ≥50% for 24 hours, then take out and put into a standard curing with temperature of 18-22℃ and humidity ≥95% for 26 days, then take out and put into an oven with temperature of 60℃ for 48 h, after drying, except for one surface which should be left for carbonation test, the rest surfaces should be sealed with heated paraffin wax;

[0048] 2) Carbonation test of cement mortar test piece:

[0049] Put the cement mortar carbonation test piece obtained in step 1) into a carbonation test box, keep the carbon dioxide concentration in the box at 17-23%, the relative humidity at 65-75% and the temperature at 18-22℃ (during the carbonation test, monitor the carbon dioxide concentration, temperature and humidity in the box every certain period of time to ensure that the environment in the carbonation test box meets the requirements of the rapid carbonation test), and after reaching the specified carbonation age (3d, 7d, 14d and 28d), take the test piece out of the carbonation test box for subsequent carbonation depth detection;

[0050] 3) Test the dielectric constant of the cement test piece obtained in step 2) in an environment with temperature of 15-25℃ and humidity less than 80%: first remove the paraffin wax and other sealing materials on the side of the cement test piece; adjust the frequency of the dielectric constant tester to 0.6 GHz, and test the dielectric constant of the cement test piece from top to bottom along the carbonation depth direction at a probe moving rate of 8 mm / min, when the dielectric constant first decreases to below 5.3 (F / m) (specifically 5.1 F / m), take the depth value as the carbonation depth I based on the dielectric constant;

[0051] Test the carbonation depth II of the cement test piece of the carbonation age by phenolphthalein method;

[0052] 4) According to the obtained carbonation depth I and carbonation depth II, first eliminate data with error exceeding -10-10%, and then use the least square method to fit the two groups of data to establish the fitting equation of the carbonation depth I and the carbonation depth II.

[0053] The fitting results obtained by the method described in the embodiment are shown in Figure 1 ; the fitting equation is y=a+b*x, where y is the carbonation depth II by phenolphthalein method, x is the carbonation depth I based on the dielectric constant, a has a value range of 0.028-0.207; b has a value range of 0.943-0.950.

[0054] Application Example 1

[0055] A method for detecting carbonation depth of a cement-based material, specifically comprising the following steps:

[0056] The cement mortar test pieces of different carbonation ages were prepared according to the method described in steps 1) and 2) of Reference Example 1, and then the dielectric constant of the cement mortar test pieces of different carbonation ages at different depths was tested using a microwave (high frequency) dielectric constant tester (coaxial resonant cavity), wherein the test frequency of the dielectric constant tester was 1.1 GHz, and the probe moving speed was 10 mm / min; when the dielectric constant was first reduced to below 5.3 (F / m) (specifically 5.2 F / m), the depth was measured using a vernier caliper to obtain the dielectric constant carbonation depth; then the theoretical phenolphthalein method carbonation depth y was calculated according to the calculation model y = a + b * x (wherein a is 0.028, and b is 0.943) obtained in Example 1, and thus the carbonation depth value of the cement-based material was obtained.

[0057] The test results of the carbonation depth values (calculated carbonation depth) of the cement-based material corresponding to different carbonation ages obtained by the above method and the actual measured carbonation depth by the phenolphthalein method are shown in Table 1.

[0058] Table 1 Analysis results of carbonation depth obtained by the detection method described in Application Example 1

[0059]

[0060] The above results show that, by comparing the calculated phenolphthalein method carbonation depth with the actual measured phenolphthalein method carbonation depth, the error of the method of the present application is controlled within -6-4%, which proves that the calculation model of the present application has a very high fitting degree, and can quickly and directly obtain more accurate carbonation depth data through the calculation model.

[0061] Application Example 2

[0062] A method for detecting carbonation depth of a cement-based material, comprising the following steps:

[0063] The cement mortar test pieces of different carbonation ages were prepared according to the method described in steps 1) and 2) of Reference Example 1, and then the dielectric constant of the cement mortar test pieces of different carbonation ages at different depths was tested using a microwave (high frequency) dielectric constant tester (coaxial resonant cavity), wherein the test frequency of the dielectric constant tester was 1.1 GHz, and the probe moving speed was 10 mm / min; when the dielectric constant was first reduced to below 5.3 (F / m) (specifically 5.2 F / m), the depth was measured using a vernier caliper to obtain the dielectric constant carbonation depth; then the theoretical phenolphthalein method carbonation depth y was calculated according to the calculation model y = a + b * x (wherein a is 0.028, and b is 0.943) obtained in Example 1, and thus the carbonation depth value of the cement-based material was obtained.

[0057] The test results of the carbonation depth values (calculated carbonation depth) of the cement-based material corresponding to different carbonation ages obtained by the above method and the actual measured carbonation depth by the phenolphthalein method are shown in Table 1.

[0058] Table 1 Analysis results of carbonation depth obtained by the detection method described in Application Example 1

[0059]

[0060] The above results show that, by comparing the calculated phenolphthalein method carbonation depth with the actual measured phenolphthalein method carbonation depth, the error of the method of the present application is controlled within -6-4%, which proves that the calculation model of the present application has a very high fitting degree, and can quickly and directly obtain more accurate carbonation depth data through the calculation model.

[0061] Application Example 2

[0062] A method for detecting carbonation depth of a cement-based material, comprising the following steps:

[0063] The cement mortar test pieces of different carbonation ages were prepared according to the method described in steps 1) and 2) of Reference Example 1, and then the dielectric constant of the cement mortar test pieces of different carbonation ages at different depths was tested using a microwave (high frequency) dielectric constant tester (coaxial resonant cavity), wherein the test frequency of the dielectric constant tester was 1.1 GHz, and the probe moving speed was 10 mm / min; when the dielectric constant was first reduced to below 5.3 (F / m) (specifically 5.2 F / m), the depth was measured using a vernier caliper to obtain the dielectric constant carbonation depth; then the theoretical phenolphthalein method carbonation depth y was calculated according to the calculation model y = a + b * x (wherein a is 0.028, and b is 0.943) obtained in Example 1, and thus the carbonation depth value of the cement-based material was obtained.

[0064] The test results of the carbonation depth values (calculated carbonation depth) of the cement-based materials corresponding to different carbonation ages obtained by the above method and the actual carbonation depths measured by the phenolphthalein method are shown in Table 2.

[0065] Table 2 Analysis results of carbonation depths obtained by the detection method described in Example 2

[0066]

[0067] The above results show that, by comparing the calculated phenolphthalein method carbonation depth with the actual measured carbonation depth obtained by the phenolphthalein method, the error of the method of the present application is controlled within -4-6%, which proves that the calculation model obtained by the present application has a very high fitting degree, and can quickly and directly obtain more accurate carbonation depth data through the calculation model.

[0068] Example 3

[0069] A detection method of carbonation depth of a cement-based material, comprising the following steps:

[0070] The cement mortar test pieces of different carbonation ages are prepared by the methods described in steps 1) and 2) of Reference Example 1, and then the dielectric constant of the mortar test pieces at different depths is tested by using a microwave (high frequency) dielectric constant tester (coaxial resonant cavity), wherein the test frequency of the dielectric constant tester is 1.3 GHz, and the probe moving speed is 8 mm / min; when the dielectric constant is first reduced to below 5.3 (F / m) (specifically 5.3 F / m), the depth is measured by using a vernier caliper to obtain the dielectric constant carbonation depth; then the theoretical phenolphthalein method carbonation depth y is calculated according to the calculation model y=a+b*x (wherein a is 0.118, and b is 0.946) obtained in Example 1, and the carbonation depth value of the cement-based material is obtained.

[0071] The test results of the carbonation depth values (calculated carbonation depth) of the cement-based materials corresponding to different carbonation ages obtained by the above method and the actual carbonation depths measured by the phenolphthalein method are shown in Table 3.

[0072] Table 3 Analysis results of carbonation depths obtained by the detection method described in Example 3

[0073]

[0074] The above results show that, by comparing the calculated phenolphthalein method carbonation depth with the actual measured carbonation depth obtained by the phenolphthalein method, the error of the method of the present application is controlled within -5-3%, which proves that the calculation model obtained by the present application has a very high fitting degree, and can quickly and directly obtain more accurate carbonation depth data through the calculation model.

[0075] Comparative Example 1

[0076] A method for detecting carbonation depth of cement-based material, which is substantially the same as the steps of application example 1, except that the theoretical phenolphthalein method carbonation depth y is calculated according to the calculation model y = a + b * x (wherein a is 0.315, and b is 0.968); the specific test results are shown in Table 4.

[0077] Table 4 Analysis results of carbonation depth obtained by the detection method of comparative example 1

[0078]

[0079] The above results show that the detection error of the detection method of comparative document 1 is controlled at 12% or more, and the highest is 20%; and the high-efficiency detection of the carbonation depth of cement-based material cannot be achieved.

[0080] Comparative example 2

[0081] A method for detecting carbonation depth of cement-based material, comprising the following steps:

[0082] The cement mortar test pieces of different carbonation ages are prepared by the method described in steps 1) and 2) of reference example 1, and then the dielectric constant of the mortar test pieces at different depths is tested by using a microwave (high frequency) dielectric constant tester (coaxial resonant cavity), wherein the test frequency of the dielectric constant tester is 1.0 GHz, and the probe moving speed is 5 mm / min; taking the dielectric constant of 4.9 as the evaluation standard, when the dielectric constant is first reduced to below 4.9 (F / m) (specifically 4.8 (F / m)), the depth is measured by using a vernier caliper to obtain the carbonation depth I based on the dielectric constant; and then the theoretical phenolphthalein method carbonation depth y is calculated according to the calculation model y = a + b * x (wherein a is 0.028, and b is 0.943) obtained in example 1, so as to obtain the carbonation depth value of the cement-based material.

[0083] The test results of the carbonation depth values (calculated carbonation depth) of the cement-based material corresponding to different carbonation ages obtained by using the above method and the actual carbonation depth measured by the phenolphthalein method are shown in Table 5.

[0084] Table 5 Analysis results of carbonation depth obtained by the detection method of comparative example 2

[0085]

[0086] The above results show that the detection error of the detection method of comparative document 2 is controlled at 20% or more, and the highest is 38%; and the high-efficiency detection of the carbonation depth of cement-based material cannot be achieved.

[0087] The above embodiments are merely examples for clearly illustrating the made instances, but are not a limitation on the embodiments. Based on the above description, other different forms of changes or variations can also be made by those skilled in the art, and here, all the embodiments do not need to be exhausted, and the extended obvious changes or variations are still within the protection scope of the present application.

Claims

1. A method for detecting the carbonation depth of cement-based materials, characterized in that, Includes the following steps: 1) Cement specimen preparation: Prepare cement mortar, mold, demold, standard cure, dry, and obtain cement specimens; 2) Rapid carbonation test: The obtained cement specimens are placed in a rapid carbonation test chamber for rapid carbonation to different carbonation ages; 3) Carbonization depth detection: The dielectric constant of cement specimens with different carbonation ages obtained in step 2) is tested from top to bottom along the carbonation depth direction. When the dielectric constant changes significantly, the depth value is taken as the carbonation depth I based on the dielectric constant. The carbonation depth II of the cement specimen at this carbonation age was tested using the phenolphthalein method. 4) Based on the obtained carbonization depth I and carbonization depth II, the two sets of data are fitted using chemometric methods to establish the fitting equation between carbonization depth I and carbonization depth II.

2. The detection method according to claim 1, characterized in that, The standard curing conditions are as follows: place in a curing room with a temperature of 18-22℃ and a humidity of not less than 95% for 26-28 days; and dry at a temperature of 60-65℃ for 45-50 hours.

3. The detection method according to claim 1, characterized in that, The components and their weight percentages in the cement mortar include: 11-27 parts cement, 5-13 parts fly ash, 4-6 parts mineral powder, 49-60 parts sand, 10-13 parts water, and 0.4-1.0 parts water-reducing agent.

4. The detection method according to claim 1, characterized in that, Step 2) describes a rapid carbonization step using a carbon dioxide concentration of 17–23 vol%, a relative humidity of 65–75%, and a temperature of 18–22°C.

5. The detection method according to claim 1, characterized in that, The carbonization age can be selected from 3d, 7d, 14d and 28d.

6. The detection method according to claim 1, characterized in that, Step 3) The significant change in the dielectric constant is that it drops below 5.3 F / m for the first time, and the corresponding depth value relative to the concrete surface is the carbonation depth I.

7. The detection method according to claim 6, characterized in that, Step 3) The significant change in the dielectric constant is the first decrease to 5.3-5.0 F / m.

8. The detection method according to claim 1, characterized in that, The probe moving speed used in the dielectric constant test is 5-10 mm / min, and the test frequency is 0.5-1.3 GHz.

9. The detection method according to claim 1, characterized in that, The chemometric method is the least squares method.

10. The detection method according to claim 1, characterized in that, The carbonation depth I of the cement specimen to be tested is measured using the method corresponding to step 3). Then, the carbonation depth of the cement specimen to be tested is determined according to the fitting equation of the obtained carbonation depth I and carbonation depth II.

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