A method to enhance the durability of the debonding layer in concrete expansion joints

Abstract

The application discloses a method for enhancing the durability of a debonding layer of a concrete expansion joint, and belongs to the technical field of concrete expansion joint treatment, and comprises the following steps: S1, basic preparation: cleaning the concrete surfaces on both sides of the expansion joint, ensuring that the surfaces are flat, clean and dry, and designing the structural size and shape of the debonding layer according to the size and shape of the expansion joint; the application adopts ultra-high performance concrete (UHPC) as a bottom layer material, and the strength grade of the UHPC is greater than C120; compared with the common concrete or low-performance concrete commonly used in the prior art, the UHPC has higher strength and durability, and can better withstand external loads and environmental influences. Meanwhile, a plurality of circular protrusions are arrayed and distributed on the PTFE friction layer, the protrusions are integrally formed with the PTFE friction layer, the friction between the PTFE layer and the UHPC bottom layer is enhanced, and the overall performance of the bonding layer is improved.

Description

Technical Field

[0001] This invention relates to the field of concrete expansion joint treatment technology, specifically a method for enhancing the durability of the debonding layer in concrete expansion joints. Background Technology

[0002] Concrete expansion joints are structural joints designed to accommodate temperature changes, shrinkage, and expansion in concrete structures. Their primary function is to prevent concrete cracking caused by these factors, thus ensuring the integrity and durability of the structure. A debonding layer, on the other hand, is a special material layer placed at the expansion joint to reduce friction between the concrete on either side of the joint and prevent mutual compression and shearing caused by temperature changes, shrinkage, and expansion, which could lead to joint failure.

[0003] When treating concrete expansion joints, ordinary concrete is often used for grouting. This material has low strength and poor durability, making it prone to cracking and wear under long-term loads and environmental factors, leading to a decline in the performance of the debonding layer. Furthermore, insufficient crack control measures for the concrete expansion joint debonding layer easily result in cracks, further affecting the overall performance and durability of the structure. Therefore, a method to enhance the durability of the concrete expansion joint debonding layer is proposed.

[0004] The information disclosed above in this background section is only for enhancing the understanding of the background section of this invention, and therefore may include prior art that is not known to those skilled in the art. Summary of the Invention

[0005] The present invention aims to at least solve one of the technical problems existing in the prior art. Therefore, one object of the present invention is to provide a method for enhancing the durability of the debonding layer in concrete expansion joints.

[0006] To achieve the above objectives, the present invention provides the following technical solution:

[0007] A method for enhancing the durability of the debonding layer in concrete expansion joints includes the following steps:

[0008] S1. Basic preparation: Clean the concrete surface on both sides of the expansion joint to ensure that the surface is flat, clean and dry. Design the structural dimensions and shape of the release layer according to the size and shape of the expansion joint.

[0009] S2. Construction of UHPC base layer: Mix the UHPC mixture evenly and pour it into the PTFE layer. Use a vibrator to compact the mixture to ensure that the UHPC layer is dense and flat. Roughen the surface of the UHPC base layer to improve the bonding strength with the PTFE layer.

[0010] S3. PTFE Friction Layer Construction: Bond the PTFE material to the UHPC base layer using a high-performance adhesive. Use a pressure roller to press the PTFE onto the UHPC material and ensure that the PTFE adheres to the expansion joint. Use a vibrator to perform light compaction to ensure that the PTFE layer is firmly bonded to the UHPC base layer.

[0011] S4. Construction of UHPC Top Layer: Mix the UHPC mixture evenly and pour it into the container. Use a vibrator to compact the mixture to ensure that the UHPC top layer is dense and flat. Use a grinder to polish the UHPC top layer to make its surface smooth and flat.

[0012] S5. Curing and Acceptance: Curing the debonded layer to ensure that the strength of the UHPC material meets the design requirements, and accepting the debonded layer to check whether its size, shape, flatness, and bonding strength meet the design requirements.

[0013] As a further optimization of the present invention, in step 1, UHPC selects a concrete material with a strength greater than C120.

[0014] As a further optimization of the present invention, in step 3, the high-performance adhesive is a modified epoxy resin adhesive.

[0015] As a further optimization of the present invention, in step 3, multiple circular protrusions are arrayed on the PTFE friction layer, and the PTFE friction layer and the circular protrusions are integrally formed.

[0016] As a further optimization of the present invention, in step 4, the initial polishing is performed 15-30 minutes after pouring, and the secondary polishing is performed 1-2 hours after the initial polishing.

[0017] Compared with the prior art, the beneficial effects of the present invention are:

[0018] This invention uses ultra-high performance concrete (UHPC) as the base layer material, with a strength grade greater than C120. Compared to ordinary concrete or low-performance concrete commonly used in existing technologies, UHPC has higher strength and durability, and can better withstand external loads and environmental impacts. Simultaneously, multiple circular protrusions are arrayed on the PTFE friction layer. These protrusions are integrally formed with the PTFE friction layer, enhancing the friction between the PTFE layer and the UHPC base layer, and improving the overall performance of the bonding layer.

[0019] This invention uses a modified epoxy resin adhesive, which has better bonding strength, tensile strength, compressive strength and chemical resistance. Compared with traditional adhesives, the modified epoxy resin adhesive can provide a more reliable bonding effect. Through innovation in the method and process, the durability of the debonding layer of concrete expansion joints is improved, the risk of cracking and debonding is reduced, and the service life of expansion joints is extended.

[0020] The above overview is for illustrative purposes only and is not intended to be limiting in any way. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features of the invention will become readily apparent from the accompanying drawings and the following detailed description. Attached Figure Description

[0021] Figure 1 This is a flowchart of the method for enhancing the durability of the debonding layer in concrete expansion joints according to the present invention;

[0022] Figure 2 This is a schematic diagram of the internal structure of the UHPC top layer and PTFE friction layer of the present invention.

[0023] In the diagram: 10, UHPC top layer; 20, PTFE friction layer; 30, circular protrusion; 40, UHPC bottom layer. Detailed Implementation

[0024] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] like Figure 1 As shown, a method for enhancing the durability of the debonding layer in concrete expansion joints includes the following steps:

[0026] S1. Basic preparation: Clean the concrete surface on both sides of the expansion joint to ensure that the surface is flat, clean and dry. According to the size and shape of the expansion joint, design the structural size and shape of the debonding layer. UHPC should be made of concrete material with a grade greater than C120.

[0027] Specifically, use a high-pressure water gun or wire brush to initially clean the concrete surface on both sides of the expansion joint, removing dust, dirt, oil, and other adhering substances. Use a grinder to grind the concrete surface on both sides of the expansion joint, removing laitance and dirt to make the surface smoother. Depending on the actual conditions of the construction site, acid or alkaline washing methods can be used to chemically clean the concrete surface on both sides of the expansion joint, removing the carbonized layer, dirt, oil, paint, etc. Finally, use a vacuum cleaner to perform a final cleaning of the concrete surface on both sides of the expansion joint, ensuring the surface is clean, dry, and smooth.

[0028] S2. Construction of UHPC base layer 40: Mix the UHPC mixture evenly and pour it. Use a vibrator to compact it to ensure that the UHPC base layer 40 is dense and flat. Roughen the surface of the UHPC base layer to improve the bonding strength with the PTFE layer.

[0029] Specifically, the mixing steps for UHPC are as follows: First, add dry materials such as cement, mineral admixtures, sand, and stone to the mixer for initial mixing to ensure uniformity. Then, slowly add an appropriate amount of water to the mixer and mix with the dry materials until the mixture reaches the required fluidity and viscosity. Next, add additives such as admixtures and fibers to the mixer and mix thoroughly to ensure uniform dispersion. The mixing time is 5-10 minutes.

[0030] The mixed UHPC (Ultra-High-Pressure Polymer) compound is transported to the construction site and poured evenly onto the bottom layer of the expansion joint. A vibrator is used to compact the poured UHPC compound, removing air bubbles and ensuring density. The vibrator should be moved evenly during vibration to avoid over-vibration or under-vibration, ensuring the entire UHPC layer is uniformly dense. Vibration continues until slurry appears on the surface of the compound, with no significant settling or air bubbles. After vibration, a plate vibrator or hand tools are used to initially level the surface of the UHPC layer, ensuring the surface flatness meets requirements.

[0031] Before the UHPC layer initially sets, roughen the surface using a roughening tool to increase its surface roughness and improve the bond strength with the subsequent PTFE layer. The roughening should be uniform, avoiding over- or under-roughening to prevent affecting the bonding effect. After the UHPC base layer is constructed, check its density, flatness, and roughening effect; repair any defects promptly.

[0032] S3. PTFE Friction Layer Construction: Bond the PTFE material to the UHPC base layer using a high-performance adhesive. Use a pressure roller to press the PTFE onto the UHPC material and ensure that the PTFE adheres to the expansion joint. Use a vibrator to perform light compaction to ensure that the PTFE layer is firmly bonded to the UHPC base layer.

[0033] Among them, the high-performance adhesive is a modified epoxy resin adhesive.

[0034] Modified epoxy resin adhesives possess extremely high bonding strength, effectively bonding PTFE and UHPC materials. They maintain their performance within a temperature range of -40℃ to 150℃. They exhibit good resistance to corrosion from acids, alkalis, and salts. They also demonstrate excellent anti-aging properties, maintaining their bonding effect for extended periods even in harsh environments. The mixing ratio is simple, operation is convenient, and the curing time is adjustable.

[0035] Specifically, the first step is surface preparation. Inspect the surface of the UHPC bottom layer to ensure it is free of dust, oil, and moisture. You can use appropriate sandpaper or a grinder to lightly sand the UHPC bottom layer to increase surface roughness and improve adhesion.

[0036] Accurately weigh the epoxy resin, curing agent, toughening agent, filler, and accelerator, and use an electric mixer to mix the components thoroughly until the adhesive reaches a uniform viscous consistency.

[0037] Use a scraper to evenly apply the mixed adhesive to the UHPC base layer, ensuring a consistent coating thickness. The adhesive should be applied beyond the PTFE material coverage area to ensure proper adhesion at the edges.

[0038] Lay the PTFE material flat on the UHPC base layer that has been coated with adhesive, ensuring the material is free of wrinkles and air bubbles. Gently press the PTFE material with a roller to ensure it adheres tightly to the UHPC base layer.

[0039] Use a vibratory rod to gently compact the PTFE material, removing air bubbles and ensuring adhesion between the PTFE layer and the UHPC base layer. Continue to compact the PTFE material using a pressure roller to ensure even distribution of the adhesive and complete bonding of the PTFE material. Allow the adhesive to cure at room temperature, or use heating to accelerate the curing process. After curing, inspect the adhesion of the PTFE layer to ensure there are no air pockets or delamination. If air pockets or delamination are found, repair the areas where the adhesion is weak. After the PTFE layer has cured, cover it with plastic film or use temporary supports to prevent damage during subsequent construction or use.

[0040] like Figure 2 As shown, multiple circular protrusions 30 are arrayed on the PTFE friction layer, and the PTFE friction layer 20 and the circular protrusions 30 are integrally formed.

[0041] Polytetrafluoroethylene (PTFE) material has a low coefficient of friction, and multiple circular protrusions 30 extend and penetrate into the interior of the UHPC bottom layer. Its contact area is smaller than that of traditional release layers, which can reduce friction.

[0042] S4. Construction of UHPC Top Layer 10: Mix the UHPC mixture evenly and pour it into the container. Use a vibrator to compact the mixture to ensure that the UHPC top layer is dense and flat. Use a grinder to polish the UHPC top layer 10 to make its surface smooth and flat.

[0043] Specifically, the initial polishing begins when the top layer of the UHPC has initially set. Start the polisher and move it slowly across the UHPC surface, working from the edges towards the center to avoid material buildup. The polisher should be angled approximately 30° to the ground.

[0044] After the initial polishing, check the surface for any unevenness or local depressions. Use a plate vibrator to vibrate the uneven areas to promote the redistribution and settling of the material.

[0045] After the UHPC surface has further solidified, a second polishing is performed. The polisher should move at a more uniform speed to ensure a smoother and flatter surface. Adjust the speed and angle of the polisher to suit different UHPC surface conditions. For edges and corners that are difficult to reach with the polisher, use a hand grinder to ensure consistency with the substrate surface.

[0046] After polishing, carefully inspect the entire UHPC top layer to ensure there are no missed areas, scratches, or tool marks. If any defects are found, they should be repaired and re-polished immediately.

[0047] After polishing, take timely curing measures according to the UHPC material and site conditions, such as covering with plastic film, damp cloth, or applying curing agents, to prevent premature drying and cracking. Avoid heavy machinery and personnel walking on the UHPC top layer until it is fully hardened to prevent damage.

[0048] The initial polishing is carried out 15-30 minutes after pouring, and the second polishing is carried out 1-2 hours after the initial polishing.

[0049] S5. Curing and Acceptance: Curing the debonded layer to ensure that the strength of the UHPC material meets the design requirements, and accepting the debonded layer to check whether its size, shape, flatness, and bonding strength meet the design requirements.

[0050] Specifically, after the top layer of the UHPC is polished, the curing process begins. The UHPC surface is covered with plastic film, a damp cloth, or a water sprayer to keep it moist and prevent moisture evaporation. This moisture level should be maintained for at least 24 hours. After the initial curing, continue curing for 7-14 days to ensure the UHPC material is fully hydrated. Regularly check the covering to ensure it is intact and that the UHPC surface remains consistently moist. Avoid exposing the UHPC to direct sunlight, high temperatures, or freezing temperatures during the curing period.

[0051] After the curing period, gradually reduce the surface moisture and allow the UHPC to dry naturally. Once it is confirmed that the UHPC material has reached its design strength, remove all curing coverings.

[0052] After the curing period, prepare for the acceptance of the debonded layer. Confirm the acceptance standards and procedures, and prepare the necessary testing tools and equipment, such as rulers, levels, and pull-out testers. Use measuring tools to check the size and shape of the debonded layer and record all measurement data.

[0053] Use a ruler and level to check the flatness of the release layer. Confirm that the surface is free of obvious unevenness or waviness. Use a pull-out tester to test the bond strength of the release layer. Based on the test results, assess whether the bond strength meets the design requirements. Visually inspect the appearance of the release layer to ensure there are no defects such as cracks, honeycombing, or pitting. Check the uniformity of color and texture. Based on the inspection and test results, prepare an acceptance report. If any non-compliance with design requirements is found, record it and develop corresponding corrective measures. Rectify the problems found during acceptance. After rectification, conduct a re-acceptance to ensure all problems have been resolved.

[0054] Experimental Comparative Example

[0055] Experimental objective: To verify the durability of the debonding layer in reinforced concrete expansion joints. One group used the method of this invention (experimental group), and the other group used the traditional construction method (control group).

[0056] Experimental materials and equipment: concrete expansion joint model, UHPC material (ultra-high performance concrete), PTFE material (polytetrafluoroethylene), traditional epoxy resin adhesive (control group), modified epoxy resin adhesive (experimental group), pull-out tester, temperature and humidity recorder, crack observation instrument;

[0057] Experimental steps:

[0058] Step 1: Create concrete expansion joint models, ensuring that each model has the same size and structure.

[0059] Step 2: The experimental group was constructed according to the method of this invention, while the control group was constructed according to the traditional method.

[0060] Step 3: Apply the same curing conditions to both sets of models and record the temperature and humidity data.

[0061] Step 4: After a certain curing period, use a pull-out tester to test the bond strength of the debonded layer.

[0062] Step 5: Use a crack observation instrument to record the crack development of the debonded layer under simulated conditions.

[0063] Experimental Table:

[0064]

[0065] Analysis of experimental results:

[0066] The bond strength of the experimental group was significantly higher than that of the control group, indicating that the method of this invention can provide stronger bonding performance. The width and number of cracks in the experimental group were both smaller than those in the control group, demonstrating that the method of this invention can effectively reduce crack formation and improve the overall performance of the debonded layer. The high bond strength and fewer cracks in the experimental group prove that this method has better durability in long-term use.

[0067] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0068] The accompanying drawings of the embodiments disclosed in this invention only involve structures relevant to the embodiments of this disclosure. Other structures can be referred to with common design. Unless otherwise specified, the same embodiment and different embodiments of this invention can be combined with each other. In addition, for the purpose of providing a concise description of exemplary embodiments, not all features of the actual embodiments (i.e., those features that are not related to the currently considered best mode for carrying out the invention, or those features that are not related to implementing the invention) may be omitted.

[0069] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method of enhancing the durability of a concrete expansion joint debonding layer, characterized by, The method comprises the following steps: S1. Basic preparation: clean the concrete surface on both sides of the expansion joint, ensure the surface is flat, clean and dry, and design the structural size and shape of the debonding layer according to the size and shape of the expansion joint; S2. UHPC bottom layer construction: uniformly stir the UHPC mixture and pour it, use a vibrating rod to vibrate it, ensure that the UHPC layer is dense and flat, and perform a scratching treatment on the surface of the UHPC bottom layer to improve the bonding strength with the PTFE layer; S3. PTFE friction layer construction: use a high-performance adhesive to bond the PTFE material on the UHPC bottom layer, use a press roller to press the PTFE onto the UHPC material, and make the PTFE adhere to the expansion joint; use a vibrating rod to slightly vibrate it to ensure that the PTFE layer is firmly bonded to the UHPC bottom layer; The high-performance adhesive is a modified epoxy resin adhesive; The PTFE friction layer is provided with a plurality of circular protrusions arranged in an array, and the PTFE friction layer and the circular protrusions are integrally formed, and the plurality of circular protrusions extend through the UHPC bottom layer; S4. UHPC top layer construction: uniformly stir the UHPC mixture and pour it, use a vibrating rod to vibrate it, ensure that the UHPC top layer is dense and flat, and use a sander to polish the UHPC top layer to make its surface smooth and flat; S5. Maintenance and acceptance: maintain the debonding layer to ensure that the UHPC material strength meets the design requirements, and check whether the size, shape, flatness and bonding strength of the debonding layer meet the design requirements.

2. A method of enhancing the durability of a debonding layer of a concrete expansion joint according to claim 1, characterized in that: In step 1, the UHPC is selected to be a concrete material with a strength greater than C120.

3. A method of enhancing the durability of a debonding layer of a concrete expansion joint according to claim 1, wherein: In step 4, the initial polishing is performed 15-30 minutes after pouring, and the secondary polishing is performed 1-2 hours after the initial polishing.

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