What are assembly requirements on external formwork?
Below text tells assembly requirements on external formwork which will be used to produce concrete girder with post-tensioning method.
1. Before assembling external formwork, check whether formwork surface is smooth, distorted, with cement remained, whether it is clean at joints and in depression of end formwork; whether there is defects and deformation caused by collision in connecting end face and bottom face of formwork, whether support frame of vibrator and welding joints of its formwork have cracks and damages, repair it to be qualified if above problems are found. Coat mould release agent carefully and uniformly on the formwork surface (coat it with a proportion 1:10 in sunny days, 1:1 in rainy days), no omission is permitted. Before assembling side formwork, also check whether bottom formwork goes down and whether reversed deflection meets the design demand, especially note relative height difference at 4 support base positions of concrete girder shall be not more than 2mm.
2. Assemble side formwork: side formwork is connected with one end at inside of girder casting base, one end outside is connected with adjustable jack or screw. Install side formwork after bottom formwork inspection is qualified, make hinged shaft on formwork base rotate by adjusting jack (or adjustable screw), as height of mould highly conforms to design height of concrete girder, and inclination angle of the formwork coincides with design inclination angle of concrete girder sides, and after formwork at two sides is connected closely with bottom formwork, then connect side formwork and bottom formwork with bolts to be an entity. Some support poles need to be added at outside of mould to meet demands and ensure the entire stiffness of mould. Squeeze tightly the installed side formwork, no more adjustment is done if there is no serious deformation.