Wooden formwork construction to avoid common quality problems in engineering

　　Before installing the template, check the quality of the template first. Those that do not meet the quality standards shall not be put into use

　　⑵ Basic template

　　1) The strip foundation should prevent the phenomenon of the upper opening of the formwork not being straight and the width not being accurate along the entire length direction of the foundation, the lower opening being trapped in the concrete, the upper section of the concrete being damaged during formwork removal, and the bottom upper formwork not being firm.

　　Preventive measures:

　　a. The template should have sufficient strength and stiffness, and the verticality during formwork support should be accurate.

　　b. The upper opening of the template should be nailed with wooden straps to control the width of the upper opening of the strip shaped foundation, and a long line should be drawn to ensure a straight upper opening

　　c. At certain intervals, support the lower mouth of the upper section template on the steel hoop bracket; Temporary wooden supports can also be used to maintain consistent height of the side formwork.

　　d、 When supporting directly at the edge of the soil pit, wooden boards should be placed underneath to expand its load-bearing surface. A splicing strip should be added at the longitudinal joint of the two templates to make the board surface flat and firmly connected

　　2) The cup shaped foundation should prevent inaccurate centerline and displacement of the cup mouth template; The phenomenon where the core formwork floats during concrete pouring and cannot be lifted during formwork removal

　　preventive measure

　　a、 When supporting the cup shaped foundation formwork, the centerline position and elevation should be accurate. When supporting the upper section formwork, a lift bar should be used to ensure accurate position. The role of the support wood is to separate the lift bar slightly from the lower section concrete surface, making it easier to level the concrete surface.

　　b、 The cup core template should be planed and straight assembled, and the outer surface of the core mold should be coated with isolation agent. Several small holes should be drilled at the bottom to facilitate ventilation and reduce buoyancy.

　　c、 When pouring concrete, the material should be evenly cut and vibrated around the core mold.

　　d、 Scaffolding boards shall not be placed on templates.

　　e、 The dismantled cup core template should be controlled based on the temperature and concrete solidification during construction. Generally, it can be lightly tapped with a hammer or pulled with a pry bar before and after initial setting.

　　⑶ Beam formwork: prevent unevenness of the beam body, unevenness and deflection of the beam bottom, explosion of the beam side formwork, and embedding of local formwork between columns and beams; The phenomenon of difficulty in dismantling

　　Preventive measures:

　　a、 When supporting the beam formwork, the principle of wrapping the edge formwork with the bottom formwork should be followed. At the connection between the beam formwork and the column formwork, the influence of the longitudinal expansion of the beam formwork after moisture absorption should be considered. The cutting size should generally be slightly shortened to prevent the concrete from being embedded in the column after pouring

　　b、 The beam side formwork must be provided with a presser foot plate, slant support, and the beam side shall be nailed after the guy wire is straight. The beam bottom formwork shall be arched as required.

　　c、 Before pouring concrete, the formwork should be fully wetted with water.

　　(4) Column formwork: Prevent column formwork from exploding, protruding cross-sectional dimensions, leakage of grout, loose mixed soil, honeycomb and pitted surfaces, skewness, and twisting of the column body.

　　preventive measure

　　a、 Nail firmly according to the required spacing between column hoops

　　b、 When supporting the column formwork in rows, the column formwork at both ends should be erected first. After straightening and verifying the correct position, the long line should be pulled through at the top before the middle column formwork is erected

　　c、 The slant support around shall be firm.

　　d、 For higher columns, temporary pouring holes should be left on one side of the middle of the template for pouring concrete. A vibrating rod should be inserted, and when the concrete is poured to the temporary opening, it should be tightly closed

　　(5) Plate template: To prevent the phenomenon of downward bending in the middle of the plate and uneven concrete surface at the bottom of the plate.

　　Preventive measures:

　　a、 The thickness of the floor formwork should be consistent, and the timber for the grid should have sufficient strength and stiffness. The grid surface should be flat

　　b、 The supporting materials should have sufficient strength, be firmly connected to each other in front, back, left, and right, and the supporting system should be stable.

　　Main safety technical measures

　　During the process of formwork support, safety operating procedures should be followed. If there is a pause during the process, the installed support top and formwork should be firmly connected, and no empty support should be allowed to float. During the interval of demoulding, loose components and templates should be transported away to prevent falling and injuring people.

　　When dismantling the formwork, a scaffold board should be erected.

　　When dismantling the formwork outside the floor, measures should be taken to prevent high-altitude falls and prevent the formwork from falling outward.

　　Finished product protection

　　⑴ Adhere to cleaning the surface of the template and applying release agent after each use.

　　⑵ Install layer by layer according to the location of the floor slab to reduce losses.

　　Materials should be classified and stacked neatly according to the designated positions in the layout plan.