Method for identifying machine-made sand, river sand and sea sand

Abstract

The invention belongs to the technical field of detection and analysis, and discloses a machine-made sand, river sand and sea sand identification method which comprises the following steps: drying a sand particle sample, and cooling to room temperature for later use; inlaying the sand particles with a conductive cold inlaying material to obtain an inlayed sand particle sample; carrying out mechanical polishing on the sand particle sample; collecting a color image of the sand particles; preprocessing the color image; calculating the circularity of each sand particle in the sand particle contour binary image data; respectively testing to obtain saturated surface dry water absorption, shell content and chloride content of the sand particle sample; putting the sand particle sample into a drying oven, drying to constant weight, cooling, and grinding by using a ball mill; testing the powder to obtain the total chlorine ion content of the sample; and identifying the sand type according to the obtained circularity, saturated surface dry water absorption, shell content, chloride content and total chloride ion content. According to the invention, rapid, accurate and quantifiable identification can be carried out.

Description

Technical Field

[0001] The invention relates to the technical field of detection and analysis, and in particular to a method for identifying machine-made sand, river sand and sea sand. Background Art

[0002] Sand and gravel are one of the most important raw materials in the concrete and mortar industry. In recent years, driven by the rapid development of the national economy and infrastructure construction, there is a strong demand for sand and gravel materials. Natural sand resources, especially river sand, are becoming increasingly scarce, and machine-made sand has gradually replaced natural sand to become the mainstream of the development of the sand and gravel industry. However, in actual projects, the quality of most machine-made sand is not satisfactory, and there are often deficiencies such as particle grading and excessive needle-like content, which often affect the workability of concrete. Therefore, in concrete production, producers often add some natural sand to machine-made sand to improve the workability of concrete. However, due to the high price of natural sand such as river sand, a few coastal concrete producers often add some desalinated sea sand or desalinated unqualified sea sand to machine-made sand in order to reduce production costs.

[0003] Therefore, it is very important to develop an analytical method that can quickly, scientifically and quantitatively identify machine-made sand, sea sand and river sand. Summary of the invention

[0004] In view of the problems existing in the prior art, the purpose of the present invention is to provide a quantitative analysis method for distinguishing machine-made sand, river sand and sea sand. By collecting parameters such as particle roundness, saturated surface dry water absorption, shell content, total chloride ion content, chloride content and other parameters of various sand samples, the value ranges of the relevant parameters of various sands are established, and a quantifiable identification and analysis method for various sands is established.

[0005] To achieve the above object, the present invention provides the following technical solutions:

[0006] A method for identifying machine-made sand, river sand and sea sand, characterized in that it comprises the following steps:

[0007] Step 1, placing the sand particle sample in an oven and drying it to constant weight, cooling it to room temperature for later use; using a conductive cold mounting material to mount the sand particles to obtain a mounted sand particle sample;

[0008] Step 2, mechanically polishing the mounted sand particle sample obtained in step 1 to obtain a mechanically polished sand particle cross-section sample having a smooth and scratch-free sand particle cross-section;

[0009] Step 3, placing the polished sand particle sample obtained in step 2 under a stereo microscope to observe the contour of the sand particles, and using a digital camera device to record a color image of the sand particles;

[0010] Step 4, preprocessing the color image of the sand particles obtained in step 3, first converting the color image of the sand particles into a grayscale image, and then binarizing the grayscale image of the sand particles to obtain a binary image of the sand particle contour with clear contours and no overlap;

[0011] Step 5, calculating the circularity of each sand particle in the sand particle contour binary image data obtained in step 4, and calculating the average value thereof. The circularity is calculated according to the following formula:

[0012]

[0013] in, C represents the circularity, L represents the projected circumference of the sand particle, and A represents the projected area of ​​the sand particle;

[0014] Step 6, respectively testing and obtaining the saturated surface dry water absorption rate, shell content and chloride content of the sand particle sample;

[0015] Step 7, drying the sand particle sample in an oven to constant weight, and grinding it in a ball mill after cooling;

[0016] Step 8, testing the powder obtained in step 7 to obtain the total chloride ion content of the sample;

[0017] Step 9, substitute the values ​​of roundness, saturated surface dry water absorption, shell content, chloride content and total chloride ion content obtained in steps 5, 6 and 8 into the following process to identify the type of sand:

[0018] Step 9.1, identify the sand type based on the average value of the sand particle circularity Caverage:

[0019] When Caverage ≥ 0.88, the sand sample to be tested is non-machine-made sand;

[0020] When Caverage≤0.75, the sand sample to be tested is machine-made sand;

[0021] When 0.75<Caverage<0.88, it is necessary to proceed to step 9.2 to identify the type of sand based on the saturated surface dry water absorption rate of the sand particle sample to be tested;

[0022] Step 9.2, identify the sand type based on the saturated surface dry water absorption rate:

[0023] When the saturated surface dry water absorption rate is greater than 1.23%, the sand sample to be tested is machine-made sand;

[0024] When the saturated surface dry water absorption rate is less than 0.74%, the sand sample to be tested is natural sand (sea sand, river sand). The identification of non-mechanical sand requires the combination of shell content, total chloride ion content, water-soluble chloride ion content and other indicators, so go to step 9.3;

[0025] Step 9.3, identify the sand type based on shell content and total chloride ion content:

[0026] When the sand particle sample does not contain shells and the total chloride ion content is less than 0.005%, the sand particle sample to be tested is river sand;

[0027] When the sand particle sample contains shells and the total chloride ion content is greater than 0.01%, the sand particle sample to be tested is desalinated sea sand or non-desalinated sea sand. To distinguish desalinated sea sand from non-desalinated sea sand, the water-soluble chloride ion content index of the sand sample is required, so go to step 9.4;

[0028] Step 9.4, identify the sand type based on the water-soluble chloride ion content:

[0029] When the water-soluble chloride ion content is greater than 0.06%, the sand particle sample to be tested is unsalted sea sand;

[0030] When the water-soluble chloride ion content is ≤0.06%, the sand particle sample to be tested is desalinated sea sand.

[0031] Furthermore, the conductive cold mounting material in step 1 comprises the following components in parts by weight: 50-80 parts of conventional uncured cold mounting material and 20-50 parts of copper powder.

[0032] Furthermore, in step 1, the drying temperature of the sand particle sample is 100°C-110°C.

[0033] Furthermore, step 6 specifically includes: testing the saturated surface dry water absorption, shell content and chloride content of the sand particle sample in accordance with parts 7.21, 7.12 and 7.11 of GB / T 14684-2022 "Construction Sand".

[0034] Furthermore, in step 7, the drying temperature of the sand particle sample is 100° C.-110° C., and the ground powder sample must be able to completely pass through a square hole sieve with a pore size of 45 μm.

[0035] Furthermore, step 8 specifically includes: testing the powder obtained in step 7 according to section 6.13 of GB / T176-2017 "Chemical Analysis Methods for Cement" to obtain the total chloride ion content of the sample.

[0036] Compared with the prior art, the beneficial effects of the present invention are: the present invention creatively integrates indicators such as roundness, saturated surface dry water absorption, shell content, total chloride ion content, water-soluble chloride ion content, etc., and establishes a set of identification methods for machine-made sand, river sand, and sea sand, which can perform fast, accurate, and quantifiable identification. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] Figure 1 It is a flow chart of the present invention.

[0038] Figure 2 This is a flow chart of step 9 in the present invention. DETAILED DESCRIPTION

[0039] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0040] Example 1

[0041] See also Figure 1 A method for identifying machine-made sand, river sand and sea sand comprises the following steps:

[0042] Step 1: Place the sand particle sample in an oven and dry it to constant weight at 100°C-110°C, and cool it to room temperature for later use. Use a conductive cold mounting material to mount the sand particles to obtain a mounted sand particle sample.

[0043] The conductive cold mounting material comprises the following components in parts by weight: 50-80 parts of conventional uncured cold mounting material and 20-50 parts of copper powder.

[0044] Step 2: Mechanically polishing the mounted sand particle sample obtained in step 1 to obtain a mechanically polished sand particle cross-section sample having a smooth and scratch-free sand particle cross-section.

[0045] Step 3: Place the polished sand particle sample obtained in step 2 under a stereo microscope to observe the contour of the sand particles, and use a digital camera to record the color image of the sand particles.

[0046] Step 4, preprocessing the color image of the sand particles obtained in step 3, first converting the color image of the sand particles into a grayscale image, and then binarizing the grayscale image of the sand particles to obtain a binary image of the sand particle contours with clear contours and no overlap.

[0047] Step 5, calculating the circularity of each sand particle in the sand particle contour binary image data obtained in step 4, and calculating the average value thereof. The circularity is calculated according to the following formula:

[0048]

[0049] in, C represents the circularity, L represents the projected circumference of the sand particle, and A represents the projected area of ​​the sand particle.

[0050] Step 6: According to Sections 7.21, 7.12, and 7.11 of GB / T 14684-2022 "Construction Sand", the saturated surface dry water absorption, shell content, and chloride content of the sand particle samples are tested respectively.

[0051] Step 7, place the sand particle sample in an oven and dry it to constant weight. The drying temperature of the sand particle sample is 100°C-110°C. After cooling, the sand particle sample is ground using a ball mill. The ground powder sample must be able to completely pass through a square hole sieve with a pore size of 45 μm.

[0052] Step 8: Test the powder obtained in step 7 according to section 6.13 of GB / T 176-2017 "Chemical Analysis Methods for Cement" to obtain the total chloride ion content of the sample.

[0053] Step 9, such as Figure 2 As shown, the values ​​of roundness, saturated surface dry water absorption, shell content, chloride content and total chloride ion content obtained in step 5, step 6 and step 8 are substituted into the following process to identify the type of sand:

[0054] Step 9.1, identify the sand type based on the average value of the sand particle circularity Caverage:

[0055] When Caverage ≥ 0.88, the sand sample to be tested is non-machine-made sand;

[0056] When Caverage≤0.75, the sand sample to be tested is machine-made sand;

[0057] When 0.75<Caverage<0.88, it is necessary to proceed to step 9.2 and identify the type of sand based on the saturated surface dry water absorption rate of the sand particle sample to be tested.

[0058] Step 9.2, identify the sand type based on the saturated surface dry water absorption rate:

[0059] When the saturated surface dry water absorption rate is greater than 1.23%, the sand sample to be tested is machine-made sand;

[0060] When the saturated surface dry water absorption rate is less than 0.74%, the sand sample to be tested is natural sand (sea sand, river sand). The identification of non-mechanical sand requires the combination of indicators such as shell content, total chloride ion content, and water-soluble chloride ion content, so proceed to step 9.3.

[0061] When 0.74%≤saturated surface dry water absorption≤1.23%, this possibility is extremely small and difficult to identify, so no judgment is made.

[0062] Step 9.3, identify the sand type based on shell content and total chloride ion content:

[0063] When the sand particle sample does not contain shells and the total chloride ion content is less than 0.005%, the sand particle sample to be tested is river sand;

[0064] When the sand particle sample contains shells and the total chloride ion content is greater than 0.01%, the sand particle sample to be tested is desalinated sea sand or non-desalinated sea sand. To distinguish between desalinated sea sand and non-desalinated sea sand, the water-soluble chloride ion content index of the sand sample is required, so proceed to step 9.4.

[0065] When 0.005%≤total chloride ion content≤0.01%, this possibility is extremely small and difficult to identify, so no judgment is made.

[0066] Step 9.4, identify the sand type based on the water-soluble chloride ion content:

[0067] When the water-soluble chloride ion content is greater than 0.06%, the sand particle sample to be tested is unsalted sea sand;

[0068] When the water-soluble chloride ion content is ≤0.06%, the sand particle sample to be tested is desalinated sea sand.

[0069] Example 2

[0070] Materials needed for the experiment:

[0071] a) Chemical reagents: analytically pure silver nitrate, potassium chromate, ammonium ferric sulfate, and nitric acid, all produced by Sinopharm Chemical Reagent Co., Ltd.;

[0072] b) Cold mounting material: CM7, produced by Hangzhou Jingjing Testing Instrument Co., Ltd.;

[0073] c) Copper powder: produced by Hangzhou Jingjing Testing Instrument Co., Ltd.

[0074] d) Implementation of sand samples: Six sand samples were collected (two machine-made sands, two river sands, and two desalinated sea sands), as shown in Table 1:

[0075] Table 1 Statistics of sand sources and types

[0076]

[0077] The sand samples numbered 1-6 were pre-treated according to step 1 and step 2 in Example 1, and the circularity of each sand sample was obtained according to step 3 to step 5 in Example 1, as shown in Table 2:

[0078] Table 2 Statistics of roundness of sample sand

[0079]

[0080] Substitute the values ​​in Table 2 into Figure 2 The identification method flow can get the identification results in Table 3:

[0081] Table 3 Sample sand type determination (roundness)

[0082]

[0083] According to step 6 in Example 1, the shell content, total chloride ion and water-soluble chloride ion content of the sand samples numbered 2, 3, 4 and 5 were tested and analyzed, and the values ​​are shown in Table 4:

[0084] Table 4 Summary of sample shell content, total chloride ion content, and water-soluble chloride ion content

[0085]

[0086] Substitute the values ​​in Table 4 into Figure 1 The identification results in Table 5 can be obtained by following the process:

[0087] Table 5 Determination of sample 1-5 types (shell content, total chloride ion, water-soluble chloride ion content index)

[0088]

[0089] Combining the results in Table 3 and Table 5, we can get the judgment results in Table 6:

[0090] Table 6 Sand sample type identification results

[0091]

[0092] The identification result is consistent with the actual situation, indicating that this method is accurate and effective.

[0093] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for identifying machine-made sand, river sand and sea sand, characterized in that: The following steps are involved: Step 1, placing the sand particle sample in an oven and drying it to constant weight, cooling it to room temperature for later use; using a conductive cold mounting material to mount the sand particles to obtain a mounted sand particle sample; Step 2, mechanically polishing the mounted sand particle sample obtained in step 1; Step 3, placing the polished sand particle sample obtained in step 2 under a stereo microscope to observe the contour of the sand particles, and using a digital camera device to record a color image of the sand particles; Step 4, preprocessing the color image of the sand particles obtained in step 3, first converting the color image of the sand particles into a grayscale image, and then binarizing the grayscale image of the sand particles to obtain a binary image of the sand particle contour; Step 5, calculating the circularity of each sand particle in the sand particle contour binary image data obtained in step 4, and calculating the average value thereof. The circularity is calculated according to the following formula: in, C represents the circularity, L represents the projected circumference of the sand particle, and A represents the projected area of ​​the sand particle; Step 6, respectively testing and obtaining the saturated surface dry water absorption rate, shell content and chloride content of the sand particle sample; Step 7, drying the sand particle sample in an oven to constant weight, and grinding it in a ball mill after cooling; Step 8, testing the powder obtained in step 7 to obtain the total chloride ion content of the sample; Step 9, substitute the values ​​of roundness, saturated surface dry water absorption, shell content, chloride content and total chloride ion content obtained in steps 5, 6 and 8 into the following process to identify the type of sand: Step 9.1, identify the sand type based on the average value of the sand particle circularity Caverage: When Caverage ≥ 0.88, the sand sample to be tested is non-machine-made sand; When Caverage≤0.75, the sand sample to be tested is machine-made sand; When 0.75<Caverage<0.88, it is necessary to proceed to step 9.2 to identify the type of sand based on the saturated surface dry water absorption rate of the sand particle sample to be tested; Step 9.2, identify the sand type based on the saturated surface dry water absorption rate: When the saturated surface dry water absorption rate is greater than 1.23%, the sand sample to be tested is machine-made sand; When the saturated surface dry water absorption rate is less than 0.74%, the sand sample to be tested is natural sand, and the procedure goes to step 9.3; Step 9.3, identify the sand type based on shell content and total chloride ion content: When the sand particle sample does not contain shells and the total chloride ion content is less than 0.005%, the sand particle sample to be tested is river sand; When the sand particle sample contains shells and the total chloride ion content is greater than 0.01%, the sand particle sample to be tested is desalinated sea sand or undesalinated sea sand, and the procedure goes to step 9.4; Step 9.4, identify the sand type based on the water-soluble chloride ion content: When the water-soluble chloride ion content is greater than 0.06%, the sand particle sample to be tested is unsalted sea sand; When the water-soluble chloride ion content is ≤0.06%, the sand particle sample to be tested is desalinated sea sand.

2. A method for identifying machine-made sand, river sand and sea sand according to claim 1, characterized in that: The conductive cold mounting material in step 1 comprises the following components in parts by weight: 50-80 parts of cold mounting material and 20-50 parts of copper powder.

3. The method for identifying machine-made sand, river sand and sea sand according to claim 1, characterized in that: The drying temperature of the sand particle sample in step 1 is 100° C.-110° C.

4. The method for identifying machine-made sand, river sand and sea sand according to claim 1, characterized in that: The step 6 specifically includes: testing the saturated surface dry water absorption, shell content and chloride content of the sand particle sample in accordance with parts 7.21, 7.12 and 7.11 of GB / T 14684-2022 "Construction Sand".

5. The method for identifying machine-made sand, river sand and sea sand according to claim 1, characterized in that: In step 7, the drying temperature of the sand particle sample is 100° C.-110° C., and the ground powder sample must be able to completely pass through a square hole sieve with a pore size of 45 μm.

6. The method for identifying machine-made sand, river sand and sea sand according to claim 1, characterized in that: The step 8 specifically includes: testing the powder obtained in step 7 according to section 6.13 of GB / T 176-2017 "Chemical Analysis Methods for Cement" to obtain the total chloride ion content of the sample.

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