High-pressure water jet cleaning method suitable for removing mortar attached to large-size recycled aggregate

Abstract

The application discloses a high-pressure water jet cleaning method suitable for removing attached mortar of large-diameter recycled aggregate, and mainly relates to the technical field of hydraulic engineering construction. The application tests the surface mortar adhesion of the large-diameter recycled aggregate (recycled block stone) removed from an original dam, removes the attached mortar by using a high-pressure water jet technology, and determines the relationship between the mortar adhesion and the working pressure and flow of the high-pressure water jet. The attached mortar of the large-diameter recycled aggregate (recycled block stone) of the original dam is cleaned in batches by selecting appropriate working conditions of the high-pressure water jet, and the image recognition technology is combined to ensure that the cleaning rate of the attached mortar is greater than or equal to 98%. The method is efficient, safe and environmentally friendly, avoids chemical cleaning from causing chemical erosion and secondary pollution to the recycled aggregate, the working pressure and flow of the high-pressure water jet can be adjusted, the recycled aggregate substrate is not damaged, and the quality of the cleaned recycled aggregate is equivalent to that of natural aggregate.

Description

Technical Field

[0001] This invention relates to a method for surface modification treatment of large-diameter recycled aggregates, and more particularly to the removal treatment of mortar adhering to the surface of large-diameter recycled aggregates, belonging to the field of water conservancy engineering construction. Background Technology

[0002] As time goes by, the reservoirs and hydropower dams built in the 1970s are gradually reaching the end of their service life. Problems are emerging, such as increased porosity in the concrete panels, localized cracks and damage to the masonry structure, deterioration of the bonding in the anti-seepage walls, an increase in leakage points, and a year-on-year increase in seepage, seriously affecting the safe operation of the dams. To completely eliminate safety hazards and prevent the reservoirs from operating with these defects for a long time and threatening downstream residents, it is necessary to demolish and rebuild the dams. Dams built in the 1970s were generally masonry dams. The demolition of the original dams will generate a large amount of rubble. If these rubble are disposed of as solid waste through landfill, it will occupy a large amount of land resources and damage the soil ecosystem. At the same time, using newly mined rubble in the construction of new dams will lead to increased costs and over-exploitation of natural resources. Therefore, adapting to local conditions and using locally sourced materials, reusing the rubble from the demolished dams can reduce procurement costs, save energy consumption, conserve land, and protect the environment.

[0003] Because the removed riprap has mortar adhering to its surface, it severely affects the water absorption rate of the riprap and the bonding strength between the old and new concrete layers, failing to meet the requirements for riprap recycling. Therefore, it is necessary to perform surface modification treatment on the original dam riprap to remove the adhering mortar and form large-particle-size recycled aggregate (recycled riprap, particle size ≥ 200mm) that meets the usage requirements. Currently, surface modification treatment methods for recycled aggregate generally include chemical solution soaking, cleaning and drying with detergents, ultrasonic cleaning, and mechanical friction cleaning. These methods have problems such as complex processes, high cleaning costs, and environmental pollution from chemical agents.

[0004] To better utilize the original dam demolition riprap, it is necessary to thoroughly remove the mortar adhering to the surface of the riprap to ensure it meets the required usage specifications. Therefore, this invention proposes a high-pressure water jet cleaning method suitable for removing mortar adhering to large-diameter recycled aggregates, to solve the aforementioned problem. Summary of the Invention

[0005] To address the problems existing in the prior art, the present invention aims to provide a method for efficiently removing mortar adhering to large-diameter recycled aggregate. This method is reliable in principle, safe and environmentally friendly, has a high cleaning rate, and does not damage the cleaned material. The large-diameter recycled aggregate (recycled boulders) cleaned is of good quality, comparable to that of natural boulders.

[0006] To achieve the above objectives, the technical solution of the present invention is as follows:

[0007] A high-pressure water jet cleaning method for removing mortar adhering to large-diameter recycled aggregates is provided, the method comprising testing the adhesion strength of the mortar and removing the mortar with high-pressure water jet.

[0008] The nominal particle size of the large-particle-size recycled aggregate (recycled boulders) is ≥200mm.

[0009] The adhesion strength test of the mortar was conducted using the tensile bond strength test method in the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T70–2009. Specifically, a high-strength adhesive such as epoxy resin was applied to the surface of the mortar. A tensile clamp was then placed precisely on the adhesive, ensuring it was not tilted. After the epoxy resin had solidified for 24 hours, a tensile bond strength test was performed using a tensile testing machine to determine the adhesion strength of the mortar. This tensile bond strength test determines the adhesion strength of the mortar and cement paste to large-diameter recycled aggregate (recycled boulders), providing a basis for selecting the appropriate high-pressure water jet working pressure and flow rate.

[0010] The high-pressure water jet removal of adhering mortar involves using a high-pressure water jet device to wash away the mortar adhering to the surface of large-diameter recycled aggregate (recycled boulders). The working pressure of the high-pressure water jet is adjustable in the range of 50 to 1000 bar, the water flow rate is adjustable in the range of 5 to 30 L / min, and the water outlet angle is adjustable in the range of 0 to 40°.

[0011] Furthermore, after the large-diameter recycled aggregate (recycled rubble) is washed with high-pressure water jet, the removal rate of the attached mortar is assessed using image recognition technology to ensure that the removal rate of the attached mortar is ≥98%. If some mortar remains on the surface of the large-diameter recycled aggregate (recycled rubble), the working pressure and flow rate of the high-pressure water jet are further increased until more than 98% of the attached mortar is removed.

[0012] Furthermore, the image recognition technology mainly involves binarizing the image of the attached mortar. The mortar exhibits pixel densities before and after cleaning. The pixel density of the cleaned mortar image is compared with the total pixel density of the mortar image before cleaning. If the ratio of the pixel density of the cleaned mortar image to the total pixel density of the mortar image before cleaning is ≤2%, the mortar removal rate is determined to be ≥98%.

[0013] Furthermore, the working pressure and flow rate of the high-pressure water jet were adjusted sequentially from low to high to continuously clean the mortar adhering to the large-diameter recycled aggregate (recycled boulders). When the mortar cleaning rate was ≥98%, the working pressure and flow rate of the high-pressure water jet corresponded to the bonding force of the mortar. The relationship between the bonding force of the mortar and the working pressure and flow rate of the high-pressure water jet was determined in this way, as shown in Table 1, which facilitates the selection and determination of subsequent high-pressure water jet working conditions.

[0014] Table 1. Relationship between Adhesion Mortar Bonding Strength and High-Pressure Water Jet Working Conditions

[0015]

[0016]

[0017] Furthermore, when dismantling reservoir dams and hydropower station dams, the dismantling is generally carried out layer by layer and section by section from top to bottom. Meanwhile, affected by the dry season and the rainy season, the dam water level fluctuates year-round, resulting in inconsistent weathering and bonding strength degradation of the masonry mortar in the upper, middle, and bottom parts of the dam. To improve work efficiency, large-diameter recycled aggregate (recycled rubble) is used in batches every 10 meters from top to bottom according to the dam height. The bonding strength of the dam masonry mortar in each batch of large-diameter recycled aggregate (recycled rubble) is tested 5-10 times. Based on the maximum bonding strength and the relationship between the bonding strength of the aforementioned attached mortar and the working pressure and flow rate of the high-pressure water jet, the appropriate high-pressure water jet working pressure and flow rate are selected for mortar removal.

[0018] Furthermore, removing the adhering mortar in batches can reduce the frequency of testing the adhesion of the adhering mortar, thereby improving work efficiency. At the same time, by combining image recognition technology, it can be ensured that the adhering mortar removal rate of each batch of large-diameter recycled aggregate (recycled blocks) is above 98%; if some mortar remains on the surface of the large-diameter recycled aggregate (recycled blocks), the working pressure and flow rate of the high-pressure water jet are further increased.

[0019] High-pressure water jet cleaning of mortar adhering to the surface of large-diameter recycled aggregate (recycled boulders) is carried out above a three-stage settling tank. The three-stage settling tank is equipped with a steel mesh, and the waste mortar particles washed out can fall into the settling tank through the screen holes of the steel mesh and be collected and reused. At the same time, the cleaning water can also be recycled, achieving the purpose of saving water and protecting the ecological environment.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0021] (1) Large-diameter recycled aggregate (recycled rubble) has high cleaning efficiency with attached mortar, and the removal rate of attached mortar is greater than 98%.

[0022] (2) No chemical solution soaking is required, which avoids chemical erosion of the recycled aggregate; at the same time, no excess chemical reagents on the surface of the recycled aggregate need to be rinsed off, which avoids secondary pollution.

[0023] (3) The working pressure and flow rate of the high-pressure water jet can be adjusted without damaging the recycled aggregate matrix; the high-pressure water jet cleaning is a physical cleaning method, and the apparent physical and chemical properties of the recycled aggregate are not affected; the quality of the recycled aggregate after cleaning is good and comparable to that of natural aggregate.

[0024] (4) High-pressure water jet cleaning of large-diameter recycled aggregate (recycled rubble) with attached mortar is low-cost, about 1 / 3 of that of chemical cleaning. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of a high-pressure water jet cleaning method suitable for removing mortar adhering to large-diameter recycled aggregate;

[0026] Figure 2 A flowchart illustrating the process of testing the adhesion strength of mortar to large-diameter recycled aggregate.

[0027] Figure 3 This is a rendering of the large-diameter recycled aggregate before cleaning (during dismantling).

[0028] Figure 4 This is a picture showing the effect of washing large-particle-size recycled aggregate. Detailed Implementation

[0029] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments:

[0030] like Figure 1-4 As shown,

[0031] Example 1

[0032] According to the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T70–2009, the bonding strength of mortar with large-diameter recycled aggregate (recycled rubble) was tested using a Haichuang Gaoke HC-D10 electric bonding strength tester, and the test result was 0.13 MPa. Based on the relationship between the bonding strength of the mortar and the working conditions of the high-pressure water jet, the working pressure and flow rate of the high-pressure water jet were set to 70 bar and 8 L / min, respectively, and the water outlet angle of the high-pressure water jet was set to 20°.

[0033] Large-diameter recycled aggregate (recycled boulders) was placed above a three-stage settling tank. The working pressure, flow rate, and outlet angle of the high-pressure water jet were adjusted to 70 bar, 8 L / min, and 20°, respectively, to clean the mortar adhering to the surface of the large-diameter recycled aggregate (recycled boulders). After cleaning, image recognition technology was used to detect the residual mortar on the surface of the recycled aggregate. More than 98% of the adhering mortar was removed, meeting the requirements for standard use.

[0034] The tertiary sedimentation tank is used to collect the waste mortar particles washed off, preventing secondary pollution of the environment. At the same time, the water recycled through the tertiary sedimentation tank saves water resources.

[0035] Example 2

[0036] According to the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T70–2009, the bonding strength of mortar with large-diameter recycled aggregate (recycled rubble) was tested using the Haichuang Gaoke HC-D10 electric bond strength tester, and the test result was 0.45 MPa. Based on the relationship between the bonding strength of the mortar and the working conditions of the high-pressure water jet, the working pressure and flow rate of the high-pressure water jet were set to 100 bar and 10 L / min, respectively, and the water outlet angle of the high-pressure water jet was set to 40°.

[0037] Large-diameter recycled aggregate (recycled boulders) was placed above a three-stage settling tank. The working pressure, flow rate, and outlet angle of the high-pressure water jet were adjusted to 100 bar, 10 L / min, and 40°, respectively, to clean the mortar adhering to the surface of the large-diameter recycled aggregate (recycled boulders). After cleaning, image recognition technology was used to detect the residual mortar on the surface of the recycled aggregate. More than 98% of the adhering mortar was removed, meeting the requirements for standard use.

[0038] The tertiary sedimentation tank is used to collect the waste mortar particles washed off, preventing secondary pollution of the environment. At the same time, the water recycled through the tertiary sedimentation tank saves water resources.

[0039] Example 3

[0040] According to the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T70–2009, the bonding strength of mortar with large-diameter recycled aggregate (recycled rubble) was tested using the Haichuang Gaoke HC-D10 electric bonding strength tester, and the test result was 1.29 MPa. Based on the relationship between the bonding strength of the mortar and the working conditions of the high-pressure water jet, the working pressure and flow rate of the high-pressure water jet were set to 200 bar and 17 L / min, respectively, and the water outlet angle of the high-pressure water jet was set to 30°.

[0041] Large-diameter recycled aggregate (recycled boulders) was placed above a three-stage settling tank. The working pressure, flow rate, and outlet angle of the high-pressure water jet were adjusted to 200 bar, 17 L / min, and 30°, respectively, to clean the mortar adhering to the surface of the large-diameter recycled aggregate (recycled boulders). After cleaning, image recognition technology was used to detect the residual mortar on the surface of the recycled aggregate. More than 98% of the adhering mortar was removed, meeting the requirements for standard use.

[0042] The tertiary sedimentation tank is used to collect the waste mortar particles washed off, preventing secondary pollution of the environment. At the same time, the water recycled through the tertiary sedimentation tank saves water resources.

[0043] Example 4

[0044] According to the "Standard for Test Methods of Basic Performance of Building Mortar" JGJ / T70–2009, the bonding strength of mortar with large-diameter recycled aggregate (recycled rubble) was tested using the Haichuang Gaoke HC-D10 electric bonding strength tester, and the test result was 1.94 MPa. Based on the relationship between the bonding strength of the mortar and the working conditions of the high-pressure water jet, the working pressure and flow rate of the high-pressure water jet were set to 300 bar and 20 L / min, respectively, and the water outlet angle of the high-pressure water jet was 0°.

[0045] Large-diameter recycled aggregate (recycled boulders) was placed above a three-stage settling tank. The working pressure, flow rate, and outlet angle of the high-pressure water jet were adjusted to 300 bar, 20 L / min, and 0°, respectively, to clean the mortar adhering to the surface of the large-diameter recycled aggregate (recycled boulders). After cleaning, image recognition technology was used to detect the residual mortar on the surface of the recycled aggregate. More than 98% of the adhering mortar was removed, meeting the requirements for standard use.

[0046] The tertiary sedimentation tank is used to collect the waste mortar particles washed off, preventing secondary pollution of the environment. At the same time, the water recycled through the tertiary sedimentation tank saves water resources.

[0047] As shown in Table 2, by selecting the appropriate high-pressure water jet working conditions for mortar removal based on the adhesion strength of the mortar, the mortar removal rate reached over 98%, meeting the requirements of the specifications.

[0048] Table 2. High-pressure water jet cleaning effect

[0049]

[0050] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any changes or substitutions conceived without inventive effort should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope defined in the claims.

Claims

1. A high-pressure water jet cleaning method for removing mortar adhering to large-diameter recycled aggregate, wherein the large-diameter recycled aggregate has a nominal particle size ≥ 200 mm and originates from the demolition of an old dam, characterized in that... Includes the following steps: Step 1: Bond strength test. Large-diameter recycled aggregates from the demolition of old dams are divided into batches according to their height in the original dam. Samples of each batch of recycled aggregates are taken and tensile bond strength test is used to determine the bond strength of the mortar attached to their surface. Step 2: Parameter matching. Based on the measured adhesion strength of the mortar, refer to the pre-established relationship table between adhesion strength of the mortar and working conditions of high-pressure water jet, and select the corresponding working pressure and flow rate of the high-pressure water jet. Step 3: High-pressure water jet cleaning. Using the selected working pressure and flow rate, high-pressure water jet technology is used to clean all the large-diameter recycled aggregates in this batch. Step 4: Cleaning rate verification. After cleaning, image recognition technology is used to detect the residual mortar on the surface of the recycled aggregate. The percentage of mortar pixels before and after cleaning is calculated by image binarization. When the percentage is ≤2%, the mortar cleaning rate is determined to be ≥98%. The high-pressure water jet cleaning is carried out above the three-stage sedimentation tank, and the wastewater and mortar particles generated during cleaning are collected, settled, and recycled through the three-stage sedimentation tank.

2. The method according to claim 1, characterized in that, The tensile bond strength test in step one is specifically as follows: apply a high-strength adhesive to the surface of the mortar, align the tensile special fixture and place it on the adhesive, and after the adhesive has solidified, use a tensile testing machine to test the tensile bond strength.

3. The method according to claim 1, characterized in that, In step three, the working pressure of the high-pressure water jet is 50-1000 bar, the water flow rate is 5-30 L / min, and the water outlet angle is 0-40°.

4. The method according to claim 1, characterized in that, The image recognition in step four specifically involves: acquiring images before and after cleaning using a high-definition camera, performing image binarization using image recognition software, calculating the ratio M2 / M1 of the image pixels M2 of the mortar after cleaning to the total image pixels M1 of the mortar before cleaning, and determining that the cleaning rate meets the standard when M2 / M1 ≤ 2%.

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