In order to give full play to the various advantages of plastic formwork, it is necessary not only to pay attention to the selection of formwork materials and fastening materials, but also to strengthen the control during on-site construction.
1. Material selection
(1) Formwork materials: 17mm plastic formwork should be selected, special beam bottom formwork for plastic formwork, special yin and yang corners for column wall, special adjustment form for column wall, standard plastic 50mm×100mm for the back strap of the formwork, and special supporting fixture for plastic shuttering panels.
(2) Fastening material: Φ12 pairs of tension screws are used as the fastening materials, among which, the waterproof concrete adopts the pair of tension screws with water stop rings; the shear walls and frame beams on the ground use the pair of tension screws to wear PVC casings.
2. Process control
During the construction operation of plastic formwork, it must be carried out in strict accordance with the process of formwork engineering disclosure. On-site technicians should require workers to construct in strict accordance with the drawings to ensure that the location and size are accurate. Taking the wall formwork as an example, the following points should be done in terms of on-site quality control.
(1) Pay attention to the order in which the plastic formwork is installed: check before the formwork is supported; when starting the formwork, first set the side formwork, and then bind the steel bars. After installing the tie bolts, support the other side mould; then correct whether the installation position of the template is consistent with the drawing, if it is consistent, tighten the tie bolts to ensure that the support is fixed, and conduct a comprehensive inspection after completion.
(2) Before setting up the wall formwork, the debris in the wall must be cleaned up to ensure that the wall is free of contamination. Then pop out the edge of the wall and the in-position line of the plastic formwork. At the same time, the axis of the large corner of the outer wall should be marked, and a mortar leveling layer should be prepared or a sponge strip should be pasted at the bottom of the formwork to prevent leakage of the mortar.
(3) Before installing the wall plastic formwork, the limited steel bars should be installed according to the wall thickness.
(4) The installation of the formwork starts from the inner corner of the shear wall to ensure the accuracy of the external dimensions and verticality of the building; after the formwork on one side is set up, the pull bolts can be worn, and then the formwork on the other side can be set in place for adjustment, align with the holes of the through-wall bolts for fixing.
(5) Before the formwork is installed, it is necessary to check whether the schematic drawing of the formwork and its size and position are consistent with the drawing. When supporting the formwork, the verticality of the formwork installation should be corrected to ensure that the joints are tight, and a special external angle should be used at the corner (external angle) of the wall. Internal corner mold, and put on the tie bolts to fix it with the corresponding internal corner mold or wall formwork to ensure that the angle is square and does not run off the mold.
(6) The shear wall formwork adopts the combined stereotyped mode. The size of the plastic template should be determined according to the storey height. Usually, a free combination stereotyped template with a width of 500~1500mm is used. The tension screw and the steel pipe will be connected, the standard pile spacing is 250mm, the steel pipe spacing is 600mm, and the tension screw spacing is 500mm×500mm.
In order to ensure the quality of the project and not leave hidden safety hazards, technical control should be strengthened during construction. In the process of hoisting and transporting the plastic formwork, a special person is designated to direct, hook and bundle the formwork to ensure safety and firmness.
When the wall formwork is assembled on site, the design requirements and construction technical requirements should be strictly configured. Carry out the installation of the previous layer of composite plastic formwork.
When the lower plastic formwork cannot independently reinforce the supports, reinforcement and stabilization measures must be formulated according to the actual situation. After the reinforcement is completed and the inspection meets the requirements, the upper plastic formwork can be installed.