Method for determining minimum thickness of waterproofing membrane for bridge crash barrier side water stop
By constructing a composite specimen of cement concrete panel-waterproof membrane-asphalt mixture at the edge of bridge crash barrier and using a gradient thickness increase test, the problem of water seepage at the joints at the edge of bridge crash barrier was solved, the precise design of the minimum thickness of waterproof membrane was achieved, and the durability and economy of bridge deck paving were improved.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- ZHEJIANG SCI RES INST OF TRANSPORT
- Filing Date
- 2026-06-23
- Publication Date
- 2026-07-31
AI Technical Summary
The existing technology lacks a method for determining the thickness of waterproof membrane at the joints of bridge crash barriers, which leads to water seepage from the junction of the crash barrier and the asphalt pavement, affecting the structural stability and durability of the bridge.
By constructing composite specimens of cement concrete panels, waterproof membranes, and asphalt mixtures, and employing gradient thickness increment tests, the permeability coefficient at the joints was detected, and the minimum thickness of the waterproof membrane was determined to meet the differentiated needs of different asphalt mixture types.
The minimum thickness of waterproof membrane that prevents water seepage at the edges of bridge crash barriers has been determined, improving the durability of bridge deck pavement, reducing construction costs and difficulty, and adapting to the characteristics of different asphalt mixtures.
Smart Images
Figure CN122487203A_ABST
Abstract
Description
Technical Field
[0001] This invention provides a method for determining the minimum thickness of waterproof membrane for edge sealing of bridge crash barriers, belonging to the field of road engineering technology. Background Technology
[0002] Currently, cement concrete bridges are widely used in municipal roads and highways in my country, with asphalt concrete and composite pavement being the most common types. The bridge deck of a cement concrete bridge directly bears the wheel loads generated by vehicles passing over the road surface and is also susceptible to deterioration factors such as rainwater, making it the component in the harshest environment among bridge components. Insufficient waterproofing of the bridge deck leads to water penetration, causing corrosion of the reinforcing steel, concrete, and steel components. This deterioration weakens the structural integrity and stability of the bridge, significantly increasing safety risks. Furthermore, water entering the pavement interior can cause water vapor on the bridge deck to detach from the waterproofing adhesive layer, gradually forming cracks, ruts, and other defects under traffic loads. Asphalt pavements will also develop potholes under the influence of moving water.
[0003] There are three main ways water can enter the bridge deck pavement system: first, insufficient compaction and high porosity allow rainwater to seep in from the surface; second, it seeps in through construction joints; and third, it enters at the interface between the crash barrier and the asphalt pavement. The crash barrier is rigid, while the asphalt pavement is flexible; the interface between the two inevitably has gaps due to the difference in material properties, making it one of the main channels for water seepage. To address the issue of water entering through these gaps at the interface between the crash barrier and the asphalt pavement, a waterproof membrane can be pasted at the bottom of the barrier where it meets the asphalt pavement. The high temperature during asphalt mixture compaction softens the waterproof membrane, filling the gaps and eliminating the gap between the asphalt pavement and the crash barrier. However, existing technologies have the following shortcomings: (1) Existing research mainly proposes minimum thickness recommendations (e.g., ≥2.5mm for the adhesive layer of bridge deck waterproofing) for the resistance to construction damage, but does not consider the differences in stress, deformation and functional characteristics of the waterproof membrane at the joints of the guardrail edge with the bridge deck waterproofing adhesive layer. Therefore, there is a lack of a method for determining the thickness of the waterproof membrane for the specific working condition of filling the gaps at the joints of the guardrail edge.
[0004] (2) Different asphalt mixtures or different gradations of the same asphalt mixture have significantly different permeability coefficients under the same waterproof membrane thickness. The compression and filling effects on the waterproof membrane during compaction are different. Different thickness design methods are needed for different mixture types to avoid the failure of a "one-size-fits-all" fixed thickness under some working conditions (insufficient thickness leads to water seepage) and over-design under other working conditions (excessive thickness increases costs). Fixed thickness cannot meet all working conditions.
[0005] Therefore, it is necessary to invent a method for determining the minimum thickness of waterproof membrane for water-stopping the edge of bridge crash barriers. Summary of the Invention
[0006] To overcome the shortcomings of the existing technology, this invention addresses the specific condition of water sealing at the joints of guardrail edges. It constructs a composite specimen of cement concrete panel, waterproof membrane, and asphalt mixture, uses the water permeability coefficient at the joint as the criterion, and employs a gradient thickness increase test to determine the minimum thickness of the waterproof membrane for different types of asphalt mixture.
[0007] This application provides a method for determining the minimum thickness of a waterproof membrane for edge sealing of bridge crash barriers, comprising the following steps: Step 1: Molding cement concrete panels: Molding cement concrete panels according to the cement concrete mix proportions used for the crash barrier; Step 2, Embedding the test mold: Embed the cement concrete panel into the test mold; Step 3: Prepare waterproof membrane samples: Prepare waterproof membrane samples of different thicknesses using non-woven bitumen waterproof membrane material for later use. Step 4: Adhere the waterproof membrane sample: Utilize the self-adhesiveness of the non-woven bitumen waterproof membrane to directly adhere the waterproof membrane sample with a thickness of n to the side of the cement concrete panel, where the initial value of n is 2mm. Step 5: Prepare composite specimen slabs: Mix at least one layer of asphalt mixture according to the mix proportion of the asphalt mixture used for bridge deck paving, fill it into the remaining space on the side of the cement concrete panel in the test mold, form the composite specimen using the wheel rolling method, and remove it after cooling. Step 6, Permeability Test: Align the center of the permeability meter with the joint between the asphalt mixture and the cement concrete panel in the composite specimen, and test the permeability coefficient at the joint. Step 7: Determine the minimum thickness: If there is no water seepage, the minimum thickness of the waterproof membrane used for water-stopping the edge of the bridge crash barrier is n. If there is water seepage, the thickness is increased in increments of 1 mm. A composite specimen with a waterproof membrane thickness of n+1 mm is selected to test the water seepage coefficient at the joint until there is no water seepage. The thickness at which the water seepage coefficient first reaches 0 is taken as the minimum thickness.
[0008] Preferably, the non-reinforced asphalt waterproof membrane described in step 3 is an asphalt film material without a reinforcing base. Because the waterproof membrane's function here is solely to fill the gaps at the junction of the asphalt pavement and the guardrail edge, it requires no reinforcing base to provide strength. The non-reinforced asphalt waterproof membrane is essentially an asphalt film, resulting in lower cost and a simpler production process.
[0009] Preferably, the specific steps for preparing waterproof membrane samples of different thicknesses in step 3 are as follows: Step 3.1: Place the non-woven bitumen waterproof membrane material in an oven and heat it until it reaches a fluid state; Step 3.2: Calculate the amount of pouring material m = V × ρ based on the thickness n of the waterproof membrane to be formed and the density ρ of the material used, where V is the volume of the waterproof membrane, determined by the size of the bonding surface; Step 3.3: Fold the silicone paper into the shape of the waterproof roll forming mold and place it in the mold. Place the mold on an electric furnace, which is placed on an electronic balance, and heat the mold to 160°C. Step 3.4: Pour the flowing waterproof membrane material into the mold according to the calculated amount, let it flow naturally and distribute evenly, then place it in a freezer at -5℃ to cool and solidify, then remove the sample from the mold along with the silicone paper and place it in a room temperature environment to warm up to room temperature.
[0010] Preferably, the formula for calculating the amount of asphalt mixture used in step 5 is: m= Where V is the volume of the asphalt mixture filling area. This represents the maximum theoretical density of the asphalt mixture. The void ratio of the asphalt mixture.
[0011] Preferably, the mold mentioned in step 3.3 is an open iron mold with dimensions of 300mm×50mm×30mm.
[0012] Preferably, before the water seepage test in step 6, Vaseline is applied to the surface of the asphalt concrete except for the joint between the asphalt mixture and the cement concrete panel, but Vaseline is not applied to the joint.
[0013] As a preferred option, when re-preparing the composite specimen with a thickness of n+1mm for the waterproof membrane in step 7, the original composite specimen is placed in a 160℃ oven to soften, and the waterproof membrane material on the sides of the asphalt mixture and cement concrete panel is removed, allowing the cement concrete panel to be reused and saving test time.
[0014] Preferably, in step 5, the waterproof membrane is placed between the cement concrete panel and the asphalt mixture.
[0015] The method for determining the minimum thickness of waterproof membrane for edge sealing of bridge crash barriers provided by this invention has the following advantages compared with the prior art: 1. This invention is the first to propose a systematic method for determining the minimum thickness of waterproof membrane for the specific water seepage channel at the edge joint of bridge crash barriers. It solves the problem of water entering the bridge deck pavement system from the junction of the bridge crash barrier and the asphalt pavement, fills the technical gap in material selection under this condition, and is of great significance for improving the durability of bridge deck asphalt pavement.
[0016] 2. This invention constructs a three-layer composite specimen consisting of "cement concrete panel + waterproof membrane + asphalt mixture" and uses a roller mill to compact it, which realistically simulates the stress and deformation environment of the waterproof membrane at the edge of the guardrail under actual compaction and service conditions. The test results are closer to the actual engineering situation.
[0017] 3. This invention proposes a dynamic determination scheme of "gradient thickness increase + water permeability coefficient detection" to ensure the minimum thickness of the waterproof membrane at the junction of the bridge deck pavement and the bridge crash barrier is watertight. At the same time, it avoids the construction difficulty and cost increase caused by excessive thickness. The test process is simple and the test results are accurate and reliable.
[0018] 4. The present invention has verified through examples the significant impact of different asphalt mixture types (such as SMA13 and SUP20) on the minimum thickness of waterproof membranes, proving that the method can achieve differentiated and precise design.
[0019] 5. This invention uses a non-reinforced bitumen waterproof membrane, which is directly bonded using its self-adhesive properties without the need for heat fusion, making construction safe and convenient. Compared with reinforced membranes, non-reinforced bitumen waterproof membranes have lower costs and simpler production processes, resulting in good economic benefits.
[0020] 6. This invention uses a gradient step size of 1 mm to balance experimental accuracy and efficiency, and proposes a solution for reusing cement concrete panels, thus saving experimental costs. Attached Figure Description
[0021] Figure 1 This is a diagram showing the location where the waterproof membrane is applied at the construction site.
[0022] Figure 2 This is a schematic diagram of the composite specimen prepared in the examples. Detailed Implementation
[0023] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific implementation methods.
[0024] Example 1: This example provides a method for determining the minimum thickness of waterproof membrane for edge sealing of bridge crash barriers. The specific implementation steps are as follows: S1, Molded cement concrete panel According to the cement concrete mix ratio used for the crash barrier (cement:fine aggregate:coarse aggregate:water;fly ash:water-reducing agent = 302:786:1041:170:77:4.536 (unit: kg / m³) 3 Molding 300 150 A 50mm thick cement concrete panel 1, as shown in Figure 2.
[0025] S2. Embed the cement concrete panel into the test mold. Place the cement concrete panel 1 tightly against one side of the mold and insert it into the mold. In this embodiment, the mold is the rut slab mold used in the T0703-2025 test in specification JTG3410-2025, with dimensions of 300mm×300mm×50mm. The cement concrete panel occupies half of the mold space (300mm×150mm×50mm), and the remaining space (300mm×150mm×50mm) is used to fill the asphalt mixture.
[0026] S3. Prepare waterproof membrane samples ① Place the SBS modified bitumen in a 170℃ oven and heat it to a fluid state. The waterproofing material used in this embodiment is a non-reinforced SBS modified bitumen waterproof membrane, that is, a pure bitumen film material without any reinforcing material.
[0027] ② Calculate the amount needed: Based on the thickness n (n=2mm, n=3mm, n=4mm, n=5mm) of the waterproof membrane to be formed and the density of the material used. ( =1.027g / cm 3 In this embodiment, the waterproof membrane is adhered to the side of the cement concrete panel, according to the formula m= = The calculated amounts of casting material for different waterproof membrane thicknesses are: m1=92g (n=2mm), m2=139g (n=3mm), m2=185.4g (n=4mm), and m4=231.8g (n=5mm). It is important to note that the formed area of the waterproof membrane should be consistent with the actual bonding surface area; otherwise, the prepared membrane cannot be correctly bonded to the side of the cement board.
[0028] ③ Fold the silicone paper into the shape of the waterproof roll forming mold and place it in the mold. Place the mold on an electric furnace, which is then placed on an electronic balance. Heat the mold to 160℃ using an infrared thermometer. In this embodiment, the mold used is an open-face iron mold with dimensions of 300mm × 50mm × 30mm, which matches the dimensions of the adhesive surface (300mm × 50mm).
[0029] ④ Pour the flowing SBS modified bitumen into the mold according to the calculated dosage, allowing it to flow naturally and distribute evenly. Then, place it in a -5℃ freezer to cool and solidify. Remove the sample from the mold along with the silicone paper and allow it to warm to room temperature to allow the waterproof membrane sample to bond with the cement concrete panel. This prepares waterproof membrane samples with thicknesses of 2mm, 3mm, 4mm, and 5mm for later use. The silicone paper acts as a release film here: during the preparation stage, it prevents the bitumen from sticking to the mold, ensuring complete demolding of the membrane; during the bonding stage, it protects the self-adhesive surface of the membrane, ensuring clean and effective adhesion.
[0030] S4. Paste waterproof membrane sample Adhere the side of a waterproof membrane sample with a thickness of n (initial value n=2mm) without silicone paper to the side of the cement concrete panel in step 1, then remove the silicone paper. Since the waterproof membrane of this invention is a non-reinforced bitumen material, it is self-adhesive and can be directly adhered to the cement concrete surface without the need for additional adhesive or hot-melt application. This self-adhesive cold application method avoids the impact of heat aging on material properties, making construction safe and convenient.
[0031] S5. Preparation of composite specimen plate ①According to the formula m= = Calculate the amount of SMA13 asphalt mixture needed. In this embodiment, the volume of the asphalt mixture filling area is V = 300mm × 150mm × 50mm = 2.25 × 10⁻⁶ mm. 6 mm 3 =2250cm 3 As can be seen from the mix design results of the asphalt mixture used for bridge deck paving (Table 2), =2.502, =4.0. Therefore, m = 5.4 kg.
[0032] ② According to the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG3410-2025), asphalt mixtures were prepared in the laboratory using a small mixing pot based on the design mix proportions (see Table 1). The asphalt mixture was then loaded into the remaining space (300mm×150mm×50mm) on the side of the cement concrete panel in the mold from step 2, according to the aforementioned asphalt mixture dosage. A composite specimen was formed using the roller rolling method (T0703-2025), and after cooling for 24 hours, it was removed. This composite specimen consists of a three-layer structure: cement concrete panel 1 (simulating a rigid guardrail) + waterproof membrane 3 (filling the joints) + asphalt mixture 2 (simulating flexible pavement), realistically simulating the stress and deformation environment of the waterproof membrane at the guardrail edge under actual rolling and service conditions. Figures 1-2 As shown.
[0033] Table 1. SMA13 Fee Ratio and Asphalt-Stone Ratio for Each Grade
[0034] Table 2 Optimal oilstone ratio, density, and porosity of SMA13
[0035] S6, Water seepage test ① Apply petroleum jelly to the asphalt concrete surface outside the joint between the asphalt mixture and the cement concrete panel to prevent water from seeping into the asphalt concrete surface during the water seepage test. Be careful not to apply it to the joint to ensure that the joint remains in its natural state.
[0036] ② The permeability coefficient at the joint of the composite specimen was tested according to the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG3410-2025). This test is to test the permeability at the joint, not the permeability of the asphalt mixture itself. Therefore, the center of the permeameter must be aligned with the joint between the asphalt mixture and the cement concrete panel in the composite specimen, rather than with the surface of the asphalt mixture.
[0037] S7. Determine the minimum thickness The waterproof membrane thickness is 2mm, and the water permeability coefficient is 10mL / min, which does not meet the requirement of being impermeable. The specimen was softened by heating in a 160℃ oven. The asphalt mixture and waterproof membrane sample of the composite specimen were removed. The cement concrete panel was reused, and a new composite specimen with a 3mm thick waterproof membrane was prepared according to steps S4-S6. The water permeability coefficient at the joints was tested, and it was found to be 0 (no water permeability). Therefore, in this embodiment, for this case of SMA13 asphalt mixture, the minimum thickness of the waterproof membrane used for edge sealing of the bridge crash barrier is 3mm.
[0038] Example 2: The method for determining the minimum thickness of waterproof membrane for edge sealing of bridge crash barriers provided in this example is as follows, wherein steps S1-S4 are basically the same as in Example 1: S1, Molded cement concrete panel According to the cement concrete mix ratio used for the crash barrier (cement:fine aggregate:coarse aggregate:water;fly ash:water-reducing agent = 302:786:1041:170:77:4.536 (unit: kg / m³) 3 Molding 300 150 50mm thick cement concrete panel.
[0039] S2. Embed the cement concrete panel into the test mold. Place the cement concrete panel tightly against one side of the mold and put the mold in.
[0040] S3. Prepare waterproof membrane samples ① Place the SBS modified bitumen in a 170℃ oven and heat it to a fluid state.
[0041] ② Calculate the amount needed: Based on the thickness n (n=2mm, n=3mm, n=4mm, n=5mm) of the waterproof membrane to be formed and the density of the material used. ( =1.027g / cm3 According to the formula m= = The calculated amounts of pouring material for different thicknesses of waterproof membrane were m1=92g (n=2mm), m2=139g (n=3mm), m2=185.4g (n=4mm), and m4=231.8g (n=5mm).
[0042] ③ Fold the silicone paper into the shape of the waterproof roll forming mold and place it in the mold. Place the mold on an electric furnace, which is then placed on an electronic balance. Heat the mold and measure the temperature with an infrared thermometer until it reaches 160℃.
[0043] ④ Pour the SBS modified bitumen in its flowing state into the mold according to the calculated amount, allowing it to flow naturally and distribute evenly. Then place it in a freezer at -5℃ to cool and solidify. Then remove the sample from the mold along with the silicone paper and place it in a room temperature environment to warm up to room temperature so that the waterproof membrane sample can bond with the cement concrete panel, thereby preparing waterproof membrane samples with thicknesses of 2mm, 3mm, 4mm, and 5mm for later use.
[0044] S4. Paste waterproof membrane sample Adhere the side of the waterproof membrane sample with thickness n (n=2mm should be used as the initial value) without silicone paper to the side of the cement concrete panel in step 1, and then peel off the silicone paper.
[0045] S5. Preparation of composite specimen plate ①According to the formula m= = Calculate the amount of SUP20 asphalt mixture needed. In this embodiment, the volume of the asphalt mixture filling area is V = 300mm × 150mm × 50mm = 2.25 × 10⁻⁶ mm. 6 mm 3 =2250cm 3 The mix design results of the asphalt mixture used for bridge deck paving (Table 4) show that... =2.553, =4.0. Therefore, m = 5.5 kg.
[0046] ② In accordance with the "Test Procedures for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG3410-2025), and based on the design mix proportion (see Table 3), asphalt mixtures were prepared in the laboratory using a small mixing pot. The asphalt mixture amount calculated in step S5① was loaded into the remaining space (300mm×150mm×50mm) on the side of the cement concrete panel in the mold in step 2. The composite specimen was formed using the roller rolling method (T0703-2025). After cooling for 24 hours, the composite specimen was removed.
[0047] Table 3. SUP20 Fee Ratio and Asphalt-Stone Ratio for Different Grades
[0048] Table 4. Volumetric Properties of SUP20 Mixture
[0049] S6, Water seepage test ① Apply petroleum jelly to the surface of the asphalt concrete panel, except for the joint between the asphalt mixture and the cement concrete panel, to prevent water from seeping into the asphalt concrete surface during the water seepage test. Be careful not to apply it to the joint.
[0050] ② Test the permeability coefficient at the joint of the composite specimen according to the "Test Procedure for Asphalt and Asphalt Mixtures in Highway Engineering" (JTG3410-2025). Note that the center of the permeability meter should be aligned with the joint of the composite rutted plate.
[0051] S7. Determine the minimum thickness The waterproof membrane thickness was 2mm, and the water permeability coefficient was 76mL / min, which did not meet the requirements. The specimens were placed in a 160℃ oven to soften them. The cement concrete panel was reused, and the asphalt mixture and waterproof membrane sample of the composite specimens were removed. Steps S4-S6 were repeated to prepare composite specimens with waterproof membrane thicknesses of 3mm, 4mm, and 5mm, and the water permeability coefficient at the joints was tested. The water permeability coefficient results are shown in Table 5. When the waterproof membrane sample thickness was 5mm, the water permeability coefficient was 0.
[0052] Table 5. Water infiltration coefficient under different waterproof membrane thicknesses
[0053] Therefore, in this embodiment, for SUP20 asphalt mixture, the minimum thickness of the waterproof membrane used for water-stopping the edges of bridge crash barriers is 5mm.
[0054] A comparison of Examples 1 and 2 shows that different asphalt mixture types have significantly different requirements for the minimum thickness of the waterproof membrane: SMA13 asphalt mixture requires a waterproof membrane thickness of 3 mm, while SUP20 asphalt mixture requires a waterproof membrane thickness of 5 mm. This proves that the method of the present invention can achieve differentiated and precise minimum thickness design for different asphalt mixtures.
[0055] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.
Claims
1. A method for determining the minimum thickness of a waterproof membrane for edge sealing of bridge crash barriers, characterized in that, Includes the following steps: Step 1: Molding cement concrete panels: Molding cement concrete panels according to the cement concrete mix proportions used for the crash barrier; Step 2, Embedding the test mold: Embed the cement concrete panel into the test mold; Step 3: Prepare waterproof membrane samples: Prepare waterproof membrane samples of different thicknesses using non-woven bitumen waterproof membrane material for later use. Step 4: Adhere the waterproof membrane sample: Utilize the self-adhesiveness of the non-woven bitumen waterproof membrane to directly adhere the waterproof membrane sample with a thickness of n to the side of the cement concrete panel, where the initial value of n is 2mm. Step 5: Prepare composite specimen plates: Mix asphalt mixture according to the mix proportion of asphalt mixture used for bridge deck paving, put it into the remaining space on the side of the cement concrete panel in the test mold, and form composite specimens by wheel rolling method. Remove them after cooling. Step 6, Permeability Test: Align the center of the permeability meter with the joint between the asphalt mixture and the cement concrete panel in the composite specimen, and test the permeability coefficient at the joint. Step 7: Determine the minimum thickness: If there is no water seepage, the minimum thickness of the waterproof membrane used for water-stopping the edge of the bridge crash barrier is n. If there is water seepage, the thickness is increased in increments of 1 mm. A composite specimen with a waterproof membrane thickness of n+1 mm is selected to test the water seepage coefficient at the joint until there is no water seepage. The thickness at which the water seepage coefficient first reaches 0 is taken as the minimum thickness.
2. The method for determining the minimum thickness of waterproofing membrane for the side water stop of bridge crash barrier according to claim 1, characterized in that: The non-reinforced asphalt waterproof membrane mentioned in step 3 is an asphalt film material without a reinforcing base.
3. The method for determining the minimum thickness of a waterproofing membrane for use in bridge crash barrier edge waterproofing according to claim 1, characterized in that: The specific steps for preparing waterproof membrane samples of different thicknesses in step 3 are as follows: Step 3.1: Place the non-woven bitumen waterproof membrane material in an oven and heat it until it reaches a fluid state; Step 3.2: Calculate the amount of pouring material m = V × ρ based on the thickness n of the waterproof membrane to be formed and the density ρ of the material used, where V is the volume of the waterproof membrane, determined by the size of the bonding surface; Step 3.3: Fold the silicone paper into the shape of the waterproof roll forming mold and place it in the mold. Place the mold on an electric furnace, which is placed on an electronic balance, and heat the mold to 160°C. Step 3.4: Pour the flowing waterproof membrane material into the mold according to the calculated amount, let it flow naturally and distribute evenly, then place it in a freezer at -5℃ to cool and solidify, then remove the sample from the mold along with the silicone paper and place it in a room temperature environment to warm up to room temperature.
4. The method for determining the minimum thickness of a waterproofing membrane for use in bridge crash barrier edge waterproofing according to claim 1, characterized in that: The formula for calculating the amount of asphalt mixture used in step 5 is as follows: m= ; wherein V is the volume of the asphalt mixture fill area, is the maximum theoretical density of the asphalt mixture, is the void ratio of the asphalt mixture.
5. The method for determining the minimum thickness of a waterproofing membrane for use in bridge crash barrier edge termination according to claim 1, wherein: In step 7, when preparing a new composite specimen with a waterproof membrane thickness of n+1mm, the original composite specimen is placed in a 160℃ oven to soften, and the waterproof membrane material on the sides of the asphalt mixture and cement concrete panel is removed, and the cement concrete panel is reused.
6. The method for determining the minimum thickness of a waterproofing membrane for use in bridge crash barrier edge termination according to claim 1, characterized in that: Before the water seepage test in step 6, apply petroleum jelly to the surface of the asphalt concrete except for the joint between the asphalt mixture and the cement concrete panel, but do not apply petroleum jelly to the joint.
7. The method for determining the minimum thickness of a waterproofing membrane for use in bridge crash barrier edge termination according to claim 1, wherein: The waterproof membrane is installed between the cement concrete panel and the asphalt mixture.