Classification and Characteristics of Formwork in Construction Engineering
At present, the main types of building formwork used in China's construction industry are wood building formwork, steel and wood building formwork, building wood plywood, steel and bamboo building formwork, plastic building formwork and so on. Next, we will compare the characteristics of various types of building formwork:
Bamboo plywood formwork has high strength, good toughness, and its static bending strength is 8-10 times of wood strength and 4-5 times of wood plywood strength. The use of bamboo plywood formwork can reduce the number of supports.
The bamboo plywood formwork has wide width and few joints. The basic size of the sheet is 2.44 meters X1.22 meters, which is equivalent to the area of 6.6 small steel formwork P3015. The supporting and disassembling speed is fast.
The surface of bamboo plywood formwork is smooth and smooth. The adsorptive force of bamboo plywood formwork is only one eighth of that of steel formwork. Therefore, it is easy to demould and the surface of concrete is smooth and smooth. It can cancel plastering operation and shorten the time limit of decoration operation.
Bamboo plywood formwork has good water resistance and does not glue when boiled for 6 hours. After boiling and freezing, it can still maintain high strength. The surface water absorption of bamboo plywood formwork is close to that of steel formwork, and pouring concrete with bamboo plywood formwork can significantly improve the water retention of concrete surface. In the course of concrete maintenance, water does not deform, which is convenient for maintenance.
Bamboo plywood formwork is anti-corrosion and moth-proof.
The thermal conductivity of bamboo plywood formwork is 0.14-0.16w/m.k, which is much smaller than that of steel formwork, and is conducive to construction heat preservation in winter.
Bamboo plywood formwork has high turnover times and obvious economic benefits. It can be used on both sides without frame.
The characteristics of wooden building formwork: The species used for wooden building formwork can be selected according to the actual situation of different regions, and pine and Chinese fir are commonly used. Wood building formwork consumes a large amount of wood and has low reuse efficiency, but it is easy to use.
Steel-wood building formwork: The Steel-wood building formwork is a stereotyped building formwork with angle steel as the frame and wooden building formwork as the panel. Its advantage is that it can make full use of short wood and can be used repeatedly.
Building wood plywood: Building wood plywood is a stereotyped building template with plywood as the panel and angle steel as the frame. The plywood panel overcomes the disadvantage of unequal orientation of wood and has good mechanical properties. This kind of building formwork has the advantages of high strength, low self-weight, non-warping, non-cracking, large plate width and few joints.
Steelbamboo building formwork: Steelbamboo building formwork is a stereotyped building formwork with angle steel as the frame and bamboo plywood as the panel. This kind of building formwork has the advantages of large steel, not easy to deform, light weight and easy operation.
Steel building formwork: Steel building formwork is generally made into stereotyped building formwork, with connecting components assembled into various shapes and sizes, suitable for a variety of structural forms, and widely used in the construction of cast-in-place reinforced concrete structure. Steel building formwork has the largest investment in one time, but its turnover rate is high. In the process of using, attention should be paid to the maintenance and prevention of rust in order to prolong the service life of steel building formwork.
Others, such as plastic building formwork, FRP building formwork and aluminium alloy building formwork, have the characteristics of light weight, high toughness, easy assembly and high turnover rate, but because of the high cost, they have not been widely used in construction.
Each construction enterprise can choose suitable building formwork according to its own needs.
D < pF < LNormal > 9. The construction of stairwell moulding should take full account of the needs of decoration work.
10. Major Technical Quality Problems in Construction of Formwork Supporting Structures
1) Location control: There are positioning problems in this project, whether wall pillars or structural beams. Many component positioning can not be simply understood from the drawings. Therefore, it is necessary to ensure the correctness of positioning before template installation, and can not make template or affect positioning layout because of no positioning.
2) Cleaning of construction joints: Before the formwork is closed or installed, all concrete construction joints must be cleaned up so as to ensure the tightness of grouting during the superstructure concreting.
3) Treatment of beam-to-column joints: The joint of beam-to-plate wall and column can be solved by controlling the construction quality and size of the column formwork; when the column and the beam-to-plate are separately poured, before the installation of the beam formwork, the manufacture and installation of the formwork of the joint of the column head should be carried out first.
4) Reinforcement positioning: Whether wall column or beam, there is a problem of reinforcement positioning. Before the template is closed, the reinforcement positioning bar must be fired and welded according to the positioning control line.
5) Elevation control: This project involves a lot of elevation control, must be very careful.
6) Reservation of reinforcement: There are many reinforcements in this project, including structural column, structural column and exterior wall decoration line, which can not be omitted. At the same time, the accuracy of location should be ensured. Especially for the insertion of structural column, the position and size of the insertion bar must not be allowed to make mistakes.
7) Processing of reserved holes: The reserved holes should not only be well sealed and firmly installed, but also be checked for elevation and reinforcement before the template is closed.
8) Installation of construction buried parts.
9) The quality control of stairs, the treatment of construction joints, the treatment of diagonal running and the joints between walls and columns should be well controlled.
