Seam treatment process
Joint treatment of FRP panels is a key step in ensuring waterproofing and structural integrity, and mainly includes processes such as sealant filling, fiberglass cloth reinforcement, and surface finishing.
Seam treatment process
- Substrate Preparation
The joint surface must be thoroughly cleaned to remove oil, dust, and moisture. Clean the surface with solvents such as acetone or xylene, then wipe it dry with a clean cloth, ensuring the substrate is completely dry. For uneven joints, use an angle grinder to smooth them, removing burrs and protrusions.
- Sealant Filling
Use single-component or two-component sealant to fill the joints. Single-component sealant can be used directly; two-component sealant must be mixed evenly at a ratio of A:B = 10:1 or 5:1. Use a manual caulking gun to evenly apply the sealant into the joint, controlling the gun movement speed at 300-400 mm/min, keeping the nozzle at a 45° angle to the work surface, ensuring the sealant is applied fully and without air bubbles. For joints wider than 15 mm, multiple applications are required.
- Fiberglass Reinforcement
Lay fiberglass cloth at the joint for reinforcement. The "cross-hatching method" is used for caulking, with each layer 90° out of alignment, an overlap width of ≥50mm, and a seam stagger of ≥100mm. The resin usage for each layer is controlled at 0.3kg/m², and it is smoothed with a scraper to ensure uniform thickness (±0.1mm). An intermediate inspection is performed after three layers; a detachment area of ≤5% is considered acceptable.
- Surface Finishing
Use a semi-circular stainless steel scraper (10mm radius) to apply the sealant at a 30° angle, applying even pressure to create a concave surface (depth 1/3 of the seam width). The finished surface should be smooth and free of bubbles, insufficient sealant, and drips. Remove the masking tape after the sealant is semi-dry to complete the surface treatment.
Quality Control Key Points
- Visual Inspection
The adhesive joint surface should be smooth and continuous, free from missing adhesive, drips, scratches, and natural transitions at the joints. Use a 5x magnifying glass to inspect for impurities larger than 0.5mm in diameter.
- Dimensional Control
The allowable deviation for adhesive joint width is ±0.5mm, and the allowable deviation for depth is ±0.3mm. Measure every 20m using dedicated calipers, record the data, and create a quality control chart.
- Curing Test
Curing time at room temperature ≥48 hours. The curing time doubles for every 5°C decrease in ambient temperature. Use a Barcol hardness tester; the hardness value should reach at least 90% of the substrate's standard value.
- Water Retention Test
After the waterproof layer is fully cured (generally more than 24 hours), conduct a water retention test at a height of approximately 1.5 meters. Observe the water level drop after 24 hours. No water drop indicates that the waterproofing is qualified.
Special Treatment for Special Areas
- Corner Joints
A "cross-positioning method" is used for adhesive application. First, a 10mm diameter circular adhesive pad is applied to the inside of the corner. Then, adhesive is applied from both directions, converging at the center, ensuring a radius of curvature ≥ 20mm.
- Expansion Joints
Expansion joints ≥ 20mm wide utilize a composite structure of "backing material + sealant + stainless steel cover plate." The backing material is closed-cell polyethylene foam. After applying the sealant, a 1.2mm thick metal strip is embedded.
- Drainage Holes
Φ5mm drainage holes are installed every 500mm at the bottom of the joint. The hole openings are covered with a waterproof and breathable membrane to ensure unobstructed drainage while preventing air infiltration.
Precautions
The ambient temperature for construction should be between 10-40℃, and the relative humidity should not exceed 80%. Construction is prohibited in rainy, snowy, windy, or condensation-prone weather conditions. Construction personnel must wear protective gloves, goggles, and other safety equipment, and clear warning signs must be posted at the construction site.