CN110823890A - Method for determining carbonization depth of recycled concrete - Google Patents
Method for determining carbonization depth of recycled concrete Download PDFInfo
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- CN110823890A CN110823890A CN201911050432.2A CN201911050432A CN110823890A CN 110823890 A CN110823890 A CN 110823890A CN 201911050432 A CN201911050432 A CN 201911050432A CN 110823890 A CN110823890 A CN 110823890A
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Abstract
The invention discloses a method for determining the carbonization depth of recycled concrete, which comprises the following steps: coating an indicator on the fracture surface of the carbonized recycled concrete test piece after fracture, and distinguishing a carbonization zone from a non-carbonization zone; shooting the fracture surface of the test piece with the carbonization zone and the non-carbonization zone distinguished; and converting the shot picture into a vector diagram through an image digitization tool, performing digital representation on points on a boundary line of a carbonization area and a non-carbonization area in the vector diagram, acquiring carbonization depth values of the points, and taking the maximum value as the carbonization depth of the recycled concrete. The method adopts an image digitization tool to digitize the point data on the boundary line between the carbonization area and the non-carbonization area of the carbonized and regenerated concrete, thereby directly reading the carbonization depth data, being simple and easy to operate, reducing the human error and improving the test efficiency; the maximum value in the carbonization depths is used as the carbonization depth of the recycled concrete, so that the carbonization service life of the reinforced concrete structure containing the recycled concrete can be accurately predicted, and the safety of the reinforced concrete structure is improved.
Description
Technical Field
The invention relates to a method for determining the carbonization depth of recycled concrete, belonging to the field of building material detection.
Background
The application of the recycled concrete in the field of buildings can reduce the pollution of construction waste to the environment and can relieve the requirements of the construction industry on natural gravels. Because a part of old mortar is attached to the recycled aggregate, there are two types of mortar in the recycled concrete: new mortar and old mortar. Due to the fact thatThe new mortar and the old mortar have different microstructures, and when the recycled concrete is exposed to air, CO is generated2Will be transported in the new mortar and the old mortar, respectively, at two speeds, so the carbonization depth of the new mortar and the old mortar will be different. When the porosity of the old mortar is lower than that of the new mortar, the carbonization depth of the old mortar is smaller than that of the new mortar; when the porosity of the old mortar is higher than that of the new mortar, the carbonization depth of the old mortar is greater than that of the new mortar.
Because only one mortar exists in the common concrete, namely theoretically, only one carbonization depth exists in the common concrete, the conventional method for testing the carbonization depth of the common concrete is to calculate the average value. GB/T50082-2009 Standard test method for the long-term performance and durability of ordinary concrete stipulates: before carbonization, parallel lines are drawn on the exposed side surface of the concrete sample along the length direction by a pencil at intervals of 10mm, after carbonization, the concrete is split, phenolphthalein alcohol solution is sprayed, after a period of time, the carbonization depth of each point is measured by a steel plate ruler according to one measuring point of every 10mm marked originally, and the average value is the carbonization depth.
On one hand, the testing method has large influence on manual operation, can cause large errors, and is complicated to operate; on the other hand, the carbonization depth of the recycled concrete defined by the determination standard of the carbonization depth of the common concrete does not meet the actual carbonization condition of the recycled concrete, so that the relative standard error and the average relative error in the calculation process are large, and the method cannot be used for service life calculation and evaluation in actual engineering.
Disclosure of Invention
The purpose of the invention is as follows: the invention provides a method for determining the carbonization depth of recycled concrete, aiming at the problems that the existing common concrete carbonization depth determination method has large error and is complicated to operate and is not in line with the actual condition of the carbonization of the recycled concrete.
The technical scheme is as follows: the invention discloses a method for determining the carbonization depth of recycled concrete, which comprises the following steps:
step 1, coating an indicator on a fracture surface of a broken carbonized recycled concrete test piece, and distinguishing a carbonized area from a non-carbonized area;
and 3, converting the shot picture into a vector diagram through an image digitization tool, performing digital representation on points on a boundary line of a carbonization area and a non-carbonization area in the vector diagram, obtaining the carbonization depth value of each point, and taking the maximum value as the carbonization depth of the recycled concrete.
In the step 1, the shape breaking method of the carbonized recycled concrete test piece may be cutting or splitting, and preferably, a dry sawing method, a splitting method on a pressure tester or other methods are adopted to start the shape breaking from one end of the test piece. The indicator can be phenolphthalein alcohol solution, preferably 1% phenolphthalein alcohol solution (20% distilled water in alcohol solution). And after the indicator is coated, waiting for 10-20 min to enable the indicator to develop color and volatilize alcohol, wherein a color-changing area on a fracture surface of the test piece is a carbonization area, and an uncolored area is a non-carbonization area, so that the carbonization area and the non-carbonization area can be distinguished.
Preferably, in the step 2, when the fracture surface of the test piece is photographed, the photographing lens is ensured to be parallel to the fracture surface of the test piece, so that the length-width ratio of the fracture surface of the photo is ensured to be consistent with the length-width ratio of the actual fracture surface, and the test precision is improved.
In step 3, the image digitizing tool may be GetData Graph Digitizer software. The method for converting the shot photo into the vector diagram by adopting the image digitization tool comprises the following steps: opening the shot photos by adopting an image digitization tool, establishing coordinate axes along the edges of the fracture surfaces of the recycled concrete test piece by taking the carbonization direction as an X axis and the direction orthogonal to the X axis as a Y axis in the image digitization tool, respectively representing the length and the width in the photos by taking the actual length and the width of the fracture surfaces, and converting the shot photos into vector diagrams; the abscissa value of each point on the boundary line of the carbonization area and the non-carbonization area in the vector diagram in the coordinate axis is the carbonization depth value of each point.
Has the advantages that: compared with the prior art, the invention has the advantages that: (1) the method adopts an image digitization tool to convert the picture of the fracture surface of the carbonized recycled concrete into a vector diagram, and converts the boundary line between the color-changing area and the non-color-changing area of the indicator into data, so that when the carbonization depth data is read, manual reading is avoided, the human error can be effectively reduced, and the test efficiency is improved; (2) the invention creatively adopts the maximum value in the carbonization depth as the carbonization depth of the recycled concrete, and can accurately predict the carbonization service life of the reinforced concrete structure containing the recycled concrete, thereby improving the safety of the reinforced concrete structure.
Drawings
FIG. 1 is a schematic diagram of the extraction and statistics of recycled concrete carbonization depth data by using an image digitization tool in the embodiment;
FIG. 2 is a comparison of the average carbonation depth and the maximum carbonation depth of recycled concrete in the examples.
Detailed Description
The technical scheme of the invention is further explained by combining the attached drawings.
The method for determining the carbonization depth of the recycled concrete is characterized in that the carbonization depth values of new mortar and old mortar in the recycled concrete are all identified through an image digitization tool, and then a larger value is selected as the carbonization depth of the recycled concrete. The method can accurately predict the service life of the carbonized reinforced concrete structure containing the recycled concrete, thereby improving the safety of the structure.
Specifically, the method comprises the following steps:
step 1, coating an indicator on a fracture surface of a broken carbonized recycled concrete test piece, and distinguishing a carbonized area from a non-carbonized area;
the shape breaking method of the carbonized recycled concrete test piece can be cutting or splitting, for example, the shape breaking is started from one end of the test piece by adopting a dry sawing method, a splitting method on a pressure tester or other methods. The indicator is phenolphthalein alcohol solution, and 1% phenolphthalein alcohol solution (containing 20% distilled water) can be selected. After the indicator is coated, the time is required to be 10-20 min, the indicator is enabled to be colored, alcohol is volatilized, after the indicator is colored, a color changing area on a fracture surface of the test piece is a carbonization area, and an uncolored area is a non-carbonization area, so that the carbonization area and the non-carbonization area can be distinguished.
when the photo is taken, the shooting lens is ensured to be parallel to the fracture surface of the test piece, so that the length-width ratio of the fracture surface of the photo is ensured to be consistent with the length-width ratio of the actual fracture surface, and the test precision is improved.
And 3, converting the shot picture into a vector diagram through an image digitization tool, performing digital representation on points on a boundary line of a carbonization area and a non-carbonization area in the vector diagram, obtaining the carbonization depth value of each point, and taking the maximum value as the carbonization depth of the recycled concrete.
The image digitizing tool may employ GetData Graph Digitizer software.
The method for converting the shot photo into the vector diagram by adopting the image digitization tool comprises the following steps: and opening the shot photos by adopting an image digitization tool, establishing coordinate axes along the edges of the fracture surfaces of the recycled concrete test piece by taking the carbonization direction as an X axis and the direction orthogonal to the carbonization direction as a Y axis in the image digitization tool, respectively representing the length and the width in the photos by using the actual length and the width of the fracture surfaces, and converting the shot photos into vector diagrams.
Then, determining coordinate values of each point on a boundary line of the carbonization area and the non-carbonization area in the vector diagram in a coordinate axis, and realizing digital representation of each point; and during characterization, selecting data as much as possible to ensure the accuracy of the test result. And the abscissa value of each point on the boundary line of the carbonization area and the non-carbonization area in the coordinate axis is the carbonization depth value of each point.
Examples
A method for determining the carbonization depth of recycled concrete comprises the following steps:
step 1, a cutting method is adopted to crush carbonized recycled concrete, the section size of the concrete is 70mm multiplied by 70mm, then phenolphthalein alcohol solution with the concentration of 1% is sprayed on the cutting surface, and after 20 minutes, phenolphthalein is developed and alcohol is volatilized;
and 3, determining coordinate values of all points (namely white dots in the figure 1) on the boundary line of the discoloring area and the non-discoloring area in a coordinate axis, wherein the abscissa value of each point is the carbonization depth value of each point, as shown in the following table 1.
TABLE 1 carbonization depth values of recycled concrete
When the carbonization depth of the recycled concrete in the case is tested by adopting a method for testing the carbonization depth of the common concrete in GB/T50082-2009 test method Standard for the Long-term Performance and durability of the common concrete, namely, a maximum value and a minimum value of the data in the table 1 are removed, the rest data are averaged, and the obtained carbonization depth value d is obtained2Calculated relative standard error is 40% and average relative error is 34% at 10.06 mm. As can be seen, the result error of representing the carbonization depth of the recycled concrete by adopting the test method of the carbonization depth of the common concrete is very large. In addition, the result of testing the carbonization depth value of the recycled concrete by adopting the ordinary concrete carbonization depth testing method is 71% smaller than that of the carbonization depth testing method provided by the invention, as shown in fig. 2, if the ordinary concrete carbonization depth testing method is adopted to test the carbonization depth of the recycled concrete, the carbonization depth is small, the service life of carbonization is calculated to be large, and the safety of a concrete structure is reduced.
Claims (7)
1. A method for determining the carbonization depth of recycled concrete is characterized by comprising the following steps:
step 1, coating an indicator on a fracture surface of a broken carbonized recycled concrete test piece, and distinguishing a carbonized area from a non-carbonized area;
step 2, photographing the fracture surface of the test piece with the carbonization zone and the non-carbonization zone distinguished;
and 3, converting the shot picture into a vector diagram through an image digitization tool, performing digital representation on points on a boundary line of a carbonization area and a non-carbonization area in the vector diagram, obtaining the carbonization depth value of each point, and taking the maximum value as the carbonization depth of the recycled concrete.
2. The method for determining the carbonization depth of the recycled concrete as claimed in claim 1, wherein in step 1, the method for breaking the carbonized recycled concrete specimen is cutting or splitting.
3. The method for determining the carbonization depth of recycled concrete according to claim 1, wherein the indicator is phenolphthalein alcohol solution in step 1.
4. The method for determining the carbonization depth of the recycled concrete according to claim 1, wherein in the step 1, after the indicator is coated, the indicator is allowed to develop color after waiting for 10-20 min, wherein the color-changed area on the fracture surface of the test piece is a carbonized area, and the non-color-changed area is a non-carbonized area.
5. The method for determining the carbonization depth of recycled concrete according to claim 1, wherein in the step 2, when the fracture surface of the test piece is photographed, the photographing lens is parallel to the fracture surface of the test piece.
6. The method for determining the carbonization depth of recycled concrete according to claim 1, wherein in step 3, the image digitizing tool is GetData Graph Digitizer software.
7. The method for determining the carbonization depth of recycled concrete as claimed in claim 1, wherein in step 3, the shot picture is opened by the image digitization tool, a coordinate axis is established along the edge of the fracture surface of the recycled concrete specimen by taking the carbonization direction as an X axis and the direction orthogonal to the carbonization direction as a Y axis in the image digitization tool, the shot picture is converted into a vector diagram, and the abscissa value of each point on the boundary line of the carbonization area and the non-carbonization area in the vector diagram in the coordinate axis is determined, namely the carbonization depth value of each point.
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