Before the construction of pile caps and piers, the special scheme for pier construction shall be examined and approved, and the construction disclosure meeting shall be organized in time to ensure the construction quality and safety. Before template processing, do a good job in reviewing the manufacturer's qualification and processing capacity, strictly control the processing quality, and the template accuracy should meet the specification requirements.
Some engineering columns are more than 20 meters, so the construction unit should assign special personnel to check the verticality of pier, formwork installation, concrete pouring and other important processes. In view of the high column well, the verticality should be monitored by designated personnel at the site, and the supervisors should also focus on supervision and inspection.
Coordinate positioning control of bearing platform: according to the construction technology of the construction unit, the positioning of foundation pit edge, cushion edge, formwork edge and steel bar is based on the coordinate of column center line, and the details are set out with steel ruler and total station. We mainly check by synchronous repetition and centering steel rule distance method to ensure accurate positioning; In terms of data, the construction unit is required to provide the coordinate setting-out record of the center point of the column and the setting-out record of the edge line of the formwork based on it.
Verticality control of bearing platform: the verticality of bearing platform template is mainly checked by visual inspection and steel rule distance method according to the measuring edge; By suggesting that the construction unit increase the horizontal fulcrum and strengthen the vertical fulcrum, the overall verticality and stability of the foundation steel skeleton are controlled, and good control results are obtained.
Column coordinate positioning control: coordinate positioning control: the center positioning of embedded steel bars in the column requires accurate positioning of well-shaped supports according to the center coordinates of the column before the steel bars are erected, and timely inspection by steel rule distance method; After the steel bars are bound, the center deviation error is rechecked by pulling the distance of the middle steel ruler, and whether the thickness of the concrete protective layer meets the requirements is predicted. Column template positioning is based on column coordinates, and the inner edge of column template is set. Check whether the template margins are equidistant, whether the protective layer thickness is uniform, whether the center line spacing between two adjacent columns meets the design value, and whether the diagonal line is offset by the steel rule distance method. In terms of data, the construction unit is required to provide the setting-out records of the center point of the column and the edge of the template.
Verticality control of column: check the verticality of longitudinal main reinforcement of concealed column with plumb and steel rule distance method, and require the construction unit to control the installation accuracy with central plumb during construction; Before pouring, use theodolite to check the verticality of formwork, and when pouring, use plumb and steel rule distance method to check the deviation. If the first layer has not been poured, it should be rechecked once, and it should be found and adjusted in time.
When pouring concrete, clean the column first, and pour the transition layer with fine stone concrete or high-grade semi-stone concrete, and control the transition layer at about 5cm. The first blanking amount of the column should be calculated according to the effective radius of the vibrator and the column section. It is forbidden to vibrate when the material is full. The concrete vibrating of small section columns or columns with high reinforcement ratio can be mainly vibrating rods, supplemented by steel rods. Steel bars are only used for guiding materials and should not be used as vibrating tools. Construction joints of columns shall be set according to the design and specification requirements.
For continuous casting pier construction, the supervisor is present throughout the whole process, and it is required that each vehicle must detect the concrete slump, and the slump should be controlled between 8- 10cm. Concrete construction should be carried out in strict accordance with the construction methods of layered pouring and layered vibrating, so as to ensure that no vibration is missed or excessive, and that the inside is solid and the outside is light. Concrete should be covered with thermal insulation materials for curing. For columns, sand with a thickness of about 5cm should be paved at the top of the column to ensure the curing quality of concrete at the top of the column.
The formwork shall be dismantled with care. After dismantling, the construction personnel shall clean, repair and maintain the formwork in time to ensure that the formwork is in good condition. Strictly control the dismantling time of column formwork; Formwork that cannot be trimmed due to severe deformation can no longer be used.
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