Nondestructive testing method for internal pore structure of foam light soil

Abstract

The invention discloses a nondestructive testing method for an internal pore structure of foam light soil, which is characterized by comprising the following steps of: 1, taking a cube foam light soil test piece with the side length of 40mm, placing the maintained test piece on a sample table, scanning around the test piece for a circle by using an X-CT (X-ray computed tomography) scanner, enabling X-rays to penetrate through different layers of the test piece, the detector receives attenuated information of different layers, the information is converted through software and then input into a computer for reconstruction, and a gray level image is obtained; and 2, Image-ProPlus analysis software is adopted to process the gray level image, a threshold value of the gray level image is automatically identified, a WatershedSplit algorithm of the Image-ProPlus analysis software is utilized to segment the automatically identified gray level image again, and then binarization processing is carried out on the segmented image. The method can realize nondestructive testing of the internal porosity, pore size distribution, pore shape factor and average pore size of the foam light soil, and is simple and convenient to operate, accurate in data, visual in result and high in practicability.

Description

Technical Field

[0001] The invention relates to the technical field of road materials, and in particular to a nondestructive detection method for the internal pore structure of foam lightweight soil. Background Art

[0002] Foam lightweight soil has the characteristics of lightness, fluidity, self-compactness, adjustable bulk density and strength, and convenient construction. As a new type of scientific and technological engineering material, it is widely used in the fields of widening roadbed, soft foundation embankment, bridge abutment backfill, rapid landslide rescue, etc. It can effectively solve the problems of settlement difference between new and old roadbeds, bridge culvert jumping in soft foundation embankment, and conventional filling occupying land resources. It can shorten the construction period, improve the quality of the project, and significantly reduce the maintenance cost after the project operation.

[0003] Foamed lightweight soil is a lightweight porous material formed by processing a foaming agent and an aqueous solution into foam through a foaming process, and then mixing it with a slurry liquid prepared using cement and other additives, and hardening it. Foamed lightweight soil has special properties due to its porous and large porosity. The porosity, pore size distribution, pore shape factor, and average pore size have a huge impact on strength and durability, especially the macro pores above 60μm have the greatest impact. Commonly used cement-based pore structure test methods such as adsorption method and mercury intrusion method (MIP) mainly focus on microscopic pores less than 60μm, which are not suitable for testing the pore structure of foamed lightweight soil. Optical microscopes or electron microscopes can analyze and test macroscopic pores above 60μm, but this method requires grinding the surface, which will destroy the specimen and cause damage to the internal pores. It also reflects only local information and is greatly affected by human operation. Summary of the invention

[0004] The purpose of this section is to summarize some aspects of embodiments of the present invention and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the specification abstract and the invention title of this application to avoid blurring the purpose of this section, the specification abstract and the invention title, and such simplifications or omissions cannot be used to limit the scope of the present invention.

[0005] In view of the problems existing in the above-mentioned existing non-destructive detection methods for the internal pore structure of foam lightweight soil, the present invention is proposed.

[0006] Therefore, the purpose of the present invention is to provide a method for nondestructive detection of the internal pore structure of foam lightweight soil, which can realize nondestructive detection of the internal porosity, pore size distribution, pore shape factor and average pore size of foam lightweight soil, and has the advantages of simple operation, accurate data, intuitive results and strong practicality.

[0007] In order to solve the above technical problems, the present invention provides the following technical solutions: a method for nondestructive detection of the internal pore structure of foamed lightweight soil, comprising the following steps:

[0008] Step 1: Take a cubic foam lightweight soil specimen with a side length of 40 mm, place the specimen on the sample table after curing, and use an X-CT scanner to scan around the specimen. The X-rays pass through different layers of the specimen, and the detector receives the attenuated information of different layers. After software conversion, it is input into the computer for reconstruction to obtain a grayscale image;

[0009] Step 2: Use Image-ProPlus analysis software to process the grayscale image, automatically identify the grayscale image threshold, use the WatershedSplit algorithm that comes with the Image-ProPlus analysis software to segment the automatically identified grayscale image again, and then perform binarization on the segmented image;

[0010] Step 3: Based on the binarized image, the internal porosity, pore size distribution, pore shape factor, and average pore size characteristics of the foam lightweight soil specimen are statistically analyzed, the pore structure data is exported, and the internal pore structure information of the foam lightweight soil is obtained.

[0011] As a preferred scheme of the nondestructive detection method of the internal pore structure of foam lightweight soil described in the present invention, wherein: in the step one, the size of the foam lightweight soil specimen is 40×40×40 mm, the X-CT technology consists of an X-ray scanner, a sample table and a detector, the voltage and current of the X-ray scanner are 0.3 mA and 195 kV respectively, and the number of detector pixels is 1024×1024 Pixel.

[0012] As a preferred solution of the nondestructive detection method of the internal pore structure of foam lightweight soil described in the present invention, wherein: in the step 2, the grayscale value range in the grayscale image is from 0 to 255, the Image-ProPlus analysis software is used to automatically identify the grayscale image threshold, and the WatershedSplit algorithm is used to re-segment the grayscale image to obtain a binary processed image, which effectively avoids the connectivity between pores.

[0013] As a preferred solution of the nondestructive detection method of the internal pore structure of foam lightweight soil described in the present invention, wherein: in the step three, the binary processed image is a picture that only contains grayscale values ​​0 and 255. Based on the binary processed image, the parameters to be measured - porosity, pore size distribution, pore shape factor, average pore size are selected, and data statistics are performed after export.

[0014] As a preferred scheme of the nondestructive detection method of the internal pore structure of foam lightweight soil described in the present invention, wherein: the pore diameter counted in the step three is divided into levels of 60μm-200μm, 200μm-300μm, 300μm-400μm, 400μm-500μm, 500μm-600μm, 600μm-700μm, 700μm-800μm, 800μm-900μm, 900μm-1000μm, 1000μm-1100μm, 1100μm-1200μm, 1200μm-1300μm, and 1300μm-1400μm to obtain a pore diameter distribution frequency histogram.

[0015] As a preferred scheme of the nondestructive detection method of the internal pore structure of the foam lightweight soil described in the present invention, wherein: in the step three, the pore shape factor is divided into levels of 1.0, 1.4, 1.8, 2.2, 2.6, 3.0, 3.4, and 3.8 to obtain a pore shape factor frequency histogram; the porosity is the percentage of the pore area to the total area, and the average pore size is the average value of all pores.

[0016] Beneficial effects of the invention: The invention designs a method for nondestructive detection of the internal pore structure of foam lightweight soil, which specifically targets macroscopic pores above 60 μm, evaluates porosity, pore size distribution, pore shape factor, and average pore size, and can realize nondestructive detection of the internal porosity, pore size distribution, pore shape factor, and average pore size of foam lightweight soil. The method is simple to operate, has accurate data, intuitive results, and is highly practical. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the following briefly introduces the drawings required for describing the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative labor. Among them:

[0018] Figure 1 The macroscopic cross-sectional images of foam lightweight soil with density grades of 600, 1000, and 1400;

[0019] Figure 2 Grayscale images of foam lightweight soil with density levels of 600, 1000, and 1400 after X-CT scanning;

[0020] Figure 3 The binary processed images were obtained for foam lightweight soil with density levels of 600, 1000, and 1400 after the WatershedSplit algorithm;

[0021] Figure 4 It is the pore size distribution frequency histogram of 600, 1000 and 1400 density levels;

[0022] Figure 5 The figure is the frequency histogram of the hole shape factor distribution for density levels of 600, 1000, and 1400. DETAILED DESCRIPTION

[0023] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are described in detail below in conjunction with the accompanying drawings.

[0024] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein, and those skilled in the art may make similar generalizations without violating the connotation of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed below.

[0025] Secondly, the term "one embodiment" or "embodiment" as used herein refers to a specific feature, structure, or characteristic that may be included in at least one implementation of the present invention. The term "in one embodiment" that appears in different places in this specification does not necessarily refer to the same embodiment, nor does it refer to a separate or selective embodiment that is mutually exclusive with other embodiments.

[0026] Secondly, the present invention is described in detail with reference to the schematic diagram. When describing the embodiments of the present invention in detail, for the sake of convenience, the cross-sectional diagrams showing the device structure will not be partially enlarged according to the general scale, and the schematic diagrams are only examples, which should not limit the scope of protection of the present invention. In addition, in actual production, the three-dimensional dimensions of length, width and depth should be included.

[0027] Reference Figure 1 - Figure 5 , provides a method for nondestructive detection of the internal pore structure of foam lightweight soil, characterized in that it includes the following steps:

[0028] Step 1: Take a cubic foam lightweight soil specimen with a side length of 40 mm, place the specimen on the sample table after curing, and use an X-CT scanner to scan around the specimen. The X-rays pass through different layers of the specimen, and the detector receives the attenuated information of different layers. After software conversion, it is input into the computer for reconstruction to obtain a grayscale image;

[0029] Step 2: Use Image-ProPlus analysis software to process the grayscale image, automatically identify the grayscale image threshold, use the WatershedSplit algorithm that comes with the Image-ProPlus analysis software to segment the automatically identified grayscale image again, and then perform binarization on the segmented image;

[0030] Step 3: Based on the binarized image, the internal porosity, pore size distribution, pore shape factor, and average pore size characteristics of the foam lightweight soil specimen are statistically analyzed, the pore structure data is exported, and the internal pore structure information of the foam lightweight soil is obtained.

[0031] Among them, in the step 1, the size of the foam lightweight soil specimen is 40×40×40 mm, and the X-CT technology consists of an X-ray scanner, a sample table and a detector. The voltage and current of the X-ray scanner are 0.3 mA and 195 kV respectively, and the number of detector pixels is 1024×1024 Pixel.

[0032] Specifically, in the step 2, the grayscale value range in the grayscale image is from 0 to 255, the grayscale image threshold is automatically identified by Image-ProPlus analysis software, and the grayscale image is segmented again using the WatershedSplit algorithm to obtain a binary processed image, thereby effectively avoiding the connectivity between pores.

[0033] Among them, in the step three, the binary processed image is a picture that only contains grayscale values ​​0 and 255. Based on the binary processed image, the parameters to be measured - porosity, pore size distribution, pore shape factor, average pore size - are selected and exported for data statistics.

[0034] Furthermore, the pore sizes counted in the step three are divided into levels of 60 μm to 200 μm, 200 μm to 300 μm, 300 μm to 400 μm, 400 μm to 500 μm, 500 μm to 600 μm, 600 μm to 700 μm, 700 μm to 800 μm, 800 μm to 900 μm, 900 μm to 1000 μm, 1000 μm to 1100 μm, 1100 μm to 1200 μm, 1200 μm to 1300 μm, and 1300 μm to 1400 μm to obtain a pore size distribution frequency histogram.

[0035] Among them, in the step three, the pore shape factor is divided into 1.0, 1.4, 1.8, 2.2, 2.6, 3.0, 3.4, and 3.8 levels to obtain a pore shape factor frequency histogram; the porosity is the percentage of the pore area to the total area, and the average pore size is the average value of all pores.

[0036] Example: The Technical Specification for Cast-in-place Foam Lightweight Soil (CECS249-2008) specifies the density range of foam lightweight soil from 300 to 1600 kg / m 3 In this embodiment, representative foam lightweight soils with density levels of 600, 1000, and 1400 are selected for further explanation. Foam lightweight soils with density levels of 600, 1000, and 1400 are configured according to the mix ratio in Table 1, and the water-binder ratio is 0.33.

[0037] Table 1 Mix design and results of foam lightweight soil at different density levels

[0038]

[0039] 1) Grayscale image

[0040] Taking foam lightweight soil with density levels of 600, 1000, and 1400 as an example, the macroscopic cross-sectional images of foam lightweight soil with three density levels are shown in the figure. Figure 1 The grayscale image obtained by using the X-CT detector is shown in Figure 2 As shown, the grayscale image is composed of grayscale values ​​of 0 to 255.

[0041] 2) Binarization of the image

[0042] The binary processed image was obtained by the WatershedSplit algorithm in the Image-ProPlus analysis software, such as Figure 3 shown.

[0043] 3) Porosity and average pore size

[0044] According to the statistics of Image-ProPlus analysis software, the porosity of foamed lightweight soil with density levels of 600, 1000, and 1400 is 56.8%, 39.4%, and 16.2%, respectively, and the porosity decreases with the increase of density level. The average pore size of foamed lightweight soil with density levels of 600, 1000, and 1400 is 650μm, 460μm, and 370μm, respectively, and the average pore size decreases with the increase of density level, as shown in Table 1.

[0045] 4) Pore size distribution and pore shape factor

[0046] According to the statistics of Image-ProPlus analysis software, the pore size distribution frequency histogram of foam lightweight soil with density levels of 600, 1000, and 1400 is as follows: Figure 4 The pore shape factor distribution frequency histogram of foam lightweight soil with density levels of 600, 1000, and 1400 is shown in Figure 5 shown.

[0047] It can be seen that the present invention can realize non-destructive quantitative detection of foam lightweight soil without destroying the material during the entire testing process.

[0048] It should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present invention may be modified or replaced by equivalents without departing from the spirit and scope of the technical solutions of the present invention, which should all be included in the scope of the claims of the present invention.

Claims

1. A nondestructive testing method for the internal pore structure of foamed lightweight soil, characterized in that: The following steps are involved: Step 1: Take a cubic foam lightweight soil specimen with a side length of 40 mm, place the specimen on the sample table after curing, and use an X-CT scanner to scan around the specimen. The X-rays pass through different layers of the specimen, and the detector receives the attenuated information of different layers. After software conversion, it is input into the computer for reconstruction to obtain a grayscale image; Step 2: Use Image-ProPlus analysis software to process the grayscale image, automatically identify the grayscale image threshold, use the WatershedSplit algorithm that comes with the Image-ProPlus analysis software to segment the automatically identified grayscale image again, and then perform binarization on the segmented image; Step 3: Based on the binarized image, the internal porosity, pore size distribution, pore shape factor, and average pore size characteristics of the foam lightweight soil specimen are statistically analyzed, the pore structure data is exported, and the internal pore structure information of the foam lightweight soil is obtained.

2. The nondestructive testing method for the internal pore structure of foamed lightweight soil according to claim 1 is characterized in that: In the step 1, the size of the foam lightweight soil specimen is 40×40×40 mm, and the X-CT technology is composed of an X-ray scanner, a sample stage and a detector. The voltage and current of the X-ray scanner are 0.3 mA and 195 kV respectively, and the number of detector pixels is 1024×1024 Pixel.

3. The nondestructive testing method for the internal pore structure of foamed lightweight soil according to claim 2 is characterized in that: In the step 2, the grayscale value range in the grayscale image is from 0 to 255, and the grayscale image threshold is automatically identified by Image-ProPlus analysis software, and the grayscale image is segmented again using the WatershedSplit algorithm to obtain a binary processed image, thereby effectively avoiding the connection phenomenon between the holes.

4. The nondestructive testing method for the internal pore structure of foamed lightweight soil according to claim 1 is characterized in that: In step three, the binary processed image is a picture containing only grayscale values ​​of 0 and 255. Based on the binary processed image, the parameters to be measured - porosity, pore size distribution, pore shape factor, average pore size - are selected and exported for data statistics.

5. The nondestructive testing method for the internal pore structure of foamed lightweight soil according to claim 4 is characterized in that: The pore sizes counted in the step three are divided into levels of 60 μm to 200 μm, 200 μm to 300 μm, 300 μm to 400 μm, 400 μm to 500 μm, 500 μm to 600 μm, 600 μm to 700 μm, 700 μm to 800 μm, 800 μm to 900 μm, 900 μm to 1000 μm, 1000 μm to 1100 μm, 1100 μm to 1200 μm, 1200 μm to 1300 μm, and 1300 μm to 1400 μm to obtain a pore size distribution frequency histogram.

6. The nondestructive testing method for the internal pore structure of foamed lightweight soil according to claim 1, characterized in that: In the step three, the pore shape factor is divided into 1.0, 1.4, 1.8, 2.2, 2.6, 3.0, 3.4, and 3.8 levels to obtain a pore shape factor frequency histogram; the porosity is the percentage of the pore area to the total area, and the average pore size is the average value of all pores.

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