Common problems in the construction of main structure formwork

Hubei Wangke Template Co., Ltd. Share the common problems of the main structure of the building:

Reinforcement engineering expression:

It is difficult to ensure the spacing and position of small-diameter steel bars on the floor; the position of the negative bending moment steel bars is displaced; the main reinforcement at the corners of beams and columns The thickness of the protective layer is too small; the stirrup leaks after the template is removed.

Floor slab reinforcement prevention measures:

At the design stage, under the premise of satisfying structural safety and cost-effectiveness, small-diameter grade 3 steel bars should be preferred. Because the strength of the third-grade steel bar is greater than that of the first-grade steel bar, it is not easy to step on during construction. During the construction phase, measures should be taken when pouring the concrete. A horse stool should be placed on the formwork, and wooden boards should be laid. The construction personnel should operate on the boards and do not step on the steel bars directly.

Negative bending moment reinforcement prevention measures

Construction stage: When the steel bars are tied, a horse bench support of sufficient strength should be added under the negative bending moment steel bars. After the concrete is poured, use special tools to lift the steel bars to an accurate position at any time when plastering the surface. Before the concrete is finally set, it is strictly forbidden to trample on it;

Beam and column main reinforcement protection measures

When making beam and column stirrups, they should be processed in strict accordance with the designed cross-sectional size. Especially in the bending part of the stirrups, the effective bending radius should be determined through field tests under the conditions allowed by the specification to prevent the bending from being too small, which will cause the main reinforcement to not be close to the stirrups when tying the main reinforcement, and the protective layer will be excessive. Large (reduce the cross-sectional size of the member). The thickness of the protective layer of the main reinforcement refers to the smaller thickness, but not the larger the better.

Common template problems and prevention

Expression: loose joints, resulting in leakage of concrete during vibrating, uneven concrete surface, appearing Defects such as honeycomb pitted surface.

Governance measures: After the template is assembled, since most of the projects now use wooden templates, the joints Pasting a piece of transparent tape is a better way to solve the problem of grout leakage, but often when the steel bars are tied, due to the drag of the steel bars, the pasted tape will be damaged, which will adversely affect the concrete.

But a good material to effectively solve this type of grout leakage problem is to use double-sided tape between the template seams , Pasted on the edge of the board, this will basically reduce the common problem of concrete pouring leakage.

Common defects in concrete

Performance: concrete is not compacted or leaked by vibration, holes, leaking ribs, and loose surfaces appear after the formwork is removed , Cracks, etc.

Governance measures: Strengthen management staff’s awareness of standing by. When concrete is poured, the supervisor and Party A must supervise the whole process on site , Especially some key parts, such as the foundations and transition floors of high-rise buildings. Once there is a problem in these parts, it will cause great harm to the safety of the structure or the function of use.