Construction technology
pvc rolls are generally produced by cold bonding, empty laying, mechanical fixation, and sometimes by a unique hot air welding process. For complex waterproofing construction areas, dedicated accessories should be used. Assembly construction of pvc special accessories.
1. Cold bonding method
The construction method of adhering pvc rolls to the base layer by cold operation using a special adhesive for PVC rolls is called the cold bonding method.
According to different waterproof design requirements, cold bonding methods can be divided into full bonding or local bonding methods.
(1) The full bonding method is a construction approach in which all pvc rolls are bonded to the base layer.
1) During construction, the first step is to pre-lay the PVC roll material naturally and flat on the surface of the base layer marked with lines (without bonding at first), ensuring it is smooth and straight without distortion.
2) The longitudinal lap width of the roll material is 50mm, and it should be appropriately cut. The horizontal part is treated with butt joint, and a 200 to 250mm wide non-composite layer (Class N) is used on it. PVC sheet covering lap welding.
3) Fold the long sides of one or more rolls in half (about 10 meters). Apply special adhesive to the base layer and the surface of the rolls respectively from the folded area. When the adhesive dries until it is no longer sticky to the hand, close and stick the pre-laid roll surfaces together and press them firmly with a roller. Then fold up the other unfolded parts and continue to operate from the folded area as described before. Repeat this process in sequence to firmly and compacted them. Finally, the seam welding construction is carried out.
(2) Partially paste the roll material. When laying PVC rolls, the rolls and the base layer should be adhered to the base layer by dot bonding or strip bonding.
Spot bonding: The sheet material is bonded to the base layer in a point-like manner. No less than 5 points should be bonded per square meter, with each point having an area of 100mm×100mm.
Strip bonding: The roll material is bonded to the base layer in a strip form. Each roll material should have no less than two bonding surfaces with the base layer, and the width of each sheet should be no less than 150mm.
2 Empty spread method
When laying PVC waterproof membrane, the membrane and the base layer are only bonded within a certain width around the entire waterproof layer. The construction method of not bonding the remaining parts. The construction process flow of the empty paving method is as follows:
Base leveling and cleaning - marking lines - pre-laying rolls of materials - lap welding of rolls of materials - treatment of special parts - fixing and edge pressing - edge sealing with sealing materials - acceptance.
Firstly, the pre-laying of the roll material should follow the full bonding method, with a longitudinal lap width of 50mm. Secondly, only fully bond the rolls around the entire waterproofing project and weld the lap joints. Horizontally, the butt joint treatment is adopted, and on it, 200 to 250mm wide PVC rolls without composite layers (Class N) are covered and overlapped, and then welded.
3 Mechanical fixation method
That is, a construction method that uses mechanical fastening fasteners to connect the sheet material with the base layer.
(1) During construction, pre-laying should be carried out first, and the full bonding method can be referred to for operation. The longitudinal lap width is 100mm, of which 50mm is used as a fastener. The fastener needs to pass through the insulation layer and be fixed on the structural layer.
(2) According to the fixed intervals designed and calculated, drill holes with an impact drill first, with the hole diameter slightly smaller than the outer diameter of the fixed screws. After positioning the fixing parts, tighten them with an electric screwdriver. Repeat the operation in sequence afterwards. For each lap joint, welding is carried out. In the transverse direction, butt treatment is adopted, and the lap joint is covered with 200 to 2500mm wide non-composite layer (Class N) roll material for welding.
The welding process of PVC sheet materials
The longitudinal lap width between PVC rolls is 50mm and the transverse width is 100mm. When using the welding process, the welding nozzle should form a 45-degree Angle with the welding direction. The Angle, the pressure roller should be parallel to the welding nozzle and keep a distance of about 5mm. The rolling speed should not be too fast.
Welding is carried out using a small welding nozzle with a width of 20mm, usually in two passes. The welding temperature is controlled at the 6th gear, and the effective width of each pass is 15mm to 20mm.
It is advisable to use a large welding nozzle with a width of 40mm for welding in one pass. The welding temperature should be controlled at the 7th gear, and the effective welding width should be 25mm.
Welding requirements: A pre-weld should be carried out before welding. The width should not be too wide to prevent hot air from escaping during welding and affecting the welding quality. There should be molten slurry overflow at the welding edge, but no charring should occur.
Regarding the effective welding width, it refers to the distance from the stripping point of the coil to the edge of the molten slurry. Ensuring the effective welding width is one of the main indicators for inspecting the welding quality.
