Detailed explanation of construction process for bottom waterproof backing board (1000 words)

1、 Material selection and characteristics

Bottom waterproof backing board is a key material for building waterproofing, and the appropriate type should be selected according to the engineering requirements:

1. PVC backing board: It has strong corrosion resistance and is suitable for chemical environments. The thickness is usually 1.2-2mm, and its tensile strength (≥ 12MPa) and elongation (≥ 200%) need to be tested.   

2. HDPE polymer board: made of high-density polyethylene material with good impact resistance, commonly used in basements, with a recommended thickness of ≥ 1.5mm, and must comply with GB/T 17643 standard.   

3. Composite backing board: such as asphalt based+polyester fiber, which combines flexibility and waterproofness, suitable for areas with large temperature differences.   

Acceptance points: Check the factory certificate of conformity, thickness tolerance (± 0.1mm), and ensure that there are no bubbles or cracks on the surface.

2、 Grassroots treatment standards

The quality of the grassroots directly affects the waterproof effect and needs to be strictly handled:

1. Flatness: Check with a 2m ruler, with a gap of ≤ 3mm. The moisture content of the concrete base layer should be<8% (detection method: 1m ² plastic film covering for 24 hours without water droplets).   

2. Cleanliness: Thoroughly remove oil stains and floating dust, and if necessary, use a sandblasting machine for treatment. The internal and external corners should be made into circular arcs with R ≥ 50mm.   

3. Defect repair: Fill the cracks with epoxy mortar and apply interface agent to the honeycomb and hemp surface.

3、 Refined construction process

1. Bullet line positioning

-According to the layout diagram, mark the reference line with a long edge overlap of ≥ 80mm and a short edge overlap of ≥ 100mm.

-Complex nodes (pipe roots, floor drains) require pre cut boards and 3D scanners to assist in layout.

2. Adhesive construction

-Full adhesion method: Polyurethane adhesive (such as SikaBond-52) is used, with a coating amount of 1.2-1.5kg/m ². After scraping, it is left to air dry until it does not stick to the touch of the fingers (about 5-10 minutes).   

-Mechanical fixation: Stainless steel pressure strips (spacing ≤ 300mm) can be used to fix the light steel keel base, and the nail cap should be sealed with sealant.

3. Seam treatment

-Hot air welding: The welding gun temperature is controlled at 350-400 ℃, the welding speed is 0.3-0.5m/min, and the weld bead width is ≥ 20mm.

-Seam detection: Use a vacuum hood (-0.5Bar) to test the airtightness, or use an electric spark detector (3kV voltage).

4、 Key Node Enhancement Plan

1. Pipeline penetration location:

-Install prefabricated casing, fill the gap with expansion waterstop (such as BW type), and seal the outer ring with polysulfide sealant.   

2. Deformation joint treatment:

-U-shaped galvanized steel sheet cover (thickness ≥ 1.2mm) is set, filled with polyethylene foam rod, and the cover width is ≥ 150mm on each side.

3. Transition zone of vertical wall:

-The height of the waterproof layer should be ≥ 300mm, and the opening should be closed with a metal pressure strip and sealed with silicone weather resistant adhesive.

5、 Quality acceptance standards

1. On site inspection:

-Peel strength test (refer to GB 23457): Cut a 100mm wide specimen and stretch it at a speed of 100mm/min, with a strength of ≥ 0.5N/mm.   

-48 hour water storage test, water depth ≥ 20mm.

2. Data archiving:

-Including material retest report, concealed engineering records, and infrared thermal imaging detection report (detection hollowing rate<5%).

6、 Common problem solutions

1. Hollow drum problem:

-Partial incision grouting (epoxy resin slurry), or using vacuum negative pressure repair technology.   

2. Weld cracking:

-After removing the defective section, use the same material patch for hot melt repair, and the patch size should exceed the defect edge by 50mm.

3. Long term durability:

-It is recommended to conduct infrared testing once every 5 years, and anti aging coatings (such as polyurethane topcoat) should be applied to areas exposed to ultraviolet radiation.

7、 Outlook on Innovative Processes

1. Self repairing backing plate: Built in microencapsulated asphalt, which can automatically repair cracks.   

2. Intelligent monitoring type: embedded with fiber optic sensors to monitor leakage in real time.   

3. Application of green materials: Environmentally friendly boards made of recycled HDPE (with a recovery rate of ≥ 85%) are used.

Through the standardized construction and technological innovation mentioned above, the bottom waterproof backing board system can achieve the designed service life (usually ≥ 25 years). In actual engineering, it is necessary to flexibly adjust according to the site conditions. It is recommended to hire a professional waterproof qualification team for construction to ensure the quality of the project.