Method for determining the degree of reaction of waste clay brick powder in a cement hardened paste

Abstract

This invention discloses a method for determining the degree of reaction of waste clay brick powder in cement hardening slurry. The method mainly includes the following steps: first, preparation of a cement slurry test sample containing waste clay brick powder; second, energy dispersive spectroscopy (EDS) analysis and image capture of the cement slurry test sample containing waste clay brick powder; third, digital conversion of the brightness information from the EDS image of the cement slurry test sample containing waste clay brick powder; and fourth, calculation of the degree of reaction of waste clay brick powder in the cement slurry. This method is convenient to operate, has good repeatability, and can meet the needs of determining the degree of reaction of different types of waste clay brick powder in cement hardening slurry at different ages.

Description

Technical Field

[0001] This invention relates to a method for determining the degree of reaction of waste brick powder in cement materials, and more particularly to a method for determining the degree of reaction of waste clay brick powder in hardened cement paste. Background Technology

[0002] Waste clay brick powder is a recycled powder produced from waste clay bricks through crushing and grinding. Due to its low grinding power consumption and pozzolanic reactivity, waste clay brick powder has great potential as an auxiliary cementitious material and will be a major disposal method for waste clay brick construction solid waste in my country. Standards often use the activity index, i.e., the degree of reactivity, as an evaluation index for auxiliary cementitious materials. In hardened cement paste, the higher the degree of reactivity of the waste clay bricks, the higher the performance of the cement matrix containing the waste clay brick powder, and the higher the utilization value of the waste clay brick powder.

[0003] Currently, selective dissolution is the most commonly used method for evaluating the reactivity of auxiliary building cementitious materials. The principle of selective dissolution is based on the preferential solubility of cement hydration products and unhydrated cement particles in solvents such as acids, and the slight solubility or insolubility of auxiliary cementitious materials. By calculating the relationship between the mass of the dissolved residue and the mass of the undissolved sample, the reactivity of the auxiliary cementitious materials can be determined. The shortcomings of this method are: (1) the insolubility of calcium hydroxide and alite in cement hardened paste in solvents such as acids, thus affecting the calculation results; (2) the entire test requires multiple weighing, filtration, and drying procedures, and a large amount of manual operation will significantly affect the calculation results; (3) due to the large number of factors affecting the calculation results, the repeatability of the determination results of the reactivity of low-activity auxiliary cementitious materials is poor. Waste clay brick powder is classified as a slow-reacting pozzolanic material with low activity. Therefore, selective dissolution cannot effectively evaluate the reactivity of waste clay brick powder in cement hardened paste, which is not conducive to the evaluation of the activity performance of waste clay brick powder. Summary of the Invention

[0004] Purpose of the invention: The present invention aims to provide a method for accurately and conveniently testing the degree of reaction of waste clay brick powder in hardened cement paste.

[0005] Technical solution: The method for determining the degree of reaction of waste clay brick powder in cement hardening paste according to the present invention includes the following steps:

[0006] (1) Multiple slurry samples were obtained from cement hardening slurry containing waste clay brick powder at different locations. The slurry samples were then cold-mounted with epoxy resin and polished to obtain field emission scanning electron microscopy (FE-SEM) samples of cement hardening slurry containing waste clay brick powder.

[0007] (2) Perform energy dispersive spectroscopy analysis on the sample obtained in step (1), take pictures of the distribution of Ca, Si and Al elements, and determine the element content of Ca, Si and Al elements by energy dispersive spectral point scanning on the waste clay brick powder particles.

[0008] (3) Use a self-written program (the basic calculation principle is shown below) to convert the pixel brightness values ​​of the Ca, Si and Al element distribution images of the sample obtained in step (2) to obtain the image brightness digital matrix.

[0009] The basic calculation principle of the program: % is converted to brightness Y, which is grayscale, not 0-255.

[0010] %Y=0.2989*R+0.5870*G+0.1140*B;

[0011] Y=0.3334*R+0.3332*G+0.3333*B;

[0012] greyPic ​​= uint8(Y);

[0013] figure(2)

[0014] imshow(greyPic);

[0015] title('Convert RGB image to grayscale image')

[0016] (4) Calculate the ratio of Ca / Si and Ca / Al brightness values ​​at the same pixel position in the brightness digital matrix of the sample image obtained in step (3).

[0017] (5) Based on the energy spectrum point scanning element content results of the waste clay brick powder particles obtained in step (2), determine the Ca / Si and Ca / Al information ratios of the waste clay brick powder particles in the sample image obtained in step (2), and obtain the image digital matrix information that can generate waste clay brick powder particle markings.

[0018] (6) Convert the image digital matrix information of the waste clay brick powder particles obtained in step (5) into an image, calculate the area ratio of the waste clay brick particles in the above image, and calculate it using formula (1):

[0019]

[0020] In the formula, R RBP The degree of reaction of waste clay brick powder in cement hardening paste;

[0021] Af RBP (T=0) is the time when the curing age is 0. The area ratio of waste clay brick powder in the image of cement hardened slurry containing waste clay brick powder is calculated according to formula (2).

[0022] Af RBP (T=t) represents the area percentage of waste clay brick powder in the image of cement hardened slurry containing waste clay brick powder at time t, representing the curing age.

[0023] Furthermore, the volume ratio of waste clay brick powder in the cement paste before cement hydration is calculated using formula (2):

[0024]

[0025] In the formula: Af RBP (T=0) represents the volume fraction of waste clay brick powder;

[0026] ρ c This refers to the density of cement.

[0027] ρ w The density of the mixing water;

[0028] ρ B This refers to the density of waste clay brick powder.

[0029] M c This refers to the percentage of cement by mass.

[0030] M w The mass percentage of the mixing water;

[0031] M B This represents the mass percentage of the mixture.

[0032] Furthermore, the instrument used for the energy dispersive spectroscopy analysis is a field emission scanning electron microscope.

[0033] Technical principle:

[0034] The principle of this method is as follows: Based on the Ca, Si, and Al element distribution images of cement hardened paste containing waste clay brick powder obtained by field emission scanning electron microscopy, the waste clay brick powder particles in the above element distribution images are marked by digital conversion of the image brightness information and by limiting the Ca / Si and Ca / Al ratio conditions. Based on the area ratio of the waste clay brick powder particles in the image, the degree of reaction of the particles in the cement paste is calculated.

[0035] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages: (1) There are fewer human interference factors in the test process of this method. Field emission scanning electron microscope can provide the same energy spectrum analysis conditions, avoiding the influence of human factors on the test results; (2) The test results of this method are accurate and have good repeatability. By using field emission scanning electron microscopy energy spectrum analysis combined with a self-developed digital conversion program of image brightness information, the waste clay brick powder particles in the energy spectrum image of cement hardened slurry containing waste clay brick powder can be accurately identified, thereby accurately calculating the degree of reaction of waste clay brick powder in cement hardened slurry; (3) This method has a wide range of applications. It can be used to determine the degree of reaction of different types of waste clay brick powder in cement hardened slurry at different ages; (4) This method does not produce acid solvents or other substances that are harmful to the environment during the test process. Detailed Implementation

[0036] The technical solution of the present invention will be further described below with reference to the embodiments.

[0037] Example 1

[0038] 1. Degree of reaction of waste clay brick powder in PO cement hardened paste with a curing period of 3 days and a waste clay brick powder content of 30%.

[0039] 1.1 Five slurry samples were obtained from PO cement hardened slurry with a curing period of 3 days and a waste clay brick powder content of 30%. These slurry samples were cold-mounted using epoxy resin and then polished to obtain observation samples of cement hardened slurry containing waste clay brick powder.

[0040] 1.2 Energy dispersive spectroscopy (EDS) analysis was performed on these test samples using a field emission scanning electron microscope (FESEM). Five × 60 images of the distribution of Ca, Si, and Al elements were captured. The Ca, Si, and Al content of waste clay brick powder particles was determined by EDS point scanning. The pixel brightness values ​​of the obtained Ca, Si, and Al element distribution images were converted into image brightness digital matrices using a program. The Ca / Si and Ca / Al brightness ratios at the same positions in the image brightness digital matrices obtained from the Ca, Si, and Al element distribution images were calculated.

[0041] 1.3 Based on the energy dispersive spectral (EDS) results of the waste clay brick powder particles obtained in step (1.2) for Ca, Si, and Al elemental content, the Ca / Si and Ca / Al ratios of the brick powder particles in the EDS image of the cement hardened paste containing waste clay brick powder are determined, and image digital matrix information with waste clay brick powder particle markings is obtained. The obtained image digital matrix information with waste clay brick powder particle markings is then converted into an image.

[0042] 1.4 The area ratio of waste clay brick particles in the converted image obtained in step 1.3 was calculated using formulas (1) and (2), which yielded the reaction degree of waste clay brick powder in the PO cement hardened paste with a waste clay brick powder content of 30% after a curing period of 3 days. The results are shown in Tables 1 and 2.

[0043] Table 1 shows the reactivity of waste clay brick powder as provided by energy dispersive spectroscopy images of 20 random samples.

[0044]

[0045] Table 2. Reaction degree of waste clay brick powder in PO cement hardened paste with a curing period of 3 days and a waste clay brick powder content of 30%.

[0046]

[0047] Example 2

[0048] The degree of reaction of waste clay brick powder in PO cement hardened paste with a curing period of 28 days and a waste clay brick powder content of 30%.

[0049] 2.1 Five slurry samples were obtained from PO cement hardened slurry with a curing period of 28 days and a waste clay brick powder content of 30%. These slurry samples were cold-mounted using epoxy resin, and after polishing, energy dispersive spectroscopy (EDS) samples of the cement hardened slurry containing waste clay brick powder were obtained.

[0050] 2.2 Energy dispersive spectroscopy (EDS) analysis was performed on these test samples using a field emission scanning electron microscope (FESEM). Five × 60 images of the distribution of Ca, Si, and Al elements were captured. The Ca, Si, and Al content of waste clay brick powder particles was determined by EDS point scanning. The pixel brightness values ​​of the obtained Ca, Si, and Al element distribution images were converted into image brightness digital matrices using a program. The Ca / Si and Ca / Al brightness ratios at the same positions in the image brightness digital matrices obtained from the Ca, Si, and Al element distribution images were calculated.

[0051] 2.3 Based on the energy dispersive spectral (EDS) results of the waste clay brick powder particles obtained in step (1.2) for Ca, Si, and Al elemental content, the Ca / Si and Ca / Al ratios of the brick powder particles in the EDS image of the cement hardened paste containing waste clay brick powder are determined, and image digital matrix information with waste clay brick powder particle markings is obtained. The obtained image digital matrix information with waste clay brick powder particle markings is then converted into an image.

[0052] 2.4 Using formulas (1) and (2), the area ratio of waste clay brick particles in the converted image obtained in step (2.3) is calculated, and the reaction degree of waste clay brick powder in the PO cement hardened paste with a curing age of 28 days and a waste clay brick powder content of 30% is found to be 5.12%.

[0053] Example 3

[0054] The degree of reaction of waste clay brick powder in PO cement hardened paste with a curing period of 28 days and a waste clay brick powder content of 50%.

[0055] 3.1 Five slurry samples were obtained from PO cement hardened slurry with a curing period of 28 days and a waste clay brick powder content of 50%. These slurry samples were cold-mounted using epoxy resin, and after polishing, energy dispersive spectroscopy (EDS) samples of the cement hardened slurry containing waste clay brick powder were obtained.

[0056] 3.2 Energy dispersive spectroscopy (EDS) analysis was performed on these test samples using a field emission scanning electron microscope (FESEM). Five × 60 images of the distribution of Ca, Si, and Al elements were captured. The Ca, Si, and Al content of waste clay brick powder particles was determined by EDS point scanning. The pixel brightness values ​​of the obtained Ca, Si, and Al element distribution images were converted into image brightness digital matrices using a program. The Ca / Si and Ca / Al brightness ratios at the same positions in the image brightness digital matrices obtained from the Ca, Si, and Al element distribution images were calculated.

[0057] 3.3 Based on the energy dispersive spectral analysis (EDS) results of the waste clay brick powder particles obtained in step (3.2) for Ca, Si, and Al elemental content, the Ca / Si and Ca / Al ratios of the brick powder particles in the EDS image of the cement hardened paste containing waste clay brick powder are determined, and image digital matrix information with waste clay brick powder particle markings is obtained. The obtained image digital matrix information with waste clay brick powder particle markings is then converted into an image.

[0058] 3.4 Using formulas (1) and (2), the area ratio of waste clay brick particles in the converted image obtained in step (3.3) is calculated, and the reaction degree of waste clay brick powder in the PO cement hardened paste with a curing age of 28 days and a waste clay brick powder content of 30% is found to be 3.51%.

[0059] Example 4

[0060] The degree of reaction of waste clay brick powder in PI cement hardened paste with a curing period of 28 days and a waste clay brick powder content of 30%.

[0061] 4.1 Five slurry samples were obtained from PO cement hardened slurry with a curing period of 28 days and a waste clay brick powder content of 30%. These slurry samples were cold-mounted using epoxy resin, and after polishing, energy dispersive spectroscopy (EDS) samples of the cement hardened slurry containing waste clay brick powder were obtained.

[0062] 4.2 Energy dispersive spectroscopy (EDS) analysis was performed on these test samples using a field emission scanning electron microscope (FESEM). Five × 60 images of the distribution of Ca, Si, and Al elements were captured. The Ca, Si, and Al content of waste clay brick powder particles was determined by EDS point scanning. The pixel brightness values ​​of the obtained Ca, Si, and Al element distribution images were converted into image brightness digital matrices using a program. The Ca / Si and Ca / Al brightness ratios at the same positions in the image brightness digital matrices obtained from the Ca, Si, and Al element distribution images were calculated.

[0063] 4.3 Based on the energy dispersive spectral (EDS) results of the waste clay brick powder particles obtained in step (4.2) for Ca, Si, and Al elemental content, the Ca / Si and Ca / Al ratios of the brick powder particles in the EDS image of the cement hardened paste containing waste clay brick powder are determined, and image digital matrix information with waste clay brick powder particle markings is obtained. The obtained image digital matrix information with waste clay brick powder particle markings is then converted into an image.

[0064] 4.4 Using formulas (1) and (2), the area ratio of waste clay brick particles in the converted image obtained in step (4.3) is calculated, and the reaction degree of waste clay brick powder in the PO cement hardened paste with a curing age of 28 days and a waste clay brick powder content of 30% is found to be 5.43%.

Claims

1. A method for measuring the reaction degree of waste clay brick powder in a cement hardened paste, characterized by, Includes the following steps: (1) The cement hardened slurry containing waste clay brick powder was immersed in epoxy resin, hardened and polished to obtain the test sample; (2) Perform energy dispersive spectroscopy analysis on the above test samples to obtain the distribution images of Ca, Si and Al elements in the test samples; (3) Convert the pixel brightness values ​​of the distribution images of Ca, Si and Al elements in the test sample; (4) Calculate the ratio of Ca / Si and Ca / Al brightness values ​​of pixels at the same location in the Ca, Si and Al element distribution image; (5) Perform energy dispersive spectroscopy analysis on the waste clay brick powder particles to obtain the Ca, Si and Al element contents, thereby determining the Ca / Si and Ca / Al information numerical ratios of the waste clay brick powder in the cement hardened paste, obtaining the image digital information that can generate waste clay brick powder markings, and converting the above-obtained image digital information that can generate waste clay brick powder markings into images. (6) Calculate the area ratio of waste clay brick powder in the image obtained in step (5); (7) Based on the area ratio obtained in step (6), calculate the degree of reaction of the waste clay brick powder in the hardened cement paste according to formula (1): ； In the formula, is the reaction degree of the waste clay brick powder in the cement hardened paste; is the area ratio of the waste clay brick powder in the cement hardened paste picture at the curing age of 0; is the area ratio of the waste clay brick powder in the cement hardened paste picture at the curing age of t.

2. The method for determining the degree of reaction of waste clay brick powder in cement hardened slurry according to claim 1, characterized in that: In step (7) the Calculated as formula (2): ； is the density of the cement; is the density of the mixing water; is the density of the waste clay brick powder; is the mass percentage of the cement; is the mass percentage of the mixing water; is the mass percentage of the waste clay brick powder.

3. The method for determining the degree of reaction of waste clay brick powder in cement hardened slurry according to claim 1, characterized in that: The magnification of the distribution images of Ca, Si and Al elements in the test sample described in step (2) is 500 to 1000 times.

4. The method for determining the degree of reaction of waste clay brick powder in cement hardened slurry according to claim 1, characterized in that: The number of Ca, Si and Al element distribution images of the test sample in step (2) shall not be less than 5×60.

5. The method for determining the degree of reaction of waste clay brick powder in cement hardened slurry according to claim 1, characterized in that: The energy dispersive spectroscopy analysis was performed using a field emission scanning electron microscope.

6. The method for determining the degree of reaction of waste clay brick powder in cement hardened slurry according to claim 1, characterized in that: The test samples in step (1) were selected from different locations in cement hardened paste containing waste clay brick powder.

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